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Yamazaki Y, Tohara H, Hara K, Nakane A, Wakasugi Y, Yamaguchi K, Minakuchi S. Excessive anterior cervical muscle tone affects hyoid bone kinetics during swallowing in adults. Clin Interv Aging 2017; 12:1903-1910. [PMID: 29184396 PMCID: PMC5685148 DOI: 10.2147/cia.s143175] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Purpose This study aimed to determine whether excessive neck muscle tone affects hyoid bone kinetics during swallowing using videofluorography (VF) in an unnatural posture in healthy individuals. Subjects and methods Subjects were 28 healthy adults (12 men, 16 women; mean age, 39.75±9.50 years) without any history or present complaints of swallowing disorders. We first established the participant’s posture a reclining wheelchair that was adjusted to a 30-degree angle with the headrest (without excessive neck muscle tone) or without headrest (with excessive neck muscle tone), used an electromyogram above the mylohyoid muscle to represent the suprahyoid muscles and above the sternohyoid muscle to represent the infrahyoid muscles to confirm neck muscle tone, and then conducted VF of swallowing measurements. Videofluorographic images were obtained when 5 mL of 50% (w/v) barium sulfate was being swallowed, and hyoid bone coordinate (the resting position and the elevated position), extent of horizontal and vertical hyoid bone elevation, as well as duration and velocity of hyoid bone elevation were evaluated (x-axis and y-axis coordinates for the resting position of hyoid bone are referred to as Xr and Yr, respectively; those for the elevated hyoid bone position induced during swallowing are referred to as Xs and Ys, respectively). Results In the resting position of the hyoid bone, the Yr coordinates in those with excessive neck muscle tone were significantly lower than in those without excessive neck muscle tone. Vertical hyoid bone elevation and hyoid bone elevation velocity were significantly higher with excessive neck muscle tone than without excessive neck muscle tone, whereas horizontal elevation showed no significant differences. Conclusion Our findings suggest that the generation of neck muscle tone due to inappropriate posture may encourage hyoid depression and increase the extent of hyoid bone elevation, thereby increasing the risk of aspiration.
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Affiliation(s)
- Yasuhiro Yamazaki
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Haruka Tohara
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Koji Hara
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ayako Nakane
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoko Wakasugi
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kohei Yamaguchi
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
| | - Shunsuke Minakuchi
- Department of Gerodontology, Tokyo Medical and Dental University, Tokyo, Japan
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Rozand V, Senefeld JW, Hassanlouei H, Hunter SK. Voluntary activation and variability during maximal dynamic contractions with aging. Eur J Appl Physiol 2017; 117:2493-2507. [PMID: 29058113 DOI: 10.1007/s00421-017-3737-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2017] [Accepted: 10/02/2017] [Indexed: 12/31/2022]
Abstract
Whether reduced supraspinal activation contributes to age-related reductions in maximal torque during dynamic contractions is not known. The purpose was to determine whether there are age differences in voluntary activation and its variability when assessed with stimulation at the motor cortex and the muscle during maximal isometric, concentric, and eccentric contractions. Thirty young (23.6 ± 4.1 years) and 31 old (69.0 ± 5.2 years) adults performed maximal isometric, shortening (concentric) and lengthening (eccentric) contractions with the elbow flexor muscles. Maximal isometric contractions were performed at 90° elbow flexion and dynamic contractions at a velocity of 60°/s. Voluntary activation was assessed by superimposing an evoked contraction with transcranial magnetic stimulation (TMS) or with electrical stimulation over the muscle during maximal voluntary contractions (MVCs). Old adults had lower MVC torque during isometric (- 17.9%), concentric (- 19.7%), and eccentric (- 9.9%) contractions than young adults, with less of an age difference for eccentric contractions. Voluntary activation was similar between the three contraction types when assessed with TMS and electrical stimulation, with no age group differences. Old adults, however, were more variable in voluntary activation than young (standard deviation 0.99 ± 0.47% vs. 0.73 ± 0.43%, respectively) to both the motor cortex and muscle, and had greater coactivation of the antagonist muscles during dynamic contractions. Thus, the average voluntary activation to the motor cortex and muscle did not differ with aging; however, supraspinal activation was more variable during maximal dynamic and isometric contractions in the old adults. Lower predictability of voluntary activation may indicate subclinical changes in the central nervous system with advanced aging.
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Affiliation(s)
- Vianney Rozand
- Exercise Science Program, Department of Physical Therapy, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201, USA
| | - Jonathon W Senefeld
- Exercise Science Program, Department of Physical Therapy, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201, USA
| | - Hamidollah Hassanlouei
- Exercise Science Program, Department of Physical Therapy, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201, USA
| | - Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, P.O. Box 1881, Milwaukee, WI, 53201, USA.
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53
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Bellumori M, Uygur M, Knight CA. High-Speed Cycling Intervention Improves Rate-Dependent Mobility in Older Adults. Med Sci Sports Exerc 2017; 49:106-114. [PMID: 27501360 DOI: 10.1249/mss.0000000000001069] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE The aim was to determine the feasibility of a 6-wk speed-based exercise program that could be used to initiate new exercise behaviors and to improve rapid movement in older adults approaching frailty. METHODS The intervention group included 14 older adults (3 males and 11 females; mean ± SD, age = 70 ± 7.6 yr, height = 1.6 ± 0.11 m, mass = 76.8 ± 12.0 kg, body mass index = 27.7 ± 4.7 kg·m). The control group included 12 older adults (6 males and 6 females; mean ± SD, age = 69.2 ± 6.9 yr, height = 1.7 ± 0.09 m, mass = 78.2 ± 10.9 kg, body mass index = 25.3 ± 2.7 kg·m). Subjects included active older adults, including regular exercisers, but none were engaged in sports or exercises with an emphasis on speed (e.g., cycling spin classes or tennis). Stationary recumbent cycling was selected to minimize fall risk, and low pedaling resistance reduced musculoskeletal and cardiovascular load. Two weekly 30-min exercise sessions consisted of interval training in which subjects pedaled at preferred cadence and performed ten 20-s fast cadence intervals separated by 40 s of active recovery at preferred cadence. RESULTS Significant group-time interactions (P < 0.05) supported a 2-s improvement in the timed up and go test and a 34% improvement in rapid isometric knee extension contractions in the exercise group but not in controls. Central neural adaptations are suggested because this lower extremity exercise program also elicited significant improvements in the untrained upper extremities of the exercise group (elbow extension rate of force development scaling factor and Nine-Hole Peg Test, P < 0.05). CONCLUSION These results demonstrate that a relatively low dose of speed-based exercise can improve neuromuscular function and tests of mobility in older adults. Such a program serves as a sensible precursor to subsequent, more vigorous training or as an adjunct to a program where a velocity emphasis is lacking.
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Affiliation(s)
- Maria Bellumori
- 1Department of Kinesiology, California State University, Monterey Bay, Seaside, CA; 2Department of Health and Exercise Sciences, Rowan University, Glassboro, NJ; and 3Department of Kinesiology and Applied Physiology, University of Delaware, Newark, DE
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54
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Brocca L, McPhee JS, Longa E, Canepari M, Seynnes O, De Vito G, Pellegrino MA, Narici M, Bottinelli R. Structure and function of human muscle fibres and muscle proteome in physically active older men. J Physiol 2017; 595:4823-4844. [PMID: 28452077 DOI: 10.1113/jp274148] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/21/2017] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Loss of muscle mass and strength in the growing population of elderly people is a major health concern for modern societies. This condition, termed sarcopenia, is a major cause of falls and of the subsequent increase in morbidity and mortality. Despite numerous studies on the impact of ageing on individual muscle fibres, the contribution of single muscle fibre adaptations to ageing-induced atrophy and functional impairment is still unsettled. The level of physical function and disuse is often associated with ageing. We studied relatively healthy older adults in order to understand the effects of ageing per se without the confounding impact of impaired physical function. We found that in healthy ageing, structural and functional alterations of muscle fibres occur. Protein post-translational modifications, oxidation and phosphorylation contribute to such alterations more than loss of myosin and other muscle protein content. ABSTRACT Contradictory results have been reported on the impact of ageing on structure and functions of skeletal muscle fibres, likely to be due to a complex interplay between ageing and other phenomena such as disuse and diseases. Here we recruited healthy, physically and socially active young (YO) and elderly (EL) men in order to study ageing per se without the confounding effects of impaired physical function. In vivo analyses of quadriceps and in vitro analyses of vastus lateralis muscle biopsies were performed. In EL subjects, our results show that (i) quadriceps volume, maximum voluntary contraction isometric torque and patellar tendon force were significantly lower; (ii) muscle fibres went through significant atrophy and impairment of specific force (isometric force/cross-sectional area) and unloaded shortening velocity; (iii) myosin/actin ratio and myosin content in individual muscle fibres were not altered; (iv) the muscle proteome went through quantitative adaptations, namely an up-regulation of the content of several groups of proteins among which were myofibrillar proteins and antioxidant defence systems; (v) the muscle proteome went through qualitative adaptations, namely phosphorylation of several proteins, including myosin light chain-2 slow and troponin T and carbonylation of myosin heavy chains. The present results indicate that impairment of individual muscle fibre structure and function is a major feature of ageing per se and that qualitative adaptations of muscle proteome are likely to be more involved than quantitative adaptations in determining such a phenomenon.
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Affiliation(s)
- Lorenza Brocca
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interuniversity Institute of Myology, University of Pavia, Pavia, Italy
| | - Jamie S McPhee
- School of Healthcare Science, Manchester Metropolitan University, Manchester, UK
| | - Emanuela Longa
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Monica Canepari
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interuniversity Institute of Myology, University of Pavia, Pavia, Italy
| | - Olivier Seynnes
- Department of Physical Performance, Norwegian School of Sport Sciences, Oslo, Norway
| | - Giuseppe De Vito
- Institute for Sport and Health, University College Dublin, Ireland
| | - Maria Antonietta Pellegrino
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interuniversity Institute of Myology, University of Pavia, Pavia, Italy.,Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia, Italy
| | - Marco Narici
- School of Graduate Entry to Medicine and Health, Division of Clinical Physiology, University of Nottingham, Derby, UK
| | - Roberto Bottinelli
- Department of Molecular Medicine, University of Pavia, Pavia, Italy.,Interdipartimental Centre for Biology and Sport Medicine, University of Pavia, Pavia, Italy.,Fondazione Salvatore Maugeri (IRCCS), Scientific Institute of Pavia, Pavia, Italy
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55
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Nonlinear Trimodal Regression Analysis of Radiodensitometric Distributions to Quantify Sarcopenic and Sequelae Muscle Degeneration. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2016; 2016:8932950. [PMID: 28115982 PMCID: PMC5223076 DOI: 10.1155/2016/8932950] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 11/30/2016] [Accepted: 12/07/2016] [Indexed: 12/12/2022]
Abstract
Muscle degeneration has been consistently identified as an independent risk factor for high mortality in both aging populations and individuals suffering from neuromuscular pathology or injury. While there is much extant literature on its quantification and correlation to comorbidities, a quantitative gold standard for analyses in this regard remains undefined. Herein, we hypothesize that rigorously quantifying entire radiodensitometric distributions elicits more muscle quality information than average values reported in extant methods. This study reports the development and utility of a nonlinear trimodal regression analysis method utilized on radiodensitometric distributions of upper leg muscles from CT scans of a healthy young adult, a healthy elderly subject, and a spinal cord injury patient. The method was then employed with a THA cohort to assess pre- and postsurgical differences in their healthy and operative legs. Results from the initial representative models elicited high degrees of correlation to HU distributions, and regression parameters highlighted physiologically evident differences between subjects. Furthermore, results from the THA cohort echoed physiological justification and indicated significant improvements in muscle quality in both legs following surgery. Altogether, these results highlight the utility of novel parameters from entire HU distributions that could provide insight into the optimal quantification of muscle degeneration.
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56
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Discrepancies between Skinned Single Muscle Fibres and Whole Thigh Muscle Function Characteristics in Young and Elderly Human Subjects. BIOMED RESEARCH INTERNATIONAL 2016; 2016:6206959. [PMID: 28070513 PMCID: PMC5192307 DOI: 10.1155/2016/6206959] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 09/19/2016] [Accepted: 11/02/2016] [Indexed: 12/25/2022]
Abstract
We aimed to analyse the mechanical properties of skinned single muscle fibres derived from the vastus lateralis (VL) muscle in relation to those of the whole intact thigh muscle and to compare any difference between young and older adults. Sixteen young men (29.25 ± 4.65 years), 11 older men (71.45 ± 2.94 years), 11 young women (29.64 ± 4.88 years), and 7 older women (67.29 ± 1.70 years) were recruited. In vivo analyses were performed for mechanical properties such as isokinetic performance, isometric torque, and power. Specific force and maximum shortening velocity (Vo) were measured with single muscle fibres. Sex difference showed greater impact on the functional properties of both the whole muscle (p < 0.01) and single muscle fibres than aging (p < 0.05). Sex difference, rather than aging, yielded more remarkable differences in gross mechanical properties in the single muscle fibre study in which significant differences between young men and young women were found only in the cross-sectional area and Vo (p < 0.05). Age and sex differences reflect the mechanical properties of both single muscle fibres and whole thigh muscle, with the whole muscle yielding more prominent functional properties.
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57
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Hunter SK, Pereira HM, Keenan KG. The aging neuromuscular system and motor performance. J Appl Physiol (1985) 2016; 121:982-995. [PMID: 27516536 PMCID: PMC5142309 DOI: 10.1152/japplphysiol.00475.2016] [Citation(s) in RCA: 226] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/08/2016] [Indexed: 12/25/2022] Open
Abstract
Age-related changes in the basic functional unit of the neuromuscular system, the motor unit, and its neural inputs have a profound effect on motor function, especially among the expanding number of old (older than ∼60 yr) and very old (older than ∼80 yr) adults. This review presents evidence that age-related changes in motor unit morphology and properties lead to impaired motor performance that includes 1) reduced maximal strength and power, slower contractile velocity, and increased fatigability; and 2) increased variability during and between motor tasks, including decreased force steadiness and increased variability of contraction velocity and torque over repeat contractions. The age-related increase in variability of motor performance with aging appears to involve reduced and more variable synaptic inputs that drive motor neuron activation, fewer and larger motor units, less stable neuromuscular junctions, lower and more variable motor unit action potential discharge rates, and smaller and slower skeletal muscle fibers that coexpress different myosin heavy chain isoforms in the muscle of older adults. Physical activity may modify motor unit properties and function in old men and women, although the effects on variability of motor performance are largely unknown. Many studies are of cross-sectional design, so there is a tremendous opportunity to perform high-impact and longitudinal studies along the continuum of aging that determine 1) the influence and cause of the increased variability with aging on functional performance tasks, and 2) whether lifestyle factors such as physical exercise can minimize this age-related variability in motor performance in the rapidly expanding numbers of very old adults.
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Affiliation(s)
- Sandra K Hunter
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Hugo M Pereira
- Exercise Science Program, Department of Physical Therapy, Marquette University, Milwaukee, Wisconsin; and
| | - Kevin G Keenan
- Department of Kinesiology, College of Health Sciences, University of Wisconsin, Milwaukee, Wisconsin
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58
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Grosicki GJ, Standley RA, Murach KA, Raue U, Minchev K, Coen PM, Newman AB, Cummings S, Harris T, Kritchevsky S, Goodpaster BH, Trappe S. Improved single muscle fiber quality in the oldest-old. J Appl Physiol (1985) 2016; 121:878-884. [PMID: 27516537 DOI: 10.1152/japplphysiol.00479.2016] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 08/04/2016] [Indexed: 01/06/2023] Open
Abstract
We examined single muscle fiber contractile function of the oldest-old (3F/2M, 89 ± 1 yr old) enrolled in The Health, Aging, and Body Composition Study (The Health ABC Study). Vastus lateralis muscle biopsies were obtained and single muscle fiber function was determined (n = 105) prior to myosin heavy chain (MHC) isoform identification with sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Cross-sectional area of MHC I muscle fibers (5,576 ± 333 μm2; n = 58) was 21% larger (P < 0.05) than MHC IIa fibers (4,518 ± 386 μm2; n = 47). Normalized power (an indicator of muscle fiber quality incorporating size, strength, and speed) of MHC I and IIa muscle fibers was 2.3 ± 0.1 and 17.4 ± 0.8 W/l, respectively. Compared with previous research from our lab using identical procedures, MHC I normalized power was 28% higher than healthy 20 yr olds and similar to younger octogenarians (∼80 yr old). Normalized power of MHC IIa fibers was 63% greater than 20 yr olds and 39% greater than younger octogenarians. These comparative data suggest that power output per unit size (i.e., muscle quality) of remaining muscle fibers improves with age, a phenomenon more pronounced in MHC IIa fibers. Age-related single muscle fiber quality improvements may be a compensatory mechanism to help offset decrements in whole muscle function.
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Affiliation(s)
- Greg J Grosicki
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Robert A Standley
- Translational Research Institute for Metabolism and Diabetes, Orlando, Florida
| | - Kevin A Murach
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Ulrika Raue
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Kiril Minchev
- Human Performance Laboratory, Ball State University, Muncie, Indiana
| | - Paul M Coen
- Translational Research Institute for Metabolism and Diabetes, Orlando, Florida
| | - Anne B Newman
- Center for Aging and Population Health, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Steven Cummings
- California Pacific Medical Center Research Institute, San Francisco, California
| | - Tamara Harris
- Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, Maryland; and
| | - Stephen Kritchevsky
- Sticht Center on Aging, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Bret H Goodpaster
- Translational Research Institute for Metabolism and Diabetes, Orlando, Florida
| | - Scott Trappe
- Human Performance Laboratory, Ball State University, Muncie, Indiana;
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59
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Gregorich ZR, Peng Y, Cai W, Jin Y, Wei L, Chen AJ, McKiernan SH, Aiken JM, Moss RL, Diffee GM, Ge Y. Top-Down Targeted Proteomics Reveals Decrease in Myosin Regulatory Light-Chain Phosphorylation That Contributes to Sarcopenic Muscle Dysfunction. J Proteome Res 2016; 15:2706-16. [PMID: 27362462 PMCID: PMC4975644 DOI: 10.1021/acs.jproteome.6b00244] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Sarcopenia, the loss of skeletal muscle mass and function with advancing age, is a significant cause of disability and loss of independence in the elderly and thus, represents a formidable challenge for the aging population. Nevertheless, the molecular mechanism(s) underlying sarcopenia-associated muscle dysfunction remain poorly understood. In this study, we employed an integrated approach combining top-down targeted proteomics with mechanical measurements to dissect the molecular mechanism(s) in age-related muscle dysfunction. Top-down targeted proteomic analysis uncovered a progressive age-related decline in the phosphorylation of myosin regulatory light chain (RLC), a critical protein involved in the modulation of muscle contractility, in the skeletal muscle of aging rats. Top-down tandem mass spectrometry analysis identified a previously unreported bis-phosphorylated proteoform of fast skeletal RLC and localized the sites of decreasing phosphorylation to Ser14/15. Of these sites, Ser14 phosphorylation represents a previously unidentified site of phosphorylation in RLC from fast-twitch skeletal muscle. Subsequent mechanical analysis of single fast-twitch fibers isolated from the muscles of rats of different ages revealed that the observed decline in RLC phosphorylation can account for age-related decreases in the contractile properties of sarcopenic fast-twitch muscles. These results strongly support a role for decreasing RLC phosphorylation in sarcopenia-associated muscle dysfunction and suggest that therapeutic modulation of RLC phosphorylation may represent a new avenue for the treatment of sarcopenia.
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Affiliation(s)
- Zachery R. Gregorich
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Ying Peng
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Wenxuan Cai
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Yutong Jin
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706
| | - Liming Wei
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Institutes of Biomedical Sciences, Fudan University, Shanghai, 200032, P. R. China
| | - Albert J. Chen
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Susan H. McKiernan
- Department of Kinesiology, University of Wisconsin-Madison, 2000 Observatory Dr., Madison, WI, 53705
| | - Judd M. Aiken
- Departments of Agriculture, Food, and Nutritional Sciences, University of Alberta-Edmonton, Edmonton, AB, Canada
| | - Richard L. Moss
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- UW Cardiovascular Research Center, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Gary M. Diffee
- Department of Kinesiology, University of Wisconsin-Madison, 2000 Observatory Dr., Madison, WI, 53705
- UW Cardiovascular Research Center, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
| | - Ying Ge
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI, 53706
- Human Proteomics Program, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
- UW Cardiovascular Research Center, University of Wisconsin-Madison, 1111 Highland Ave., Madison, WI, 53705
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60
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Liu JX, Eriksson PO, Thornell LE, Pedrosa-Domellöf F. Fiber Content and Myosin Heavy Chain Composition of Muscle Spindles in Aged Human Biceps Brachii. J Histochem Cytochem 2016; 53:445-54. [PMID: 15805419 DOI: 10.1369/jhc.4a6257.2005] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study investigated potential age-related changes in human muscle spindles with respect to the intrafusal fiber-type content and myosin heavy chain (MyHC) composition in biceps brachii muscle. The total number of intrafusal fibers per spindle decreased significantly with aging, due to a significant reduction in the number of nuclear chain fibers. Nuclear chain fibers in old spindles were short and some showed novel expression of MyHC α-cardiac. The expression of MyHC α-cardiac in bag1and bag2fibers was greatly decreased in the A region. The expression of slow MyHC was increased in nuclear bag1fibers and that of fetal MyHC decreased in bag2fibers whereas the patterns of distribution of the remaining MyHC isoforms were generally not affected by aging. We conclude that aging appears to have an important impact on muscle spindle composition. These changes in muscle spindle phenotype may reflect an age-related deterioration in sensory and motor innervation and are likely to have an impact in motor control in the elderly.
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Affiliation(s)
- Jing-Xia Liu
- Department of Integrative Medical Biology, Section for Anatomy, Umeå University, Umeå, Sweden
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61
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Lim JY. Therapeutic potential of eccentric exercises for age-related muscle atrophy. Integr Med Res 2016; 5:176-181. [PMID: 28462115 PMCID: PMC5390411 DOI: 10.1016/j.imr.2016.06.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 06/14/2016] [Accepted: 06/14/2016] [Indexed: 02/04/2023] Open
Abstract
Recent studies have focused on evidence-based interventions to prevent mobility decline and enhance physical performance in older adults. Several modalities, in addition to traditional strengthening programs, have been designed to manage age-related functional decline more effectively. In this study, we reviewed the current relevant literatures to assess the therapeutic potential of eccentric exercises for age-related muscle atrophy (sarcopenia). Age-related changes in human skeletal muscle, and their relationship with physical performance, are discussed with reference to in vitro physiologic and human biomechanics studies. An overview of issues relevant to sarcopenia is provided in the context of the recent consensus on the diagnosis and management of the condition. A decline in mobility among the aging population is closely linked with changes in the muscle force-velocity relationship. Interventions based specifically on increasing velocity and eccentric strength can improve function more effectively compared with traditional strengthening programs. Eccentric strengthening programs are introduced as a specific method for improving both muscle force and velocity. To be more effective, exercise interventions for older adults should focus on enhancing the muscle force-velocity relationship. Exercises that can be performed easily, and that utilize eccentric strength (which is relatively spared during the aging process), are needed to improve both muscle force and velocity.
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Affiliation(s)
- Jae-Young Lim
- Department of Rehabilitation Medicine, Mechanic and Molecular Myology Laboratory, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam, Republic of Korea
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62
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Choi SJ. Age-related functional changes and susceptibility to eccentric contraction-induced damage in skeletal muscle cell. Integr Med Res 2016; 5:171-175. [PMID: 28462114 PMCID: PMC5390413 DOI: 10.1016/j.imr.2016.05.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/12/2016] [Accepted: 05/12/2016] [Indexed: 01/30/2023] Open
Abstract
Depending upon external loading conditions, skeletal muscles can either shorten, lengthen, or remain at a fixed length as they produce force. Fixed-end or isometric contractions stabilize joints and allow muscles to act as active struts during locomotion. Active muscles dissipate energy when they are lengthened by an external force that exceeds their current force producing capacity. These unaccustomed eccentric activities often lead to muscle weakness, soreness, and inflammation. During aging, the ability to produce force under these conditions is reduced and appears to be due to not only reductions in muscle mass but also to alterations in the basic mechanisms of contraction. These alterations include impairments in the excitation–contraction process, and the action of the cross-bridges. Also, it is well known that age-related skeletal muscle atrophy is characterized by a preferential atrophy of fast fibers, and increased susceptibility to fast muscle fiber when aged muscles are exposed to eccentric contraction followed by the impaired recovery process has been reported. Taken together, the selective loss of fast muscle fiber in aged muscle could be affected by eccentric-induced muscle damage, which has significant implication to identify the etiology of the age-related functional changes. Therefore, in this review the alteration of age-related muscle function and its impact to/of eccentric induced muscle damage and recovery will be addressed in detail.
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Affiliation(s)
- Seung-Jun Choi
- Division of Sports and Health Science, College of Art, Kyungsung University, 309 Suyeong-ro, Nam-Gu, Busan 48434, Republic of Korea.
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Maffiuletti NA, Aagaard P, Blazevich AJ, Folland J, Tillin N, Duchateau J. Rate of force development: physiological and methodological considerations. Eur J Appl Physiol 2016; 116:1091-116. [PMID: 26941023 PMCID: PMC4875063 DOI: 10.1007/s00421-016-3346-6] [Citation(s) in RCA: 761] [Impact Index Per Article: 95.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 02/17/2016] [Indexed: 11/26/2022]
Abstract
The evaluation of rate of force development during rapid contractions has recently become quite popular for characterising explosive strength of athletes, elderly individuals and patients. The main aims of this narrative review are to describe the neuromuscular determinants of rate of force development and to discuss various methodological considerations inherent to its evaluation for research and clinical purposes. Rate of force development (1) seems to be mainly determined by the capacity to produce maximal voluntary activation in the early phase of an explosive contraction (first 50–75 ms), particularly as a result of increased motor unit discharge rate; (2) can be improved by both explosive-type and heavy-resistance strength training in different subject populations, mainly through an improvement in rapid muscle activation; (3) is quite difficult to evaluate in a valid and reliable way. Therefore, we provide evidence-based practical recommendations for rational quantification of rate of force development in both laboratory and clinical settings.
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Affiliation(s)
- Nicola A Maffiuletti
- Human Performance Lab, Schulthess Clinic, Lengghalde 6, 8008, Zurich, Switzerland.
| | - Per Aagaard
- Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster (SMRC), University of Southern Denmark, Odense, Denmark
| | - Anthony J Blazevich
- Centre for Exercise and Sports Science Research (CESSR), School of Medical and Health Sciences, Edith Cowan University, Joondalup, Australia
| | - Jonathan Folland
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK
| | - Neale Tillin
- Department of Life Sciences, University of Roehampton, London, UK
| | - Jacques Duchateau
- Laboratory of Applied Biology, ULB Neurosciences Institute, Université Libre de Bruxelles (ULB), Brussels, Belgium
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Melo RC, Takahashi AC, Quitério RJ, Salvini TF, Catai AM. Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults. J Strength Cond Res 2016; 30:259-66. [DOI: 10.1519/jsc.0000000000001047] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Leyva A, Balachandran A, Signorile JF. Lower-Body Torque and Power Declines Across Six Decades in Three Hundred Fifty-Seven Men and Women. J Strength Cond Res 2016; 30:141-58. [DOI: 10.1519/jsc.0000000000001083] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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66
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Defining Spino-Pelvic Alignment Thresholds: Should Operative Goals in Adult Spinal Deformity Surgery Account for Age? Spine (Phila Pa 1976) 2016; 41:62-8. [PMID: 26689395 DOI: 10.1097/brs.0000000000001171] [Citation(s) in RCA: 257] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Retrospective review of prospective, multicenter database. OBJECTIVE The aim of the study was to determine age-specific spino-pelvic parameters, to extrapolate age-specific Oswestry Disability Index (ODI) values from published Short Form (SF)-36 Physical Component Score (PCS) data, and to propose age-specific realignment thresholds for adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA The Scoliosis Research Society-Schwab classification offers a framework for defining alignment in patients with ASD. Although age-specific changes in spinal alignment and patient-reported outcomes have been established in the literature, their relationship in the setting of ASD operative realignment has not been reported. METHODS ASD patients who received operative or nonoperative treatment were consecutively enrolled. Patients were stratified by age, consistent with published US-normative values (Norms) of the SF-36 PCS (<35, 35-44, 45-54, 55-64, 65-74, >75 y old). At baseline, relationships between between radiographic spino-pelvic parameters (lumbar-pelvic mismatch [PI-LL], pelvic tilt [PT], sagittal vertical axis [SVA], and T1 pelvic angle [TPA]), age, and PCS were established using linear regression analysis; normative PCS values were then used to establish age-specific targets. Correlation analysis with ODI and PCS was used to determine age-specific ideal alignment. RESULTS Baseline analysis included 773 patients (53.7 y old, 54% operative, 83% female). There was a strong correlation between ODI and PCS (r = 0.814, P < 0.001), allowing for the extrapolation of US-normative ODI by age group. Linear regression analysis (all with r > 0.510, P < 0.001) combined with US-normative PCS values demonstrated that ideal spino-pelvic values increased with age, ranging from PT = 10.9 degrees, PI-LL = -10.5 degrees, and SVA = 4.1 mm for patients under 35 years to PT = 28.5 degrees, PI-LL = 16.7 degrees, and SVA = 78.1 mm for patients over 75 years. Clinically, older patients had greater compensation, more degenerative loss of lordosis, and were more pitched forward. CONCLUSION This study demonstrated that sagittal spino-pelvic alignment varies with age. Thus, operative realignment targets should account for age, with younger patients requiring more rigorous alignment objectives.
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Barikroo A, Berretin-Felix G, Carnaby G, Crary M. Effect of transcutaneous electrical stimulation amplitude on timing of swallow pressure peaks between healthy young and older adults. Gerodontology 2015; 34:24-32. [PMID: 26694095 DOI: 10.1111/ger.12221] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/30/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVES This study compared the effect of transcutaneous electrical stimulation (TES) amplitude on timing of lingual-palatal and pharyngeal peak pressures during swallowing in healthy younger and older adults. BACKGROUND Transcutaneous electrical stimulation amplitude is one parameter that may have different impacts on the neuromotor system and swallowing physiology. One aspect of swallowing physiology influenced by age is the timing of swallowing events. However, the effect of varying TES amplitudes on timing of swallowing physiology is poorly understood, especially in older adults. MATERIALS AND METHODS Thirty-four adults (20 younger and 14 older) swallowed 10 ml of nectar-thick liquid under three TES conditions: no stimulation, low-amplitude stimulation and high-amplitude stimulation. TES was delivered by surface electrodes on the anterior neck. Timing of pressure peaks for lingual-palatal contacts and pharyngeal pressures were measured under each condition. RESULTS A significant age × stimulation amplitude interaction was identified for the base of tongue (BOT) [F(2,62) = 5.087, p < 0.009] and the hypopharynx (HYPO) [F(2,62) = 3.277, p < 0.044]. At the BOT, low-amplitude TES resulted in slower swallows in the younger adults compared with no TES. In older adults, low-amplitude TES resulted in faster swallows compared with high-amplitude TES. At the HYPO, no significant differences were identified in pressure timing across the three TES amplitudes in both age groups. In each case, low-amplitude TES resulted in faster swallows in older adults compared with younger adults. CONCLUSIONS Transcutaneous electrical stimulation influences pharyngeal pressure timing differently in young and old people, which questions the appropriateness of using a 'one-size-fits-all' TES amplitude for rehabilitating people with dysphagia.
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Affiliation(s)
- Ali Barikroo
- Department of Speech, Language and Hearing Sciences, University of Florida, Gainesville, FL, USA
| | - Giedré Berretin-Felix
- Speech Pathology/Audiology Department, Bauru Dental School, University of São Paulo, Bauru, SP, Brazil
| | - Giselle Carnaby
- Swallowing Research Laboratory, Department of Communication Sciences and Disorders, University of Central Florida, Orlando, FL, USA
| | - Michael Crary
- Swallowing Research Laboratory, Department of Communication Sciences and Disorders, University of Central Florida, Orlando, FL, USA
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Power GA, Minozzo FC, Spendiff S, Filion ME, Konokhova Y, Purves-Smith MF, Pion C, Aubertin-Leheudre M, Morais JA, Herzog W, Hepple RT, Taivassalo T, Rassier DE. Reduction in single muscle fiber rate of force development with aging is not attenuated in world class older masters athletes. Am J Physiol Cell Physiol 2015; 310:C318-27. [PMID: 26632598 DOI: 10.1152/ajpcell.00289.2015] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 11/20/2015] [Indexed: 12/25/2022]
Abstract
Normal adult aging is associated with impaired muscle contractile function; however, to what extent cross-bridge kinetics are altered in aging muscle is not clear. We used a slacken restretch maneuver on single muscle fiber segments biopsied from the vastus lateralis of young adults (∼23 yr), older nonathlete (NA) adults (∼80 yr), and age-matched world class masters athletes (MA; ∼80 yr) to assess the rate of force redevelopment (ktr) and cross-bridge kinetics. A post hoc analysis was performed, and only the mechanical properties of "slow type" fibers based on unloaded shortening velocity (Vo) measurements are reported. The MA and NA were ∼54 and 43% weaker, respectively, for specific force compared with young. Similarly, when force was normalized to cross-sectional area determined via the fiber shape angularity data, both old groups did not differ, and the MA and NA were ∼43 and 48% weaker, respectively, compared with young (P < 0.05). Vo for both MA and NA old groups was 62 and 46% slower, respectively, compared with young. Both MA and NA adults had approximately two times slower values for ktr compared with young. The slower Vo in both old groups relative to young, coupled with a similarly reduced ktr, suggests impaired cross-bridge kinetics are responsible for impaired single fiber contractile properties with aging. These results challenge the widely accepted resilience of slow type fibers to cellular aging.
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Affiliation(s)
- Geoffrey A Power
- Department of Human Health and Nutritional Sciences, College of Biological Sciences, University of Guelph, Guelph, Ontario, Canada; Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada;
| | - Fábio C Minozzo
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada; The Muscle Physiology and Biophysics Laboratory, McGill University, Montreal, Quebec, Canada
| | - Sally Spendiff
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Marie-Eve Filion
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Yana Konokhova
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Maddy F Purves-Smith
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Charlotte Pion
- Département de Kinanthropologie, Université du Québec a' Montréal, Montreal, Quebec, Canada
| | | | - José A Morais
- Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Walter Herzog
- Faculty of Kinesiology, Human Performance Laboratory, University of Calgary, Calgary, Alberta, Canada
| | - Russell T Hepple
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada; Department of Medicine, McGill University, Montreal, Quebec, Canada; Meakins Christie Laboratories, McGill University, Montreal, Quebec, Canada; and
| | - Tanja Taivassalo
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada
| | - Dilson E Rassier
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada; The Muscle Physiology and Biophysics Laboratory, McGill University, Montreal, Quebec, Canada; Meakins Christie Laboratories, McGill University, Montreal, Quebec, Canada; and Department of Physics, McGill University, Montreal, Quebec, Canada
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Callahan DM, Tourville TW, Slauterbeck JR, Ades PA, Stevens-Lapsley J, Beynnon BD, Toth MJ. Reduced rate of knee extensor torque development in older adults with knee osteoarthritis is associated with intrinsic muscle contractile deficits. Exp Gerontol 2015; 72:16-21. [PMID: 26343257 PMCID: PMC4654635 DOI: 10.1016/j.exger.2015.08.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 07/21/2015] [Accepted: 08/10/2015] [Indexed: 11/17/2022]
Abstract
We examined the effect of knee osteoarthritis on the rate of torque development (RTD) of the knee extensors in older adults with advanced-stage knee osteoarthritis (OA; n=15) and recreationally-active controls (n=15) of similar age, sex and health status, as well as the relationship between RTD and the size and contractility of single muscle fibers. OA participants had lower RTD when expressed in absolute terms (Nm/ms). There were sex differences in peak RTD (P<0.05), with greater RTD in men, but no group by sex interaction effects for any variables. The lower RTD in OA versus controls was not explained by variation between groups in the fiber type admixture of the muscle, and was mitigated when RTD was normalized to peak torque (PT). In knee OA volunteers, we found strong correlations between the RTD expressed relative to PT and the velocity of contraction of single myosin heavy chain (MHC) I and IIA/X muscle fibers (r=0.652 and 0.862; both P<0.05) and power output of MHC I fibers (r=0.642; P<0.05). In controls, RTD relative to PT was related to fiber cross-sectional area of MHC IIA/X fibers (r=0.707; P<0.05), but not measures of single fiber contractile performance. To our knowledge, these results represent the first demonstration that variation in whole muscle contractile kinetics in patients with advanced-stage knee osteoarthritis and healthy older adults is related, in part, to the size and function of single muscle fibers.
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Affiliation(s)
- Damien M Callahan
- Department of Medicine, University of Vermont, College of Medicine, Burlington, VT, United States
| | - Timothy W Tourville
- Department of Orthopaedics and Rehabilitation, University of Vermont, College of Medicine, Burlington, VT, United States
| | - James R Slauterbeck
- Department of Orthopaedics and Rehabilitation, University of Vermont, College of Medicine, Burlington, VT, United States
| | - Philip A Ades
- Department of Medicine, University of Vermont, College of Medicine, Burlington, VT, United States
| | - Jennifer Stevens-Lapsley
- Department of Physical Medicine and Rehabilitation, University of Colorado, Denver, CO, United States
| | - Bruce D Beynnon
- Department of Orthopaedics and Rehabilitation, University of Vermont, College of Medicine, Burlington, VT, United States
| | - Michael J Toth
- Department of Medicine, University of Vermont, College of Medicine, Burlington, VT, United States; Department of Orthopaedics and Rehabilitation, University of Vermont, College of Medicine, Burlington, VT, United States; Department of Molecular Physiology and Biophysics, University of Vermont, College of Medicine, Burlington, VT, United States.
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Venturelli M, Saggin P, Muti E, Naro F, Cancellara L, Toniolo L, Tarperi C, Calabria E, Richardson RS, Reggiani C, Schena F. In vivo and in vitro evidence that intrinsic upper- and lower-limb skeletal muscle function is unaffected by ageing and disuse in oldest-old humans. Acta Physiol (Oxf) 2015; 215:58-71. [PMID: 25965867 DOI: 10.1111/apha.12524] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 02/06/2015] [Accepted: 05/07/2015] [Indexed: 12/17/2022]
Abstract
AIM To parse out the impact of advanced ageing and disuse on skeletal muscle function, we utilized both in vivo and in vitro techniques to comprehensively assess upper- and lower-limb muscle contractile properties in 8 young (YG; 25 ± 6 years) and 8 oldest-old mobile (OM; 87 ± 5 years) and 8 immobile (OI; 88 ± 4 years) women. METHODS In vivo, maximal voluntary contraction (MVC), electrically evoked resting twitch force (RT), and physiological cross-sectional area (PCSA) of the quadriceps and elbow flexors were assessed. Muscle biopsies of the vastus lateralis and biceps brachii facilitated the in vitro assessment of single fibre-specific tension (Po). RESULTS In vivo, compared to the young, both the OM and OI exhibited a more pronounced loss of MVC in the lower limb [OM (-60%) and OI (-75%)] than the upper limb (OM = -51%; OI = -47%). Taking into account the reduction in muscle PCSA (OM = -10%; OI = -18%), only evident in the lower limb, by calculating voluntary muscle-specific force, the lower limb of the OI (-40%) was more compromised than the OM (-13%). However, in vivo, RT in both upper and lower limbs (approx. 9.8 N m cm(-2) ) and Po (approx. 123 mN mm(-2) ), assessed in vitro, implies preserved intrinsic contractile function in all muscles of the oldest-old and were well correlated (r = 0.81). CONCLUSION These findings suggest that in the oldest-old, neither advanced ageing nor disuse, per se, impacts intrinsic skeletal muscle function, as assessed in vitro. However, in vivo, muscle function is attenuated by age and exacerbated by disuse, implicating factors other than skeletal muscle, such as neuromuscular control, in this diminution of function.
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Affiliation(s)
- M. Venturelli
- Department of Biomedical Sciences for Health; University of Milan; Milan Italy
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - P. Saggin
- Division of Radiology and Imaging; City of Verona Diagnostic Center; Verona Italy
| | - E. Muti
- Mons. Mazzali Foundation; Mantova Italy
| | - F. Naro
- DAHFMO Unit of Histology and Medical Embryology; Sapienza University; Rome Italy
| | - L. Cancellara
- Department of Biomedical Sciences; University of Padova; Padova Italy
| | - L. Toniolo
- Department of Biomedical Sciences; University of Padova; Padova Italy
| | - C. Tarperi
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - E. Calabria
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
| | - R. S. Richardson
- Division of Geriatrics; Department of Internal Medicine; University of Utah School of Medicine; Salt Lake City UT USA
- Geriatric Research, Education, and Clinical Center; George E. Wahlen Department of Veterans Affairs Medical Center; Salt Lake City UT USA
- Department of Exercise and Sport Science; University of Utah; Salt Lake City UT USA
| | - C. Reggiani
- Department of Biomedical Sciences; University of Padova; Padova Italy
- CNR (Consiglio Nazionale delle Ricerche); Institute of Neuroscience; Padua Italy
| | - F. Schena
- Department of Neurological, and Movement Sciences; University of Verona; Verona Italy
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Curtin NA, Diack RA, West TG, Wilson AM, Woledge RC. Skinned fibres produce the same power and force as intact fibre bundles from muscle of wild rabbits. ACTA ACUST UNITED AC 2015. [PMID: 26206354 DOI: 10.1242/jeb.121897] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Skinned fibres have advantages for comparing the muscle properties of different animal species because they can be prepared from a needle biopsy taken under field conditions. However, it is not clear how well the contractile properties of skinned fibres reflect the properties of the muscle fibres in vivo. Here, we compare the mechanical performance of intact fibre bundles and skinned fibres from muscle of the same animals. This is the first such direct comparison. Maximum power and isometric force were measured at 25 °C using peroneus longus (PL) and extensor digiti-V (ED-V) muscles from wild rabbits (Oryctolagus cuniculus). More than 90% of the fibres in these muscles are fast-twitch, type 2 fibres. Maximum power was measured in force-clamp experiments. We show that maximum power per volume was the same in intact (121.3 ± 16.1 W l(-1), mean ± s.e.m.; N=16) and skinned (122.6 ± 4.6 W l(-1); N=141) fibres. Maximum relative power (power/F(IM) Lo, where F(IM) is maximum isometric force and Lo is standard fibre length) was also similar in intact (0.645 ± 0.037; N=16) and skinned (0.589 ± 0.019; N=141) fibres. Relative power is independent of volume and thus not subject to errors in measurement of volume. Finally, maximum isometric force per cross-sectional area was also found to be the same for intact and skinned fibres (181.9 kPa ± 19.1; N=16; 207.8 kPa ± 4.8; N=141, respectively). These results contrast with previous measurements of performance at lower temperatures where skinned fibres produce much less power than intact fibres from both mammals and non-mammalian species.
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Affiliation(s)
- Nancy A Curtin
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK National Heart and Lung Institute, Imperial College London, London SW7 2AZ, UK
| | - Rebecca A Diack
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Timothy G West
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Alan M Wilson
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Roger C Woledge
- Structure and Motion Laboratory, Royal Veterinary College, University of London, Hawkshead Lane, Hatfield AL9 7TA, UK
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Lourenço Dos Santos S, Baraibar MA, Lundberg S, Eeg-Olofsson O, Larsson L, Friguet B. Oxidative proteome alterations during skeletal muscle ageing. Redox Biol 2015; 5:267-274. [PMID: 26073261 PMCID: PMC4475901 DOI: 10.1016/j.redox.2015.05.006] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 05/21/2015] [Accepted: 05/29/2015] [Indexed: 01/06/2023] Open
Abstract
Sarcopenia corresponds to the degenerative loss of skeletal muscle mass, quality, and strength associated with ageing and leads to a progressive impairment of mobility and quality of life. However, the cellular and molecular mechanisms involved in this process are not completely understood. A hallmark of cellular and tissular ageing is the accumulation of oxidatively modified (carbonylated) proteins, leading to a decreased quality of the cellular proteome that could directly impact on normal cellular functions. Although increased oxidative stress has been reported during skeletal muscle ageing, the oxidized protein targets, also referred as to the 'oxi-proteome' or 'carbonylome', have not been characterized yet. To better understand the mechanisms by which these damaged proteins build up and potentially affect muscle function, proteins targeted by these modifications have been identified in human rectus abdominis muscle obtained from young and old healthy donors using a bi-dimensional gel electrophoresis-based proteomic approach coupled with immunodetection of carbonylated proteins. Among evidenced protein spots, 17 were found as increased carbonylated in biopsies from old donors comparing to young counterparts. These proteins are involved in key cellular functions such as cellular morphology and transport, muscle contraction and energy metabolism. Importantly, impairment of these pathways has been described in skeletal muscle during ageing. Functional decline of these proteins due to irreversible oxidation may therefore impact directly on the above-mentioned pathways, hence contributing to the generation of the sarcopenic phenotype.
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Affiliation(s)
- Sofia Lourenço Dos Santos
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing-IBPS, Paris F-75005, France; CNRS UMR-8256, Paris F-75005, France; Inserm U1164, Paris F-75005, France
| | - Martin A Baraibar
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing-IBPS, Paris F-75005, France; CNRS UMR-8256, Paris F-75005, France; Inserm U1164, Paris F-75005, France
| | - Staffan Lundberg
- Department of Women's and Children's Health, Uppsala University, Uppsala SE-751 82, Sweden
| | - Orvar Eeg-Olofsson
- Department of Women's and Children's Health, Uppsala University, Uppsala SE-751 82, Sweden
| | - Lars Larsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm SE-171 77, Sweden; Department of Clinical Neuroscience, Clinical Neurophysiology, Karolinska Institutet, Stockholm SE-171 77, Sweden
| | - Bertrand Friguet
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing-IBPS, Paris F-75005, France; CNRS UMR-8256, Paris F-75005, France; Inserm U1164, Paris F-75005, France.
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73
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Graber TG, Kim JH, Grange RW, McLoon LK, Thompson LV. C57BL/6 life span study: age-related declines in muscle power production and contractile velocity. AGE (DORDRECHT, NETHERLANDS) 2015; 37:9773. [PMID: 25893911 PMCID: PMC4401475 DOI: 10.1007/s11357-015-9773-1] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 04/01/2015] [Indexed: 05/10/2023]
Abstract
Quantification of key outcome measures in animal models of aging is an important step preceding intervention testing. One such measurement, skeletal muscle power generation (force * velocity), is critical for dynamic movement. Prior research focused on maximum power (P max), which occurs around 30-40 % of maximum load. However, movement occurs over the entire load range. Thus, the primary purpose of this study was to determine the effect of age on power generation during concentric contractions in the extensor digitorum longus (EDL) and soleus muscles over the load range from 10 to 90 % of peak isometric tetanic force (P 0). Adult, old, and elderly male C57BL/6 mice were examined for contractile function (6-7 months old, 100 % survival; ~24 months, 75 %; and ~28 months, <50 %, respectively). Mice at other ages (5-32 months) were also tested for regression modeling. We hypothesized and found that power decreased with age not only at P max but also over the load range. Importantly, we found greater age-associated deficits in both power and velocity when the muscles were contracting concentrically against heavy loads (>50 % P 0). The shape of the force-velocity curve also changed with age (a/P 0 increased). In addition, there were prolonged contraction times to maximum force and shifts in the distribution of the myosin light and heavy chain isoforms in the EDL. The results demonstrate that age-associated difficulty in movement during challenging tasks is likely due, in addition to overall reduced force output, to an accelerated deterioration of power production and contractile velocity under heavily loaded conditions.
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Affiliation(s)
- Ted G. Graber
- />Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Rm 366A Children’s Rehab Center, 426 Church Street SE, Minneapolis, MN 55455 USA
| | - Jong-Hee Kim
- />Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Rm 366A Children’s Rehab Center, 426 Church Street SE, Minneapolis, MN 55455 USA
- />Department of Physical Education, College of Performing Arts and Sport, Hanyang University, Seoul, Korea
| | - Robert W. Grange
- />Department of Human Nutrition, Foods, and Exercise, Virginia Tech University, Blacksburg, VA 24061 USA
| | - Linda K. McLoon
- />Department of Ophthalmology and Visual Neurosciences, University of Minnesota Medical School, Minneapolis, MN 55455 USA
| | - LaDora V. Thompson
- />Program in Physical Therapy, Department of Physical Medicine and Rehabilitation, University of Minnesota Medical School, Rm 366A Children’s Rehab Center, 426 Church Street SE, Minneapolis, MN 55455 USA
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Lamboley CR, Wyckelsma VL, Dutka TL, McKenna MJ, Murphy RM, Lamb GD. Contractile properties and sarcoplasmic reticulum calcium content in type I and type II skeletal muscle fibres in active aged humans. J Physiol 2015; 593:2499-514. [PMID: 25809942 DOI: 10.1113/jp270179] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 03/23/2015] [Indexed: 01/25/2023] Open
Abstract
KEY POINTS Muscle weakness in old age is due in large part to an overall loss of skeletal muscle tissue, but it remains uncertain how much also stems from alterations in the properties of the individual muscle fibres. This study examined the contractile properties and amount of stored intracellular calcium in single muscle fibres of Old (70 ± 4 years) and Young (22 ± 3 years) adults. The maximum level of force production (per unit cross-sectional area) in fast twitch fibres in Old subjects was lower than in Young subjects, and the fibres were also less sensitive to activation by calcium. The amount of calcium stored inside muscle fibres and available to trigger contraction was also lower in both fast- and slow-twitch muscle fibres in the Old subjects. These findings indicate that muscle weakness in old age stems in part from an impaired capacity for force production in the individual muscle fibres. ABSTRACT This study examined the contractile properties and sarcoplasmic reticulum (SR) Ca(2+) content in mechanically skinned vastus lateralis muscle fibres of Old (70 ± 4 years) and Young (22 ± 3 years) humans to investigate whether changes in muscle fibre properties contribute to muscle weakness in old age. In type II fibres of Old subjects, specific force was reduced by ∼17% and Ca(2+) sensitivity was also reduced (pCa50 decreased ∼0.05 pCa units) relative to that in Young. S-Glutathionylation of fast troponin I (TnIf ) markedly increased Ca(2+) sensitivity in type II fibres, but the increase was significantly smaller in Old versus Young (+0.136 and +0.164 pCa unit increases, respectively). Endogenous and maximal SR Ca(2+) content were significantly smaller in both type I and type II fibres in Old subjects. In fibres of Young, the SR could be nearly fully depleted of Ca(2+) by a combined caffeine and low Mg(2+) stimulus, whereas in fibres of Old the amount of non-releasable Ca(2+) was significantly increased (by > 12% of endogenous Ca(2+) content). Western blotting showed an increased proportion of type I fibres in Old subjects, and increased amounts of calsequestrin-2 and calsequestrin-like protein. The findings suggest that muscle weakness in old age is probably attributable in part to (i) an increased proportion of type I fibres, (ii) a reduction in both maximum specific force and Ca(2+) sensitivity in type II fibres, and also a decreased ability of S-glutathionylation of TnIf to counter the fatiguing effects of metabolites on Ca(2+) sensitivity, and (iii) a reduction in the amount of releasable SR Ca(2+) in both fibre types.
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Affiliation(s)
- C R Lamboley
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, Victoria, 8001, Australia
| | - V L Wyckelsma
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, Victoria, 8001, Australia.,La Trobe Rural Health School, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - T L Dutka
- School of Life Sciences, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - M J McKenna
- Institute of Sport, Exercise and Active Living (ISEAL), Victoria University, PO Box 14428, Melbourne, Victoria, 8001, Australia
| | - R M Murphy
- School of Molecular Sciences, La Trobe University, Melbourne, Victoria, 3086, Australia
| | - G D Lamb
- School of Life Sciences, La Trobe University, Melbourne, Victoria, 3086, Australia
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Li M, Ogilvie H, Ochala J, Artemenko K, Iwamoto H, Yagi N, Bergquist J, Larsson L. Aberrant post-translational modifications compromise human myosin motor function in old age. Aging Cell 2015; 14:228-35. [PMID: 25645586 PMCID: PMC4364835 DOI: 10.1111/acel.12307] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2014] [Indexed: 12/03/2022] Open
Abstract
Novel experimental methods, including a modified single fiber in vitro motility assay, X-ray diffraction experiments, and mass spectrometry analyses, have been performed to unravel the molecular events underlying the aging-related impairment in human skeletal muscle function at the motor protein level. The effects of old age on the function of specific myosin isoforms extracted from single human muscle fiber segments, demonstrated a significant slowing of motility speed (P < 0.001) in old age in both type I and IIa myosin heavy chain (MyHC) isoforms. The force-generating capacity of the type I and IIa MyHC isoforms was, on the other hand, not affected by old age. Similar effects were also observed when the myosin molecules extracted from muscle fibers were exposed to oxidative stress. X-ray diffraction experiments did not show any myofilament lattice spacing changes, but unraveled a more disordered filament organization in old age as shown by the greater widths of the 1, 0 equatorial reflections. Mass spectrometry (MS) analyses revealed eight age-specific myosin post-translational modifications (PTMs), in which two were located in the motor domain (carbonylation of Pro79 and Asn81) and six in the tail region (carbonylation of Asp900, Asp904, and Arg908; methylation of Glu1166; deamidation of Gln1164 and Asn1168). However, PTMs in the motor domain were only observed in the IIx MyHC isoform, suggesting PTMs in the rod region contributed to the observed disordering of myosin filaments and the slowing of motility speed. Hence, interventions that would specifically target these PTMs are warranted to reverse myosin dysfunction in old age.
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Affiliation(s)
- Meishan Li
- Department of Physiology and Pharmacology; Karolinska Institutet; SE-171 77 Stockholm Sweden
- Department of Clinical Neuroscience, Clinical Neurophysiology; Karolinska Institutet; SE-171 77 Stockholm Sweden
| | - Hannah Ogilvie
- Department of Physiology and Pharmacology; Karolinska Institutet; SE-171 77 Stockholm Sweden
- Department of Clinical Neuroscience, Clinical Neurophysiology; Karolinska Institutet; SE-171 77 Stockholm Sweden
| | - Julien Ochala
- Centre of Human and Aerospace Physiological Sciences; Faculty of Life Sciences and Medicine; King's College London; London SE1 1UL UK
| | - Konstantin Artemenko
- Analytical Chemistry; Department of Chemistry - Biomedical Centre and SciLifeLab; Uppsala University; 75124 Uppsala Sweden
| | - Hiroyuki Iwamoto
- Japan Synchrotron Radiation Research Institute; SPring-8; Hyogo 679-5198 Japan
| | - Naoto Yagi
- Japan Synchrotron Radiation Research Institute; SPring-8; Hyogo 679-5198 Japan
| | - Jonas Bergquist
- Analytical Chemistry; Department of Chemistry - Biomedical Centre and SciLifeLab; Uppsala University; 75124 Uppsala Sweden
| | - Lars Larsson
- Department of Physiology and Pharmacology; Karolinska Institutet; SE-171 77 Stockholm Sweden
- Department of Clinical Neuroscience, Clinical Neurophysiology; Karolinska Institutet; SE-171 77 Stockholm Sweden
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76
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Muscle Quality in Aging: a Multi-Dimensional Approach to Muscle Functioning with Applications for Treatment. Sports Med 2015; 45:641-58. [DOI: 10.1007/s40279-015-0305-z] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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77
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Skeletal muscle work efficiency with age: the role of non-contractile processes. Clin Sci (Lond) 2014; 128:213-23. [PMID: 25134525 DOI: 10.1042/cs20140274] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Although skeletal muscle work efficiency probably plays a key role in limiting mobility of the elderly, the physiological mechanisms responsible for this diminished function remain incompletely understood. Thus, in the quadriceps of young (n=9) and old (n=10) subjects, we measured the cost of muscle contraction (ATP cost) with 31P-magnetic resonance spectroscopy (31P-MRS) during (i) maximal intermittent contractions to elicit a metabolic demand from both cross-bridge cycling and ion pumping and (ii) a continuous maximal contraction to predominantly tax cross-bridge cycling. The ATP cost of the intermittent contractions was significantly greater in the old (0.30±0.22 mM·min-1·N·m-1) compared with the young (0.13±0.03 mM·min-1·N·m-1, P<0.05). In contrast, at the end of the continuous contraction protocol, the ATP cost in the old (0.10±0.07 mM·min-1·N·m-1) was not different from the young (0.06±0.02 mM·min-1·N·m-1, P=0.2). In addition, the ATP cost of the intermittent contractions correlated significantly with the single leg peak power of the knee-extensors assessed during incremental dynamic exercise (r=-0.55; P<0.05). Overall, this study reveals an age-related increase in the ATP cost of contraction, probably mediated by an excessive energy demand from ion pumping, which probably contributes to both the decline in muscle efficiency and functional capacity associated with aging.
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78
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McGregor RA, Cameron-Smith D, Poppitt SD. It is not just muscle mass: a review of muscle quality, composition and metabolism during ageing as determinants of muscle function and mobility in later life. LONGEVITY & HEALTHSPAN 2014; 3:9. [PMID: 25520782 PMCID: PMC4268803 DOI: 10.1186/2046-2395-3-9] [Citation(s) in RCA: 304] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Accepted: 11/24/2014] [Indexed: 12/25/2022]
Abstract
Worldwide estimates predict 2 billion people will be aged over 65 years by 2050. A major current challenge is maintaining mobility and quality of life into old age. Impaired mobility is often a precursor of functional decline, disability and loss of independence. Sarcopenia which represents the age-related decline in muscle mass is a well-established factor associated with mobility limitations in older adults. However, there is now evidence that not only changes in muscle mass but other factors underpinning muscle quality including composition, metabolism, aerobic capacity, insulin resistance, fat infiltration, fibrosis and neural activation may also play a role in the decline in muscle function and impaired mobility associated with ageing. Importantly, changes in muscle quality may precede loss of muscle mass and therefore provide new opportunities for the assessment of muscle quality particularly in middle-aged adults who could benefit from interventions to improve muscle function. This review will discuss the accumulating evidence that in addition to muscle mass, factors underpinning muscle quality influence muscle function and mobility with age. Further development of tools to assess muscle quality in community settings is needed. Preventative diet, exercise or treatment interventions particularly in middle-aged adults at the low end of the spectrum of muscle function may help preserve mobility in later years and improve healthspan.
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Affiliation(s)
- Robin A McGregor
- School of Biological Sciences, University of Auckland, Auckland, New Zealand ; Human Nutrition Unit, University of Auckland, Auckland, New Zealand
| | | | - Sally D Poppitt
- School of Biological Sciences, University of Auckland, Auckland, New Zealand ; Human Nutrition Unit, University of Auckland, Auckland, New Zealand ; Department of Medicine, University of Auckland, Auckland, New Zealand ; Riddet Institute, Palmerston North, New Zealand
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79
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Ballak SB, Degens H, Busé-Pot T, de Haan A, Jaspers RT. Plantaris muscle weakness in old mice: relative contributions of changes in specific force, muscle mass, myofiber cross-sectional area, and number. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9726. [PMID: 25414077 PMCID: PMC4239237 DOI: 10.1007/s11357-014-9726-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Accepted: 10/29/2014] [Indexed: 06/04/2023]
Abstract
The age-related decline in muscle function contributes to the movement limitations in daily life in old age. The age-related loss in muscle force is attributable to loss of myofibers, myofiber atrophy, and a reduction in specific force. The contribution of each of these determinants to muscle weakness in old age is, however, largely unknown. The objective of this study is to determine whether a loss in myofiber number, myofiber atrophy, and a reduction in specific muscle force contribute to the age-related loss of muscle force in 25-month-old mouse. Maximal isometric force of in situ m. plantaris of C57BL/6J male adult (9 months) and old (25 months) mice was determined and related to myofiber number, myofiber size, intramuscular connective tissue content, and proportion of denervated myofibers. Isometric maximal plantaris muscle force was 13 % lower in old than adult mice (0.97 ± 0.05 N vs. 0.84 ± 0.03 N; P < 0.05). M. plantaris mass of old mice was not significantly smaller than that of adult mice. There was also no significant myofiber atrophy or myofiber loss. Specific muscle force of old mice was 25 % lower than that of adult mice (0.55 ± 0.05 vs. 0.41 ± 0.03 N·mm(-2), P < 0.01). In addition, with age, the proportion of type IIB myofibers decreased (43.6 vs. 38.4 %, respectively), while the connective tissue content increased (11.6 vs. 16.4 %, respectively). The age-related reduction in maximal isometric plantaris muscle force in 25-month-old male C57BL/6J mice is mainly attributable to a reduction in specific force, which is for 5 % explicable by an age-related increase in connective tissue, rather than myofiber atrophy and myofiber loss.
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Affiliation(s)
- Sam B. Ballak
- />School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester, UK
- />Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Van der Boechorstraat 9, 1081 BT Amsterdam, The Netherlands
| | - Hans Degens
- />School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester, UK
| | - Tinelies Busé-Pot
- />Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Van der Boechorstraat 9, 1081 BT Amsterdam, The Netherlands
| | - Arnold de Haan
- />School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester, UK
- />Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Van der Boechorstraat 9, 1081 BT Amsterdam, The Netherlands
| | - Richard T. Jaspers
- />Laboratory for Myology, MOVE Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Van der Boechorstraat 9, 1081 BT Amsterdam, The Netherlands
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80
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Kalyani RR, Corriere M, Ferrucci L. Age-related and disease-related muscle loss: the effect of diabetes, obesity, and other diseases. Lancet Diabetes Endocrinol 2014; 2:819-29. [PMID: 24731660 PMCID: PMC4156923 DOI: 10.1016/s2213-8587(14)70034-8] [Citation(s) in RCA: 665] [Impact Index Per Article: 66.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The term sarcopenia refers to the loss of muscle mass that occurs with ageing. On the basis of study results showing that muscle mass is only moderately related to functional outcomes, international working groups have proposed that loss of muscle strength or physical function should also be included in the definition. Irrespective of how sarcopenia is defined, both low muscle mass and poor muscle strength are clearly highly prevalent and important risk factors for disability and potentially mortality in individuals as they age. Many chronic diseases, in addition to ageing, could also accelerate decrease of muscle mass and strength, and this effect could be a main underlying mechanism by which chronic diseases cause physical disability. In this Review, we address both age-related and disease-related muscle loss, with a focus on diabetes and obesity but including other disease states, and potential common mechanisms and treatments. Development of treatments for age-related and disease-related muscle loss might improve active life expectancy in older people, and lead to substantial health-care savings and improved quality of life.
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Affiliation(s)
- Rita Rastogi Kalyani
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, The Johns Hopkins University, Baltimore, MD, USA
| | - Mark Corriere
- Division of Endocrinology, Diabetes, and Metabolism, Department of Medicine, The Johns Hopkins University, Baltimore, MD, USA
| | - Luigi Ferrucci
- Clinical Research Branch, National Institute on Aging, Baltimore, MD, USA.
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81
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Miller MS, Callahan DM, Toth MJ. Skeletal muscle myofilament adaptations to aging, disease, and disuse and their effects on whole muscle performance in older adult humans. Front Physiol 2014; 5:369. [PMID: 25309456 PMCID: PMC4176476 DOI: 10.3389/fphys.2014.00369] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 09/07/2014] [Indexed: 12/02/2022] Open
Abstract
Skeletal muscle contractile function declines with aging, disease, and disuse. In vivo muscle contractile function depends on a variety of factors, but force, contractile velocity and power generating capacity ultimately derive from the summed contribution of single muscle fibers. The contractile performance of these fibers are, in turn, dependent upon the isoform and function of myofilament proteins they express, with myosin protein expression and its mechanical and kinetic characteristics playing a predominant role. Alterations in myofilament protein biology, therefore, may contribute to the development of functional limitations and disability in these conditions. Recent studies suggest that these conditions are associated with altered single fiber performance due to decreased expression of myofilament proteins and/or changes in myosin-actin cross-bridge interactions. Furthermore, cellular and myofilament-level adaptations are related to diminished whole muscle and whole body performance. Notably, the effect of these various conditions on myofilament and single fiber function tends to be larger in older women compared to older men, which may partially contribute to their higher rates of disability. To maintain functionality and provide the most appropriate and effective countermeasures to aging, disease, and disuse in both sexes, a more thorough understanding is needed of the contribution of myofilament adaptations to functional disability in older men and women and their contribution to tissue level function and mobility impairment.
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Affiliation(s)
- Mark S Miller
- Department of Kinesiology, School of Public Health and Health Sciences, University of Massachusetts Amherst, MA, USA
| | - Damien M Callahan
- Department of Molecular Physiology and Biophysics, College of Medicine, University of Vermont Burlington, VT, USA
| | - Michael J Toth
- Department of Molecular Physiology and Biophysics, College of Medicine, University of Vermont Burlington, VT, USA ; Department of Medicine, College of Medicine, University of Vermont Burlington, VT, USA
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82
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Neels JG, Grimaldi PA. Physiological functions of peroxisome proliferator-activated receptor β. Physiol Rev 2014; 94:795-858. [PMID: 24987006 DOI: 10.1152/physrev.00027.2013] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The peroxisome proliferator-activated receptors, PPARα, PPARβ, and PPARγ, are a family of transcription factors activated by a diversity of molecules including fatty acids and fatty acid metabolites. PPARs regulate the transcription of a large variety of genes implicated in metabolism, inflammation, proliferation, and differentiation in different cell types. These transcriptional regulations involve both direct transactivation and interaction with other transcriptional regulatory pathways. The functions of PPARα and PPARγ have been extensively documented mainly because these isoforms are activated by molecules clinically used as hypolipidemic and antidiabetic compounds. The physiological functions of PPARβ remained for a while less investigated, but the finding that specific synthetic agonists exert beneficial actions in obese subjects uplifted the studies aimed to elucidate the roles of this PPAR isoform. Intensive work based on pharmacological and genetic approaches and on the use of both in vitro and in vivo models has considerably improved our knowledge on the physiological roles of PPARβ in various cell types. This review will summarize the accumulated evidence for the implication of PPARβ in the regulation of development, metabolism, and inflammation in several tissues, including skeletal muscle, heart, skin, and intestine. Some of these findings indicate that pharmacological activation of PPARβ could be envisioned as a therapeutic option for the correction of metabolic disorders and a variety of inflammatory conditions. However, other experimental data suggesting that activation of PPARβ could result in serious adverse effects, such as carcinogenesis and psoriasis, raise concerns about the clinical use of potent PPARβ agonists.
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Affiliation(s)
- Jaap G Neels
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
| | - Paul A Grimaldi
- Institut National de la Santé et de la Recherche Médicale U 1065, Mediterranean Center of Molecular Medicine (C3M), Team "Adaptive Responses to Immuno-metabolic Dysregulations," Nice, France; and Faculty of Medicine, University of Nice Sophia-Antipolis, Nice, France
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83
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Christie AD, Tonson A, Larsen RG, DeBlois JP, Kent JA. Human skeletal muscle metabolic economy in vivo: effects of contraction intensity, age, and mobility impairment. Am J Physiol Regul Integr Comp Physiol 2014; 307:R1124-35. [PMID: 25163917 DOI: 10.1152/ajpregu.00083.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
We tested the hypothesis that older muscle has greater metabolic economy (ME) in vivo than young, in a manner dependent, in part, on contraction intensity. Twenty young (Y; 24±1 yr, 10 women), 18 older healthy (O; 73±2, 9 women) and 9 older individuals with mild-to-moderate mobility impairment (OI; 74±1, 7 women) received stimulated twitches (2 Hz, 3 min) and performed nonfatiguing voluntary (20, 50, and 100% maximal; 12 s each) isometric dorsiflexion contractions. Torque-time integrals (TTI; Nm·s) were calculated and expressed relative to maximal fat-free muscle cross-sectional area (cm2), and torque variability during voluntary contractions was calculated as the coefficient of variation. Total ATP cost of contraction (mM) was determined from flux through the creatine kinase reaction, nonoxidative glycolysis and oxidative phosphorylation, and used to calculate ME (Nm·s·cm(-2)·mM ATP(-1)). While twitch torque relaxation was slower in O and OI compared with Y (P≤0.001), twitch TTI, ATP cost, and economy were similar across groups (P≥0.15), indicating comparable intrinsic muscle economy during electrically induced isometric contractions in vivo. During voluntary contractions, normalized TTI and total ATP cost did not differ significantly across groups (P≥0.20). However, ME was lower in OI than Y or O at 20% and 50% MVC (P≤0.02), and torque variability was greater in OI than Y or O at 20% MVC (P≤0.05). These results refute the hypothesis of greater muscle ME in old age, and provide support for lower ME in impaired older adults as a potential mechanism or consequence of age-related reductions in functional mobility.
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Affiliation(s)
- Anita D Christie
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Anne Tonson
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Ryan G Larsen
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Jacob P DeBlois
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts
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84
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Gueugneau M, Coudy-Gandilhon C, Théron L, Meunier B, Barboiron C, Combaret L, Taillandier D, Polge C, Attaix D, Picard B, Verney J, Roche F, Féasson L, Barthélémy JC, Béchet D. Skeletal muscle lipid content and oxidative activity in relation to muscle fiber type in aging and metabolic syndrome. J Gerontol A Biol Sci Med Sci 2014; 70:566-76. [PMID: 24939997 DOI: 10.1093/gerona/glu086] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 05/02/2014] [Indexed: 12/13/2022] Open
Abstract
One of the most noticeable effects of aging is the reduction in skeletal muscle mass and strength (sarcopenia). The metabolic syndrome (MS) is also prevalent in old subjects, but its relevance to skeletal muscle characteristics has poorly been investigated. Immunohistochemical studies were performed with muscle biopsies from young (22 years) and old (73 years) men with and without MS to reveal age-dependent and MS-associated modifications of fiber-type characteristics. Atrophy of type II fibers and altered fiber shape characterized muscle aging in lean healthy men. In contrast, increased cross-sectional area of the most abundant type I and type IIA fibers, and reduced cytochrome c oxidase content in all fiber types, characterized MS. Aging and particularly MS were associated with accumulation of intramyocellular lipid droplets. Although lipids mostly accumulated in type I fibers, matrix-assisted laser desorption/ionization-mass spectrometry imaging of intramyocellular lipids did not distinguish fiber types, but clearly separated young, old, and MS subjects. In conclusion, our study suggests that MS in the elderly persons is associated with alterations in skeletal muscle at a fiber-type specific level. Overall, these fiber type-specific modifications may be important both for the age-related loss of muscle mass and strength and for the increased prevalence of MS in elderly subjects.
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Affiliation(s)
- Marine Gueugneau
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Cécile Coudy-Gandilhon
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Laëtitia Théron
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. INRA, Plateforme d'Exploration du Métabolisme Composante Protéomique, Saint Genès Champanelle, France
| | - Bruno Meunier
- INRA-Vetagro Sup, UMR 1213, Unité Mixte de Recherche sur les Herbivores, Saint Genès Champanelle, France
| | - Christiane Barboiron
- INRA-Vetagro Sup, UMR 1213, Unité Mixte de Recherche sur les Herbivores, Saint Genès Champanelle, France
| | - Lydie Combaret
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Daniel Taillandier
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Cécile Polge
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Didier Attaix
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France
| | - Brigitte Picard
- INRA-Vetagro Sup, UMR 1213, Unité Mixte de Recherche sur les Herbivores, Saint Genès Champanelle, France
| | - Julien Verney
- Unité de Myologie, Centre Référent Maladies Neuromusculaires Rares Rhône-Alpes, CHU de St Etienne Laboratoire de Physiologie de l'Exercice EA4338, Université Jean Monnet de St Etienne, Université de Lyon, Saint-Etienne, France
| | - Frédéric Roche
- Service de Physiologie Clinique et de l'Exercice, CHU Nord, Faculté de Médecine Jacques Lisfranc, PRES de Lyon, Université Jean Monnet, Saint-Etienne, France
| | - Léonard Féasson
- Unité de Myologie, Centre Référent Maladies Neuromusculaires Rares Rhône-Alpes, CHU de St Etienne Laboratoire de Physiologie de l'Exercice EA4338, Université Jean Monnet de St Etienne, Université de Lyon, Saint-Etienne, France
| | - Jean-Claude Barthélémy
- Service de Physiologie Clinique et de l'Exercice, CHU Nord, Faculté de Médecine Jacques Lisfranc, PRES de Lyon, Université Jean Monnet, Saint-Etienne, France
| | - Daniel Béchet
- INRA, UMR1019, Unité de Nutrition Humaine, CRNH Auvergne, Saint Genès Champanelle, France. Clermont Université, Université d'Auvergne, Clermont-Ferrand, France.
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85
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Rudroff T, Kindred JH, Benson JM, Tracy BL, Kalliokoski KK. Greater glucose uptake heterogeneity in knee muscles of old compared to young men during isometric contractions detected by [(18)F]-FDG PET/CT. Front Physiol 2014; 5:198. [PMID: 24904432 PMCID: PMC4035600 DOI: 10.3389/fphys.2014.00198] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 05/09/2014] [Indexed: 11/16/2022] Open
Abstract
We used positron emission tomography/computed tomography (PET/CT) and [18F]-FDG to test the hypothesis that glucose uptake (GU) heterogeneity in skeletal muscles as a measure of heterogeneity in muscle activity is greater in old than young men when they perform isometric contractions. Six young (26 ± 6 years) and six old (77 ± 6 years) men performed two types of submaximal isometric contractions that required either force or position control. [18F]-FDG was injected during the task and PET/CT scans were performed immediately after the task. Within-muscle heterogeneity of knee muscles was determined by calculating the coefficient of variation (CV) of GU in PET image voxels within the muscles of interest. The average GU heterogeneity (mean ± SD) for knee extensors and flexors was greater for the old (35.3 ± 3.3%) than the young (28.6 ± 2.4%) (P = 0.006). Muscle volume of the knee extensors were greater for the young compared to the old men (1016 ± 163 vs. 598 ± 70 cm3, P = 0.004). In a multiple regression model, knee extensor muscle volume was a predictor (partial r = −0.87; P = 0.001) of GU heterogeneity for old men (R2 = 0.78; P < 0.001), and MVC force predicted GU heterogeneity for young men (partial r = −0.95, P < 0.001). The findings demonstrate that GU is more spatially variable for old than young men and especially so for old men who exhibit greater muscle atrophy.
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Affiliation(s)
- Thorsten Rudroff
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University Fort Collins, CO, USA
| | - John H Kindred
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University Fort Collins, CO, USA
| | - John-Michael Benson
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University Fort Collins, CO, USA
| | - Brian L Tracy
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University Fort Collins, CO, USA
| | - Kari K Kalliokoski
- Turku PET Centre, University of Turku and Turku University Hospital Turku, Finland
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86
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Hardman SE, Hall DE, Cabrera AJ, Hancock CR, Thomson DM. The effects of age and muscle contraction on AMPK activity and heterotrimer composition. Exp Gerontol 2014; 55:120-8. [PMID: 24747582 DOI: 10.1016/j.exger.2014.04.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 03/05/2014] [Accepted: 04/10/2014] [Indexed: 01/06/2023]
Abstract
Sarcopenia is characterized by increased skeletal muscle atrophy due in part to alterations in muscle metabolism. AMP-activated protein kinase (AMPK) is a master regulator of skeletal muscle metabolic pathways which regulate many cellular processes that are disrupted in old-age. Functional AMPK is a heterotrimer composed of α, β and γ subunits, and each subunit can be represented in the heterotrimer by one of two (α1/α2, β1/β2) or three (γ1/γ2/γ3) isoforms. Altered isoform composition affects AMPK localization and function. Previous work has shown that overall AMPK activation with endurance-type exercise is blunted in old vs. young skeletal muscle. However, details regarding the activation of the specific isoforms of AMPK, as well as the heterotrimeric composition of AMPK in old skeletal muscle, are unknown. Our purpose here, therefore, was to determine the effect of old-age on 1) the activation of the α1 and α2 catalytic subunits of AMPK in skeletal muscle by a continuous contraction bout, and 2) the heterotrimeric composition of skeletal muscle AMPK. We studied gastrocnemius (GAST) and tibialis anterior (TA) muscles from young adult (YA; 8months old) and old (O; 30months old) male Fischer344×Brown Norway F1 hybrid rats after an in situ bout of endurance-type contractions produced via electrical stimulation of the sciatic nerve (STIM). AMPKα phosphorylation and AMPKα1 and α2 activities were unaffected by age at rest. However, AMPKα phosphorylation and AMPKα2 protein content and activity were lower in O vs. YA after STIM. Conversely, AMPKα1 content was greater in O vs. YA muscle, and α1 activity increased with STIM in O but not YA muscles. AMPKγ3 overall concentration and its association with AMPKα1 and α2 were lower in O vs. YA GAST. We conclude that activation of AMPKα1 is enhanced, while activation of α2 is suppressed immediately after repeated skeletal muscle contractions in O vs. YA skeletal muscle. These changes are associated with changes in the AMPK heterotrimer composition. Given the known roles of AMPK α1, α2 and γ3, this may contribute to sarcopenia and associated muscle metabolic dysfunction.
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Affiliation(s)
- Shalene E Hardman
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Derrick E Hall
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Alyssa J Cabrera
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - Chad R Hancock
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA
| | - David M Thomson
- Department of Physiology and Developmental Biology, Brigham Young University, Provo, UT, 84602, USA.
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87
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Beharry AW, Sandesara PB, Roberts BM, Ferreira LF, Senf SM, Judge AR. HDAC1 activates FoxO and is both sufficient and required for skeletal muscle atrophy. J Cell Sci 2014; 127:1441-53. [PMID: 24463822 PMCID: PMC3970557 DOI: 10.1242/jcs.136390] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The Forkhead box O (FoxO) transcription factors are activated, and necessary for the muscle atrophy, in several pathophysiological conditions, including muscle disuse and cancer cachexia. However, the mechanisms that lead to FoxO activation are not well defined. Recent data from our laboratory and others indicate that the activity of FoxO is repressed under basal conditions via reversible lysine acetylation, which becomes compromised during catabolic conditions. Therefore, we aimed to determine how histone deacetylase (HDAC) proteins contribute to activation of FoxO and induction of the muscle atrophy program. Through the use of various pharmacological inhibitors to block HDAC activity, we demonstrate that class I HDACs are key regulators of FoxO and the muscle-atrophy program during both nutrient deprivation and skeletal muscle disuse. Furthermore, we demonstrate, through the use of wild-type and dominant-negative HDAC1 expression plasmids, that HDAC1 is sufficient to activate FoxO and induce muscle fiber atrophy in vivo and is necessary for the atrophy of muscle fibers that is associated with muscle disuse. The ability of HDAC1 to cause muscle atrophy required its deacetylase activity and was linked to the induction of several atrophy genes by HDAC1, including atrogin-1, which required deacetylation of FoxO3a. Moreover, pharmacological inhibition of class I HDACs during muscle disuse, using MS-275, significantly attenuated both disuse muscle fiber atrophy and contractile dysfunction. Together, these data solidify the importance of class I HDACs in the muscle atrophy program and indicate that class I HDAC inhibitors are feasible countermeasures to impede muscle atrophy and weakness.
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Affiliation(s)
- Adam W. Beharry
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610-0154, USA
| | - Pooja B. Sandesara
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610-0154, USA
| | - Brandon M. Roberts
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610-0154, USA
| | - Leonardo F. Ferreira
- Department of Applied Physiology and Kinesiology, University of Florida, Gainesville, FL 32610-0154, USA
| | - Sarah M. Senf
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610-0154, USA
| | - Andrew R. Judge
- Department of Physical Therapy, University of Florida, Gainesville, FL 32610-0154, USA
- Author for correspondence ()
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88
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Ballak SB, Degens H, de Haan A, Jaspers RT. Aging related changes in determinants of muscle force generating capacity: a comparison of muscle aging in men and male rodents. Ageing Res Rev 2014; 14:43-55. [PMID: 24495393 DOI: 10.1016/j.arr.2014.01.005] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 01/20/2014] [Accepted: 01/24/2014] [Indexed: 12/25/2022]
Abstract
Human aging is associated with a progressive decline in skeletal muscle mass and force generating capacity, however the exact mechanisms underlying these changes are not fully understood. Rodents models have often been used to enhance our understanding of mechanisms of age-related changes in human skeletal muscle. However, to what extent age-related alterations in determinants of muscle force generating capacity observed in rodents resemble those in humans has not been considered thoroughly. This review compares the effect of aging on muscle force generating determinants (muscle mass, fiber size, fiber number, fiber type distribution and muscle specific tension), in men and male rodents at similar relative age. It appears that muscle aging in male F344*BN rat resembles that in men most; 32-35-month-old rats exhibit similar signs of muscle weakness to those of 70-80-yr-old men, and the decline in 36-38-month-old rats is similar to that in men aged over 80 yrs. For male C57BL/6 mice, age-related decline in muscle force generating capacity seems to occur only at higher relative age than in men. We conclude that the effects on determinants of muscle force differ between species as well as within species, but qualitatively show the same pattern as that observed in men.
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Affiliation(s)
- Sam B Ballak
- School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom; Laboratory for Myology, Move Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam 1081 BT, The Netherlands.
| | - Hans Degens
- School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom
| | - Arnold de Haan
- School of Healthcare Science, Cognitive Motor Function Research Group, Manchester Metropolitan University, Manchester M1 5GD, United Kingdom; Laboratory for Myology, Move Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam 1081 BT, The Netherlands
| | - Richard T Jaspers
- Laboratory for Myology, Move Research Institute Amsterdam, Faculty of Human Movement Sciences, VU University Amsterdam, Amsterdam 1081 BT, The Netherlands
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89
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Demontis F, Piccirillo R, Goldberg AL, Perrimon N. Mechanisms of skeletal muscle aging: insights from Drosophila and mammalian models. Dis Model Mech 2013; 6:1339-52. [PMID: 24092876 PMCID: PMC3820258 DOI: 10.1242/dmm.012559] [Citation(s) in RCA: 162] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A characteristic feature of aged humans and other mammals is the debilitating, progressive loss of skeletal muscle function and mass that is known as sarcopenia. Age-related muscle dysfunction occurs to an even greater extent during the relatively short lifespan of the fruit fly Drosophila melanogaster. Studies in model organisms indicate that sarcopenia is driven by a combination of muscle tissue extrinsic and intrinsic factors, and that it fundamentally differs from the rapid atrophy of muscles observed following disuse and fasting. Extrinsic changes in innervation, stem cell function and endocrine regulation of muscle homeostasis contribute to muscle aging. In addition, organelle dysfunction and compromised protein homeostasis are among the primary intrinsic causes. Some of these age-related changes can in turn contribute to the induction of compensatory stress responses that have a protective role during muscle aging. In this Review, we outline how studies in Drosophila and mammalian model organisms can each provide distinct advantages to facilitate the understanding of this complex multifactorial condition and how they can be used to identify suitable therapies.
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Affiliation(s)
- Fabio Demontis
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
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90
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Larkin LM, Hanes MC, Kayupov E, Claflin DR, Faulkner JA, Brooks SV. Weakness of whole muscles in mice deficient in Cu, Zn superoxide dismutase is not explained by defects at the level of the contractile apparatus. AGE (DORDRECHT, NETHERLANDS) 2013; 35:1173-1181. [PMID: 22696118 PMCID: PMC3705120 DOI: 10.1007/s11357-012-9441-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 05/21/2012] [Indexed: 06/01/2023]
Abstract
Mice deficient in Cu,Zn superoxide dismutase (Sod1 (-/-) mice) demonstrate elevated oxidative stress associated with rapid age-related declines in muscle mass and force. The decline in mass for muscles of Sod1 (-/-) mice is explained by a loss of muscle fibers, but the mechanism underlying the weakness is not clear. We hypothesized that the reduced maximum isometric force (F o) normalized by cross-sectional area (specific F o) for whole muscles of Sod1 (-/-) compared with wild-type (WT) mice is due to decreased specific F o of individual fibers. Force generation was measured for permeabilized fibers from muscles of Sod1 (-/-) and WT mice at 8 and 20 months of age. WT mice were also studied at 28 months to determine whether any deficits observed for fibers from Sod1 (-/-) mice were similar to those observed in old WT mice. No effects of genotype were observed for F o or specific F o at either 8 or 20 months, and no age-associated decrease in specific F o was observed for fibers from Sod1 (-/-) mice, whereas specific F o for fibers of WT mice decreased by 20 % by 28 months. Oxidative stress has also been associated with decreased maximum velocity of shortening (V max), and we found a 10 % lower V max for fibers from Sod1 (-/-) compared with WT mice at 20 months. We conclude that the low specific F o of muscles of Sod1 (-/-) mice is not explained by damage to contractile proteins. Moreover, the properties of fibers of Sod1 (-/-) mice do not recapitulate those observed with aging in WT animals.
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Affiliation(s)
- Lisa M. Larkin
- />Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109-2200 USA
- />Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
| | - Michael C. Hanes
- />Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109-2200 USA
| | - Erdan Kayupov
- />Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
| | - Dennis R. Claflin
- />Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
- />Surgery, Section of Plastic Surgery, University of Michigan, Ann Arbor, MI 48109 USA
| | - John A. Faulkner
- />Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109-2200 USA
- />Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
| | - Susan V. Brooks
- />Departments of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI 48109-2200 USA
- />Biomedical Engineering, University of Michigan, Ann Arbor, MI 48109 USA
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91
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Miller MS, Bedrin NG, Callahan DM, Previs MJ, Jennings ME, Ades PA, Maughan DW, Palmer BM, Toth MJ. Age-related slowing of myosin actin cross-bridge kinetics is sex specific and predicts decrements in whole skeletal muscle performance in humans. J Appl Physiol (1985) 2013; 115:1004-14. [PMID: 23887900 DOI: 10.1152/japplphysiol.00563.2013] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesize that age-related skeletal muscle dysfunction and physical disability may be partially explained by alterations in the function of the myosin molecule. To test this hypothesis, skeletal muscle function at the whole muscle, single fiber, and molecular levels was measured in young (21-35 yr) and older (65-75 yr) male and female volunteers with similar physical activity levels. After adjusting for muscle size, older adults had similar knee extensor isometric torque values compared with young, but had lower isokinetic power, most notably in women. At the single-fiber and molecular levels, aging was associated with increased isometric tension, slowed myosin actin cross-bridge kinetics (longer myosin attachment times and reduced rates of myosin force production), greater myofilament lattice stiffness, and reduced phosphorylation of the fast myosin regulatory light chain; however, the age effect was driven primarily by women (i.e., age-by-sex interaction effects). In myosin heavy chain IIA fibers, single-fiber isometric tension and molecular level mechanical and kinetic indexes were correlated with whole muscle isokinetic power output. Collectively, considering that contractile dysfunction scales up through various anatomical levels, our results suggest a potential sex-specific molecular mechanism, reduced cross-bridge kinetics, contributes to the reduced physical capacity with aging in women. Thus these results support our hypothesis that age-related alterations in the myosin molecule contribute to skeletal muscle dysfunction and physical disability and indicate that this effect is stronger in women.
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Affiliation(s)
- Mark S Miller
- Department of Molecular Physiology and Biophysics, University of Vermont, College of Medicine, Burlington, Vermont
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92
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Relationship between muscle mass and muscle strength, and the impact of comorbidities: a population-based, cross-sectional study of older adults in the United States. BMC Geriatr 2013; 13:74. [PMID: 23865675 PMCID: PMC3765109 DOI: 10.1186/1471-2318-13-74] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 06/24/2013] [Indexed: 12/25/2022] Open
Abstract
Background Loss of muscle mass and muscle strength are natural consequences of the aging process, accompanied by an increased prevalence of chronic health conditions. Research suggests that in the elderly, the presence of comorbidities may impact the muscle mass/strength relationship. The objectives of this study were to characterize the muscle mass/strength relationship in older adults in the USA and to examine the impact of a variety of comorbidities on this relationship. Methods Data were obtained from the National Health and Nutrition Examination Survey 1999–2002 databases. Subjects aged 50 years and older were included in the present study. Muscle mass was assessed by height-adjusted appendicular skeleton muscle mass (aASM) in kg/m2, as measured by dual-energy x-ray absorptiometry. Muscle strength was assessed via isokinetic quadriceps strength (IQS) in newton as measured by a dynamometer. The relationship between aASM and IQS was assessed adjusting for age and gender. The effects of a variety of comorbidities on IQS and/or on the relationship between IQS and aASM were assessed using multiple regression models. Results This study included 2,647 individuals, with a mean age of 62.6 years and 52.9% of whom were female. The mean (SE) aASM (kg/m2) was 7.3 (0.04), and the mean (SE) IQS (newton) was 365.0 (3.00). After adjusting for age and gender, the correlation coefficient between aASM and IQS was 0.365 (P < 0.001). Diabetes, coronary heart disease/congestive heart failure (CHD/CHF), and vision problems were significant predictors of lower muscle strength (P < 0.05) in the multiple regression models that adjusted for age, gender, and aASM, and obesity significantly modified the relationship between aASM and IQS (P < 0.05). Conclusions Among individuals aged 50 and older in the US, muscle mass and muscle strength are positively correlated, independent of the associations of age and gender with muscle mass and strength. A variety of comorbid medical conditions serve as independent predictors of lower muscle strength (e.g., diabetes, CHD/CHF, vision problems) and/or modify the relationship between muscle mass and muscle strength (e.g., obesity).
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93
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Kent-Braun JA, Callahan DM, Fay JL, Foulis SA, Buonaccorsi JP. Muscle weakness, fatigue, and torque variability: effects of age and mobility status. Muscle Nerve 2013; 49:209-17. [PMID: 23674266 DOI: 10.1002/mus.23903] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/07/2013] [Indexed: 11/07/2022]
Abstract
INTRODUCTION Whereas deficits in muscle function, particularly power production, develop in old age and are risk factors for mobility impairment, a complete understanding of muscle fatigue during dynamic contractions is lacking. We tested hypotheses related to torque-producing capacity, fatigue resistance, and variability of torque production during repeated maximal contractions in healthy older, mobility-impaired older, and young women. METHODS Knee extensor fatigue (decline in torque) was measured during 4 min of dynamic contractions. Torque variability was characterized using a novel 4-component logistic regression model. RESULTS Young women produced more torque at baseline and during the protocol than older women (P < 0.001). Although fatigue did not differ between groups (P = 0.53), torque variability differed by group (P = 0.022) and was greater in older impaired compared with young women (P = 0.010). CONCLUSIONS These results suggest that increased torque variability may combine with baseline muscle weakness to limit function, particularly in older adults with mobility impairments.
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Affiliation(s)
- Jane A Kent-Braun
- Department of Kinesiology, University of Massachusetts, 108 Totman Building, 30 Eastman Lane, Amherst, Massachusetts, 01003, USA
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94
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McPhee JS, Hogrel JY, Maier AB, Seppet E, Seynnes OR, Sipilä S, Bottinelli R, Barnouin Y, Bijlsma AY, Gapeyeva H, Maden-Wilkinson TM, Meskers CG, Pääsuke M, Sillanpää E, Stenroth L, Butler-Browne G, Narici MV, Jones DA. Physiological and functional evaluation of healthy young and older men and women: design of the European MyoAge study. Biogerontology 2013; 14:325-37. [PMID: 23722256 DOI: 10.1007/s10522-013-9434-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 05/21/2013] [Indexed: 12/25/2022]
Abstract
Within the European multi-centre MyoAge project, one workpackage was designed to investigate the contribution of age-related changes to muscle mass, contractile characteristics and neural control in relation to reductions in mobility in older age. The methodology has been described here. Test centres were located in Manchester, UK; Paris, France; Leiden, The Netherlands; Tartu, Estonia and Jyväskylä, Finland. In total, 182 young (18-30 years old, 52.2 % female) and 322 older adults (69-81 years old, 50 % female) have been examined. The participants were independent living, socially active and free from disease that impaired mobility levels. The older participants were selected based on physical activity levels, such that half exceeded current recommended physical activity levels and the other half had lower physical activity levels than is recommended to maintain health. Measurements consisted of blood pressure; anthropometry and body composition (dual-energy X-ray absorptiometry and magnetic resonance imaging); lung function; standing balance and cognitive function (CANTAB). Mobility was assessed using the Timed Up and Go, a 6 min walk, activity questionnaires and accelerometers to monitor habitual daily activities. Muscle strength, power, fatigue and neural activation were assessed using a combination of voluntary and electrically stimulated contractions. Fasting blood samples and skeletal muscle biopsies were collected for detailed examination of cell and molecular differences between young and older individuals. The results from this study will provide a detailed insight into "normal, healthy" ageing, linking whole-body function to the structure and function of the neuromuscular system and the molecular characteristics of skeletal muscle.
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Affiliation(s)
- Jamie S McPhee
- School of Healthcare Science, John Dalton Building, Manchester Metropolitan University, Manchester, M1 5GD, UK.
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95
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Ramamurthy B, Larsson L. Detection of an aging-related increase in advanced glycation end products in fast- and slow-twitch skeletal muscles in the rat. Biogerontology 2013; 14:293-301. [PMID: 23681254 DOI: 10.1007/s10522-013-9430-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2013] [Accepted: 04/29/2013] [Indexed: 01/23/2023]
Abstract
Glycation, a non-enzymatic addition of reducing sugars to ε-amino groups of proteins, is a post-translational modification that results in the formation of irreversible advanced glycation end products (AGEs). Ageing related decline in myofibrillar protein function is effected by a number of structural and functional modifications including glycation. Functional properties of skeletal muscles, such as maximum velocity of unloaded shortening, are known to be profoundly affected by ageing at the motor unit, cellular and tissue levels. However, the contribution of protein modifications to a decline in muscle function is not well understood. In this study we measured AGEs of intracellular and sarcolemmal proteins, using an anti-AGE antibody in soleus (SOL) and extensor digiotorum longus (EDL) muscles of male and female rats of five different age groups. Using a fluorescent secondary antibody to visualize AGEs in the confocal microscope, we found that myosin is glycated in both fiber types in all age groups; an ageing related increase in AGEs was observed in both intracellular and sarcolemmal regions in all age groups, with the exception of sarcolemma of SOL (unchanged) and EDL (reduced) in female rats; the greatest concentration of AGEs was found intracellularly in the SOL of the oldest age group (27-30) of females. While an ageing related decline in motor properties can be partially attributed to the observed increase in myofibrillar protein glycation, our results also indicate that intracellular and the less well studied sarcolemmal protein modification likely contribute to an aging-related decline in muscle function. Further studies are required to establish a link between the observed ageing related increase in glycation and muscle function at the motor unit, cellular and tissue levels.
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Affiliation(s)
- B Ramamurthy
- Department of Biobehavioral Health, The Pennsylvania State University, University Park, PA, USA
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96
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Mackrell JG, Arias EB, Cartee GD. Fiber type-specific differences in glucose uptake by single fibers from skeletal muscles of 9- and 25-month-old rats. J Gerontol A Biol Sci Med Sci 2012; 67:1286-94. [PMID: 23042591 DOI: 10.1093/gerona/gls194] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The primary purpose of this study was to assess the feasibility of applying a novel approach to measure myosin heavy chain (MHC) isoform expression, glucose uptake, fiber volume, and protein abundance in single muscle fibers of adult (9 months) and old (25 months) rats. Epitrochlearis muscle fibers were successfully isolated and analyzed for MHC isoform expression, glucose uptake, fiber volume, and protein (COXIV, APPL1, IκB-β) abundance. Insulin-stimulated glucose uptake by single fibers did not differ between age groups, but there was a significant difference between fiber types (IIA > IIX > IIB/X ≈ IIB). There were also significant main effects of fiber type on APPL1 (IIX > IIB) and COXIV (IIA > IIX > IIB/X ≈ IIB) abundance, and IIB fibers were significantly larger than IIA fibers. This study established the feasibility of a new approach for assessing age-related differences in muscle at the single-fiber level and demonstrated the magnitude and rank order for fiber-type differences in insulin-stimulated glucose uptake of 9-month-old and 25-month-old rats.
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Affiliation(s)
- James G Mackrell
- University of Michigan, School of Kinesiology, Room 4745F 401 Washtenaw Avenue, Ann Arbor, MI 48109-2214, USA
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97
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Alamdari N, Toraldo G, Aversa Z, Smith I, Castillero E, Renaud G, Qaisar R, Larsson L, Jasuja R, Hasselgren PO. Loss of muscle strength during sepsis is in part regulated by glucocorticoids and is associated with reduced muscle fiber stiffness. Am J Physiol Regul Integr Comp Physiol 2012; 303:R1090-9. [PMID: 23019215 DOI: 10.1152/ajpregu.00636.2011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Sepsis is associated with impaired muscle function but the role of glucocorticoids in sepsis-induced muscle weakness is not known. We tested the role of glucocorticoids in sepsis-induced muscle weakness by treating septic rats with the glucocorticoid receptor antagonist RU38486. In addition, normal rats were treated with dexamethasone to further examine the role of glucocorticoids in the regulation of muscle strength. Sepsis was induced in rats by cecal ligation and puncture, and muscle force generation (peak twitch and tetanic tension) was determined in lower extremity muscles. In other experiments, absolute and specific force as well as stiffness (reflecting the function of actomyosin cross bridges) were determined in isolated skinned muscle fibers from control and septic rats. Sepsis and treatment with dexamethasone resulted in reduced maximal twitch and tetanic force in intact isolated extensor digitorum longus muscles. The absolute and specific maximal force in isolated muscle fibers was reduced during sepsis together with decreased fiber stiffness. These effects of sepsis were blunted (but not abolished) by RU38486. The results suggest that muscle weakness during sepsis is at least in part regulated by glucocorticoids and reflects loss of contractility at the cellular (individual muscle fiber) level. In addition, the results suggest that reduced function of the cross bridges between actin and myosin (documented as reduced muscle fiber stiffness) may be involved in sepsis-induced muscle weakness. An increased understanding of mechanisms involved in loss of muscle strength will be important for the development of new treatment strategies in patients with this debilitating consequence of sepsis.
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Affiliation(s)
- Nima Alamdari
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
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98
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Choi SJ, Shively CA, Register TC, Feng X, Stehle J, High K, Ip E, Kritchevsky SB, Nicklas B, Delbono O. Force-generation capacity of single vastus lateralis muscle fibers and physical function decline with age in African green vervet monkeys. J Gerontol A Biol Sci Med Sci 2012; 68:258-67. [PMID: 22923428 DOI: 10.1093/gerona/gls143] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Previous studies on the contractile properties of human myofibrils reported increase, decrease, or no change with aging, perhaps due to the differences in physical activity, diet, and other factors. This study examined physical performance and contractile characteristics of myofibrils of vastus lateralis (VL) muscle in young adult and old African green vervet monkeys. Animals were offered the same diet and lived in the same enclosures during development, so we were able to examine skeletal muscle function in vivo and in vitro with fewer potential confounding factors than are typical in human research studies. Fiber atrophy alone did not account for the age-related differences in specific force and maximal power output. Regression modeling used to identify factors contributing to lower fiber force revealed that age is the strongest predictor. Our results support a detrimental effect of aging on the intrinsic force and power generation of myofilament lattice and physical performance in vervet monkeys.
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Affiliation(s)
- Seung Jun Choi
- Department of Internal Medicine, Gerontology, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
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99
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Cutroneo G, Piancino MG, Ramieri G, Bracco P, Vita G, Isola G, Vermiglio G, Favaloro A, Anastasi G, Trimarchi F. Expression of muscle-specific integrins in masseter muscle fibers during malocclusion disease. Int J Mol Med 2012; 30:235-42. [PMID: 22552408 DOI: 10.3892/ijmm.2012.986] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Accepted: 03/05/2012] [Indexed: 02/07/2023] Open
Abstract
Integrins are heterodimeric cell surface membrane proteins linking the extracellular matrix to actin. α7B integrin is detected in proliferating and adult myofibers, whereas α7A plays a role in regenerating muscle fibers with a minor function in mature muscle fibers. The expression levels of β1A appear to be very low, whereas β1D appears to be the predominant integrin form in mature muscle. Considering the important features of masseter muscle we have studied integrin expression in masseter muscle specimens of surgical patients with posterior right crossbite and comparing them to left side masseter muscle specimens. Our results showed that the expression of integrins was significantly lower in the crossbite side muscle. Furthermore, the most important finding is that β1A is clearly detectable in adult masseter muscle. This behavior could be due to the particular composition of masseter, since it contains hybrid fibers showing the capacity to modify the contractile properties to optimize the energy efficiency or the action of the muscle during contraction. Moreover, masseter is characterized by a high turnover of muscle fibers producing a regeneration process. This may indicate a longer time to heal, justifying the loss of β1D and the consequential increase of β1A. Thus, our data provide the first suggestion that integrins in masseter muscle play a key role regulating the functional activity of muscle and allowing the optimization of contractile forces.
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Affiliation(s)
- Giuseppina Cutroneo
- Department of Biomorphology and Biotechnologies, Messina University, I-98125 Messina, Italy
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100
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Clark BC, Manini TM. What is dynapenia? Nutrition 2012; 28:495-503. [PMID: 22469110 DOI: 10.1016/j.nut.2011.12.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Accepted: 12/06/2011] [Indexed: 12/25/2022]
Abstract
Dynapenia (pronounced dahy-nuh-pē-nē-a, Greek translation for poverty of strength, power, or force) is the age-associated loss of muscle strength that is not caused by neurologic or muscular diseases. Dynapenia predisposes older adults to an increased risk for functional limitations and mortality. For the past several decades, the literature has largely focused on muscle size as the primary cause of dynapenia; however, recent findings have clearly demonstrated that muscle size plays a relatively minor role. Conversely, subclinical deficits in the structure and function of the nervous system and/or impairments in the intrinsic force-generating properties of skeletal muscle are potential antecedents to dynapenia. This review highlights in the contributors to dynapenia and the etiology and risk factors that predispose individuals to dynapenia. In addition, we address the role of nutrition in the muscular and neurologic systems for the preservation of muscle strength throughout the life span.
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Affiliation(s)
- Brian C Clark
- Ohio Musculoskeletal and Neurological Institute (OMNI) and Department of Biomedical Sciences, Ohio University, Athens, Ohio, USA.
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