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Arieta LR, Smith ZH, Paluch AE, Kent JA. Effects of older age on contraction-induced intramyocellular acidosis and inorganic phosphate accumulation in vivo: A systematic review and meta-analysis. PLoS One 2024; 19:e0308336. [PMID: 39321147 PMCID: PMC11424002 DOI: 10.1371/journal.pone.0308336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2024] [Accepted: 07/22/2024] [Indexed: 09/27/2024] Open
Abstract
Although it is clear that the bioenergetic basis of skeletal muscle fatigue (transient decrease in peak torque or power in response to contraction) involves intramyocellular acidosis (decreased pH) and accumulation of inorganic phosphate (Pi) in response to the increased energy demand of contractions, the effects of old age on the build-up of these metabolites has not been evaluated systematically. The purpose of this study was to compare pH and [Pi] in young (18-45 yr) and older (55+ yr) human skeletal muscle in vivo at the end of standardized contraction protocols. Full study details were prospectively registered on PROSPERO (CRD42022348972). PubMed, Web of Science, and SPORTDiscus databases were systematically searched and returned 12 articles that fit the inclusion criteria for the meta-analysis. Participant characteristics, contraction mode (isometric, dynamic), and final pH and [Pi] were extracted. A random-effects model was used to calculate the mean difference (MD) and 95% confidence interval (CI) for pH and [Pi] across age groups. A subgroup analysis for contraction mode was also performed. Young muscle acidified more than older muscle (MD = -0.12 pH; 95%CI = -0.18,-0.06; p<0.01). There was no overall difference by age in final [Pi] (MD = 2.14 mM; 95%CI = -0.29,4.57; p = 0.08), although sensitivity analysis revealed that removing one study resulted in greater [Pi] in young than older muscle (MD = 3.24 mM; 95%CI = 1.72,4.76; p<0.01). Contraction mode moderated these effects (p = 0.02) such that young muscle acidified (MD = -0.19 pH; 95%CI = -0.27,-0.11; p<0.01) and accumulated Pi (MD = 4.69 mM; 95%CI = 2.79,6.59; p<0.01) more than older muscle during isometric, but not dynamic, contractions. The smaller energetic perturbation in older muscle indicated by these analyses is consistent with its relatively greater use of oxidative energy production. During dynamic contractions, elimination of this greater reliance on oxidative energy production and consequently lower metabolite accumulations in older muscle may be important for understanding task-specific, age-related differences in fatigue.
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Affiliation(s)
- Luke R Arieta
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Zoe H Smith
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
| | - Amanda E Paluch
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
- Institute for Applied Life Sciences, University of Massachusetts, Amherst, MA, United States of America
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts, Amherst, MA, United States of America
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Lanza IR, Sundberg CW, Kent JA. Reduced oxidative capacity of skeletal muscle IS NOT an inevitable consequence of adult ageing. J Physiol 2024. [PMID: 38970775 DOI: 10.1113/jp285042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 03/04/2024] [Indexed: 07/08/2024] Open
Affiliation(s)
| | | | - Jane A Kent
- University of Massachusetts Amherst, Amherst, USA
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Bartlett MF, Fitzgerald LF, Nagarajan R, Kent JA. Measurements of in vivo skeletal muscle oxidative capacity are lower following sustained isometric compared with dynamic contractions. Appl Physiol Nutr Metab 2024; 49:250-264. [PMID: 37906958 DOI: 10.1139/apnm-2023-0315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Human skeletal muscle oxidative capacity can be quantified non-invasively using 31-phosphorus magnetic resonance spectroscopy (31P-MRS) to measure the rate constant of phosphocreatine (PCr) recovery (kPCr) following contractions. In the quadricep muscles, several studies have quantified kPCr following 24-30 s of sustained maximal voluntary isometric contraction (MVIC). This approach has the advantage of simplicity but is potentially problematic because sustained MVICs inhibit perfusion, which may limit muscle oxygen availability or increase the intracellular metabolic perturbation, and thus affect kPCr. Alternatively, dynamic contractions allow reperfusion between contractions, which may avoid limitations in oxygen delivery. To determine whether dynamic contraction protocols elicit greater kPCr than sustained MVIC protocols, we used a cross-sectional design to compare quadriceps kPCr in 22 young and 11 older healthy adults following 24 s of maximal voluntary: (1) sustained MVIC and (2) dynamic (MVDC; 120°·s-1, 1 every 2 s) contractions. Muscle kPCr was ∼20% lower following the MVIC protocol compared with the MVDC protocol (p ≤ 0.001), though this was less evident in older adults (p = 0.073). Changes in skeletal muscle pH (p ≤ 0.001) and PME accumulation (p ≤ 0.001) were greater following the sustained MVIC protocol, and pH (p ≤ 0.001) and PME (p ≤ 0.001) recovery were slower. These results demonstrate that (i) a brief, sustained MVIC yields a lower value for skeletal muscle oxidative capacity than an MVDC protocol of similar duration and (ii) this difference may not be consistent across populations (e.g., young vs. old). Thus, the potential effect of contraction protocol on comparisons of kPCr in different study groups requires careful consideration in the future.
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Affiliation(s)
- Miles F Bartlett
- Department of KinesiologyMuscle Physiology Laboratory, University of Massachusetts Amherst, MA 01003, USA
| | - Liam F Fitzgerald
- Department of KinesiologyMuscle Physiology Laboratory, University of Massachusetts Amherst, MA 01003, USA
| | - Rajakumar Nagarajan
- Human Magnetic Resonance Center, Institute for Applied Life Sciences (IALS), University of Massachusetts Amherst, MA 01003, USA
| | - Jane A Kent
- Department of KinesiologyMuscle Physiology Laboratory, University of Massachusetts Amherst, MA 01003, USA
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Hayden CMT, Nagarajan R, Smith ZH, Gilmore S, Kent JA. Postcontraction [acetylcarnitine] reflects interindividual variation in skeletal muscle ATP production patterns in vivo. Am J Physiol Regul Integr Comp Physiol 2024; 326:R66-R78. [PMID: 37955131 DOI: 10.1152/ajpregu.00027.2023] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/14/2023]
Abstract
In addition to its role in substrate selection (carbohydrate vs. fat) for oxidative metabolism in muscle, acetylcarnitine production may be an important modulator of the energetic pathway by which ATP is produced. A combination of noninvasive magnetic resonance spectroscopy measures of cytosolic acetylcarnitine and ATP production pathways was used to investigate the link between [acetylcarnitine] and energy production in vivo. Intracellular metabolites were measured in the vastus lateralis muscle of eight males (mean: 28.4 yr, range: 25-35) during 8 min of incremental, dynamic contractions (0.5 Hz, 2-min stages at 6%, 9%, 12%, and 15% maximal torque) that increased [acetylcarnitine] approximately fivefold from resting levels. ATP production via oxidative phosphorylation, glycolysis, and the creatine kinase reaction was calculated based on phosphorus metabolites and pH. Spearman rank correlations indicated that postcontraction [acetylcarnitine] was positively associated with both absolute (mM) and relative (% total ATP) glycolytic ATP production (rs = 0.95, P = 0.001; rs = 0.93, P = 0.002), and negatively associated with relative (rs = -0.81, P = 0.02) but not absolute (rs = -0.14, P = 0.75) oxidative ATP production. Thus, acetylcarnitine accumulated more when there was a greater reliance on "nonoxidative" glycolysis and a relatively lower contribution from oxidative phosphorylation, reflecting the fate of pyruvate in working skeletal muscle. Furthermore, these data indicate striking interindividual variation in responses to the energy demand of submaximal contractions. Overall, the results of this preliminary study provide novel evidence of the coupling in vivo between ATP production pathways and the carnitine system.NEW & NOTEWORTHY Production of acetylcarnitine from acetyl-CoA and free carnitine may be important for energy pathway regulation in contracting skeletal muscle. Noninvasive magnetic resonance spectroscopy was used to investigate the link between acetylcarnitine and energy production in the vastus lateralis muscle during dynamic contractions (n = 8 individuals). A positive correlation between acetylcarnitine accumulation and "nonoxidative" glycolysis and an inverse relationship with oxidative phosphorylation, provides novel evidence of the coupling between ATP production and the carnitine system in vivo.
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Affiliation(s)
- Christopher M T Hayden
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
| | - Rajakumar Nagarajan
- Human Magnetic Resonance Center, Institute for Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts, United States
| | - Zoe H Smith
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
| | - Samantha Gilmore
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
| | - Jane A Kent
- Muscle Physiology Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts, United States
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Fitzgerald LF, Bartlett MF, Kent JA. Muscle fatigue, bioenergetic responses and metabolic economy during load- and velocity-based maximal dynamic contractions in young and older adults. Physiol Rep 2023; 11:e15876. [PMID: 37996974 PMCID: PMC10667588 DOI: 10.14814/phy2.15876] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 11/07/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023] Open
Abstract
We evaluated whether task-dependent, age-related differences in muscle fatigue (contraction-induced decline in normalized power) develop from differences in bioenergetics or metabolic economy (ME; mass-normalized work/mM ATP). We used magnetic resonance spectroscopy to quantify intracellular metabolites in vastus lateralis muscle of 10 young and 10 older adults during two maximal-effort, 4-min isotonic (20% maximal torque) and isokinetic (120°s-1 ) contraction protocols. Fatigue, inorganic phosphate (Pi), and pH (p ≥ 0.213) differed by age during isotonic contractions. However, older had less fatigue (p ≤ 0.011) and metabolic perturbation (lower [Pi], greater pH; p ≤ 0.031) than young during isokinetic contractions. ME was lower in older than young during isotonic contractions (p ≤ 0.003), but not associated with fatigue in either protocol or group. Rather, fatigue during both tasks was linearly related to changes in [H+ ], in both groups. The slope of fatigue versus [H+ ] was 50% lower in older than young during isokinetic contractions (p ≤ 0.023), consistent with less fatigue in older during this protocol. Overall, regardless of age or task type, acidosis, but not ME, was the primary mechanism for fatigue in vivo. The source of the age-related differences in contraction-induced acidosis in vivo remains to be determined, as does the apparent task-dependent difference in the sensitivity of muscle to [H+ ].
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Affiliation(s)
- Liam F. Fitzgerald
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
| | - Miles F. Bartlett
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
| | - Jane A. Kent
- Muscle Physiology Laboratory, Department of KinesiologyUniversity of MassachusettsAmherstMassachusettsUSA
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Boyer KA, Hayes KL, Umberger BR, Adamczyk PG, Bean JF, Brach JS, Clark BC, Clark DJ, Ferrucci L, Finley J, Franz JR, Golightly YM, Hortobágyi T, Hunter S, Narici M, Nicklas B, Roberts T, Sawicki G, Simonsick E, Kent JA. Age-related changes in gait biomechanics and their impact on the metabolic cost of walking: Report from a National Institute on Aging workshop. Exp Gerontol 2023; 173:112102. [PMID: 36693530 PMCID: PMC10008437 DOI: 10.1016/j.exger.2023.112102] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 01/09/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Changes in old age that contribute to the complex issue of an increased metabolic cost of walking (mass-specific energy cost per unit distance traveled) in older adults appear to center at least in part on changes in gait biomechanics. However, age-related changes in energy metabolism, neuromuscular function and connective tissue properties also likely contribute to this problem, of which the consequences are poor mobility and increased risk of inactivity-related disease and disability. The U.S. National Institute on Aging convened a workshop in September 2021 with an interdisciplinary group of scientists to address the gaps in research related to the mechanisms and consequences of changes in mobility in old age. The goal of the workshop was to identify promising ways to move the field forward toward improving gait performance, decreasing energy cost, and enhancing mobility for older adults. This report summarizes the workshop and brings multidisciplinary insight into the known and potential causes and consequences of age-related changes in gait biomechanics. We highlight how gait mechanics and energy cost change with aging, the potential neuromuscular mechanisms and role of connective tissue in these changes, and cutting-edge interventions and technologies that may be used to measure and improve gait and mobility in older adults. Key gaps in the literature that warrant targeted research in the future are identified and discussed.
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Affiliation(s)
- Katherine A Boyer
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA; Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Medical School, Worcester, MA, USA.
| | - Kate L Hayes
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA
| | | | | | - Jonathan F Bean
- New England GRECC, VA Boston Healthcare System, Boston, MA, USA; Department of PM&R, Harvard Medical School, Boston, MA, USA; Spaulding Rehabilitation Hospital, Boston, MA, USA
| | - Jennifer S Brach
- Department of Physical Therapy, University of Pittsburgh, Pittsburgh, PA, USA
| | - Brian C Clark
- Ohio Musculoskeletal and Neurological Institute and the Department of Biomedical Sciences, Ohio University, Athens, OH, USA
| | - David J Clark
- Brain Rehabilitation Research Center, Malcom Randall VA Medical Center, Gainesville, FL, USA; Department of Physiology and Aging, University of Florida, Gainesville, FL, USA
| | - Luigi Ferrucci
- Intramural Research Program of the National Institute on Aging, NIH, Baltimore, MD, USA
| | - James Finley
- Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA, USA
| | - Jason R Franz
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill and North Carolina State University, Chapel Hill, NC, USA
| | - Yvonne M Golightly
- College of Allied Health Professions, University of Nebraska Medical Center, Omaha, NE, USA; Thurston Arthritis Research Center, Division of Rheumatology, Allergy, and Immunology, Department of Medicine, University of North Carolina, Chapel Hill, NC, USA
| | - Tibor Hortobágyi
- Hungarian University of Sports Science, Department of Kinesiology, Budapest, Hungary; Institute of Sport Sciences and Physical Education, University of Pécs, Hungary; Somogy County Kaposi Mór Teaching Hospital, Kaposvár, Hungary; Center for Human Movement Sciences, University of Groningen Medical Center, Groningen, the Netherlands
| | - Sandra Hunter
- Department of Physical Therapy, Marquette University, Milwaukee, WI, USA
| | - Marco Narici
- Neuromuscular Physiology Laboratory, Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Barbara Nicklas
- Section on Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, USA
| | - Thomas Roberts
- Department of Ecology and Evolutionary Biology, Brown University, USA
| | - Gregory Sawicki
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, USA
| | - Eleanor Simonsick
- Intramural Research Program of the National Institute on Aging, NIH, Baltimore, MD, USA
| | - Jane A Kent
- Department of Kinesiology, University of Massachusetts Amherst, MA, USA
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7
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Paris MT, McNeil CJ, Power GA, Rice CL, Dalton BH. Age-related performance fatigability: a comprehensive review of dynamic tasks. J Appl Physiol (1985) 2022; 133:850-866. [PMID: 35952347 DOI: 10.1152/japplphysiol.00319.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Adult ageing is associated with a myriad of changes within the neuromuscular system, leading to reductions in contractile function of old adults. One of the consequences of these age-related neuromuscular adaptations is altered performance fatigability, which can limit the ability of old adults to perform activities of daily living. Whereas age-related fatigability of isometric tasks has been well characterized, considerably less is known about fatigability of old adults during dynamic tasks involving movement about a joint, which provides a more functionally relevant task compared to static contractions. This review provides a comprehensive summary of age-related fatigability in dynamic contractions, where the importance of task specificity is highlighted with a brief discussion of the potential mechanisms responsible for differences in fatigability between young and old adults. The angular velocity of the task is critical for evaluating age-related fatigability, as tasks which constrain angular velocity (i.e., isokinetic) produce equivocal age-related differences in fatigability, whereas tasks involving unconstrained velocity (i.e., isotonic-like) consistently induce greater fatigability of old compared to young adults. These unconstrained velocity tasks, that are more closely associated with natural movements, offer an excellent model to uncover the underlying age-related mechanisms of increased fatigability. Future work evaluating the mechanisms of increased age-related fatigability of dynamic tasks should be evaluated using task-specific contractions (i.e., dynamic), particularly for assessment of spinal and supra-spinal components. Advancing our understanding of age-related fatigability is likely to yield novel insights and approaches for improving mobility limitations in old adults.
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Affiliation(s)
- Michael T Paris
- School of Kinesiology, University of Western Ontario, London, ON, Canada
| | - Chris J McNeil
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
| | - Geoffrey A Power
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Charles L Rice
- School of Kinesiology, University of Western Ontario, London, ON, Canada.,Department of Anatomy and Cell Biology, University of Western Ontario, London, ON, Canada
| | - Brian H Dalton
- School of Health and Exercise Science, University of British Columbia, Kelowna, BC, Canada
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