1
|
Inglis EC, Iannetta D, Rasica L, Mackie MZ, Keir DA, Macinnis MJ, Murias JM. Heavy-, Severe-, and Extreme-, but Not Moderate-Intensity Exercise Increase V̇o 2max and Thresholds after 6 wk of Training. Med Sci Sports Exerc 2024; 56:1307-1316. [PMID: 38376995 DOI: 10.1249/mss.0000000000003406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
INTRODUCTION This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O 2max ) and submaximal thresholds. METHODS Eighty-four young healthy participants (42 females, 42 males) were randomly assigned to six age, sex, and V̇O 2max -matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention. RESULTS Compared with the change in V̇O 2max (∆V̇O 2max ) in CON (0.1 ± 1.2 mL·kg -1 ·min -1 ), all training groups, except MOD (1.8 ± 2.7 mL·kg -1 ·min -1 ), demonstrated a significant increase ( P < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL·kg -1 ·min -1 ) followed by HVY2 (5.4 ± 2.3 mL·kg -1 ·min -1 ), SIT (4.7 ± 2.3 mL·kg -1 ·min -1 ), and HVY1 (3.3 ± 2.4 mL·kg -1 ·min -1 ), respectively. The ΔPO at the estimated lactate threshold ( θLT ) was similar across HVY1, HVY2, HIIT, and SIT, which were all greater than CON ( P < 0.05). The ΔV̇O 2 and ΔPO at θLT for MOD was not different from CON ( P > 0.05). HIIT produced the highest ΔPO at maximal metabolic steady state, which was greater than CON, MOD, and SIT ( P < 0.05). CONCLUSIONS This study demonstrated that i) exercise intensity is a key component determining changes in V̇O 2max and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals.
Collapse
Affiliation(s)
| | - Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, AB, CANADA
| | - Letizia Rasica
- Faculty of Kinesiology, University of Calgary, Calgary, AB, CANADA
| | - Mary Z Mackie
- Faculty of Kinesiology, University of Calgary, Calgary, AB, CANADA
| | - Daniel A Keir
- School of Kinesiology, Western University, London, ON, CANADA
| | | | | |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
do Nascimento Salvador PC, Nascimento EMF, Antunes D, Guglielmo LGA, Denadai BS. Energy metabolism and muscle activation heterogeneity explain V ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component and muscle fatigue of cycling at different intensities. Exp Physiol 2023; 108:503-517. [PMID: 36648072 PMCID: PMC10103881 DOI: 10.1113/ep090444] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 12/13/2022] [Indexed: 01/18/2023]
Abstract
NEW FINDINGS What is the central question of this study? What are the physiological mechanisms underlying muscle fatigue and the increase in the O2 cost per unit of work during high-intensity exercise? What is the main finding and its importance? Muscle fatigue happens before, and does not explain, theV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ), but they share the same origin. Muscle activation heterogeneity is associated with muscle fatigue andV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ . Knowing this may improve training prescriptions for healthy people leading to improved public health outcomes. ABSTRACT This study aimed to explain theV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ slow component (V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ ) and muscle fatigue during cycling at different intensities. The muscle fatigue of 16 participants was determined through maximal isokinetic effort lasting 3 s during constant work rate bouts of moderate (MOD), heavy (HVY) and very heavy intensity (VHI) exercise. Breath-by-breathV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ , near-infrared spectroscopy signals and EMG activity were analysed (thigh muscles).V ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ was higher during VHI exercise (∼70% vs. ∼28% ofV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ reserve in HVY). The deoxygenated haemoglobin final value during VHI exercise was higher than during HVY and MOD exercise (∼90% of HHb physiological normalization, vs. ∼82% HVY and ∼45% MOD). The muscle fatigue was greater after VHI exercise (∼22% vs. HVY ∼5%). There was no muscle fatigue after MOD exercise. The greatest magnitude of muscle fatigue occurred within 2 min (VHI ∼17%; HVY ∼9%), after which it stabilized. No significant relationship betweenV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ and muscle force production was observed. The τ of muscleV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ was significantly related (R2 = 0.47) with torque decrease for VHI. Type I and II muscle fibre recruitment mainly in the rectus femoris moderately explained the muscle fatigue (R2 = 0.30 and 0.31, respectively) and theV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ (R2 = 0.39 and 0.27, respectively). TheV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ is also partially explained by blood lactate accumulation (R2 = 0.42). In conclusion muscle fatigue and O2 cost seem to share the same physiological cause linked with a decrease in the muscleV ̇ O 2 ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}}$ and a change in lactate accumulation. Muscle fatigue andV ̇ O 2 sc ${\dot{V}}_{{{\rm{O}}}_{\rm{2}}{\rm{sc}}}$ are associated with muscle activation heterogeneity and metabolism of different muscles activated during cycling.
Collapse
Affiliation(s)
- Paulo Cesar do Nascimento Salvador
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
- Leonardo da Vinci University – Uniasselvi/VITRU EducationIndaialBrazil
| | | | - Diego Antunes
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
| | | | - Benedito Sérgio Denadai
- Physical effort LaboratorySports CentreFederal University of Santa CatarinaFlorianopolisBrazil
- Human Performance LaboratorySão Paulo State UniversityRio ClaroBrazil
| |
Collapse
|
4
|
Interaction of Factors Determining Critical Power. Sports Med 2023; 53:595-613. [PMID: 36622556 PMCID: PMC9935749 DOI: 10.1007/s40279-022-01805-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2022] [Indexed: 01/10/2023]
Abstract
The physiological determinants of high-intensity exercise tolerance are important for both elite human performance and morbidity, mortality and disease in clinical settings. The asymptote of the hyperbolic relation between external power and time to task failure, critical power, represents the threshold intensity above which systemic and intramuscular metabolic homeostasis can no longer be maintained. After ~ 60 years of research into the phenomenon of critical power, a clear understanding of its physiological determinants has emerged. The purpose of the present review is to critically examine this contemporary evidence in order to explain the physiological underpinnings of critical power. Evidence demonstrating that alterations in convective and diffusive oxygen delivery can impact upon critical power is first addressed. Subsequently, evidence is considered that shows that rates of muscle oxygen utilisation, inferred via the kinetics of pulmonary oxygen consumption, can influence critical power. The data reveal a clear picture that alterations in the rates of flux along every step of the oxygen transport and utilisation pathways influence critical power. It is also clear that critical power is influenced by motor unit recruitment patterns. On this basis, it is proposed that convective and diffusive oxygen delivery act in concert with muscle oxygen utilisation rates to determine the intracellular metabolic milieu and state of fatigue within the myocytes. This interacts with exercising muscle mass and motor unit recruitment patterns to ultimately determine critical power.
Collapse
|
5
|
Eck BL, Yang M, Elias JJ, Winalski CS, Altahawi F, Subhas N, Li X. Quantitative MRI for Evaluation of Musculoskeletal Disease: Cartilage and Muscle Composition, Joint Inflammation, and Biomechanics in Osteoarthritis. Invest Radiol 2023; 58:60-75. [PMID: 36165880 PMCID: PMC10198374 DOI: 10.1097/rli.0000000000000909] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
ABSTRACT Magnetic resonance imaging (MRI) is a valuable tool for evaluating musculoskeletal disease as it offers a range of image contrasts that are sensitive to underlying tissue biochemical composition and microstructure. Although MRI has the ability to provide high-resolution, information-rich images suitable for musculoskeletal applications, most MRI utilization remains in qualitative evaluation. Quantitative MRI (qMRI) provides additional value beyond qualitative assessment via objective metrics that can support disease characterization, disease progression monitoring, or therapy response. In this review, musculoskeletal qMRI techniques are summarized with a focus on techniques developed for osteoarthritis evaluation. Cartilage compositional MRI methods are described with a detailed discussion on relaxometric mapping (T 2 , T 2 *, T 1ρ ) without contrast agents. Methods to assess inflammation are described, including perfusion imaging, volume and signal changes, contrast-enhanced T 1 mapping, and semiquantitative scoring systems. Quantitative characterization of structure and function by bone shape modeling and joint kinematics are described. Muscle evaluation by qMRI is discussed, including size (area, volume), relaxometric mapping (T 1 , T 2 , T 1ρ ), fat fraction quantification, diffusion imaging, and metabolic assessment by 31 P-MR and creatine chemical exchange saturation transfer. Other notable technologies to support qMRI in musculoskeletal evaluation are described, including magnetic resonance fingerprinting, ultrashort echo time imaging, ultrahigh-field MRI, and hybrid MRI-positron emission tomography. Challenges for adopting and using qMRI in musculoskeletal evaluation are discussed, including the need for metal artifact suppression and qMRI standardization.
Collapse
Affiliation(s)
- Brendan L. Eck
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Imaging Instute, Cleveland Clinic, Cleveland, OH, USA
| | - Mingrui Yang
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - John J. Elias
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Department of Research, Cleveland Clinic Akron General, Akron, OH, USA
| | - Carl S. Winalski
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Imaging Instute, Cleveland Clinic, Cleveland, OH, USA
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Faysal Altahawi
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Imaging Instute, Cleveland Clinic, Cleveland, OH, USA
| | - Naveen Subhas
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Imaging Instute, Cleveland Clinic, Cleveland, OH, USA
| | - Xiaojuan Li
- Program of Advanced Musculoskeletal Imaging, Cleveland Clinic, Cleveland, OH, USA
- Imaging Instute, Cleveland Clinic, Cleveland, OH, USA
- Department of Biomedical Engineering, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| |
Collapse
|
6
|
Martínez-Noguera FJ, Alcaraz PE, Carlos-Vivas J, Marín-Pagán C. Chronic Supplementation of 2S-Hesperidin Improves Acid-Base Status and Decreases Lactate at FatMax, at Ventilatory Threshold 1 and 2 and after an Incremental Test in Amateur Cyclists. BIOLOGY 2022; 11:biology11050736. [PMID: 35625464 PMCID: PMC9138540 DOI: 10.3390/biology11050736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/29/2022] [Accepted: 05/06/2022] [Indexed: 11/30/2022]
Abstract
Simple Summary Currently, hesperidin is a molecule found mainly in citrus fruits and is being widely researched in the area of chronic disease, but also in the field of sports nutrition. Some studies have shown its antioxidant, anti-inflammatory, lipid and carbohydrate metabolism modulating effects, including the enhancement of nitric oxide synthesis. However, few human studies have demonstrated a positive effect of hesperidin intake, in particular 2S-hesperidin, on sports performance, particularly in anaerobic and aerobic tests. However, the biochemical mechanisms that may be responsible for this enhanced performance have not yet been described. Therefore, one of the aims of this study was to assess whether an eight-week intake of 2S-hesperidin can improve acid-base status and metabolic status (lactate and glucose) in an incremental test in amateur cyclists. The results showed that amateur cyclists chronically supplemented with 2S-hesperidin improved acid-base status and lactate at FatMax, ventilatory thresholds 1 and 2, and in the acute phase of recovery after maximal effort. Abstract Chronic supplementation with 2S-hesperidin improves performance; however, the mechanisms underlying this effect have not yet been explored. Therefore, the aim of this study was to assess whether changes in acid-base status may be associated with improved performance after 2S-hesperidin supplementation compared to microcellulose (placebo). Forty amateur cyclists (n = 20 per group) underwent a rectangular test where capillary blood samples were taken at baseline, FatMax1, VT1, VT2, PMAX, FatMax2 and EPOC to measure acid-base parameters. After eight weeks of 2S-hesperidin supplementation (500 mg/d) increased HCO3−, SBC, ABE (p ≤ 0.05) and decreased Lac were found at FatMax1, VT1, FatMax2 and EPOC (p ≤ 0.05), while decreased Lac at VT2 was found with a large effect size (ES = 1.15) compared to placebo. Significant group differences in the area under the curve were observed when comparing pre-post-intervention pH changes (p = 0.02) between groups. Chronic supplementation with 2S-hesperidin improved acid-base status and Lac, both at low-moderate and submaximal intensities, improving recovery after exercise-to-exhaustion in amateur cyclists.
Collapse
Affiliation(s)
- Francisco Javier Martínez-Noguera
- Research Center for High Performance Sport, Catholic University of Murcia (UCAM), Campus de los Jerónimos Nº 135, 30107 Murcia, Spain; (P.E.A.); (C.M.-P.)
- Correspondence: ; Tel.: +34-968-278-566
| | - Pedro E. Alcaraz
- Research Center for High Performance Sport, Catholic University of Murcia (UCAM), Campus de los Jerónimos Nº 135, 30107 Murcia, Spain; (P.E.A.); (C.M.-P.)
| | - Jorge Carlos-Vivas
- Health, Economy, Motricity and Education Research Group (HEME), Faculty of Sport Sciences, University of Extremadura, Avda. de Elvas, s/n., 06006 Badajoz, Spain;
| | - Cristian Marín-Pagán
- Research Center for High Performance Sport, Catholic University of Murcia (UCAM), Campus de los Jerónimos Nº 135, 30107 Murcia, Spain; (P.E.A.); (C.M.-P.)
| |
Collapse
|
7
|
Davies MJ, Lyall GK, Benson AP, Cannon DT, Birch KM, Rossiter HB, Ferguson C. Power Reserve at Intolerance in Ramp-Incremental Exercise Is Dependent on Incrementation Rate. Med Sci Sports Exerc 2021; 53:1606-1614. [PMID: 34261991 DOI: 10.1249/mss.0000000000002645] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
INTRODUCTION The mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown. METHODS In twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min-1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout. RESULTS Baseline Piso was not different among RI rates (analysis of variance; P > 0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P < 0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P > 0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P < 0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P < 0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P > 0.05), thus there was no "power reserve." In RI-10, Piso was greater than RI peak power at intolerance (P < 0.001), that is, there was a "power reserve." CONCLUSIONS In RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.
Collapse
Affiliation(s)
- Matthew J Davies
- School of Biomedical Sciences, Faculty of Biological Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UNITED KINGDOM
| | - Gemma K Lyall
- School of Biomedical Sciences, Faculty of Biological Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UNITED KINGDOM
| | - Alan P Benson
- School of Biomedical Sciences, Faculty of Biological Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UNITED KINGDOM
| | - Daniel T Cannon
- School of Exercise and Nutritional Sciences, San Diego State University, San Diego, CA
| | - Karen M Birch
- School of Biomedical Sciences, Faculty of Biological Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UNITED KINGDOM
| | | | - Carrie Ferguson
- School of Biomedical Sciences, Faculty of Biological Sciences and Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds, UNITED KINGDOM
| |
Collapse
|
8
|
Affiliation(s)
- Harry B Rossiter
- Rehabilitation Clinical Trials Center, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA; and Faculty of Biological Sciences, University of Leeds, Leeds, UNITED KINGDOM
| |
Collapse
|
9
|
Pethick J, Winter SL, Burnley M. Physiological Evidence That the Critical Torque Is a Phase Transition, Not a Threshold. Med Sci Sports Exerc 2021; 52:2390-2401. [PMID: 32366801 PMCID: PMC7556242 DOI: 10.1249/mss.0000000000002389] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Introduction Distinct physiological responses to exercise occur in the heavy- and severe-intensity domains, which are separated by the critical power or critical torque (CT). However, how the transition between these intensity domains actually occurs is not known. We tested the hypothesis that CT is a sudden threshold, with no gradual transition from heavy- to severe-intensity behavior within the confidence limits associated with the CT. Methods Twelve healthy participants performed four exhaustive severe-intensity trials for the determination of CT, and four 30-min trials in close proximity to CT (one or two SE above or below each participant’s CT estimate; CT − 2, CT − 1, CT + 1, CT + 2). Muscle O2 uptake, rectified electromyogram, and torque variability and complexity were monitored throughout each trial, and maximal voluntary contractions (MVC) with femoral nerve stimulation were performed before and after each trial to determine central and peripheral fatigue responses. Results The rates of change in fatigue-related variables, muscle O2 uptake, electromyogram amplitude, and torque complexity were significantly faster in the severe trials compared with CT − 2. For example, the fall in MVC torque was −1.5 ± 0.8 N·m·min−1 in CT − 2 versus –7.9 ± 2.5 N·m·min−1 in the lowest severe-intensity trial (P < 0.05). Individual analyses showed a low frequency of severe responses even in the circa-CT trials ostensibly above the CT, but also the rare appearance of severe-intensity responses in all circa-CT trials. Conclusions These data demonstrate that the transition between heavy- and severe-intensity exercise occurs gradually rather than suddenly.
Collapse
Affiliation(s)
- Jamie Pethick
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Kent, UNITED KINGDOM
| | | | | |
Collapse
|
10
|
Evaluating the Accuracy of Using Fixed Ranges of METs to Categorize Exertional Intensity in a Heterogeneous Group of Healthy Individuals: Implications for Cardiorespiratory Fitness and Health Outcomes. Sports Med 2021; 51:2411-2421. [PMID: 33900580 DOI: 10.1007/s40279-021-01476-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/08/2021] [Indexed: 12/28/2022]
Abstract
BACKGROUND Appropriate quantification of exertional intensity remains elusive. OBJECTIVE To compare, in a large and heterogeneous cohort of healthy females and males, the commonly used intensity classification system (i.e., light, moderate, vigorous, near-maximal) based on fixed ranges of metabolic equivalents (METs) to an individualized schema based on the exercise intensity domains (i.e., moderate, heavy, severe). METHODS A heterogenous sample of 565 individuals (females 165; males 400; age range 18-83 years old) were included in the study. Individuals performed a ramp-incremental exercise test from which gas exchange threshold (GET), respiratory compensation point (RCP) and maximum oxygen uptake (VO2max) were determined to build the exercise intensity domain schema (moderate = METs ≤ GET; heavy = METs > GET but ≤ RCP; severe = METs > RCP) for each individual. Pearson's chi-square tests over contingency tables were used to evaluate frequency distribution within intensity domains at each MET value. A multi-level regression model was performed to identify predictors of the amplitude of the exercise intensity domains. RESULTS A critical discrepancy existed between the confines of the exercise intensity domains and the commonly used fixed MET classification system. Overall, the upper limit of the moderate-intensity domain ranged between 2 and 13 METs and of the heavy-intensity domain between 3 and 18 METs, whereas the severe-intensity domain included METs from 4 onward. CONCLUSIONS Findings show that the common practice of assigning fixed values of METs to relative categories of intensity risks misclassifications of the physiological stress imposed by exercise and physical activity. These misclassifications can lead to erroneous interpretations of the dose-response relationship of exercise and physical activity.
Collapse
|
11
|
Goulding RP, Marwood S, Okushima D, Poole DC, Barstow TJ, Lei TH, Kondo N, Koga S. Effect of priming exercise and body position on pulmonary oxygen uptake and muscle deoxygenation kinetics during cycle exercise. J Appl Physiol (1985) 2020; 129:810-822. [PMID: 32758041 DOI: 10.1152/japplphysiol.00478.2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
We hypothesized that the performance of prior heavy exercise would speed pulmonary oxygen uptake (V̇o2) kinetics (i.e., as described by the time constant, [Formula: see text]) and reduce the amplitude of muscle deoxygenation (deoxy[heme]) kinetics in the supine (S) but not upright (U) body position. Seventeen healthy men completed heavy-intensity constant-work rate exercise tests in S and U consisting of two bouts of 6-min cycling separated by 6-min cycling at 20 W. Pulmonary V̇o2 was measured breath by breath; total and deoxy[heme] were determined via time-resolved near-infrared spectroscopy (NIRS) at three muscle sites. Priming exercise reduced [Formula: see text] in S (bout 1: 36 ± 10 vs. bout 2: 28 ± 10 s, P < 0.05) but not U (bout 1: 27 ± 8 s vs. bout 2: 25 ± 7 s, P > 0.05). Deoxy[heme] amplitude was increased after priming in S (bout 1: 25-28 μM vs. bout 2: 30-35 μM, P < 0.05) and U (bout 1: 13-18 μM vs. bout 2: 17-25 μM, P > 0.05), whereas baseline total[heme] was enhanced in S (bout 1: 110-179 μM vs. bout 2: 121-193 μM, P < 0.05) and U (bout 1: 123-186 μM vs. bout 2: 137-197 μM, P < 0.05). Priming exercise increased total[heme] in both S and U, likely indicating enhanced diffusive O2 delivery. However, the observation that after priming the amplitude of the deoxy[heme] response was increased in S suggests that the reduction in [Formula: see text] subsequent to priming was related to a combination of both enhanced intracellular O2 utilization and increased O2 delivery.NEW & NOTEWORTHY Here we show that oxygen uptake (V̇o2) kinetics are slower in the supine compared with upright body position, an effect that is associated with an increased amplitude of skeletal muscle deoxygenation in the supine position. After priming in the supine position, the amplitude of muscle deoxygenation remained markedly elevated above that observed during upright exercise. Hence, the priming effect cannot be solely attributed to enhanced O2 delivery, and enhancements to intracellular O2 utilization must also be contributory.
Collapse
Affiliation(s)
- Richie P Goulding
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan.,Japan Society for Promotion of Science, Tokyo, Japan
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| | - Dai Okushima
- Osaka International University, Moriguchi, Japan
| | - David C Poole
- Department of Anatomy and Physiology and Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Department of Anatomy and Physiology and Department of Kinesiology, Kansas State University, Manhattan, Kansas
| | - Tze-Huan Lei
- Japan Society for Promotion of Science, Tokyo, Japan.,Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| |
Collapse
|
12
|
Goulding RP, Roche DM, Scott SN, Koga S, Weston PJ, Marwood S. Limitations to exercise tolerance in type 1 diabetes: the role of pulmonary oxygen uptake kinetics and priming exercise. J Appl Physiol (1985) 2020; 128:1299-1309. [PMID: 32213117 DOI: 10.1152/japplphysiol.00892.2019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We compared the time constant (τV̇O2) of the fundamental phase of pulmonary oxygen uptake (V̇o2) kinetics between young adult men with type 1 diabetes and healthy control subjects. We also assessed the impact of priming exercise on τV̇O2, critical power, and muscle deoxygenation in a subset of participants with type 1 diabetes. Seventeen men with type 1 diabetes and 17 healthy male control subjects performed moderate-intensity exercise to determine τV̇O2. A subset of seven participants with type 1 diabetes performed an additional eight visits, in which critical power, τV̇O2, and muscle deoxyhemoglobin + myoglobin ([HHb+Mb], via near-infrared spectroscopy) kinetics (described by a time constant, τ[HHb+Mb]) were determined with (PRI) and without (CON) a prior 6-min bout of heavy exercise. τV̇O2 was greater in participants with type 1 diabetes compared with control subjects (type 1 diabetes 50 ± 13 vs. control 32 ± 12 s; P < 0.001). Critical power was greater in PRI compared with CON (PRI 161 ± 25 vs. CON 149 ± 22 W; P < 0.001), whereas τV̇O2 (PRI 36 ± 15 vs. CON 50 ± 21 s; P = 0.006) and τ[HHb+Mb] (PRI 10 ± 5 vs. CON 17 ± 11 s; P = 0.037) were reduced in PRI compared with CON. Type 1 diabetes patients showed slower pulmonary V̇o2 kinetics compared with control subjects; priming exercise speeded V̇o2 and [HHb + Mb] kinetics and increased critical power in a subgroup with type 1 diabetes. These data therefore represent the first characterization of the power-duration relationship in type 1 diabetes and the first experimental evidence that τV̇O2 is an independent determinant of critical power in this population.NEW & NOTEWORTHY Patients with type 1 diabetes demonstrated slower oxygen uptake (V̇o2) kinetics compared with healthy control subjects. Furthermore, a prior bout of high-intensity exercise speeded V̇o2 kinetics and increased critical power in people with type 1 diabetes. Prior exercise speeded muscle deoxygenation kinetics, indicating that V̇o2 kinetics in type 1 diabetes are limited primarily by oxygen extraction and/or intracellular factors. These findings highlight the potential for interventions that decrease metabolic inertia for enhancing exercise tolerance in this condition.
Collapse
Affiliation(s)
- Richie P Goulding
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom.,Japan Society for Promotion of Science, Tokyo, Japan.,Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Denise M Roche
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| | - Sam N Scott
- University Department of Diabetes, Endocrinology, Nutritional Medicine, and Metabolism, University Hospital and University of Bern, Bern, Switzerland.,Team Novo Nordisk Professional Cycling Team, Atlanta, Georgia
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Philip J Weston
- Royal Liverpool and Broadgreen University Hospitals NHS Trust, Liverpool, United Kingdom
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, United Kingdom
| |
Collapse
|
13
|
Okushima D, Poole DC, Barstow TJ, Kondo N, Chin LMK, Koga S. Effect of differential muscle activation patterns on muscle deoxygenation and microvascular haemoglobin regulation. Exp Physiol 2020; 105:531-541. [PMID: 31944446 PMCID: PMC10466155 DOI: 10.1113/ep088322] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Accepted: 01/14/2020] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does the presence and extent of heterogeneity in the ratio of O2 delivery to uptake across human muscles relate specifically to different muscle activation patterns? What is the main finding and its importance? During ramp incremental knee-extension and cycling exercise, the profiles of muscle deoxygenation (deoxy[haemoglobin + myoglobin]) and diffusive O2 potential (total[haemoglobin + myoglobin]) in the vastus lateralis corresponded to different muscle activation strategies. However, this was not the case for the rectus femoris, where muscle activation and deoxygenation profiles were dissociated and might therefore be determined by other structural and/or functional attributes (e.g. arteriolar vascular regulation and control of red blood cell flux). ABSTRACT Near-infrared spectroscopy has revealed considerable heterogeneity in the ratio of O2 delivery to uptake as identified by disparate deoxygenation {deoxy[haemoglobin + myoglobin] (deoxy[Hb + Mb])} values in the exercising quadriceps. However, whether this represents a recruitment phenomenon or contrasting vascular and metabolic control, as seen among fibre types, has not been established. We used knee-extension (KE) and cycling (CE) incremental exercise protocols to examine whether differential muscle activation profiles could account for the heterogeneity of deoxy[Hb + Mb] and microvascular haemoconcentration (i.e. total[Hb + Mb]). Using time-resolved near-infrared spectroscopy for the quadriceps femoris (vastus lateralis and rectus femoris) during exhaustive ramp exercise in eight participants, we tested the following hypotheses: (i) the deoxy[Hb + Mb] (i.e. fractional O2 extraction) would relate to muscle activation levels across exercise protocols; and (ii) KE would induce greater total[Hb + Mb] (i.e. diffusive O2 potential) at task failure (i.e. peak O2 uptake) than CE irrespective of muscle site. At a given level of muscle activation, as assessed by the relative integrated EMG normalized to maximal voluntary contraction (%iEMGmax ), the vastus lateralis deoxy[Hb + Mb] profile was not different between exercise protocols. However, at peak O2 uptake and until 20% iEMGmax for CE, rectus femoris exhibited a lower deoxy[Hb + Mb] (83.2 ± 15.5 versus 98.2 ± 19.4 μm) for KE than for CE (P < 0.05). The total[Hb + Mb] at peak O2 uptake was not different between exercise protocols for either muscle site. These data support the hypothesis that the contrasting patterns of convective and diffusive O2 transport correspond to different muscle activation patterns in vastus lateralis but not rectus femoris. Thus, the differential deoxygenation profiles for rectus femoris across exercise protocols might be dependent upon specific facets of muscle architecture and functional haemodynamic events.
Collapse
Affiliation(s)
- Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan
- Research Fellow of Japan Society for the Promotion of Science, Tokyo, Japan
- Osaka International University, Moriguchi, Japan
| | - David C. Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Thomas J. Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | | | - Lisa M. K. Chin
- Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, Maryland
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan
| |
Collapse
|
14
|
Evaluating the NIRS-derived microvascular O2 extraction "reserve" in groups varying in sex and training status using leg blood flow occlusions. PLoS One 2019; 14:e0220192. [PMID: 31344091 PMCID: PMC6658081 DOI: 10.1371/journal.pone.0220192] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 07/10/2019] [Indexed: 02/04/2023] Open
Abstract
It has been demonstrated that the plateau in the near-infrared spectroscopy (NIRS) derived deoxygenated hemoglobin and myoglobin (deoxy[Hb+Mb]) signal (i.e., deoxy[Hb+Mb]PLATEAU) towards the end of a ramp-incremental (RI) test does not represent the upper-limit in O2 extraction of the vastus lateralis (VL) muscle, given that an O2 extraction reserve has been recently observed. This study aimed to investigate whether this O2 extraction reserve was present in various populations and whether it exhibited sex- and/or training- related differences.Sixteen men- 8 untrained (27±5 years; 83±11 kg; 179±9 cm), 8 trained (27±4 years; 82±10 kg; 182±8 cm) and 9 trained women (27±2 years; 66±10 kg; 172±6 cm) performed a RI cycling test to exhaustion. The NIRS-derived deoxy[Hb+Mb] signal was measured continuously on the VL as a proxy for O2 extraction. A leg blood flow occlusion (i.e., ischemia) was performed at rest (LBFOCC 1) and immediately post the RI test (LBFOCC 2).No significant difference was found between the deoxy[Hb+Mb] amplitude during LBFOCC 1 and the deoxy[Hb+Mb]PLATEAU (p>0.05) nor between baseline (bsln) deoxy[Hb+Mb] values. deoxy[Hb+Mb] amplitude during LBFOCC 2 was significantly greater than LBFOCC 1 and at deoxy[Hb+Mb]PLATEAU (p<0.05) with group means ~30-45% higher than the deoxy[Hb+Mb]PLATEAU and LBFOCC 1 (p<0.05). No significant differences were found between groups in O2 extraction reserve, regardless of sex- or training-statusThe results of this study demonstrated the existence of an O2 extraction reserve in different populations, and that neither sex- nor training-related differences affect the amplitude of the reserve.
Collapse
|
15
|
Oza PD, Dudley-Javoroski S, Shields RK. Sustained submaximal contraction yields biphasic modulation of soleus Post-activation depression in healthy humans. Scand J Med Sci Sports 2019; 29:944-951. [PMID: 30892718 DOI: 10.1111/sms.13421] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 02/01/2019] [Accepted: 03/14/2019] [Indexed: 12/23/2022]
Abstract
The amplitude of the H-reflex during the development and progression of fatigue reflects a complex interplay between central and peripheral factors. The purpose of this study is to characterize H-reflex homosynaptic post-activation depression (PAD) in an online fashion during a sustained submaximal fatigue task. The task required a high motor output in order to increase the likelihood of creating partial muscle ischemia with accumulation of fatigue metabolites, an important potential inhibitory influence upon the H-reflex during the progression of fatigue. Eleven subjects without neurologic impairment maintained volitional, isometric plantar flexion at 60% of maximal voluntary contraction until exhaustion. A paired-pulse stimulus (2 Hz) was delivered to the tibial nerve to elicit paired H-reflexes before, during, and after the fatigue protocol. The normalized amplitude of the second H-reflex (depression ratio) served as an estimate of PAD. Depression ratio increased during the first half of the fatigue protocol (P < 0.001), indicating a diminution of PAD, and then returned as exhaustion approached. The biphasic behavior of homosynaptic H-reflex depression during fatigue to exhaustion suggests a role for metabolic mediators of post-activation depression during fatigue.
Collapse
Affiliation(s)
- Preeti D Oza
- Department of Physical Therapy, University of the Pacific, Stockton, California
| | - Shauna Dudley-Javoroski
- Department of Physical Therapy Rehabilitation Science, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| | - Richard K Shields
- Department of Physical Therapy Rehabilitation Science, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, Iowa
| |
Collapse
|
16
|
Iannetta D, Okushima D, Inglis EC, Kondo N, Murias JM, Koga S. Blood flow occlusion-related O2 extraction “reserve” is present in different muscles of the quadriceps but greater in deeper regions after ramp-incremental test. J Appl Physiol (1985) 2018; 125:313-319. [DOI: 10.1152/japplphysiol.00154.2018] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
It was recently demonstrated that an O2 extraction reserve, as assessed by the near-infrared spectroscopy (NIRS)-derived deoxygenation signal ([HHb]), exists in the superficial region of vastus lateralis (VL) muscle during an occlusion performed at the end of a ramp-incremental test. However, it is unknown whether this reserve is present and/or different in magnitude in other portions and depths of the quadriceps muscles. We tested the hypothesis that an O2 extraction reserve would exist in other regions of this muscle but is greater in deep compared with more superficial portions. Superficial (VL-s) and deep VL (VL-d) as well as superficial rectus femoris (RF-s) were monitored by a combination of low- and high-power time-resolved (TRS) NIRS. During the occlusion immediately post-ramp-incremental test there was a significant overshoot in the [HHb] signal ( P < 0.05). However, the magnitude of this increase was greater in VL-d (93.2 ± 42.9%) compared with VL-s (55.0 ± 19.6%) and RF-s (47.8 ± 14.0%) ( P < 0.05). The present study demonstrated that an O2 extraction reserve exists in different pools of active muscle fibers of the quadriceps at the end of a ramp exercise to exhaustion. The greater magnitude in the reserve observed in the deeper portion of VL, however, suggests that this portion of muscle may present a greater surplus of oxygenated blood, which is likely due to a greater population of slow-twitch fibers. These findings add to the notion that the plateau in the [HHb] signal toward the end of a ramp-incremental exercise does not indicate the upper limit of O2 extraction. NEW & NOTEWORTHY Different portions of the quadriceps muscles exhibited an untapped O2 extraction reserve during a blood flow occlusion performed at the end of a ramp-incremental exercise. In the deeper portion of the vastus lateralis muscle, this reserve was greater compared with superficial vastus lateralis and rectus femoris. These data suggest that the O2 extraction reserve may be dependent on the vascular and/or oxidative capacities of the muscles.
Collapse
Affiliation(s)
- Danilo Iannetta
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | | | | | | | - Juan M Murias
- Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada
| | | |
Collapse
|
17
|
Koga S, Okushima D, Barstow TJ, Rossiter HB, Kondo N, Poole DC. Near-infrared spectroscopy of superficial and deep rectus femoris reveals markedly different exercise response to superficial vastus lateralis. Physiol Rep 2018; 5:5/17/e13402. [PMID: 28912130 PMCID: PMC5599862 DOI: 10.14814/phy2.13402] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2017] [Revised: 08/08/2017] [Accepted: 08/08/2017] [Indexed: 12/13/2022] Open
Abstract
To date our knowledge of skeletal muscle deoxygenation as measured by near-infrared spectroscopy (NIRS) is predicated almost exclusively on sampling of superficial muscle(s), most commonly the vastus lateralis (VL-s). Recently developed high power NIRS facilitates simultaneous sampling of deep (i.e., rectus femoris, RF-d) and superficial muscles of RF (RF-s) and VL-s. Because deeper muscle is more oxidative with greater capillarity and sustains higher blood flows than superficial muscle, we used time-resolved NIRS to test the hypotheses that, following exercise onset, the RF-d has slower deoxy[Hb+Mb] kinetics with reduced amplitude than superficial muscles. Thirteen participants performed cycle exercise transitions from unloaded to heavy work rates. Within the same muscle (RF-s vs. RF-d) deoxy[Hb+Mb] kinetics (mean response time, MRT) and amplitudes were not different. However, compared with the kinetics of VL-s, deoxy[Hb+Mb] of RF-s and RF-d were slower (MRT: RF-s, 51 ± 23; RF-d, 55 ± 29; VL-s, 18 ± 6 s; P < 0.05). Moreover, the amplitude of total[Hb+Mb] was greater for VL-s than both RF-s and RF-d (P < 0.05). Whereas pulmonary V˙O2 kinetics (i.e., on vs. off) were symmetrical in heavy exercise, there was a marked on-off asymmetry of deoxy[Hb+Mb] for all three sites i.e., MRT-off > MRT-on (P < 0.05). Collectively these data reveal profoundly different O2 transport strategies, with the RF-s and RF-d relying proportionately more on elevated perfusive and the VL-s on diffusive O2 transport. These disparate O2 transport strategies and their temporal profiles across muscles have previously been concealed within the "global" pulmonary V˙O2 response.
Collapse
Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Thomas J Barstow
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California.,Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Narihiko Kondo
- Applied Physiology Laboratory, Kobe University, Kobe, Japan
| | - David C Poole
- Departments of Anatomy and Physiology, and Kinesiology, Kansas State University, Manhattan, Kansas
| |
Collapse
|
18
|
Okushima D, Poole DC, Barstow TJ, Rossiter HB, Kondo N, Bowen TS, Amano T, Koga S. Greater V˙O2peak is correlated with greater skeletal muscle deoxygenation amplitude and hemoglobin concentration within individual muscles during ramp-incremental cycle exercise. Physiol Rep 2018; 4:4/23/e13065. [PMID: 27986837 PMCID: PMC5260088 DOI: 10.14814/phy2.13065] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 11/03/2016] [Indexed: 11/24/2022] Open
Abstract
It is axiomatic that greater aerobic fitness (V˙O2peak) derives from enhanced perfusive and diffusive O2 conductances across active muscles. However, it remains unknown how these conductances might be reflected by regional differences in fractional O2 extraction (i.e., deoxy [Hb+Mb] and tissue O2 saturation [StO2]) and diffusive O2 potential (i.e., total[Hb+Mb]) among muscles spatially heterogeneous in blood flow, fiber type, and recruitment (vastus lateralis, VL; rectus femoris, RF). Using quantitative time‐resolved near‐infrared spectroscopy during ramp cycling in 24 young participants (V˙O2peak range: ~37.4–66.4 mL kg−1 min−1), we tested the hypotheses that (1) deoxy[Hb+Mb] and total[Hb+Mb] at V˙O2peak would be positively correlated with V˙O2peak in both VL and RF muscles; (2) the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) during submaximal exercise would not differ among subjects differing in V˙O2peak. Peak deoxy [Hb+Mb] and StO2 correlated with V˙O2peak for both VL (r = 0.44 and −0.51) and RF (r = 0.49 and −0.49), whereas for total[Hb+Mb] this was true only for RF (r = 0.45). Baseline deoxy[Hb+Mb] and StO2 correlated with V˙O2peak only for RF (r = −0.50 and 0.54). In addition, the deoxy[Hb+Mb] slopes were not affected by aerobic fitness. In conclusion, while the pattern of deoxygenation (the deoxy[Hb+Mb] slopes) did not differ between fitness groups the capacity to deoxygenate [Hb+Mb] (index of maximal fractional O2 extraction) correlated significantly with V˙O2peak in both RF and VL muscles. However, only in the RF did total[Hb+Mb] (index of diffusive O2 potential) relate to fitness.
Collapse
Affiliation(s)
- Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Thomas J Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | - Narihiko Kondo
- Laboratory for Applied Human Physiology, Graduate School of Human Development and Environment Kobe University, Kobe, Japan
| | - T Scott Bowen
- Department of Internal Medicine & Cardiology, Heart Center, Leipzig University, Leipzig, Germany
| | - Tatsuro Amano
- Faculty of Education Niigata University, Niigata, Japan
| | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| |
Collapse
|
19
|
Karatzaferi C, Adamek N, Geeves MA. Modulators of actin-myosin dissociation: basis for muscle type functional differences during fatigue. Am J Physiol Cell Physiol 2017; 313:C644-C654. [PMID: 28931538 PMCID: PMC5814585 DOI: 10.1152/ajpcell.00023.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The muscle types present with variable fatigue tolerance, in part due to the myosin isoform expressed. However, the critical steps that define “fatigability” in vivo of fast vs. slow myosin isoforms, at the molecular level, are not yet fully understood. We examined the modulation of the ATP-induced myosin subfragment 1 (S1) dissociation from pyrene-actin by inorganic phosphate (Pi), pH, and temperature using a specially modified stopped-flow system that allowed fast kinetics measurements at physiological temperature. We contrasted the properties of rabbit psoas (fast) and bovine masseter (slow) myosins (obtained from samples collected from New Zealand rabbits and from a licensed abattoir, respectively, according to institutional and national ethics permits). To identify ATP cycling biochemical intermediates, we assessed ATP binding to a preequilibrated mixture of actomyosin and variable [ADP], pH (pH 7 vs. pH 6.2), and Pi (zero, 15, or 30 added mM Pi) in a range of temperatures (5 to 45°C). Temperature and pH variations had little, if any, effect on the ADP dissociation constant (KADP) for fast S1, but for slow S1, KADP was weakened with increasing temperature or low pH. In the absence of ADP, the dissociation constant for phosphate (KPi) was weakened with increasing temperature for fast S1. In the presence of ADP, myosin type differences were revealed at the apparent phosphate affinity, depending on pH and temperature. Overall, the newly revealed kinetic differences between myosin types could help explain the in vivo observed muscle type functional differences at rest and during fatigue.
Collapse
Affiliation(s)
- Christina Karatzaferi
- Muscle Physiology and Mechanics Group, DPESS, University of Thessaly, Trikala, Greece.,Experimental Myology and Integrative Physiology Cluster, FSHS, University of St Mark and St John , Plymouth , United Kingdom
| | - Nancy Adamek
- School of Biosciences, University of Kent, Kent, United Kingdom
| | | |
Collapse
|
20
|
Osawa T, Arimitsu T, Takahashi H. Hypoxia affects tissue oxygenation differently in the thigh and calf muscles during incremental running. Eur J Appl Physiol 2017; 117:2057-2064. [PMID: 28819691 DOI: 10.1007/s00421-017-3696-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Accepted: 08/04/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE The present study was performed to determine the impact of hypoxia on working muscle oxygenation during incremental running, and to compare tissue oxygenation between the thigh and calf muscles. METHODS Nine distance runners and triathletes performed incremental running tests to exhaustion under normoxic and hypoxic conditions (fraction of inspired oxygen = 0.15). Peak pulmonary oxygen uptake ([Formula: see text]) and tissue oxygen saturation (StO2) were measured simultaneously in both the vastus lateralis and medial gastrocnemius. RESULTS Hypoxia significantly decreased peak running speed and [Formula: see text] (p < 0.01). During incremental running, StO2 in the vastus lateralis decreased almost linearly, and the rate of decrease from warm-up (180 m min-1) to [Formula: see text] was significantly greater than in the medial gastrocnemius under both normoxic and hypoxic conditions (p < 0.01). StO2 in both muscles was significantly decreased under hypoxic compared with normoxic conditions at all running speeds (p < 0.01). The rate at which StO2 was decreased by hypoxia was greater in the vastus lateralis as the running speed increased, whereas it changed little in the medial gastrocnemius. CONCLUSIONS These results suggest that the thigh is more deoxygenated than the calf under hypoxic conditions, and that the effects of hypoxia on tissue oxygenation differ between these two muscles during incremental running.
Collapse
Affiliation(s)
- Takuya Osawa
- COI Project Center, Juntendo University, 1-1, Hiraga-gakuendai, Inzai-shi, Chiba, Japan. .,Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan.
| | - Takuma Arimitsu
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan.,Faculty of Sport and Health Science, Ritsumeikan University, Shiga, Japan
| | - Hideyuki Takahashi
- Department of Sports Science, Japan Institute of Sports Sciences, Tokyo, Japan
| |
Collapse
|
21
|
Moll K, Gussew A, Hein C, Stutzig N, Reichenbach JR. Combined spiroergometry and 31 P-MRS of human calf muscle during high-intensity exercise. NMR IN BIOMEDICINE 2017; 30:e3723. [PMID: 28340292 DOI: 10.1002/nbm.3723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 02/07/2017] [Accepted: 02/08/2017] [Indexed: 06/06/2023]
Abstract
Simultaneous measurements of pulmonary oxygen consumption (VO2 ), carbon dioxide exhalation (VCO2 ) and phosphorus magnetic resonance spectroscopy (31 P-MRS) are valuable in physiological studies to evaluate muscle metabolism during specific loads. Therefore, the aim of this study was to adapt a commercially available spirometric device to enable measurements of VO2 and VCO2 whilst simultaneously performing 31 P-MRS at 3 T. Volunteers performed intense plantar flexion of their right calf muscle inside the MR scanner against a pneumatic MR-compatible pedal ergometer. The use of a non-magnetic pneumotachograph and extension of the sampling line from 3 m to 5 m to place the spirometric device outside the MR scanner room did not affect adversely the measurements of VO2 and VCO2 . Response and delay times increased, on average, by at most 0.05 s and 0.79 s, respectively. Overall, we were able to demonstrate a feasible ventilation response (VO2 = 1.05 ± 0.31 L/min; VCO2 = 1.11 ± 0.33 L/min) during the exercise of a single calf muscle, as well as a good correlation between local energy metabolism and muscular acidification (τPCr fast and pH; R2 = 0.73, p < 0.005) and global respiration (τPCr fast and VO2 ; R2 = 0.55, p = 0.01). This provides improved insights into aerobic and anaerobic energy supply during strong muscular performances.
Collapse
Affiliation(s)
- K Moll
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - A Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
| | - C Hein
- Ganshorn Medizin Electronic GmbH, Niederlauer, Germany
| | - N Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Stuttgart, Germany
| | - J R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, Jena University Hospital, Friedrich Schiller University Jena, Jena, Germany
- Michael Stifel Center for Data-Driven and Simulation Science Jena, Friedrich Schiller University Jena, Jena, Germany
| |
Collapse
|
22
|
Barclay CJ. Energy demand and supply in human skeletal muscle. J Muscle Res Cell Motil 2017; 38:143-155. [PMID: 28286928 DOI: 10.1007/s10974-017-9467-7] [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: 11/05/2016] [Accepted: 02/14/2017] [Indexed: 12/18/2022]
Abstract
The energy required for muscle contraction is provided by the breakdown of ATP but the amount of ATP in muscles cells is sufficient to power only a short duration of contraction. Buffering of ATP by phosphocreatine, a reaction catalysed by creatine kinase, extends the duration of activity possible but sustained activity depends on continual regeneration of PCr. This is achieved using ATP generated by oxidative processes and, during intense activity, by anaerobic glycolysis. The rate of ATP breakdown ranges from 70 to 140 mM min-1 during isometric contractions of various intensity to as much as 400 mM min-1 during intense, dynamic activity. The maximum rate of oxidative energy supply in untrained people is ~50 mM min-1 which, if the contraction duty cycle is 0.5 as is often the case in cyclic activity, is sufficient to match an ATP breakdown rate during contraction of 100 mM min-1. During brief, intense activity the rate of ATP turnover can exceed the rates of PCr regeneration by combined oxidative and glycolytic energy supply, resulting in a net decrease in PCr concentration. Glycolysis has the capacity to produce between 30 and 50 mM of ATP so that, for example, anaerobic glycolysis could provide ATP at an average of 100 mM min-1 over 30 s of exhausting activity. The creatine kinase reaction plays an important role not only in buffering ATP but also in communicating energy demand from sites of ATP breakdown to the mitochondria. In that role, creatine kinases acts to slow and attenuate the response of mitochondria to changes in energy demand.
Collapse
Affiliation(s)
- C J Barclay
- School of Allied Health Sciences, Griffith University, Gold Coast, QLD, 4222, Australia.
| |
Collapse
|
23
|
Abstract
This minireview focuses on selected, noninvasive imaging techniques that have been used in the study of exercise physiology. These imaging modalities can be roughly divided into two categories: tracer based and nontracer based. Tracer-based methods use radiolabeled substrates whose location and quantity can subsequently be imaged once they are incorporated into metabolic processes. Nontracer-based imaging modalities rely on specific properties of substrates to identify metabolites and determine their concentrations. Identification and quantification of metabolites is usually based on magnetic properties or on differences in light absorption. In this review, we will highlight two tracer-based imaging modalities, positron emission tomography and single-photon-emission computed tomography, as well as two nontracer-based methods, magnetic resonance spectroscopy and near-infrared spectroscopy. Some of the recent findings that each technique has provided on cerebral and skeletal muscle metabolism during exercise, as well as the strengths and limitations of each technique, will be discussed.
Collapse
Affiliation(s)
- Thorsten Rudroff
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - Nathaniel B Ketelhut
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| | - John H Kindred
- Integrative Neurophysiology Laboratory, Department of Health and Exercise Science, Colorado State University , Fort Collins, Colorado
| |
Collapse
|
24
|
Black MI, Jones AM, Blackwell JR, Bailey SJ, Wylie LJ, McDonagh STJ, Thompson C, Kelly J, Sumners P, Mileva KN, Bowtell JL, Vanhatalo A. Muscle metabolic and neuromuscular determinants of fatigue during cycling in different exercise intensity domains. J Appl Physiol (1985) 2016; 122:446-459. [PMID: 28008101 PMCID: PMC5429469 DOI: 10.1152/japplphysiol.00942.2016] [Citation(s) in RCA: 158] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 12/12/2016] [Accepted: 12/16/2016] [Indexed: 01/15/2023] Open
Abstract
The gas exchange threshold and the critical power demarcate discrete exercise intensity domains. For the first time, we show that the limit of tolerance during whole body exercise within these domains is characterized by distinct metabolic and neuromuscular responses. Fatigue development during exercise greater than critical power is associated with the attainment of consistent “limiting” values of muscle metabolites, whereas substrate availability and limitations to muscle activation may constrain performance at lower intensities. Lactate or gas exchange threshold (GET) and critical power (CP) are closely associated with human exercise performance. We tested the hypothesis that the limit of tolerance (Tlim) during cycle exercise performed within the exercise intensity domains demarcated by GET and CP is linked to discrete muscle metabolic and neuromuscular responses. Eleven men performed a ramp incremental exercise test, 4–5 severe-intensity (SEV; >CP) constant-work-rate (CWR) tests until Tlim, a heavy-intensity (HVY; <CP but >GET) CWR test until Tlim, and a moderate-intensity (MOD; <GET) CWR test until Tlim. Muscle biopsies revealed that a similar (P > 0.05) muscle metabolic milieu (i.e., low pH and [PCr] and high [lactate]) was attained at Tlim (approximately 2–14 min) for all SEV exercise bouts. The muscle metabolic perturbation was greater at Tlim following SEV compared with HVY, and also following SEV and HVY compared with MOD (all P < 0.05). The normalized M-wave amplitude for the vastus lateralis (VL) muscle decreased to a similar extent following SEV (−38 ± 15%), HVY (−68 ± 24%), and MOD (−53 ± 29%), (P > 0.05). Neural drive to the VL increased during SEV (4 ± 4%; P < 0.05) but did not change during HVY or MOD (P > 0.05). During SEV and HVY, but not MOD, the rates of change in M-wave amplitude and neural drive were correlated with changes in muscle metabolic ([PCr], [lactate]) and blood ionic/acid-base status ([lactate], [K+]) (P < 0.05). The results of this study indicate that the metabolic and neuromuscular determinants of fatigue development differ according to the intensity domain in which the exercise is performed. NEW & NOTEWORTHY The gas exchange threshold and the critical power demarcate discrete exercise intensity domains. For the first time, we show that the limit of tolerance during whole-body exercise within these domains is characterized by distinct metabolic and neuromuscular responses. Fatigue development during exercise greater than critical power is associated with the attainment of consistent “limiting” values of muscle metabolites, whereas substrate availability and limitations to muscle activation may constrain performance at lower intensities.
Collapse
Affiliation(s)
- Matthew I Black
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom; and
| | - Andrew M Jones
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Jamie R Blackwell
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Stephen J Bailey
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom.,School of Sport, Exercise and Health Sciences, Loughborough University, United Kingdom; and
| | - Lee J Wylie
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Sinead T J McDonagh
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Christopher Thompson
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - James Kelly
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Paul Sumners
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Katya N Mileva
- Sport and Exercise Science Research Centre, School of Applied Sciences, London South Bank University, London, United Kingdom
| | - Joanna L Bowtell
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom
| | - Anni Vanhatalo
- College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom;
| |
Collapse
|
25
|
Pallarés JG, Morán-Navarro R, Ortega JF, Fernández-Elías VE, Mora-Rodriguez R. Validity and Reliability of Ventilatory and Blood Lactate Thresholds in Well-Trained Cyclists. PLoS One 2016; 11:e0163389. [PMID: 27657502 PMCID: PMC5033582 DOI: 10.1371/journal.pone.0163389] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 09/06/2016] [Indexed: 11/18/2022] Open
Abstract
PURPOSE The purpose of this study was to determine, i) the reliability of blood lactate and ventilatory-based thresholds, ii) the lactate threshold that corresponds with each ventilatory threshold (VT1 and VT2) and with maximal lactate steady state test (MLSS) as a proxy of cycling performance. METHODS Fourteen aerobically-trained male cyclists ([Formula: see text] 62.1±4.6 ml·kg-1·min-1) performed two graded exercise tests (50 W warm-up followed by 25 W·min-1) to exhaustion. Blood lactate, [Formula: see text] and [Formula: see text] data were collected at every stage. Workloads at VT1 (rise in [Formula: see text];) and VT2 (rise in [Formula: see text]) were compared with workloads at lactate thresholds. Several continuous tests were needed to detect the MLSS workload. Agreement and differences among tests were assessed with ANOVA, ICC and Bland-Altman. Reliability of each test was evaluated using ICC, CV and Bland-Altman plots. RESULTS Workloads at lactate threshold (LT) and LT+2.0 mMol·L-1 matched the ones for VT1 and VT2, respectively (p = 0.147 and 0.539; r = 0.72 and 0.80; Bias = -13.6 and 2.8, respectively). Furthermore, workload at LT+0.5 mMol·L-1 coincided with MLSS workload (p = 0.449; r = 0.78; Bias = -4.5). Lactate threshold tests had high reliability (CV = 3.4-3.7%; r = 0.85-0.89; Bias = -2.1-3.0) except for DMAX method (CV = 10.3%; r = 0.57; Bias = 15.4). Ventilatory thresholds show high reliability (CV = 1.6%-3.5%; r = 0.90-0.96; Bias = -1.8-2.9) except for RER = 1 and V-Slope (CV = 5.0-6.4%; r = 0.79; Bias = -5.6-12.4). CONCLUSIONS Lactate threshold tests can be a valid and reliable alternative to ventilatory thresholds to identify the workloads at the transition from aerobic to anaerobic metabolism.
Collapse
Affiliation(s)
- Jesús G. Pallarés
- University of Castilla-La Mancha, Exercise Physiology Laboratory at Toledo, Toledo, Spain
- Human Performance and Sports Science Laboratory, Faculty of Sport Sciences, University of Murcia, Murcia, Spain
| | - Ricardo Morán-Navarro
- University of Castilla-La Mancha, Exercise Physiology Laboratory at Toledo, Toledo, Spain
- Human Performance and Sports Science Laboratory, Faculty of Sport Sciences, University of Murcia, Murcia, Spain
| | - Juan Fernando Ortega
- University of Castilla-La Mancha, Exercise Physiology Laboratory at Toledo, Toledo, Spain
| | | | - Ricardo Mora-Rodriguez
- University of Castilla-La Mancha, Exercise Physiology Laboratory at Toledo, Toledo, Spain
- * E-mail:
| |
Collapse
|
26
|
Rzanny R, Stutzig N, Hiepe P, Gussew A, Thorhauer HA, Reichenbach JR. The reproducibility of different metabolic markers for muscle fiber type distributions investigated by functional 31P-MRS during dynamic exercise. Z Med Phys 2016; 26:323-338. [PMID: 27527556 DOI: 10.1016/j.zemedi.2016.06.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 06/20/2016] [Accepted: 06/23/2016] [Indexed: 02/06/2023]
Abstract
PURPOSE The objective of the study was to investigate the reproducibility of exercise induced pH-heterogeneity by splitting of the inorganic phosphate (Pi) signal in the corresponding 31P-MRS spectra and to compare results of this approach with other fiber-type related markers, like phosphocreatine/adenosine triphosphate (PCr/ATP) ratio, and PCr-recovery parameters. MATERIAL AND METHODS Subjects (N=3) with different sportive background were tested in 10 test sessions separated by at least 3 days. A MR-compatible pedal ergometer was used to perform the exercise and to induce a pH-based splitting of the Pi-signal in 31P-MR spectra of the medial gastrocnemius muscle. The PCr recovery was analyzed using a non-negative least square algorithm (NNLS) and multi-exponential regression analysis to estimate the number of non-exponential components as well as their amplitude and time constant. The reproducibility of the estimated metabolic marker and the resulting fiber-type distributions between the 10 test sessions were compared. RESULTS The reproducibility (standard deviation between measurements) based on (1) Pi components varied from 2% to 4%, (2) PCr recovery time components varied from 10% to 12% and (3) phosphate concentrations at rest varied from 8% to 11% between test sessions. Due to the sportive activity differences between the 3 subjects were expected in view of fiber type distribution. All estimated markers indicate the highest type I percentage for volunteer 3 medium for volunteer 2 and the lowest for volunteer 1. CONCLUSIONS The relative high reproducibility of pH dependent Pi components during exercise indicates a high potential of this method to estimate muscle fiber-type distributions in vivo. To make this method usable not only to detect differences in muscle fiber distributions but also to determine individual fiber-type volume contents it is therefore recommended to validate this marker by histological methods and to reveal the effects of muscle fiber recruitments and fiber-type specific Pi concentrations on the intensity ratios between the splitted Pi-components.
Collapse
Affiliation(s)
- Reinhard Rzanny
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany.
| | - Norman Stutzig
- Exercise Science, Institute of Sport and Movement Science, University of Stuttgart, Germany
| | - Patrick Hiepe
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
| | - Alexander Gussew
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
| | | | - Jürgen R Reichenbach
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology, University Hospital Jena, Germany
| |
Collapse
|
27
|
Regional Differences in Muscle Energy Metabolism in Human Muscle by 31P-Chemical Shift Imaging. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016. [PMID: 26782194 DOI: 10.1007/978-1-4939-3023-4_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Previous studies have reported significant region-dependent differences in the fiber-type composition of human skeletal muscle. It is therefore hypothesized that there is a difference between the deep and superficial parts of muscle energy metabolism during exercise. We hypothesized that the inorganic phosphate (Pi)/phosphocreatine (PCr) ratio of the superficial parts would be higher, compared with the deep parts, as the work rate increases, because the muscle fiber-type composition of the fast-type may be greater in the superficial parts compared with the deep parts. This study used two-dimensional 31Phosphorus Chemical Shift Imaging (31P-CSI) to detect differences between the deep and superficial parts of the human leg muscles during dynamic knee extension exercise. Six healthy men participated in this study (age 27±1 year, height 169.4±4.1 cm, weight 65.9±8.4 kg). The experiments were carried out with a 1.5-T superconducting magnet with a 5-in. diameter circular surface coil. The subjects performed dynamic one-legged knee extension exercise in the prone position, with the transmit-receive coil placed under the right quadriceps muscles in the magnet. The subjects pulled down an elastic rubber band attached to the ankle at a frequency of 0.25, 0.5 and 1 Hz for 320 s each. The intracellular pH (pHi) was calculated from the median chemical shift of the Pi peak relative to PCr. No significant difference in Pi/PCr was observed between the deep and the superficial parts of the quadriceps muscles at rest. The Pi/PCr of the superficial parts was not significantly increased with increasing work rate. Compared with the superficial areas, the Pi/PCr of the deep parts was significantly higher (p<0.05) at 1 Hz. The pHi showed no significant difference between the two parts. These results suggest that muscle oxidative metabolism is different between deep and superficial parts of quadriceps muscles during dynamic exercise.
Collapse
|
28
|
Regional Differences of Metabolic Response During Dynamic Incremental Exercise by 31P-CSI. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 923:269-274. [DOI: 10.1007/978-3-319-38810-6_36] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
29
|
Ferguson C, Cannon DT, Wylde LA, Benson AP, Rossiter HB. Power-Velocity and Power-Efficiency Implications in the Limitation of Ramp Incremental Cycle Ergometry: Reply to Morales-Alamo et al. J Appl Physiol (1985) 2015; 120:477. [PMID: 26702026 DOI: 10.1152/japplphysiol.01067.2015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Carrie Ferguson
- School of Biomedical Sciences & Multidisciplinary Cardiovascular Research Centre, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom;
| | - Daniel T Cannon
- School of Exercise & Nutritional Sciences, San Diego State University, San Diego, California; and
| | - Lindsey A Wylde
- School of Biomedical Sciences & Multidisciplinary Cardiovascular Research Centre, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Alan P Benson
- School of Biomedical Sciences & Multidisciplinary Cardiovascular Research Centre, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
| | - Harry B Rossiter
- School of Biomedical Sciences & Multidisciplinary Cardiovascular Research Centre, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom; Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| |
Collapse
|
30
|
Okushima D, Poole DC, Rossiter HB, Barstow TJ, Kondo N, Ohmae E, Koga S. Muscle deoxygenation in the quadriceps during ramp incremental cycling: Deep vs. superficial heterogeneity. J Appl Physiol (1985) 2015; 119:1313-9. [PMID: 26404619 DOI: 10.1152/japplphysiol.00574.2015] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Accepted: 09/21/2015] [Indexed: 01/31/2023] Open
Abstract
Muscle deoxygenation (i.e., deoxy[Hb + Mb]) during exercise assesses the matching of oxygen delivery (Q̇O2) to oxygen utilization (V̇O2). Until now limitations in near-infrared spectroscopy (NIRS) technology did not permit discrimination of deoxy[Hb + Mb] between superficial and deep muscles. In humans, the deep quadriceps is more highly vascularized and oxidative than the superficial quadriceps. Using high-power time-resolved NIRS, we tested the hypothesis that deoxygenation of the deep quadriceps would be less than in superficial muscle during incremental cycling exercise in eight males. Pulmonary V̇O2 was measured and muscle deoxy[Hb + Mb] was determined in the superficial vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF-s) and the deep rectus femoris (RF-d). deoxy[Hb + Mb] in RF-d was significantly less than VL at 70% (67.2 ± 7.0 vs. 75.5 ± 10.7 μM) and 80% (71.4 ± 11.0 vs. 79.0 ± 15.4 μM) of peak work rate (WR(peak)), but greater than VL and VM at WR(peak) (87.7 ± 32.5 vs. 76.6 ± 17.5 and 75.1 ± 19.9 μM). RF-s was intermediate at WR(peak) (82.6 ± 18.7 μM). Total hemoglobin and myoglobin concentration and tissue oxygen saturation were significantly greater in RF-d than RF-s throughout exercise. The slope of deoxy[Hb + Mb] increase (proportional to Q̇O2/V̇O2) in VL and VM slowed markedly above 70% WR(peak), whereas it became greater in RF-d. This divergent deoxygenation pattern may be due to a greater population of slow-twitch muscle fibers in the RF-d muscle and the differential recruitment profiles and vascular and metabolic control properties of specific fiber populations within superficial and deeper muscle regions.
Collapse
Affiliation(s)
- Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan
| | - David C Poole
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-University of California Los Angeles Medical Center, Torrance, California
| | - Thomas J Barstow
- Departments of Kinesiology and Anatomy and Physiology, Kansas State University, Manhattan, Kansas
| | | | | | - Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Hyogo, Japan;
| |
Collapse
|
31
|
Torres-Peralta R, Losa-Reyna J, González-Izal M, Perez-Suarez I, Calle-Herrero J, Izquierdo M, Calbet JAL. Muscle activation during exercise in severe acute hypoxia: role of absolute and relative intensity. High Alt Med Biol 2015; 15:472-82. [PMID: 25225839 DOI: 10.1089/ham.2014.1027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The aim of this study was to determine the influence of severe acute hypoxia on muscle activation during whole body dynamic exercise. Eleven young men performed four incremental cycle ergometer tests to exhaustion breathing normoxic (FIO2=0.21, two tests) or hypoxic gas (FIO2=0.108, two tests). Surface electromyography (EMG) activities of rectus femoris (RF), vastus medialis (VL), vastus lateralis (VL), and biceps femoris (BF) were recorded. The two normoxic and the two hypoxic tests were averaged to reduce EMG variability. Peak VO2 was 34% lower in hypoxia than in normoxia (p<0.05). The EMG root mean square (RMS) increased with exercise intensity in all muscles (p<0.05), with greater effect in hypoxia than in normoxia in the RF and VM (p<0.05), and a similar trend in VL (p=0.10). At the same relative intensity, the RMS was greater in normoxia than in hypoxia in RF, VL, and BF (p<0.05), with a similar trend in VM (p=0.08). Median frequency increased with exercise intensity (p<0.05), and was higher in hypoxia than in normoxia in VL (p<0.05). Muscle contraction burst duration increased with exercise intensity in VM and VL (p<0.05), without clear effects of FIO2. No significant FIO2 effects on frequency domain indices were observed when compared at the same relative intensity. In conclusion, muscle activation during whole body exercise increases almost linearly with exercise intensity, following a muscle-specific pattern, which is adjusted depending on the FIO2 and the relative intensity of exercise. Both VL and VM are increasingly involved in power output generation with the increase of intensity and the reduction in FIO2.
Collapse
Affiliation(s)
- Rafael Torres-Peralta
- 1 Department of Physical Education, University of Las Palmas de Gran Canaria , Campus Universitario de Tafira s/n, Las Palmas de Gran Canaria, Spain
| | | | | | | | | | | | | |
Collapse
|
32
|
JUBEAU MARC, LE FUR YANN, DUHAMEL GUILLAUME, WEGRZYK JENNIFER, CONFORT-GOUNY SYLVIANE, VILMEN CHRISTOPHE, COZZONE PATRICKJ, MATTEI JEANPIERRE, BENDAHAN DAVID, GONDIN JULIEN. Localized Metabolic and T2 Changes Induced by Voluntary and Evoked Contractions. Med Sci Sports Exerc 2015; 47:921-30. [DOI: 10.1249/mss.0000000000000491] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
33
|
Koga S, Barstow TJ, Okushima D, Rossiter HB, Kondo N, Ohmae E, Poole DC. Validation of a high-power, time-resolved, near-infrared spectroscopy system for measurement of superficial and deep muscle deoxygenation during exercise. J Appl Physiol (1985) 2015; 118:1435-42. [PMID: 25840439 DOI: 10.1152/japplphysiol.01003.2014] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 03/31/2015] [Indexed: 11/22/2022] Open
Abstract
Near-infrared assessment of skeletal muscle is restricted to superficial tissues due to power limitations of spectroscopic systems. We reasoned that understanding of muscle deoxygenation may be improved by simultaneously interrogating deeper tissues. To achieve this, we modified a high-power (∼8 mW), time-resolved, near-infrared spectroscopy system to increase depth penetration. Precision was first validated using a homogenous optical phantom over a range of inter-optode spacings (OS). Coefficients of variation from 10 measurements were minimal (0.5-1.9%) for absorption (μa), reduced scattering, simulated total hemoglobin, and simulated O2 saturation. Second, a dual-layer phantom was constructed to assess depth sensitivity, and the thickness of the superficial layer was varied. With a superficial layer thickness of 1, 2, 3, and 4 cm (μa = 0.149 cm(-1)), the proportional contribution of the deep layer (μa = 0.250 cm(-1)) to total μa was 80.1, 26.9, 3.7, and 0.0%, respectively (at 6-cm OS), validating penetration to ∼3 cm. Implementation of an additional superficial phantom to simulate adipose tissue further reduced depth sensitivity. Finally, superficial and deep muscle spectroscopy was performed in six participants during heavy-intensity cycle exercise. Compared with the superficial rectus femoris, peak deoxygenation of the deep rectus femoris (including the superficial intermedius in some) was not significantly different (deoxyhemoglobin and deoxymyoglobin concentration: 81.3 ± 20.8 vs. 78.3 ± 13.6 μM, P > 0.05), but deoxygenation kinetics were significantly slower (mean response time: 37 ± 10 vs. 65 ± 9 s, P ≤ 0.05). These data validate a high-power, time-resolved, near-infrared spectroscopy system with large OS for measuring the deoxygenation of deep tissues and reveal temporal and spatial disparities in muscle deoxygenation responses to exercise.
Collapse
Affiliation(s)
- Shunsaku Koga
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan;
| | - Thomas J Barstow
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| | - Dai Okushima
- Applied Physiology Laboratory, Kobe Design University, Kobe, Japan
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California
| | | | | | - David C Poole
- Departments of Anatomy and Physiology and Kinesiology, Kansas State University, Manhattan, Kansas
| |
Collapse
|
34
|
Abstract
Evidence is presented that the rate and equilibrium constants in mitochondrial oxidative phosphorylation set and maintain metabolic homeostasis in eukaryotic cells. These internal constants determine the energy state ([ATP]/[ADP][Pi]), and the energy state maintains homeostasis through a bidirectional sensory/signaling control network that reaches every aspect of cellular metabolism. The energy state is maintained with high precision (to ∼1 part in 10(10)), and the control system can respond to transient changes in energy demand (ATP utilization) of more than 100 times the resting rate. Epigenetic and environmental factors are able to "fine-tune" the programmed set point over a narrow range to meet the special needs associated with cell differentiation and chronic changes in metabolic requirements. The result is robust across-platform control of metabolism, which is essential to cellular differentiation and the evolution of complex organisms. A model of oxidative phosphorylation is presented, for which the steady-state rate expression has been derived and computer programmed. The behavior of oxidative phosphorylation predicted by the model is shown to fit the experimental data available for isolated mitochondria as well as for cells and tissues. This includes measurements from several different mammalian tissues as well as from insect flight muscle and plants. The respiratory chain and oxidative phosphorylation is remarkably similar for all higher plants and animals. This is consistent with the efficient synthesis of ATP and precise control of metabolic homeostasis provided by oxidative phosphorylation being a key to cellular differentiation and the evolution of structures with specialized function.
Collapse
Affiliation(s)
- David F Wilson
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
35
|
Kemp GJ, Ahmad RE, Nicolay K, Prompers JJ. Quantification of skeletal muscle mitochondrial function by 31P magnetic resonance spectroscopy techniques: a quantitative review. Acta Physiol (Oxf) 2015; 213:107-44. [PMID: 24773619 DOI: 10.1111/apha.12307] [Citation(s) in RCA: 102] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 12/30/2013] [Accepted: 04/23/2014] [Indexed: 12/16/2022]
Abstract
Magnetic resonance spectroscopy (MRS) can give information about cellular metabolism in vivo which is difficult to obtain in other ways. In skeletal muscle, non-invasive (31) P MRS measurements of the post-exercise recovery kinetics of pH, [PCr], [Pi] and [ADP] contain valuable information about muscle mitochondrial function and cellular pH homeostasis in vivo, but quantitative interpretation depends on understanding the underlying physiology. Here, by giving examples of the analysis of (31) P MRS recovery data, by some simple computational simulation, and by extensively comparing data from published studies using both (31) P MRS and invasive direct measurements of muscle O2 consumption in a common analytical framework, we consider what can be learnt quantitatively about mitochondrial metabolism in skeletal muscle using MRS-based methodology. We explore some technical and conceptual limitations of current methods, and point out some aspects of the physiology which are still incompletely understood.
Collapse
Affiliation(s)
- G. J. Kemp
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - R. E. Ahmad
- Department of Musculoskeletal Biology, and Magnetic Resonance and Image Analysis Research Centre; University of Liverpool; Liverpool UK
| | - K. Nicolay
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
| | - J. J. Prompers
- Biomedical NMR; Department of Biomedical Engineering; Eindhoven University of Technology; Eindhoven the Netherlands
| |
Collapse
|
36
|
West MA, Loughney L, Lythgoe D, Barben CP, Adams VL, Bimson WE, Grocott MPW, Jack S, Kemp GJ. The effect of neoadjuvant chemoradiotherapy on whole-body physical fitness and skeletal muscle mitochondrial oxidative phosphorylation in vivo in locally advanced rectal cancer patients--an observational pilot study. PLoS One 2014; 9:e111526. [PMID: 25478898 PMCID: PMC4257525 DOI: 10.1371/journal.pone.0111526] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 09/26/2014] [Indexed: 11/18/2022] Open
Abstract
Background In the United Kingdom, patients with locally advanced rectal cancer routinely receive neoadjuvant chemoradiotherapy. However, the effects of this on physical fitness are unclear. This pilot study is aimed to investigate the effect of neoadjuvant chemoradiotherapy on objectively measured in vivo muscle mitochondrial function and whole-body physical fitness. Methods We prospectively studied 12 patients with rectal cancer who completed standardized neoadjuvant chemoradiotherapy, recruited from a large tertiary cancer centre, between October 2012 and July 2013. All patients underwent a cardiopulmonary exercise test and a phosphorus magnetic resonance spectroscopy quadriceps muscle exercise-recovery study before and after neoadjuvant chemoradiotherapy. Data were analysed and reported blind to patient identity and clinical course. Primary variables of interest were the two physical fitness measures; oxygen uptake at estimated anaerobic threshold and oxygen uptake at Peak exercise (ml.kg−1.min−1), and the post-exercise phosphocreatine recovery rate constant (min−1), a measure of muscle mitochondrial capacity in vivo. Results Median age was 67 years (IQR 64–75). Differences (95%CI) in all three primary variables were significantly negative post-NACRT: Oxygen uptake at estimated anaerobic threshold −2.4 ml.kg−1.min−1 (−3.8, −0.9), p = 0.004; Oxygen uptake at Peak −4.0 ml.kg−1.min−1 (−6.8, −1.1), p = 0.011; and post-exercise phosphocreatine recovery rate constant −0.34 min−1 (−0.51, −0.17), p<0.001. Conclusion The significant decrease in both whole-body physical fitness and in vivo muscle mitochondrial function raises the possibility that muscle mitochondrial mechanisms, no doubt multifactorial, may be important in deterioration of physical fitness following neoadjuvant chemoradiotherapy. This may have implications for targeted interventions to improve physical fitness pre-surgery. Trial Registration Clinicaltrials.gov registration NCT01859442
Collapse
Affiliation(s)
- Malcolm A. West
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | - Lisa Loughney
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
| | - Daniel Lythgoe
- Cancer Research UK Liverpool Cancer Trials Unit, University of Liverpool, Liverpool, United Kingdom
| | - Christopher P. Barben
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
| | - Valerie L. Adams
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
| | - William E. Bimson
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
| | - Michael P. W. Grocott
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Sandy Jack
- Colorectal Surgery Research Group, Aintree University Hospitals NHS Foundation Trust, Liverpool, United Kingdom
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Critical Care Research Area, Southampton NIHR Respiratory Biomedical Research Unit, Southampton, United Kingdom
- Anaesthesia and Critical Care Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom
- Integrative Physiology and Critical Illness Group, Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Graham J. Kemp
- Department of Musculoskeletal Biology and MRC – Arthritis Research UK Centre for Integrated Research into Musculoskeletal Ageing (CIMA), Faculty of Health and Life Sciences, University of Liverpool, Liverpool, United Kingdom
- Magnetic Resonance and Image Analysis Research Centre (MARIARC), University of Liverpool, Liverpool, United Kingdom
| |
Collapse
|
37
|
Cannon DT, Bimson WE, Hampson SA, Bowen TS, Murgatroyd SR, Marwood S, Kemp GJ, Rossiter HB. Skeletal muscle ATP turnover by 31P magnetic resonance spectroscopy during moderate and heavy bilateral knee extension. J Physiol 2014; 592:5287-300. [PMID: 25281731 DOI: 10.1113/jphysiol.2014.279174] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
During constant-power high-intensity exercise, the expected increase in oxygen uptake (V̇O2) is supplemented by a V̇O2 slow component (V̇O2 sc ), reflecting reduced work efficiency, predominantly within the locomotor muscles. The intracellular source of inefficiency is postulated to be an increase in the ATP cost of power production (an increase in P/W). To test this hypothesis, we measured intramuscular ATP turnover with (31)P magnetic resonance spectroscopy (MRS) and whole-body V̇O2 during moderate (MOD) and heavy (HVY) bilateral knee-extension exercise in healthy participants (n = 14). Unlocalized (31)P spectra were collected from the quadriceps throughout using a dual-tuned ((1)H and (31)P) surface coil with a simple pulse-and-acquire sequence. Total ATP turnover rate (ATPtot) was estimated at exercise cessation from direct measurements of the dynamics of phosphocreatine (PCr) and proton handling. Between 3 and 8 min during MOD, there was no discernable V̇O2 sc (mean ± SD, 0.06 ± 0.12 l min(-1)) or change in [PCr] (30 ± 8 vs. 32 ± 7 mm) or ATPtot (24 ± 14 vs. 17 ± 14 mm min(-1); each P = n.s.). During HVY, the V̇O2 sc was 0.37 ± 0.16 l min(-1) (22 ± 8%), [PCr] decreased (19 ± 7 vs. 18 ± 7 mm, or 12 ± 15%; P < 0.05) and ATPtot increased (38 ± 16 vs. 44 ± 14 mm min(-1), or 26 ± 30%; P < 0.05) between 3 and 8 min. However, the increase in ATPtot (ΔATPtot) was not correlated with the V̇O2 sc during HVY (r(2) = 0.06; P = n.s.). This lack of relationship between ΔATPtot and V̇O2 sc , together with a steepening of the [PCr]-V̇O2 relationship in HVY, suggests that reduced work efficiency during heavy exercise arises from both contractile (P/W) and mitochondrial sources (the O2 cost of ATP resynthesis; P/O).
Collapse
Affiliation(s)
- Daniel T Cannon
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - William E Bimson
- Magnetic Resonance & Image Analysis Research Centre, University of Liverpool, Liverpool, UK
| | - Sophie A Hampson
- School of Health Sciences, Liverpool Hope University, Liverpool, UK
| | - T Scott Bowen
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK Department of Internal Medicine and Cardiology, University of Leipzig - Heart Center, Leipzig, DE
| | - Scott R Murgatroyd
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Simon Marwood
- School of Health Sciences, Liverpool Hope University, Liverpool, UK
| | - Graham J Kemp
- Magnetic Resonance & Image Analysis Research Centre, University of Liverpool, Liverpool, UK Department of Musculoskeletal Biology, University of Liverpool, Liverpool, UK
| | - Harry B Rossiter
- Rehabilitation Clinical Trials Center, Division of Respiratory & Critical Care Physiology & Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| |
Collapse
|
38
|
Spencer MD, Amano T, Kondo N, Kowalchuk JM, Koga S. Muscle O2 extraction reserve during intense cycling is site-specific. J Appl Physiol (1985) 2014; 117:1199-206. [PMID: 25257877 DOI: 10.1152/japplphysiol.00060.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study compared peak muscle deoxygenation ([HHb]peak) responses at three quadriceps sites during occlusion (OCC), ramp incremental (RI), severe- (SVR) and moderate-intensity (MOD) exercise. Seven healthy men (25 ± 4 yr) each completed a stationary cycling RI (20 W/min) test to determine [HHb]peak [at distal and proximal vastus lateralis (VLD and VLP) and rectus femoris (RF)], peak V̇O2 (V̇O(2peak)), gas exchange threshold (GET), and peak work rate (WR(peak)). Subjects also completed MOD (WR = 80% GET) and SVR exercise (WR corresponding to 120% V̇O(2peak)) with absolute [HHb] (quantified by multichannel, time-resolved near-infrared spectroscopy) and pulmonary VO2 (V̇O(2p)) monitored continuously. Additionally, [HHb] and total hemoglobin ([Hb]tot) were monitored at rest and during subsequent OCC (250 mmHg). Site-specific adipose tissue thickness was assessed (B-mode ultrasound), and its relationship with resting [Hb]tot was used to correct absolute [HHb]. For VLD and RF, [HHb]peak was higher (P < 0.05) during OCC (VLD = 111 ± 38, RF = 114 ± 26 μM) than RI (VLD 64 ± 14, RF = 85 ± 20) and SVR (VLD = 63 ± 13, RF = 81 ± 18). [HHb]peak was similar (P > 0.05) across these conditions at the VLP (OCC = 67 ± 17, RI = 69 ± 17, SVR = 63 ± 17 μM). [HHb] peaked and then decreased prior to exercise cessation during SVR at all three muscle sites. [HHb]peak during MOD was consistently lower than other conditions at all sites. A "[HHb] reserve" exists during intense cycling at the VLD and RF, likely implying either sufficient blood flow to meet oxidative demands or insufficient diffusion time for complete equilibration. In VLP this [HHb] reserve was absent, suggesting that a critical PO2 may be challenged during intense cycling.
Collapse
Affiliation(s)
- Matthew D Spencer
- Kobe Design University, Kobe, Hyogo, Japan; The University of Western Ontario, London, Ontario, Canada; and
| | | | | | | | | |
Collapse
|
39
|
Hiepe P, Gussew A, Rzanny R, Anders C, Walther M, Scholle HC, Reichenbach JR. Interrelations of muscle functional MRI, diffusion-weighted MRI and (31) P-MRS in exercised lower back muscles. NMR IN BIOMEDICINE 2014; 27:958-970. [PMID: 24953438 DOI: 10.1002/nbm.3141] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2014] [Revised: 04/17/2014] [Accepted: 04/29/2014] [Indexed: 06/03/2023]
Abstract
Exercise-induced changes of transverse proton relaxation time (T2 ), tissue perfusion and metabolic turnover were investigated in the lower back muscles of volunteers by applying muscle functional MRI (mfMRI) and diffusion-weighted imaging (DWI) before and after as well as dynamic (31) P-MRS during the exercise. Inner (M. multifidus, MF) and outer lower back muscles (M. erector spinae, ES) were examined in 14 healthy young men performing a sustained isometric trunk-extension. Significant phosphocreatine (PCr) depletions ranging from 30% (ES) to 34% (MF) and Pi accumulations between 95% (left ES) and 120%-140% (MF muscles and right ES) were observed during the exercise, which were accompanied by significantly decreased pH values in all muscles (∆pH ≈ -0.05). Baseline T2 values were similar across all investigated muscles (approximately 27 ms at 3 T), but revealed right-left asymmetric increases (T2 ,inc ) after the exercise (right ES/MF: T2 ,inc = 11.8/9.7%; left ES/MF: T2 ,inc = 4.6/8.9%). Analyzed muscles also showed load-induced increases in molecular diffusion D (p = .007) and perfusion fraction f (p = .002). The latter parameter was significantly higher in the MF than in the ES muscles both at rest and post exercise. Changes in PCr (p = .03), diffusion (p < .01) and perfusion (p = .03) were strongly associated with T2,inc , and linear mixed model analysis revealed that changes in PCr and perfusion both affect T2,inc (p < .001). These findings support previous assumptions that T2 changes are not only an intra-cellular phenomenon resulting from metabolic stress but are also affected by increased perfusion in loaded muscles.
Collapse
Affiliation(s)
- Patrick Hiepe
- Medical Physics Group, Institute of Diagnostic and Interventional Radiology I, Center of Radiology, Jena University Hospital - Friedrich Schiller University, Jena, Germany
| | | | | | | | | | | | | |
Collapse
|
40
|
Southern WM, Ryan TE, Reynolds MA, McCully K. Reproducibility of near-infrared spectroscopy measurements of oxidative function and postexercise recovery kinetics in the medial gastrocnemius muscle. Appl Physiol Nutr Metab 2014; 39:521-9. [DOI: 10.1139/apnm-2013-0347] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The purpose of this study was to assess the reproducibility of resting blood flow, resting oxygen consumption, and mitochondrial capacity in skeletal muscle using near-infrared spectroscopy (NIRS). We also determined the influence of 2 exercise modalities (ergometer and rubber exercise bands) on the NIRS measurements. Fifteen young, healthy participants (5 female, 10 male) were tested on 2 nonconsecutive occasions within an 8-day period. The NIRS device was placed on the medial gastrocnemius. Venous and arterial occlusions were performed to obtain blood flow and oxygen consumption. A series of repeated arterial occlusions was used to measure the recovery kinetics of muscle oxygen consumption after ∼7–10 s of voluntary plantar flexion exercise. Resting blood flow had mean coefficients of variation (CV) of 42% and 38% for bands and ergometer, respectively, and resting metabolism had mean CVs of 17% and 12% for bands and ergometer, respectively. The recovery time constant of oxygen consumption (day 1 bands and ergometer: 23.2 ± 3.7 s, 27.6 ± 6.5 s, respectively; day 2 bands and ergometer: 25.5 ± 5.4 s, 25.0 ± 4.9 s, respectively) had mean CVs of 10% and 11% for bands and ergometer, respectively. We conclude that measurements of oxygen consumption and mitochondrial capacity using NIRS can be obtained with good reproducibility.
Collapse
Affiliation(s)
- William M. Southern
- Department of Kinesiology, University of Georgia, 330 River Rd., Athens, GA 30602, USA
| | - Terence E. Ryan
- Department of Kinesiology, University of Georgia, 330 River Rd., Athens, GA 30602, USA
| | - Mary A. Reynolds
- Department of Kinesiology, University of Georgia, 330 River Rd., Athens, GA 30602, USA
| | - Kevin McCully
- Department of Kinesiology, University of Georgia, 330 River Rd., Athens, GA 30602, USA
| |
Collapse
|
41
|
Schmid AI, Schewzow K, Fiedler GB, Goluch S, Laistler E, Wolzt M, Moser E, Meyerspeer M. Exercising calf muscle T₂∗ changes correlate with pH, PCr recovery and maximum oxidative phosphorylation. NMR IN BIOMEDICINE 2014; 27:553-60. [PMID: 24610788 PMCID: PMC4260669 DOI: 10.1002/nbm.3092] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/13/2014] [Accepted: 01/17/2014] [Indexed: 05/12/2023]
Abstract
Skeletal muscle metabolism is impaired in disorders like diabetes mellitus or peripheral vascular disease. The skeletal muscle echo planar imaging (EPI) signal (S(EPI) ) and its relation to energy metabolism are still debated. Localised ³¹P MRS and S(EPI) data from gastrocnemius medialis of 19 healthy subjects were combined in one scanning session to study direct relationships between phosphocreatine (PCr), pH kinetics and parameters of T₂∗ time courses. Dynamic spectroscopy (semi-LASER) and EPI were performed immediately before, during and after 5 min of plantar flexions. Data were acquired in a 7 T MR scanner equipped with a custom-built ergometer and a dedicated ³¹P/¹H radio frequency (RF) coil array. Using a form-fitted multi-channel ³¹P/¹H coil array resulted in high signal-to-noise ratio (SNR). PCr and pH in the gastrocnemius medialis muscle were quantified from each ³¹P spectrum, acquired every 6 s. During exercise, SEPI (t) was found to be a linear function of tissue pH(t) (cross-correlation r = -0.85 ± 0.07). Strong Pearson's correlations were observed between post exercise time-to-peak (TTP) of SEPI and (a) the time constant of PCr recovery τPCr recovery (r = 0.89, p < 10⁻⁶), (b) maximum oxidative phosphorylation using the linear model, Q(max, lin) (r = 0.65, p = 0.002), the adenosine-diphosphate-driven model, Q(max,ADP) (r = 0.73, p = 0.0002) and (c) end exercise pH (r = 0.60, p = 0.005). Based on combined accurately localised ³¹P MRS and T₂∗ weighted MRI, both with high temporal resolution, strong correlations of the skeletal muscle SEPI during exercise and tissue pH time courses and of post exercise SEPI and parameters of energy metabolism were observed. In conclusion, a tight coupling between skeletal muscle metabolic activity and tissue T₂∗ signal weighting, probably induced by osmotically driven water shift, exists and can be measured non-invasively, using NMR at 7 T.
Collapse
Affiliation(s)
- Albrecht Ingo Schmid
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Kiril Schewzow
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Georg Bernd Fiedler
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Sigrun Goluch
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Elmar Laistler
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Michael Wolzt
- Department of Clinical Pharmacology, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
| | - Ewald Moser
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| | - Martin Meyerspeer
- Center for Medical Physics and Biomedical Engineering, Medical University of ViennaWähringer Gürtel 18-20, 1090, Wien, Austria
- MR Centre of Excellence, Medical University of ViennaLazarettgasee 14, 1090, Wien, Austria
| |
Collapse
|