Examining Interindividual Differences in Select Muscle and Whole-Body Adaptations to Continuous Endurance Training
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Authors
Bonafiglia, Jacob T.
Islam, Hashim
Preobrazenski, Nicholas
Ma, Andrew
Deschenes, Madeleine
Erlich, Avigail T.
Quadrilatero, Joe
Hood, David
Gurd, Brendon J.
Date
2021-05-16
Type
journal article
Language
en
Keyword
SDIR , Individual responses , Aerobic exercise training , Interindividual variability
Alternative Title
Abstract
Studies have interpreted a wide range of morphological and molecular changes in human skeletal muscle as evidence of interindividual differences in trainability. However, these interpretations fail to account for the influence of random measurement error and within-subject variability. The purpose of the present study was to use the standard deviation of individual response (SDIR) statistic to test the hypothesis that interindividual differences in trainability are present for some but not all skeletal muscle outcomes. Twenty-nine recreationally-active males (age: 21±2 years; BMI: 24±3; VO2peak: 45±7 mL/kg/min) completed four weeks of continuous training (REL; n = 14) or control (CTRL; n = 15). Maximal enzyme activities (citrate synthase and β-HAD), capillary density, fibre type composition, fibre-specific SDH activity and substrate storage (IMTG and glycogen), and markers of mitophagy (BNIP3, NIX, PRKN, and PINK1) were measured in vastus lateralis samples collected before and after the intervention. We also calculated SDIR values for VO2peak, peak work rate, and the onset of blood lactate accumulation for REL and a separate group that exercised at the negative talk test (TT) stage. Although positive SDIR values – indicating interindividual differences in trainability – were obtained for aerobic capacity outcomes, maximal enzyme activities, capillary density, all fibre-specific outcomes, and BNIP3 protein content, the remaining outcomes produced negative SDIR values indicating a large degree of random measurement error and/or within-subject variability. Our findings question the interpretation of heterogeneity in observed responses as evidence of interindividual differences in trainability and highlight the importance of including control groups when analyzing individual skeletal muscle response to exercise training.
Description
This is the peer reviewed version of the following article: Bonafiglia, J.T., Islam, H., Preobrazenski, N., Ma, A., Deschenes, M., Erlich, A.T., Quadrilatero, J., Hood, D.A. and Gurd, B.J. (2021), Examining interindividual differences in select muscle and whole-body adaptations to continuous endurance training. Exp Physiol. Accepted Author Manuscript. https://doi.org/10.1113/EP089421, which has been published in final form at https://doi.org/10.1113/EP089421. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.
Citation
Bonafiglia, J.T., Islam, H., Preobrazenski, N., Ma, A., Deschenes, M., Erlich, A.T., Quadrilatero, J., Hood, D.A. and Gurd, B.J. (2021), Examining interindividual differences in select muscle and whole-body adaptations to continuous endurance training. Exp Physiol. Accepted Author Manuscript. https://doi.org/10.1113/EP089421
Publisher
Wiley