Mixed
Standardized exercise training produces highly variable cardiorespiratory fitness (CRF) responses in humans, with a significant portion of individuals showing no improvement (non-responders) despite adherence to prescribed protocols.
If you exercise consistently but see no change in your fitness tests, you are likely a 'non-responder' to that specific dose. This is common and often genetic. Do not stop exercising, as other health benefits likely persist. Consider adjusting the type, intensity, or duration of exercise to find a protocol that works for your biology.
findings from numerous investigations demonstrate an extraordinary interindividual variability in response to a standard dose of exercise wherein a substantial number of adults do not improve CRF beyond the day-to-day variability in response to physical activity consistent with current recommendations.
Why this rating
Based on a consensus statement reviewing multiple human twin/family studies, animal selection experiments, and RCTs.
Source
Precision exercise medicine: understanding exercise response variability
Robert Ross et al. · British Journal of Sports Medicine · 2019
DOI 10.1136/bjsports-2018-100328
More from this paper
- Genetic factors account for 30-60% of the variance in cardiorespiratory fitness response to exercise training in humans.Strong
- Defining 'non-responders' is methodologically challenging and depends heavily on the threshold used (e.g., measurement error vs. clinical significance), leading to inconsistent classification across studies.Good
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