Stubborn Exercise Responders-Where to Next?
Level 5 - mechanism / opinion, no new human data
Narrative review and conceptual proposal without systematic methodology or primary data
PubMed 35736835 · doi:10.3390/sports10060095
What was done
This narrative review examined the phenomenon of inter-individual variability in physiological adaptations to endurance and resistance training. The authors evaluated literature regarding the prevalence of reported non-responders, the effect of modifying training variables (frequency, intensity, type, and duration), multi-variable health tracking, and candidate biomarkers (e.g., exerkines, metabolomics, DNA damage, genetics, epigenetics) to identify individuals who require tailored exercise prescriptions.
What was found
The abstract reports that up to 40% of participants in some project samples are classified as "poor" or "non" responders. However, adjusting exercise frequency, intensity, type, or duration ameliorates poor response rates. Furthermore, global non-response is eliminated when assessing multiple health metrics simultaneously. When endurance training frequency is increased, cardiorespiratory fitness improvements in initial low-responders match those of high-responders. No quantitative pooled effect sizes, confidence intervals, or specific statistical test outputs were provided in the abstract.
Why it matters
The paper advocates replacing the fatalistic label of "poor responder" or "non-responder" with "stubborn responder," emphasizing that resistance or endurance training adaptations can usually be achieved by personalizing volume, frequency, or intensity rather than assuming an individual is inherently incapable of adaptation.
Limits
The abstract describes a narrative review and perspective piece rather than a systematic review or empirical study, lacking quantitative synthesis, risk-of-bias assessment, or pooled effect estimates. It relies on conceptual proposals for future biomarker screening panels that have not yet been clinically validated or tested for cost-effectiveness.
Cited by
- context Approximately 40% of people do not show significant cardiorespiratory fitness improvement from standard moderate-intensity cardiovascular exercise alone (non-responders).