Inter-Individual Heterogeneity in Aerobic Training Adaptations: Systematic Review of the Evidence Base for Personalized Exercise Prescription

Personalized exercise prescriptions require identifying inter-individual differences in exercise intervention effects. This review examined whether true inter-individual differences exist after accounting for measurement error. PubMed, Web of Science, and EMBASE databases were systematically searched. Inclusion criteria included: (1) original randomized controlled trials or controlled trials using standardized, supervised aerobic exercise interventions, or meta-analyses examining inter-individual differences in aerobic training adaptations; (2) explicitly identifying the assessment of inter-individual response variability as a research objective; (3) Reporting sufficient statistical information to quantify inter-individual variability. The search yielded a total of 3203 studies, and ultimately 78 studies were included for systematic review. Main findings included: (1) Few studies appropriately considered random measurement error and within-individual variability when quantifying inter-individual differences. (2) Analysis of both primary studies and existing meta-analyses revealed a consistent lack of statistical evidence for true inter-individual differences. (3) Observed inter-individual variability was primarily attributed to uncontrolled measurement error or within-individual variability, not true individual response differences. The evidence analyzed in this systematic review indicates that there is insufficient support for true inter-individual differences in the effects of aerobic exercise training intervention. Given physiological complexity and methodological limitations, any conclusions on exercise intervention heterogeneity or individual responsiveness require caution.

This systematic review evaluates inter-individual differences in aerobic training adaptations for personalized exercise prescriptions.