Exercise Response Variation: Avoiding Hysteron Proteron

ABSTRACT Precision exercise medicine is currently one of the most important topics in the clinical exercise physiology field, including exercise-based cardiac rehabilitation (EBCR). A critical component of precision exercise medicine is an appropriate examination for true exercise-associated interindividual response differences (IIRDs) because of EBCR, something that has historically not occurred. As a result, misguided efforts aimed at determining potential moderators and mediators, including genetic interactions and unethical follow-up studies, can occur given that random- and within-subject variation is not accounted for. In this article, a description is provided on how to properly test for true exercise-associated IIRDs in original randomized controlled trials (RCTs) using the standard deviation of individual response (SD IR ) approach before deciding on whether an additional examination and/or follow-up studies addressing potential moderators and mediators, including genetic interactions, are necessary. To provide greater readability for a wider audience, we intentionally minimized the use of statistical formulas. It is the hope that the guidance provided in this article will lead to wider adoption of the SD IR approach for examining true IIRDs in original RCTs of EBCR studies as well as spur continued research on this topic. Adherence to the proposed methods will help avoid false conclusions regarding potential moderators and mediators, including genetic interactions, as well as unneeded follow-up studies.