Causes and Consequences of Interindividual Response Variability: A Call to Apply a More Rigorous Research Design in Acute Exercise-Cognition Studies

Abstract

The different responses of humans to an apparently equivalent stimulus are called interindividual response variability. This phenomenon has gained more and more attention in research in recent years. The research field of exercise-cognition has also taken up this topic, as shown by a growing number of studies published in the past decade. In this perspective article, we aim to prompt the progress of this research field by (i) discussing the causes and consequences of interindividual variability, (ii) critically examining published studies that have investigated interindividual variability of neurocognitive outcome parameters in response to acute physical exercises, and (iii) providing recommendations for future studies, based on our critical examination. The provided recommendations, which advocate for a more rigorous study design, are intended to help researchers in the field to design studies allowing them to draw robust conclusions. This, in turn, is very likely to foster the development of this research field and the practical application of the findings.

Acute and Chronic Exercise Effects on Human Memory: What We Know and Where to Go from Here

“…Individual Factors . Although not an exhaustive list, various individual-level factors may influence the exercise–memory relationship, such as age, biological sex, cardiorespiratory fitness, individual differences in memory function, and BDNF genotype; for other factors to consider, see work by Herold et al [ 51 ]. Age appears to be an important moderator of the effects of exercise on memory.…”

“…As such, the method used to determine the intensity of exercise should be carefully considered. For specific recommendations, the reader is referred elsewhere [ 51 , 87 , 88 ].…”

Tai Chi practice enables prefrontal cortex bilateral activation and gait performance prioritization during dual-task negotiating obstacle in older adults

“…Fourth, this study recruited participants in a narrow age range from 65 to 75 to avoid the influences of heterogeneity among older adults, which may affect the applicability of our outcomes to other age populations. Fifth, consequence of interindividual response variability should be considered for future studies as these variables are linked to exercise-induced benefits (Herold et al, 2021). Lastly, eye-based measures are recently recommended by a group of experts exercise-cognition field as they can be used in combination with fNIRS, leading to more reliable findings.…”

Acute effects of virtual reality treadmill training on gait and cognition in older adults: A randomized controlled trial

“…This proof-of-concept study was a parallel-group, single-blind, stratified randomized controlled trial with 1:1 allocation ratio. The randomization was stratified on gender, to control for established gait speed differences between males and females and the established influence of gender on exercise-related responses [ 47 , 48 ]. The randomization sequence was computer-generated and created by one of the authors before the start of the study.…”