Equity in training load: research design considerations for intervention assessment in sports science and physical...

Training load (TL) assessment and management are important in athletic training, physical therapy, and sports science, as exercise-induced responses to the exercise stimulus depend on the dose of the applied exercise stimulus. Different TL may result in distinct adaptation, intervention feasibility, or injury risks, amongst other considerations. However, often studies are based on interventions with different TL between the groups, possibly influencing the research outcomes. This opinion paper discusses scenarios where TL matching may be beneficial, and presents literature exemplary cases from respiratory muscle training, strength training in endurance athletes, and exercise-based physical therapy. Moreover, the contextual role of TL in different populations and possible solutions regarding study design are discussed. We conclude that the considerations of TL assessment in research design may be beneficial for comparative experimental studies, crossover, and counterbalanced trials in sports sciences and physical therapy. By acknowledging and reconciling TL differences, researchers can elevate the relevance of their findings. Consequently, the effects of an intervention can be attributed to the type of intervention rather than confounded by differences in TL between groups.