Vertical Strength Transfer Phenomenon Between Upper Body and Lower Body Exercise: Systematic Scoping Review

Abstract

Background. There are myriad of exercise variations in which upper body (UB) and lower body (LB) exercises have been intermittently used. However, it is still unclear how training of one body region (e.g., LB) affects adaptations in distant body areas (e.g., UB), and how different UB and LB exercise configurations could help facilitate physiological adaptations of either region; both referred to in this review as vertical strength transfer (VST). Objective. To investigate the existence of the VST phenomenon as a response to various UB and LB exercise configurations and to identify potential mechanisms underpinning its occurrence. Methods. A systematic search using the PRISMA Scoping Review protocol was conducted in February 2024 using four databases (Web of Science, MEDLINE, Scopus and CINAHL) to identify peer-reviewed articles that investigated the VST phenomenon. Results. Of the 5,242 identified articles, 24 studies met the inclusion criteria. Findings suggest that the addition of UB strength training to LB endurance exercise may help preserve power-generating capacity for the leg muscle fibres. Furthermore, systemic endocrine responses to high-volume resistance exercise may beneficially modulate adaptations in precedingly or subsequently trained muscles from a different body region, augmenting their strength gains. Lastly, strength training for LB could result in improved strength of untrained UB, likely due to the increased central neural drive. Conclusion. VST existence is enabled by neuro-physiological mechanisms. Future research should involve athletic population, examining the potential of VST to facilitate athletic performance and preserve strength in injured extremities.