Acute Effects of Novel Rest Interval Strategies in Resistance Training on Exercise -Related Outcomes Across Young, Older, and Clinical Cohorts

Abstract

Resistance training (RT) is essential for improving neuromuscular function and functional capacity, yet the optimal manipulation of rest intervals (RI) remains poorly understood across diverse populations. Novel strategies, such as blood flow restriction during rest intervals (BFR-RI) and cluster sets (CS), have recently emerged in the literature. This thesis investigated the acute effects of BFR-RI and CS on various exercise-related outcomes in healthy young adults, older adults, and individuals with Charcot-Marie-Tooth disease (CMT), a population susceptible to fatigue and functional impairment.

Chapter 3 examined BFR-RI during high-load squats in trained young adults. BFR-RI produced similar mechanical, perceptual, and physiological responses to conventional RT, with a small but significant reduction in total repetitions, indicating slightly accelerated fatigue. Chapters 4–6 compared CS versus traditional sets (TRAD) during chest press (CP) and leg press (LP). Across populations, CS generally preserved mean concentric velocity (MCV), attenuated MCV loss - particularly in CP - and increased estimated repetitions to failure. Reductions in rating of perceived exertion were only observed in young adults, and lower-functioning CMT participants were more likely to terminate CP sets early. The study in young adults elucidates minimal sex and strength impact on MCV attenuation.

Overall, CS improved acute performance and mitigated neuromuscular fatigue, particularly during CP, whereas BFR-RI offered minimal advantage over conventional RT. These findings highlight RI as a key training variable and support CS as a practical strategy to maintain performance and potentially reduce neuromuscular fatigue in healthy and clinical populations. Future research should explore individualized CS protocols, alternative set structures, and long-term adaptations to optimize outcomes, safety, and adherence, especially in populations vulnerable to fatigue or functional limitations.