ACUTE EFFECT OF INTERVAL TRAINING SET STRUCTURE ON PHYSIOLOGICAL AND PERCEPTUAL RESPONSES TO EXERCISE

Abstract

INTRODUCTION & AIMS A novel method for prescribing maximal aerobic speed (MAS) interval sessions involves the use of rest redistribution (RR). This approach could reduce perceived exertion and fatigue, preventing a decline in performance. This study aimed to compare acute physiological and perceptual responses between traditional (TS) and RR MAS interval training in endurance athletes. METHODS Twenty-five endurance runners (19 males, 6 females; age=31.9±8.5 y; maximal oxygen consumption (V̇O2max)=54.6±5.7 ml·kg·min-1; height=1.77±0.10 m; body-mass=74.0±13.0 kg) who ran >5 hours/week participated. Participants completed two MAS interval sessions equal in duration (18 min total, 360 s exercise, TS=660 s rest/RR=680 s rest) in a randomised order; TS: 3 sets x 6 repetitions (1 rep=20 s running:20 s rest) at 110% MAS and RR: 18 sets x 1 repetition (20 s running:40 s rest) at 110% MAS. During both sessions V̇O2 and heart rate (HR) were measured after each repetition, and blood lactate (HLa-) measured pre-exercise and after repetitions 6, 12 and 18. Rating of perceived exertion (RPE) was measured after repetitions 6, 12, and 18, and overall session RPE 10 minutes post-session. RESULTS Linear mixed effects models showed that TS led to a faster increase in V̇O2 (β=.16, p=.04) and HLa- (β=.09, p<.01), with consistently higher HR than RR (β=5.35, p<.01). Additionally, RPE (β=1.35, p<.01) and session RPE were lower in RR than TS (β=1.13, p<.01). CONCLUSION Results indicate that when session time is similar, TS (1:1 work-to-rest ratio), produces a greater physiological stimulus with higher V̇O2, HR and HLa-. Conversely, RR (1:2 work-to-rest ratio) resulted in lower perceived exertion and metabolic stress. This makes RR an appropriate choice for training periods with lower physiological stress or during periods of fatigue management. The reduced physiological demands in RR can facilitate a more controlled and sustainable training experience while still providing valuable training benefits.