S. Seiler and K.J. Hetlelid (2005). The impact of rest duration on work intensity and RPE during interval training. Medicine and Science in Sports and Exercise, 37, 1601-1607.
Purpose: to investigate the effect of rest duration on self-selected intensity, physiological responses and RPE during a standardised, high-intensity interval training prescription. Subjects: nine well-trained male runners (VO2max 71+/-4 ml.kg-1.min-1) performed three treadmill interval training sessions running at constant 5% inclination. Six 4-min work bouts with either 1-, 2-, or 4-min recovery periods were performed in each session. Sessions were prescribed as “high-intensity” workouts with the goal being to achieve the highest possible average running speed for the work intervals. Subjects regulated their work and rest intensity based on these instructions. In a fourth interval session, subjects self-selected recovery time in response to a fixed intensity. Results: running velocity increased slightly (14.7+/-0.7 vs. 14.4+/-0.8 km.h-1), when rest increased from 1 to 2 min, but showed no further increase with a 4-min rest (14.7+/-0.6 km.h-1). Work VO2 was slightly higher with a 2-min rest duration compared with 1 and 4 min (66.2+/-4.2 vs. 65.1+/-4.2 and 64.9+/-4.7 ml.kg-1.min-1). Peak blood lactate was similar (6.2+/-2.6, 6.8+/-2.9 and 6.2+/-2.6 mmol.l-1) across conditions, whereas peak RPE was slightly lower during the 4-min rest condition (17.1+/-1.3, 17.7+/-1.5, 16.8+/-1.5). With self-selected recovery time and no knowledge of elapsed time, the average rest duration was 118+/-23 sec. Conclusions: under self-paced conditions, varying rest duration in a range of 1 to 4 min had limited impact on performance during repeated 4-min high-intensity exercise bouts. Approximately 120 sec of active recovery may provide an appropriate balance between intracellular restitution and maintenance of high VO2 on-kinetics.
