Author(s): PARK, J.H., WE, H., LEE, S., SEO, Y., YUN, S., LEE, D.T., Institution: KOOKMIN UNIVERSITY, Country: KOREA, SOUTH, Abstract-ID: 1581

INTRODUCTION:
The inter-set interval is crucial in resistance training for the development of hypertrophy and muscular strength. However, the effect of inter-set interval in resistance training for energy expenditure has not been extensively studied. This study aimed to investigate the inter-set interval during bench press on oxygen uptake and heart rate.
METHODS:
16 healthy men (23.6±1.9 years, 174.9±3.4 cm, 76.0±10.0 kg) underwent three tests. During each testing, they performed three sets of bench press at their 70% (53.3±14.3 kg) of one-repetition maximum (1RM) with three different inter-set intervals; 2 (2M), 5 (5M), and 10 min (10M). Each testing was separated at least 2 days, and the order was balanced. Prior to the first testing, their height, weight, and 1RM were measured directly. During testing, oxygen uptake (VO2) and heart rate (HR) were continuously monitored, and repetitions at each set were counted.
RESULTS:
Testing at 2M, 5M, and 10M lasted 465±33, 1015±30, and 1923±29 sec, respectively. The repetitions at 2M, 5M, and 10M were 18±5, 17±4, and 17±4 (at 1st set), 8±3, 12±4, and 15±4 (at 2nd set), and 5±3, 9±3, and 12±3 (at 3rd set), respectively. The average VO2 during testing at 2M, 5M, and 10M was 11.2±1.3, 9.7±1.5, and 9.1±1.1 ml/kg/min, respectively (p<0.001). The average VO2 of 3 inter-set intervals at 2M (12.7±1.9 ml/kg/min) was higher than 5M (9.1±1.4) and 10M (7.5±1.0) (p<0.001). However, no differences were found in average VO2 of bench press exercise between 2M (9.7±1.6), 5M (10.4±2.0), and 10M (10.6±1.5 ml/kg/min). There were no significantly differences in average HR during testing between 2M (102±14), 5M (101±12), and 10M (97±13 beats/min).
CONCLUSION:
The results revealed that the shorter inter-set rest interval during bench press exercise showed a higher oxygen uptake without changing heart rate. It implies that, if there is no specific training purpose, a shorter inter-set rest intervals during resistance exercise would lead to an increased energy expenditure per unit time.