HIIT training has higher reinforcing value than moderate intensity aerobic exercise for sedentary adults

Authors: EPSTEIN, LEONARD - University Of Buffalo; O'DONNELL, SARA - University Of Buffalo; CARR, KATELYN - University Of Buffalo; BIONDOLILLO, MATHEW - University Of Buffalo; HOSTLER, DAVID - University Of Buffalo; Roemmich, James

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/4/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Purpose: Exercise confers numerous physical and mental health benefits yet the majority of adults are inactive. Exercise can be studied as a reinforcing stimulus; research shows that adults who find exercise more reinforcing engage in greater objectively-measured physical activity. High intensity interval training (HIIT) involves exercising at repeated high and low-intensity intervals, and has emerged as an alternative to traditional moderate intensity aerobic exercise (MIAE) because it produces fitness benefits in less time. Research shows people prefer HIIT over MIAE, possibly due to the observed affective changes, whereby affect decreases during exercise and increases post-exercise. The primary purposes of this study were to compare the reinforcing value (RRV) of HIIT versus MIAE in a sample of sedentary adults, and investigate whether affect during or post-exercise was more strongly related to the RRV of HIIT. Methods: Female participants (n=20; Mage=30.5, SD=8.5; 30% minority) were randomized to one of two groups that structured HIIT to be 50 or 100% of MIAE to investigate the effect of time engaging in HIIT on RRV. Participants were scheduled for six sessions, during which they completed a fitness test to individualize treadmill workloads (Session 1), completed a RRV task twice for each mode of exercise to assess repeatability and change over sessions (Session 2-5), and a 10-minute HIIT workout (10 repetitions of 30s HIIT, 30s recovery) to measure affect during and post-exercise (Session 6). Results: Results showed reliable differences in RRV across exercise mode (F(1,18)=9.95, p=0.005). No effect of group (p=0.36) or session number (p=0.12) was observed. Participants reported higher liking ratings for HIIT (7.3+1.5) versus MIAE (5.5+1.6) (F(1,18)=12.15, p=0.003). Correlations between RRV values for MIAE and for HIIT across the two sessions was 0.72 and 0.96, p’s<0.001. Affect during HIIT exercise showed a significant change over time (F(9,162)=9.13, p<0.001) and was significantly related to RRV of HIIT (F(1,80)=4.85, p=0.03), preference (F(1,80)=4.96, p=0.029) and tolerance (F(1,80)=7.43, p=0.008) for intense exercise, and liking of HIIT exercise (F(1,80)=5.15, p=0.026). Discussion: People will engage in activities that are easily accessible and are the most reinforcing. Beyond reducing environmental barriers to exercise participation, a novel approach to increasing activity levels amongst sedentary adults may be to develop exercise programs that are the most reinforcing for the most people. Results of the current study show that HIIT was reliably more reinforcing than MIAE among sedentary female adults. The greater reinforcing value of exercise was not related to the shorter time intervals for HIIT versus MIAE, since there was no difference in RRV whether HIIT took the same amount of time as MIAE or half the time. Our data show that the reinforcing value of HIIT was significantly related to affect during exercise, and unrelated to post-exercise affect, suggesting that exercise programs that maximize positive affect during exercise bouts may be stronger reinforcers. HIIT may be a innovative exercise program that can serve as a reinforcer to motivate physical activity.