Exercise snacks are a time-efficient alternative to moderate-intensity continuous training for improving cardiorespiratory fitness but not maximal fat oxidation in inactive adults: a randomized controlled trial
Mingyue Yin, Shengji Deng, Zhili Chen, Boyi Zhang, Huakun Zheng, Mingyang Bai, Hansen Li, Xing Zhang, Jianfeng Deng, Qian Liu, Jonathan P. Little, Yongming Li
Abstract
The aims of this study were (1) to determine how stair-climbing-based exercise snacks (ES) compared to moderate-intensity continuous training (MICT) for improving cardiorespiratory fitness (CRF), and (2) to explore whether ES could improve maximal fat oxidation rate (MFO) in inactive adults. Healthy, young, inactive adults ( n: 42, age: 21.6 ± 2.3 years, BMI: 22.5 ± 3.6 kg·m −2 , peak oxygen uptake (VO 2 peak): 33.6 ± 6.3 mL·kg −1 ·min −1 ) were randomly assigned to ES, MICT, or Control. ES ( n = 14) and MICT ( n = 13) groups performed three sessions per week over 6 weeks, while the control group ( n = 15) maintained their habitual lifestyle. ES involved 3 × 30 s “all-out” stair-climbing (6 flight, 126 steps, and 18.9 m total height) bouts separated by >1 h rest, and MICT involved 40 min × 60%–70% HR max stationary cycling. A significant group × time interaction was found for relative VO 2 peak ( p < 0.05) with ES significantly increasing by 7% compared to baseline (MD = 2.5 mL·kg −1 ·min −1 (95% CI = 1.2, 3.7), Cohen’s d = 0.44), while MICT had no significant effects (MD = 1.0 mL·kg −1 ·min −1 (−1.1, 3.2), Cohen’s d = 0.17), and Control experienced a significant decrease (MD = −1.7 mL·kg −1 ·min −1 (−2.9, −0.4), Cohen’s d = 0.26). MFO was unchanged among the three groups (group × time interaction, p > 0.05 for all). Stair climbing-based ES are a time-efficient alternative to MICT for improving CRF among inactive adults, but the tested ES intervention appears to have limited potential to increase MFO.