BACKGROUND Free-living adherence to high-intensity interval training (HIIT) has not been adequately tested. This randomized trial examined changes in cardiorespiratory fitness (CRF) and accelerometer-measured purposeful physical activity over 12 months of free-living HIIT versus moderate-intensity continuous training (MICT). METHODS Ninety-nine previously low-active participants with overweight/obesity were randomly assigned to HIIT (n = 47) or MICT (n = 52). Both interventions were combined with evidence-based behaviour change counselling consisting of 7 sessions over 2 weeks. Individuals in HIIT were prescribed 10 X 1-min interval-based exercise 3 times per week (totalling 75 min) whereas individuals in MICT were prescribed 150 min of steady-state exercise per week (50 mins 3 times per week). Using a maximal cycling test to exhaustion with expired gas analyses, CRF was assessed at baseline and after 6 and 12 months of free-living exercise. Moderate-to-vigorous physical activity of 10+ minutes (MVPA10+) was assessed by 7-day accelerometry at baseline, 3, 6, 9, and 12 months. Intention to treat analyses were conducted using linear mixed models. RESULTS CRF was improved over the 12 months relative to baseline in both HIIT (+ 0.15 l/min, 95% CI 0.08 to 0.23) and MICT (+ 0.11 l/min, 95% CI 0.05 to 0.18). Both groups improved 12-month MVPA10+ above baseline (HIIT: + 36 min/week, 95% CI 17 to 54; MICT: + 69 min/week, 95% CI 49 to 89) with the increase being greater (by 33 min, 95% CI 6 to 60) in MICT (between group difference, P = 0.018). CONCLUSION Despite being prescribed twice as many minutes of exercise and accumulating significantly more purposeful exercise, CRF improvements were similar across 12 months of free-living HIIT and MICT in previously low-active individuals with overweight/obesity.

中文翻译：

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自由生活的高强度间歇训练和中强度连续训练一年后的心肺健康和加速度计确定的身体活动：一项随机试验。

背景技术尚未充分测试对高强度间歇训练（HIIT）的自由活动依从性。这项随机试验研究了自由活动HIIT与中等强度连续训练（MICT）在12个月内心肺健康（CRF）和加速度计测量的有目的体育活动的变化。方法随机将99例超重/肥胖的低活动参与者随机分为HIIT（n = 47）或MICT（n = 52）。两种干预措施均与基于证据的行为改变咨询相结合，在2周内共进行了7次。在HIIT中，个人被规定每周进行3次10 X 1分钟基于间隔的运动（总计75分钟），而在MICT中的人被规定进行每周150分钟的稳态运动（每周50次，进行3次）。使用最大的循环测试以用尽过期的气体分析进行疲劳消耗，在基线以及自由活动运动6和12个月后评估CRF。在基线，3、6、9和12个月时，通过7天的加速度计评估了10到10分钟的中度到剧烈的身体活动（MVPA10 +）。使用线性混合模型进行治疗意向分析。结果HIIT（+ 0.15 l / min，95％CI 0.08至0.23）和MICT（+ 0.11 l / min，95％CI 0.05至0.18）相对于基线在12个月内CRF均得到改善。两组均较基线提高了12个月MVPA10 +（HIIT：+ 36分钟/周，95％CI为17至54； MICT：+69分钟/周，95％CI为49-89），且增加幅度更大（增加了33分钟， 95％CI 6至60）（两组之间的差异，P = 0.018）。