低運動量高強度間歇訓練對久坐成年族群最大攝氧量的效益

Effects of low volume high intensity interval training protocols for V‧O2max improvements in sedentary adults

提高身體活動量可以降低非傳染性疾病導致的失能及死亡風險，但因缺乏時間運動導致身體活動量不足，仍高居全球死亡率的第四大危險因素。越來越多的研究顯示高強度間歇訓練（high-intensity interval training, HIIT）可縮短訓練總時間，並達到與中等強度連續訓練（moderate intensity continuous training, MICT）相似或更高的心肺適能，進而降低全因死亡率。但是獲得健康效益所需的精準運動量仍有爭議，因此搜尋近五年（2016～2020）HIIT相關研究，篩選受試者為久坐或運動不足的成年人（18～64歲），以及運動時間≦5分鐘的低運動量HIIT（low volume high intensity interval training, LV-HIIT）計畫，回顧分析最大攝氧量（maximal oxygen uptake, V‧O2max）調控效益。結果顯示減量高強度間歇訓練（reduced exertion high intensity interval training, REHIT），為一種更精簡時間的間歇衝刺訓練（interval training, SIT），每週2次8分鐘40秒的腳踏車測功計訓練，包含2分鐘的熱身（～25W）及2次20秒的全力衝刺，阻力為受試者體重的5％，每次衝刺後以3分鐘低強度運動恢復（～25W），持續六週即可有效增加7.4％ V‧O2max。若要降低運動強度，採取非最大強度LV-HIIT也是一種相對省時的訓練方式，將運動強度降低為85～95％最大心跳率（maximal heart rate, HRmax），並延長運動持續的時間至1分鐘，及間隔以1分鐘低強度運動恢復，重複5次，訓練包含2分鐘熱身及3分鐘緩和的低強度運動，單次訓練可於14分鐘內完成，持續訓練8週，每週2次，可增加27％ V‧O2max。每週2次，每次訓練時間≦15分鐘的LV-HIIT計畫，有助於缺乏時間的成年族群建立運動習慣。

Regular exercise reduces the risk of disability and death caused by non-communicable diseases. However, physical inactivity is now identified as the fourth leading risk factor for global mortality. The major barrier to exercise is lack of time. Research has shown that high intensity interval training (HIIT) is a time-efficient exercise strategy to provide similar benefits to moderate intensity continuous training (MICT) for improving cardiorespiratory fitness and thereby reducing all-cause mortality. The precise intensity and minimal session volume required to obtain health benefits is still controversial. Therefore, we searched for HIIT related studies in the past five years (2016~2020), and inclusion criteria were the subjects as sedentary or inactive adults (18-64 years old) and session volume £5 min of low volume HIIT (LV-HIIT) protocols, to examine the effects of those on V‧O2max improvements. The results show that performing reduced exertion high intensity interval training (REHIT) twice a week (8 min and 40s per session) for 6 weeks effectively improves V‧O2max by 7.4%. REHIT is a low volume sprint interval training (SIT) and performed on a cycle ergometer. Each session involved a 2-min warm-up (~25W), 2×20s ‘all-out' cycling sprints (resistance equivalent to 5% of the participant's body mass) and 3-min low-intensity recovery (~25W) following each sprint. To reduce exercise intensity, 5×1 HIIT, a submaximal intensity LV-HIIT, is also a feasible time-efficient approach. 5×1 HIIT consists of five 1-min bouts at 85~95% HRmax alternating with 1-min recovery at low intensity and lasts a total of 14 min per session (including 2-min warm-up and 3-min cool-down at low-intensity). Performing 5×1 HIIT twice per week improves V‧O2max by 27% over 8 weeks intervention period. Both LV-HIIT protocols with 2 sessions (£15 min) per week would help adults who lack time to build exercise habits.