Six high-intensity interval training sessions over 5 days increases maximal oxygen uptake, endurance capacity, and sub-maximal exercise fat oxidation as much as 6 high-intensity interval training sessions over 2 weeks

摘要

BackgroundHigh-intensity interval training (HIIT) induces similar or even superior adaptations compared to continuous endurance training. Indeed, just 6 HIIT sessions over 2 weeks significantly improves maximal oxygen uptake (VO2max), submaximal exercise fat oxidation, and endurance performance. Whether even faster adaptations can be achieved with HIIT is not known. Thus, we aimed to determine whether 2 sessions of HIIT per day, separated by 3 h, every other day for 5 days (double HIIT (HIIT-D),n?=?15) could increase VO2max, submaximal exercise fat oxidation, and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT (HIIT-S),n?=?13).MethodsEach training session consisted of 10 × 60 s of cycling at 100% of VO2maxinterspersed with 75 s of low-intensity cycling at 60 watt (W). Pre- and post-training assessments included VO2max, time to exhaustion at～80% of VO2max, and 60-min cycling trials at～67% of VO2max.ResultsSimilar increases (p< 0.05) in VO2max(HIIT-D: 7.7%vs.HIIT-S: 6.0%,p> 0.05) and endurance capacity (HIIT-D: 80.1%vs. HIIT-S: 79.2%,p> 0.05) were observed. Submaximal exercise carbohydrate oxidation was reduced in the 2 groups after exercise training (HIIT-D: 9.2%,p?=?0.014vs.HIIT-S: 18.8%,p?=?0.012) while submaximal exercise fat oxidation was significantly increased in HIIT-D (15.5%,p?=?0.048) but not in HIIT-S (9.3%,p?=?0.290).ConclusionSix HIIT sessions over 5 days was as effective in increasing VO2maxand endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.