标题：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：Highlights
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This is the first study showing that 6 high-intensity interval training (HIIT) sessions over just 5 days is just as effective in increasing maximal oxygen uptake and endurance capacity and is more effective at improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.
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Five days of HIIT that lasts 60 min in total may be a potent stimulus to improve exercise performance and substrate oxidation.
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Our findings reveal that this protocol achieves the fastest adaptation in response to a HIIT regime.
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This study represents an important conceptual advance in demonstrating the remarkable ability of the human body to adapt to exercise stress in less than 2 weeks.
Background
High-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 (VO
2max), 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 VO
2max, submaximal exercise fat oxidation, and endurance capacity as effectively as 6 sessions of HIIT over 2 weeks (single HIIT (HIIT-S),
n = 13).
Methods
Each training session consisted of 10 × 60 s of cycling at 100% of VO
2max interspersed with 75 s of low-intensity cycling at 60 watt (W). Pre- and post-training assessments included VO
2max, time to exhaustion at
∼80% of VO
2max, and 60-min cycling trials at
∼67% of VO
2max.
Results
Similar increases (
p < 0.05) in VO
2max (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 = 0.014
vs. 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).
Conclusion
Six HIIT sessions over 5 days was as effective in increasing VO
2max and endurance capacity and was more effective in improving submaximal exercise fat oxidation than 6 HIIT sessions over 2 weeks.
Graphic Abstract
Image, graphical abstract
