Cross-sectional studies have previously shown that there is a positive association between maximal oxygen uptake (VO2max) and non-exercise activity thermogenesis (NEAT). However data on how an increase in VO2max affects NEAT or total daily energy expenditure in a sedentary population are scarce. The primary aim of this study was to investigate the effect of 6 weeks of high intensity interval training on VO2max and daily total energy expenditure in initially sedentary male subjects of normal weight. Thirty healthy sedentary males (39.1 ± 5.9 yrs and BMI 25.5 ± 2.6 kg/m2) performed aerobic endurance training on treadmills three times per week for a total of six weeks. The subjects were randomized to one of the following protocols: one interval (4 minutes) of high intensity training (HIIT-1) performed at 85-95% of maximal heart rate (HRmax), four intervals (each lasting 4 minutes) of high intensity training (HIIT-4) performed at 85-95% HRmax and a control group performing moderate continuous training (47 minutes) at 70% HRmax (MCT). Daily total energy expenditure (TEE), number of steps (Senswear, armband), VO2max and body composition were measured before and after the intervention. Values are Means+SD compared by ANCOVA for differences between groups and paired sample t test for within group differences. There was a significant increase in VO2max after HIIT-1 (from 44.5 ± 6.6 mLxkg-1xmin-1 to 47.7 ± 7.7 mLxkg-1xmin-1, p<0.05) and HIIT-4 (from 43.1 ± 5.4 mLxkg-1xmin-1 to 47.1 ± 5.7 mLxkg-1xmin-1,p<0.05) with no change in the MCT group. No change in daily energy expenditure or number of steps was observed after HIIT-1 and HIIT-4. However, daily total energy expenditure was increased by 14% after MCT (from 2557 ± 312 calories to 2921 ± 394 calories). Six weeks of HIIT-4 induced a significant decrease in body fat (from 22.4 ± 8.4 to 20.7 ± 8.4 after, p< 0.05). In the initial phase of structured exercise training, an increase in VO2max has no effect on daily activity level in untrained men. Importantly, this study shows that short bouts of high intensity interval training may be just as effective as longer interval training to increase VO2max for sedentary middle-aged men.
The Biomedical Basis of Elite Performance (London) (2012) Proc Physiol Soc 26, PC53
Poster Communications: Increase in maximal oxygen uptake in the fight against inactivity?
N. Zisko3,1, D. Stensvold1,2, T. Karlsen1,3, U. Wisloff1,4
1. Circulation and medical imaging, Norwegian University of Science and Technology, Trondheim, Norway. 2. Circulation and medical imaging, Norwegian University of Science and Technology, Trondheim, Norway. 3. Circulation and medical imaging, Norwegian University of Science and Technology, Trondheim, Norway. 4. Circulation and medical imaging, Norwegian University of Science and Technology, Trondheim, Norway.
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Where applicable, experiments conform with Society ethical requirements.