The effect of low amount versus high amount interval training on maximal oxygen uptake
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- Institutt for biologi 
Introduction: Cardiorespiratory fitness (CRF) is a stronger predictor of cardiovascular mortality from cardiovascular disease (CVD) than the level of self-reported physical activity. CRF is measured as maximal (VO2max) or peak oxygen uptake (VO2peak), and the VO2max exercise test is considered to be the gold standard for measuring CRF. Low CRF is a modifiable factor, and hence, exercise training which effectively increases the CRF may be important for combating CVD. Previous studies indicate that exercise training of higher intensities may be superior to moderate intensity exercise training in improving CRF. Recent recommendations for physical activity suggest vigorous-intensity aerobic physical activity of 20 min on three days each week or moderate-intensity aerobic physical activity >30 min per day on five days each week, but these recommendations appear to be hard to fulfill for most people. Purpose: The purpose of this study was to test the hypothesis that substantially less exercise training, provided that the exercise training is vigorous, than currently recommended may be sufficient to increase VO2max. Methods: Twenty-four untrained men were randomized into high or low amount, of high intensity aerobic interval training consisting of either four (4-AIT, n=13) or one (1-AIT, n=11) 4-minutes intervals at 85-95% of maximal heart rate, 3 times per week over a 10-week period. VO2max exercise testing, blood sampling and body composition assessments were performed before and after both exercise training interventions. Results: VO2max expressed in direct proportion to body mass (mL·min-1·kg-1) increased by 13 % and 15 % (both p<0.001) after 1-AIT and 4-AIT, respectively. Body mass decreased by 1 % and 2% (both p<0.05) after 1-AIT and 4-AIT, respectively. BMI decreased for both groups (p<0.05), with a change of 1% and 2% after 1-AIT and 4-AIT, respectively.Conclusion: The results of the present study indicates that, in sedately subjects, 15 minutes of high intensity aerobic interval exercise training, three times per week, may be sufficient to give a robust improvement in VO2max, in sedately subjects.