Low- and High-Volume of Intensive Endurance Training Significantly Improves Maximal Oxygen Uptake after 10- Weeks of Training in Healthy Men

Regular exercise training improves maximal oxygen uptake (VO2max), but the optimal intensity and volume necessary to obtain maximal benefit remains to be defined. A growing body of evidence suggests that exercise training with low-volume but high-intensity may be a time-efficient means to achieve health benefits. In the present study, we measured changes in VO2max and traditional cardiovascular risk factors after a 10 wk. training protocol that involved three weekly high-intensity interval sessions. One group followed a protocol which consisted of 464 min at 90 % of maximal heart rate (HRmax) interspersed with 3 min active recovery at 70 % HRmax (4-AIT), the other group performed a single bout protocol that consisted of 164 min at 90 % HRmax (1-AIT). Twenty-six inactive but otherwise healthy overweight men (BMI: 25–30, age: 35– 45 y) were randomized to either 1-AIT (n = 11) or 4-AIT (n = 13). After training, VO2max increased by 10% (,5.0 mL?kg21?min21) and 13 % (,6.5 mL?kg21?min21) after 1-AIT and 4-AIT, respectively (group difference, p = 0.08). Oxygen cost during running at a sub-maximal workload was reduced by 14 % and 13 % after 1-AIT and 4-AIT, respectively. Systolic blood pressure decreased by 7.1 and 2.6 mmHg after 1-AIT and 4-AIT respectively, while diastolic pressure decreased by 7.7 and 6.1 mmHg (group difference, p = 0.84). Both groups had a similar,5 % decrease in fasting glucose. Body fat, total cholesterol, LDL-cholesterol, and ox-LDL cholesterol only were significantly reduced after 4-AIT. Our data suggest that a single bout of AIT performed three times per week may be a time-efficient strategy to improve VO2max an