The Impact of Interval Intensity in Overweight Young Men
Boyd, John Colin
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Considering the increasing global prevalence of overweight and obesity and their propensity for disease, this study was undertaken in an attempt to optimize exercise prescription for this at-risk group by determining if the benefits associated with interval training occur in an intensity dependent manner. 19 sedentary, overweight males (Age: 22.7 ± 3.9 yrs, BMI: 31.4 ± 2.6 kg/m2, WC: 106.5 ± 6.6 cm) performed interval training for three weeks at either 70% or 100% of their peak work rate on a cycle ergometer. Aerobic capacity measurements, time to completion trials, muscle biopsies, and fasted blood samples were all performed pre and post training. Analyses of aerobic capacity and exercise performance demonstrate greater improvements made in the 100% compared to the 70% group, while measures of skeletal muscle oxidative capacity indicate equivalent changes between groups. Taking into account the similar increases in mitochondrial content in both groups and understanding the influence of both oxygen supply and demand in determining maximal oxygen consumption, the greater increases in aerobic capacity achieved by the 100% group may be the result of enhanced cardiovascular adaptations. These findings suggest that some of the health benefits associated with interval exercise may be intensity dependent. Therefore, there may be additional benefit to exercise at higher intensities.