Determining the Optimal Interval Exercise Intensity Dose for Improving Exercise Performance

Abstract

Short duration interval training is a time-efficient exercise strategy that can improve fitness through changes in metabolic, cardiovascular and performance related variables. Studies have examined the positive effects of maximal intensity exercise (≥100% VO2max) on metabolic and performance variables in recreationally active individuals and trained athletes. The intensity of interval training required to cause improvements in aerobic fitness is unknown. This study will look at the performance related adaptations that occur with three different exercise intensities of interval training matched in terms of duration, frequency and type of exercise. Sixteen recreationally active individuals, both males (n=9, age = 23.3±3.3, VO2max = 44.2±6.5) and females (n=6, age = 21.5±0.7, VO2max = 39.7±5.4) were randomly assigned to one of three groups who trained using intervals at 120% VO2max (n=5), 90% VO2max (n=4) or 65% VO2max (n=7). The participants performed 14 days of training spread over 4 weeks that consisted of 8-12 repeats of 1-minute cycling at the prescribed intensity with 1-minute active recovery between intervals. Training increased time to fatigue in the 90% VO2max and 120% VO2max group however not in the 65% VO2max group. The changes in VO2max before and after training were significant in the 90% VO2max group and the 120% VO2max group, however not between the 120% VO2max and 90% VO2max group (p≤0.05). Interval training at 90% and 120% VO2max stimulates analogous improvements in fitness. These results may be important for diseased or sedentary populations where very high-intensity and long duration exercise may not be well tolerated.