Frequency and duration of interval training programs and changes in aerobic power

Area of Science:

• Exercise Physiology
• Cardiovascular Adaptation
• Sports Science

Background:

• Maximal aerobic power (VO2max) is a key indicator of cardiorespiratory fitness.
• Interval training is a common method to improve VO2max.
• Optimal training frequency and duration for VO2max improvements remain areas of investigation.

Purpose of the Study:

• To compare the effects of different interval training frequencies (2 vs. 4 days/wk) and durations (7 vs. 13 wks) on VO2max.
• To assess the impact of training frequency and duration on maximal and submaximal heart rate.
• To determine the influence of training parameters on the determinants of VO2max.

Main Methods:

• Sixty-nine healthy college males participated in the study.
• Subjects underwent 7- or 13-week interval training programs at either 2 or 4 days/wk.
• VO2max was measured using a bicycle ergometer and open-circuit spirometry.
• Maximal and submaximal heart rates were monitored via ECG.

Main Results:

• VO2max significantly increased post-training, irrespective of training frequency or duration.
• A trend for greater VO2max gains was observed with longer (13-wk) training.
• Maximal heart rate decreased significantly post-training, independent of training parameters.
• Submaximal heart rate decreased significantly, with greater reductions seen in more frequent and longer training groups.

Conclusions:

• Training frequency and duration do not appear to be critical factors for improving VO2max.
• Maximal stroke volume and maximal avO2 difference, key VO2max determinants, are not dependent on training frequency or duration.
• Increased training frequency and duration offer benefits in reducing circulatory stress during submaximal exercise.