Hatle, H., Stobakk. P. K., Bronstad, E., Stolen, T., Tjonna, A. E., Molmen, H. E., Ingul, C. B., Wisloff, U., & Rognmo, O. (2009). Effects of frequency of exercise for improving aerobic capacity: Training and de-training. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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"Aerobic exercise performed as interval training is an effective way of improving maximal aerobic capacity (VO2max). We have previously shown that high-intensity exercise performed 2-3 times per week is superior to moderate exercise for improving VO2max when total exercise volume is equalized. This is valid both within highly trained individuals as well as in different patient groups." This study investigated the rate of adaptation of VO2max in young, healthy individuals (N = 19) performing exercise at either high frequency or moderate training frequency. It was hypothesized that improvements of VO2max could be achieved to the same extent when exercising at high frequency compared to moderate frequency. Ss completed 24 exercise sessions at either three times per week for eight weeks, or eight times per week for three weeks. Training was uphill treadmill running using heart rate monitors. VO2max was measured initially and after every eighth exercise session. During the de-training period, VO2max was measured 4, 14, and 24 days post-exercise, and thereafter every second week over two months.

The moderate frequency group significantly increased VO2max by ~6.0 ml/kg/min and the high frequency group by ~4.1 ml/kg/min. After correction for baseline value, no differences between the groups for VO2max change were found. The moderate frequency group reached the highest measured VO2max value four days post-training while the high frequency group reached the peak value 14 days post-training. This elevation was sustained 24 days post-training in the high frequency group, but the moderate frequency group declined VO2max compared to peak level during the same period.

Implication. Improvements in VO2max after high-intensity aerobic interval training could be accomplished in reduced time with high frequency training when compared to normal frequency training. VO2max may increase further after ending a high-intensive, high-frequency training program. That over-compensation may be sustained for over three weeks without training. [This study shows a notable change in VO2max but it should not be inferred that performance will change similarly.]

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