Breil, F. A., Weber, S. N., Koller, S., Hoppeler, H., & Vogt, M. (2009). High intensity shock microcycles: An efficient method for improving VO2max in junior alpine skiers. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

This study investigated the effect of an 11-day high-intensity shock microcycle on endurance and jump performance in junior alpine skiers (M = 16; F = 6). Ss were formed into a high-intensity interval training group (N = 13) or a control training group (N = 8). The high-intensity group performed 15 high-intensity training sessions (12 on a cycle ergometer, 3 on an obstacle course) over 11 days. Each session consisted of 4×4 minutes at 90-95% of the individual maximal heart rate (HRmax), separated by 3-minute recovery periods. The control group continued normal mixed training including endurance and strength sessions. Before and 24 hours and seven days after the training period, anthropometric data were gathered and ramp tests to exhaustion on a cycle ergometer were performed to determine HRmax, VO2max, peak power output, and the first and second ventilatory thresholds. At the same time-points, countermovement and squat jumps were performed on a force plate.

Body mass and fat-free mass were reduced only in the high-intensity training group. Seven days post-intervention, the high-intensity group significantly improved VO2max by 6.0% and peak power output by 4.4%. The control group showed slight but nonsignificant improvements in VO2max (+3.0%) and peak power output (+2.0%). Power output at the second ventilatory threshold increased in the high-intensity group by 9.6%, but not in the control group. Jump height was unchanged in both groups. In the high-intensity group, the described functional improvements were already present but to a lesser extent in the post 24-hours measurements.

Implication. High-intensity interval block training might be a very time efficient way to improve VO2max, peak power output, and power output at the second ventilatory threshold in junior alpine skiers. The authors reason that accumulated fatigue of such an intense training cycle seems to delay the development of the functional adaptations and therefore, athletes and coaches should plan rest-days to ensure adequate recovery and maximal training effect. [However, this simply could be a demonstration that particular types of training can change physiological measures but not affect performance. That would be particularly so if the measures were unrelated to the actual sporting performance. Unless studies that show changes in physiological measures also demonstrate concomitant alterations in performance, one should not infer that the training and/or physiological measures are related to or beneficial for specific performances.]

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