Overtraining syndrome (OTS) is a major concern among endurance athletes and is a leading cause in preventing them to perform for long periods. Intermittent exposure to hypoxia has been shown to be an effective way of improving performance without exercising. Aim of this pilot study was to evaluate intermittent hypoxia-hyperoxia training combined with light exercise as an intervention to facilitate athletes with OTS to restore their usual performance level. Thirty-four track and field athletes were recruited: 15 athletes with OTS volunteered to participate and undertook a conditioning programme consisting of repeated exposures to hypoxia (O2 at 10%) and hyperoxia (O2 at 30%) (6-8 cycles, total time 45 min-1 h), three times a week, delivered 1·5-2 h after a low-intensity exercise session (2 bouts of 30 min, running at 50% of VO2max with 10 min rest between bouts) over 4 weeks. Nineteen healthy track and field athletes volunteered to participate as a control group and followed their usual training schedule. Measurements before and after the intervention included exercise capacity, analysis of heart rate variability and hematological parameters. In athletes with OTS, a 4-week light exercise combined with intermittent hypoxia-hyperoxia training improved exercise performance (191·9 ± 26·9 W versus 170·8 ± 44·8 W in exercise capacity test, P = 0·01). Heart rate variability analysis revealed an improved sympatho-parasympathetic index (low frequency/high frequency ratio, 8·01 ± 7·51 before and 1·45 ± 1·71 after, P = 0·007). Hematological parameters were unchanged. Our pilot study showed that intermittent hypoxia-hyperoxia training and low-intensity exercise can facilitate functional recovery among athletes with OTS in a relatively short time.
Keywords: athletic performance; cardiac autonomic control; exercise tolerance; heart rate variability; intermittent hypoxic training; recovery of function.
© 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.