Rodriguez, F. A., Iglesias, X., Feriche, B., Calderon, C., Abalos, X., Vazquez, J., Barrero, A., Rodriguez, L., Hynynen, E., & Levine, B. D. (2012). Effects of altitude training on heart rate variability in orthostatic test in elite swimmers. Presentation 1562 at the 59th Annual Meeting of the American College of Sports Medicine, San Francisco, California; May 29-June 2, 2012.

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This study investigated the effects of three weeks of moderate altitude training on heart rate variability in elite swimmers (M = 4; F = 5). A control group (M = 4; F = 7) lived and trained at sea-level. The experimental group lived and trained for three weeks at Sierra Nevada, Spain (2,320 m). RR-intervals were recorded every morning in supine (8-min) and orthostatic (6-min) positions with beat-by-beat heart monitors. Breathing was paced at 12 breaths per minute. Recordings were taken during the three-week intervention period and one week before and after. Heart rate variability was analyzed from the last five-minute period in both positions. TRIMPs of every training session were calculated to estimate training load. Heart rate variability was averaged over every week and presented as relative percentage changes.

Training load was similar in both groups during the three-week intervention but was lower during the week after in the altitude group when compared to the sea-level group. Heart rate variability increased in the sea-level group and decreased in the altitude group during the intervention.

Implication. The lower heart rate variability in the altitude group than in the sea-level group suggests that the physiological stress of training at moderate altitude leads to parasympathetic withdrawal and possibly increased sympathetic activity even after a night's rest. These changes in autonomic modulation appear to last longer than for the first week after altitude training camp.

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