Neurocardiologic and fitness changes in marathon skaters during interruption of training after their last competitive contest of the winter season

The authors studied nine male Dutch top marathon skaters during a one-month interruption of their training schedules after their last contest in the winter. Before and after this period a maximal exercise test was done, and at days 0, 4, 7, 14 and 28 neurocardiologic measurement sessions-heart rate (HR) and noninvasive baroreflex sensitivity (BRS), recumbent and tilt-were done. Interruption of training resulted in a significant and relevant decrease in the maximal oxygen uptake (from 65.7±5.8 to 61.6±4.7 ml O₂.kg^-1. min^-1; P=0.03), most likely to be associated with decreased competitive possibilities. A modest increase in resting heart rate (from 54.6±7.2 to 58.8±7.5 bpm) became not significant. Heart rate during 60° tilt increased considerably (from 70.3±6.1 to 80.1±9.1 bpm; P=0.01), possibly due to a decrease in blood volume and an increase in cardiopulmonary baroreflex gain. Baroreflex sensitivity decreased in the recumbent (from 13.3±5.4 to 9.8±3.8 ms/mmHg, P=0.04), but not in the 60° tilt position (from 6.7±2.0 to 6.0±2.5 ms/mmHg). The meaning of these neurocardiologic changes for athletic performance is unclear. The authors´ data show that detrimental changes in fitness, and neurocardiologic changes were measurable after a month of interruption of training, and will probably also be demonstrable in a larger group after 14 days