Correlated neurocardiologic and fitness changes in athletes interrupting training

Purpose: We studied nine male Dutch top marathon skaters during a 1-month i nterruption of their training schedules after their last contest in the win ter to investigate a possible decline in baroreflex sensitivity. Methods: B efore and after this period, a maximal exercise test was done, and at days 0, 4, 7, 14, and 28 neurocardiologic measurement sessions-heart rate and no ninvasive baroreflex sensitivity, recumbent and tilt-were performed. Result s: 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 O-2. kg (-1).min(-1); P = 0.03), most likely associated with decreased competitive possibilities. Resting heart rate modestly increased (from 54.6 +/- 7.2 to 58.8 +/- 7.5 bpm), however, not significantly. Heart rate during 60 degrees tilt increased considerably (from 70.1 +/- 6.1 to 80.1 +/- 9.1 bpm; P = 0. 01), possibly due to a decrease in blood volume and an increase in cardiopu lmonary baroreflex gain. Arterial baroreflex sensitivity decreased signific antly in the recumbent (from 13.3 +/- 5.4 to 9.8 +/- 3.8 ms.mm Hg-1, P = 0. 04), but not in the 60 degrees tilt position (from 6.7 +/- 2.0 to 6.0 +/- 2 .5 ms mm Hg-1). The relative decrease in baroreflex sensitivity and maximal oxygen uptake correlated significantly (r = 0.71, P = 0.02). Conclusions:I n summary, our data show that correlated detrimental changes in fitness and baroreflex sensitivity are measurable in these athletes after a month of i nterruption of training.