FREDERIKS, J., C. A. SWENNE, A. V. G. BRUSCHKE, E. T. VAN DER VELDE, A. C. MAAN, B. J. TENVOORDE, M. G. C. VANROOIJEN, W. L. MOSTERD, and P. SCHIERECK. Correlated neurocardiologic and fitness changes in athletes interrupting training. Med. Sci. Sports Exerc., Vol. 32, No. 3, pp. 571–575, 2000.
We studied nine male Dutch top marathon skaters during a 1-month interruption of their training schedules after their last contest in the winter to investigate a possible decline in baroreflex sensitivity.
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 and noninvasive baroreflex sensitivity, recumbent and tilt —were performed.
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 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° 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 cardiopulmonary baroreflex gain. Arterial baroreflex sensitivity decreased significantly 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° 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).
In summary, our data show that correlated detrimental changes in fitness and baroreflex sensitivity are measurable in these athletes after a month of interruption of training.
Cardiology Department, Leiden University Medical Center, Leiden, THE NETHERLANDS; Foundation for ECG Analysis Leiden (SEAL), Leiden, THE NETHERLANDS; Department of Medical Physics and Informatics, Free University, Amsterdam, THE NETHERLANDS; and Department of Medical Physiology and Sports Medicine, Utrecht University, Utrecht, THE NETHERLANDS
Submitted for publication March 1998.
Accepted for publication September 1998.
Address for correspondence: Cees A. Swenne, Ph.D., Cardiology Department, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands. E-mail: c.a.swenne@Lumc.nL.