Training mode does not affect orthostatic tolerance in chronically exercising subjects

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• 作者：Warren D. Franke ; Kimberly K. Mills ; Kichang Lee and Juliane P. Hernandez
• 关键词：Lower body negative pressure Presyncope Baroreceptor
• 刊名：European Journal of Applied Physiology
• 出版年：2003
• 出版时间：May 2003
• 年：2003
• 卷：89
• 期：3-4
• 页码：263-270
• 全文大小：280 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Biomedicine
  Human Physiology
  Occupational and Industrial Medicine
  Sports Medicine
  
• 出版者：Springer Berlin / Heidelberg
• ISSN：1439-6327

文摘

This study tested the hypotheses that trained swimmers would have greater orthostatic tolerance than runners and, if present, it would be due to differences in their autonomic and hemodynamic responses to graded central hypovolemia. Twenty intercollegiate male athletes [11 runners and 9 swimmers; V˙O_2max =70.0 (1.6) vs 69.5 (2.6) ml·kg?1·min?1, respectively] underwent graded lower body negative pressure (LBNP) to presyncope. The swimmers were heavier [80.5 (1.9) vs 70.3 (1.9) kg, P<0.05], with larger resting cardiac [4.44 (0.29) vs 3.68 (0.18) l·min?1·m?2] and total peripheral conductance [0.056 (0.04) vs 0.044 (0.02) units·m?2] indices. Neither spontaneous cardiac baroreflex sensitivity (sequence method) nor heart rate variability (spectral analysis) differed significantly between groups at rest. LBNP tolerance did not differ between groups, with an index value of 51 (2) kPa·min for the runners and 54 (4) kPa·min for the swimmers [383 (16) vs 402 (32) mmHg·min] , although the swimmers had larger declines in pulse pressure and tended (P=0.078) to have larger declines in total peripheral conductance index in the last completed stage of LBNP. These responses did not differ between groups in the last 2 min of LBNP. Neither the heart rate, mean arterial pressure nor forearm vascular conductance responses differed between groups throughout. Changes in heart rate variability indices did not differ significantly between groups, with similar declines in the high frequency component and increases in the low frequency/high frequency ratio. These data suggest that swim training does not lead to greater orthostatic tolerance than run training, and responses to maximal LBNP do not differ between swimmers and runners. Moreover, neither heart rate nor the autonomic modulation of the heart rate response to LBNP are affected by training modality.