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Hyperpnea training attenuates peripheral chemosensitivity and improves cycling endurance
1 Exercise Physiology, Swiss Federal Institute of Technology and University
of Zurich, Zurich, Switzerland
2 John A. Burns School of Medicine, University of Hawaii, Honolulu, Hawaii,
USA
* Author for correspondence (e-mail: spengler{at}physiol.unizh.ch)
Accepted 16 September 2002
Well-trained endurance athletes frequently have a lower peripheral
chemoreceptor (pRc) sensitivity and a lower minute ventilation
(
E) during exercise compared to
untrained individuals. We speculated that the decreased pRc
response may be specifically associated with repeated exposure to the high
rates of ventilation occurring during exercise training. We therefore examined
the effect of respiratory muscle training (RMT; 20x 30 min sessions of
voluntary normocapnic hyperpnea) on the pRc sensitivity during
exercise and on cycling performance. RMT was chosen to achieve a high
E, similar to that of heavy exercise,
while avoiding the other accompanying effects of whole body exercise. 20
trained male cyclists were randomized into RMT (N=10) or control
(N=10) groups. Subjects' pRc response was assessed by a
modified Dejours O2 test (10-12 breaths of 100% O2,
repeated 4-6 times) during cycling exercise at 40% of the maximal work
capacity (
max). Cycling
performance was measured during a cycling test to exhaustion (85%
max). The RMT group
exhibited a significantly reduced pRc sensitivity (mean ±
S.D.) compared to the control group (-5.8±6.0% versus
0.1±4.6%, P<0.5). Cycling endurance improved significantly
after RMT in comparison to the control group (+3.26±4.98
versus -1.46±3.67 min, P<0.05). However, these
changes in pRc response were not significantly correlated with
exercise ventilation or cycling endurance time. We conclude that the high
levels of ventilation achieved during exercise, as simulated by RMT in this
study, appear to be accompanied by a reduction in pRc sensitivity;
however, the role of the pRc in the control of ventilation during
exercise seems to be minor.
Key words: respiratory muscle endurance training, carotid body, control of breathing, hyperpnea, exercise, human
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