Respiration Physiology 112 (1998) 195 – 202 Exercise training in chronic hypoxia has no effect on ventilatory muscle function in humans Rickey G. Thomas a , Paul C. LaStayo a , Hans Hoppeler b , Roland Favier c , Guido Ferretti d , Bengt Kayser d , Dominique Desplanches c , Hilde Spielvogel e , Stan L. Lindstedt a, * a Physiology and Functional Morphology Group, Department of Biological Sciences, Northern Arizona Uniersity, Flagstaff, AZ 86011 -5640, USA b Anatomisches Institut, Uniersita ¨t Bern, Bu ¨hlstrasse, CH-3000 Bern 9, Switzerland c URA 1341 CNRS, Laboratoire de Physiologie, Uniersite ´ Claude Barnard, 69373 Lyon, France d De ´partement de Physiologie, Centre Me ´dical Uniersitaire, Gene ` e 4, Switzerland e Instituto Boliiano de Biologı ´a de Altura, Uniersidad Mayor de San Andre ´s, Casilla 717, La Paz, Boliia Accepted 9 February 1998 Abstract At the highest altitude, aerobic work is limited by environmental oxygen availability. We therefore reasoned that the hyperpnea associated with endurance training at altitude should provide a strong stimulus for adaptation of the ventilatory muscles. We measured peak inspiratory muscle pressure-flow characteristics (inspiring through graded resistors) and maximum sustainable ventilation capacity in ten permanent residents of La Paz, Bolivia (3600 m) prior to and immediately following 6 weeks of incremental endurance training. Additionally, eight local residents did no training and functioned as controls for the capacity test. While V O 2 max measured in hypoxia increased by 19% (Favier et al., 1995b. J. Appl Physiol. 78, 2286 – 2293.), none of the tested ventilatory variables showed significant changes. The values for the group mean slopes of maximum inspiratory pressure-flow pairs ( -10.5 vs. -9.8 cm H 2 O·sec·L -1 , P =0.301; before versus after training, respectively), maximum inspiratory pressure (112.1 8.9 vs. 106.9 8.6 cmH 2 O, P =0.163), peak inspiratory flow (9.8 0.41 vs. 10.2 0.55 L · sec -1, P =0.172) and the maximum volitional volume in 12 sec (43.9 2.4 vs. 45.6 2.4 L in 12 sec, P =0.133) were unchanged with exercise training. Likewise, maximal sustainable minute volume was not different between post-training and control subjects (177.4 7.9 vs. 165.4 8.4 L·min -1 , P =0.141). These data support the concept that endurance training fails to elicit functional adaptations in ventilatory muscles in humans, even when exercise is done in hypoxia. © 1998 Elsevier Science B.V. All rights reserved. * Corresponding author: Tel.: +1 520 5237524; fax: +1 520 5237500; e-mail: stan.lindstedt@nau.edu 0034-5687/98/$19.00 © 1998 Elsevier Science B.V. All rights reserved. PII S0034-5687(98)00017-6