Putative Role of Respiratory Muscle Training to Improve Endurance Performance in Hypoxia: A Review (original) (raw)

Respiratory muscle endurance training: effect on normoxic and hypoxic exercise performance

European Journal of Applied Physiology, 2010

The aim of this study was to investigate the effect of respiratory muscle endurance training on endurance exercise performance in normoxic and hypoxic conditions. Eighteen healthy males were stratified for age and aerobic capacity; and randomly assigned either to the respiratory muscle endurance training (RMT = 9) or to the control training group (CON = 9). Both groups trained on a cycle-ergometer 1 h day−1, 5 days per week for a period of 4 weeks at an intensity corresponding to 50% of peak power output. Additionally, the RMT group performed a 30-min specific endurance training of respiratory muscles (isocapnic hyperpnea) prior to the cycle ergometry. Pre, Mid, Post and 10 days after the end of training period, subjects conducted pulmonary function tests (PFTs), maximal aerobic tests in normoxia ( \( {\dot{V}} \) O2maxNOR), and in hypoxia ( \( {\dot{V}} \) O2maxHYPO; FIO2 = 0.12); and constant-load tests at 80% of \( {\dot{V}} \) O2maxNOR in normoxia (CLTNOR), and in hypoxia (CLTHYPO). Both groups enhanced \( {\dot{V}} \) O2maxNOR (CON: +13.5%; RMT: +13.4%), but only the RMT group improved \( {\dot{V}} \) O2maxHYPO Post training (CON: −6.5%; RMT: +14.2%). Post training, the CON group increased peak power output, whereas the RMT group had higher values of maximum ventilation. Both groups increased CLTNOR duration (CON: +79.9%; RMT: +116.6%), but only the RMT group maintained a significantly higher CLTNOR 10 days after training (CON: +56.7%; RMT: +91.3%). CLTHYPO remained unchanged in both groups. Therefore, the respiratory muscle endurance training combined with cycle ergometer training enhanced aerobic capacity in hypoxia above the control values, but did not in normoxia. Moreover, no additional effect was obtained during constant-load exercise.

Exercise training in chronic hypoxia has no effect on ventilatory muscle function in humans

Respiration Physiology, 1998

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 9 8.9 vs. 106.998.6 cmH 2 O, P= 0.163), peak inspiratory flow (9.89 0.41 vs. 10.29 0.55 L · sec − 1, P= 0.172) and the maximum volitional volume in 12 sec (43.9 9 2.4 vs. 45.6 9 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 (177.49 7.9 vs. 165.49 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.