Increased fatigue resistance of respiratory muscles during exercise after respiratory muscle endurance training

Abstract

Respiratory muscle fatigue develops during exhaustive exercise and can limit exercise performance. Respiratory muscle training, in turn, can increase exercise performance. We investigated whether respiratory muscle endurance training (RMT) reduces exercise-induced inspiratory and expiratory muscle fatigue. Twenty-one healthy, male volunteers performed twenty 30-min sessions of either normocapnic hyperpnoea (n = 13) or sham training (CON, n = 8) over 4-5 wk. Before and after training, subjects performed a constant-load cycling test at 85% maximal power output to exhaustion (PRE(EXH), POST(EXH)). A further posttraining test was stopped at the pretraining duration (POST(ISO)) i.e., isotime. Before and after cycling, transdiaphragmatic pressure was measured during cervical magnetic stimulation to assess diaphragm contractility, and gastric pressure was measured during thoracic magnetic stimulation to assess abdominal muscle contractility. Overall, RMT did not reduce respiratory muscle fatigue. However, in subjects who developed >10% of diaphragm or abdominal muscle fatigue in PRE(EXH), fatigue was significantly reduced after RMT in POST(ISO) (inspiratory: -17 +/- 6% vs. -9 +/- 10%, P = 0.038, n = 9; abdominal: -19 +/- 10% vs. -11 +/- 11%, P = 0.038, n = 9), while sham training had no significant effect. Similarly, cycling endurance in POST(EXH) did not improve after RMT (P = 0.071), while a significant improvement was seen in the subgroup with >10% of diaphragm fatigue after PRE(EXH) (P = 0.017), but not in the sham training group (P = 0.674). However, changes in cycling endurance did not correlate with changes in respiratory muscle fatigue. In conclusion, RMT decreased the development of respiratory muscle fatigue during intensive exercise, but this change did not seem to improve cycling endurance.

Special training of inspiratory muscles in fitness activities and exercise capacity in young women

“…cycle endurance at the anaerobic threshold (77% VO 2 max) was improved from 22.8 min to 31.5 min, while VO 2 max and the anaerobic threshold remained essentially the same [7]. The effects of IMT with flow resistance devices in cycle endurance athletes were connected with improving the time of sustained exercise intensity at the anaerobic threshold, while VO 2 max and the anaerobic threshold (VO 2 in % VO 2 max) remained basically unchanged [7,8,31]. Some studies show that IMT leads to an increase of aerobic power in hypoxic situations only [3].…”

“…In healthy people and in athletes, the inability to sustain high levels of ventilation can restrict maximal aerobic capacity [7,12,31]. It has been shown that IMT without the addition of systemic exercise may result in quantitative outcomes [9,10,17,32].…”

Exercise-induced respiratory muscle fatigue: implications for performance

“…Studies that have specifically trained the respiratory muscles have reported either an improvement (16,17,28,33,78,84,119,124,131) or no change (25,29,38,57,92,117,140) in whole body exercise tolerance. A concern with all of these studies, however, is that endurance performance was evaluated using fixed work-rate tasks sustained to the limit of tolerance.…”

“…The ergogenic effect could be due to relief of respiratory muscle fatigue (105,131) or limb muscle fatigue (81), perhaps by attenuation of the respiratory muscle metaboreflex (142). However, the perceptual benefit obtained through relieving the discomfort associated with high levels of respiratory muscle work may also be responsible for at least some of the improvement in exercise performance (82).…”

Compartmental chest wall volume changes during volitional hyperpnoea with constant tidal volume in healthy individuals

“…Respiratory muscle training can reduce or delay the development of respiratory muscle fatigue Verges et al, 2007;Verges et al, 2009). This in turn may prevent the development of rapid and shallow breathing as shown in some (Spengler et al, 1999;Volianitis et al, 2001;Amonette and Dupler 2002;Wylegala et al, 2007;Esposito et al, 2010) but not in other (Kohl et al, 1997;Stuessi et al, 2001;Volianitis et al, 2001;McMahon et al, 2002;Holm et al, 2004;Griffiths and McConnell 2007;Verges et al, 2007;Brown et al, 2010;Ray et al, 2010) studies.…”