Influence of environmental temperature on exercise-induced inspiratory muscle fatigue

Abstract

Exercise in the heat has detrimental effects on circulation that might negatively influence endurance performance. If blood is diverted away from the inspiratory muscles to the skin during exercise in the heat, exercise-induced inspiratory muscle fatigue might be exacerbated. Thus, we hypothesised that prolonged heavy endurance exercise in the heat would impair exercise performance and exacerbate inspiratory muscle fatigue compared to exercise in a thermo-neutral environment. Using a crossover design, seven male endurance trained subjects [mean (SEM) maximum oxygen uptake = 62.2 (1.5) ml x kg(-1) x min(-1)] were assigned at random to either a group that exercised in the heat at an ambient temperature of 35 degrees C (H) or a group that exercised in the cool at 15 degrees C (C). Maximum inspiratory mouth pressure at zero flow (P(0)), pressure normalised maximum relaxation rate (MRR/ P(0)), time constant for the pressure decay (tau), and maximum inspiratory flow at 30% P(0) (V(30)) were assessed immediately before and reassessed within 2, 30, and 60 min of completing a pre-loaded time trial [40 min at 65% peak power, plus approximately 30 min time trial] on a cycle ergometer. Group H completed the time trial 432 (135) s slower than group C [2285 (180) vs 1852 (122) s, respectively; Delta=24 (8)%, P=0.0094]. Repeat measurements within 2 min post-exercise revealed significant declines in P(0), MRR/ P(0), tau, and V(30) from baseline values, but no between-group differences were observed. In conclusion, heavy sustained exercise in the heat impaired subsequent time-trial performance but did not exacerbate inspiratory muscle fatigue in endurance-trained subjects.

Effects of Ambient Temperature on Physiological Responses to Incremental Exercise Test

“…The highest peak level of minute ventilation (VEmax) was observed in the test performed in temperature of 37˚C mainly due to increased respiratory rate without increase in tidal volume. These changes are similar to those of previous laboratory (Tyka et al, 2009) and indicate that high temperature during incremental exercise test, as well as during prolonged heavy endurance exercise, does not restrict respiration and oxygen intake (Romer et al, 2004).…”

Effect of lower body compression garments on submaximal and maximal running performance in cold (10°C) and hot (32°C) environments

“…As a result of the increase in cardiovascular workload, previous studies showed that the exercise time to exhaustion was attenuated (Galloway and Maughan 1997;Romer et al 2004). Thus, it was hypothesized that the time to exhaustion would decrease at 32°C with compression garments.…”

Evaluation of Fatigue of Respiratory and Lower Limb Muscles During Prolonged Aerobic Exercise

“…The mean power frequency (MPF) of the EMG is an alternative measure of fatigue, at the frequency domain (Rochester, 1988;Ratnovsky et al, 2008). The MPF values were calculated for each muscle per each subject with and without a backpack load.…”

“…Several studies were concerned with the effectiveness of respiratory muscle training (RMT) and its contribution to exercise performance and role in exercise limitation (Markov et al, 2001;Stuessi et al, 2001;, Sheel, 2002;Holm et al, 2004;Romer et al, 2004;Verges et al, 2006). In these studies it was demonstrated that the respiratory muscles, as other skeletal muscles, specifically adapt to RMT and to whole body exercise training in relation to parameters such as pulmonary function, respiratory muscle endurance, maximal strength and exercise endurance time.…”