Key result
Inspiratory muscle fatigue cuts time to exhaustion ~9% vs placebo and decreases limb muscle oxygenation.
Why the study?
Inspiratory muscle fatigue may impair blood flow to active limb muscles via respiratory muscle metaboreflex, affecting high-intensity exercise performance and muscle oxygenation.
Does inspiratory muscle fatigue reduce high-intensity exercise performance and muscle tissue oxygenation in healthy males?
RCT (n=9)
Single-blind
Randomized crossover
No
Does inspiratory muscle fatigue reduce high-intensity exercise performance and muscle tissue oxygenation in healthy males?
Effect estimate: 8.5% reduction
Absolute Event Rate: 244% vs 268%
p-value: p=0.004
Inspiratory muscle fatigue impairs oxygen delivery to active limb muscles and significantly decreases high-intensity exercise performance in healthy males.
Small study in healthy males offers no basis to alter training; leaves open metaboreflex effects on performance and oxygenation.
It has been suggested that inspiratory muscles fatigue impairing blood flow to the active limb muscle via respiratory muscle metaboreflex. The purpose of this study was to investigate the effects of inspiratory muscle fatigue on exercise performance and muscle tissue oxygenation in high-intensity exercise takes about 3.5~5min. Eleven healthy males subjects performed two conditions of constant-load exercise to exhaustion (TTE) on a cycle ergometer at 100% of maximal oxygen uptake. The two conditions—inspiratory muscle fatiguing (IMF) and non-fatiguing (PLA) —which had different intensity inspiratory resistance breathing (IRB) were performed before exercise. Muscle tissue oxygenations were measured by deoxyhemogrobin (HHb), oxygen saturation index (StO2) from right vastus lateralis during TTE. All data were analyzed from nine subjects whose inspiratory muscle were fatigued by IRB in IMF. Results: TTE was significantly shorter in IMF compare to PLA (244±31s vs. 268±38s, p<0.05). HHb was significantly higher and StO2 was significantly lower in IMF than in PLA (p<0.05). Conclusion: High-intensity exercise completed in 3.5~5 minutes, it was suggested that inspiratory muscle fatigue reduced the oxygen deriver to active limb muscle, resulting in decrease exercise performance. Improving function of inspiratory muscles, such as in inspiratory muscle training, may improve oxygenation of the active limb muscle and enhance exercise performance.
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Koizumi et al. (2022) conducted an RCT in Healthy (n=9). Inspiratory muscle fatiguing (IMF) vs. Placebo (15% of maximal inspiratory pressure) was evaluated on Time to exhaustion (TTE) (8.5% reduction, p=0.004). Inspiratory muscle fatigue significantly reduced time to exhaustion during high-intensity exercise compared to placebo (244 vs 268 seconds, p=0.004) and decreased active limb muscle oxygenation.
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