NTRODUCTION: Traditionally, exercise performance has not been considered to be limited by ventilation or respiratory muscle function. However, prior reports suggests that respiratory muscle fatigue may influence exercise tolerance following prolonged submaximal exercise, as well as during short-term maximal exertion. Approaches such as inspiratory muscle warm-up (IMW) have emerged as plausible strategies for alleviating respiratory muscle fatigue and, arguably, enhancing exercise performance. While some studies have reported significant improvements, others have found no notable effects, suggesting that IMW may not significantly impact exercise tolerance. The underlying reasons for these discrepancies may stem, in part, from differences in the relative load of maximal inspiratory pressure (%MIP) prescribed during IMW. This hypothesis, however, remains unexplored. Therefore, we investigated the effects of different IMW loads on respiratory muscle fatigue, exercise tolerance, and physiological responses to incremental exercise in healthy adults. METHODS: Ten recreationally active men (mean age 22 ± 2 yrs; V̇O2max: 44 ± 4 mL·kg⁻¹·min⁻¹) attended the laboratory on four separate occasions. On Day 1, participants underwent a familiarisation with the procedures and measurement of MIP, a key indicator of inspiratory muscle strength. On Days 2-4, participants performed a ramp-incremental exercise test on a cycle ergometer to volitional exhaustion. Each test was preceded by an IMW, which involved two sets of 30 breaths using a Powerbreathe® device, with loads set at 15%, 40%, and 60% of MIP. Pulmonary gas exchange and ventilation data, along with near-infrared spectroscopy (NIRS)-derived muscle oxygenation parameters, were continuously monitored throughout the tests. Respiratory muscle fatigue was assessed by measuring MIP before IMW and 30 sec post-exercise tests. Perception of dyspnoea was assessed using a category, modified Borg scale. RESULTS: Respiratory muscle fatigue was significantly attenuated (-8%; P<0,05) following IMW at 40%, but not at 15% or 60% of MIP. However, perceived dyspnoea at both before (0.7 ± 0.3, 0.6 ± 0.2, and 0.6 ± 0.2) and after (9.0 ± 0.3, 9.2 ± 0.3, and 9.2 ± 0.3) the exercise test did not differ across the IMW loads (15%, 40%, and 60%, respectively) (P > 0.05). Similarly, no significant differences were observed in pulmonary gas exchange and ventilation, or NIRS-derived muscle oxygenation parameters between the different IMW loads during the exercise tests (P > 0.05). Exercise tolerance, as indicated by time to exhaustion (777 ± 79 s, 774 ± 71 s, and 775 ± 70 s), also remained comparable across the IMW loads (P > 0.05). CONCLUSION: Our findings suggest that IMW, regardless of the prescribed relative load, does not appreciably influence respiratory muscle fatigue, exercise tolerance, or physiological responses to incremental exercise in healthy adults. However, further research is needed to explore alternative IMW protocols and exercise modalities.
DOSE-DEPENDENT EFFECT OF INSPIRATORY MUSCLE WARM-UP ON RESPIRATORY MUSCLE FATIGUE, EXERCISE TOLERANCE AND PHYSIOLOGICAL RESPONSES TO INCREMENTAL EXERCISE
BALDARI C.;
2025-01-01
Abstract
NTRODUCTION: Traditionally, exercise performance has not been considered to be limited by ventilation or respiratory muscle function. However, prior reports suggests that respiratory muscle fatigue may influence exercise tolerance following prolonged submaximal exercise, as well as during short-term maximal exertion. Approaches such as inspiratory muscle warm-up (IMW) have emerged as plausible strategies for alleviating respiratory muscle fatigue and, arguably, enhancing exercise performance. While some studies have reported significant improvements, others have found no notable effects, suggesting that IMW may not significantly impact exercise tolerance. The underlying reasons for these discrepancies may stem, in part, from differences in the relative load of maximal inspiratory pressure (%MIP) prescribed during IMW. This hypothesis, however, remains unexplored. Therefore, we investigated the effects of different IMW loads on respiratory muscle fatigue, exercise tolerance, and physiological responses to incremental exercise in healthy adults. METHODS: Ten recreationally active men (mean age 22 ± 2 yrs; V̇O2max: 44 ± 4 mL·kg⁻¹·min⁻¹) attended the laboratory on four separate occasions. On Day 1, participants underwent a familiarisation with the procedures and measurement of MIP, a key indicator of inspiratory muscle strength. On Days 2-4, participants performed a ramp-incremental exercise test on a cycle ergometer to volitional exhaustion. Each test was preceded by an IMW, which involved two sets of 30 breaths using a Powerbreathe® device, with loads set at 15%, 40%, and 60% of MIP. Pulmonary gas exchange and ventilation data, along with near-infrared spectroscopy (NIRS)-derived muscle oxygenation parameters, were continuously monitored throughout the tests. Respiratory muscle fatigue was assessed by measuring MIP before IMW and 30 sec post-exercise tests. Perception of dyspnoea was assessed using a category, modified Borg scale. RESULTS: Respiratory muscle fatigue was significantly attenuated (-8%; P<0,05) following IMW at 40%, but not at 15% or 60% of MIP. However, perceived dyspnoea at both before (0.7 ± 0.3, 0.6 ± 0.2, and 0.6 ± 0.2) and after (9.0 ± 0.3, 9.2 ± 0.3, and 9.2 ± 0.3) the exercise test did not differ across the IMW loads (15%, 40%, and 60%, respectively) (P > 0.05). Similarly, no significant differences were observed in pulmonary gas exchange and ventilation, or NIRS-derived muscle oxygenation parameters between the different IMW loads during the exercise tests (P > 0.05). Exercise tolerance, as indicated by time to exhaustion (777 ± 79 s, 774 ± 71 s, and 775 ± 70 s), also remained comparable across the IMW loads (P > 0.05). CONCLUSION: Our findings suggest that IMW, regardless of the prescribed relative load, does not appreciably influence respiratory muscle fatigue, exercise tolerance, or physiological responses to incremental exercise in healthy adults. However, further research is needed to explore alternative IMW protocols and exercise modalities.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
