Effect of Inspiratory Muscle-Loaded Exercise Training on Ventilatory Response and Intercostal Muscle Deoxygenation During Incremental Cycling Exercise

• Published in: Research Quarterly for Exercise and Sport Vol. 96; no. 1; pp. 62 - 74
• Main Authors: Koike, Jun, Ogawa, Takeshi
• Format: Journal Article
• Language: English
• Published: United States Routledge 02.01.2025; Informa UK Limited
• Subjects: Adult; Bicycling - physiology; Breathing Exercises - methods; Exercise - physiology; Exercise Test; Exercise training; Humans; inspiratory muscle training; Intercostal Muscles - metabolism; Intercostal Muscles - physiology; Male; Muscle Strength - physiology; near-infrared spectroscopy; Oxygen Consumption - physiology; Physical Endurance - physiology; Pulmonary Ventilation - physiology; respiratory muscle; Respiratory Muscles - physiology; Tidal Volume; Young Adult; inspiratory muscle training; respiratory muscle; near-infrared spectroscopy; Exercise training
• ISSN: 0270-1367; 2168-3824; 2168-3824
• DOI: 10.1080/02701367.2024.2365291

Purpose: This study evaluated the effects of exercise training (ET) and inspiratory muscle-loaded exercise training (IMLET) on ventilatory response and intercostal muscle deoxygenation levels during incremental cycling exercise. Methods: Twenty-one male participants were randomly divided into IMLET (n = 10) or ET (n = 11) groups. All participants underwent a 4-week cycling exercise training at 60% peak oxygen uptake. IMLET loaded 50% of maximal inspiratory pressure (P Imax ). Respiratory muscle strength test, respiratory muscle endurance test (RMET), resting hypoxic ventilatory responsiveness (HVR) test, and incremental cycling test were performed pre- and post-training. Results: The extent of improvement in the P Imax was significantly greater in the IMLET group (24%) than in the ET group (8%) (p = .018), and an extended RMET time was observed in the IMLET group (p < .001). Minute ventilation ( ${\dot V_E}$ V ˙ E ) during exercise was unchanged in both groups before and after training, but tidal volume during exercise increased in the IMLET group. The increase in the exercise intensity threshold for muscle deoxygenation was similar in both groups (p < .001). HVR remained unchanged in both groups post-training. The exercise duration for the incremental exercise until reaching fatigue increased by 7.9% after ET and 6.9% after IMLET (p < .001). Conclusion: The 4-week IMLET improved respiratory muscle strength and endurance but did not alter HVR. Respiratory muscle deoxygenation was alleviated by exercise training, with a limited impact of inspiratory load training.