Effect of Moderate- or High-Intensity Inspiratory Muscle Strength Training on Maximal Inspiratory Mouth Pressure and Swimming Performance in Highly Trained Competitive Swimmers.

PURPOSE: Inspiratory muscle strength training (IMST) can improve exercise performance. Increased maximal inspiratory mouth pressure (MIP) could be beneficial for swimmers to enhance their performance. This study aimed to clarify the effect of high-intensity IMST for 6 weeks on MIP and swimming performance in highly trained competitive swimmers. METHODS: Thirty male highly trained competitive swimmers were assigned to high-intensity IMST (HI; n = 10), moderate-intensity IMST (MOD; n = 10), and control (n = 10) groups. The 6-week IMST intervention comprised twice daily sessions for 6 d/wk at inspiratory pressure threshold loads equivalent to 75% MIP (HI) and 50% MIP (MOD). Before and after the intervention, MIP and swimming performance were assessed. Swimming performance was evaluated in free and controlled frequency breathing 100-m freestyle swimming time trials in a 25-m pool. For controlled frequency breathing, participants took 1 breath every 6 strokes. RESULTS: The MIP values after 2 and 6 weeks of IMST in the HI and MOD groups were significantly higher than those before IMST (P = .0001). The magnitudes of the MIP increases after 6 weeks of IMST did not differ between the HI (13.4% [8.7%]) and MOD (13.1% [10.1%]) groups (P = .44). The 100-m freestyle swimming times under the controlled frequency condition were significantly shorter after IMST than those before IMST in both the HI (P = .046) and MOD (P = .042) groups. CONCLUSIONS: Inspiratory pressure threshold load equivalent to 50% MIP could be sufficient to improve MIP and swimming performance under the controlled frequency breathing condition in highly trained competitive swimmers.

Effect of inspiratory resistive training on diaphragm shear modulus and accessory inspiratory muscle activation.

This study aimed to elucidate changes in diaphragm and accessory inspiratory muscle (sternocleidomastoid (SCM) muscle and intercostal muscle (IC)) function after a 6-week training program. Nineteen male elite collegiate swimmers were assigned to either a control group (n = 9) or training group (n = 10). The subjects in the training group performed 30 maximum inspirations at a load resistance of 50% of maximum inspiratory mouth pressure (PImax) using an inspiratory muscle training device. These were conducted twice per day and 6 days per week. At baseline and after 6 weeks, PImax, shear modulus of the diaphragm, and electromyograms (EMG) of the SCM and IC during a maximal inspiratory maneuver were evaluated. Relative change in PImax was greater in the training group than in controls. The shear modulus during a PImax maneuver had increased significantly in both groups after 6 weeks. EMG amplitudes of the SCM increased in the training group after 6 weeks, but not in the control group. EMG amplitudes of the IC did not change after 6 weeks in either group. These results suggest that 6-week inspiratory resistive training significantly improves the activation of the SCM, which could be one of the major mechanisms behind increases in inspiratory muscle strength after resistive training. Novelty Six-week inspiratory resistive training increased diaphragm stiffness during maximal inspiration maneuver. Six-week inspiratory resistive training increased electromyogram amplitudes of the sternocleidomastoid during maximal inspiration maneuver.

Effects of Respiratory Muscle Endurance Training in Hypoxia on Running Performance.

PURPOSE: We hypothesized that respiratory muscle endurance training (RMET) in hypoxia induces greater improvements in respiratory muscle endurance with attenuated respiratory muscle metaboreflex and consequent whole-body performance. We evaluated respiratory muscle endurance and cardiovascular response during hyperpnoea and whole-body running performance before and after RMET in normoxia and hypoxia. METHODS: Twenty-one collegiate endurance runners were assigned to control (n = 7), normoxic (n = 7), and hypoxic (n = 7) groups. Before and after the 6 wk of RMET, incremental respiratory endurance test and constant exercise tests were performed. The constant exercise test was performed on a treadmill at 95% of the individual's peak oxygen uptake (V˙O2peak). The RMET was isocapnic hyperpnoea under normoxic and hypoxic conditions (30 min·d). The initial target of minute ventilation during RMET was set to 50% of the individual maximal voluntary ventilation, and the target increased progressively during the 6 wk. Target arterial oxygen saturation in the hypoxic group was set to 90% in the first 2 wk, and thereafter it was set to 80%. RESULTS: Respiratory muscle endurance was increased after RMET in the normoxic and hypoxic groups. The time to exhaustion at 95% V˙O2peak exercise also increased after RMET in the normoxic (10.2 ± 2.4 to 11.2 ± 2.6 min) and hypoxic (11.5 ± 2.6 to 12.6 ± 3.0 min) groups, but not in the control group (9.6 ± 3.2 to 9.4 ± 4.0 min). The magnitude of these changes did not differ between the normoxic and the hypoxic groups (P = 0.84). CONCLUSION: These results suggest that the improvement of respiratory muscle endurance and blunted respiratory muscle metaboreflex could, in part, contribute to improved endurance performance in endurance-trained athletes. However, it is also suggested that there are no additional effects when the RMET is performed in hypoxia.

Is man able to breathe once a minute for an hour?: the effect of yoga respiration on blood gases.

The ventilatory response to hypercapnia and arterial blood gases during ujjai respiration of once per minute for an hour were determined in a professional hatha yogi. The results suggest that lower chemosensitivity to hypercapnia in yoga practitioners may be due to an adaptation to low arterial pH and high PaCO2 for long periods.