Inspiratory muscle training fails to improve endurance capacity in athletes

Purpose: The purpose of this study was to examine the effects of specific inspiratory muscle training (IMT) on respiratory muscle strength and endurance and whole-body endurance exercise capacity in competitive endurance athletes. Methods: Seven collegiate distance runners (5 male/2 female; (V) over dot O-2max = 59.9 +/- 11.7 mL.kg(-1).min(-1)), were recruited to participate in this study. Initial testing included maximal oxygen consumption ((V) over dot O-2max), sustained maximal inspiratory Mouth Pressure (MIP). breathing endurance time (BET) at 60% MIP and endurance run time (ERT) at 85% (V) over dot O-2max Heart rate (HR). minute ventilation ((V) over dot (E)), Oxygen consumption ((V) over dot O-2), and ratings of perceived dyspnea (RPD) were recorded at 5-min intervals and during the last minute of the endurance run. Blood lactate concentration (BLC) was also obtained immediately before and at 2 min after the endurance run. All testing was repeated after 4 wk of IMT (50-65% MIP similar to25 min.d(-1), 4-5 sessions/week, 4 wk), Results: After 4 wk of IMT, MIP and BET were significantly increased compared with pretraining values (P < 0.05). No significant differences between pre and post values were observed in (V) over dot O-2max or ERT at 85% (V) over dot O-2max after IMT. No significant differences between pre and post values were detected in HR. (V) over dot (E), (V) over dot O-2, or RPD during the endurance run as measured at steady state and end of the test after IMT. BLC was not significantly different before or at 2 min after the endurance run between pre and post IMT. Conclusion: These results suggest that IMT significantly improves respiratory muscle strength and endurance. However. these improvements in respiratory muscle function are not transferable to (V) over dot O-2max or endurance exercise capacity as assessed at 85% (V) over dot O-2max in competitive athletes.