Special force units and military personnel undergo demanding physical exercise and might benefi t from high-intensity respiratory muscle training (RMT) by increasing their endurance performance. This study examined the effects of a 6-week high-intensity RMT on running performance and oxygen uptake (VO 2 max) in a group of German Special Force Squad members. Methods: 17 participants were randomly assigned to a training or control group. Baseline and post-testing included a ramp test, as well as an incremental test on a treadmill, performed to physical exhaustion. VO 2 , respiratory exchange ratio, and heart rate were measured breath by breath. Furthermore, maximum running speed (V max ), 4 mmol·l 1 lactate threshold (V 4 ) and perception of respiratory effort were determined. During pulmonary testing, sustained maximum inspiratory and expiratory pressure (PI max and PE max ) were obtained. RMT was performed daily at approximately 90% PI max for 6 weeks with 2 × 30 breath cycles using an Ultrabreathe lung trainer. Results: No statisti- cal differences were detected between the groups for any parameter after RMT. Conclusion: High-intensity RMT did not show any benefi ts on VO 2 max and endurance performance and are unlikely to be of benefi t to military or paramilitary training programs for an increase in endurance performance.
