The Effects of Expiratory Muscle Strength Training (EMST) in Collegiate Swimmers

Abstract

The respiratory system may be the limiting factor for performance in highly trained swimmers. We investigated the effects of 4 weeks EMST on swim times, subjective ratings of perceived exertion (RPE) and breathlessness (RB). Varsity swimmers of the University of Florida were recruited and randomized to either EMST (n=9) or air flow training (AFT, n=8). EMST was performed using pressure threshold trainers. The pressure load was set to 75% of swimmer's maximum expiratory pressure. Each week the pressure load was increased by 15%. AFT was conducted using peak flow meters and subjects were instructed to target a specific expiratory flow rate which was also increased each week about 15%. EMST and AFT were performed for 5 sets of 5 breaths with 1 min rest between sets, 5 days per week for 4 weeks. A 6 x 100 m freestyle test was used to evaluate swimming times, RPE and RB pre- and post-training. Average swim time decreased by −1.0 ± 1.7 s (p = 0.084) in the EMST group and −0.2 ± 1.6 s in the AFT group (p = 0.378), however, the change was not statistically significantly different between the groups (p = 0.204). Post-training, ratings of breathlessness tended to worsen in the AFT group and ratings of perceived exertion tended to improve in the EMST group. The results demonstrate that EMST may be more effective than AFT in improving swimming times, RPE and RB in a maximal effort interval swim.