The effect of 400 µg inhaled salbutamol on 3 km time trial performance in a low humidity environment

The objectives of the study were to investigate whether 400 µg inhaled salbutamol influences 3 km running time-trial performance and lung function in eucapnic voluntary hyperpnoea positive (evh+ve) and negative (evh-ve) individuals. fourteen male participants (22.4 ± 1.6yrs; 76.4 ± 8.7kg; 1.80 ± 0.07 m); (7 evh+ve; 7 evh-ve) were recruited following written informed consent. all participants undertook an evh challenge to identify either evh+ve (↓ fev1>10%) or evh-ve (↓ fev1<10%). participants performed three separate 3 km running time-trials in a low-humidity (20-25%) environment on a non-motorized treadmill,15 minutes following inhalation of salbutamol (400 µg),placebo (non-active inhalant) or control (no inhalant),in a randomized,single-blind,repeated measures design. forced vital capacity maneuvers were performed at baseline,10 minutes post inhalation and post time-trial. time to complete 3 km and lung function data were analyzed using mixed model repeated measures anova. significance was assumed at p < 0.05. all evh+ve participants had fev1 falls from baseline between 10-25% post-challenge. there was no difference in performance time between trial conditions in evh+ve (1012.7 ± 129.6s; 1002.4 ± 123.1s; 1015.9 ± 113.0s) (p = 0.774) and evh-ve (962.1 ± 99.2s; 962.0 ± 76.2s; 950.8 ± 84.9s) (p = 0.401) groups for salbutamol,placebo and control trials,respectively. exercising heart rate was significantly higher (p = 0.05) in the salbutamol trial (183 ± 8 beatsˑmin-1) compared to control (180 ± 9 beatsˑmin-1) with a trend towards significance (p=0.06) in the placebo trial (179 ± 9 beatsˑmin-1) for the pooled groups,no differences were seen between trials in groups individually. there was an increase in fev1 in both evh+ve (4.01 ± 0.8l; 4.26 ± 0.7l; 4.25 ± 0.5l) and evh-ve (4.81 ± 0.4l; 5.1 ± 0.4l; 5.1 ± 0.5l) groups which was significant post-inhalation (p = 0.01; p = 0.02),but not post-time-trial (p = 0.27; p = 0.06),respectively,following salbutamol. evh+ve participants did not demonstrate significant falls (>10% from baseline) in fev1 following any time-trial. administration of 400µg inhaled salbutamol does not improve 3 km time-trial performance in either mild evh+ve or evh–ve individuals despite significantly increased hr and fev1. ©journal of sports science and medicine.