Effects of short-term oral salbutamol administration on exercise enduranceand metabolism

The present study examined whether oral short-term administration of salbut amol (Sal) modifies performance and selected hormonal and metabolic variabl es during submaximal exercise. Eight recreational male athletes completed t wo cycling trials at 80-85% peak O-2 consumption until exhaustion after eit her gelatin placebo (Pla) or oral Sal (12 mg/day for 3 wk) treatment, accor ding to a double-blind and randomized protocol. Blood samples were collecte d at rest, after 5, 10, and 15 min, and at exhaustion to determine growth h ormone (GH), cortisol, testosterone, triiodothyronine (T-3), C peptide, fre e fatty acid (FFA), blood glucose, lactate, and blood urea values. Time of cycling was significantly increased after chronic Sal intake (Sal: 30.5 +/- 3.1 vs. Pla: 23.7 +/- 1.6 min, P < 0.05). No change in any variable was fo und before cycling except a decrease in blood urea concentration and an inc rease in T-3 after Sal that remained significant throughout the exercise te st (P < 0.05). Compared with rest, exercise resulted in a significant incre ase in GH, cortisol, testosterone, T-3, FFAs, and lactate and a decrease in C peptide after both treatments with higher exercise FFA levels and exhaus tion GH concentrations after Sal (P < 0.05). Sal but not Pla significantly decreased exercise blood glucose levels. From these data, short-term Sal in take did appear to improve performance during intense submaximal exercise w ith concomitant increase in substrate availability and utilization, but the exact mechanisms involved need further investigation.