Exercise limitation of acetazolamide at altitude (3459 m).

Objective: To assess the effect of acetazolamide (Az) on exercise performance during early acclimatization to altitude.

Methods: Az (250 mg twice daily) or placebo was administered for 3 days in a double-blind, randomized manner followed by a rapid ascent to 3459 m in the Italian Alps. Twenty healthy adults (age range, 18-67 years) were tested at 60% of sea-level peak power output for 15 minutes on a bicycle ergometer after 16 to 27 hours of altitude exposure.