Abstract

The effect of caffeine on exercise time over a specified distance (approx. 21 km) was investigated in well-trained cross-country skiers (14 subjects) both atlow (300 m above sea level) and high (2900 m above sea level) altitudes. Each subject participated in two races at both altitudes - one after caffeine ingestion (6 mg/kg body weight) and one after placebo on a double-blind basis. At low altitudes, after half the distance, the race time with caffeine was decreased 0.94 of the mean time (corresponding to approx. 33 s) as compared to placebo, whereas after the full distance the corresponding decrease was 1.7 of the mean time (corresponding to approx. 59 s). At high altitudes, the race time was significantly faster with caffeine than with placebo, both after one and two laps, 2.19 and 3.18 of the mean time, respectively (correspon ding to approx. 101 s and 152 s). The perceived exertion was similar at low and high altitudes independent of medication. In conclusion, there are indications that caffeine induces an increased performance capacity for crosscountry skiers at low altitudes. Furthermore, an even more marked improvement after caffeine as compared to placebo was found at high altitudes. Verf.-Referat