The Effect of Acute and Chronic Exposure to Hypobaric Hypoxia on Loaded Squat Jump Performance.

The present study aimed (1) to compare loaded squat jump performance after an acute and chronic exposure to a moderate natural altitude between normoxia and hypobaric hypoxia conditions, and (2) to analyze the effect of an altitude training camp on loaded jump squat development. Sixteen male swimmers (17.1 ± 0.8 years) took part in a 17-day training camp at a natural moderate altitude. They were randomly tested in counterbalanced order on days 1 and 3 in normoxia and hypoxia (pretest) and on days 15 and 17 again in normoxia and hypoxia (posttest). The peak velocity reached with loads equivalent to 25%, 50%, 75% and 100% of swimmers' pretest body weight in the loaded squat jump exercise was the dependent variable analyzed. An overall increase in peak velocity during the test performed in hypoxia of 6.5% in pretest (p < 0.001, ES = 0.98) and 4.5% in posttest (p < 0.001, ES = 0.81) was observed. An overall increment in peak velocity of 4.0% considering the data for normoxia tests (p < 0.001, ES = 0.61) and 2.1% considering the data for hypoxia tests (p = 0.008, ES = 0.36) was achieved after the altitude training camp. These results highlight the beneficial effects of hypobaric hypoxia on jump performance after short and longer term exposure to a natural moderate altitude. The increase in loaded squat jump performance following the 17-day training camp suggests that altitude training could constitute a favorable stimulus in explosive strength.