Skip Navigation LinksHome > May 2005 - Volume 37 - Issue 5 > Respiratory Muscle Strength May Explain Hypoxia-Induced Decr...
Medicine & Science in Sports & Exercise:
Basic Sciences: Original Investigations

Respiratory Muscle Strength May Explain Hypoxia-Induced Decrease in Vital Capacity


Collapse Box


Purpose: High altitude exposure has consistently been reported to decrease forced vital capacity (FVC), but the mechanisms accounting for this observation remain incompletely understood. We investigated the possible contribution of a hypoxia-related decrease in respiratory muscle strength.

Methods: Maximal inspiratory and expiratory pressures (MIP and MEP), sniff nasal inspiratory pressure (SNIP), FVC, peak expiratory flow rate (PEF), and forced expiratory volume in 1 s (FEV1) were measured in 15 healthy subjects before and after 1, 6, and 12 h of exposure to an equivalent altitude of 4267 m in a hypobaric chamber.

Results: Hypoxia was associated with a progressive decrease in FVC (5.59 ± 0.24 to 5.24 ± 0.26 L, mean ± SEM, P < 0.001), MIP (130 ± 10 to 114 ± 8 cm H2O, P < 0.01), MEP (201 ± 12 to 171 ± 11 cm H2O, P < 0.001), and SNIP (125 ± 7 to 98 ± 7 cm H2O, P < 0.001). MIP, MEP, and SNIP were strongly correlated to FVC (r ranging from 0.77 to 0.92). FEV1 didn’t change, and PEF increased less than predicted by the reduction in air density (11–20% of sea-level value compared with 32% predicted).

Conclusion: We conclude that a decrease in respiratory muscle strength may contribute to the decrease in FVC observed at high altitude.

©2005The American College of Sports Medicine


Article Tools


Article Level Metrics

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.

Connect With Us