Kressler, J., Stoutenberg, M., Roos, B., Friedlander, A. L., Perry, A. C., Signorile, J., Viskochill, R. & Jacobs, K. A. (2010). Sildenafil does not improve peak exercise capacity during acute hypoxia in trained men or women. Presentation 1036 at the 2010 Annual Meeting of the American College of Sports Medicine, Baltimore, Maryland; June 2-5.

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"Sildenafil has been shown to improve maximal exercise capacity in men during severe hypobaric and normobaric hypoxia (~4300-5800 m) by enhancing pulmonary vasodilation, thereby improving cardiovascular and pulmonary function and enhancing oxygen delivery. However, with less severe hypoxia (~3818 m) women did not exhibit such benefits."

This study determined whether sildenafil enhanced exercise capacity in endurance-trained men and women during acute normobaric hypoxia (~3900 m). Following determination of peak exercise capacity (Wpeak) at sea-level, men (N = 11; ~25 years) and women (N = 10; ~27 years) completed two Wpeak (at least 48 hours apart) trials one hour following the ingestion of either a placebo or 50 mg of sildenafil in a double-blind randomized protocol in acute normobaric hypoxia (12.8% FIO2, ~3900 m). Heart rate, stroke volume, and cardiac output were measured continuously by noninvasive impedance cardiography while arterial oxygen saturation (SaO2) was measured by pulse oximetry.

Sildenafil citrate did not affect Wpeak in either men or women. Similarly, oxygen saturation at peak was unaffected for both genders. Peak cardiovascular hemodynamics tended to be higher with sildenafil than placebo, but did not differ significantly for men or women.

Implication. Sildenafil does not enhance exercise capacity of endurance-trained men or women during acute normobaric hypoxia (~3900 m).

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