title: Sildenafil has little influence on cardiovascular hemodynamics or 6-km time trial performance in trained men and women at simulated high altitude.
abstract: Sildenafil improves maximal exercise capacity at high altitudes (∼4350-5800 m) by reducing pulmonary arterial pressure and enhancing oxygen delivery, but the effects on exercise performance at less severe altitudes are less clear.
  
  
  OBJECTIVE
  To determine the effects of sildenafil on cardiovascular hemodynamics (heart rate, stroke volume, and cardiac output), arterial oxygen saturation (SaO2), and 6-km time-trial performance of endurance-trained men and women at a simulated altitude of ∼3900 m.
  
  
  METHODS
  Twenty men and 15 women, endurance-trained, completed one experimental exercise trial (30 min at 55% of altitude-specific capacity +6-km time trial) at sea level (SL) and two trials at simulated high altitude (HA) while breathing hypoxic gas (12.8% FIo2) after ingestion of either placebo or 50 mg sildenafil in double-blind, randomized, and counterbalanced fashion.
  
  
  RESULTS
  Maximal exercise capacity and SaO2 were significantly reduced at HA compared to SL (18%-23%), but sildenafil did not significantly improve cardiovascular hemodynamics or time-trial performance in either men or women compared to placebo and only improved SaO2 in women (4%). One male subject (5% of male subjects, 2.8% of all subjects) exhibited a meaningful 36-s improvement in time-trial performance with sildenafil compared to placebo.
  
  
  CONCLUSIONS
  In this group of endurance trained men and women, sildenafil had very little influence on cardiovascular hemodynamics, SaO2, and 6-km time-trial performance at a simulated altitude of ∼3900 m. It appears that a very small percentage of endurance-trained men and women derive meaningful improvements in aerobic performance from sildenafil at a simulated altitude of ∼3900 m.
authors.affiliation: University of Miami, Department of Kinesiology and Sport Sciences, Coral Gables, Florida 33146, USA. k.jacobs@miami.edu
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Jacobs
authors.forename: Jochen
authors.initials: J
authors.lastname: Kressler
authors.forename: Mark
authors.initials: M
authors.lastname: Stoutenberg
authors.forename: Bernard A
authors.initials: BA
authors.lastname: Roos
authors.forename: Anne L
authors.initials: AL
authors.lastname: Friedlander
mesh_terms: D000328:Adult; D000531:Altitude; D000704:Analysis of Variance; D001794:Blood Pressure / Q000187:drug effects; D005080:Exercise Test / Q000187:drug effects; D017079:Exercise Tolerance / Q000187:drug effects*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects*; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D012044:Regression Analysis; D000068677:Sildenafil Citrate; D013318:Stroke Volume / Q000187:drug effects; D013450:Sulfones / Q000494:pharmacology*; D013997:Time Factors; D014665:Vasodilator Agents / Q000494:pharmacology*; D055815:Young Adult
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate; D010100:Oxygen