Sildenafil does not improve steady state cardiovascular hemodynamics, peak power, or 15-km time trial cycling performance at simulated moderate or high altitudes in men and women - Kressler, J; Stoutenberg, M; Roos, B A; Friedlander, A L; Perry, A C; Signorile, J F; Jacobs, K A (Eur J Appl Physiol, 2011)