 Popliteal and femoral venous peak blood flow velocities were measured bilaterally using a Doppler ultrasound device at 0, 15, 120, and 240 minutes. The same ultrasound technician obtained all Doppler studies on all subjects throughout the study. All Doppler tracings were be read by the same independent reader in a blinded fashion. Immediately following completion of each 4 hour session of electrical foot stimulation or intermittent pneumatic compression, subjects were asked to complete a brief questionnaire regarding their acceptance and tolerance of electrical stimulation or intermittent pneumatic compression. 