Fiscus KA, Kaminski TW, Powers ME. Changes in lower-leg blood flow during warm-, cold-, and contrast-water therapy. To examine arterial blood flow in the lower leg during warm-, cold-, and contrast-water therapy. A crossover trial with repeated measurements on the dependent variable. Hydrotherapy area of a climate-controlled sports medicine clinic. A volunteer sample of 24 healthy men. Four randomly assigned treatments were performed on each subject on consecutive days. Arterial blood flow (mL per 100mL/min) from baseline measurements were recorded in a 3-minute to 1-minute on-off ratio for 20 minutes by using strain gauge plethysmography. Contrast therapy produced fluctuations in blood flow throughout the 20-minute treatment. Warm-water therapy (40°C) resulted in significant (P<.001) changes in blood flow compared with the control and contrast conditions. Cold-water therapy (13°C) did not produce significantly decreased blood flow as compared with the control condition. We suggest that further studies involving contrast therapy to the lower leg in injured populations be carried out to determine whether our initial findings are clinically relevant.