In situations where the accumulation of internal heat limits physical performance, enhanced heat extraction from the body should improve performance capacity. The combined application of local subatmospheric pressure (35-45 mm Hg) to an entire hand (to increase blood volume) and a heat sink (18-22 °C) to the palmar surface was used to draw heat out of the circulating blood. Subjects walked uphill (5.63 Km/h) on a treadmill in a 40 °C environment. Slopes of the treadmill were held constant during paired experimental trials (with and without use of the device). Heat extraction attenuated the rate of esophageal temperature rise during exercise (2.1 ± 0.4 °C/h vs. 2.9 ± 0.5 °C/h, with vs. without use of the device, n=8, mean ± SEM) and increased exercise duration (46.1± 3.4 minutes vs. 32.3 ± 1.7 minutes, with vs. without use of the device, n=18). Hand cooling alone had little effect on exercise duration (controls, 34.1 ± 3.0 min.; cooling only, 38.0 ± 3.5 min, cooling and subatmospheric pressure, 57.0 ± 6.4 min, n= 6). In a longer-term study, nine subjects participated in two or four trials/week for eight weeks. The individual work loads (treadmill slope) were varied weekly. Use of the device had a beneficial effect on exercise endurance at all work loads, but the benefit proportionally decreased at higher work loads. It is concluded that heat can be efficiently removed from the body by using the described technology and such treatment can provide a substantial performance benefit in thermally stressful conditions.