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[RC] A heat sink concept - Ridecamp Guest

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Authors DA Grahn, VH Cao, HC Heller
Title   Heat extraction through the palm of one hand improves aerobic exercise 
endurance in a hot environment
Full source     Journal of Applied Physiology, 2005, Vol 99, Iss 3, pp 972-978

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 
mmHg) to an entire hand (to increase blood volume) and a heat sink (18-22 
degrees C) to the palmar surface were used to draw heat out of the circulating 
blood. Subjects walked uphill (5.63 km/h) on a treadmill in a 40 degrees C 
environment. Slopes of the treadmill were held constant during paired 
experimental trials (with and without the device). Heat extraction attenuated 
the rate of esophageal temperature rise during exercise (2.1  0.4 degrees and 
2.9  0.5 degrees C/h, mean  SE, with and without the device, respectively; n = 
8) and increased exercise duration (46.1  3.4 and 32.3  1.7 min with and 
without the device, respectively; n 18). Hand cooling alone had little effect 
on exercise duration.(34.1  3.0, 38.0  3.5, and 57.0  6.4 min, for control, 
cooling only, and cooling, and subatmospheric pressure, respectively; n = 6). 
In a longer term study, nine subjects participated in two or four trials per 
week for 8 wk. The individual workloads (treadmill slope) were varied weekly. 
Use of the device had a beneficial effect on exercise endurance at all 
workloads, but the benefit proportionally decreased,at higher workloads. It is 
concluded that heat can be efficiently removed from the body by using the 
described technology and that such treatment can provide a substantial 
performance benefit in thermally stressful conditions.

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