Heather Lunt1, Michael Tipton. 1. Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Spinnaker Building, Cambridge Road, Portsmouth, PO1 2ER, UK, heather.lunt@port.ac.uk.
Abstract
PURPOSE: This study investigated possible sex-related and intra-menstrual differences in local vascular and skin temperature responses when conductive cooling was applied to the soles of the feet. METHOD: Twelve females and twelve males exposed the soles of their feet to a cooling plate (which cooled from 35 to 15 °C) on two occasions 12-15 days apart. For females, sessions took place during their inactive and active contraceptive pill phases. Tip of Great toe temperature and Great toe skin blood flow were recorded throughout. RESULTS: Females' feet cooled to a greater extent than males' (P = 0.001). Sensitivity of toe skin blood flow to changes in skin temperature (1 or 2 °C) was not different between males and females. Dimensions of males' feet were larger than females' (P < 0.05) and correlations between foot dimensions and toe skin cooling were found (r = 0.728, P < 0.001). Analysis of the residual variance showed that foot volume, contact area and skin blood flow correlated with the rate of toe skin cooling (r = 0.812, r (2) = 0.659, P < 0.001). No intra-menstrual differences were found. CONCLUSION: The feet of females cooled at a faster rate than those of males in response to the same conductive cooling stimulus to the soles of the feet. However, similar reductions in skin blood flow were found for the same change in toe skin temperature. Therefore, sex related differences may be due to the differing dimensions of the feet, but further research including males and females matched for foot dimensions are required to confirm this mechanism.
PURPOSE: This study investigated possible sex-related and intra-menstrual differences in local vascular and skin temperature responses when conductive cooling was applied to the soles of the feet. METHOD: Twelve females and twelve males exposed the soles of their feet to a cooling plate (which cooled from 35 to 15 °C) on two occasions 12-15 days apart. For females, sessions took place during their inactive and active contraceptive pill phases. Tip of Great toe temperature and Great toe skin blood flow were recorded throughout. RESULTS: Females' feet cooled to a greater extent than males' (P = 0.001). Sensitivity of toe skin blood flow to changes in skin temperature (1 or 2 °C) was not different between males and females. Dimensions of males' feet were larger than females' (P < 0.05) and correlations between foot dimensions and toe skin cooling were found (r = 0.728, P < 0.001). Analysis of the residual variance showed that foot volume, contact area and skin blood flow correlated with the rate of toe skin cooling (r = 0.812, r (2) = 0.659, P < 0.001). No intra-menstrual differences were found. CONCLUSION: The feet of females cooled at a faster rate than those of males in response to the same conductive cooling stimulus to the soles of the feet. However, similar reductions in skin blood flow were found for the same change in toe skin temperature. Therefore, sex related differences may be due to the differing dimensions of the feet, but further research including males and females matched for foot dimensions are required to confirm this mechanism.
Authors: Dan P Stephens; Lee Ann T Bennett; Ken Aoki; Wojciech A Kosiba; Nisha Charkoudian; John M Johnson Journal: Am J Physiol Heart Circ Physiol Date: 2002-01 Impact factor: 4.733
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