Cold gel effects verified by thermal skin sensors and simultaneous dynamic thermography

Cold therapy is used daily by hundreds of thousands of patients in the field of sports and occupational medicine. However, the objective temperature change and the duration of effect on treated area have to our knowledge not been studied .To determine the temperature changes and the duration of effect when cold gel is applied to intact skin. Methods: We recorded surface temperature of right vastus lateralis-muscle in 6 healthy adults with thermal sensors taped to the border and to the center of a 6x12 cm area. Also temperature was measured from outside areas and to the left leg and imaged simultaneously from distance of 60 cm once every minute with a medical thermal system. Imaging was done before and during cooling the area when a standard amount of cold gel applied to the skin. Results: Highly significant cooling of gel area was evident in all subjects. The relative dynamic change of temperature was similar within 95% confidence limits both in surface sensors and in the corresponding area of thermal images. The average drop of local temperature was 4 degrees, maximal effect appeared at 15-20 min from application and duration of effect was 60-90 min. Below knee, but not in thighs, we observed an average cooling of 1 degree during the 70-90 min recording period. The effect of cold gel as seen in surface temperature is highly local and prominent. The observed bilateral preservation of medial and lateral thigh temperature may be related to compensatory circulatory mechanisms upon cold gel application