The Effect Of Ice Packs On Skin And Muscle Temperature At Rest And After Exercise

Abstract

Ice packs are used in the early treatment of muscular injuries. Several studies have shown the effects of ice on skin and muscle temperature in resting subjects. These studies do not reflect the situation of an athlete who is injured during an event and who immediately has an ice pack applied to the injury. The athlete may still have an elevated cardiac output and raised core temperature. This may affect temperature flux under the ice pack. PURPOSE The aim of this study was to investigate the effect of acute exercise on muscle cooling under an ice pack and compare it with muscle cooling in the resting state. METHODS 8 male subjects aged 19 – 27 y were studied. The thickness of the fat over the mid rectus femoris was measured for both legs. With the subject lying supine, a cutaneous temperature probe was placed on skin (Sk) over the middle of the left thigh in the anterior midline. Hypodermic needle tip thermistors were inserted into the subcutaneous fat (SC) and 1 cm into the muscle (Ms), so as to lie beneath the temperature probe. A 20 cm by 10 cm pack of crushed ice in a wet towel, was placed longitudinally over the temperature probe and left in situ for 15 minutes. Temperature measurements were recorded every minute for 5 minutes before application of the ice pack, during the ice application and for 45 min after removal of the ice. The hypodermic needle probes were removed and an hour later subjects underwent a ramped VO2max test on a treadmill. On completion of the test the temperature probe and hypodermic needle thermistors were inserted into the right leg. After 5 minutes, an ice pack was applied for 15 min and recordings were made as before. RESULTS Average subcutaneous fat thickness was 0.43 cm and treadmill running time was 12.2 ± 1.1 min. After the treadmill run, skin, subcutaneous and muscle temperatures were 0.9 ±1.3, 1.0 ± 0.7 and 1.3 ± 0.8 °C higher than at rest. After 15 min of icing, temperatures fell in the exercised limb by 22.7 ± 1.5 °C (Sk), 13.5 ± 4.2 °C (SC) and 9.3 ± 5.5°C (Ms) and in the control limb by 20.7 ± 2.9 °C, (Sk), 11.4 ± 2.0 °C (SC) and 8.7 ± 2.6°C (Ms). 45 min after removing the ice pack the reduction in temperature in the exercised leg was 3.3 ± 1.3 °C (Sk), 4.6 ± 1.4 °C (SC) and 5.3 ± 1.6 °C (Ms) and in the control limb, 3.2 ± 0.8 °C (Sk), 5.0 ± 0.7 °C (SC) and 5.5 ± 0.9 °C (Ms). CONCLUSIONS Acute exercise, with an associated rise in cardiac output, enhanced muscle perfusion and increased muscle temperature does not affect either the rate or degree of cooling produced by the application of an ice pack for 15 minutes.