Temperature changes in the human leg during and after two methods of cryotherapy

To compare the cooling and rewarming effects of two clinical 20-minute cryotherapy treatments on the temperature of the human leg.

Sixteen subjects were randomly treated with either 20 minutes of a 1.8-kg crushed-ice pack, placed directly over the left calf, or a 20-minute immersion in a cold (10 degrees C) whirlpool. Data were collected at a university human performance research laboratory.

Seventeen male and 15 female healthy college students.

Subcutaneous and muscle tissue temperatures were measured by 26-gauge hypodermic needle microprobe inserted in the calf, just below the skin, or 1 cm below the subcutaneous fat, respectively.

There was no significant difference in the decrease in intramuscular temperatures between treatments (t (30) = -1.76, P = .09). The ice pack treatment significantly decreased the subcutaneous temperature more than the whirlpool (t (30) = -2.64, P = .01). The subcutaneous temperature rewarmed significantly more in the ice pack group (12.3 +/- 3.3 degrees C) than the cold whirlpool (7.4 +/- 2.1 degrees C) (t (30) = 4.98, P = .0000). The ice pack group's intramuscular temperature increased over each 5-minute interval of the 30-minute post-treatment period for an overall increase of 2.0 +/- 3.1 degrees C. During the 30-minute post- treatment the cold whirlpool group continued to cool, for an overall decrease of 1.8 +/- 1.4 degrees C. This difference between groups at the end of the 30-minute post-treatment was significant (t(30) = 4.44, P = .0001).

As administered in our protocol, cold whirlpool is superior to crushed-ice packs in maintaining prolonged significant temperature reduction after treatment.