Cooling Times of the Gastrocnemius Vary Based on Adipose Tissue Thickness

Abstract

It has been reported there is a direct relationship between adipose tissue thickness and skeletal muscle cooling time. Therefore, a standard ice application of 20-25min may be suitable to cool the injured muscle of lean athletes, but not effective for larger athletes. Previous research has suggested different cooling times for various skinfold thicknesses of the thigh, however, this has not been assessed in the gastrocnemius. PURPOSE: To compare skeletal muscle temperature change after 25min of ice application. METHODS: Fourteen healthy adults (2 males, 12 females; 22.8±2.8 years; 165.9±12.0cm; 65.9±15.5kg) participated. Participants were placed prone. The thickest part of the dominant lower leg was identified with circumference measurements. The medial portion of the gastronemius was pinched 3 times with a skinfold caliper. An average was determined and was divided by two. 10 millimeters was added to this number and an intramuscular thermocouple was inserted to that depth. The thermocouple was marked with a permanent marker to ensure proper depth was achieved. Participants were randomized into either an ice group (750g bag of crushed ice) or sham group (750g bag of candy corn). This was a crossover design, so the participants received the opposite treatment 1 week later. Temperature was recorded every second. Participants were analyzed in 3 groups based on skinfold thickness; 11-20mm, 21-30mm, and 31-40mm. RESULTS: A one-way ANOVA was run to analyze change in temperature from baseline at 25min for all groups. There was a significant difference in intramuscular temperature change between groups (p=.048). Baseline temperature was 36.95±1.47°C (11-20mm), 35.83±1.77°C (21-30mm) and 36.08±3.44°C (31-40mm). Post hoc tests revealed that the 31-40mm group had significantly less temperature change (-4.03±.11°C) than the 11-20mm (-7.34±2.14°C) (p=.043) and 21-30mm (-7.97±1.57°C) (p=.016) groups. CONCLUSIONS: Adipose tissue thickness did affect intramuscular temperature change at 25min, with larger skinfold thicknesses resulting in less change. It is important for clinicians to realize that if intramuscular cooling is the goal of the cryotherapy session, than larger amounts of adipose tissue over the muscle will result in a decreased rate of cooling and more time may be needed than the standard application time.