Exercise and Quadriceps Muscle Cooling Time

Context: Cryotherapy is commonly used for a variety of purposes; however, the body’s response to cryotherapy immediately postexercise is unknown. Objective: To investigate the effect of prior exercise on crushed-ice–bag treatment of a large muscle group. Design: 2 x 3 repeated-measures design on depth (1 cm and 2 cm below adipose tissue) and treatment (exercise followed by ice, exercise followed by no ice, and no exercise followed by ice). Setting: Sports Injury Research Laboratory. Patients or Other Participants: Six physically active, uninjured male volunteers. Intervention(s): For the 2 exercise conditions, subjects rode a stationary cycle ergometer at 70% to 80% of their age-predicted maximum heart rate, as calculated by the Karvonen method. For the no-exercise condition, subjects lay supine on a treatment table. The cryotherapy treatment consisted of a 1-kg ice bag applied to the anterior mid thigh. For the no-ice condition, subjects lay supine on a treatment table. Main Outcome Measure(s): Time required for the intramuscular temperatures at the 1-cm and 2-cm depths below adipose tissue to return to pre-exercise baseline and time required to cool the 1-cm and 2-cm depths to 108C below the pre-exercise temperature. Results: The time to cool the rectus femoris to the pre-exercise temperature using a crushed-ice–bag treatment was reduced by approximately 40 minutes (P<.001). The ice bag cooled the 1-cm and 2-cm depths to the pre-exercise temperature within 7 minutes (P=.38), but the 2-cm tissue depth took nearly 13.5 minutes longer to cool than the 1-cm depth when no ice was applied (P<.001). The 1-cm depth cooled to 10C below the pre-exercise temperature about 8 minutes sooner than the 2-cm depth, regardless of whether the tissue was exercised or not (P<.001). Exercise shortened the cooling time to 10C below the pre-exercise temperature by approximately 13 minutes (P=.05). Conclusions: Exercise before cooling with a crushed-ice bag enhanced the removal of intramuscular heat.