| Context: Cryotherapy is the most commonly used therapeutic modality in health care. Although clinicians utilize cryotherapy frequently during therapeutic exercises, effects of cryotherapy on passive tissue mechanical properties such as musculotendinous stiffness (MTS) are not conclusive. Objective: To determine if a 30-minute cryotherapy application to the ankle plantarflexor muscle group or ankle joint influenced passive mechanical resistive properties. Design: Randomized controlled study. Setting: Controlled laboratory setting. Participants: Thirty-six recreationally active individuals (males: n=16, females: n=19) with no history of lower leg injury for 6 months prior to data collection voluntarily participated. Intervention: Subjects reported to the laboratory 4 times to determine if a sex (males or females), treatment location (a 2-kg crushed ice bag over the posterior lower leg muscles, ankle joint, or nothing), day (1st, 2nd, or 3rd), and time (pre-treatment, 10-minute and 20-minute during-treatment, immediately post-, 10-, 20-, and 30-minute post-treatment) influenced passive resistive properties during passive ankle dorsiflexion on the isokinetic dynamometer. Main Outcome Measures: Maximum passive ankle dorsiflexion range of motion (ROM), maximum passive ankle plantarflexion torque, absolute passive ankle plantarflexor MTS at 4 common joint angles (theta1-4 ), relative MTStheta1-4 normalized by corrected calf girth (CCG) or cross sectional area (CSA) of the gastrocnemius, surface electromyography (sEMG) on the ankle plantarflexor muscles, and surface skin temperature on the lower leg and ankle joint were measured. Results: A 30-minute crushed ice bag application did not influence passive ROM ( P>.05). Significant treatment location by time interaction in passive torque (F12,658=1.77, P=.049) was observed. Significant sex by treatment location interaction in MTStheta 1 (F2,658=3.55, P=.029) and CSAMTStheta1-4 (P<.05) were also observed. Sex and time main effects were also observed in MTStheta1-4 (P<.05) and CCGMTStheta1-4 (P<.05). sEMG amplitudes remained less than 1% on each ankle plantarflexor muscle during passive ankle dorsiflexion motion. Skin surface temperature significantly decreased during and following the cryotherapy (P<.05). Conclusions: Cryotherapy did not influence passive ankle dorsiflexion ROM. Passive torque increased during and following the cryotherapy application. Although absolute MTS, and relative MTS increased during and following the application, there were no treatment effects because the control group also responded in the same manner. |
