Acute effects of cold pack on mechanical properties of the quadriceps muscle in healthy subjects.

Purpose: To examine the effects of local cooling on mechanical properties of the quadriceps muscle in healthy subjects.

Subjects: Thirty-nine healthy subjects (27 women, 12 men, mean age 39, range 20-62) volunteered.

Methods: A cold gel pack was applied to the quadriceps muscle for 20 min. Properties were quantified by analyzing the frequency (tension), decrement (elasticity) and stiffness of damped oscillations and the compliance of the muscle before, immediately after and after 15-min after cooling.

Results: The largest responses immediately after cooling were seen in the oscillation decrement parameter, 7.9 (3.7-12.1) %, and in the compliance parameter, -7.5 (-9.8 to -5.3) %. Responses in the oscillation frequency, 6.5 (2.3-10.6) %, and stiffness parameters, 4.0 (0.8-7.1) %, were also statistically significant. The compliance still showed a -6.1 (-7.7 to -4.5) % decrease after the 15 min recovery phase, while no remaining alteration was found in the oscillation parameters.

Conclusion: The quadriceps muscle became tenser, stiffer, and less elastic as a result of cooling, and the mechanical properties were not fully recovered after 15 min. Careful warming-up is suggested after cooling to enable normalization of mechanical properties of the muscle and to avoid injuries.