The Acute Effect of Cryotherapy on Muscle Strength and Shoulder Proprioception.

CONTEXT

Cryotherapy, a common intervention used by clinicians, poses several benefits in managing acute injuries. However, cooling muscle tissue can interfere with muscular properties and the sensory-motor system.

OBJECTIVE

The aim of this study was to analyze the influence of cryotherapy with a crushed-ice pack on shoulder proprioception concerning joint position sense, force sense, the threshold for detecting passive movement, and maximal force production.

DESIGN

A randomized, double-blind controlled trial.

PARTICIPANTS

48 healthy women aged 22.6 ± 0.4 y with a mean body mass index of 22.8 ±0.37 kg/m2 and a percentage of body fat of 15.4 ± 1.5%.

METHODS

In the experimental group, a crushed-ice pack was applied to the shoulder for 15 min, whereas participants in the control group applied a sandbag at skin temperature, also for 15 min. An isokinetic dynamometer was used to assess maximal voluntary contraction, force sense, joint position sense, and the threshold for detecting passive movement.

RESULTS

Paired sample t tests revealed that maximal voluntary isometric contraction decreased significantly after cryotherapy (P ≤ .001), or approximately 10% of the reduction found in both muscular groups assessed. Shoulder position sense (P < .001) and the threshold for detecting passive movement (P = .01 and P = .01 for lateral and medial shoulder rotator muscles, respectively) also suffered significant impairment. Nevertheless, no significant differences emerged in force sense at 20% and 50% of maximal force reproduction (P = .41 and P = .10 for lateral rotator muscles at 20% and 50%, respectively; and P = .20 and P = .09 for medial rotator muscles at 20% and 50%, respectively).

CONCLUSION

Applying a crushed-ice pack to the shoulder for 15 min negatively affected muscle strength and impaired shoulder proprioception by decreasing joint position sense and the threshold for detecting passive movement.