Physical Therapy

Document Type


Publication Source

Journal of Orthopaedic Surgery. Volume 27, Issue 1, Pages 1-8.

Publication Date



Purpose: To determine the effects of cryotherapy on quadriceps electromyographic (EMG) activity and isometric strength in early postoperative knee surgery patients.

Methods: Twenty-two volunteers with recent knee surgeries were included. EMG readings of the vastus medialis (VM), rectus femoris (RF), and vastus lateralis (VL) from the surgical leg were collected during a maximal voluntary quadriceps setting (QS) activity. Maximum isometric knee extension force measurements were also recorded. Subjects were randomly assigned to receive an ice bag or a sham room-temperature bag to the front of their postsurgical knee for 20 min. After treatment, the subjects repeated the above mentioned maximum QS and isometric knee extension force measurements. The subjects returned 24 h later to conduct the same test protocol but received the treatment (ice or sham) not applied during their first test session.

Results: A 38% increase in VM EMG activity during QS and a 30% increase in maximum isometric knee extension strength were found after cryotherapy treatment. No significant differences were found in RF or VL EMG activity during QS after cryotherapy. No significant differences were found in any measurements after the sham treatment.

Conclusion: Clinicians should consider applying ice to knee joints prior to exercise for patients following knee surgery with inhibited quadriceps.


electromyography, ice, quadriceps inhibition, rehabilitation




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