Quadriceps muscle function after rehabilitation with cryotherapy in patients with anterior cruciate ligament reconstruction.
Hart JM, Kuenze CM, Diduch DR and Ingersoll CD. J Athl Training. [Epub Ahead of Print].
Take Home Message: Among knees with a history of anterior cruciate ligament (ACL) reconstruction and chronic quadriceps dysfunction, the application of cryotherapy prior to performing exercises may help mitigate arthrogenic muscle inhibition and improve muscle function.
Following ACL reconstruction, patients often suffer from persistent quadriceps weakness potentially caused by arthrogenic muscle inhibition. If clinicians could reduce arthrogenic muscle inhibition then patients may be able to increase quadriceps strength. Therefore, Hart and colleagues compared quadriceps muscle function in patients treated with cryotherapy, exercise, or both. The authors included 30 participants who had undergone ACL reconstruction at least 6 months prior to the study, and were cleared for physical activity by their physician. At baseline, the authors measured the patients’ quadriceps activation and quadriceps Hoffmann reflex. To assess quadriceps activation, patients sat and performed 2 to 3 maximum voluntary isometric contractions of the quadriceps. As their torque reached plateau, the researchers applied an electrical stimulus to increase torque above the maximum voluntary isometric contraction value. The central activation ratio was defined as the torque generated by a maximum voluntary isometric contraction divided by the electrically stimulated activation. The authors measured Quadriceps Hoffmann reflex by applying a short electrical stimuli to the patient’s femoral nerves (electrode placed in the inguinal fold) in a supine position. After baseline testing, researchers randomized the participants into 1 of 3 treatment groups for a 2-week intervention. Participants in the cryotherapy group applied 2 ice bags to the anterior and posterior sides of the knee for 20 minutes everyday. Participants in the exercise group, performed a 1-hour long, progressive exercise program daily. Participants randomized to the combination group performed cryotherapy for 20 minutes followed by the same exercise program as performed by the exercise group. All participants attended four supervised treatment sessions during the 2-week period. Patients’ quadriceps activation and Hoffmann reflex were measured following the 2-week intervention. Overall there were no significant differences between any of the treatment groups for any variables. However, there was trends indicating that participants who received both cryotherapy and exercise increased knee extension torque while participants in the cryotherapy group or exercise group did not.
Overall, the current study provides preliminary support for the use of cryotherapy prior to exercise in patients who have undergone ACL reconstruction and who have chronic quadriceps muscle dysfunction. The results of this study should be particularly interesting to clinicians as it shows how cryotherapy can be beneficial in mitigating arthrogenic muscle inhibition as well as pain. By using cryotherapy prior to the exercises, clinicians could reduce the muscle inhibition during the exercises and maximize the benefits of an exercise program. More research will be needed to determine if cryotherapy prior to exercises is also effective among patients with different injuries as well as varying levels of pre-injury activity, amounts of quadriceps inhibition, times since injury, ages, and delays between surgery and intervention. Until this can be done however, clinicians should use cryotherapy to treat pain and possibly muscle inhibition throughout the rehabilitation process.
Questions for Discussion: Have you used cryotherapy prior to exercise to help improve quadriceps activation? When do you use cryotherapy?
Written by: Kyle Harris
Reviewed by: Jeffrey Driban