Quadriceps function in anterior cruciate ligament-deficient knees exercising with transcutaneous electrical nerve stimulation and cryotherapy: a randomized controlled study

Objective: To compare strength and quadriceps muscle activation in anterior cruciate ligament-deficient patients who underwent a two-week rehabilitation exercise program using TENS or cryotherapy. Design: Randomized, controlled study. Setting: Clinical research laboratory. Subjects: Thirty patients: 20 males, 10 females, 31.6 (13.0) years, 172.8 (10.0) cm, 75.8 (13.0) kg with diagnosed tear of the anterior cruciate ligament. Interventions: All patients attended four sessions of supervised quadriceps strengthening exercises over two weeks, prior to reconstruction surgery. Patients were randomly allocated ( n = 10/group) to receive exercises alone, exercise while wearing a sensory transcutaneous electrical nerve stimulation (TENS) device on the knee joint for the duration of each daily session, or 20 minutes of knee joint cryotherapy immediately prior to each daily exercise session. Main measures: Normalized knee extension force and quadriceps central activation ratio were measured before and after the first supervised treatment session and within 24 hours of the last session. Results: When accounting for differences in baseline measures, there were no statistically significant group differences immediately following the first exercise session for knee extension force ( P = 0.10) or central activation ratio ( P = 0.30) nor were there statistically significant group differences after the two-week intervention for knee extension force ( P = 0.92) or central activation ratio ( P = 0.94). Effect sizes for the change in knee extension force and central activation ratio after two weeks of therapy were all large. Conclusions: Quadriceps strength and central activation in anterior cruciate ligament deficient patients improved after two weeks of rehabilitaiton exercises, however, there were no significant differences between treatment groups.

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Quadriceps Muscle Function After Exercise in Men and Women With a History of Anterior Cruciate Ligament Reconstruction

Journal of Athletic Training ◽

10.4085/1062-6050-49.3.46 ◽

2014 ◽

Vol 49 (6) ◽

pp. 740-746 ◽

Cited By ~ 9

Author(s):

Christopher M. Kuenze ◽

Jay Hertel ◽

Joseph M. Hart

Keyword(s):

Ligament Reconstruction ◽

Cruciate Ligament ◽

Knee Extension ◽

Maximal Voluntary Isometric Contraction ◽

Men And Women ◽

Central Activation Ratio ◽

Continuous Exercise ◽

History Of ◽

Activation Ratio ◽

Anterior Cruciate

Context : Sex differences in lower extremity neuromuscular function have been reported after anterior cruciate ligament reconstruction (ACLR). Research evidence supports different levels of fatigability in men and women and between patients with ACLR and healthy controls. The influence of sex on the response to continuous exercise in patients with ACLR is not clear. Objective : To compare quadriceps neuromuscular function after exercise between men and women with ACLR. Design : Descriptive laboratory study. Setting : Laboratory. Patients or Other Participants : Twenty-six active volunteers (13 men [50%]: age = 24.1 ± 4.4 years, height = 179.1 ± 9.8 cm, mass = 80.1 ± 9.4 kg, months since surgery = 43.5 ± 37.0; 13 women [50%]: age = 24.2 ± 5.6 years, height = 163.0 ± 5.9 cm, mass = 62.3 ± 8.3 kg, months since surgery = 45.8 ± 42.7) with a history of unilateral primary ACLR at least 6 months earlier. Intervention(s) : Thirty minutes of continuous exercise comprising 5 separate 6-minute cycles, including 5 minutes of uphill walking and 1 minute of body-weight squatting and step-ups. Main Outcome Measure(s) : Normalized knee-extension maximal voluntary isometric contraction torque, quadriceps superimposed-burst torque, and quadriceps central activation ratio before and after exercise. We performed separate 2 (sex: men, women) × 2 (time: preexercise, postexercise) repeated-measures analyses of variance for the 3 variables. Separate, independent-samples t tests were calculated to compare preexercise with postexercise change in all dependent variables between sexes. Results : A significant group-by-time interaction was present for knee-extension torque (P = .04). The percentage reduction in knee-extension maximal voluntary isometric contraction torque (men = 1.94%, women = −10.32%; P = .02) and quadriceps central activation ratio (men = −1.45%, women = −8.69%; P = .03) experienced by men was less than that observed in women. Conclusions : In the presence of quadriceps dysfunction, female participants experienced greater-magnitude reductions in quadriceps function after 30 minutes of exercise than male participants. This indicates a reduced ability to absorb knee-joint loads, which may have significant implications for reinjury and joint osteoarthritis in women after ACLR.

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