Transcranial Magnetic Stimulation and Volitional Quadriceps Activation

Abstract

Quadriceps-activation deficits have been reported after meniscectomy. Transcranial magnetic stimulation (TMS) in conjunction with maximal contractions affects quadriceps activation in patients after meniscectomy. To determine the effect of single-pulsed TMS on quadriceps central activation ratio (CAR) in patients after meniscectomy. Randomized controlled clinical trial. University laboratory. Twenty participants who had partial meniscectomy and who had a CAR less than 85% were assigned randomly to the TMS group (7 men, 4 women; age = 38.1 ± 16.2 years, height = 176.8 ± 11.5 cm, mass = 91.8 ± 27.5 kg, postoperative time = 36.7 ± 34.9 weeks) or the control group (7 men, 2 women; age = 38.2 ± 17.5 years, height = 176.5 ± 7.9 cm, mass = 86.2 ± 15.3 kg, postoperative time = 36.6 ± 37.4 weeks). Participants in the experimental group received TMS over the motor cortex that was contralateral to the involved leg and performed 3 maximal quadriceps contractions with the involved leg. The control group performed 3 maximal quadriceps contractions without the TMS. Quadriceps activation was assessed using the CAR, which was measured in 70° of knee flexion at baseline and at 0, 10, 30, and 60 minutes posttest. The CAR was expressed as a percentage of full activation. Differences in CAR were detected over time (F(4,72) = 3.025, P = .02). No interaction (F(4,72) = 1.457, P = .22) or between-groups differences (F(1,18) = 0.096, P = .76) were found for CAR. Moderate CAR effect sizes were found at 10 (Cohen d = 0.54, 95% confidence interval [CI] = -0.33, 1.37) and 60 (Cohen d = 0.50, 95% CI = -0.37, 1.33) minutes in the TMS group compared with CAR at baseline. Strong effect sizes were found for CAR at 10 (Cohen d = 0.82, 95% CI = -0.13, 1.7) and 60 (Cohen d = 1.06, 95% CI = 0.08, 1.95) minutes in the TMS group when comparing percentage change scores between groups. No differences in CAR were found between groups at selected points within a 60-minute time frame, yet moderate to strong effect sizes for CAR were found at 10 and 60 minutes in the TMS group, indicating increased activation after TMS.