Strength and Fatigability of the Dominant and Nondominant Hip Abductors

CONTEXT: Contralateral muscular imbalances have been suggested to increase the risk of lower extremity injury. Previous groups have assessed strength of the quadriceps and hamstring muscle groups; however, no previous authors have compared bilateral hip-abductor muscular performance. OBJECTIVE: To examine the strength and fatigability of the hip abductors in the dominant and nondominant legs. DESIGN: Single-group, repeated-measures design. SETTING: Musculoskeletal laboratory. PATIENTS OR OTHER PARTICIPANTS: Forty-two healthy subjects (23 males, 19 females; age = 24.3 +/- 2.7 years, height = 173.4 +/- 9.8 cm, mass = 73.7 +/- 11.6 kg). INTERVENTION(S): Subjects performed three 5-second maximal voluntary isometric contraction (MVIC) trials of the hip abductors with the dominant and nondominant legs. Following the maximal strength trials, subjects performed a submaximal (50% of MVIC) 30-second fatigue trial with each leg. MAIN OUTCOME MEASURE(S): Peak torque (PT) was recorded from each MVIC trial. Surface electromyography was used to record muscle activity during the fatigue trials. Power spectral analysis was used to determine the median frequency of each 0.512-second portion of the fatigue trials. Median frequencies were plotted against time, and linear regression was used to determine the median frequency slope (MF(slope)). Data were analyzed using 2-tailed, paired t tests. RESULTS: Hip-abduction PT of the dominant leg (81.0 +/- 23.7 Nm) was significantly larger than that of the nondominant leg (76.1 +/- 9.9 Nm, P = 0.02). There was no difference in MF(slope) between the dominant (-0.37 +/- 0.29) and nondominant limbs (-0.35 +/- 0.34, P = 0.84). The PT and MF(slope) were not significantly correlated (r = -0.07, P = 0.53). CONCLUSIONS: Hip-abduction strength differences exist between the dominant and nondominant legs. Measures of strength and fatigability were poorly related; therefore, clinicians may opt to assess hip strength and fatigability independent of each another