Assessing hip abduction and adduction strength: can greater segmental fixation enhance the reproducibility?

OBJECTIVE

To improve the reproducibility of testing hip abduction and adduction using an isokinetic dynamometer by a novel testing protocol.

DESIGN

Test-retest design.

SETTING

Biodynamics laboratory.

PARTICIPANTS

Fifteen healthy subjects (9 men, 6 women; age, 22.4+/-0.5 y) were recruited.

INTERVENTIONS

Two setups were compared: the first according to manufacturer's guidelines (setup A) and the second a novel setup incorporating pelvic fixation (setup B). Setups A and B were performed in a random order. Both setups included the same battery of isokinetic (30 degrees/s, 60 degrees/s) and isometric tests, and were repeated 1 week later.

MAIN OUTCOME MEASURES

The peak torque for each abduction and adduction exercise was noted and pelvic motion during testing was recorded.

RESULTS

Setup B significantly (P<.05) reduced transverse pelvic rotation by between 7.5 degrees and 8.0 degrees dependent on test speed. Mean differences for reproducibility of peak torque, ranged from 0.8 to 11.7 Nm. The coefficients of repeatability of both setups were similar, ranging from 21.4 to 56.3 Nm across isokinetic exercises. A similar observation was noted for isometric exercises, with the differences between the coefficients of repeatability ranging from 18.6 to 40.0 Nm.

CONCLUSIONS

Reducing pelvic rotation does not enhance reproducibility of the system and is not related to torque production. Further research is required to determine the optimal test setup.