Factors affecting the variability of the torque curves at isokinetic trunk strength testing.

OBJECTIVES: To evaluate the relation between variability of the torque curves and factors such as age, gender, measurement speeds, and period from low back pain (LBP) onset at isokinetic trunk strength testing.
DESIGN: Observational.
SETTING: Hospital. PATIENTS: One hundred forty-three consecutive LBP patients (acute, subacute, and chronic) who received physical therapy, and 200 healthy volunteer subjects. MAIN OUTCOME MEASURES: The variability of the torque curves is an indicator of consistency of effort, and was measured as the coefficient of variance (CV) at different measurement speeds in isokinetic trunk flexion/extension strength testing.
RESULTS: The CV was lower in men than in women at the faster measurement speed. LBP patients had higher CV values than healthy subjects. The CV was different according to gender and measurement speed, but not different according to age and periods from LBP onset.
CONCLUSION: The CV was affected by measurement speed and gender, but not by age or period from LBP onset. Because the CV was higher in LBP patients than in healthy subjects, this value may be usable as an adjunctive index of LBP.