Correlations of isokinetic and psychophysical back lift and static back extensor endurance tests in men.

Isokinetic lift, psychophysical lift, and static back endurance tests are among the most widely used measurements of muscle function for determining risk for, and recovery from, back problems. After determining test repeatability we examined the degree of association between these test measures in 100 men selected to represent a variety of occupations and lifestyles. Isokinetic lifting had low correlations with test results for psychophysical lifting (r = 0.28) and static back endurance (r = 0.24). Static back endurance and psychophysical lift test results were not at all correlated (r = 0.03). RELEVANCE--:Muscle function measurements for back problems are sometimes arbitrarily selected due to health practioners' beliefs and preferences or practical reasons such as the availability of equipment. Yet little is known about the associations of these tests with one another or with anthropometric factors. The data presented in this study document that isokinetic lift, psychophysical lift, and static back endurance tests appear to measure very different aspects of muscle function, and comparing studies using these different test methods should be approached with these low inter-test correlations in mind.