Interday reliability of peak muscular power outputs on an isotonic dynamometer and assessment of active trunk control using the chop and lift tests.

CONTEXT Assessment techniques used to measure functional tasks involving active trunk control are restricted to linear movements that lack the explosive movements and dynamic tasks associated with activities of daily living and sport. Reliable clinical methods used to assess the diagonal and ballistic movements about the trunk are lacking. OBJECTIVE To assess the interday reliability of peak muscular power outputs while participants performed diagonal chop and lift tests and maintained a stable trunk. DESIGN Controlled laboratory study. SETTING University research laboratory. PATIENTS OR OTHER PARTICIPANTS Eighteen healthy individuals (10 men and 8 women; age  =  32 ± 11 years, height  =  168 ± 12 cm, mass  =  80 ± 19 kg) from the general population participated. INTERVENTION(S) Participants performed 2 power tests (chop, lift) using an isotonic dynamometer and 3 endurance tests (Biering-Sørensen, side-plank left, side-plank right) to assess active trunk control. Testing was performed on 3 different days separated by at least 1 week. Reliability was compared between days 1 and 2 and between days 2 and 3. Correlations between the power and endurance tests were evaluated to determine the degree of similarity. MAIN OUTCOME MEASURE(S) Peak muscular power outputs (watts) derived from a 1-repetition maximum protocol for the chop and lift tests were collected for both the right and left sides. RESULTS Intraclass correlation coefficients for peak muscular power were highly reliable for the chop (range, 0.87-0.98), lift (range, 0.83-0.96), and endurance (range, 0.80-0.98) tests between test sessions. The correlations between the power assessments and the Biering-Sørensen test (r range, -0.008 to 0.017) were low. The side-plank tests were moderately correlated with the chop (r range, 0.528-0.590) and the lift (r range, 0.359-0.467) tests. CONCLUSIONS The diagonal chop and lift power protocol generated reliable data and appears to be a dynamic test that simulates functional tasks, which require dynamic trunk control.