Isometric and isokinetic testing of core muscles during trunk rotation

Objective To quantify the correlation between isometric and isokinetic tests of core muscles during trunk rotation. Methods The strength of the core muscles of 38 healthy males was measured isometrically and isokinetically ( at 60°/s) during trunk rotation.The left and right peak rotation torque ( LPT,RPT) and the ratio of left to right torque (L/R) were analyzed using correlation and regression analysis and paired t-tests. Results The subjects' LPTs and RPTs were positively correlated ( rL =0.644,P ≤ 0.01 ;rR =0.566,P≤0.01 ) There were significant differences in the L/R ratios determined using the two tests (r=0.663,P≤0.01 ).The regression equations predicting LPT and RPT were yL =22.330 + 0.937x and yR =32.752 +0.847x,respectively.Paired t-tests showed that tL =4.562,P≤0.01 and tR =3.855,P≤0.01 during left or right rotation.There was a significant difference,but there was no significant difference in LPT/RPT. Conclusion Isometric and isokinetic tests of core muscles during trunk rotation give results which are strongly correlated.Either can correctly reflect the maximal strength of core muscles during trunk rotation.Clinicinas may reasonably choose either testing method to assess patients and guide treatment according to the patient's clinical symptoms and the severity of the problem. Key words: Core muscles; Rotation; Isometric contraction; Isokinetic contraction; Strength testing