Core muscle strength can be reliably measured using a novel isokinetic device: An intra-observer study

Abstract

BACKGROUND: Core strength is an important aspect of physical fitness. A dynamometer was developed to measure isokinetic core muscle strength in multiple planes of motion. Establishing the reliability is needed before it can be used in practice. OBJECTIVE: Examine the intra-observer reliability of a trunk isokinetic dynamometer. METHODS: 31 participants were recruited. Tests were performed twice with an interval of 5–9 days by the same observer. Testing included rotation, flexion/extension and lateral flexion at speeds of 90∘/s and 60∘/s. The main outcome measure was peak torque (PT). The secondary outcomes included peak torque angle (PTA), time to peak torque (TTPT) and compensatory torques (CompTQ). The intra-observer reliability was investigated using intraclass correlation coefficients (ICC). RESULTS: Peak torque reliability was good to excellent (ICC = 0.70–0.91), whereas the reliability of the PTA (ICC =-0.04–0.56) and TTPT (ICC = 0.01–0.68) were poor to moderate. CompTQ reliability was moderate to good (ICC = 0.20–0.88). CONCLUSIONS: The intra-observer reliability of the isokinetic measurement of core strength peak torque was good. The secondary outcomes peak torque angle and time to peak torque were less reliable and the compensatory torques showed moderate to good reliability. This isokinetic dynamometer could have useful applications in the field of sports medicine and rehabilitation.

Strength Assessment of Trunk Rotator Muscles: A Multicenter Reliability Study

“…Comparing these reliability results is difficult due to the novelty of both the test and the device. Regarding the evaluation of TRS in isokinetic devices, these results agree with previous studies where the TRS was evaluated at two isokinetic velocities, obtaining similar reliability values (ICC = 0.80-0.90; CV = 11-17%), showing better absolute and relative reliability values to the lowest velocity (60 • ) [22]. In another study that evaluated TRS in an isometric mode, the coefficient of variation value was 3.5-4.5% [24].…”

“…However, in many studies that analyze the reliability of TRS, the manifestation taken over the years has been the peak strength, without having studied the behavior of the average strength. In isokinetic devices, the peak strength is almost always taken as a reference [ 22 , 23 ]; however, different studies have analyzed the strength of the trunk with new devices and have shown that the most reliable manifestation is the average strength [ 15 , 16 ].…”