Reliability and Validity of a New Eccentric Hamstring Strength Measurement Device.

OBJECTIVE: To investigate the reliability and establish validity of a new eccentric hamstring strength measurement device. DESIGN: A randomized double-crossover trial with intraclass correlation coefficients to analyze the outcomes. Participants attended 4 sessions, 7 days apart. They were randomly allocated into 2 groups. Session 1 was a familiarization session for all participants on the new eccentric hamstring strength measurement device and isokinetic dynamometer. The following 3 sessions were used to measure knee flexor (hamstring) eccentric strength on the isokinetic dynamometer and a further test-retest measurement using the new eccentric hamstring strength measurement device. SETTING: Institute of Technology Carlow, third level educational institution. PARTICIPANTS: Male intercollegiate field-sport players completed the trial (N=19). Participants were 21±2 years, weighed 78.6±4.6 kg, and were 179.6±6.4 cm in height. INTERVENTIONS: N/A. MAIN OUTCOME MEASURES: Peak torque (Nm) was recorded by the isokinetic device, and peak force (N) was recorded by the new eccentric hamstring strength measurement device and used to test for significant interdevice correlations (>0.7). Intraclass correlation coefficients were calculated using the peak force recorded from 2 separate trials of the new eccentric hamstring strength measurement device. RESULTS: High test-retest reliability was observed from the new eccentric hamstring strength measurement device, intraclass coefficient (ICC)=.910 (confidence interval [CI], .76-.96) and .914 (CI, .78-.96) for left and right peak forces, respectively. Typical error of measurement between trials was calculated to be 14.65 and 17.29N for the left and right limbs, respectively. Minimum detectable change (MDC) was also calculated to be 40.62N (MDC%=14.68%) and 39.63N (MDC%=13.31%) for left and right limbs, respectively. The interdevice correlation showed good validity, ICC=.823 (CI, .58-.93) and .840 (CI, .58-.93) for left and right peak torque/forces, respectively. CONCLUSIONS: The new eccentric hamstring strength measurement device is a reliable and valid device that provides an objective measurement of eccentric hamstring strength that may be used in combination with a comprehensive assessment to inform rehabilitation and management.