Development Of A Single-Session Assessment Protocol For Isokinetic Testing Of The Hamstrings/Quadriceps Strength Ratio

BACKGROUND: The ratio of hamstring to quadriceps strength (H/Q), from isokinetic testing, is often used to guide training or rehabilitation.OBJECTIVES: The primary objective was to develop an assessment protocol that produces reproducible H/Q data in a single testing session.METHODS: Twenty-four healthy subjects, 16 women and 8 men, were tested using a reliability study design (2 sessions, 5 repetitions). The main outcome measure was the dynamic control ratio at 60 degrees/s (DCR60). Testing was also done at 120 degrees/s, and concentrically at 180 degrees/s. Generalizability theory was used to determine the reliability (phi) coefficient and the minimal detectable change MDC, and to extrapolate the data to develop an optimal assessment protocol, ideally using data from only one session.RESULTS: Single-session DCR60 data were reproducible (phi coefficient = 0.868, MDC95 = 0.144) using 5 repetitions, excluding the first repetition from the average. Values were improved by averaging over multiple sessions and repetitions, although little was gained from more than 2 sessions or 5 repetitions. Comparable results were found for testing at 120 degrees/s.CONCLUSIONS: Reproducible DCR60 values may be derived from a single testing session of the hamstrings (in eccentric mode) and the quadriceps (in concentric mode). We recommend collecting five repetitions, and averaging the data for repetitions 2-5.