Abstract
The aim of this study was to assess the reliability of isokinetic and ISO knee extensor and flexor muscle strength when using the REV9000 (Technogym) isokinetic dynamometer. Moreover, the reliability of several strength imbalance indices and bilateral ratios were also examined. Twenty-four physically active healthy subjects (age 23±3 years) underwent three testing sessions, two on the same day and a third, 7 days later. All sessions proceeded in the same order: five concentric contractions at 60ºs-1 followed by an isometric contraction (5 seconds) and five eccentric contractions (60ºs-1). The results of this study showed a high reproducibility in eccentric (0.95-0.97), concentric (0.95-0.96) and isometric (0.93-0.96), isokinetic strength for knee extensor and flexor muscles, thus indicating that the REV9000 isokinetic dynamometer can be used in future sports performance studies. A low-to-moderate reliability was found in the isokinetic strength bilateral ratios while the Hamstring:Quadricep concentric ratio showed moderate reliability. The highest reliability (>0.90) was observed in the dynamic control ratio (Hamstring eccentric:Quadricep concentric) which consequently confirms that it is a more valid indicator for imbalanced reciprocal parameters and can be used in rehabilitation and sports medicine.
Highlights
The use of isokinetic dynamometers to assess muscle function has become progressively popular in sport, research and clinical settings
Procedures All sessions were carried out at the same time (4p.m.), approximately 3 hours after lunch. They were preceded by a 10 minute warm-up on an ergocycle (70rpm at 50 W) and stretching exercises where subjects sat with their thighs at an angle of 85o to the trunk
The highest and lowest intraclass correlation coefficient (ICC) for peak torque was found in the eccentric contraction for the left knee flexor (0.97) and in ISO contraction of the left knee extensor (0.93), respectively
Summary
The use of isokinetic dynamometers to assess muscle function has become progressively popular in sport, research and clinical settings. Isokinetic devices assess joint and muscle maximal concentric (CON), eccentric (ECC) and isometric (ISO) strength under constant velocities throughout the whole range of motion. Several studies have used isokinetic dynamometers to assess ISO and dynamic (CON and ECC) strength of the knee extensor and flexor muscles (Bardis et al, 2004; Cotte and Ferret, 2003). Isokinetic devices are used in rehabilitation and sports medicine to assess risk factors such as low strength muscles and in developing rehabilitation programmes for knee and hamstring injuries or imbalances (Croisier, 2004; Dauty et al, 2003; Impellizzeri et al, 2008; Kannus, 1994). There are numerous factors that can influence the measurement of
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