Validity of isokinetic testing for previous hamstring injury detection in soccer players

The purpose of this study was to determine the most accurate isokinetic testing method, either concentric/concentric or concentric/eccentric, for the detection of previous hamstring injury. twenty-one male semi-professional soccer players were recruited from premier divisions of the Sunday football league and the Isthmian league division one in England and examined on a Cybex Norm isokinetic dynamometer. Eleven players had suffered previous hamstring injury whilst ten players that had never suffered hamstring injury formed the control group. For each group the following ratios were determined: unilaterally: concentric hamstring/concentric quadriceps, eccentric hamstring/concentric quadriceps; bilaterally: concentric hamstring, eccentric hamstring and concentric quadriceps at both 60°/s and 120°/s. The Area Under the Curve (AUC) of Receiver Operating Characteristics (ROC) provided a summary measure of the validity of each test. Significant differences between injury and non-injury groups were found for the bilateral concentric hamstring ratio measured with a concentric/concentric testing method at 60°/s (AUC = 0.773, P < 0.05). All other ratios rendered non-significant AUC values. In addition, non-significant AUC were recorded for all ratios measured at 120°/s. Therefore, these observations suggested that the concentric/concentric testing method may be suitable for detecting previous hamstring injury. In addition, these findings suggested that a lower speed (60°/s) should be utilized for the muscular strength analysis of soccer players suffering from hamstring injury.