A comparison of isokinetic and functional methods of assessing bilateral strength imbalance

Muscle strength imbalances have been linked with poor agility performance and higher injury risk. Isokinetic dynamometry has been used to investigate such imbalances; however, this method is impractical and inaccessible for most strength and conditioning coaches. The aim of the study was to compare isokinetic dynamometry with functional field tests for assessing bilateral strength imbalance. Thirteen male athletes from various sports (mean+/-SD: age 21+/-1.1 years, height 179.8+/-7.0 cm, body mass 80.8+/-9.7 kg) participated in the study. Knee flexor and extensor strength at 60 degrees.s(-1) was assessed for both limbs with the use of isokinetic dynamometry. Field tests involved seated unilateral leg press, horizontal hop, single-leg vertical and drop jumps. Significant differences (p<0.01) were found when comparing strength dominant (D) and nondominant (ND) limbs for all strength measures, ranging from 4.5% (hop test) to 12.4% (eccentric extension). No significant differences between the right and left limbs were found (p>0.05). No significant relationships between strength D/ND ratios of isokinetic variables and the field tests were evident (p>0.05). The findings provide support for the use of field tests to detect imbalances between lower limbs, but the ultimate choice of test used should depend on the specific strength quality that predominates in the sport.