Determination of Functional Strength Imbalance of the Lower Extremities

Abstract

The purposes of this study were (a) to determine whether a significant strength imbalance existed between the left and right or dominant (D) and nondominant (ND) legs and (b) to investigate possible correlations among various unilateral and bilateral closed kinetic chain tests, including a field test, and traditional isokinetic dynamometry used to determine strength imbalance. Fourteen Division I collegiate women softball players (20.2 +/- 1.4 years) volunteered to undergo measures of average peak torque for isokinetic flexion and extension at 60 degrees .s(-1) and 240 degrees .s(-1); in addition, measures of peak and average force of each leg during parallel back squat, 2-legged vertical jump, and single-leg vertical jump and performance in a 5-hop test were examined. Significant differences of between 4.2% and 16.0% were evident for all measures except for average force during single-leg vertical jump between the D and ND limbs, thus revealing a significant strength imbalance. The 5-hop test revealed a significant difference between D and ND limbs and showed a moderate correlation with more sophisticated laboratory tests, suggesting a potential use as a field test for the identification of strength imbalance. The results of this study indicate that a significant strength imbalance can exist even in collegiate level athletes, and future research should be conducted to determine how detrimental these imbalances could be in terms of peak performance for athletes, as well as the implications for injury risk.

Asymmetries in single and triple hop are not detrimental to change of direction speed

“…The present study revealed trivial non-significant differences right and left limbs in hop performance, however small significant differences were found between D and ND limbs (Table 1), consistent with previous research in university, 12 netball, 13 and softball athletes 27 . Interestingly, the D hopping limb did not always correspond to throwing hand or kicking leg dominance as illustrated in Figures 1; similar to corroborative research.…”

“…12 This could be due to specific sporting demands which may result in imbalances between limbs, such as the support limb during kicking a football or decelerating limb during a batting stroke and cricket bowl. 27,32 Contrary to expectations, hop imbalances had no detrimental impact on turning and cutting performance (Table 2) which supports the only other study to investigate the impact of between limb asymmetries in unilateral hops on CODS perfor- mance reporting no effect. 10 This outcome is in contrast to previous research which has shown imbalances in unilateral drop jump height and reactive strength associated with slower cutting performance.…”

“…27 Limb dominance was defined as the limb that produced the furthest hop or faster CODS performance. 12,23 Asymmetry index for D and ND limbs was calculated by the formulae (dominant leg -non dominant leg/ dominant leg × 100) for hops and CODS performance.…”

Isometric force production symmetry and jumping performance in collegiate athletes

“…Concerning a sport such as baseball or softball, a player may throw or hit with the same side of their body possibly leading to altered ranges of motion and strength asymmetries. [1][2][3] Other sports may require the players to utilize both sides of their body equally, but lengthy playing careers in any sport may result in changes in the range of motion, force producing capabilities, and overall symmetry of one's body.…”

Influência da fadiga unilateral de membro inferior sobre o salto vertical bilateral

“…However, it seems that fatigue of only one of the limbs alters this common command and dissociating the command for both limbs (1) . In practical terms, training, as well as the familiarization to tasks, may reduce the bilateral strength deficit minimizing the asymmetry, especially at fatiguing conditions, in which the control dissociation may modify the overload between limbs, since tasks which present asymmetry between limbs are more prone to injuries during physical performance (30)(31)(32)(33)(34)(35)(36) .…”