This study aimed to compare lower limb muscle strength and performance capacity between the dominant and non-dominant legs of healthy males who participate in sports where non-contact injuries are common.
The participants were sixteen healthy males who had been playing a specific sport for at least four years at the time of measurement. The leg on the side that kicked the ball was defined as the dominant leg, and the axis leg was defined the non-dominant leg. Five muscle strengths were assessed the maximum isometric strength: the hip flexors, hip extensors, hip abductors, knee flexors, and knee extensors. Six performance tests were used in this study: Single Leg Hop Test (SLHT), Cross Over Hop Test (COHT), Side Hop Test (SHT), Counter Movement Jump Test (CMJT), 180° Change of Direction Test (180CDT), and 90° Change of Direction Test (90CDT). The LSI was calculated as (non-dominant leg/dominant leg) × 100.
Significant differences were observed between the dominant and non-dominant legs in the hip flexor, hip abductor, and knee extensor muscles, all of which were significantly higher in the dominant leg. The LSI was as low as 88% for the hip flexors, whereas the strengths of the other muscles ranged from 91% to 98%.
Significant differences were observed between COHT and 90CDT when comparing the dominant and non-dominant legs. The dominant leg showed a longer jump distance in the COHT, whereas the non-dominant leg had a shorter measurement time in the 90CDT. The LSI ranged from 96% to 103% for all the tests.
This study found a significant difference between the dominant and non-dominant legs in the COHT and 90CDT, even when both lower limbs were healthy. This suggests that the decision to return to sports should consider not only the LSI between the healthy and affected limbs but also whether the affected limb is the dominant or non-dominant leg.
This study will give more credibility to the criteria of return to sports after ACL reconstruction surgery.
Lower-limb asymmetry
Dominant Leg
