Force Production and Neuromuscular Function in Bilateral Movements among Young Females at Low and High Speeds

Abstract

The bilateral limb deficit (BLD) describes the difference in maximal or near maximal force generating capacity of muscles when they are contracted alone or in combination with the contralateral muscles. A deficit occurs when the summed unilateral force is greater than the bilateral force. This study examined the presence of the BLD in young, female figure skaters (n= 8, mean age = 15 ± 1.2 years, mean height =1.67 ± 0.05 m, mean weight = 58.3 ± 5.8 kg) and the influence of speed of contraction and the resulting muscle activity. Torque and myoelectric signal (MES) data were collected from the quadriceps (vastus lateralis) and hamstrings (biceps femoris) during maximal unilateral and bilateral isokinetic knee extensions and flexions at 45(/s and 180(/s. It was found that a BLD exists in these individuals and is similar across both knee extension (BLR₄₅ = 74.5 ± 18.8 %, BLR₁₈₀ = 73.6 ± 9.8%) and flexion (BLR₄₅ = 76.2 ± 10.2 %, BLR₁₈₀ = 74.0 ± 14.4%) and did not differ due to the speed of the contraction. In addition, the MES data showed no difference between bilateral and total unilateral isokinetic knee extensions and flexions. This work found that even in young, athletic females the BLD exists, that it does not depend on the speed of contraction. Furthermore, the data did not detect any MES changes between the bilateral and unilateral conditions that may be causing this deficit. It is important to note, however, that only one muscle of each group (quadriceps and hamstrings) was investigated.