Muscle Synergies in Single-Leg Hops: Neuromuscular Adaptations for Increased Hop Distance

This study investigated differences in muscle synergies in the trunk and lower limbs during single-leg hops at 30% (SLH30) and 100% (SLH100) of maximum distance to understand the neuromechanical mechanisms underlying longer hop distances. Unilateral surface EMG data were collected from 16 muscle groups in the trunk and lower limbs during both SLH30 and SLH100 in 10 healthy males. Nonnegative matrix factorization was used to extract muscle synergies. The number of muscle synergies in SLH100 was significantly higher than in SLH30 (P = .0078, effect size = 1.28), with median values of 4.0 (3.0-5.0) for SLH30 and 5.0 (4.0-6.0) for SLH100. We identified 4 shared muscle synergies between SLH30 and SLH100, signifying a foundational neuromuscular control strategy. In addition, muscle synergies specific to SLH100 demonstrated the involvement of abdominal muscles and hip and ankle extensor muscles, highlighting their contributions to achieving longer hopping distances. Interventions aimed at enhancing SLH performance for return to sport may benefit from incorporating exercises targeting these synergy patterns. However, it should be noted that SLH100 synergies primarily involved nonknee muscles, warranting caution when using SLH as an indicator of knee function as improvements in hop distance may not directly reflect knee-specific recovery.