Speed-Dependent Upper-Limb Control Asymmetries in Backstroke Swimming during Psycho-Neuro-Motor Training

Introduction. Upper-limb asymmetries in backstroke swimming can affect stroke efficiency and performance, yet their dynamics with respect to execution speed are not fully understood. This study extends previous research on lower-limb asymmetries to investigate speed-dependent upper-limb asymmetries and the potential of simulator-based training to improve interlimb coordination. Materials and Methods. An elite 100 m backstroke swimmer performed two sessions on the "C.S.N. Simulator for Water Sports†(C.S.N. Simulator), executing 30 repetitions per arm at progressive motor-assisted velocities (0, 0.5, 1.2 m/s) with constant brake intensity (15%). Force–position data were recorded in real time across catch, traction, and push phases. Results. At lower speeds, the left arm dominated during catch and traction, while higher speeds increased variability and shifted dominance toward the right arm in the push phase. Inter-session improvements demonstrated reduced asymmetry and more balanced force application, though variability remained at higher velocities. Conclusions. Upper-limb asymmetries are speed- and phase-dependent. Simulator- based training with real-time feedback can enhance coordination, reduce asymmetry, and potentially improve performance, complementing prior findings on lower-limb asymmetries