Additional shoulder roll may not augment the simulation of freestyle stroke kinematics on a swim bench

The swim bench is an isokinetic ergometer designed to replicate the underwater pull of the freestyle stroke for swimming training. However, limited literature addresses the biomechanical fidelity of the swim bench and specific changes to a swimmer's kinematics with the addition of a torso rotation setting. The aim of this study was to assess the influence of swim bench rotation settings on freestyle stroke kinematics and evaluate the differences with pre-existing in-water kinematic data. Few kinematic differences were noted between the swim bench settings. However, both swim bench settings produced a shorter entry and longer pull, push, and recovery stroke cycle phase durations (p < 0.0001), shorter stroke length (p = 0.0002), narrower mean peak stroke width (p < 0.0001), and restricted total shoulder roll (rotating: 37°± 28, fixed: 33° ± 26, in-water: 96°± 7.0, p < 0.0001) compared to the in-water data. The addition of a rotating setting to the swim bench may not substantially supplement simulation of the underwater freestyle pull. Further, the movement performed on the swim bench may not be sufficiently sport specific to allow training and research findings to be extrapolated to the pool. This study provides novel data for coaches and researchers regarding the potential utility of the swim bench for both training and research applications.