BACKGROUND: Swimming biomechanics still explains propulsion as the hands and feet 'pushing water backwards'. However, years of flow visualisation have revealed a different story. During a cycle, the hand does not propel the body by pushing a compact mass of water. Instead, it continuously modifies the surrounding flow, creating pressure gradients, fluid accelerations and vortical structures. These evolving flow structures redistribute momentum and mechanical energy throughout the surrounding water. Consequently, the hydrodynamic force measured at a particular instant only represents one aspect of the interaction. A complete physical description must also account for the transient storage, convective transport, and dissipation of mechanical energy within the flow field generated by the swimmer. We therefore describe human aquatic propulsion as an energy-momentum continuum and argue that the force-based and continuum concepts are complementary rather than competing. METHODS In a conceptual, conference-length format, the case is built in three linked steps — "Bridging the Gap", "Decoding the Mechanics of Speed", and "Beyond Force" — explained in an illustration in each case. The reasoning rests on the Navier-Stokes equations, on global energy and momentum balances, on a Helmholtz decomposition of the flow, and on a BIV-CFD validation chain; derivations are kept to a minimum. RESULTS: The framework redefines the single force value per cycle in terms of power flow (in watts), energy turnover per cycle, momentum transfer and work cycles. It explains why the Strouhal number determines which mechanism dominates in each body segment, yielding quantities that can be used by coaches and equipment designers. CONCLUSIONS: "Beyond force" means thinking past it by putting energy, momentum and vortices at the centre, while keeping what kinematics has already taught us.
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