Abstract
PurposeThis study investigated the relationship between hand kinematics, hand hydrodynamic pressure distribution and hand propulsive force when swimming the front crawl with maximum effort.MethodsTwenty-four male swimmers participated in the study, and the competition levels ranged from regional to national finals. The trials consisted of three 20 m front crawl swims with apnea and maximal effort, one of which was selected for analysis. Six small pressure sensors were attached to each hand to measure the hydrodynamic pressure distribution in the hands, 15 motion capture cameras were placed in the water to obtain the actual coordinates of the hands.ResultsMean swimming velocity was positively correlated with hand speed (r = 0.881), propulsive force (r = 0.751) and pressure force (r = 0.687). Pressure on the dorsum of the hand showed very high and high negative correlations with hand speed (r = −0.720), propulsive force (r = −0.656) and mean swimming velocity (r = −0.676). On the contrary, palm pressure did not correlate with hand speed and mean swimming velocity. Still, it showed positive correlations with propulsive force (r = 0.512), pressure force (r = 0.736) and angle of attack (r = 0.471). Comparing the absolute values of the mean pressure on the palm and the dorsum of the hand, the mean pressure on the dorsum was significantly higher and had a larger effect size (d = 3.71).ConclusionIt is suggested that higher hand speed resulted in a more significant decrease in dorsum pressure (absolute value greater than palm pressure), increasing the hand propulsive force and improving mean swimming velocity.
Highlights
Two factors determine the swimming velocity: propulsion and drag force
The results showed that advanced swimmers exhibited more significant hand propulsive force, and a higher competitive level was associated with more substantial hand propulsive force
This study aimed to identify the factors responsible for high hand propulsive force in swimmers who can reach high swimming velocity and assess the influence of hand hydrodynamic pressure and hand kinematics
Summary
Two factors determine the swimming velocity: propulsion and drag force. When the swimming velocity is constant, the mean propulsion and the mean drag are the same (van der Vaart et al, 1987). Researchers have established indirect methods to estimate these forces, such as the MADsystem (Hollander et al, 1986), velocity perturbation method (Kolmogorov and Duplishcheva, 1992), assisted towing method (Formosa et al, 2012), MRT (measured values of residual thrust) method (Narita et al, 2017). These methods enable researchers to estimate drag (and propulsion, assuming the swimmer maintains a constant velocity ignoring force and velocity fluctuations within a stroke cycle) acting on the whole body but do not provide information on the sources of the total forces
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