The relationship between load-velocity profiles and 50 m breaststroke performance in national-level male swimmers.

This study investigated the relationships between load-velocity profiling and 50 m breaststroke performance. Twenty-seven male swimmers qualified for the national championship participated and performed a 50 m breaststroke trial with a multicamera system. The total race time (t), forward velocity during surface swimming (v), stroke length, and stroke frequency were obtained from the automatic post-processing of the system. Afterwards, the participants performed semi-tethered swimming with three external loads using a robotic resistance device. The average velocity from three stroke cycles was plotted as a function of the corresponding load. The theoretical maximum velocity (v) and load (L), L normalized to body mass, steepness of the regression line (slope), and active drag (AD) were calculated. The main findings were moderate to large correlations of two 50 m race variables (t and v) with v, L, and AD (t range: = -.444 to = -.619,  = .020 to  = .001), (v range:  = .451 to  = .568,  = .018 to  = .002). This shows the importance of applying maximum propulsive force to achieve high swimming performance and that load-velocity profiling is an indicator of 50 m breaststroke performance. Load-velocity measurements over time can also monitor velocity, strength, and drag-minimizing abilities, explaining performance changes and training effects.