Associations Between Selected Biological Features and Absolute and Relative Swimming Performance of Prepubescent Boys Over a 3‐Year Swimming Training Program: A Longitudinal Study

The study aimed to investigate the effect of 3-year swimming training on selected biological variables in prepubescent male swimmers and to determine the best predictors of absolute (VS(a)) and relative (VS(r)) swimming velocity for 50 m and 400 m front crawl. Twenty-one 10-year old boys subjected to endurance swimming training (4 x 70 min per week) and 18 boys consisting a control group were assessed semi-annually for basic anthropometric and respiratory characteristics, breath-hold time (BHT), VO(2max), leg explosiveness (HJ), and abdominal strength endurance (ASE). After three years of training, BHT (p < 0.001), VO(2max) (p < 0.01), HJ (p < 0.01) and ASE (p < 0.01) were greater in the swimmers than in the controls. VS(a) and VS(r) expressed as a percentage of baseline velocity increased more for the 50 m than for the 400 m distance (p < 0.001 and p < 0.01, respectively). The 50 m VS(a) and VS(r) positively correlated with those obtained for the distance of 400 m (in both cases p < 0.001). Baseline VS(a) was negatively correlated with the increase in absolute swimming velocity for both distances (50 m: r = -0.684, p < 0.001 and 400 m: r = -0.673, p < 0.001). The best predictors of VS(a) for 50 m and 400 m front crawl were HJ (r(2) = 0.388; p < 0.001) and VO(2max) (r(2) = 0.333; p < 0.001), respectively. The key predictors of VS(r) for both distances were age (50 m: r(2) = 0.340, p < 0.001 and 400 m: r(2) = 0.207, p < 0.001) and, after excluding it from analysis, HJ (50 m: r(2) = 0.176, p < 0.001 and 400 m: r(2) = 0.104, p < 0.001). These results suggest that regardless of prepubescent boys’ initial abilities and exercise capacity, improvement in their swimming performance mainly depends on increases in power and neuromuscular coordination.