To study the variability in stroking parameters between and within laps and individuals during competitions, we compared and modeled the changes of speed, stroke rate, and stroke length in 32 top-level male and female swimmers over 4 laps (L1–L4) in 200-m freestyle events using video-derived 2-dimensional direct linear transformation. For the whole group, speed was greater in L1, with significant decreases across L2, L3, and L4 (1.80 ± 0.10 vs 1.73 ± 0.08; 1.69 ± 0.09; 1.66 ± 0.09 · s−1, P < .05). This variability was attributed to a decrease in stroke length (L2: 2.43 ± 0.19 vs L4: 2.20 ± 0.13 m, P < .05) and an increase in stroke rate (L2: 42.8 ± 2.6 vs L4: 45.4 ± 2.3 stroke · min−1, P < .05). The coefficient of variation and the biological coefficient of variation in speed were greater for male versus female (3.9 ± 0.7 vs 3.1 ± 0.7; 2.9 ± 1.0 vs 2.6 ± 0.7, P < .05) and higher in L1 versus L2 (3.9 ± 1.3 vs 3.1 ± 0.1; 2.9 ± 0.9 vs 2.3 ± 0.7, P < .05). Intra-lap speed values were best represented by a cubic (n = 38), then linear (n = 37) and quadratic model (n = 8). The cubic fit was more frequent for males (43.8%) than females (15.6%), suggesting greater capacity to generate higher acceleration after the turn. The various stroking parameters managements within lap suggest that each swimmer adapts his/her behavior to the race constraints.
David Simbaña Escobar, Philippe Hellard, David B. Pyne and Ludovic Seifert
Andrew A. Dingley, David B. Pyne and Brendan Burkett
Disabilities in Paralympic swimming could impact a swimmer’s ability to execute an effective swim-start. We examined how swim-start performance differed between severity and type of physical disability. Swim-starts were measured in 55 elite Paralympic swimmers from eight different Paralympic classes; S14, S13, S10-S6, S3 grouped as no- (classes S13 & S14), low- (S9 & S10), mid- (S7 & S8) or high- (≤ S6) severity of physical disability and also by type of physical disability (upper, lower, and palsy) to provide meaningful comparisons. The swimmer’s competitive level was determined by the international point score (IPS). Swimmers with no physical disability were significantly faster in most swim-start phases compared with those with physical disabilities, as were swimmers with low-severity disabilities compared with the mid- and high-severity groups. Block velocity was highly negatively correlated (r = –0.57 to –0.86) with 15-m swimming time for all groups except high-severity disabilities. Free-swim velocity is a priority area for improving swim-starts for swimmers regardless of disability, given large correlations between this measure and IPS. Swimmers with lower body or high-severity disabilities spent a smaller percentage of time overall in the underwater phase. Assessment of four specific phases of the swim-start highlight distinctive priorities for coaches working with Paralympic swimmers in an applied biomechanical manner.