# Kinematic Determinants of the Swimming Push Start in Competitive Swimmers
## 3 Results  
The times to 10 m of national level swimmers during the push start ranged from 4.5 s to 5.3 s, regardless of gender and stroke. Overall, male swimmers obtained faster times than females (gender effect: F\({}_{1}\) = 7.40, \(p\) < 0.01, \(\eta^{2}\) = 0.06) and differences were also observed due to strokes (stroke effect: F\({}_{2}\) = 4.77, \(p\) < 0.01, \(\eta^{2}\) = 0.08), with backstroke start times being longer than the butterfly (\(p\) = 0.004) and front-crawl (\(p\) = 0.008) starts. Distances travelled by national level swimmers to the point of head emersion ranged from 5.94 m to 7.55 m, with differences observed due to gender (gender effect: F\({}_{1}\) = 14.59, \(p\) < 0.001, \(\eta^{2}\) = 0.11) and stroke (stroke effect: F\({}_{2}\) = 13.91, \(p\) < 0.001, \(\eta^{2}\) = 0.19). The start distance of the backstroke starts was longer than in butterfly and front-crawl (\(p\) = 0.001), whereas male swimmers presented an average of 0.70 m longer start than females. On the other hand, average velocities ranged from 1.5 to 2 m/s with differences between gender (gender effect: F\({}_{1}\) = 49.47, \(p\) < 0.001, \(\eta^{2}\) = 0.30) and stroke (stroke effect: F\({}_{2}\) = 3.12, \(p\) = 0.05, \(\eta^{2}\) = 0.05). The contribution of each start sub-phase to the emergent distance depended on the stroke (stroke \(\times\) phase effect: F\({}_{5,66}\) = 37.24, \(p\) = 0.001, \(\eta^{2}\) = 0.39), but not on the gender (gender*phase effect: F\({}_{2.83}\) = 2,25, \(p\) =0.09, \(\eta^{2}\) = 0.02), with backstroke glide and butterfly transition being shorter than the remaining strokes (\(p\) < 0.05) and with the leg kicking phase representing a different distance in each stroke (\(p\) < 0.05). For the average velocities in each start phase, backstroke leg kicking phase was slower (\(p\) < 0.05) than the remaining strokes, but no stroke differences were observed in the glide and transition phases. Statistical differences in each of the pairwise comparison for gender and stroke are shown in Table 1.  
The results of the correlation analysis of the push start sub-phases with times to 10 m are shown in Figure 1. No correlations were observed between the glide and transition parameters with time to 10 m, except the glide velocity on backstroke. On the other hand, the leg kicking velocities on butterfly and backstroke as well as the surface swimming velocities on front-crawl and backstroke were related to shorter 10 m times. For the distance measurements, no statistical correlations were observed with times to 10 m in any stroke or push start sub-phase, except the surface swimming distance in backstroke and butterfly. The linear multiple regression model for the freestyle stroke (Table 2) could not predict the time to 10 m beyond 20% with no significant relation between the distance or velocity variables in the different phases. For the backstroke, the linear multiple regression model (Table 2) significantly predicted the time to 10 m by 58.6%. The most significant variable here was the velocity of the leg kicking phase, where an increased velocity in the leg kicking resulted in a reduced time to 10 m. Here, it is also important to consider the transition phase, where an increase in the distance or velocity resulted in a greater time to 10 m. Finally, in the case of the butterfly stroke, the velocity equation showed a significant relationship in predicting the time to 10 m by 50%. In this case, the significant negative regression coefficient was obtained in the leg kicking phase, indicating that faster velocities in these phases resulted in lower times to 10 m.