The effect of forced even pacing and an opponent on end-spurt behaviour in freestyle pool swimming.

To investigate the effect of forced even pacing through virtual pacing assistance and an opponent in a competitive setting on end-spurt behaviour in freestyle swimmers, including related physiological underpinnings. Twenty-seven competitive swimmers and triathletes were recruited. There were four 1500 m freestyle trials: (i) familiarisation time trial, (ii) self-paced time trial (STT), (iii) head-to-head competition time trial (CTT) and (iv) forced even pacing through virtual pacing assistance time trial (FET). Eventually, 12 swimmers met the criteria for the CTT and FET to be included in the analysis. Changes in end-spurt behaviour, finishing time and physiological parameters (lactate, cortisol, noradrenaline and heart rate) were analysed using a linear mixed model with fixed effects for trials and a random effect for swimmer identity. A separate linear model was computed for competition outcome. The end-spurt for each race was determined by means of an end-spurt indicator (ESI; ESI > 0 greater end-spurt). Swimmers demonstrated a significantly greater ESI in FET (+2.6; p < 0.001) and CTT (+1.4; p = 0.022) compared to STT. Blood lactate concentration in FET (+1.0 mmol L-1; p < 0.001) and CTT (+1.6 mmol L-1; p < 0.001) was significantly higher than in STT. Winners had a significantly greater ESI than losers in CTT (+1.6 and p = 0.005). Swimmers utilised a greater end-spurt through metabolically optimal forced even pacing by virtual pacing assistance and in a head-to-head competition due a larger mobilisation of anaerobic reserves as indicated by greater blood lactate concentrations. Winners had a significantly greater end-spurt than losers despite similar metabolic disturbances.

The association of end-spurt behaviour with seasonal best time in long-distance freestyle pool swimming.

To analyse the association of seasonal best time, distance and different performance levels with end-spurt behaviour in one swimming season. Race results in 800 and 1500 m pool freestyle swimming in the season 2018/2019 including 14,930 races and 2650 swimmers were obtained. The end-spurt for each race was determined by means of an End-Spurt Indicator (ESI). Subsequently, ESI was used as a dependent variable and influences were analysed using a linear mixed model with fixed effects for seasonal best time, distance, and performance level amongst others. In the 800 and 1500 m races swimmers showed a mean ESI of 2.08 (95% CI: 2.02-2.13) and 3.68 (95% CI: 3.59-3.76), respectively. There was a significant association between seasonal best time and ESI, with a better seasonal best time showing a greater ESI (F = 70.5, P < .001, f2 = 0.04). A significant effect on greater ESI was also observed for longer distance (F = 1067.5, P < .001, f2 = 0.06) and higher performance level (F = 91.1, P < .001, f2 = 0.02). Elite swimmers had a mean ESI of 5.47 (95% CI: 4.91-6.03), sub-elite swimmers of 3.74 (95% CI: 3.53-3.95) and competitive swimmers of 2.41 (95% CI: 2.37-2.46). A more pronounced end-spurt is associated with seasonal best time in long-distance pool swimming, higher performance level of the swimmer and longer race distance.

Analysis of end-spurt behaviour in elite 800-m and 1500-m freestyle swimming.

To analyse the influence of distance, time point of competition, round and finishing position on end-spurt behaviour in swimming. Race results in 800-m and 1500-m freestyle swimming from the last 8 World Championships and 5 Olympic Games (1998-2016) including 1433 races and 528 swimmers were obtained. The end-spurt for each race was determined by means of an End-Spurt Indicator (ESI). The ESI was calculated by dividing the difference between the swim velocity of the last lap (SVLL) and the mean swim velocity of the middle part of the race (SVMP) by the respective individual standard deviation of SVMP. Subsequently, ESI was used as a dependent variable and influences were analysed using a linear mixed model with fixed effects for distance, time point of competition, round and finishing position. An end-spurt was evident in most swims for both race distances. The mean change in swim velocity between the middle part of the race and the last lap was 0.06 ± 0.02 m/s (1.2 ± 0.2 s) in the 800-m and 0.07 ± 0.02 m/s (1.5 ± 0.2 s) in the 1500-m. The finishing position within a race significantly affected the ESI (P < .001, t = 7.28). Specifically, when analysing finals only, ESI was significantly greater in medallists (5.76; quantile: 3.61 and 8.06) compared to non-medallists (4.06; quantile: 1.83 and 6.82; P = .001). The between-subject standard deviation was 1.66 (Cl: 1.42-1.97) with a relative variance component of 23%, while 77% of ESI variance remained unexplained. This is the first study using a newly developed indicator of end-spurt behaviour demonstrating that particularly medallists have a more pronounced end-spurt compared to non-medallists.