Table 1. Descriptive statistics (mean ± one standard deviation) and comparison between seniors and juniors in the 50 m freestyle event.
50 m freestyle
Mean±1SD
(Senior)		 Mean±1SD
(Junior)		 Mean difference
(95%CI)		 t (df) p d
[descriptor]		 Worthwhile change
[% of elite swimmers]
50 m race [s] 22.67±0.92 23.68±0.78 1.016 (0.765 to 1.268) 7.962 (1,179) <0.001 1.18 [large] 0.18 [0.81%]
S0-15 m
Speed [m·s-1] 2.66±0.13 2.54±0.11 -0.125 (-0.161 to -0.089) -6.920 (1,178) <0.001 1.00 [large] 0.03 [0.98%]
S15-25 m
Speed [m·s-1] 2.11±0.08 1.99±0.07 -0.116 (-0.139 to -0.094) -10.138 (1,179) <0.001 1.60 [large] 0.02 [0.76%]
SF [Hz] 1.03±0.05 1.01±0.07 -0.020 (-0.038 to -0.002) -2.182 (1,150) 0.028 0.33 [moderate] 0.01 [0.97%]
SL [m] 2.04±0.12 1.98±0.15 -0.069 (-0.108 to -0.023) -3.415 (1,158) 0.001 0.44 [moderate] 0.02 [1.18%]
SI [m2·s-1] 4.32±0.36 3.95±0.39 -0.374 (-0.484 to -0.264) -6.705 (1,179) <0.001 0.99 [large] 0.07 [1.67%]
S25-35 m
Speed [m·s-1] 2.07±0.08 1.95±0.06 -0.117 (-0.138 to -0.096) -10.882 (1,179) <0.001 1.70 [large] 0.02 [0.77%]
SF [Hz] 1.01±0.05 0.98±0.07 -0.026 (-0.044 to -0.009) -2.893 (1,157) 0.004 0.49 [moderate] 0.01 [0.99%]
SL [m] 2.05±0.11 1.99±0.15 -0.060 (-0.099 to -0.020) -2.944 (1,154) 0.003 0.46 [moderate] 0.02 [1.07%]
SI [m2·s-1] 4.24±0.34 3.88±0.37 -0.359 (-0.463 to -0.254) -6.786 (1,179) <0.001 1.01 [large] 0.07 [1.60%]
S35-45 m
Speed [m·s-1] 2.01±0.09 1.93±0.06 -0.080 (-0.103 to -0.058) -7.064 (1,179) <0.001 1.05 [large] 0.02 [0.90%]
SF [Hz] 0.98±0.06 0.95±0.06 -0.023 (-0.042 to -0.004) -2.392 (1,179) 0.018 0.50 [large] 0.01 [1.22%]
SL [m] 2.07±0.18 2.03±0.16 -0.035 (-0.085 to 0.015) -1.400 (1,179) 0.163 0.23 [moderate] 0.04 [1.74%]
SI [m2·s-1] 4.17±0.46 3.93±0.39 -0.240 (-0.364 to -0.115) -3.790 (1,179) <0.001 0.56 [large] 0.04 [0.86%]
S45-50 m
Speed [m·s-1] 1.83±0.08 1.86±0.07 0.038 (0.015 to 0.060) 3.326 (1,179) 0.001 0.40 [moderate] 0.01 [0.75%]
SF [Hz] 0.95±0.07 0.93±0.05 -0.020 (-0.039 to -0.002) -2.234 (1,179) 0.027 0.33 [moderate] 0.02 [1.47%]
SL [m] 1.93±0.15 2.00±0.15 0.081 (0.038 to 0.125) 3.712 (1,179) <0.001 0.47 [moderate] 0.03 [1.50%]
SI [m2·s-1] 3.52±0.36 3.74±0.38 0.225 (0.116 to 0.333) 4.082 (1,179) <0.001 0.59 [large] 0.08 [2.03%]
S – race section; SF – stroke frequency; SL – stroke length; SI – stroke index. t – t-test comparison; df – degree of freedom; p – significance level; d – Cohen’s d (effect size)