Table 4 Multi-level regression analyses for change in swimming speed for 400 m, 800 m, and 1,500 m in swimmers at international level across years for women and men (Model 1) with correction for multiple participations (Model 2) and age of athletes with multiple participations (Model 3)

400 m women long course

1

0.005

0.001

0.701

6.663

< 0.001

2

0.005

0.001

0.701

6.663

< 0.001

3

0.005

0.001

0.711

6.678

< 0.001

400 m women short course

1

0.004

0.001

0.604

5.134

< 0.001

2

0.004

0.001

0.604

5.134

< 0.001

3

0.004

0.001

0.620

5.052

< 0.001

400 m men long course

1

0.003

0.001

0.395

2.913

0.006

2

0.003

0.001

0.395

2.913

0.006

3

0.003

0.001

0.418

3.107

0.003

400 m men short course

1

0.004

0.001

0.566

4.660

< 0.001

2

0.004

0.001

0.566

4.660

< 0.001

3

0.004

0.001

0.566

4.629

< 0.001

800 m women long course

1

0.004

0.001

0.540

4.395

< 0.001

2

0.004

0.001

0.540

4.395

< 0.001

3

0.004

0.001

0.547

4.299

< 0.001

800 m women short course

1

0.004

0.001

0.635

5.580

< 0.001

2

0.004

0.001

0.635

5.580

< 0.001

3

0.004

0.001

0.599

5.127

< 0.001

800 m men long course

1

0.004

0.001

0.448

3.398

0.001

2

0.004

0.001

0.448

3.398

0.001

3

0.003

0.001

0.423

2.973

0.005

800 m men short course

1

0.004

0.001

0.590

4.960

< 0.001

2

0.004

0.001

0.590

4.960

< 0.001

3

0.004

0.001

0.584

4.893

< 0.001

1,500 m women long course

1

0.003

0.001

0.482

3.730

0.001

2

0.003

0.001

0.482

3.730

0.001

3

0.003

0.001

0.448

3.224

0.002

1,500 m men long course

1

0.002

0.001

0.326

2.342

0.024

2

0.002

0.001

0.326

2.342

0.024

3

0.002

0.001

0.344

2.403

0.020

1,500 m men short course

1

0.003

0.001

0.498

3.895

< 0.001

2

0.003

0.001

0.498

3.895

< 0.001

3

0.003

0.001

0.492

3.822

< 0.001