Table 2 Comparison of percentiles based on cross-sectional vs. longitudinal analysis of female swimmers.

From: Comparing cross-sectional and longitudinal tracking to establish percentile data and assess performance progression in swimmers

 

Age categories

Early junior

10–14 years

Late junior

15–17 years

Sub-elite

18–20 years

Elite

 > 21 years

 

F-value

P-value

pη2

80–99th percentiles

Cross-sectional

02:38.57 ± 13.01

02:23.78 ± 11.50#

02:17.07 ± 10.66#

02:13.84 ± 10.69#

(a)

F(1|198) = 11

P < 0.001

0.06

Longitudinal

02:29.53 ± 11.70*

02:16.71 ± 10.04*#

02:12.95 ± 09.59#

02:13.28 ± 09.71

(b)

F(1|261) = 10,083

P < 0.001

0.98

(c)

F(1|261) = 394

P < 0.001

0.67

40–59th percentiles

Cross-sectional

03:01.96 ± 13.11

02:42.76 ± 12.54#

02:35.01 ± 11.70#

02:35.45 ± 11.50

(a)

F(1|198) = 28

P < 0.001

0.12

Longitudinal

02:48.28 ± 11.57*

02:32.53 ± 11.01*#

02:28.25 ± 10.47*#

02:31.62 ± 10.68#

(b)

F(1|222) = 7111

P < 0.001

0.97

(c)

F(1|222) = 281

P < 0.001

0.59

1st–20th percentiles

Cross-sectional

03:34.78 ± 17.78

03:11.49 ± 18.00#

03:05.15 ± 18.83#

03:11.06 ± 20.29#

(a)

F(1|198) = 27

P < 0.001

0.12

Longitudinal

03:15.87 ± 16.10*

02:58.15 ± 16.84*#

02:55.09 ± 17.45*#

03:01.78 ± 18.03 *#

(b)

F(2|305) = 2062

P < 0.001

0.91

(c)

F(2|305) = 80

P < 0.001

0.29

  1. Analysis of variance (ANOVA) with repeated measure and one between subject factor was used to compare upper (80–99th), medium (40–59th), and lower percentiles (01–20th) based on mean [mm:ss.00] ± standard deviation [ss.00] across the 200 m events of all swimming strokes.
  2. (a) Main effect: type of analysis (cross-sectional vs. longitudinal).
  3. (b) Main effect: age category (early junior–late junior–sub-elite–elite).
  4. (c) Interaction effect: type of analysis x age group.
  5. Post-hoc comparison.
  6. *Significant difference to cross-sectional analysis.
  7. #Significant difference to previous age category.
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