Table 4. Between-day reliability for PF and RFD across age categories.
| Category |
Variable |
Mean ±
SD |
ICC (95%
CI) |
ICC Interpretation |
CV (%)
(95% CI) |
SEM (95%
CI) |
| All |
PF |
1898.93
± 748.81 |
0.95 (0.92-0.97) |
Excellent |
7.6 (6.6-8.6) |
39.01 (35.11-42.91) |
| RFD50 |
3349.71
± 2411.45 |
0.48 (0.32-0.64) |
Poor |
39.3 (33.4-45.2) |
1282.64
(1154.37-1410.90) |
| RFD100 |
3555.87
± 2271.47 |
0.73 (0.62-0.83) |
Moderate |
27.8 (23.6-32.0) |
614.53
(553.08-675.99) |
| RFD150 |
3513.91
± 2025.33 |
0.79 (0.71-0.87) |
Good |
22.9 (19.5-26.4) |
416.52
(374.87-458.17) |
| RFD200 |
3501.99
± 1786.05 |
0.81 (0.75-0.89) |
Good |
19.6 (16.3-22.8) |
338.10
(304.29-371.92) |
| RFD250 |
3289.96
± 1531.18 |
0.87 (0.82-0.93) |
Good |
14.7 (12.4-17.1) |
205.23
(184.71-225.75) |
| U12 |
PF |
1036.19
± 184.02 |
0.77 (0.61-0.93) |
Good |
7.5 (5.4-9.6) |
41.24 (37.11-45.36) |
| RFD50 |
1812.85
± 792.50 |
0.35 (0.04-0.71) |
Poor |
33.6 (21.3-45.8) |
520.12
(468.10-572.13) |
| RFD100 |
1822.43
± 738.51 |
0.35 (0.02-0.69) |
Poor |
26.3 (16.2-36.3) |
450.89
(405.80-495.98) |
| RFD150 |
1823.32
± 708.99 |
0.46 (0.12-0.76) |
Poor |
23.9 (16.9-30.9) |
362.69
(326.42-398.96) |
| RFD200 |
1875.15
± 608.47 |
0.59 (0.31-0.85) |
Moderate |
19.3 (14.4-24.3) |
246.15
(221.53-270.76) |
| RFD250 |
1747.53
± 521.38 |
0.58 (0.35-0.86) |
Moderate |
16.6 (12.7-20.4) |
205.75
(185.17-226.32) |
| U15 |
PF |
1946.07
± 494.25 |
0.85 (0.78-0.94) |
Good |
8.2 (6.6-9.8) |
71.88 (64.70-79.07) |
| RFD50 |
3469.93
± 2297.85 |
0.08 (0.00-0.38) |
Poor |
49.2 (40.0-58.4) |
2182.95
(1964.66-2401.25) |
| RFD100 |
3543.24
± 1647.33 |
0.33 (0.10-0.61) |
Poor |
32.7 (26.5-38.8) |
1131.70
(1018.53-1244.87) |
| RFD150 |
3424.35
± 1427.75 |
0.47 (0.28-0.74) |
Poor |
25.6 (19.9-31.3) |
760.71
(684.64-836.78) |
| RFD200 |
3417.90
± 1284.60 |
0.45 (0.30-0.75) |
Poor |
23.7 (18.0-29.4) |
703.89
(633.50-774.28) |
| RFD250 |
3263.41
± 1028.98 |
0.60 (0.47-0.83) |
Moderate |
16.1 (12.0-20.3) |
405.29
(364.76-445.82) |
| U18 |
PF |
2738.00
± 435.94 |
0.79 (0.55-0.91) |
Good |
6.7 (4.9-8.5) |
91.86 (82.67-101.05) |
| RFD50 |
4778.79
± 2816.51 |
0.70 (0.43-0.88) |
Moderate |
28.4 (21.5-35.4) |
822.23
(740.00-904.45) |
| RFD100 |
5435.97
± 2813.88 |
0.79 (0.56-0.92) |
Good |
21.3 (14.7-28.0) |
571.56
(514.40-628.71) |
| RFD150 |
5487.32
± 2190.50 |
0.79 (0.56-0.91) |
Good |
17.7 (11.8-23.7) |
458.38
(412.55-504.22) |
| RFD200 |
5397.21
± 1609.62 |
0.79 (0.55-0.91) |
Good |
13.0 (8.7-17.2) |
338.72
(304.84-372.59) |
| RFD250 |
4990.62
± 1208.25 |
0.75 (0.50-0.90) |
Good |
10.7 (7.3-14.1) |
293.14
(263.82-322.45) |
PF = peak force; RFD = rate of force development; SD = standard deviation; ICC = intraclass correlation coefficient; CI = confidence interval; CV = coefficient of variation; SEM = standard error of measurement.
