Table 1.
Search terms used to find eligible articles.
Fig 1.
14 studies were added after updated search.
Table 2.
Inclusion criteria for articles eligible for the review.
Table 3.
The different variations of strength tests included in the analysis and the number of studies using each test.
Fig 2.
Variety in testing methodologies: Number of different tests for each physical characteristic and the number of studies each characteristic was measured.
CoD: change of direction.
Fig 3.
Yearly performance measured in all studies included for 10 m sprint, CMJ, intermittent endurance and handgrip strength.
Boys are the left figures, and girls the rigth. Blue lines represent longitudinal studies, and black dotted lines are the cross-sectional studies. CMJ: countermovement jump height.
Fig 4.
Weighted data for height (A), body mass (B) and percentage body fat (C). The sample size for each age group is indicated below the x-axis. The numbers in parentheses represent the available studies for the respective age group. Dotted lines highlight age groups with two or fewer studies.
Fig 5.
Weighted data for lower (A) and upper (B) body strength, CMJ (C), intermittent endurance (D), 10-m sprint (E), 30-m sprint (F), and CoD (G) results. The sample size for each age group is indicated below the x-axis The numbers in parentheses represent the available studies for the respective age group. Dotted lines highlight age groups with low samples. Norm: normalized. Wtd; weighted. LB: lower body. CoD: change of direction. Int: intermittent. Perf: performance.