Abstract
Longitudinal investigations into the development of inter-limb asymmetry in
sports are scarce. This study examined the development of change of direction
(COD) asymmetry magnitude in youth elite tennis players. Dominant (overall best
performance) and non-dominant (best performance on the other side) scores and
COD asymmetry magnitude were quantified annually (up to six years) in 323 male
and 235 female players (ages 6 to13 years). Linear mixed effects regression
models examined the development of COD performance and asymmetry magnitude
according to players’ chronological age and sex. Kappa coefficients
examined the consistency for the direction of asymmetry across test occasions.
Regardless of sex, COD performance significantly improved (p<0.001)
while COD asymmetry magnitude significantly decreased
(− 0.17±0.87% / year) with increasing
chronological age. Regardless of age, males showed significantly lower COD times
(− 0.111±0.091 s) and lower COD asymmetry
magnitude (− 0.30±1.00%) compared to females.
The slight and poor (k-value=0.02–0.00) kappa coefficients for
males and females, respectively, highlight the direction specificity of
functional asymmetry. These data show that whereas performance of the COD test
improved, the magnitude of COD asymmetry declined across chronological age in
youth tennis players.
Key words
interlimb - physical performance - youth athletes - unilateral - monitoring - racquet sports
