Relationship between Asymmetry Profiles and Jump Performance in Youth Female Handball Players.

The relationships between asymmetries and performance or the identification of the asymmetry profile that has been routinely studied during jumping tests are largely derived from male-only and small sample size studies. Therefore, the aims of this study were: 1) to evaluate the magnitude and the direction of jump asymmetries (vertical and lateral) in three different age groups of adolescent female handball players, and 2) to identify the effect of asymmetry between limbs on jump performance in the three age groups. One hundred and eighty-five adolescent female handball players (age: 14.88 ± 1.49 years) were distributed in three groups: U14, U16 and U18 and performed two tests to assess jumping ability which were the single leg countermovement jump (SL-CMJ) and the single leg hop lateral (SL-HL). The magnitude of asymmetry in the SL-CMJ test (10.80%) was higher compared to that of the SL-LH test (6.47%), and there were no significant differences between particular categories. The direction of asymmetry represented by the Kappa values showed "poor" and "fair" levels of agreement in U14 and U16 categories, which means that asymmetries rarely favored the same side during each jumping test, but in contrast, in the U18 category the Kappa value result was "slight". There were significant correlations between SL-CMJ jumping asymmetries and jumping performance in the U18 category (r = 0.31 to 0.49). These data indicate that in order to identify the player's asymmetry profile, we need to consider the magnitude and the direction of different tests which will help better understand the natural deficits, contextualize them and consider appropriate training interventions for the reduction of inter-limb asymmetries.

Neuromuscular and Biomechanical Jumping and Landing Deficits in Young Female Handball Players.

Neuromuscular and biomechanical imbalances that exist in jumping and landing actions should be examined in order to intervene to decrease the risk of ACL injury. The main aim of this study was to analyse and compare, by chronological age, jumping and landing deficits in young female handball players using the Tuck Jump Assessment (TJA). A secondary aim was to relate the qualitative asymmetry values detected using the TJA to the quantitative asymmetry values detected starting from the single leg countermovement jump (SL-CMJ). Sixty-one young female handball players (age: 14.3 ± 1.5 years) were distributed into three groups: U12, U14 and U16 and performed the TJA test and the single leg countermovement jump (SL-CMJ). The female U12 category players obtained the highest scores in the TJA and there were significant differences between the U12 (12.11 ± 1.97) and U14 (10.89 ± 1.74) categories (p = 0.017; ES = 0.374). In the U12 category, the female players presented larger interlimb asymmetry magnitudes in the SL-CMJ test; they also obtained higher scores in the qualitative criteria of the TJA test that referred to asymmetry (r = 0.43; p = 0.027). The analysis of the jumping and landing pattern using TJA allowed us to identify that the lower extremity valgus at landing, foot contact timing not equal and landing contact noise are the main biomechanical deficits in young female handball players. Furthermore, the asymmetry values assessed qualitatively (TJA) are associated with the asymmetry values assessed quantitatively (difference in jump achieved with each limb in the SL-CMJ test) in younger categories.