Angle Specificity of the Knee Extensor Age-Related Profile in Young Female Athletes

Abstract

The angle specificity of the knee extensor age-related profile was examined in young females (13 - 19 yr). Twenty-one track & field jumpers, 20 volleyball players and 20 non-active females were separated into the youngest and the oldest age categories, based on the official competitive age categories. The maximum knee extensor isometric torque (T_MAX) was measured at 9 knee angles. The relationships between T_MAX at the peak of the torque-angle curve and at the other knee angles (angle-angle relationships) were expressed by R² (%). Statistics included two-way ANOVA for age category differences and curve fitting to R² joint angle trend lines. Differences between age categories were significant for the volleyball players and the non-active females (p < 0.05). Age category had an angle specific impact on angle-angle relationships in the athletes, with the youngest ones demonstrating greater R² decrease at the more extended, or more flexed, knee angles. Significant quadratic R² joint angle trend lines were found in all track & field jumpers (p < 0.05) and, in the youngest only volleyball players (p < 0.05), but not in the non-active females (p > 0.05). In conclusion, the knee extensor profiles of young female athletes show an age-related angle specificity that should be accounted for when treating athletes within the age range examined.

Key words

adolescent - isometric - correlations - injury - track and field jumpers - volleyball players

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