This study examined whether an extrinsic motivator, such as an overhead goal, during a plyometric jump may alter movement biomechanics. To maximize plyometric training efficiency it has been suggested that feedback through the use of targets or force plate analysis be incorporated.
PURPOSE
The purpose was to examine the effects of an overhead goal on vertical jump height and lower extremity biomechanics during a drop vertical jump (DVJ) and compare the effects on female versus male athletes.
METHODS
2 collegiate soccer teams, 18 female (ht 165 ± 5 cm, wt 66 ± 10 kg, age 20.0 ± 1.2 yrs) and 17 male athletes (ht 177 ± 6 cm, wt 74 ± 7 kg, age 21.1 ± 1.6 yrs), participated in this study. DVJ was performed both with (OG) and without (NOG) the use of an overhead goal. Motion and force data was collected with 8 cameras (Motion Analysis Corporation, 240Hz) and 2 forceplates (AMTI, 1200Hz). A 2-way mixed design ANOVA was used to determine the main effects and interaction of overhead goal and gender(P < 0.05).
RESULTS
Vertical jump height was greater (P=0.002) with the overhead goal for both male (NOG 48.3±1.1cm, OG 49.4±1.2cm) and female athletes (NOG 36.8±1.1cm, OG 37.3±1.0). A main group effect for gender was found in vertical jump height (p<0.001) with males jumping 32% higher than females. In addition, males had 19% greater maximum takeoff vertical force (P=0.009).
Males had 18% greater maximum takeoff hip extensor moment than females regardless of whether the overhead goal was used or not (P=0.02). The knee moment was significantly greater with the overhead goal indicative of increased knee extensor recruitment. A main effect for the OG was found for the maximum takeoff knee extensor moment (P=0.04). Males and females performed the DVJ differently with the overhead goal.
A significant goal × gender interaction was found for stance time (P=0.02) and maximum ankle (P=0.04) and knee flexion angles (P=0.04). Stance times were significantly shorter in males (P=0.02) with the overhead goal, while females showed no difference in stance time between OG and NOG conditions (P=0.51). Knee angle in females was not different between goal conditions, but kinematic analysis did show a trend (P=0.09) toward increased knee range of motion with the overhead goal. In addition, maximum ankle angle in women showed a similar trend (P=0.08), with increased range of motion during the overhead goal condition. Maximum ankle (P=0.31) and knee (P=0.20) angles were not significantly different in males with and without the goal.
CONCLUSIONS
These results indicate that overhead goals may be incorporated during training and testing protocols to alter lower extremity biomechanics that can increase performance.
