Plyometric Training
From the Cincinnati Sportsmedicine Research and Education Foundation and Deaconess Hospital, Cincinnati, Ohio.

Objective
The purpose of this study was to test the effect of a jump-training program on landing mechanics and lower extremity strength in female athletes involved in jumping sports. These parameters were compared before and after training with those of male athletes. The program was designed to decrease landing forces by teaching neuromuscular control of the lower limb during landing and to increase vertical jump height.

Results
After training, peak landing forces from a volleyball block jump decreased 22%, and knee adduction and abduction moments (medially and laterally directed torques) decreased approximately 50%. Multiple regression analysis revealed that these moments were significant predictors of peak landing forces. Female athletes demonstrated lower landing forces than male athletes and lower adduction and abduction moments after training. External knee extension moments (hamstring muscle-dominant) of male athletes were threefold higher than those of female athletes. Hamstring-to-quadriceps muscle peak torque ratios increased 26% on the nondominant side and 13% on the dominant side, correcting side-to-side imbalances. Hamstring muscle power increased 44% with training on the dominant side and 21% on the nondominant. Peak torque ratios of male athletes were significantly greater than those of untrained female athletes, but similar to those of trained females. Mean vertical jump height increased approximately 10%.

Conclusion
This training may have a significant effect on knee stabilization and prevention of serious knee injury among female athletes.

Training & Incidence of Injury
From the Cincinnati Sportsmedicine Research and Education Foundation and Deaconess Hospital, Cincinnati, Ohio.

Objective
To prospectively evaluate the effect of neuromuscular training on the incidence of knee injury in female athletes, we monitored two groups of female athletes, one trained before sports participation and the other not trained, and a group of untrained male athletes throughout the high school soccer, volleyball, and basketball seasons.

Results
There were 14 serious knee injuries in the 1263 athletes tracked through the study. Ten of 463 untrained female athletes sustained serious knee injuries (8 non-contact), 2 of 366 trained female athletes sustained serious knee injuries (0 non-contact), and 2 of 434 male athletes sustained serious knee injuries (1 non-contact). The knee injury incidence per 1000 athlete-exposures was 0.43 in untrained female athletes, 0.12 in trained female athletes, and 0.09 in male athletes (P = 0.02, chi-square analysis). Untrained female athletes had a 3.6 times higher incidence of knee injury than trained female athletes (P = 0.05) and 4.8 times higher than male athletes (P = 0.03). The incidence of knee injury in trained female athletes was not significantly different from that in untrained male athletes (P = 0.86). The difference in the incidence of non-contact injuries between the female groups was also significant (P = 0.01).

Conclusion
This prospective study demonstrated a decreased incidence of knee injury in female athletes after a specific plyometric training program.