A training program to improve neuromuscular indices in female high school volleyball players.
Noyes FR, Barber-Westin SD, Smith ST, Campbell T. J Strength Cond Res. 2011 Aug;25(8):2151-60.
Several ACL prevention programs have been developed with the intent to decrease serious knee ligament injuries; particularly among female athletes. These programs are reported to improve overall lower limb alignment on a drop jump, increase knee flexor strength, increase knee flexion angle with landing, reduced knee moments and ground reaction forces, as well as reduced incidence of noncontact knee ligament injuries. One convenient way of encouraging teams to complete these programs is to incorporate them with other sport-specific performance training programs. Competitive volleyball is a sport that relies heavily on jumping and landing. Agel et al. reviewed 16 years of NCAA injury data and found that LE injury accounted for >55%of all injuries. In this article, Noyes et al evaluated if a sports-specific training program, that incorporated aspects of a previously documented knee ligament injury prevention program (Sportmetrics), could improve neuromuscular indices in female high school volleyball players. Thirty-four high school athletes from one high school participated in a 6 week program (3 days per week, 90-120 minutes per session). All athletes had no history of knee injury or symptoms at the time of the study. Of the 34 athletes 20 participants had previously undergone Sportsmetrics training within the past 12 months. All subjects underwent a video drop jump test, a multistage fitness test, a vertical jump test, and an abdominal strength test before and after the neuromuscular training program was initiated. With the pretest, no specific instruction was given on how to land or jump. Prior to training, the 20 athletes that previously participated in Sportsmetrics had significantly greater knee separation during landing (better knee alignment at landing) than the athletes that did not previously participate in the program. After, training however there was no difference between the groups. Seven of the 14 subjects that had not participated previously in the Sportsmetrics program demonstrated improved knee separation distance on landing after training. Other results indicated an improvement physical function performance with increases in VO2 max scores, vertical jump test, and sit up test.
Noyes et al. provide an interesting look at sports specific training with this study by focusing on demands related to volleyball. This may be an innovative way of incorporating injury prevention programs with other sport specific training programs. Overall, 74% of the subjects improved on all tests, and 14.7% improved on 3 of the 4 tests. That makes for almost 89% of the athletes improved in most of the tests administered. One obvious limitation to this study was a significant percentage of the athletes had prior training with the injury prevention program. But looking at the knee separation distance during the drop jump test among this, one can deduce good carry over of landing mechanics after training concluded. This raises the interesting question of how long do the neuromuscular benefits of these programs last? Another possible limitation is the time of training (90-120 minutes). This represents an extensive time commitment by the athletes and potentially a high financial cost for the team but fortunately, the program only used equipment that was in the high school. While there are some limits to this particular study, I think one can realize the importance of sports-specific training with athletics, and in particular the need to be as specific as possible to the demands of the sport involved. This may be an interesting way of integrating sport specific training and injury prevention. What are other clinicians’ experiences with ACL prevention/sports specific training relative to this topic?
Written by: Thomas Martin
Reviewed by: Jeffrey Driban