AGE APPROPRIATENESS OF COMMON NEUROMUSCULAR TRAINING EXERCISES
Authors: Janosky Joseph 
Published: March 2019

Background

Anterior cruciate ligament (ACL) injury is a significant public health concern in the US with at least 250,000 injuries occurring annually. The rate of ACL reconstruction in adolescents has risen 33% in the past 20 years. Much effort has been dedicated to developing neuromuscular training (NMT) programs to reduce the risk of ACL injury. While preventive programs have been successful in decreasing the rate of ACL injury in young populations, the appropriateness of NMT exercises across different age groups has not yet been demonstrated. The purpose of this study is to determine if children ages 8-11 and 12-15 can perform common NMT exercises with equal ability.

Methods

In 2016, Hospital for Special Surgery (HSS) developed a series of NMT programs for young athletes. Seven exercises were selected for evaluation from both the Beginner (8-11) and Intermediate (12-15) programs. Male and female subjects aged 8-15 were recruited from schools and youth sports organizations in and around New York City. Informed consent/assent was obtained from each subject. Participants completed a demographic survey and were assigned a subject ID before testing. Participants completed two trials of each exercise. Performance was assessed after receiving visual/verbal exercise instruction and again after receiving visual/verbal cues that reinforced correct exercise technique. Three sports medicine practitioners evaluated each exercise using three performance criteria. Exercise technique was deemed correct when at least two evaluators agreed that neutral alignment of the cervical spine, lumbopelvic complex and lower extremities was maintained during each exercise. Comparisons of performance within each sex were made for 8-9 & 10-11 and 12-13 & 14-15 groups using Chi-square test or Fisher’s exact test using SAS version 9.4 (SAS Inc., Cary, NC).

Results

301 total participants were evaluated (8-11 years: n = 165, 54.2% female; 12-15 years: n = 136, 39.9% female). The percentage of participants who performed exercises correctly are shown in Table 1 and 2 (attached). There was no significant difference between male and female participants who completed exercises correctly in either cohort. There was also no significant difference noted in exercise performance between participants aged 8-9 & 10-11 years or between participants aged 12-13 & 14-15 years. The use of technique cues significantly increased the percentage of participants who correctly completed the exercise across all ages and sexes (p < 0.001). 21% of the cohort aged 8-11 completed exercises correctly when provided with exercise instruction and 45% completed exercises correctly when provided with technique cues. 29% of the cohort aged 12-15 completed exercises correctly when provided with exercise instruction and 59% completed exercises correctly when provided with technique cues. The kappa statistic was used to measure inter-rater reliability and among all criteria for all evaluators k = 0.31 (8-11 cohort) and k = 0.42 (12-15 cohort).

Conclusion

Our results indicate that male and female children aged 8-9 & 10-11 years and 12-13 & 14-15 years can perform common NMT exercises with equal ability. This is an important consideration when designing preventive programs for young athletes based on chronological age. Additionally, only one-fourth all study participants were able to perform common NMT exercises with correct technique when provided with visual/verbal exercise instruction, while over one-half of the participants were able to perform these same exercises correctly when provided with visual/verbal technique cues. This improvement highlights the importance of providing cues that effectively improve exercise technique for young athletes. Based on motor learning theory, repeated cuing would likely increase the percentage of children who perform NMT exercises correctly. These results call attention to the urgent need for coaches and physical educators to provide appropriate technique cues when implementing NMT programs. [Table: see text][Table: see text]