Home > Injury Prevention, Knee Injury, Movement Dysfunction > Changes in Movement Control are Influenced by Duration of Training – Implications for Rehabilitation and Injury Prevention

Changes in Movement Control are Influenced by Duration of Training – Implications for Rehabilitation and Injury Prevention


Padua DA, DiSefano LJ, Marshall SW, Beutler AI, de la Motte SJ, DiStefano MJ.  Retention of Movement Pattern Changes After a Lower Extremity Injury Prevention Program Is Affected by Program Duration.  American Journal of Sports Medicine 40(2):300-306, 2012

What issue was addressed in the study, and why?

Prevention of ACL and other knee injuries is an important issue for sports medicine professionals given the high cost and long term disability associated with these injuries.  Recent randomized controlled trial studies have shown that 15-minute injury prevention exercise program scan reduce the rate of ACL and knee injuries during sport.  However, injury rates return to their original levels once individuals cease performing the injury prevention exercise program.

The primary goals of injury prevention exercise programs are to improve neuromuscular control and overall movement quality.  Findings of elevated injury rates once stopping an injury prevention program suggest that changes in neuromuscular control and movement quality are not permanent; however, research has not investigated this topic.  Therefore, the purpose of this study was to determine if changes in movement quality/control are maintained once individuals had stopped performing an injury prevention program for 3 months.  This study also investigated the influence of program duration (3-month training program vs. 9-month training program) on people’s ability to maintain improvements in movement quality/control.

Who were the participants in the study?

A total of 140 youth soccer athletes participated in this study.  Individuals who improved their movement quality/control over the course of the injury prevention program were included in the final analysis (84 total subjects).  Individuals were further subdivided into 2 groups based on the duration of their injury prevention program (3-month training period (short duration) = 33 subjects; 9-month training period (extended duration) = 51 subjects).

What did the researchers do for this study?

All participants performed an integrated exercise program that incorporated flexibility, balance, strength, and plyometric/agility exercises.  The exercise program was performed as a dynamic warm up in replace of the normal warm up routine.  The exercise program took 10-15 minutes to perform and was completed 3-4 times per week during the intervention period.  The Short-Duration group performed the exercises for 3-months.  The Extended-Duration group performed the exercises for 9-months.  Trained research assistants taught the athletes the exercise program and visited the athletes once a week to monitor compliance and correct exercise technique.  Participants were instructed to think about their movement and rely on specific cues when performing the exercises (keep toes pointing forward, keep knees over toes, land as soft as possible).

Prior to beginning the exercise program (Pre Test) the participants performed a jump-landing task (3-trials) that was recorded with a video camera.  The Landing Error Scoring System (LESS) was then used to grade the individual’s overall movement quality.  Participants repeated the jump-landing task after immediately completing the exercise program (Post Test) and again after 3-months of performing the exercise program (Retention Test).  The researchers then compared the Short-Duration and Extended-Duration groups LESS scores across the three time periods (Pre Test, Post Test, Retention Test).

What new information was learned from this study?

Both the Short Duration and Extended Duration groups improved their LESS scores from Pre Test to Post Test.  There was no difference in the amount of improvement in LESS scores between groups.  However, at the Retention Test the Short Duration group’s LESS scores returned to Pre Test levels and were worse than at Post Test.  This was not the case for the Extended Duration group as their Retention Test LESS scores remained the same as at Post Test and were still improved compared to Pre Test.  Thus, the Extended Duration group retained their improvements in movement quality / control while the Short Duration group did not.

This study demonstrates that the duration of training has a significant impact on the ability to maintain improvements (retention) in movement quality/control following an injury prevention program.  Extended Duration exercise programs appear to be an important component of successfully achieving retention of improvements in movement quality/control once ceasing to perform the program.

What are the clinical applications of this study?

Several important clinical applications come from this study.  First, we should not assume that improvements in movement quality/control are permanent once an individual has made initial changes in their movement patterns.  Individuals in the Short Duration group were able to improve their movement quality/control after 3 months of training, but after stopping the program they returned to their baseline levels.  This especially important when considering rehabilitation and corrective exercise programs as it is common to achieve changes in movement quality / control in less then 3 months and then the patient / client stops performing the program.  These findings suggest that individuals will only return to their original movement patterns if continued assessment and maintenance of the exercise program is maintained.

Second, longer duration exercise programs that are continued once individuals have initially improved their movement patterns may be required to elicit more permanent changes in one’s movement patterns.  Individuals in the Extended Duration group likely achieved improvements in movement quality/control after 3-months as did the Short Duration group.  However, the Extended Duration group continued to perform these exercises for an additional 6-months after achieving this improvement.  The additional performance of the exercises after making initial improvements may have allowed for these individuals to master the exercises and elicit more permanent improvements in their movement patterns.  These findings have direct implications to rehabilitation and corrective exercise programs.

These findings suggest that injury prevention training should be a continual process where athletes are repeatedly monitored and perform their exercise program even after making initial improvements.  By replacing the traditional warm up with these types of injury prevention programs we can achieve the same effects as traditional warm ups, but have the added benefit of improving movement quality.

What are the limitations of the study, and what areas should be considered for future research?

Several limitations should be considered.  First, the LESS is a clinical assessment of movement quality/control and is not the same as 3-D motion analysis; however, the LESS has been shown to have good validity and reliability relative to 3-D motion analysis.  Future research may consider using 3-D motion analysis to study retention following an injury prevention program.  Another possible limitation was the age group of study participants (11-17 years).  It is not clear if the duration of training has similar effects in younger or older populations.  Future research may consider investigating different age groups and also different retention time periods.

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