A little while back I posted a review of a study looking at the interrater reliability of the Functional Movement Screen.  Today I’ll be looking at another study on the FMS to further elucidate the research that has been done on this popular system.

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Again, I’m not trying to rip anyone apart here.  I’m primarily looking the the research for my own benefit and in doing so have decided to share it with you.  If you care to read this study for yourself you can get the full text for free at the top right hand of the page HERE.

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Core strength: A New Model for Injury Prediction and Prevention

Peate WF, et al.   Journal of Occupational Medicine and Toxicology 2007, 2:3.

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Background

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Injuries to firefighters are among the highest of all occupations.  Research suggests that decreased core strength may contribute to injuries of the back and extremities, that training may decrease musculoskeletal damage, and that core stability can be tested using functional movement methods.  The purpose of this study was to use the Functional Movement Screen to better assess the risk of firefighter injury due to functional movement performance, and to decrease injuries by using that information.

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Methods Part 1: Screening

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Functional Movement Screen conducted on 433 active firefighters.  Analyzed correlation between FMS scores and data from fire department database including injury history, age, gender, tenure, and rank.

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Methods Part 2: Intervention

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Firefighters underwent 3 hour seminars (actual number attended by each firefighter hard to determine based on the way the study was written) covering causation and prevention of injuries.  During seminars each firefighter demonstrated proper body mechanics in sample work settings and taught how to minimize spinal load during work situations.

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“For example, firefighters were instructed to use an outstretched arm held against a firm surface as a prop to decrease mechanical load on the back when the firefighter’s spine is in lumbar flexion.”

 

Subjects were taught how to activate their transversus abdominis as well.

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“Participants were shown that muscle’s location in the anterior abdominal wall. Photos of various methods of recruiting and strengthening the TA with written explanations were provided, along with verbal reinforcement of the material.  Once the firefighter demonstrated competency in basic TA muscle tightening, physiotherapy balls and dowels were employed to challenge the firefighter in different positions that mimicked firefighting tasks.”

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Core exercises included three basic models which are similar to hamstring pushups, hamstring pushups with the upper back on a ball (hip thrusts?), and hamstring pushups with the feet on a ball.  Arm movement was added using weights of various amounts.  A detailed explanation of exercise variations, progressions, and how loading was used is lacking in this paper.  There are a few photos, but you’d be hard pressed to repeat this protocol by just reading the article.

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Injuries after one year were compared to injuries in the year previous to the addition of the intervention.

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Results Part 1: Screening

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Increasing age, rank, and tenure was associated with a lower functional movement score using linear regression.  After adjusting for age and using multiple regression, those with a previous injury tended to score an average of 0.24 points lower on the FMS, but this relationship was not significant (p = 0.25).  When the scoring on the FMS was observed as a pass or fail score (for some reason they said a fail was below 16) the odds of failing the FMS after having a previous injury was 1.68 times greater based on multiple logical regression (p= 0.033).
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Results Part 2: Intervention

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Compared to the previous year, lost time due to injuries was reduced by 62%!  The total number of injuries was reduced by 44%.  Injuries to the back and upper extremities were reduced, but injuries to the lower extremities were not reduced by the intervention.
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Funding
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Administration of the Tucson Fire Department
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My Thoughts

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I’ve noticed that this article is frequently used to support the Functional Movement Screen as a tool for screening for injury risk prior to physical activity.  However, when you look at the outcomes, the FMS was only able to determine that the risk of injury increases with age, tenure, and rank (the latter two are also typically related to age).  I don’t think I’m going out on a limb to suggest that most people could have told you this before even running the FMS.

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Although the authors do mention that there was a relationship between FMS score and previous injury based on linear regression, this relationship totally disappeared when corrected for age which appears to the major determinant of injury in this study.  The authors make a point of mentioning that they were indeed related but shy of statistical significance using multiple regression.  However, the p value (a measure of statistical probability) was 0.25 which is a LONG way from statistical significance at 0.05.  I would think it is fair to say that there is pretty much no relationship between FMS and previous injury in this study once you control for age.  Changing the FMS to a pass or fail criterion did make it better for determining risk after an injury.  As was mentioned earlier though, you don’t really need to do this if you just look at age as the primary predictor.
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I have also seen this study referenced to support the idea that the interventions based on the FMS are effective for injury prevention.  Taking a look at the study though, there are a few errors with this assumption.
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- The FMS was conducted at the beginning of the study and there was no follow up testing at the end to determine if there was an improvement in FMS score related to the 62% reduction in lost time due to injury.

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- The intervention had nothing at all to do with the FMS.  Everyone virtually received the same intervention regardless of score on the testing.  I’m no expert, but I’m pretty sure this isn’t how the FMS is supposed to be used.

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- There were other factors within the intervention besides the physical training.  Subjects were taught about injury mechanisms, bracing, and how to move in the work environment.  Personally I agree that this is a great way to intervene to make a larger difference in the safety of the firefighters.  However, from a scientific perspective, it introduces a whole bunch of other variables that could have lead to decreases in injuries that had nothing to do with the FMS.

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- There was no control group.  Injuries were compared to previous years which makes sense from a operations perspective, but when doing a scientific experiment a group not recieving treatment is usually run alongside the group that does.  In this case, it wasn’t done making comparisons in injury rates pretty difficult.  Again, a 62% decrease in lost time is excellent, but it could be due to factors beyond the intervention itself (i.e., less fires this year).
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Summing Up

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At the risk of pissing off a lot of people, I’m going to suggest that the FMS did not play an integral role (actually any role at all) in the improvements seen in this study.  Moreover, age was seen to be the biggest predictor of future injury which could technically be used alone instead of having to run the FMS on such a large group each year.

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As far as the Functional Movement Screen is concerned, the intervention doesn’t really matter because they weren’t really linked in any way.  That said, if you’re a firefighter, you might want to find out what these people are doing because it just may prevent you from experiencing an injury.  If you’re a firefighter and you’re a little older, you might want to consider a good accident benefits plan.

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What do you think?