Previously, we discussed the pros and cons of the Functional Movement Screen (here). Some time has passed since that initial study and more work has been done. It is important to realize that the FMS is one of the few tools that coaches can easily learn to evaluate movement quality. Coaches on the whole have been left to their own devices and rarely receive the education in biomechanics that Kinesiologists or Physiotherapists do. That said, it is important to understand the limitation of the tool, when and where it can and can’t be used. When you only have a hammer, you might try to hammer your way out of a problem that really requires a screwdriver and you might exacerbate the problem despite good intentions.

Kiesel et al. (2007) wanted to determine if the FMS could predict which players on an American football team would be injured during the course of the season. Working with an unnamed pro-team, the tests were conducted pre-season. The tests are 1) the overhead squat, 2) hurdle step, 3) in-line lunge, 4) shoulder mobility, 5) active straight leg raise, 6) trunk stability push-ups and 7) rotary stability test. This is a relatively complete battery for generalized joint mobility, muscle flexibility, neuromuscular coordination, strength, muscular endurance and core activation.

All tests are scored 0 to 3 for various levels of mastery with 3 being excellent. Out of a possible score of 21, the team average was 16.9 (this indicates that even some professional athletes have some movement deficits that do not hinder them in their chosen sport). It was noted that those with a score above 17.4 were not injured throughout the season while those with a score below 14.3 generally were.

Statistical analysis demonstrated the test was highly specific (0.91) but not sensitive (0.54). Now, those scoring below 14.3 were found to have a 15% greater chance of injury but (and this is the important bit) the FMS could not determine if it was a muscular, neurological, neuromuscular coordination, ligament, tendon, fascial or other issue causing the problem that lead to the higher probability of injury.

This is a concern. Giving coaches a tool that while reliable enough to find a problem, cannot determine the source of the problem puts them in a position where they MUST send their athletes to doctors or therapists for assessment. As the vast majority of coaches are qualified to judge an overhead squat but not why someone’s hips are tight, it becomes incumbent upon the coach to develop a relationship with a therapist or doctor to help determine the reasons and develop appropriate treatments thereof. 

Given this incredibly high specificity, the question of inter-rater reliability arises. This is an important issue. If two testers, seeing the same data set cannot agree on how to score a client, it becomes a subjective tool rather than an objective assessment. These types of problems have long plagued performance coaching and rehabilitative therapy. Some tests have few objective criteria and it is up to the tester to judge.

Since the FMS is considered both popular and powerful, some basic level of inter-rater reliability should be found. Kate et al. (2010) had 2 novices trained in the FMS and 2 experts in the FMS system watch videos of 40 subjects performing the 7 tests. The novices agreed on 82.4% of the test scored while the experts agreed on 76.5% of the scores. This does suggest a moderate-strong inter-rater reliability. This way, a player assessed by the FMS one year in one part of the country with one coach, could take those results and be assessed for improvement by a different coach in a different part of the country and have a reasonable expectation that the second one will be accurate in comparison to the first test.

Overall, the FMS is a tool. If one understands that it is designed to test movement and not diagnose the underlying problem, one has a powerful tool.