Functional Movement Screen Items Predict Dynamic Balance Under Military Torso Load

Musculoskeletal injuries threaten military readiness and impose a significant financial burden. The functional movement screen (FMS), a 7-item, preparticipation screening tool, may aid in identifying compensatory movement patterns that can hinder physical performance and lead to injuries in active-duty military personnel. The primary aim of our study was to determine if items scores from the traditional FMS or a modified FMS (mFMS) obtained under loaded conditions can predict dynamic balance scores while wearing a military load.

Thirty physically active adults (19 males and 11 females) who qualified for Army basic training completed unloaded and loaded FMS testing. Loaded balance was assessed using the Y balance test and the Biodex balance system. The mFMS and both loaded balance assessment protocols included a military load consisting of a standard issue rucksack (M.O.L.L.E.), kevlar helmet, and weighted vest (mass = 24.2 kg).

mFMS item scores were significantly lower than FMS scores for six of the seven movement items. Both FMS and mFMS composite scores were correlated with Y balance scores (FMS: r = 0.53, P = 0.003; mFMS: r = 0.37, P = 0.043). Participants with higher composite scores (≥15) outperformed those with lower composite scores (≤14) for the FMS (P =0.006, d = 1.16) and mFMS (P = 0.031, d = 0.75). Lasso penalized regression analyses revealed that (1) higher unloaded in-line lunge subscores predicted better Y balance scores, (2) loaded trunk stability push-up scores of three predicted worse balance on the Biodex, and (3) unloaded and loaded shoulder mobility scores of 3 predicted better performance on the Biodex balance system.

The in-line lunge subscore from the FMS was the strongest predictor of torso-loaded balance, and the FMS may be more appropriate than a torso-loaded FMS battery when predicting torso-loaded balance among adults with body composition and fitness profiles similar to those of entering military recruits. These findings provide evidence supporting the use of the conventional FMS to identify active-duty personnel who exhibit greater balance deficits and may develop related musculoskeletal injuries while performing operational tasks that require the transport of heavy loads over long distances.