J. Wadner1, D. Kirk2, K. Kunz2, N. Martonick1

1University of Idaho, Moscow, ID; 2University of Washington School of Medicine, Seattle, WA.

The Functional Movement Screen (FMS™) recently introduced the ankle clearing test to measure passive ankle dorsiflexion (PAD). Limitations in PAD may result in reduced squat depth, decreased frontal plane stability at the pelvis, and increased trunk flexion when squatting. However, evidence for whether PAD is associated with movement mechanics during single leg (SLS) and double leg squats (DLS) remains inconclusive. PURPOSE: To assess whether PAD is correlated with frontal and sagittal plane kinematics during the SLS and DLS. METHODS: Participants (n=10) identified as having functional dorsiflexion restrictions during the FMS™ double leg squat were included in the study. This was determined by participants having an improved movement pattern when using the FMS™ kit as a heel lift. All kinematic variables were assessed with inertial measurement units (IMUs). A pressure plate was used to determine when the heel of the assessed leg came off the ground during the ankle clearing test. Sagittal plane kinematics at the ankle, knee, and trunk were evaluated for the DLS. For the SLS, sagittal plane kinematics at ankle, knee, as well as frontal plane motion at the knee and pelvis were evaluated. Kinematics were evaluated as discrete variables at the moment of peak knee flexion. Separate linear models were used to calculate correlations between PAD and kinematic variables during the movement tasks. RESULTS: A moderate negative relationship was found between PAD and trunk flexion during the DLS (r2=0.44, p=0.05). Statistically significant positive correlations were found between PAD and dorsiflexion during the DLS (r2=0.82, p<0.01) and SLS (r2=0.69, p<0.01), as well as for knee flexion during both tasks (DLS: [r2=0.62, p=0.01], SLS: [r2=0.46, p=0.03]). No correlations were found between PAD and frontal plane kinematics during the SLS. CONCLUSION: The current findings support the premise that PAD impacts functional movement at the ankle and up the kinetic chain. These findings indicate that activities done to increase passive dorsiflexion may have the potential to improve parameters of functional movement in the sagittal plane. However, these results do not indicate that PAD is a factor that impacts frontal plane motion at the knee or pelvis.

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