Altered Vertical Ground Reaction Forces in Participants With Chronic Ankle Instability While Running.
BACKGROUND
Altered gait kinetics may increase the risk of long-term injuries in participants with chronic ankle instability (CAI). Vertical ground reaction forces (vGRFs) can provide insight into how body loading is altered.


OBJECTIVE
To compare the components of vGRFs while running in participants with or without CAI.


METHODS
Cohort study.


METHODS
University biomechanics laboratory.


METHODS
Twenty-four experienced, college-aged runners. Groups were categorized by the presence (CAI group) or absence (control group) of CAI through self-reported questionnaires.


METHODS
After a warm-up period, all participants ran on an instrumented treadmill for 5 minutes at 3.3 m/s. Data were collected during the last 30 seconds. Five continuous trials of heel-to-toe running were identified per participant and averaged for statistical analysis.


METHODS
The dependent variables were impact peak force (N/body weight [BW]), active peak force (N/BW), time to impact peak force (milliseconds), time to active peak force (milliseconds), and average loading rate ([N/BW]/s).


RESULTS
A difference was found between groups (P = .002). The CAI group had higher impact peak forces (P = .001) and active peak forces (P = .002) compared with the control group. The CAI group also had an increased loading rate (P = .001) and a shorter time to reach the active peak force (P = .001) compared with the control group. No difference was seen between groups in the time to reach the impact peak force (P = .952).


CONCLUSIONS
Participants with CAI produced altered vGRFs and loading rates while running. Altered loading rates could predispose individuals with CAI to stress-related injuries and repetitive sprains.
School of Biological and Population Health Sciences, Oregon State University, Corvallis.
John
J
Bigouette
School of Applied Health Sciences and Wellness, Ohio University, Athens.
Janet
J
Simon
School of Public Health, University of Evansville, IN.
Kathy
K
Liu
School of Public Health, Indiana University, Bloomington.
Carrie L
CL
Docherty
D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D015331:Cohort Studies; D005080:Exercise Test; D005260:Female; D005684:Gait; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D008297:Male; D012420:Running / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology; D055815:Young Adult
biomechanics; gait; kinetics; stress fractures