Term of Award

Spring 2015

Degree Name

Master of Science in Kinesiology (M.S.)

Document Type and Release Option

Thesis (open access)

Copyright Statement / License for Reuse

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.


Department of Health and Kinesiology

Committee Chair

Li Li

Committee Member 1

Thomas Buckley

Committee Member 2

Barry Munkasy

Committee Member 3

Jody Langdon

Committee Member 3 Email



Sport related concussions affect nearly 1.6 to 3.8 million athletes annually in the United States. A large number of these athletes suffer from postural instability following concussion. Postural control assessment has become a recommended tool to determine readiness to return to play. Measurement of postural control through the use of center of pressure (CoP) variables may provide a sensitive evaluation following concussion and throughout recovery. Purpose: To evaluate a unipedal and bipedal quiet stance protocol consisting of linear and nonlinear CoP measurements with varying durations in a concussed population throughout recovery. Methods: Thirteen NCAA Division I Collegiate Football players (age: 20.1 ± 1.6 years, height: 178.3 ± 4.8 cm, mass: 94 ± 10.4 kg) were tested. Participants completed a quiet stance protocol for the first 8 days following injury and at return to play (RTP) under unipedal right and left leg conditions, 3 trials each for 20 s and a bipedal condition (feet together, first 20 s and full 120 s). Three trials of the unipedal stance were conducted and the mean was statistically evaluated. Linear CoP measurements evaluated were Ninety-five percent area (95area) and average velocity (Vavg); nonlinear measurements were approximate (ApEn) and sample (SampEn) entropy. ApEn and SampEn were evaluated in the anterio-posterior (AP) and medio-lateral (ML) directions. These were analyzed using a two way (base of support (BOS) x day) MANOVA as well as a Tukey post hoc analysis. Results: There was a significant main effect for BOS condition, however no main effect for day. No difference was observed between right and left unipedal stances. The 120 s trial and 20 s trial for the bipedal stance was significantly different for 95area, ApEn AP, SampEn AP, and SampEn ML. Discussion: It may be necessary to collect data for up to 120 s to reliably quantify the effects of concussion on the postural control system. In this population, both ApEn and SampEn appear to be dependent on the recording length as well as discriminate different BOS conditions.