Anterior Cruciate Ligament Reconstruction, Muscle Activation, and Center of Mass During Stair Decent

Faculty Sponsor

Kelly Helm


Arts and Sciences


Exercise Science

ORCID Identifier(s)


Presentation Type

Oral Presentation

Symposium Date

Spring 4-29-2021


This study examined the influence of ACLR on muscle activation and center of mass (COM) in females while performing a descending of stairs task. Muscles targeted were the vastus medialis, vastus lateralis, biceps femoris, semitendinosus and medial and lateral gastrocnemius muscles. The research hypotheses stated that significant differences in individual muscle activation and dislocation in COM would be found between ACLR and non-ACLR participants. The study consisted of 13 participants (injured=7, healthy=6). Surface electrodes (sEMG) were placed on the bellies of targeted muscles. Muscle activity was acquired through Delsys Trigno® Wireless EMG System and analyzed with EMGworks® software. XSens captured the translation of COM. Participants each completed three descending stairs tasks. Root mean square (RMS) values of sEMG signals were normalized to a percentage of each participant’s maximum voluntary isometric contraction (MVIC) for each muscle. A two-sample t-test was performed on COM differences between injured and non-injured. A statistically significant difference was found in dislocation of COM with p=0.01. Another statistically different value was found between the Left Vastus Medialis of ACLR vs. Non-ACLR with p=0.025. The research hypothesis is confirmed with regard to significant differences in translation of COM and with respect to the left vastus medialis. In conclusion, ACLR has a significant impact on muscle activation and shifts of COM when descending stairs. Recommendations for a future study include a larger sample size.

Biographical Information about Author(s)

Riana Gesell is a senior Exercise Science major with a Human Biology minor at Valparaiso University. She is attending graduate school at St. Catherine University to pursue her Doctorate in Physical Therapy in Fall 2021. Her experience as a D1 college athlete who suffered four Anterior Cruciate Ligament Reconstructions inspired her to conduct this study and pursue a career in this expertise.

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