Date of Award
Doctor of Physical Therapy (DPT)
Electromyography; Exercise Therapy -- methods
Knee pain and injury are a commonly seen diagnosis in physical therapy practice. Closed kinetic chain activities are frequently used to treat these diagnoses, because of their safety and functional properties. However isolation of specific muscles is difficult with closed kinetic chain exercises. The researchers chose to further study closed kinetic chain exercises in order to compare traditional closed kinetic chain exercises with a recently developed closed kinetic chain device. The purpose of this study is to assess EMG activity of the quadriceps and hamstrings during two different closed kinetic chain activities of the knee, one a traditional method and the other a new, untested device. The first is a traditional wall slide, consisting of the participant leaning with the back on the wall and squatting. The second is a squat using a closed kinetic chain device (CCD) that holds the leg below the knee stationary.
Seventeen healthy subjects between the ages of 22-26 years of age, mean age of 23.5, performed a maximal voluntary contraction (MVC) and 2 trials of each exercise. EMG activity of the quadriceps (vastus medialis and vastus lateralis) and hamstrings (semitendinosus and biceps femoris) was recorded through surface electrodes. This data was then normalized to percent MVC by comparing the muscle activity in the trial with the muscle activity in the reference MVC.
Results of this study showed a significant difference in % MVC between exercises in the vastus medialis, vastus lateralis, and semitendinosus. There was no significant difference in the % MVC for the biceps femoris.
In conclusion, the CCD resulted in a higher % MVC in the quadriceps than the wall slide. It also resulted in a decrease in the % MVC of the semitendinosus as compared to the wall slide.
Hanson, Linda K.; Salz, Shauna T.; and Steffes, Suzanne L., "An electromyographic study of the quadriceps and hamstrings recruitment during two closed kinetic chain activities" (2005). Physical Therapy Scholarly Projects. 193.