Date of Award

5-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology

First Advisor

Peter McGinnis, Ph.D.

Second Advisor

Wendy Hurley, Ph.D.

Third Advisor

Joy Hendrick, Ph.D.

Abstract

Purpose was to compare the back squat to the front squat in terms of the peak resultant joint torque (T), peak resultant joint compressive force (CF), and peak resultant joint shear force (SF) at the plane of the L3/L4 spinal junction. The hypothesis was that the back squat would result in a higher peak T, peak CF, and peak SF. The participants were 20 college-aged students (males = 15, females = 5) who each performed both the back and front squat at 70% of their estimated one-repetition maximum weight. The lifts were video recorded and peak resultant joint torques, peak resultant joint compressive forces, and peak resultant joint shear forces were calculated using static equilibrium equations. Statistical analyses revealed that the back squat resulted in a larger peak T, peak CF, and peak SF. Additional analysis showed that both peak T and peak SF occurred for most subjects when the trunk angle was smaller than that of the front squat. Peak CF was found to occur when the heavier loads were lifted but not found to occur consistently with any given trunk angle. It was concluded that when using the same relative load, the back squat results in a larger peak T, peak CF, and peak SF acting at L3/L4 than a front squat. Results also provide evidence that peak T and peak SF occur when the trunk is less upright, and that peak CF is more likely to occur when heavier loads are lifted, rather than when the trunk is more or less upright.

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