Award Date

5-1-2016

Degree Type

Dissertation

Degree Name

Doctor of Physical Therapy (DPT)

Department

Physical Therapy

Advisor 1

Carrie Gillis

First Committee Member

Merrill Landers

Second Committee Member

Kai-Yu Ho

Number of Pages

39

Abstract

Background and Purpose: It is claimed that wearing weightlifting shoes with a raised-heel can improve posture and leg muscle activation, and reduce the risk of back injuries during a barbell back squat. However, these proclaimed biomechanical effects have not been thoroughly investigated. The purpose of this study was to compare the thoracic, lumbar, and lower extremity biomechanics during barbell back squat in 3 foot posture conditions. Subjects: 14 healthy recreational weightlifters (7 male and 7 female) between the ages of 18-50 participated in the study. A minimum of 2 years weightlifting experience and regular training with the barbell back squat were required to participate in the study. Methods: The study was conducted on two separate days. The participants' 1-RM (1 repetition maximum) was established during Day 1. Day 2 took place at least 24 hours after, in which participants performed barbell back squats in three different conditions (barefoot on a flat surface, barefoot on a raised-heel surface, and wearing raised-heel weightlifting shoes) at 80% of their 1-RM. The order of performing the lifts under the 3 different conditions was randomized. Surface Electromyography (EMG) used to assess the activation of the knee extensors (vastus lateralis) and paraspinal muscles at L3 and T12/L1 spinal levels. A 3D motion capture system and wireless electronic goniometer recorded the kinematics of the thoracic, lumbar spine, and knee during the squat movement to a depth where the hip is at least at the same level to the knee. A one-way repeated measures ANOVA was used to assess the effects of foot posture conditions on the biomechanical variables of interest. Results: Results indicate that a raised-heel foot posture did not significantly affect trunk and lower extremity muscle activation [thoracic paraspinal (p=0.52), lumbar paraspinal (p=0.179), vastus lateralis (p=0.507)] or the trunk angles at terminal depth of the squat [thoracic spine (p=0.348), lumbar spine (p=0.283)]. Discussion: Our study demonstrates that foot posture does not significantly affect trunk and knee postures as well as the spinal and knee extensor muscle activations during the barbell back squat. Wearing raised-heel weightlifting shoes during the barbell back squat is unlikely to provide significant protection against back injuries for recreational weightlifters.

Keywords

Powerlifting; Injury; Footwear; Resistance training

Disciplines

Physical Therapy

File Format

pdf

File Size

36.708 Kb

Degree Grantor

University of Nevada, Las Vegas

Language

English


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