Award Date

8-1-2014

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Kinesiology and Nutrition Sciences

First Committee Member

Janet S. Dufek

Second Committee Member

John Mercer

Third Committee Member

James Navalta

Fourth Committee Member

Robbin Hickman

Number of Pages

87

Abstract

The purpose of this study was to investigate lower extremity kinematics and muscle activation patterns in inclined backward walking (IBW) versus traditional backward walking (BW). This purpose was achieved by evaluating performance of individuals walking backward on a treadmill at inclines of 0%, 6%, 8%, 10%, and 12%. Eleven participants (24.9 ± 4.8 yrs, 71.9 ± 11.6 kg, 1.7 ± 0.09m) recruited from the UNLV student body went through a familiarization training program before any data were collected. The familiarization training, which took place across 3 different days, served to: 1) help the participants become comfortable and familiar with BW and IBW, and 2) find each participant's preferred speed of walking at each tested incline. During each training day, participants walked at each incline for five minutes, totaling in 25 minutes of BW and IBW, Participants completed data collection within 1 week of familiarization. Data collection consisted of a warmup followed by attachment of surface EMG electrodes to the right leg to the rectus femoris (RF), tibialis anterior (TA), medial gastrocnemius (MG), and the biceps femoris (BF) muscles. The EMG signals (2000 hz) were recorded with a Noraxon MyoSystem 2000 (Noraxon, Scottsdale, AZ). Maximal voluntary contraction (MVC) exercises for each monitored muscle were performed and recorded. Next, 35 reflective markers were attached (Vicon Fullbody PlugInGait model) for motion capture (200 hz) with a 12 camera Vicon nexus 3D motion capture system (Vicon Motion Systems Ltd, Oxford, UK). Participants next walked for five minutes at each incline (0%, 6%, 8%, 10%, 12%), presented in random order. Stance and swing phase for the left and right lower extremities were determined from kinematic data and average EMG for each muscle and condition was assessed for each phase. Lower extremity ankle, knee and hip joint kinematic parameters included position, velocity and acceleration at initial contact and range of motion during stance and swing. Step rate was also measured. One way repeated measure ANOVAs were conducted for each dependent variable. Pairwise comparisons were conducted between 0% and each incline (α=0.05, Bonferroni correction). Results indicated that as incline increased, preferred speed decreased (0% = 1.00 ± .14 m/s, 6% = 0.96* ± .15 m/s, 8% = 0.95* ± .16 m/s, 10% = 0.92* ± .18 m/s, and 12% = 0.91* ± .18 m/s). The ankle joint angle was different at 10% (p = .048) and at 12% (p = 0.01). The knee joint angle was different at all inclines (6% - p

Keywords

Backward walking; Inclined; Kinematics; Leg – Muscles; Muscle function; Walking; Walking – Physiological aspects

Disciplines

Biomechanics | Kinesiology

Language

English


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Biomechanics Commons

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