Author

Sweet

Date of Award

4-1998

Degree Name

Master of Arts

Department

Human Performance and Health Education

Department

Health, Physical Education & Recreation

First Advisor

Dr. Roger Zabik

Second Advisor

Dr. Mary Dawson

Third Advisor

Dr. Patricia Frye

Access Setting

Masters Thesis-Open Access

Abstract

Analyses of 3 knee extensors, vastus medialis, rectus femoris, and vastus lateralis, were conducted to examine the reliability of (a) maximal voluntary isometric contraction (MVIC) across trials (2), days (5), and joint angles (5); and (b) normalized EMG responses during dynamic knee extension at 2 submaximal work loads. Strength (cable tension) and integrated peak EMG (surface electrodes) were measured during the MVIC. Subjects (N = 44) performed 2 consecutive MVICs with 2 min rest between trials at 110°, 90°, 70°, 50°, and 30° of knee flexion, followed by 2 submaximal dynamic knee extension exercises. Intraclass correlation (R) values for the average scores across trials or days were calculated. For the MVIC peak EMG measures, reliability was higher for the mean of 2 trials than for a single trial; the highest R occurred at 30° of knee flexion. For all muscles and joint angles, the reliability of the mean of MVIC peak EMG scores for 5 days was higher than the reliability for a single day. The lowest R values occurred on Day 1, yet comparable R values occurred on Days 2-5. The R values for normalized dynamic EMG scores were lower and more random than the R values of the MVIC peak EMG scores for trials, days, angles, and loads.

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