Velocity-Loss Training and Parkinson's Disease

Maximal load that can be lifted in one repetition (1RM) will be assessed in both leg press and chest press exercises. The loads on the testing equipment will be increased across 5 to 7 testing repetitions. The persons 1RM will be the highest load the person can move through the range of motion of the exercise. There are no minimum or maximum scores for this test. The higher the 1RM the stronger the person is. The unit of measurement is kilograms.

This test measures the power a person can produce at maximal speed using loads of 20%, 40%, 60%, 80%, and 90% of 1RM for the chest press and leg press. Power shows how fast a person can do work. There are no minimum or maximum possible values. Higher values indicate better neuromuscular performance. Unit of measure is Watts.

The ten-meter walk test will be used to assess gait velocity. The participants will be asked to walk at usual walking speed and as quickly as possible in a straight line on a 10-meter (m) course marked at 0, 2, 8 and 10 m. On verbal command, participants will start on the 0-m mark and stop when the 10-m mark is crossed. The total time to ambulate from the 2-m mark to the 8-m mark (6 m total) will be timed to the hundredth of a second. Two trials will be performed at each speed, and the average will be documented in meters per second. One-minute recoveries will be provided between trials.

The five-time sit-to-stand test will be used to assess functional lower body strength. The participant will sit with arms folded across the chest and the back against the chair. On a verbal command, the participant will stand up and sit down five times as quickly as possible. Timing begins at the word go and ends when the buttocks touch the chair after the fifth repetition. One practice and two testing trials will be performed. Time will be measured in seconds.

Upon verbal cue, participants will stand up, walk around a cone placed three meters from the front edge of the chair and then returns to a seated position as quickly as possible. Time is measured in seconds.

Upper body power will be assessed using the Seated Medicine Ball Throw test. Participants will sit in an armless chair with their back against the chair back and throw a 6-pound medicine ball from the chest as far as possible at an approximate 45-degree angle. Participants will complete three recorded test attempts. The distance thrown in meters will be measured. There are no minimum or maximum possible values. Greater throwing distances indicate better upper body power.

Muscle thickness will be assessed using B-mode ultrasonography. Three longitudinal-view images will be obtained for each muscle assessed. Muscle thickness will be measured by drawing a perpendicular line from the superficial aponeurosis to the deep aponeurosis at the thickest region of the muscle. Assessments will be performed on selected thigh and upper arm muscles. Muscle thickness is measured in centimeters (cm). Higher values indicate greater muscle thickness.

Muscle quality will be measured using a gray scale. Grayscale values range from 0 to 255 units, where lower values (darker pixels) indicate greater muscle tissue content and higher values (lighter pixels) indicate greater intramuscular fat. The muscle to be tested will be the thigh muscles and the back of your arm. Lower grayscale values indicate better muscle quality.