C-Protein in Fatigue and Aging

Volunteers will perform knee extension exercise of the dominant limb while seated in a chair designed for exercise of the knee extensor muscle group. The chair will be equipped with a lever arm, aligned with the axis of rotation of the knee and fixed to the distal shank, 2 centimeters proximal to the ankle joint. The lever arm will be instrumented to provide resistance and measure velocity. The volunteers will perform 3-5 maximum voluntary contractions (MVC) to determine peak torque. Once established, volunteers will rest for 5 minutes before initiating the fatigue protocol, whereby they will perform repeated MVC of the dominant limb against resistance equal to or less than 50% of MVC until range of motion cannot be maintained. Because the goal of this exercise is to uniformly fatigue the quadriceps muscle group, this exercise will be performed continuously. It is expected to take between 1 and 3 minutes to achieve the desired level of fatigue.