BIOS252 Week 2 PowerPhys3 Lab Report

LABORATORY REPORT Activity 3: Recruitment and Contractions Name: Instructor: Date: PREDICTIONS 1. When the arm goes from resting to flexing, the amplitude and frequency of sEMG spikes will: increase 2. During flexion, the amplitude and frequency of sEMG spikes will _be more_ during extension. 3. Recruitment of motor units will be greatest when the load is: 20 MATERIALS AND METHODS Comparison of motor unit activation during muscle tone and concentric and eccentric isotonic contractions 1. Dependent Variable amplitude 2. Independent Variable muscle movement 3. Controlled Variables total motor units present in muscle, subjects physical condition Recruitment during isometric contractions 1. Dependent Variable amplitude and frequency of sEMG spike 2. Independent Variable muscle load 3. Controlled Variables total number of motor units present in a muscle, muscle movement, and subjects physical condition 4. What does the acronym sEMG stand for? Surface Electromyography 5. During a muscle contraction, what is recorded on a sEMG? Amplitude in mV and frequency of sEMG spikes 6. Spike numbers were measured during a 200 msec period. RESULTS See Table 3: Muscle Tone (Resting) and Isotonic Contractions See Graph 1: sEMG Amplitudes and Frequencies at Rest and During Isotonic Contractions