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Muscle Function and Aging

Muscle Function and Aging

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Muscle Function and Aging

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  1. Muscle Function and Aging Dain LaRoche, Ph.D

  2. Introduction • Muscle force and power production decrease with aging • Locomotion, fall risk, activities of daily living, and independence • Is the loss of muscle function associated with aging process or physical inactivity?

  3. Muscle Function • Decrease in muscle function due to: • Loss of muscle mass and quality • Decrease in type II (fast twitch) fibers • Inability to recruit motor units • Decreased motor unit firing rate • May affect rate of force development (power) in addition to total force

  4. Motor Unit

  5. Muscle Quantity and Quality

  6. Purpose • To examine the effects of age and physical activity on the determinants of muscle power

  7. Methods • Able-bodied, independent women aged 65-80 years old • Historical physical activity questionnaire and muscle function test will be administered • Cybex Dynamometer and Biopac Data Acquisition System • Force • Electromyography (EMG)

  8. Cybex Dynamometer

  9. Procedure Participants will be secured to the dynamometer for knee extension Surface EMG electrodes will be placed over the vastus lateralis muscle Subjects will maximally extend the knee as quickly as possible following a visual stimulus. EMG will be recorded with Biopac PRO v3.6.7

  10. Visual Stimulus

  11. PMT Stimulus Stimulus Time to Peak EMD Rate of Force Development Integrated EMG Force

  12. Measures • Premotor time • calculated by determining the time from initiation of the stimulus to detection of EMG • Electromechanical delay • determined by calculating the time from the onset of the EMG until the detection of force • Time to peak force • determined by calculating the time from the onset of the stimulus until peak force

  13. Measures • Peak force • the highest force measured • Rate of force development • slope of the force versus time line • Onset EMG • comparison of onset EMG to peak force EMG

  14. Expected Results • Greater in Inactive: • Pre-motor time • Electromechanical Delay • Time to Peak • Lower in Inactive: • Rate of Force Development • Onset to Peak EMG Ratio • Lower Power Output in Inactive!

  15. Next Steps • Subject recruitment and data collection • Power training intervention • Muscle function and aging

  16. Thank You! Johnson State College