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Peds 200 last half notes.docx

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Physical Education and Sport
Gordon Bell

The neuromuscular system and exercise Includes the interactions bw our nervous system and skeletal muscleWhen there is a voluntary ability to moveoEfferent nerve impulses are sent from the brain to the muscle and these can be modified by proprioceptors to perform movementFocus will be how the skeletal muscle motor unit MU responds to the effect of acute and chronic exerciseTheMU includes the anterior alpha motor neuron and the muscle fibres it innervates and has been described as the basic functional unit of movementTools commonly used by exercise scientists to study motor unit physiology in humansElectromyography EMGoReflects both the quality and quantity of electrical activity generated during a muscle contractionMuscle BiopsyoRemoval and analysis of a small portion of whole muscleoProvides a direct measurement of muscle fibre morphologymetabolismMorphologyMeasurement of muscle size and the change over timeoIts the only way to directly measure muscleOther toolsoCT scans MRI ultrasoundCan measure the structural components cross sectional area of individual muscles but not individual muscle fibre typeoNear infrared spectroscopy NIR to measure the oxygenation of the muscleHow much oxygen was sucked up to the muscleThe greater the extraction the greater the differenceDevices isokinetic dynamometers and tests vertical jump tests can be used to for measurement of neuromuscular performance outputocan create the most force with isometric movementsMotor UnitsThe anterior aefferent motor neurons are relatively large in diameter and myelinated thus providing fast conduction velocityoMyelinated3560msThe motor neuron leads to the neuromuscular junction aka the motor endplate which includes the interface bw the nerve and the muscle fibreA motor unit is the nerve and muscle fibre it innervatesThere are 3 primary types of MUs in skeletal muscle that have different contractile properties size and type of muscle fibre within the MUo1Fast Fatigable FFFast glycolyticMotor Neurons have large diameters Innervate muscles with large diametersType IIb Type IIx fibre typesSprinters any athletes needing anaerobic systemo2 Fast fatigue resistance FFRFast oxidative glycolytic Motor neurons have Smaller diameterType IIa muscle fibreo3 Slow SMotor neurons have the Smallest diameterMost aerobic muscles may include some FFRType I muscle fibre Humans do not have type IIboOnly have IIx IIa I muscle fibresoIIb is mostly in animalsoMost predominate is IIxMuscle fibreti nerve ratio within a MUoA single motor neuron MN and theof fibres stimulated varies in the bodyGross movementsThey have high musclefibres nerve rationIe Gastroch quads etcFine tuning movementsLow muscle fibre nerve ratioEyeoThe muscle fibres of different MUs can also vary throughout the whole muscleWe can have different MU in one muscleQuadsoFast oxidative glycolytic on the outsideoSlow on the inside Heinemanns size principleoThe small MN will fire first before a large MNSFFRFFVery robust for all voluntary muscle contractionsFFR and FF Have bigger diametersobc they are bigger they can conduct impulses fastermore powerNeed more sodium to influx
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