physiology of exercise
TRANSCRIPT
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PHYSIOLOGY OF EXERCISEPPL 30MFall 2012
Mr. Del Duca
Monday, November 12, 2012
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PHYSIOLOGY OF EXERCISE
• physiology is the study of the molecules, cells, organs, and systems involved in maintaining/sustaining life
• we will examine the physiology of exercise, that is, the ways in which exercise can affect different systems of the body
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SOME ORGAN SYSTEMS
• cardio-respiratory - heart and lungs
• neuromuscular - nerves and muscle tissue
• skeletal - bones
• for each system, we will briefly outline the anatomy of the organs, and then examine how exercise affects the system
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• heart and lungs
CARDIO-RESPIRATORY SYSTEM
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PHYSIOLOGY OF THE HEART• the heart consists of 4
chambers: 2 atria, and 2 ventricles
• the heart pumps blood around the body through blood vessels (veins and arteries)
• it has specialized muscle cells that create their own rhythmic beating through electrical impulses
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• heart rate is the measure of how many times your heart beats per minute, and it also a measure of exercise intensity
• with exercise and improved heart fitness, as with any muscle, your heart gets stronger and beats more effectively and efficiently
• each beat of the heart is more powerful, and pumps more blood; it actually gets more flexible, too
• therefore, with any given exercise intensity, your heart beats slower than it would prior to exercising
• in addition, the blood changes with exercise: increased hemoglobin (protein for transporting oxygen) results in better oxygen transport throughout the body
PHYSIOLOGY OF THE HEART
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PHYSIOLOGY OF THE LUNGS
• the lungs consist of a series of “tunnels” that bring air from the outside world into your bloodstream, and vice versa
• they are “opened” and “closed” by a special muscle called the diaphragm
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PHYSIOLOGY OF THE LUNGS
• during exercise, breathing rate is increased, and oxygen uptake and usage can increase by up to 20x
• this is due to an increase in ventilation (breathing rate), better oxygen diffusion into the blood at the alveoli (more hemoglobin), and better oxygen uptake by cells (muscle cells - more on that later)
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NEUROMUSCULAR SYSTEM
• neuromuscular system consists of all the parts involved in voluntary movement:
• brain, nerves (neurons), muscles
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PHYSIOLOGY OF THE NEUROMUSCULAR SYSTEM
• specific part of the brain is responsible for movement: motor cortex
• signals originate here (under influence of other parts of the brain), and are sent down spinal cord to muscles around the body
• involuntary movement (breathing, heart beat) is under different control
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BRAIN IMPROVEMENTS WITH EXERCISE
• with training, your brain becomes more efficient at sending signals to your muscles:
• neuron networks are rearranged, so that signals are sent faster, and are more coordinated
• “muscle memory” is actually the result of improved brain function - certain movements become automatic, originate in spinal cord rather than in brain
• improved reaction time - signal is more direct from brain to muscles
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NERVES AND NEURONS
• nerves are simply bundles of neurons, and neurons are simply long cells that transmit electrical signals from the brain
• with exercise, neuromuscular junctions become more efficient at regulating the signal strength and duration (greater coordination and precision of movements)
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MUSCLES AND MUSCLE CELLS
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MOTOR UNITS
• a motor unit is simply one nerve and all the muscle fibres that it innervates (connects to)
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MUSCLE FIBRE TYPE
• muscles fibres are broken down into 3 categories: type I fibres (slow twitch), type IIa and IIb fibres (fast twitch)
• type IIa and IIb can produce significantly more power (strength and speed); up to 10x more than type 1
• research suggests that training can change the distribution of type IIa and IIb, whereas type I is permanent
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PHYSIOLOGY OF MUSCLE CELLS
• there are MANY training-induced changes that can be made to muscle tissue, including:
• increased vascularization (more blood vessels) resulting in:
• greater oxygen and glucose delivery, greater waste removal
• greater number of muscle fibres AND greater size of each muscle fibre = greater force production
• greater number of motor units recruited = greater force production
• more coordinated motor unit recruitment (fast twitch muscle fibres activated faster with training)
• more mitochondria in each muscle cell = more efficient use of oxygen = less lactic acid = less fatigue
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KEY POINTS
• although exercise in general can increase fatigue resistance in muscles, different types of training can modify your muscles ability to continue to perform that particular activity
• example: aerobic training can increase the enzymes responsible for using oxygen to provide energy (ATP)
• this is called the SPECIFICITY PRINCIPLE (your body will perform better at the things you train it to do)
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PHYSIOLOGY OF BONE
• bone consists of a very hard crystallized structure and different types of cells and blood vessels that maintain its amazing structure and function
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PHYSIOLOGY OF BONE
• stem cells differentiate into different types of blood cells in the marrow
• osteoblasts create the crystal matrix, osteoclasts break the matrix down - constant remodelling
• bones allow for muscle attachment, and are protected at joints by cartilage and other structures
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CHANGES IN BONE (& CONNECTIVE TISSUE)
• with exercise (especially resistance training), there are several important changes that occur in bone
• greater bone density - less likely to develop osteoporosis
• greater ligament and tendon strength
• faster healing - broken bones, torn ligaments, etc.
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TAKE HOME POINTS
• the body has an amazing capacity for regeneration/repair - it is constantly breaking down and rebuilding all the molecules in our body -- exercise makes the rebuilding process more efficient
• specificity in adaptation - your body will get better at doing the things you train it to do:
• supplying blood and oxygen through cardiorespiratory system
• coordination of neural signals leading to voluntary movement
• muscular adaptations to exercise - strength, fatigue resistance/endurance
• increased bone density/more efficient repair of damaged connective tissue
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