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Lecture 4

Health Psychology Lecture 4.doc

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Nevena Simic

Health Psychology: Lecture 4 May 28 , 2012 Health-Enhancing Behaviours- Chapter 4: Exercise: • Physical activity: any skeletal muscle contraction that results in an increased energy expenditure - Any physical activity (even fidgeting) will use energy and burn calories • Exercise: repetitive physical activity or movement aimed at improving or maintaining fitness or health. Four components of physical activity: 1. Type: identifies the physiological systems used in a particular activity (aerobic, strength, endurance, flexibility) 2. Frequency: describes how much activity is performed over a period of time. 3. Intensity: describes load imposed on physiological systems. (Physiological load: how much our systems have to do to control the load, climbing stair is more of a load than a flat surface) 4. Duration: temporal length of physical activity. Does type matter? : • Many different types of exercise or physical activity…but physiologically there are 5 forms of exercise • Resistance related: 1. Isometric exercise: contract muscle group against immovable object without movement in body (improves muscle strength) holding the subway rails, and plank position. 2. Isotonic exercise: place resistance on muscles by moving muscle groups; e.g. weightlifting (improves strength & endurance) push up 3. Isokinetic exercise: place resistance that overloads muscle group through complete range of motion with variable resistance; need special equipment (best for strength and endurance) change in resistance, putting weights on back while doing push ups • Other two forms are 1. Aerobic 2. Anaerobic • Energy for exercise comes from burning glucose and fatty acid. - Can be in the presence of oxygen or not • Aerobic Exercise - Sustained exercise, prolonged oxygen (O2) use - High intensity, long duration, high endurance - Stimulates and strengthens heart and lungs  improves body’s O2 usage - Ex) Jogging, bicycling, swimming • Anaerobic Exercise - High-intensity, short-duration, low-endurance - Create deficit in O2 - Limited resources - Sprint, running fast over short distance Exercise Physiology • Ability to perform physical work is dependent upon the ability of the muscle to transform chemical energy into mechanical energy How exercise works • Muscles: source of energy that keeps everything going is Adenosine triphosphate (ATP) • Biochemical way to store and use energy - Adenine nucleotide bound to three phosphates - Energy stored in the bond between the second and third phosphate groups • Our muscle groups are made out of individual strands of muscle. One strand is made up of many strands and than in those strand there is two proteins called actin and myosin and these help our muscles to contract. How does body create ATP? • Several different systems to create ATP • Work together in phases - Different forms of exercise use different systems, so a sprinter is getting ATP in a completely different way from a marathon runner • ATP comes from three different biochemical systems in the muscle, in this order: - Phosphagen system - Glycogen-lactic acid system - Aerobic respiration Phosphagen System • Muscle contains a high-energy phosphate compound called creatine phosphate • Phosphate group is removed from creatine kinase, and is transferred to ADP to form ATP • ATP levels and creatine phosphate levels= phosphagen system - Supply energy needs of working muscle at a high rate, but only for 8 to 10 seconds Glycogen-Lactic Acid System • Muscles have big reserves of a complex carbohydrate called glycogen (chain of glucose molecules) • Cell splits glycogen into glucose uses anaerobic metabolism (anaerobic means “without oxygen”) to make ATP and a byproduct called lactic acid from the glucose • 12 chemical reactions take place to make ATP under this process, so it supplies ATP at a slower rate than phosphogen system - Produce enough ATP to last about 90 seconds • It is slower than the phosphogen system because there are far many steps and exercise is limited and availability is limited. Aerobic Respiration • When oxygen is present, glucose can be completely broken down into carbon dioxide and water in a process called aerobic respiration • Glucose can come from three different places: - Remaining glycogen supplies in the muscles - Breakdown of the liver’s glycogen into glucose, which gets to working muscle through the bloodstream - Absorption of glucose from food in the intestine, which gets to working muscle through the bloodstream • Can also use fatty acids from fat reserves in muscle and the body to produce ATP • In extreme cases (like starvation), proteins can also be broken down into amino acids and used to make ATP • Aerobic respiration would use carbohydrates first, then fats and finally proteins • Produces ATP at the slowest rate of the three systems • Supply ATP for several hours or longer Does type matter: • Sustained nature of aerobic exercise produces health benefits • Other forms of exercise are satisfying in their own way, but have less effect on overall fitness - Affect short-term glycogen stores instead of long-term energy conversion systems A note on calories: • Number of calories in a food is a measure of how much potential energy that food possesses • A gram of carbohydrates has 4 calories, a gram of protein has 4 calories, and a gram of fat has 9 calories • Our bodies “burn” calories through metabolic processes - Enzymes break carbohydrates into glucose and other sugars, fats into glycerol and fatty acids and proteins into amino acids - These molecules are then transported through the bloodstream to cells, where they are either absorbed for immediate use or sent on to the final stage of metabolism in which they are reacted with oxygen to release their stored energy. Exercise: • Only 49% of Canadians are at least moderately active during their leisure time - Moderate is about 150 calories (kcal) of energy per day, or 1,000 kcal/week - Physical activity that is done at 3.0 to 5.9 times the intensity of rest • Common chores - Washing and waxing a car for 45-60 minutes - Washing windows or floors for 45-60 minutes - Gardening for 30-45 minutes - Wheeling self in wheelchair for 30-40 minutes - Pushing a stroller 1.5 miles in 30 minutes - Raking leaves for 30 minutes - Walking 2 miles in 30 minutes (15 min/mile) - Shovelling snow for 15 minutes - Stair walking for 15 minutes • Inactivity- more common among - Women vs. men - Older vs. younger - Lower vs. higher incomes and education levels - Aboriginals vs. non-aboriginal Canadians What are the health benefits of exercise? : 1. Effects on cardiovascular system (number one cause of illness and death) - Strengthens heart muscles - Lowers blood pressure - Raises high-density lipoprotein levels (good cholesterol) and lowers low- density lipoprotein levels (bad cholesterol) - Improves blood flow - Increases heart’s working capacity - Increases cardiovascular fitness and endurance - Reduce risk of heart attack and/or stroke - Reduce hypertension 2. Effects on weight -Optimization of body weight Prevent/control non-insulin dependent diabetes Prevent obesity 3. Effects on muscle tone - Improved physical work capacity - Improvement/maintenance of muscle tone and strength - Increase in soft tissue and joint flexibility - Prevent back pain - Prevent osteoporosis 4. Effects on psychological health - Improved mood - Reduce depression and anxiety - Help manage stress - Increases Endorphins
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