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Lecture 4

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University of Toronto St. George
Nevena Simic

Lecture 4 – Health-Enhancing Behaviors Health-Enhancing Behaviors  After looking at some of the attitudinal and behavioral principles identified in Chapter 3, we are going to look at how these principles may be applied in health-enhancing behaviors - Exercise - Accident prevention - Cancer prevention - Healthy diet - Weight control - Sleep 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 maintain fitness or health.  Four Componenets 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. 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)  Example: planking 2. Isotonic exercise- place resistance on muscles by moving muscle groups; e.g. weightlighting (improves strength & endurance)  Example: push up Lecture 4 – Health-Enhancing Behaviors 3. Isokinetic exercise- place resistance that overloads muscle groups through complete range of motion with variable resistance; need special equipment (best for strength and endurance)  Example: bicycle where you can change resistance to make it like your going uphill  Other two forms are 1. Aerobic 2. Anaerobic  Energy for exercise comes from burning glucose and fatty acids - 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 strengths heart and lungs - - -> improved body’s O2 usage - Ex) Jogging, bicycling, swimming  Anaerobic exercise - High-intensity, short-duration, low-endurance - Creates deficit in O2  Example: sprinting 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 stores in the bond between the second and third phosphate groups  When you take one away you are left with energy.  Your body uses the oxygen you breathe to make ATP. ATP attaches to myosin and forced it to let go off actin.  Nerve impulses set off a biochemical reaction that causes myosin to stick to actin.  The two molecules lock together, pulling the muscles thick and thin filament toward each other. How Does Body Create ATP?  Several different systems to create ATP Lecture 4 – Health-Enhancing Behaviors  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 cells contain a high-energy phosphate compound called creatine phosphate  - Phosphate group is removed from creative phosphate by an enzyme called 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)  Cells splits glycogen into glucose - - -> uses anaerobic metabolism (anaerobic means “without energy”) 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 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 muscles 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 Lecture 4 – Health-Enhancing Behaviors  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 for ATP for several hours or longer Does Type Matter?  Sustained nature of aerobic exercise  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 proential energy that food processes  A gram of carbohydrates has 4 calories, a gram of proteins 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 sugards, 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 ≈ 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 mins - Shoveling snow for 15 mins - Stairwalking for 15 mins  Inactivity = more common among - Women vs. men - Older vs. younger adults - Lower vs. higher incomes and education levels Lecture 4 – Health-Enhancing Behaviors - Aboriginal vs. non-Aboriginal Canadians What Are The Health Benefits of Exercise? 1) Effects on cardiovascular system  Strengthens heart muscles  Lowers blood pressure  Raises high-density lipoproteins levels (good cholesterol) and lowers low-density lipoproteins levels (bad cholesterol)  Improves blood flow  Increases heart’s working capacity  Increases cardiovascular fitness and endurance  Reduce risk of heart attack and/or stroke 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  Increases endorphins  - Morphine-like chemical substances  - D
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