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More on the Heart. Frank-Starling Law of the Heart. Ability of the heart to stretch and increase the force of contraction. Therefore an increase in the amount of blood that is ejected. Skeletal Muscle Pump.
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Frank-Starling Law of the Heart • Ability of the heart to stretch and increase the force of contraction. • Therefore an increase in the amount of blood that is ejected.
Skeletal Muscle Pump • Rhythmic skeletal muscle contractions force blood in the extremities toward the heart • This aids in venous return • One-way valves in veins prevent backflow of blood
Oxygen Delivery During Exercise • Oxygen demand by muscles during exercise is much greater than at rest • Increased oxygen delivery accomplished by: • Increased cardiac output • Redistribution of blood flow to skeletal muscle
Field Tests of CV Fitness • 12 minute run • 1.5 mile run/walk • Step test • Beep test
Monitoring Your Heart Rate • Carotid artery in the neck • Radial artery in the wrist • Count beats for 10 seconds and multiply the result by 6 to get rate in beats per minute
Developing a Cardio-Respiratory Endurance Program • Setting goals • Applying the FITT equation • Frequency • Intensity • Time • Type of activity
Frequency of Training • Train 3–5 days per week • Beginners should start with 3 and work up to 5 days per week
Intensity of Training • Target heart rate zone • Estimate your maximum heart rate (MHR) • 220 – your age = MHR • 207 - (0.7 X age) = MHR • Multiply your MHR by 65% and 90% • People who are unfit should start at 55% of MHR • Example: 19-year-old • MHR = 220 – 19 = 201 • 65% training intensity = 0.65 X 201 = 131 bpm • 90% training intensity = 0.90 X 201 = 181 bpm
Intensity of Training Ratings of perceived exertion (RPE)
Time (Duration) of Training • Total of 20–60 minutes is recommended • One single session or multiple sessions of 10 minutes or more • Different intensity levels require different durations • High-intensity activity = 20 minutes • Low-to-moderate-intensity activity = 45–60 minutes
Type of Activity • Cardio-respiratory endurance exercises (such as…)
Warming Up & Cooling Down • Warming Up (5–10 minutes) • Muscles work better when warmed up • Redirect blood flow to working muscles • Spread synovial fluid • Cooling down (5–10 minutes) • Blood flow and respiration return to normal
Building Cardio-Respiratory Fitness • Rate of improvement depends on age, health status, initial level of fitness, and motivation • Initial phase (1–4 weeks): 3–4 days per week, low end of target heart rate zone, 20–30 minutes • Improvement phase (2–6 months): 3–5 days per week, middle to upper end of target heart rate zone, 25–40 minutes
Maintaining Cardio-Respiratory Fitness • Continue to exercise at the same intensity on 3 nonconsecutive days per week • If you have to stop, start the program again at a lower level • Cross-training maintains motivation
Hot Weather and Heat Stress • Dehydration = excessive loss of fluid • Heat cramps = sudden development of muscle spasms and pain • Heat exhaustion = heat illness related to dehydration from exertion in hot weather • Heat stroke = a severe and often fatal heat illness characterized by significantly elevated core body temperature
Preventing Heat Illness • Use caution in high heat or humidity (over 80°F and/or 60% humidity); lower your intensity and/or add rest breaks • Exercise morning or evening • Drink plenty of fluids; check weight before and after exercise • Avoid supplements and beverages containing stimulants • Wear clothing that “breathes” • Slow down or stop if you feel uncomfortable
Exercise in Cold Weather • Hypothermia = low body temperature due to exposure to cold conditions • Frostbite = freezing of body tissues characterized by pallor, numbness, and a loss of cold sensation • Prevention: • Don’t stay out in very cold temperatures (consult wind chill values) • Wear appropriate clothing
Be Old • Relative risk of CHD increases with age • Over 83 percent of people who die of CHD are 65 or older.
Heredity influences your cardiovascular fitness • Children of parents (and blood relatives) with heart disease are more likely to develop it themselves. • Genetics is important - pick your parents carefully • High/low responders to training
Be a Man or a Woman • CHD is the number one killer of men and women • Men have a greater risk of heart attack than women do, and they have attacks earlier in life. Why? Estrogen may be protective ***menopausal women are at a greater risk, but still not as high as a man
Unalterable Risk Factors CHD • Age • Family History • Sex
Alterable Risk Factors • Things you can do something about… • But if you want CHD here’s what you’ll need:
CHD Factor - Be fat • Obesity increases CHD risk • Excess weight increases the heart's work. • How much fat is too much? • Males - > 25% • Females > 30% • % Body Fat Tests
CHD Factor - High fat diets • High fat foods increase plaque within arteries and contribute to atherosclerosis • High bad cholesterol (high LDLs) • Low good cholesterol (low HDLs)
CHD Factor High Blood Pressure • High blood pressure forces the heart to work harder • How high is too high?
CHD Factor Be a Smoker • Smokers' risk of developing CHD is 2–4 times that of nonsmokers. • Second hand smoke • Smoking is the single most important alterable risk factor
CHD Factor Be a Type A Personality • Type A personalities are: • High-strung • Achievement-oriented • Aggressive • Time-conscious • Stressed…overeat…smoke…drink alcohol…
CHD Factor Live a stressful lifestyle • No one, lying on their deathbed, has said they wished they had spent more time at the office.
CHD Factor Have Other Diseases… • Diabetes • Ulcers • Obesity
CHD Factor Don’t Exercise • If you get the urge to exercise, lie down until the feeling passes. • Many obese and overweight people may have difficulty losing weight. But by losing even as few as 10 pounds, one can lower heart disease risk.