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What is Physical Fitness?Definition• the ability to perform moderate to vigorous
levels of physical activity without undue fatigue and the capability of maintaining this level of activity throughout life (ACSM)
Components: Cardiorespiratory Fitness Muscular Strength Muscular Endurance Flexibility
Physical Activity vs. Exercise
Physical Activity– any body movement carried
out by skeletal muscles and requiring energy
Exercise– a subset of physical activity
that is planned, structured, repetitive movement of the body designed to improve or maintain physical fitness
Benefits of Regular Physical Activity
Exercise is one of the most important things you can do to improve your
wellness!
• sedentary individuals have 50% more health problems that active individuals including increased risk of:
• hypertension• diabetes• obesity• hyperlipidemia• osteoporosis
Benefits of Physical Fitness• improved sleep• nutritional health• healthy body composition• healthy bone mineral density• improved immune function• reduced risk of CVD, Type II diabetes, some cancers• reduced stress and anxiety• improved self-esteem and lowered risk of depression• improved cognitive functioning, alertness and memory• injury reduction and low back pain• greater longevity and quality of life
* Recommendations from the WHO & the Institute of Medicine
Becoming more active…How much is needed to reap health
benefits?• 60 minutes of moderately intense physical activity every
day*
Is Lifestyle Physical Activity enough?• increased lifestyle physical activity promotes improved
health and well-being but does not necessarily improve physical fitness
• exercise programs designed to improve physical fitness contribute to even greater improvements in quality of life and greater reductions in disease and mortality risk
http://www.phac-aspc.gc.ca/pau-uap/fitness/pdf/guideEng.pdf
Increase Strength Activities
Increase Flexibility Activities
Increase Endurance Activities
days a weekContinuous activities for your heart, lungs, and circulatory system.
days a weekGentle reaching, bending, and stretching activities to keep your muscles relaxed and joints mobile
days a weekActivities against resistance to strengthen muscles and bones and improve posture
Reduce sitting for
long periods
4 - 7
4 - 7
2 - 4
Sources of Energy for Physical Activity
• physical activity increases the energy needs of working tissues including the muscles and the heart…where does this energy come from?– ATP & CP– Carbohydrate: Glucose/Glycogen– Fat– Protein
1. ATP & CP
• very small pool of ATP available in cells
• CP (creatine phosphate) can release phosphate which combines with ADP to form ATP
• supplies are limited, fuels activity for 3 - 15 seconds of maximal effort
• anaerobiccreatine phosphate + ADP creatine + ATP
exercise
rest
2. Carbohydrate: Glucose• derived from muscle & liver glycogen
stores• fuels activities of extreme intensity (20 s
to 3 minutes):– oxygen needs of muscle exceed the
ability of cardiovascular system to supply oxygen
– glucose is used anaerobically (without oxygen) to produce ATP
– by-product is lactate
2. Carbohydrate: Glucose
• in activities of high intensity (3 to 20 minutes):– glucose is used AEROBICALLY (with
oxygen) to produce ATP• in activities of moderate intensity (> 20
minutes):– glucose oxidation is supplemented
with fatty acid oxidation
3. Fat Metabolism• initially during exercise blood [fatty acid]
decreases• after 20 minutes there is an increase in release
of fatty acids from stores– due to hormone epinephrine (adrenalin)
• endurance training produces adaptations that enhance the ability to burn fat ’d size & number of mitochondria in muscles ’d number of capillaries to supply oxygen &
nutrients to muscles
4. Protein
• not a primary fuel for physical activity• contributes about 5 - 10% to energy
expenditure both during activity and at restFactors that influence protein use during
activity:– high dietary protein– increased duration of activity – increased intensity of activity – increased training (especially
strength training)
increase use of protein as a
fueldecrease use of protein as a
fuel
increased duration, decreased intensity
fatty acid oxidation
glucose utilization
decreased duration, increased intensity
fatty acid oxidation
glucose utilization
Effect of Intensity & Duration on Fuel Use
Summary…
Duration Intensity Preferred Fuel Source
8 – 10 seconds EXTREME
20 sec – 3 min VERY HIGH
3 – 20 minutes HIGH
> 20 minutes MODERATE
ATP - CP
anaerobic glycolysis
aerobic glycolysis
fatty acid oxidation
Note: all energy sources are used to some extent at all times
Effect of Diet on Physical Endurance
Maximum Endurance Time
• fat and protein diet
• normal mixed diet
• high carbohydrate diet
57 min
114 min
167 min
Diet to Support Physical Activity
Water• nutrient required in largest amounts by the
body• needs increase during physical activityBody can lose water in four ways:
– urine– feces– sweat– respiration
**
* Loss increases during physical activity
Water & Temperature Regulation
• heat production increases 15-20x during exercise compared to rest
• body cools itself by sweating– 1 L of sweat dissipates about 600 kcal of heat– prevents an in body temperature of about 10°C
• EVAPORATION of sweat cools the body• blood is rerouted through capillary beds that lie just
beneath surface of skin to cool the blood• endurance athletes can lose 1.5 L of water or more
during each hour of activity
Lance Armstrong said blistering temperatures and not drinking enough fluids gave him a challenging day in the saddle during the 2003 Tour de France's 12th-stage time trial, won by German rival Jan Ullrich.
Water & Temperature Regulation
• in hot humid weather, need for water ’s even more
• dehydration not only decreases performance but can cause dizziness, cardiac arrhythmias, muscle spasms, delirium, and death
Hydration Schedule
2 hrs before 400 – 600 ml
15 min before 250 – 500 ml
every 15-20 min during 150 - 350 ml
after exercise 500 ml for each lb body weight lost, or 1.5x body weight lost
Water & Temperature Regulation
Too much water?• leads to a condition called HYPONATREMIA• symptoms include swelling, weight gain, nausea,
and dizziness• may occur in events where individuals replace more
water than they lose and do not replace electrolytes causing dilution of sodium in the blood
Electrolytes
• in addition to contributing to water loss, sweat also results in loss of electrolytes– electrically charged minerals– Na+, K+, Cl-, and Mg2+
• minerals are important for water balance• losses normally replaced through diet
– for exercises lasting longer than 1 hour, replacement of fluids with water & electrolytes may provide a performance advantage
– more important for athletes in competitions lasting 4+ hours with heavy sweating
Replenishing Energy DURING activity…
• during endurance activities lasting longer than one hour, glycogen supplies risk depletion
• maintaining blood glucose levels can prolong time to exhaustion
• glucose replacement (200 kcal) useful in activities lasting longer than 1 hour
• sports drinks with 6 - 10% carbohydrates (50 - 100 kcal per cup)
• depends on goal of exercise!
Replenishing Energy AFTER activity…
• a high carbohydrate meal eaten within 15 minutes accelerates rate of glycogen storage by 300%, called “glycogen window”
• Are energy bars or drinks necessary?
Protein in the Athlete’s Diet
• athletes have increased need for protein due to need to repair and build muscles after activity (max 2.0 g/kg body weight)
• see Table 13.4 for recommended intakes• protein intake after exercise helps replenish
glycogen storesToo much protein? Risks of Supplements:
– dehydration– displacement of carbohydrates from diet, insufficient
replenishment of glycogen stores– kidney problems
Fat Intake and the Athlete
• Fat intake should not be overly restricted. There is no performance benefit in consuming a diet with less than 15 percent of energy from fat. Extreme fat restriction limits food choices, especially sources of protein, iron, zinc, and essential fatty acids.
• Sports nutritionists recommend that any extra fat calories come from monounsaturated and polyunsaturated sources.
Vitamins and Minerals• many vitamins and minerals are important for energy
metabolism• deficiencies impair performance• extra from supplements DO NOT enhance physical
performanceIron• physically active young women prone to iron
deficiency• multiple contributing factors• supplementation should be based on blood tests, not
self-assessment