Transcript BIOL103 Chapter 11 Sports for Students

Sports Nutrition:
Eating for Peak Performance
BIOL 103, Chapter 11
Nutrition and Physical Performance
• “Exercise is medicine”
• Physical fitness is made up for 5 components:
1.
2.
3.
4.
5.
Cardiorespiratory fitness
Muscular strength
Muscular endurance
Body composition
Flexibility
Figure 11.1 Develop an Active Lifestyle
•
•
To promote health, exercise 30 min/day
To achieve and maintain fitness, 29-60 min of continuous activity or
intermittent aerobic activity, 3-5 days/week
Energy Systems, Muscles, and Physical
Performance
1. ATP-CP energy system:
– Anaerobic: does not require O2
– Quick source of ATP
• Cellular ATP and creatine phosphate
– Fuel for 3 – 15 seconds of maximal effort
Energy Systems, Muscles, and
Physical Performance
2. Lactic acid energy system
– “Acceleration stage”
– Anaerobic
– Breakdown of glucose  ATP and
_______________
– Rise in acidity triggers muscle
fatigue
• How? A rise in acidity  impair
breakdown of glucose and inhibits
____________ binding  muscles
cannot contract
Energy Systems, Muscles, and
Physical Performance
3. Oxygen energy system
– “Endurance stage”
– Breakdown of carbohydrate and
fat for energy in the cell’s
mitochondria
• Requires oxygen (Aerobic)
• Produces ATP more slowly because
….?
Problem Set 11, Q1
• Name the three types of energy system
mentioned in class. Classify them into aerobic
and anaerobic. How does each of the system
acquire energy?
Energy Systems, Muscles, and
Physical Performance
• Teamwork in energy
production
– Anaerobic systems
– Aerobic systems
• Glycogen depletion
– Steady drop of glycogen
for first 1.5 hours
– Entirely depleted at
around 3 hours
Energy Systems, Muscles,
Physical Performance
• Endurance training
– Training increases number of mitochondria 
improves oxygen delivery  enhances aerobic
capacity
– Decreases reliance on anaerobic systems
– Extends availability of glycogen
Muscles and Muscle Fibers
(Problem Set 11, Q2)
• We have two types of skeletal muscles:
– Slow-twitch fibers – muscles that develop tension
more slowly; have high oxidative capacities
• low-intensity, long endurance (aerobic endurance)
– Fast-twitch fibers – muscles that can develop high
tension rapidly.
• High-intensity, short endurance
– Relative proportion determined by genetics
Figure 11.10 Mix of your Muscle Fibers
•
•
If you are best at events requiring explosive movements, you may
have greater percentage of fast-twitch muscle fibers.
If endurance events are your specialty, you may have more slowtwitch fibers.
Optimal Nutrition for Athletic
Performance
• Consume adequate energy and nutrition (first
priority for athletes)
– 6-10g/kg per day of carbs
– 1.2-1.7g/kg per day of protein
– 20-35% of total calories from fat
• Maintain appropriate body weight and body
composition
• Promote optimal recovery from training
• Maintain hydration status
Carbohydrate and Exercise
• High-carbohydrate diets:
– Increase glycogen stores
– Extend endurance
• Carbohydrate loading
– 60-70% of calories as
carbohydrate
– Decrease exercise intensity
prior to competition
– Not very beneficial if the
aerobic activity lasts less
than 60-90 minutes.
Problem Set 11, Q3a
• Explain what is carbohydrate loading and why
it is beneficial to your running.
Carbohydrate intake and Exercise
• Before exercise
– Eating carbs 2-4 hours before morning exercise helps
replenish glycogen stores and improve endurance
– Recommend small portions and easily digested
foods/beverages
• During exercise
– Sports drinks (4-8% carbohydrate + salts/minerals) for
events that last at least 1 hour.
• After exercise
– Replenish glycogen stores: 1-1.5 grams carbohydrate
per body kg both 30 minutes and 2 hours after exercise
Dietary Fat and Exercise
• Fat
– Major fuel source for endurance (aerobic) activities
• Key point: Endurance training increases the capacity of your
oxygen energy system, enhancing your body’s ability to use
fat as fuel.
– High-fat diet not needed
– Recommendations:
• Moderate fat intake: 20-35% of calories
• Limits saturated fat to less than 10% of energy
• Avoid trans fat as much as possible
Protein and Exercise
• Muscles and strength are built with exercise
(not extra protein) and carbohydrates provide
the fuel needed for muscle-building exercise.
• Protein recommendations
– Adults: 0.8 grams per kg body weight
– Endurance athletes: 1.2-1.7 g/kg
– Resistance-trained athletes: 1.6-1.7 g/kg
• Protein sources
– Foods: lean meats, fish, low-fat dairy, and egg
whites
Proteins and Exercise
• Protein intake after exercise:
– Protein combined with carbohydrate consumption
after exercising helps replenish glycogen more
efficiently.
• Dangers of high-protein intake
– Diuresis (loss of body water)
• High protein diets are neither recommended
nor necessary.
Problem Set 11, Q3b
• Should you still consume dietary fat and
protein for your activity? Why or why not?
Vitamins, Minerals, and
Athletic Performance
1. B vitamins
– Needed for energy metabolism
2. Calcium
– Needed for normal muscle function and bones
3. Iron
– Needed for oxygen delivery and energy
production
Fluid Needs During Exercise
• Exercise and fluid loss increase risk for
dehydration
– Increased losses from sweat (0.5-2.0 L/hour)
– Increased with heat, humidity
– Exercise inhibits thirst signal  you probably
won’t take in enough fluid if you wait until you
feel thirsty to replenish your losses.
Fluid Needs During Exercise
• Hydration
– Adequate fluids before, during and after exercise
• Should drink fluid at rates that match sweat rates
– Should you drink water vs. sports drinks?
Characteristics of Nutrition
Supplements and Ergogenic Aids
• Ergogenic aids: substances that can enhance
athletic performance
– Provide calories
– Provide vitamins and minerals
– Contribute to performance and enhance recovery
– Are believed to simulate and maintain muscle
growth
Nutrition Supplements and Ergogenic
Aids
• Table 11.10 Types of Ergogenic Aids
– Nutritional, Physiological, Psychological,
Biomechanical, Pharmacological
• Regulation and concerns about dietary and
herbal supplements
– Bypass FDA safety and effectiveness regulations
– Possibility of product contamination
Nutrition Supplements and Ergogenic
Aids
• Weight-gain powders
– Add an extra 500-1000 calories/day
• 30-50% weight gain by high calorie diet is muscle, rest
is fat
– No proof that increasing protein intake above
recommended levels improves muscle growth
– Too much protein  extra calories  fat
Nutrition Supplements and Ergogenic
Aids and popular theories
1. Creatine – ATP-CP energy system/aerobic
2. Antioxidants – protect muscles/cells from
exercise damage
3. Sodium bicarbonate (baking soda) – to
neutralize lactic acid
4. Chromium – glucose and insulin
5. Iron – for anemia