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Chapter 13: Fitness and nutrition

Benefits of fitness

  • More sleep, better sleep: body get worn down during exercise, during sleep it grows new cells, gets rid of waste and repairs injury
  • Better nutritional health, you eat more and are more likely to get necessary nutrients
  • Improved body composition: increase in lean tissue, decrease in fat
  • Improved bone density: physical activity builds bone strength and limits osteoporosis

Benefits of fitness

  • Better immunity
  • Lower risk of cancer
  • Better circulation and lung function
  • Lower risk of CVD
  • Lower risk of Type II Diabetes, normalized glucose tolerance
  • Other benefits

What does fitness involve?

  • Flexibility
  • Muscle strength
  • Muscle endurance
  • Cardiorespiratory endurance

How do you become fit?

  • Muscles and cells respond to overload, they grow in shape and size, hypertrophy
  • Muscle will shrink if not used, atrophy
  • All muscles must be worked to be totally healthy, 2-3 days a week
  • Stretching before and after a workout, also on off days
  • Aerobic exercise, 5-7 days per week
  • Rest at least one day out of a week long cycle, two is better

Weight/strength training

  • 2-3 days per week
  • Can lead to muscle strength and/or muscle endurance
  • For strength, lots of weight, low repetitions
  • For endurance, lower weight high number of repetitions

Cardiorespiratory endurance

  • Some comes from weight training
  • Really need maintained increased heart rate, 20 minutes or long
  • Increases the bodies ability to provide muscles with oxygen and remove carbon dioxide, heart and lung endurance
  • Maximal oxygen uptake(VO2max), increase blood volume and red blood cell count= more oxygen
  • Cardiac output increases
  • More blood per beat, stroke volume increases
  • Resting pulse decrease, heart is more efficient (avg is 70bpm)
  • Lower blood pressure

What fuels the body during exercise

  • Glucose, fatty acids, amino acids
  • At rest, more than half from fats
  • Activity means more glycogen use (glucose)
  • Initially comes from muscle, later epinephrin signals liver and fat cells to give up some energy (glucose and fatty acids)
  • High carb diets (fast burning vs slow burning) can help to increase endurance by allowing muscles to work at maximal efficiency (they are not waiting for energy)

How hard you exercise is important

  • Moderate exercise allows oxygen to remain at near normal levels, therefore, aerobic metabolism can take place, fats and glucose used steadily, glycogen conserved
  • Strenuous exercise creates oxygen deficiency, anaerobic metabolism, glycogen reserves depleted quickly

When do you start to use fat?

  • After 20 (actually closer to 1hr) minutes, your body starts to rely on fat for fuel, still uses some glucose from glycogen breakdown
  • After 2 hours, glycogen depletion, nervous system shut down
  • “hitting the wall”

How to keep blood glucose high and recover

  • Regularly drink or eat sugary substances during activity (if longer than 45 min)
  • Eat lots of carbs right after exercise
  • Train muscles to store more glycogen
  • Carb loading diets

Post workout carb recovery

  • Within two hours eat lots of carbs (body stores glycogen in muscle 300% faster, but only within two hours)
  • Trained muscle use glycogen more slowly and fat more quickly

Fat use during a workout

  • Fatty diet tends to impair endurance
  • However, prolonged fatty diets can actually be a benefit, body adapts to use fat first, typical of marathoners, although evidence is slim
  • Fat below 20% is bad too, not enough for endurance energy
  • Need 30% of kcal from fat
  • Fat can fuel hours of activity
  • Fat burn begins almost immediately, comes from fat in muscle and fatty tissues

Intensity/Duration affects fat usage

  • More intensity generally means less fat being used
  • Oxygen must be present for fat use
  • After initial blood fat is used, epinephrine signal for fat release into blood stream
  • After 20 minutes, more blood fat than usual, fat becomes a primary fuel
  • Highly trained muscles use more fat for fuel

Protein use during activity

  • Muscle build fastest right after workout
  • Eating protein (and carbs) right after workout stimulates protein synthesis
  • Slight overload causes muscle breakdown and rebuilding, new muscle better suited for activity that caused overload
  • A typical athlete needs 7-28 g of protein added to the muscles each day

Protein is not a common fuel source for the muscles

  • No more than 10%
  • Carb rich diet curb protein use
  • Aerobic training (more than an hour) uses up glycogen and starts using protein
  • Anaerobic strength training uses little protein during workout but lots right after
  • 0.8g/kg/day normal
  • 1.2-1.7 g/kg/day for athletes that’s up to 120g/day for an average man or 94 for the average woman

Vitamins and minerals

  • A balanced diet negates the need for any supplement
  • Nutrient deficiency can harm performance, but extra has not been shown increase performance
  • It takes a long time to incorporate them into proteins for use
  • Calcium may be the one major exception

Vitamin E and Iron

  • Vitamin E is an antioxidant, some, but not many studies have shown that vitamin E megadoses before high-intensity training can limit oxidative stress in muscles
  • Iron deficiency is bad for performance (less oxygen to muscles), women and herbivores have to watch,
  • Sports anemia, begin training, old blood cells die, blood volume increase, adaptive process

Fluids and electrolytes

  • Temperature regulation
  • Important to hydrate before, during and after activity
  • Even 10% dehydration can result in 50% decreased muscle efficiency and endurance
  • Electrolytes, sodium, potassium, chloride, lost in sweat,
  • Too much loss leads to cramping, vomiting, bloating, seizure, confusion (Hyponatremia: sodium loss)

How much water and electrolytes

  • 2-3c of water 2h before
  • 2 c of water right before
  • 1-2 cups every 15 minutes during
  • 2c for each pound of weight loss after
  • High salt diet prior to competition
  • Sodium rich foods during competition

Diets for active people

  • High nutrient density
  • Unprocessed foods
  • Lots of whole grains, fruits, veggies
  • Lots of carbs (60-70%)
  • 20-30% unsaturated fat
  • 10-20% protein
  • Balanced diet