Carbohydrate Supplementation to improve exercise performance

1
Carbohydrate Supplementation to improve exercise
performance

• What does the research show?
• Linear relationship between performance and
  amount of CHO in the diet
• Glycogen depletion and hypoglycemia appears to
  limit performance and cause fatigue in activities
  gt 60 minutes
• Inadequate recovery leads to glycogen depletion
• Therefore, want to maintain as high as muscle
  glycogen stores as possible

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Carbohydrate Supplementation to improve exercise
performance

• Carbohydrate intake recommendations
• Sedentary individuals 4.5g/kg BW/day (55)
• Physically active individuals 8g/kg/day (60)
• Endurance Athletes 8.5-12.5 g/kg/day (60-70)
• With training, you get increased amounts of
  glycogen/kg muscle
• Leg glucose uptake (mmol)
• During mild exercise 25-50
• During severe exercise 75-90

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Carbohydrate SupplementationThe Glycemic Index

• High glycemic versus low glycemic carbohydrates
• All foods compared to glucose or white bread
• High G.I foods rapidly raise and lower blood
  glucose insulin levels (gt100) quick
• Low G.I foods are much more regulated b/c they
  produce the desired slow release of glucose and
  insulin (lt60) slow
• Categorizing high versus low GI carbohydrates
  does NOT involve using the simple/complex
  categories
• (depends on the speed at which foods are digested
  and absorbed)

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Carbohydrate SupplementationThe Glycemic Index

• High syrup, honey, bagel, baked potato,
  glucose, sucrose, instant rice, pretzels, Corn
  Chex
• Moderate whole grain bread, spaghetti, oatmeal,
  Macaroni Cheese, ice cream, muffins, chocolate
• Low yogurt, peanuts, peas, beans, fructose,
  pears, peanut MMs, apple, vermicelli

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Carbohydrate Supplementation

• Pre- Exercise
• Goal Maximize liver and muscle glycogen stores
• Ideal for athlete to have high amounts of muscle
  glycogen all the time (60-65 complex CHO in the
  diet)
• Carbo Loading 3 days of high complex CHO diet
  prior to event
• 2-3 hrs prior to the event meal consisting of
  slowly digested carbs (e.g. whole wheat, fiber,
  and/or low glycemic index), low-fat and
  low-protein
• barley, yogurt, beans, spaghetti, peanuts
• 30-60 min prior Exercise-Induced Hypoglycemia
• Timing of the feeding (increased insulin levels
  increased insulin sensitivity)
• 5 min prior CHO ingestion immediately before
  exercise has been shown to improve performance
• Exercise increases counter-regulatory hormones so
  no longer threatened by E-I hypoglycemia

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Carbohydrate Supplementation

• During Exercise
• Goal Maintain blood glucose levels for use as
  energy
• Attenuates fat mobilization utilization
• lt 60min 4-6 oz of water every 15-20 is adequate
• gt 60 min 4-6 oz of fluid with 7-9 CHO solution
  every 15-20 min (starting around 30-45 min)
• Sports drinks
• Diluted cola
• 30-60 gm/CHO/hr
• Energy gels
• Bananas
• Orange slices

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Carbohydrate Supplementation

• Post-Exercise/Competition
• Goal Resynthesize glycogen and hasten recovery
  (first 2 hours are critical)
• Within 30 min post-exercise Consume 80-100g high
  glycemic index carbohydrates (absorbed rapidly)
• bagel, cereal, rice cakes, watermelon, dates
• Within 2 hrs post-exercise Consume a meal with
  100-120g CHO repeat every 2 hr as necessary
• Adding protein in the diet may help with
  restoration of muscle glycogen (calories)
• Glycogen repletion can take several days

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Dietary Protein Intake

• Recommendation
• 12-15 of total kcals from proteins
• 0.8-1.0 g/kg/day for average person (75 kg 75
  g)
• 1.2-1.4 g/kg/day for endurance athletes (75 kg
  98 g)
• 1.6-1.7 g/kg/day for strength athletes (75 kg
  127 g)
• Mode strenuous wt training lt5 whereas
  prolonged endurance exercise 15
• Duration protein degradation tends to increase
  after 1 hr of continuous exercise
• Frequency Too frequent of training may result in
  reduced gains in strength and muscle mass.
• Intensity No effect on energy production from
  protein sources

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Increasing Protein Synthesis Interaction of
Training and Nutrition

• Protein synthesis ? increases the amount of
  contractile proteins, making the muscles larger
  and stronger
• Protein synthesis is enhanced
• Following resistance exercise (100)
• When a.a. availability is increased (150)
• When blood insulin levels are high
• Additive synthesis (400)
• Drink containing a.a. CHO 1 or 3 h post

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Protein Supplementation

• Concerns
• Most supplements contain only non-essential amino
  acids (which the body can manufacture itself)
• 12 a.a. can be synthesized in the cells
• 10 a.a must be supplied in the diet (essential)
• Amino acids compete with each other when consumed
  as a supplement
• Lysine is a direct antagonist of arginine and
  serves as a competitor to arginine for entry into
  the brain
• The body cannot absorb more than 30 grams of
  protein at one time, despite the individuals
  body weight or mode of activity
• Extra calories ---gt fat
• Kidney damage, although controversial

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Protein Supplementation

• Bottom line
• If you follow RDA food guidelines, most
  individuals are getting adequate amounts of
  complete protein in the diet (i.e. milk, eggs
  meat)
• Complimentary proteins is also sufficient
• Under most conditions, NO!!
• Exceptions?