Transcript Nutritional Recommendations for the Physically Active Person

Chapter 7
Part 3
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Inadequate nutrition
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Lethargy
Early fatigue
Irritability
Poor training and competitive performance
Increased incidence of injury
Infection
Excessive weight fluctuations
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A low-carbohydrate diet rapidly compromises
energy reserves for vigorous physical activity
or regular training.
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Training diet for physically active
◦ Adequate refueling day to day
◦ Recover between daily sessions
 Multiple workouts
◦ Nutritional strategies
 > 90 min – CHO becomes limiting factor
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Optimum diet for most sports
◦ CHO contributes 60-70% of total energy intake
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After each bout of exercise
◦ Sufficient CHO to replenish glycogen stores
 Maximize subsequent performance
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CHO – after exhaustive exercise
◦ 50 g every 2 h
◦ Moderate and high glycemic foods
◦ Goal – 600 g in 24 h
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Recommendations
 6-10 g CHO/kg BM/day
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Endurance training
 10 g CHO/kg BM/day
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This is quite a bit of food
 70kg person = 2800 kcal of CHO
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Tour de France
◦ 6 h per day
◦ 12-13 g/kg body weight/day
◦ Close to 4000 kcal of CHO/day
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More recently
◦ 1.0-1.8 g/kg BM/hr
◦ Feedings every 15-60 min
◦ Still over 3000 kcal of CHO/d
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Highest rates of glycogen storage
◦ First hour post exercise
◦ Activation of glycogen synthase
 Glycogen depletion
◦ Exercise-induced insulin sensitivity
 Permeability of muscle cell to glucose
◦ Storage rates
 7.7 mmol/kg/wet weight/h (first 2 h)
 4.3 mmol/kg/ww/h
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Exercise enhances energy metabolism
Exercise increases total energy expenditure
◦ Is there an increased need, deficiencies of vitamins?
◦ Do athletes have normal vitamin status?
◦ Do athletes require vitamin supplements?
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B complex
◦ Coenzymes in reactions during catabolism
 Fat, CHO, protein
◦ Vitamin B6 or Thiamin
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Vitamin C
◦ Negligible effects on endurance
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Vitamin E
◦ Deficiencies impair muscular function
◦ No benefit with excess consumption
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50 years of research
 Fail to support vitamin supplements to improve
performance
 aerobic and anaerobic exercise
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Daily supplements of vitamin C
 500-1500 mg of per day
 May reduce infections
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Glutamine
 Fuel for the immune system
 Supplementation reduces the risk of infection
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Most often occur in:
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Vegetarians
Groups with low energy intake
Elimination of one or more food groups
Individuals who consume
 Processed foods
 Simple sugars - low micronutrient density
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Contain doses at least 10 and up to 1000
times the RDA
Excess vitamin C = kidney stones
Excess vitamin B6 = liver disease and nerve
damage
Excess riboflavin (B2) = impaired vision
Excess niacin = vasodilatation and inhibition
of fatty acid mobilization during exercise
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Folate = trigger an allergic response
Excess vitamin E = headache, fatigue, blurred
vision, gastrointestinal disturbances,
muscular weakness, and low blood sugar
Excess vitamin A = toxic to the nervous
system
Excess vitamin D = damages kidneys
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Aerobic exercise metabolism increases the
production of free radicals.
Antioxidants:
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ß-Carotene
Vitamin C
Vitamin E
Selenium, copper, manganese, and zinc
Coenzyme Q10
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Vitamin E deficient animals
◦ Reached exhaustion earlier
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Sufficient Vitamin E
◦ Reduced oxidative damage to muscle fibers
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Innate
◦ Skin and mucous membranes
◦ Body temperature
◦ Specialized defenses
 Natural killer cells, diverse phagocytes, and
inflammatory barriers
 Continuous
barrier
◦ Protection
◦ Dead cells on outside
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Acquired immune system
 Specialized B (bone)- and T (Thymus)-lymphocyte
cells.
 B cells
 Produce antibodies
 T cells
 Cytokines and toxic granules
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Moderate exercise
• A bout of moderate exercise boosts natural immune
functions and host defenses for up to several hours.
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Exhaustive exercise
• A prolonged period of exhaustive exercise (and
other forms of extreme stress or increased training)
severely impairs the body’s first line of defense
against infection.
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Excessive sweating
 Loss of body water and related minerals.
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Mineral loss
 Replaced with well-balanced meals.
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Single-mineral supplementation
 Potential adverse consequences.
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Strenuous exercise may increase excretion of
the following four trace elements:
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Chromium
Copper
Manganese
Zinc
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Energy intake needs to be balanced with
energy expenditure.
Regular moderate-to-intense physical activity
 Increase daily energy intake to match their higher
level of energy expenditure.
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Many athletes, particularly females, do not
meet energy intake recommendations.
 Active women (20-60 miles/wk)
 35 kcals/kg BM
 Discrepancies in reported kcals and activity?
 Active become more sedentary when not exercising
 Increased metabolic efficiency
 Expend less energy