Chapter 7 Part 3. Nutritional Status Inadequate nutrition ◦ Lethargy ◦ Early fatigue ◦...
Transcript of Chapter 7 Part 3. Nutritional Status Inadequate nutrition ◦ Lethargy ◦ Early fatigue ◦...
Nutritional Recommendations for the
Physically Active PersonChapter 7
Part 3
Nutritional Status
Inadequate nutrition◦ Lethargy◦ Early fatigue◦ Irritability◦ Poor training and competitive performance◦ Increased incidence of injury◦ Infection ◦ Excessive weight fluctuations
A low-carbohydrate diet rapidly compromises energy reserves for vigorous physical activity or regular training.
Carbohydrate Intake
Training diet for physically active◦ Adequate refueling day to day◦ Recover between daily sessions
Multiple workouts◦ Nutritional strategies
> 90 min – CHO becomes limiting factor
Nutritional Status
Optimum diet for most sports◦ CHO contributes 60-70% of total energy intake
After each bout of exercise◦ Sufficient CHO to replenish glycogen stores
Maximize subsequent performance
Position Stand
CHO – after exhaustive exercise◦ 50 g every 2 h◦ Moderate and high glycemic foods◦ Goal – 600 g in 24 h
Position Stand (cont)
Recommendations 6-10 g CHO/kg BM/day
Endurance training 10 g CHO/kg BM/day
This is quite a bit of food 70kg person = 2800 kcal of CHO
CHO Intake
Tour de France◦ 6 h per day◦ 12-13 g/kg body weight/day◦ Close to 4000 kcal of CHO/day
CHO Intake
More recently◦ 1.0-1.8 g/kg BM/hr◦ Feedings every 15-60 min◦ Still over 3000 kcal of CHO/d
CHO Intake
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
Timing of CHO Intake
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?
Exercise Effects on Vitamin Needs
B complex◦ Coenzymes in reactions during catabolism
Fat, CHO, protein◦ Vitamin B6 or Thiamin
Vitamin C◦ Negligible effects on endurance
Vitamin E◦ Deficiencies impair muscular function◦ No benefit with excess consumption
Vitamins and Performance
50 years of research Fail to support vitamin supplements to improve
performance aerobic and anaerobic exercise
Vitamins and Performance
Daily supplements of vitamin C 500-1500 mg of per day
May reduce infections Glutamine
Fuel for the immune system Supplementation reduces the risk of infection
Vitamins and Performance
Most often occur in:• Vegetarians • Groups with low energy intake • Elimination of one or more food groups • Individuals who consume
Processed foods Simple sugars - low micronutrient density
Vitamin-Mineral Deficiencies
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
Megavitamins
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
Megavitamins
Aerobic exercise metabolism increases the production of free radicals.
Antioxidants:• ß-Carotene • Vitamin C• Vitamin E• Selenium, copper, manganese, and zinc • Coenzyme Q10
Antioxidants
Vitamin E deficient animals◦ Reached exhaustion earlier
Sufficient Vitamin E◦ Reduced oxidative damage to muscle fibers
Vitamin E
Vitamin E
Innate ◦ Skin and mucous membranes◦ Body temperature◦ Specialized defenses
Natural killer cells, diverse phagocytes, and inflammatory barriers
Immune System
Immune System
Continuous barrier◦Protection ◦Dead cells on outside
The Skin
Acquired immune system Specialized B (bone)- and T (Thymus)-lymphocyte
cells. B cells
Produce antibodies T cells
Cytokines and toxic granules
Exercise Immunology
Theoretical Model
Moderate exercise• A bout of moderate exercise boosts natural
immune functions and host defenses for up to several hours.
Exercise Intensity and the Immune System
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.
Exercise Intensity and the Immune System
Exercise Intensity and Risk of Infection
Excessive sweating Loss of body water and related minerals.
Mineral loss Replaced with well-balanced meals.
Single-mineral supplementation Potential adverse consequences.
Minerals
Strenuous exercise may increase excretion of the following four trace elements: • Chromium• Copper• Manganese• Zinc
Trace Minerals and Exercise
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.
Exercise and Food Intake
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
Exercise and Food Intake