Nutrition And Exercise - SPS1111 Lecture 10 - PDF

Nutrition and Exercise Dr. Oliver Barley SPS1111 Week 9  2 Common Dietary Goals – Eat to optimize performance – Eat to optimize body composition  Acceptable Macronutrient Distribution Range Food and Nutrition Board, Institute of Medicine, 2002, Dietary reference intakes for energy, carbo...

Nutrition and Exercise Dr. Oliver Barley SPS1111 Week 9  2 Common Dietary Goals – Eat to optimize performance – Eat to optimize body composition  Acceptable Macronutrient Distribution Range Food and Nutrition Board, Institute of Medicine, 2002, Dietary reference intakes for energy, carbohydrates, fiber, fat, fatty acids, cholesterol, protein, and amino acids (Washington, DC: National Academies Press)  Carbohydrates Primary role of carbohydrates is energy provision – 1 g= 4 kcals Monosaccharides (single sugar molecules; simple sugars) – Glucose Simple Carbohydrates – Fructose – Galactose Disaccharides (two sugar molecules joined by glycosidic bond) – Sucrose – Lactose – Maltose  Carbohydrates Polysaccharides or complex carbohydrates (up to thousands of glucose molecules) – Starch – Fibre – Glycogen Foods high in simple carbs are digested faster and elicit a large insulin response over a short time frame When might be an optimal time to consume simple carbs? – If glycogen stores are full this causes fat deposition  Fibre: The Forgotten Nutrient Diets low in fibre are associated with: – Heart disease – Diverticulosis (bulges in large intestine) – Colon cancer – Diabetes (type 2) For those wishing to lose weight, high fibre diets can help you stay fuller longer in between meals It’s recommended to consume 25 g to 38 g per day  Carbohydrate requirements for optimal performance 50-100 g/day is minimal to prevent ketosis and catabolism Strength/sprint/skill athletes – 5-6 g/kg/day – 100 kg athlete = 550 g CHO/day Endurance athletes (> 90 min/d) – 8-10 g/kg/day – 80 kg athlete = 720 g CHO/day  Fat Essential for life – Temperature regulation – Protection of vital organs- Insulation – Distribution of vitamins- A, D, E, K – Energy production- Break down to glycerol and FFA – Formation of cell membranes (Omega-3, -6) AMDR (acceptable macronutrient distribution ranges) – Between 20 – 35% of energy from fat Based on a 2000 kcal diet – 400 to 700 kcal or 44g to 77g Diets < 15% of kcal from fat may not provide additional health benefits and are hard to follow  Fat is….good?! Type of fat Source Effects on Cholesterol Olives, olive oil, canola oil, peanut oil, Monounsaturated Lowers LDL, raises HDL almonds, peanuts Polyunsaturated Corn, soybean, safflower, fish Lowers LDL, raises HDL Whole milk, butter, cheese, ice cream, Saturated Raises LDL and HDL red meat, coconuts Trans fatty acids Margarine, shortening, fried foods Raises LDL, lowers HDL Two EFAs have been identified Linoleic acid (an omega-6) Primarily found in vegetable oils -linolenic acid (an omega-3) Found mainly in leafy green vegetables, soy, seafood, and canola oil  During EXERCISE: Epinephrine is secreted during exercise, stimulating breakdown of adipose cell triglycerides (TG) → release of free fatty acids (FFA) → blood  During Low Intensity Exercise, 25 % VO2 max: < 20% Total energy cost derived from CHO > 80% total energy cost derived from fat The fat-burning zone?  During Moderate to High- Intensity Exercise Exercise at 65% VO2 max a. Fats & CHO contribute ~ equally Exercise at > 85% VO2 max a. Energy contribution from fats diminishes to < 25% b. Muscle glycogen becomes preferred energy source Fat Metabolism During Exercise Number of factors determine amount/source – Fitness level – Type of exercise – Intensity and duration of exercise – Available fat reserves – Ability to mobilize and transport FA – Composition of meal/diet prior to exercise – Availability of stored CHO or amount of CHO intake during exercise  Do High-Fat Diets Work? Both CHO and Fat important for exercise – Fat predominates during moderate exercise And during long duration exercise Generally speaking, as glycogen decreases FFA use goes up – CHO feeding during exercise moderates this Theoretically, increasing [FFA] could potentially increase use and prolong glycogen and exercise  High Fat Diets and Performance Type of diets used – Single high fat meal before exercise About 4 hr prior…no difference – Short-moderate term (3-5 days, up to 4 weeks) high fat diet before exercise Beneficial for steady-state, moderate intensity exercise, improve fat oxidation and in some cases time to exhaustion – High-fat diet (short or long term) followed by one or two days of high CHO intake prior to exercise Short term followed by CHO seems to work – High fat diets can cause GI distress and are not practical for athletes engaging in high-intensity activity. – Think about how fats are metabolized (high-intensity exercise?)  Protein Proteins are composed of AAs (amino acids) 20 required AAs, 9 essential AAs Functions of protein: – Carry oxygen (hemoglobin) – Support the immune system (antibodies) – Catalyze reactions (enzymes) – Allow muscle contraction (actin, myosin and troponin) – Help to clot blood (prothrombin) – Acts as a messenger (hormones) – Needed for protein synthesis  Protein Foods containing proteins deficient in one or more essential amino acid are said to contain incomplete proteins. Grains, beans, vegetables have incomplete proteins – Soy and quinoa are 2 plant-based proteins that are considered complete. Complementary proteins are contained in a combination of grains, beans, and vegetables to form complete protein sources.  Protein quality The Protein Digestibility Corrected Amino Acid Score (PDCAAS) the currently preferred method for evaluating the protein quality. – This score measures the quality of a protein based on the amino acid requirements of a 2- to 5-year old child.  Protein requirements Sedentary individuals: – Due to cell turnover or the breakdown and regeneration of somatic cells. 0.8g/kg/day Endurance athletes – Due to tissue repair and use of BCAAs for auxiliary fuel 1.2-2.0g/kg/day Strength/power athletes – Due to tissue repair and positive nitrogen balance in muscle for anabolism (muscle hypertrophy) 1.4-2.0g/kg/day Protein requirements  Factors Influencing Protein Requirements Total energy intake Desire to lose or gain weight Carbohydrate availability Exercise intensity and duration Dietary protein quality  Proteins and exercise Protein appears to be a relatively minor source of energy In the later stages of prolonged endurance exercise, protein could contribute up to 15% of total energy cost – What does this mean for endurance athletes? A brief session of high intensity exercise lowers rate of protein synthesis; speeds protein breakdown – Carbohydrates may attenuate this. Increasing exercise intensity on leucine oxidation  Too much Protein?? May lead to – Renal damage Not so much in healthy people – Increased urinary calcium excretion Maybe only in people who use purified protein supplements rather than food – Dehydration increased water loss from additional nitrogen excretion  Vitamins and minerals Vitamins are organic substances that can not be synthesized by the body – A, D, E, K (fat-soluble or absorption aided by fat) – C and B vitamins (water soluble) Minerals are inorganic elements found needed for growth and metabolic processes – Calcium needed for muscle contraction and bone mineralization – Iron needed for oxygen carrier  Vitamins B vitamins assist with energy production and the building and repair of muscle. Vitamin D is required for adequate calcium absorption and the promotion of bone health. Vitamins C and E, β-carotene, and selenium serve as antioxidants and help protect cells from oxidative damage.  Minerals Calcium is important for mineralization of bone, muscle contraction, and transmission of nervous impulses – Dairy products, dark green vegetables, and some nuts are good sources of Ca2+ (1,000 mg · day) Iron is a critical component of hemoglobin and myoglobin – Men and postmenopausal women should ingest 8 mg of iron each day, premenopausal women should aim to ingest 18 mg Sodium and Potassium are critical electrolytes; potassium also assists with nerve transmission and active transport mechanisms.  Water Absolutely essential for life – Body is 50-75% water Protects key body tissues (spinal cord, brain, organs) Aids in O2, nutrient, hormone and waste transportation Regulates body temperature The AI for men is 3.7 L · day–1 and for women is 2.7 L · day–1  Nutrient Timing What to eat Before, During, and After  Fully Hydrate Before Exercise! Dehydration has negative effects on performance – 1% bodyweight loss can lead to an elevation in core temperature – 3% lowers performance – 3-5% bodyweight loss lowers thermoregulatory capabilities – 7% bodyweight loss, collapse is likely *Athletes commonly lose 2-6% during practices in the heat  Avg. Rates of Fluid Loss Fluid loss during exercise is related to exercise intensity, environmental temperature, and individual sweat characteristics ▪ Sweat rate may reach 3.0 l hˉ¹ (Hermansen 1967)  Hydration Guidelines 350-600 ml of water 2 hr before exercise 200-300 ml 10 to 20 min before exercise 150-350 ml every 15 to 20 min during exercise  Post-Exercise Hydration Strategy Complete restoration of fluid lost during exercise cannot occur without replacement of electrolytes, primarily sodium Electrolyte-containing solution: Sodium 20 to 80 mmol lˉ¹ Potassium 2 to 6 mmol lˉ¹ 475-700 ml of fluid after exercise for every 0.5 kg of weight lost  Fuel utilization during exercise During exercise muscles need CHO and FFA for ATP production Plasma FFA come from adipose tissue Glucose comes predominantly from muscle/liver glycogenolysis  Carbohydrates=Fuel Blood glucose levels and the amount of CHO (i.e., glycogen) stored in the muscles can have a large impact on fatigue rates. Glycogen availability is a primary limiting factor in exercise bouts that last longer than 60 minutes. The initial amount of glycogen stored in the muscle is directly proportional to the athletes ability to sustain exercise for more than a 60 min time period at work rates >70% VO2max.  CHO Pre- and Post-Training 1-4 hours prior to exercise: 1-4g/kg BW CHO Post workout: 1-1.5 g CHO per kg of bodyweight consumed at frequent (every 2 hours) intervals. 7 6 33% - h 5 48% -1, Glycogen Syntehsis (mmol kg. 4 22% 3 2 1 0 CHO IP + 2P CHO 2P No CHO Carbohydrate Treatment Effect of Different Carbohydrate Ingestion Times on Glycogen Resynthesis Rates. Initiating Muscle Protein Synthesis and Limiting Muscle Tissue Damage  Combining CHO+PRO ✓ Roy et al. 1997 ✓ 1 g of CHO per kg of bodyweight significantly elevated the plasma insulin response and increased protein synthesis rates by 36% following endurance exercise. ✓ Significant reduction in urinary nitrogen and 3-mthlyhistiine--> suggesting a reduction in muscle tissue damage and protein breakdown. ✓ Zawadzki et al. ✓ 3:1 carbohydrate/protein supplement at 2 hour intervals increased the rate of glycogen storage by 38% ✓ Ivy et al. ✓ After 4 hours of recovery, muscle glycogen was 54% and 40% greater for the carbohydrate/protein treatment (80 g CHO, 28 g Pro, 6 g fat) when compared with the iso-carbohydrate (80 g CHO, 6 g fat) and isocaloric treatments (108 g CHO, 6 g fat), respectively  Do You Need To Fuel/Hydrate During Exercise? Are you training for >60 minutes? – If the answer is ’yes’, consider supplementation Sodium – Maintains fluid balance and the drive to drink (Wilk 1996) – Rapid absorption of fluid that enters the intestines – Increase glucose absorption – Prevents hyponatremia (Coyle 2004) Carbohydrates – Beneficial for prolonged continuous exercise, as well as team sports – Use a glucose solution ~6-8% CHO – Can help delay fatigue – May not need to ingest CHO until 30-40 minutes into training, unless hot and humid, then 250 ml every 15 mins.  What can result from inadequate nutrition? If energy intake is too low for energy expenditure: Increased risk of injury Decreased immune function Poor bone health Fatigue →impact on training, recovery, performance Affect on growth, delayed puberty (adolescents) Menstrual irregularities