Nutrition and Athlete Exam #3

Recommendations to Maximise the Potential for Nitrate Supplementation to Improve Exercise Performance?

as well as 2 beetroot juice shots, an acute dose of 200-300 g of (or a combination of) the following foods will provide > 500-750 mg NO3-: lettuce, spinach, celery, cress, rocket avoid boiling and freezing, make a salad!

Why is caffeine classified as a drug?

because it stimulates the central nervous system

Influence of Dietary Nitrate Supplementation on Plasma Nitrite?

higher mol of nitrate (NO3-) administered leads to higher spike in plasma nitrite 4.2 vs. 8.4 vs. 16.8 mmol

Ergogenic

increases muscular work capacity and overall performance

How long does it take for caffeine to be absorbed by the body?

intestinal tract absorbs caffeine rapidly within 1 hr

High-Intensity Exercise Intramuscular Metabolic Perturbation

lower levels muscle ADP and Pi produced in nitrate group compared to placebo

Influence of Dietary Nitrate Supplementation on Exercise Performance in the Highly Trained/Elite?

mean 0.4% increase in performance over the results of 9 studies

Influence of Dietary Nitrate Supplementation on Cycling Economy?

mean of 10 articles showed 2.5% decrease in end exercise pulmonary oxygen uptake with nitrate supplementation

High energy phosphate metabolism

muscle PCr decreases at a slower rate with nitrate supplementation compared to placebo

Nitric Oxide

neurotransmission Ca2+ handling glucose uptake vasodilation mitochondrial respiration muscle force production

Mitochondria P/O (phosphate/oxygen) Ratio

refers to the amount of ATP produced from the movement of two electrons through a defined electron transport chain, donated by reduction of an oxygen atom ratio increased in nitrate group compared to placebo group

Glucuronolactone

"Increases feelings of well-being" A normal, human metabolite formed from glucose (sugar produced by the metabolism of glucose in the human liver) When glucuronolactone is taken orally, it is rapidly absorbed, metabolized, and excreted 600mg/can, normal human intake 250mg/day just another added source of sugar, which adds calories to the beverage and has the potential to add inches to your waistline

Caffeine

-naturally occurring substance. It is part of a group of chemical compounds called methylxanthines -chemical name is 1,3,7-trimethylxanthine -natural chemical found in tea leaves, coffee beans, cocoa beans and kola nuts (63 plant species contain it in their leaves fruits or seeds) --> These are used to make coffee, tea, energy drinks, soft drinks, chocolates, and medicines -its a stimulant, meaning it makes us feel more alert and awake after drinking or eating foods or beverages that contain it -can be addictive

Proposed mechanism for ergogenic action of caffeine?

1) directly on adipose and peripheral vascular tissues 2) indirectly from caffeine's stimulating epinephrine release from the adrenal medulla; epinephrine then acts as an antagonist of the adenosine receptors on adipocyte cells (adenosine receptors repress lipolysis) It then activates hormone-sensitive lipases to promote lipolysis and releases free fatty acids into the plasma

Sources of dietary nitrate?

60 - 80% of nitrate consumption through the diet is in the form of vegetables highest amount in celery, lettuce, spinach, red beetroot lowest amount in artichokes, asparagus, eggplant, onion, squash, sweet potato

how much caffeine is in a cup of coffee?

60 to 150mg for brewed coffee 100mg for instant coffee 20-50mg for brewed tea 50mg for soft drinks 250-400mg for percolated coffee

What percentages of caffeine intake come from coffee and tea?

75% coffee (14 million kg) 25% tea

Guarana

A shrub that grows in South America Similar to caffeine, guarana is an herbal stimulant from South America While the labels tell you exactly how much caffeine is in the drink, but don't tell how much caffeine one gets from the guarana Extracts of the plant, fruit, or seed A stimulant and flavoring 1 gram of guarana contains about 40 mg of caffeine

Low-Intensity Exercise Muscle ATP Turnover Rates

ATP turnover reduced in nitrate groups compared to placebo in ATPtotal, ATPox, ATPpcr, ATPgly

How does caffeine work?

Absorbed in the stomach and the intestine (peak blood levels occur about 45 - 60 minutes after ingestion) Stimulates brain activity Physiologic effects: -Increase blood pressure -Increase pulse -Increase stomach acid production -Fat stores break down -Fatty acids released intoblood stream Effects can last from a few hours to as long as 12

B-Group Vitamins

B-vitamins include: Thiamine (B1) Riboflavin (B2) Niacin (B3) Pyrodoxine (B6) Claims to burn fat Excess B-vitamins are excreted in urine (well balanced diet provides enough of these vitamins)

Influence of Dietary Nitrate Supplementation on Exercise Tolerance?

Bailey et al: Time to exhaustion longer in nitrate group compared to placebo (16% higher) Wylie et al: Acute supplementation with 70, 140 and 280 ml beetroot juice containing 4.2, 8.4 and 16.8 mmol NO3-, respectively Time to task failure longest in 8.4 mol group (14% greater than placebo) vs 16.8 mol (12% greater than placebo) Running/Knee extension: Exercise tolerance is improved during high-intensity constant work rate by ~10-20% This would be predicted to translate into a 1-2% improvement in exercise performance -A 1-2% faster completion time over a set distance

Taurine

Believed to enhance the effects of caffeine Involved in a number of physiological processes including neuronal excitability In the body, taurine works in the digestion of fat Energy drinks contain up to 10 times the usual intake from diet

What factors influence caffeine sensitivity?

Body Mass: person with a smaller body mass will feel the effects of caffeine sooner than those with larger body masses History of caffeine use: people who don't regularly consume caffeine tend to be more susceptible to its negative effects than are people who do Stress: all types of stress (psychological, heat, etc.) can increase a person's sensitivity to caffeine Age, smoking habits, drug or hormone use, and health conditions like anxiety disorders may influence caffeine sensitivity

Is caffeine ergogenic?

Caffeine can be ergogenic at a variety of doses As little as 1.2 mg of caffeine per kilogram and upwards of 6mg caffeine per kilogram of bodyweight has been shown to increase endurance. Caffeine may increase endurance time at low to moderate dose Individual variation, try in training first

Caffeine effects on muscle?

Caffeine may act directly on muscle to enhance its capacity for exercise It exerts a direct and specific ergogenic effect on skeletal muscle during repetitive low-frequency stimulation It increases the sarcoplasmic reticulum's permeability to calcium ions and influences the myofibril's sensitivity to calcium ions to augment excitation-contraction coupling

How does caffeine affect the CNS?

Caffeine produces analgesic effects on the central nervous system and enhances motor neuronal excitability. It also exerts a calming effect on neurons of the brain and spinal cord

Energy drinks

Canned or bottled carbonated beverages with high amounts of sugar, caffeine, herbal stimulants and supplements (B vitamins, amino acids (taurine), and herbal stimulants such as guarana) Marketed with claims of: Increased endurance Strength and power Weight loss Feelings of euphoria

Do you know what you are drinking in energy drinks?

Creatine may cause muscle cramps, weight gain, and increased body mass Inositol claims to decrease fat and cholesterol levels and lower the risk of cardiovascular disease Bitter Orange may be harmful weight-loss supplement. Chemicals found in bitter orange may cause high blood pressure (hypertension) and irregular heart beat (arrhythmias), which can lead to heart attack, stroke or even death

What are the ergogenic effects of caffeine?

Electrolyte balance and glucose availability are key factors that influence caffeine's ergogenic effect An ergogenic effect occurs with caffeine ingestion PRIOR to exercising Consuming caffeine before exercise increased fat catabolism and reduced carbohydrate oxidation based on plasma glycerol and free fatty acid levels

Regulation of energy drinks?

Energy drinks are currently unregulated in theUnited States FDA requires beverage manufacturers to list the presence of caffeine on the label, but not the amount of caffeine in the product Herbs and supplements added to energy drinks are not strictly regulated by the FDA There is a no guarantee of strength, purity, or safety of the herbs and supplements that are added to energy drinks

Muscle blood flow distribution?

Ferguson et al: Hindlimb blood flow was increased during exercise in rats fed with beetroot juice for 5 days Blood flow was preferentially distributed towards type II muscle fibers

What are the side effects of too much caffeine? (500 mg or more)

Insomnia Restlessness Increased heart rate Increased blood pressure Abnormal heart rhythm Anxiety/nervousness Irritability

Nitrate-Nitrite-Nitric Oxide Pathway

NO3- nitrate NO2- nitrite NO nitric oxide NO3- in food --> NO2- stomach back to mouth bacterial anaerobes so avoid mouthwash NO2- --> NO in stomach hypoxia/acidosis

Influence of Dietary Nitrate Supplementation on Exercise Performance?

Nitrate supplementation appears to be ergogenic for: -Exercise tolerance -Endurance exercise performance -Intermittent exercise performance Wilkerson et al 24% ↑ plasma [nitrite] above baseline with BR ingestion Time taken to complete 50 mile TT was negatively correlated to change in plasma [nitrite] with BR ingestion Bescos et al: Positive correlations between the ↑ plasma [nitrate] with nitrate supplementation and the increase in distance (r = 0.53), speed (r = 0.52) and power (r = 0.54) in the 40 min distance trial

When did energy drinks first appear on the market?

Originated in Asia and Europe in the 1960s First appeared in the U.S. in the 1980s with Jolt Cola: high sugar, high caffeine soda with the slogan "twice the sugar and caffeine of regular soda." (marketed as a caffeinated drink and not an energy drink) The first drink marketed as an energy drink in the U.S. was Red Bull which is based on a drink from Thailand and is produced in Austria

Caffeine warnings?

People who don't usually consume caffeine may experience undesirable side effects Caffeine stimulates the central nervous system and causes headache, nervous irritability, insomnia, tremulousness, muscle twitching, elevated heart rate and blood pressure, and trigger premature left ventricular contractions

How doe food preparation affect nitrate levels?

Plants store nitrate in vacuoles Boiling vegetables causes the release of stored nitrate into the surrounding fluid This can reduce the nitrate content of vegetables by up to 50%! Freezing vegetables can also reduce the nitrate content It has been estimated that ~ 20-25% of the nitrate content of vegetables is lost as a result of freezing!

Common misconception between energy and sports drinks?

Sports drinks and energy drinks are NOT the same (even though energy drink companies sponsor many sporting events) Energy Drinks: Caffeine filled High concentration of sugar Contain herbal stimulants Sports Drinks: Fluid balance Electrolyte concentration Provide energy Isotonic

Caffeine and long-term health effects?

Studies have found no substantial evidence linking caffeine to these conditions: Blood Pressure Cardiac Arrhythmias Pregnancy Osteoporosis Cancer There may be a temporary rise on blood pressure due to caffeine consumption but typically only lasts as long as the effects of caffeine - a few hours

Mechanisms for the Improved Exercise Economy with Nitrate?

To reduce the O2 cost of exercise at the same WR, dietary nitrate supplementation may have: True: 1) Increased the mitochondrial P/O ratio (i.e., reduced the O2 cost of ATP resynthesis) False: 2) Inhibited mitochondrial ATP synthesis- resulting in a compensatory increase in anaerobic energy liberation True: 3) Reduced the ATP cost of force production Dietary nitrate reduced the O2 cost of low- and high-intensity exercise at the same WR