NS1220 - Sports Nutrition

Two Major Forms of Exercise

are aerobic exercise and anaerobic exercise, which serve different physiological purposes and energy requirements in the body.

Aerobic Exercise

Also known as endurance exercise. It is any sustained physical activity that increases heart rate and breathing, utilizing oxygen for energy production. Takes time for aerobic to start

Examples of aerobic exercise

include running, swimming, cycling, and dancing.

Anaerobic Exercise

Also known as resistance exercise. It is a type of high-intensity exercise that relies on energy sources stored in the muscles, producing energy without the use of oxygen.

Instant Energy

Stored ATP and creatine phosphate. Occurs for 10-15 seconds of exercise

Short-term energy

Anaerobic metabolism of glucose; occurs after 15 seconds to 2-3 mins of exercise

Long-Term exercise

aerobic metabolism uses glucose and fatty acids (some protein), with relative contribution depending on intensity (anaerobic metabolism continues to contribute at higher intensities); occurs 2-3 mins of exercise and beyond

Main fuels for exercising muscles

are carbohydrates and fats, with proteins playing a minor role. These fuels are utilized based on exercise intensity and duration.

Fat as Fuel

Fat is utilized by the body during prolonged exercise, especially when glycogen stores are depleted.

Fat as Fuel: Advantages

include a high energy yield, sparing glycogen, and supporting endurance performance. Huge resources (>100,000 kcal)

Fat as Fuel: Disadvantage

includes slower energy release, reduced intensity output, and potential gastrointestinal discomfort during digestion.

Carbs as Fuel

Carbohydrates are the body's preferred source of energy during high-intensity exercise, providing quick energy through glycogen stores.

Carbs as Fuel: Advantage

include rapid energy availability, enhanced performance in high-intensity activities, and improved recovery post-exercise; locally available

Carbs as Fuel: Disadvantages

may include gastrointestinal distress, risk of insulin spikes, limited storage (~2000 kcals) and inadequate energy for prolonged low-intensity activities.

What happens when muscle glycogen stores are depleted during competition?

Muscle fatigue, decreased performance, and reliance on fat as an energy source, which is less efficient.

How to measure maximal aerobic power/capacity?

Maximal aerobic power, or VO2 max, can be measured through progressive exercise testing until exhaustion, typically conducted on a treadmill or cycle ergometer, measuring oxygen consumption.

What is the advantage of obtaining a larger % of the energy from fat?

It allows for better endurance and performance during prolonged activities, reduces reliance on glycogen stores, and can improve fat oxidation efficiency.

How to measure maximal anaerobic power/capacity?

Maximal anaerobic power can be measured through short-duration, high-intensity exercise tests like the Wingate test, assessing peak power output and anaerobic capacity. Also, one rep max can help determine it.

What types of athletic performances benefit the most from proper nutrition?

Endurance events, strength training, and high-intensity sports all significantly improve with proper nutrition, enhancing energy availability, recovery, and overall performance.

Performance

Nutrition is just one part of performance; other factors include training, mental preparation, and recovery strategies. It’s about optimizing genetics

General Dietary Guidelines for Sports Nutrition

• provide enough energy and nutrients to meet the demands of training and exercise

• optimize adaptation and recovery (eating well afterwards) between training sessions

• enable the athlete to achieve optimal body weight, muscle mass, and body fat levels for performance

• provide adequate fluids to ensure maximum hydration

• promote the short and long-term health of athletes

  Athletes’ diet similar to the recommended for the general public, with some exceptions

What is the most important macronutrient before and during an endurance competition?

Carbohydrates are the most important macronutrient before and during an endurance competition, as they provide the primary source of energy for athletes.

What is the major fuel during endurance competition?

Fats are the major fuel during endurance competitions, providing a sustained energy source when carbohydrates are depleted.

Glycogen in liver and muscle

is the stored form of carbohydrates that provides energy during physical activity. It is crucial for maintaining blood glucose levels and fueling muscle contractions.

Exercise with Full Glycogen Stores

refers to having optimal levels of glycogen stored in muscles and the liver, which enhances performance and endurance during exercise by providing readily available energy.

Exercise with Low Glycogen Levels

occurs when glycogen stores are depleted, leading to fatigue and reduced performance during physical activities. This can impair endurance and increase the risk of injury.

Can muscle glycogen be fully restored in one day?

Yes, muscle glycogen can often be fully restored within 24 hours after intense exercise, provided that adequate carbohydrate intake and recovery strategies are employed.

What is the major fuel during anaerobic competition?

Protein

What is the major fuel before anaerobic competition?

Carbohydrates

Role of protein

In sports nutrition, protein plays a crucial role in muscle repair, recovery, and growth, especially after intense exercise. It also supports overall bodily functions and can serve as a supplementary energy source when carbohydrates are not sufficient.

Summary Recommendations from the International Society of Sports Nutrition

• For building muscle mass, an overall daily protein intake in the range of 1.4-20.g/kg body weight/day is sufficient

• Higher protein intakes (2.3-3.1g/kg/d( may be needed to maximize the retention of lean body mass in resistance-trained subjects during hypocaloric periods

• Single protein doses should strive to contain 200-3000 mg of leucine and a balanced array of essential amino acids

• Supplementation is a practical way of ensuring intake of adequate protein quality and quantity while minimizing caloric intake

What is the major source of energy during a running marathon?

stored fat

Condition muscles rely less on _____ and more on ______ for energy

fat, glycogen

Which of the following statements about fuel use during exercise is false?
a) Muscles glycogen can only be used by the muscle in which it is stored

b) Trained athletes are more effective at mobilizing stored fat during exercise

c) The use of glucose as fuel provides more power (energy consumed/unit of time) than the use of fat

d) Blood glucose cannot be used as an energy source by muscles during exercise

d) Blood glucose cannot be used as an energy source by muscles during exercise

Dehydration

the condition that occurs when the body loses more fluids than it takes in, leading to an electrolyte imbalance and reduced physical performance.

8%+ body weight water loss

detrimental to health

Osmolarity

the measure of solute concentration in a solution, which can affect fluid balance and physiological functions in the body.

Osmolarity of blood

280-290 mmol/L

Fluid replenishment the fastest with slightly hypotonic solution

200-250 mmol/L

Osmolarity of Gatorade

220-300 mmol/L

Hyponatremia

(Water Intoxication) A condition characterized by low sodium concentration in the blood, usually due to excessive fluid intake or loss of sodium; often in combination with use of NSAIDs. Hyponatremia can lead to symptoms such as headache, nausea, and confusion.

Ergogenic aids

Supplements used to enhance recovery, improve strength, speed, or endurance, and enhance the performance of athletes

Ergogenic aids: Effective and Not Dangerous

Sports Drinks, Creatine

Ergogenic aids: Not-effective and not dangerous

Vitamins, chromium, and green tea

Ergogenic aids: Not-effective and dangerous

beta-blocker for endurance sports

Ergogenic aids: Effective and dangerous

steroids, amphetamines, EPO

EPO

A hormone that stimulates red blood cell production, often misused in sports for improving endurance performance.

Ergogenic aids: Metabolic fuels

Legal: Carbohydrate, lactate

Ergogenic aids: components that improve metabolism

Legal: Creatine, caffeine, carnitine, vitamins

Illegal: EPO

Ergogenic aids: Stimulants

Legal: Caffeine, synephrine, theobromine
Illegal: Amphetamines, cocaine

Ergogenic aids: Anabolic substances that enhance performance (also increases muscle mass)

Legal: Protein, amino acids, chromium

Illegal: steroids, growth hormone, insulin clenbuterol

Ergogenic aids: Substances that enhance performance

Legal: fluids, electrolytes

Illegal: steroids

Pre-workout

A supplement that typically contains a blend of ingredients such as caffeine, amino acids, and other compounds intended to boost energy, focus, and endurance during workouts.

Caffeine

A stimulant that enhances alertness and reduces the perception of effort during exercise. It promotes the use of fat as fuel. Accepted best practice does is 3 to 6 mg/kg

Beta-Alanine

An amino acid that helps increase endurance by reducing muscle fatigue and acidosis during high-intensity exercise by making carnosine. It is endogenously produced by the body. Meat, poultry, and fish are good dietary sources.

Creatine

Not helpful in endurance sports, but is helpful for resistance sports. A compound that helps improve strength and muscle mass by replenishing ATP levels during short bursts of high-intensity activity. It is found in higher quantities in meat and fish and can also be taken as a supplement.

Bicarbonate

A substance that can enhance performance by buffering lactic acid accumulation in muscles during high-intensity exercise, delaying fatigue. It is often consumed through sodium bicarbonate. Only advantageous in high-intensity sports, but can cause gastrointestinal distress

Carnitine

No benefit of carnitine ingestion. A nutrient and dietary supplement that plays a crucial role in energy metabolism by transporting fatty acids into the mitochondria for oxidation needed for burning fat. It is found in red meat and dairy products and is often marketed for weight loss and athletic performance. Endogenously produced by the body. Red meat and other products of animal origin are good external sources.

You are a professional cyclist competing in the Tour de France. Would you take the following?

• carnitine

• energy gels

• caffeine

• fluid/electrolyte replacement

• creatine

• beta-alanine

• whey powder

• energy gels

• caffeine

• fluid/electrolyte replacement

Which of the following statements about fluid replacement is correct?
a) Of all beverages, intake of distilled water replenishes lost water in the body
b) Trained athletes are more effective at absorbing water than untrained individuals
c) Post-exercise, alcoholic beverages aid in rehydration
d) Slightly hypotonic drinks result in the most rapid fluid absorption

d) Slightly hypotonic drinks result in the most rapid fluid absorption

Which of the following effects cannot be attributed to caffeine?
a) Reduction in perceived exertion and increase in motor unit recruitment
b) promotes use of fat as fuel
c) Increases alertness and heart rate
d) Promotes muscle mass

d) Promotes muscle mass