PFit 4/29

Adenosine Triphosphate (ATP)

Energy in food must be converted to this for immediate use by the body

Resting Muscle Cell

Contains just enough ATP to keep the muscle working for 2-4 seconds

Phosphocreatine (PC)

High-energy compound used to create more ATP, used to reform ATP from ADP (Adenosine diphosphate)

Carbohydrates, Proteins, Lipids

Compounds that are broken down, releasing energy to make more ATP

Creatine

Organic Molecule in muscle cells that is a part of the high energy compound phosphocreatine; aids ATP production in muscles

Advantage of PC

Can be activated instantly and replenished quickly

Disadvantage of PC

Too little made and too little stored in muscles

Carbohydrate

major fuel for short term, high-intensity, and medium term exercise

Glycologyen

Storage form of glucose stored in liver and muscles

Muscle Glycogen

Supplies glucose to and fuels the working muscles

Liver Glycogen

Maintains blood glucose levels

Main fuel for exercises under 30 minutes

Primarily use muscle glycogen; hormonal response may be blunted

Activity time increase: Muscle

Muscle glycogen depletes, and muscles begin to use blood glucose, contributing to fatigue

Activity time increase: Liver

Liver glycogen depletion leads to a drop in blood glucose; as glycogen stores are depleted, performance drops and muscles can only work at 50% capacity (hitting the wall)

Carbohydrate Loading

Used for exercise at 70-80% max for 1+ hour; helps delay fatigue and can double typical carb stores

Blood Glucose Maintenance

Used for exercise over 30 minutes to prevent "bonking," an extreme state of fatigue seen through irritability, sweating, anxiety, weakness, headache, or confusion

Carbohydrate Intake

Recommend 0.7g-1g/kg/hour (30-60g/hour) during prolonged exercise (not in notes but g/kg/hour meaning gram of carbohydrates per kilogram of body weight, per hour)

Fat

Main fuel for prolonged, low-intensity exercise; the predominant fuel source at rest that supplies 50-90% of energy at rest

Factors affecting Fat use

Rate at which fatty acids are used is affected by muscles training level, size and number of mitochondria, and muscle myoglobin levels (needed for fat metabolism)

Triglyceridas

Storage form of fat in the body that provides more than twice the energy of carbs, yielding more ATP

Carbohydrate vs Fat Metabolism

Carb metobolism is more efficient; fat needs to burn in a "fire of carbs" (meaning carbs are needed for fat to burn more effectively)

5 Adaptations to Endurance Exercise (skeletal muscle)

Increased ability of muscle to store glycogen, increased triglyceride storage in muscle, increased mitochondrial size and number, increased myoglobin content, increased cardiac output

Increased ability of muscle to store glycogen: Advantage

More glycogen fuel available for the final minutes of an event

Increased triglyceride storage in muscle: Advantage

Conserves glycogen by allowing for increased fat use

Increased mitochondrial size and number: Advantage

Conserves glycogen by allowing for increased fat use

Increased myoglobin content: Advantage

Increased oxygen delivery to muscles and increased ability to use fat for fuel

Increased cardiac output: Advantage

Increased blood flow to promote adequate delivery of oxygen and nutrients to muscles

Protein use in Exercise (minor)

Provides minor fuel when carbs are low, supplies 5% of total energy and up to 15% depending on endurance needs; used least in weight lifting

After Weight Training Recommended Nutrition

High carbohydrates, moderate protein foods; will allow for enhancement of anabolic effect, enhance blood insulin and growth hormone, and support muscle growth

VO2 Max

Fuel sources can be estimated based of percent of this; fat use drops as intensity increases; high intensity = carbohydrates and VERY high intensity = phosphocreatine