Macronutrients, Metabolism and ATP

• Macronutrients include carbohydrates, proteins, and fats
• Carbohydrates have a caloric value of 4.1
• Proteins have a caloric value of 4.3
• Fats have a caloric value of 9.3

Carbohydrates

• Formed by green plants from CO2 and water during photosynthesis
• Carbon dioxide from the air combines with water in the presence of sunlight to produce carbohydrates
• Oxygen is released as a byproduct
• Humans reverse this process to extract energy and release carbon dioxide

Glycogen

• Glucose is the form that carbohydrates are usually assimilated by humans
• Stored as glycogen within skeletal muscle and the liver
• Stored glucose can be broken down for energy during stress or muscular activity

Metabolism

• Complex process that supplies energy throughout the body
• It is how energy-rich material is assimilated by the body for energy renewal

ATP - Adenosine Triphosphate

• Energy is stored between phosphates in the ATP molecule
• The chemical formula for releasing energy from ATP is ADP + P + energy
• The body must make ATP because it ensures bodily functions and physical movements

Aerobic vs Anaerobic Systems

• Aerobic system uses oxygen, anaerobic system does not
• Aerobic involves enzymes and complex pathways
• Anaerobic involves chemicals and enzymes

Metabolic Pathways

• ATP-PC pathway is anaerobic alactic
• Glycolysis pathway is anaerobic lactic
• Cellular respiration is aerobic

Pathway Characteristics

• ATP-PC system is also called the phosphagen system or anaerobic alactic
• Glycolysis pathway is anaerobic lactic
• Cellular respiration is aerobic
• Oxygen is not required for ATP-PC, or for Glycolysis but needed for cellular respiration
• Lactate is only produced in the Glycolysis pathway
• Phosphocreatine is the energy source for ATP-PC
• Glucose is the energy source for Glycolysis
• Chemical reaction for ATP-PC is PC + ADP -> ATP + creatine
• Chemical reaction for Glycolysis is C6H12O6 (Glucose) + 2A
• Chemical reaction for cellular respiration is C6H2O6+6O+36ADP+36
• Formula for ATP-PC is DP + 2P -> 2C3H6O3(Lactate) + 2ATP + 2H2O
• Formula for cellular respiration is P -> 6CO2 + 36 ATP + 6H2O
• ATP-PC lasts 10-15 seconds with 2-5 minutes recovery time
• ATP Yield is higher in cellular respiration than glycolysis

Glycolysis

• If sufficient oxygen is present at the end of glycolysis, pyruvate enters
• If insufficient oxygen is present, pyruvate is transformed

Cellular Respiration Sub-Pathways

• Glycolysis produces lactic acid
• Blood lactate threshold is defined
• Anaerobic threshold is defined
• EPOC training is required to increase the threshold

Cori Cycle

• Pyruvate turns into lactate if you stop exercising
• Lactate then goes through the liver and turns into glycogen

Fats

• Fats are an ideal fuel source because they contain large quantities of stored energy
• Adipose tissue and muscle cells store fatty acids
• The body stores fats as triglycerides
• Fatty acids enter the energy system at lipolysis
• Fatty acids are converted to Acetyl CoA through Beta Oxidation in the mitochondria
• Beta Oxidation involves four chemical reactions

Protein

• Protein yields about as much energy as carbohydrates
• Protein is part of body tissue or component of the metabolic system
• Protein is composed of about 20 amino acids, nine of which must be consumed from food
• As an energy source, protein must be broken down into separate amino acids
• Protein plays a role in Endurance type activities or during chronic periods of glycogen

Protein Supplementation

• When supplementing with protein, consume more than the recommended dietary allowence
• RDA for males is 55-60g
• RDA for females is 42-45g
• Protein (amino acids) composes structural body parts especially muscles
• If you consume more protein your muscles will get bigger and stronger

Myoglobin

• Myoglobin is an oxygen storage unit delivering oxygen to working muscles
• It enables energy producing biochemical reactions

Muscle Fiber Types

• Slow twitch muscle fibers have high levels of myoglobin
• Are red in color
• Cycle slowly
• Have low myosin ATPase
• Low glycolytic enzymes
• High oxidative enzymes and are used for endurance activities
• Fast twitch muslce fibers have low levels of myoglobin
• Are pale whitish
• Cycle quickly
• Have high myosin ATPase
• High glycolytic enzymes
• Low oxidative enzymes and are used for sprints and power activities

Fibre Types

• Type I is slow oxidative (SO)
• Type IIA is Fast oxidative glycolysis (FOG)
• Type IIB is Fast glycolysis (FG)
• Type I is red, small, slow and high in energy efficiency, force production, myoglobin content, myosin ATPase, fatigue resistance and aerobic capacity, and low in anaerobic capacity
• Type IIA is red/white, medium, fast with low energy efficiency, intermediate in force production and moderate in myoglobin content, myosin ATPase, fatigue resistance and aerobic capacity, and high in anaerobic capacity
• Type IIB is white, large, very fast with low force production and energy efficiency, low myoglobin content, high myosin ATPase, fatigue resistance and aerobic/anaerobic capacity
• Research shows Type IIB fibres can become type IIA fibre through aerobic endurance training
• Type IIA cannot transition to type I or IIB

Tonic Muscles

• Assist the body with maintaining posture or stability during activities like standing, walking, and throwing
• Characterized by a high percentage of Type I fibre
• Have slow-twitch fibres with little ability to function explosively, but with considerable endurance capacity
• The soleus muscle is an example

Phasic Muscles

• Characterized by a higher percentage of Type IIA and Type IIB fibres
• The biceps is an example
• Have a lower percentage of Type I fibres
• The only way to know what percentage of muscle fibre types are found in either tonic of phasic muscles is to conduct a biopsy

Endurance

• Endurance athletes have 70-80% slow twitch fibers
• They emphasize fatigue resistance
• Training focuses on improving the oxygen-processing capacity of lungs and blood
• Training increases mitochondria, myoglobin and enzymes involved in C.R.

Sprinters

• Sprinters have 70-80% fast twitch fibers
• They emphasize rapid bursts of energy
• Short powerful training sessions will increase PC
• Intense exercise (90 secs) will increase glycogen stores, and ability of acting enzymes
• It will also delay the point at which lactic acid builds up

Energy System Overview

• Cellular respiration is aerobic
• Glycolysis is aerobic
• ATP-PC is Anaerobic
• Type I slow oxidative (SO) fibres are energy source for cellular respiration
• Type IIA Fast oxidative glycolysis (FOG) fires are energy source glycolysis
• Type IIB Fast glycolysis (FG) fibres are energy source for ATP-PC

Review Questions

• Blood spikes are what define blood lactate threshold
• Glycolysis in Kreb Cycle produces lactic acid
• Cori cycle is how the body decreases lactic acid levels
• Cori cycle converts lactate into glucose