Energy Systems

Metabolism

• All chemical reactions that take place in an organism

  • Metabolic reactions do 2 things

    • Extract enrgy from nutrient biomolecules

    • Synthesize or break down molecules

• Metabolism

  • Usefulness of metabolic pathways as supplilers of energy is measured in terms of the new amount of ATP the pathways can yield

    • Aerobic metabolism

      • One glucose molecule yields 30-32 ATP

      • Process requires the presence of oxygen

    • Anaerobic Metabolism

      • Once glucose molecule yields 2 ATP

      • Process doesn't require the presence of oxygen

Energy

• The capacity or ability to perform work

  • All living organisms obtain, store and use energy to fuel their activities

Power

• The rate of change of energy, or how quickly you can perform work

  • Power output is the rate at which working muscles can produce energy

Adenosine triphosphate (ATP)

• 3 phophate groups

• Attached to adenosine

• Immediate energy source for muscle contractions

• The phosphate bonds release energy when they are broken

• ATP is broken down into ADP and a phosphate group and then resynthesize

  • Take energy to resynthesize ATP

Aerobic metabolism

A metabolic process that yields 36 ATP per 2 glucose molecule and requires oxygen.

Anaerobic metabolism

A metabolic process that yields 2 ATP per glucose molecule and does not require oxygen.

Phosphagen system

1. ATP-Creatine-Phosphate System (ATP-PC-System)

2. The immediate energy system

3. Imperative for activities with high power outputs

4. ATP is broken down into Adenosine Diphosphate and inorganic phosphate (ADP and Phosphate) and releases energy. Uses ATPase an enzyme

5. ATP is being resynthesized by the energy released when the chemical bonds of creatine-phosphate are broken. Uses Creatine kinase as enzyme

6. Coupled reaction

Coupled reaction

A process where the energy released by one chemical reaction drives another chemical reaction. Energy released by creatine and phosphate’s bond breaking is used to reform ATP from ADP and P

Anaerobic Glycolysis

1. Anaerobic Glycolysis (no oxygen)

   1. Requires the chemical breakdown of glycogen or glucose

   2. Availability of glucose occurs through 2 methods

      1. Glucose can pass from blood through muscle cell membrane into the cell, Net of 2 ATP

      2. Glucose sprints from stored glycogen in the muscle cell itself, Net of 3 ATP

   1. Will produce Lactate (not lactic acid)

2. It processes ATP quickly during exercise when oxygen demand is greater than supply

3. High rates of ATP production by glycolysis can't be sustained for long

   • 60-90 seconds

4. Local muscle fatigue is typically the result of exhausting this path way

   • Low muscle pH is associated with hydrogen concentration and lactate formation

   • High acidity is believed to contribute to the acute muscular discomfort experienced during intense exercise (local muscle fatigue)

5. Lactate gets resynthesized into glucose again in the liver

Oxidative system

1. Requires the presence of oxygen

2. Predominantly used in everyday activities where intensity is lower and longer in duration, more than 2-3 minutes

3. Chemical breakdown of carbs, fatrs and proteins

   1. Carbohydrate

      1. 4kcal/g

   2. Fat

      1. 9kcal/g

   3. Protein

      1. 4kcal/g

EPOC, Excessive post-exercise comsumption

Uptake of oxygen after exercise that is higher than during typical resting states

• Muscle phosphagen stores (ATP and CP) are replenishing and the oxygen that is carried in blood and muscle

  • Rapid recovery phase

• Body temp can remain elevated for a long time after the cessation of strenuous exercise

  • This increases the rate of chemical reactions in the cells of the body

  • Slower recovery phase

• Residual effects or hormones released during exercise like epinephrine and thyronine and will continue to increase metabolism during recovery until they dissipate

• Energy is needed for tissue repair and redistribution of ions (sodium, potassium, calcium) in the body

• Since heart rate and breathing rate remain elevated during recovery, the extra oxygen is needed for the heart and respiratory muscles

Active vs Passive Recovery

• The return of muscle acidity to normal levels is accelerated by active aerobic recovery exercise

• Active recover speeds up the rate of blood flow throughout the muscle, normalizing muscle acidity faster

Fatigue and Exercise

• Inability to maintain your desired exercise intensity

• Training above LT1

  • Fatigue is likely cause of the depletion of msucle glycogen

• Train close to L2

  • Fatigue is likely due to the inability to continue to buffer high muscle acidity at the required rate

    • Not able to control muscle acidity

• Training above LT2

  • Fatigue occur quickly cause of high muscle acidity, reducing ATP production through glycolysis

Lactate

A by-product of anaerobic metabolism often viewed as a source of fuel and does not directly cause fatigue.

Central Nervous System (CNS) fatigue

• During intense repeated bout of strenuous exercise neurotransmitters get deplete and reduces physically and cognitive performance

• Muscular fatigue from the CNS results in a reduction in the neural drive to working muscles

  • Will decrease in force output

• Peripheral weakness manifests as a local, muscle-specific incapacity to do work

Peak Power with Phosphagen System

• Peak power

  • Used in activates that only take a few seconds or less

  • 10 seconds or less, primarily relies on stored  ATP

  • 1 max jump

• Sustained power

  • Used in activities that required high power outputs for several seconds

  • Primarily relies on ATP-CP system

  • Long jump, 60-100m sprint

Glycolytic System Breakdown

Glucose turns into 2 pyruvate than into 2 lactate. The lactate is then resynthesized into glucose in the liver

Oxidative System Breakdown

Glucose turns into pyruvate and then into Acetyl Co-A as it enters the mitochondria. The citric Acid Cycle occurs in the mitochondria and CO2 are produced. Hydrogen ions and high energy electrons are removed from carbon atoms and move into the electron transport system. They combine with oxygen to form water and ATP.

This creates a total of 38 ATP, 2 ATP from turning into pyruvate and 36 after the electron transport system

Oxidation of Fats

• Aerobic lipolysis

• Fatty acids are released from adipose tissue and used to make ATP

• Fat is the ideal way for our bodies to story energy since its so energy dense. 1g of fat if 9kcal

• occurs when we exercise for incredibly long periods of time like 3-4 hours

Oxidation of Fat Breakdown

Fat to fatty acids than goes through beta oxidation to turn into acetyl Co-A. This then goes into the citric Acid cycle, a hydrogen ion and high energy electron enters the electron transport system to turn into O2 and ATP

Protein Metabolism

• Least preferred energy source

• Additional by-products of urea and ammonia

• We would rather use protein to repair muscle than as an energy source

Aerobic breakdown of protein

Proteins turns into amino acids and gets deaminated. Then entres the citric acid cycle, then the electron transport system and gets turned into H2O and ATP

Recovery Time

• The time to recover from exercise varies

• For steady-state aerobic exercises (less than 50-60% of VO2 max for non endurance athletes) or maximum-intensity work for 10-15s (ATP-CP), very little muscle aciditly and lactate accumulates

  • Recovery is rapid

• If body temp is not significantly elevated the EPOC will not be large

• Glycogen fuel may be depleted by only significantly in extended endurance like half-marathons and above

Recommened Recovery Times to Replenish Fuel

• Restoration of ATP and CP

  • 2-3 mins

• EPOC (Rapid Phase)

  • 3-5 mins

• EPOC (Slow Phase)

  • 30mins - 1 hour

• Removal of lactate from muscle and bloow during exercise-recovery

  • 30min - 1 hour

• Removal of lactate from muscles and blood during rest-recovery

  • 1-2 hours

• Restoration of muscle glycogen after a long intermittent exercise like a soccer game

  • 5-24 hours

• Restoration of muscle glycogen after a prolong exercise like a marathon

  • 10-46 hours

Percentage of Use of the 3 energy systems

• Very short and very High intensity will use the ATP-CP systems

• Short and High Intensity will use the anaerobic glycolysis system

• Medium length and moderate intensity will use aerobic glycolysis system

• Long and lighter intensity will use the aerobic lipolysis

Oxygen Consumption during exercise

• there is an oxygen deficit during exercise at the start of exercise

• that why we warm up so that by game time our bodies won’t be oxygen deprived

• when in oxygen deficit we must use our anaerobic system