P.E U3AOS2 - Energy systems

why do we need energy

• Energy is needed for muscular contractions; this comes from a compound called Adenosine Triphosphate (ATP).

• To keep exercising and contracting muscles we must re-synthesize ATP, via our energy systems.

3 energy systems

• ATP-PC

• Anaerobic glycolysis

• Aerobic

ATP-PC (fuel, intensity, duration, rate, yield, sport examples, replenishment)

(without O2)

• Chemical fuel = PC

• Intensity = Maximal, 95+ HR Max, 10 RPE

• Duration = Until PC depletes (it won’t fully deplete to 0, and time is different for all athletes)

• Rate = Very fast

• Yield = Very low

• Sport examples = 20 m sprint, shotput, discuss, high jump

• Replenish = via passive recovery

  70 % in 30 seconds

  98% in 2-3 minutes

anaerobic glycolysis (fuel, intensity, duration, rate, yield, sport examples, products, replenishment)

(without O2)

• Chemical fuel = Glycogen

• Food fuel = Carbohydrates

• Intensity = High, 85 - 95% HR Max

• Duration = As PC depletes and until o2 reaches muscles at sufficient levels.

• Rate = Fast

• Yield = Low

• Sport examples = 200m sprint, 400 m sprint, 100 m swim

• Products = hydrogen ions (which are fatiguing bi-products that can inhibit and slow muscle contractions)

• Replenish = via active recovery

  
  

aerobic (fuel, intensity, duration, rate, yield, sport examples, replenishment)

(with O2)

• Food fuel = Carbs and Fats

• Intensity = Low, less than 85% HR Max

• Duration = once O2 has reached the muscles and there are sufficient levels (long duration)

• Rate = Very slow

• Yield = Very high

• Sport examples = Marathon, triathlon, cross country skiing

• Replenish = via active recovery

stockers rule

once the aerobic energy systems has become the greatest contributor, it stays that way with increasing contribution for higher intensity movements.

pros and cons of ATP-PC

• pros =

  Fast rate

  Can replenish quickly

• cons =

  Low yield and therefore PC runs out quickly

pros and cons of anaerobic glycolysis

• pros =

  Faster rate then Aerobic

  Higher yield than ATP-PC

• cons =

  Not as fast a rate as ATP-PC

  H+ ions accumulate (slow contractions)

  Longer to get back to pre-exercise levels

pros and cons of aerobic

• pros =

  high yield

  no fatiguing biproducts

• cons =

  Slow rate

fuels

PC, carbohydrates (CHO), fats, protein

systems and their fuels

ATP-PC = PC

ANEROBIC GLYCOLYSIS = carbohydrates

AEROBIC = carbohydrates, fats and protein

what are carbs and fats broken down & stored as

carbs broken down into glucose and stored as glycogen.

fats are broken down into amino acids and stored as adipose tissue

when CP is used and how much is stored/broken down

The most important fuel when undertaking max-effort exercise lasting a few seconds.

Stored in small amounts in skeletal muscle and does not require oxygen (anaerobic) to be broken down.

when CHO is used and how it is stored/broken down

Dominate in exercise that has a 65%+ VO2 Max OR 70-75% HR max (less = fats)

Can be broken down with or without oxygen (that is, aerobically or anaerobically)

Stored in limited quantities (90-120 min) in skeletal muscle and liver tissue as glycogen

when fats are used and how they are stored/broken down

are an important fuel for sub-maximal exercise that lasts several hours.

Is broken down using large amounts of oxygen and is a more complex molecule meaning it is more complex and takes longer to break down.

when is protein used

Only used for ATP production during times of extreme famine!

the crossover concept

• shows the relative contributions of CHO and fat as fuel for exercise of increasing intensity. 

• As intensity increases, the contribution of CHO will increase and the utilization of fat will decline.

define O2 deficit, steady state and EPOC

• O2 deficit - oxygen supply is LESS than demand

• Steady state - when oxygen supply is EQUAL to demand

• EPOC - when oxygen supply is GREATER than demand

EPOC / When to use passive and active recovery and what active recovery does

• Passive recovery (less than 20 seconds)

• Active Recovery (more than 20 seconds)

  Active recovery allows:

  • Oxidise H+ ions & get back to pre-exercise levels QUICKER!

  • Increase venous return & myoglobin saturation

  • Prevent venous pooling (blood pooling in limbs)

  • Remove wastes (inorganic phosphates, H+ CO2)

interplay and quote to use

interplay is the use of all energy systems at any time, but the greatest contribution is determined by duration and intensity.

QUOTE = “All 3 energy systems contribute to ATP resynthesis throughout the physical activity. The intensity and duration of exercise will determine which one contributes the most at any time.”

what’s the acronym to use when stuck with an interplay question

• I - intensity

• D - duration

• R - rate

• Y - yield

3 causes of FATigue

F - feel depletion (PC / glycogen)

A - accumulation of bi-products

T - thermoregulatory fatigue

when answering fuel depletion questions

WHAT (causes the fatigue) - PC Depletion

WHY (does it fatigue us) - as PC depletes we anaerobic glycolysis contributions increase. This system produces ATP at a slower rate & creates fatiguing H+ ions

HOW (does it affect performance) - the athlete slows down / jumps less distance (fatigues) as rate and force of muscle contraction slows

LIP definition

is the highest intensity where lactate production equals lactate removal.

what happens when we exceed LIP (approx. when)

we have an increased contribution from the anerobic glycolysis system…

then causing a rapid accumulation of fatiguing bi-products such as H+ ions which inhibit muscular contractions

(approx. happens at 85% HR max)

acronym to remember / answer LIP questions

LIP is FAD / DAD

F = FINAL exercise intensity where lactate production equals lactate removal (definition)

A = this means the athlete can work at higher AEROBIC intensity

D = this delays the increasing contribution from the anerobic glycolysis system therefore resulting in less accumulation of H+ ions… and the ability to work harder for longer (performance link)

types of thermoregulatory fatigue

1. radiate heat to the environment

2. evaporative cooling via sweat

explain radiating heat

blood vessels at the active muscles and core vasoconstrict to send blood to skin, therefore vasodilation of the blood vessels at the skin.

this causes less blood and oxygen to reach active muscles therefore decreasing aerobic ATP production causing the athlete to slow.

explain evaporative cooling

the blood near the skin releases blood plasma which evaporates, and when cool wind passes over it it cools us / blood down

BUT less plasma means more blood viscosity and it’s harder for blood to travel around the body meaning less o2 and blood can be delivered to working muscles, reducing aerobic ATP production and slowing athlete

what happens during thermoregulatory fatigue (steps)

1. when muscles contract heat is formed

2. blood is redistributed (vasoconstriction and dialation) away from working muscles to skin

3. sweat is secreted causing thinker blood / dehydration

4. ^ less blood and O2 is able to get to working muscles

5. decreased aerobic ATP production OR increased contribution from the anaerobic glycolysis system (producing H+ ions)

6. performance decreases and athlete slows

   
   

how to answer thermoregulatory fatigue question

WHAT - expel heat (vasoconstriction and dilation) or secrete blood plasma

WHY - too cool body, but this will reduce blood and O2 at working muscles and the ability to produce aerobic ATP

HOW - muscles contractions slow OR increased anaerobic glycolysis contribution and therefore H+ ions

recovery strategies and when they are used

1. passive (short duration/high intensity = ATP-PC)

2. active (lower intensity = anaerobic glycolysis or aerobic)

what does a passive recovery do

• replenish PC

• restore oxygen and saturate myoglobin content

• resynthesis of ATP

what does an active recovery do

it increases EPOC but reduces recovery time ONLY when the anaerobic glycolysis and aerobic systems have been used for a long time.

• increased blood circulation and oxygen to muscles

• oxidise H+ ions at a faster rate

• remove lactate faster via muscle pump

• increase venous return, decrease blood pooling, prevent DOMS