ib sport energy systems test

What energy/fuel does the body make?

Cellular fuel called ATP

How many energy systems (engines) are there?

three

3 energy systems

phosphagen, glycolytic, oxidative

Phosphagen system

Ultra-fast, immediate energy for short, explosive bursts, runs out very quickly. (0-10 seconds, like max sprint or heavy lifting)

Glycolytic system

Fast energy for high-intensity efforts, burns carbs and produces lactic acid/lactate. (10 seconds to ~2 minutes, like a 400m run)

Oxidative system

slow, but long-lasting energy using oxygen, can burn carbs, fats, and even protein. (for long-distance runs or sitting at your desk)

Energy continuum

your body rarely relies on just one system. They all work together on a spectrum (continuum). Which system does the heavy lifting depends on how hard and how long you are moving

aerobic

with oxygen

anaerobic

without oxygen

at rest/LIGHT exercise

the OXIDATIVE (aerobic) system does almost all the work

hard, fast, or sudden bursts

the ANAEROBIC systems (phosphagen and glycolytic) instantly step in because they don’t need oxygen to make quick energy

what fuels the phosphgen system (immediate energy)?

Creatine Phosphate/Phosphocreatine (CP/PCr) and ATP stored in the muscle cells

How does the fuel source for the phosphagen system work?

muscles store a very small amount of ready-to-use ATP, and Creatine Phosphate, which rapidly donates a phosphate group to remake ATP instantly

what fuels the Glycolytic system (short-term/fast energy)?

ONLY carbohydrates:

• Muscle glycogen (in glucose in muscle)

• Blood glucose (sugar in blood stream)

How does the fuel source for the glycolytic system work?

breaks down glucose/glycogen through anaerobic glycolysis (without oxygen) to quickly generate ATP, producing lactate as a byproduct

what fuels the oxidative system (long-term/ aerobic energy)?

Carbs, fats, and (as a last resort) protein

• carbs: used during moderate to high intensity aerobic work (temp runs, cycling hills)

• Fats (triglycerides/free fatty acids: the main fuel source at rest during low intensity, long duration exercise (walking, easy jog) *provides almost unlimited supply of energy, but requires lots of oxygen to break down

• protein (amino acids): contributes a very small amount, used mostly during extreme endurance events or prolonged starvation when carb stores are depleted

How does the fuel source for the oxidative system work?

uses oxygen in the mitochondria to break down carbs and fats completely into large amounts of ATP

3 energy systems from highest to lowest intensity:

1) Phosphagen system (used 0-10 secs)

2) Glycolytic system (used for 10-secs-2mins: ie 400 m run)

3) Oxidative system (eg jogging, walking, resting)

What is VO2 Max?

the maximum amount of oxygen your body can take in and use during intense exercise. (think of it as your body’s overall aerobic engine size)

What affects your VO2 max?

• age (peaks in young adulthood and gradually declines)

• gender (men have higher values due to larger heart size, muscles mass, hemoglobin levels)

• body composition (more lean muscle mass = higher oxygen demand and capacity, higher body fat lowers relative VO2 max)

• fitness & lifestyle (training increases it; smoking, poor diet, or sedentary living lowers it)

Running economy

matters for endurance.

how efficiently your body uses oxygen to run at a steady pace - essentially your body’s gas mileage

(less oxygen you waste to maintain speed, the batter your running economy is)

movement efficiency

determines how much energy you waste while moving.

2 people with the same VO2 max will perform differently if one has a much smoother, more efficient running stride

What is the lactate inflection point (LIP)?

The hardest effort level you can maintain where your body is still able to clear out lactate as fast at it produces it

what is the threshold of LIP

if you push past this intensity, lactate builds up in your muscles and blood faster than your body can remove it, causing rapid fatigue and that burning feeling in your muscles

what is the difference between lactate and lactic acid?

lactic acid splits immediately in the body INTO lactate and hydrogen ions

Lactate = useful fuel recycled for energy

hydrogen ions = acid that causes muscle burn and fatigue

lactic acid = the full “ballon” (combination of lactate and hydrogen ions)

Oxygen deficit

when you start exercising, your oxygen intake takes a couple of minutes to catch up to what your body actually needs. you build up an “oxygen debt'“

EPOC (Excess Post-Exercise Oxygen Consumption)

after you stop exercising, your heavy breathing continues. This extra oxygen intake helps your body pay back the oxygen debt and return to its normal state (homeostasis)

How many phases of EPOC are there

2 phases:

fast and slow

Fast phase

lasts a few minutes right after exercise. restores ATP stores and refills oxygen levels in your blood and muscles

Slow phase

lasts several hours. clears out lactate, lowers body temp, slows heart beat, and repairs tissue