I often wondered why anaerobic and aerobic exercises are named as they are. Surely, while running, you should not be out of breath to avoid “switching to anaerobic metabolism”. But why is it called anaerobic metabolism when doing short bursts of weight training even though I am barely out of breath? Recently, I refreshed my biology class 11 knowledge with the help of wikipedia and want to share my findings. This is just a very brief overview and lacks the scientific depth.
Adenosine Triphosphate (ATP)
To make a muscle work it needs energy, which is primarily generated by ATP splitting a Phosphat MOlecule and changing to Adenosindriphosphat, in the process releasing energy. However, this energy is only short lived, and we only have a very limited amount of ATP readily available in our muscle cells, which would only amount to at max 3s of muscle contraction. To resynthesis the ATP there are multiple ways to do so, which we will shortly explore and also relate to how exercising can increase our performance.
Anaerobic and Aerobic Metabolism
Anaerobic and Aerobic Metabolism
The primary energy source for cellular functions is Adenosine Triphosphate (ATP).
ATP and creatine phosphate are readily available in muscle cells and can be quickly utilized for immediate energy needs. However, our muscles also have access to other energy substrates like glycogen, fats, and proteins. These energy sources need to be metabolized first to produce ATP, providing a more sustained energy supply, albeit a little bit slower.
Anaerobic Metabolism
Generates energy without the use of oxygen. It’s fast but produces limited energy.
Phosphatmetabolismn
The body relies on stored ATP and creatine phosphate in the muscle cells for energy during these bursts. Because these energy reserves are small, anaerobic metabolism can only sustain high-intensity activity for a few seconds to about a minute.
ATP + H2O → ADP + P + Energie
ADP + Creatine Phosphate → ATP + Creatine
Anaerob lactacid
lactat erzeugung => lactat threshold
Lactate = a byproduct of fast, oxygen-limited energy production
The fatigue comes from hydrogen ions (H⁺) that are released alongside lactate.
- ese lower your muscle pH (more acidic).
- This interferes with:
- Muscle contraction
- Calcium release
- Nerve signaling
it makes lactate when it needs anaerobic energy, usually because oxygen delivery is maxed out or too slow
You build the engine with Zone 2,
You upgrade the fuel system with threshold work,
You push the RPM limit with VO₂ max intervals.
| Capacity | Meaning | How You Train It | Zone |
|---|---|---|---|
| Aerobic preference | Use oxygen longer, burn fat, spare carbs | Zone 2, long easy runs | Zone 2 |
| Lactate clearance | Recycle/remove lactate & buffer acidity | Threshold/tempo runs | Zone 3/4 |
| Peak oxygen delivery (VO₂) | Use the most oxygen possible at max work | VO₂ max intervals | Zone 5 |
Aerobic Metabolism
This process requires oxygen and produces significantly more energy than anaerobic metabolism, though at a slower rate. It utilizes carbohydrates and fats as fuel sources, ensuring a continuous supply of energy over longer periods.
1 Glucose + 6 O2 + 32 ADP + 32 P → 6 CO2 + 6 H2O + 32 ATP
Processing Glucose may generae as much as 15 times ATP in comparison to anaerob metabolism.
Training Implications
Weight Training: Primarily involves anaerobic metabolism due to the need for quick energy bursts during short, intense efforts. The body relies on ATP and creatine phosphate for immediate energy. Supplementing with creatine can enhance the storage of creatine phosphate in muscle cells allowing for a greater reserve of quick energy. A side effect is that the high concentration of creatine in the muscle cells draws water into the cells through osmosis.
Cardio Training: Relies heavily on aerobic metabolism. Activities like running, swimming, or cycling demand sustained energy over a prolonged period, making efficient use of oxygen to convert carbohydrates and fats into ATP. The process of utilizing fats as an energy source typically starts after around 20 minutes of exercise.
