24 kJ

Energy is required for muscle to perform work. This energy is released from the combustion of carbohydrate, lipids, protein and is stored as chemical energy in the form of adenosine triphosphate (ATP). Subsequently the degradation of ATP provides free energy that can be converted to mechanical energy. Muscle can perform 24kJ of work for every mole of ATP degraded.

Exactly how we get to creating ATP, degrading ATP and utilising everything is highly complex and not fully understood. All the different systems that lead to this including the tricarboxylic acid cycle, electron transport chain, oxidative phosphorylation, purine nucleotide pool, different substrate sources, enzymes and training status means there are too many factors to fully control. While so much is known, there is so much that isn't known.

Why am I taking this line?

The trend in so-called advice for the best way to train is getting annoying. The number of experts seems to be increasing while the knowledge or wisdom doesn't seem to be keeping pace. Too many people who have participated in some training program are now training others by the same method they used.

Marketing in some of the trends uses arguments on how the energy systems are trained. These arguments are often not based on accurate knowledge or established science. Instead they are theories. There is school of thought that is stating there is better performance benefits from using anaerobic style intervals, while dropping long distance oxidative training. The argument continues that oxidative training makes you weak and is detrimental to health. On the extreme other side of the training scale is that you get better long term benefit from lots of long distance, oxidative training and only need a limited amount of harder work thrown in.

Many training regimens have plenty of merit. The key problem I have is many are being promoted as "the only way to train" or as "the best way to train". I don't buy it. No one truly knows this. People do have ways that get results. However, there are more than one way to achieve the performance we are working towards. Training programs are now being promoted like many supplements. Some work, some claims are too good to be true, and the knowledge from which they come from often leads something to be desired.

So how does knowing that one mole of ATP can translate into 24kJ of work by muscle?

In reality it probably doesn't. Beware of programs that quote irrelevant science.


  1. Great post. "A little bit of knowledge can be a dangerous thing". I always hate it when coaches try to justify workouts with pseudoscience. I think the best evidence for the efficacy of a training method is past results with that method.

    That said, although it may be the case that we don't fully understand the process of ATP creation and degradation at a cellular level, I have to ask: "does it matter?". Bringing biochemistry into the equation overcomplicates things I feel.

    We may not know the best way to train, but ultimately the concept of training specificity is all that matters. In order to race fast, you have to run fast and everything else is merely peripheral.

  2. Good post Jason. I don't buy it either. There's no best way to train. Even for runners doing the same event, whether it be the 100m, the 10k or the marathon. Individualisation is the best training plan.


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