Creatine and high-intensity performance: an energy source for maximum effort

Do you know that feeling when you are trying to give your absolute maximum? Whether it is a heavy set of squats, a maximum sprint on the track or an explosive take-off, at that moment your muscles are working flat out. These short but extremely demanding efforts require an enormous amount of energy in the shortest possible time. And this is exactly where creatine comes in.

ATP: the universal currency of cellular energy

To carry out any muscle work, the body uses a single direct molecule: adenosine triphosphate, or ATP. It is the universal fuel for muscle contraction. The problem, though, is that the muscles keep only very small stores of ATP – in fact the existing stores will last you roughly just 2 seconds of maximum effort. If you want to carry on, the muscle cells have to start restoring ATP immediately.

The phosphocreatine energy system

Creatine occurs naturally in the body, with the largest stores (about 95 %) held in skeletal muscle. Fast-twitch muscle fibres (type II), responsible for explosive strength and sprints, contain more than 30 % more creatine than slow fibres. Most of this creatine is stored in the form of phosphocreatine (PCr). It is precisely this source of energy that is important for strength training, explosive movements and so on, as opposed to the anaerobic (breaking down carbohydrates into ATP without oxygen - e.g. a 1500 m run) or the aerobic energy system (breaking down carbohydrates and fats with oxygen - endurance running at submaximal intensity).

During high-intensity exercise (e.g. a 100 metre sprint) the level of phosphocreatine starts to fall immediately – it readily gives up its phosphate group to the broken-down ADP and, without needing oxygen, creates new ATP molecules. Most of the stores are used up within 5 to 20 seconds at maximum effort.

Phosphocreatine has one more biological advantage. The chemical reaction in which ATP is restored from phosphocreatine actively uses up the free hydrogen ions (H+) that arise during muscle work. This buffers the rapid acidification (acidosis) of the muscle and helps prevent premature failure of the contractile mechanism. Put simply – it delays the feeling of burning and fatigue, so the muscles hold their maximum strength for longer.

Why is a normal diet not enough?

Our body can produce a certain amount of creatine itself in the liver from amino acids and we take in another part from food – specifically from meat and fish. Strict vegetarians and vegans, however, have an almost zero intake of creatine from food. Even in people eating a normal diet the natural muscle stores are not filled to the absolute maximum – the muscles constantly lose roughly 2 grams of creatine a day, which is converted into creatinine and excreted in the urine.

Specific benefits for performance

Research consistently shows that creatine supplementation demonstrably improves performance in both single and repeated sprints and in high-intensity exercise. The body is able to restore ATP sources faster during the short breaks between intervals, thanks to which you can manage more repetitions with a given weight during strength training.

An overview of the available literature shows that roughly 70 % of studies focused on sprints, strength training or interval work recorded a positive effect of creatine supplementation on strength, performance or force production (Greenhaff, Casey et al., 1993).

How should creatine be dosed?

If you want to maximise your muscle stores, you have two proven options:

Conclusion for athletes

If your sport requires repeated explosiveness, lifting weights or lightning-fast sprints, creatine is an absolutely unbeatable supplement that will take your performance to a higher level.

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