What is creatine?
The most common form of creatine is creatine monohydrate. It’s made from amino acids that are naturally produced by the body and obtained from dietary sources such as meat and fish.
How does creatine work?
Before we get into what creatine does, it helps to understand its role in muscle contraction.
Within our bodies—and more specifically in our muscles—creatine binds with phosphate to form a usable, high‑energy compound called creatine phosphate (CP). Muscle contraction is powered by breaking down ATP (adenosine triphosphate), which is the only direct energy source your muscles can use for contractile activity.
When ATP is broken down, we have enough energy to fuel maximal effort for only about 4–6 seconds. Because this isn’t very long, ATP needs to be regenerated quickly from its by‑product, ADP (adenosine diphosphate), back into ATP. This regeneration happens in a fraction of a second and is achieved via three main energy pathways. One of these pathways uses creatine phosphate as the energy source to convert ADP back into ATP.
Creatine, in the form of creatine phosphate, simply acts as a high‑energy reserve that helps regenerate ADP back to ATP. This happens while slower metabolic pathways (the other two energy systems that also regenerate ATP) are ramping up to meet the increased demand. Our muscles actually store more creatine phosphate than ATP. Together, stored ATP and the near‑instant regeneration of ATP via creatine phosphate allow for maximum muscle power for around 10–15 seconds—enough to complete a hard set of roughly 6–8 heavy bench presses.
What does creatine do?
We now know what creatine is and how our bodies use it, so let’s look at how it can help your workouts and support muscle hypertrophy (increased muscle size).
The theory behind using creatine for muscle hypertrophy is that supplementing with it can increase creatine phosphate stores in the muscles. This, in turn, can slightly increase the maximum power your muscles can produce at any one time and may allow you to perform an extra 2–3 reps per set. Over time, this additional work can lead to more muscle fibre damage. Provided you have a good diet and adequate rest, your muscles can then repair and rebuild, leading to increased muscle size (hypertrophy).
Summary
Although creatine does not directly cause muscle growth, it can support it by allowing your muscles to perform additional reps at high intensity. This increased workload leads to greater muscle damage and, in turn, more muscle repair and growth over time.
Side Effects
As with any supplement or performance‑enhancing product, side effects are sometimes reported, and creatine is no exception. Some of the most commonly reported side effects of creatine use are listed below:
- Oedema (water retention), especially in women
- Undesirable weight gain (through water retention)
- Muscle cramps and spasms; gastrointestinal (abdominal) discomfort
- Muscle tears
- Nervous twitches
- Heightened awareness and insomnia
In addition to these side effects, it’s possible there are others. Supplements affect people differently, and many people who use creatine do not report any side effects at all.