Creatine is a natural energy source used for muscle contractions. The body makes about half of its creatine supply in the liver and kidneys and gets the other half from meat in the diet.
Most creatine is stored in the skeletal muscles. The body releases it during physical activities, helping maintain a continuous supply of energy. Many athletes use creatine supplements to improve performance, and studies indicate that they may have real effects on the body.
The body tightly regulates creatine, balancing its formation and excretion. In the body, it binds with phosphate to create creatine phosphate. To understand how creatine works, it helps to understand a little about ATP and ADP.
ATP, or adenosine triphosphate, provides energy for almost everything the body does. To do this, it releases a phosphate group, which produces heat energy. After it loses a phosphate, ATP becomes ADP or adenosine diphosphate. To continue to power the body, ADP must convert back into ATP. Creatine, in the form of creatine phosphate, donates its phosphate to ADP, turning it back into ATP.
Essentially, creatine helps rebuild the body's power supply.
Generally, research indicates a positive relationship between creatine supplementation and exercise performance. One study showed that a weeklong loading period and daily maintenance dose of creatine supplements combined with heavy resistance training resulted in a significant increase in performance over 12 weeks.
Although not all studies on creatine have the same results, overall, creatine supplements combined with resistance training seem to enhance performance, endurance, and muscle size.
Creatine can also improve performance in anaerobic exercise—those that happen in the absence of energy. Generally, these exercises are more intense than aerobic exercise, which uses oxygen for energy.
Examples of anaerobic exercises include sprinting, weight lifting, and high-intensity interval training. Studies show that creatine can enhance performance for these short, intermittent movements.
When using creatine supplements, the most common method is to take a loading dose for a short period and then continue with a maintenance dose. Research shows that taking creatine supplements in this way can increase performance in short periods.
Various studies looked at different periods and the athletic performance of study participants. For example, one study reported significant improvements in back strength after only five days. Another demonstrated that young adult male study participants saw improvement in squat strength, bench press, and power output after only ten days of supplements.
Creatine also seems to have long-term benefits. While short-term use can affect high-intensity exercise directly, extended use of creatine supplements supports increased training volumes and training quality.
What's more, these benefits seem to develop in study participants who were previously sedentary. Researchers in one long-term study reported that participants who took creatine had more significant increases in exercise volume and intensity as the study progressed.
Other studies show that creatine may also affect speed and agility. One study involved 14 elite female soccer players who took 20 grams a day of creatine or a placebo for six days. The creatine group had significantly faster agility runs than the placebo group on three of the test days.
Similar studies showed improvements in speed in various sports, including football, handball, track, and swimming, although other studies have shown that creatine had no effect.
Athletes also take creatine to speed up recovery time. The mechanism behind this goes back to the idea that creatine phosphate speeds up ATP regeneration, therefore increasing the delivery of ATP to muscles and improving recovery, especially after bouts of intense and intermittent (anaerobic) activity.
Creatine may also reduce the inflammatory response after exercise, lessening muscle damage and soreness.
Studies also indicate that not everyone responds to creatine in the same way. Some people, called non-responders, do not get the same results as other members of the study group.
One study saw huge variations in the 11 male participants: three responded to the creatine, five somewhat responded, and three did not respond at all.
Creatine is a safe supplement with a few side effects, including possible liver and kidney damage, bloating, and muscle cramps. Other side effects include water retention and water weight.
Research does not indicate any harmful long-term effects on healthy individuals taking creatine, but taking creatine can be dangerous for people trying to lose weight or those who are dehydrated.
There are some safety issues to consider when taking a creatine supplement. Supplements are not regulated and may vary in quality and purity.
People with kidney disease should talk to their doctor before taking a creatine supplement, as it can be hard on the kidneys and make the condition worse. Doctors are also not sure if creatine affects the brain, heart, or liver long-term or how it interacts with prescription or over-the-counter medications.
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