Creatine is a naturally occurring molecule in the body located primarily in skeletal muscle tissue (Mottram, 2005). Although most of the creatine found in the body is contained in skeletal muscles, it must first be metabolized by the liver and then transported to the skeletal muscles where it can be used.
The sole end product of creatine is called creatinine. Creatine is constantly being degraded to creatinine on a daily basis. So, the main difference between creatine vs creatinine is that creatinine is the end product of creatine that is ultimately passed through the kidneys and excreted through urine. In fact, the turnover rate of creatine to creatinine is around 2 g/day in a 70 kg person (Mottram, 2005).
Creatine is replaced in the body by means of endogenous synthesis and exogenous sources in the diet (Mottram, 2005). Foods that contain adequate amounts of creatine include meat and fish (which is why many vegetarians have low concentrations of creatine levels).
What is Creatine Used For?
The body uses three systems to supply the ATP (adenosine triphosphate) energy needed to live. One of those energy systems, called phosphocreatine/creatine, relies heavily upon creatine to replenish ATP energy supply during short term, high intensity exercise, such as sprinting and power lifting. During short term, high intensity exercise (lasting around 10 seconds or less) most of the energy supplied to the body is via the phosphocreatine/creatine energy system. As ATP is broken down to supply energy, phosphocreatine rapidly replenishes it, with the help from the enzyme creatine kinase. As exercise becomes longer, other energy systems, either glycolysis or oxidative, are needed to supply the required energy. Confused yet? Physiology of the body can be very confusing (God designed us to be extremely complex!). If you want to learn more about the process of the phosphocreatine energy system and how creatine and creatine kinase are involved, you can always Wikipedia creatine. The main thing to understand is that during maximal intensity exercise lasting around 10 seconds or less, creatine and creatine kinase are the main constituents that allow for the replenishment of ATP energy, which leads to my next question: why take creatine?
Why Take Creatine
So why take creatine? If you were paying attention above, you would have learned that creatine, along with the help from the enzyme creatine kinase, are the primary constituents involved in the replenishment of ATP energy during maximal intensity exercise lasting approximately 10 seconds or less. So, in theory, the more creatine that is available in the body, the more efficient ATP replenishment will be. As a result, use of creatine supplementation may prolong single bouts of high intensity exercise, as well as repeated bouts of high intensity exercise. Both possible outcomes are very appealing to athletes participating in sports consisting of brief periods of high intensity bouts of activity, such as sprinting, football, or bodybuilding. Additionally, the use of creatine causes muscle tissue to retain water, which has a positive effect on muscle development in a sense that increased muscle water has been shown to stimulate protein synthesis (Mottram, 2005).
Effects of Creatine on Repeated Bouts of High Intensity Exercise
The use of creatine supplementation can significantly elevate levels of creatine stored in the body. Makes sense right? Due to the increased levels of creatine, subjects taking creatine may be able to recover faster in between repeated bouts of high intensity exercise. Several studies have proved this theory correct.
One such study, conducted by Greenhaff and colleagues, consisted of 12 subjects who performed 5 bouts of 30 maximal knee extensions exercises with 1 minute of recovery between each bout. The subjects were then loaded with 20 g/day of creatine for 5 days and performed the knee extensions again. The results showed that creatine loading of 20 g/ day for 5 days allowed the subjects to increase peak muscle torque during the final 10 contractions for all 5 bouts (Mottram, 2005).
Another study, conducted by Balson et al. (Mottram, 2005), consisted of 16 subjects, divided into a creatine group and placebo group, who performed ten 6 second bouts of high intensity cycling with 30 seconds of rest in between each bout. The creatine loading amount of the creatine group was 20 g/ day for 6 days. Authors concluded that the creatine loading group were able to maintain the required cycling revolutions per minute (rpm) during the last 2 seconds of each bout, as opposed to the placebo group who failed to maintain after the 4th bout (Mottram, 2005). Additionally, during the 9th and 10th bout, the placebo group averaged 125 rpm while the creatine loading group averaged 138 rpm.
Effects of Creatine on Single Bouts of High Intensity Exercise
As we concluded above, the use of creatine may have a positive effect on the ability to perform repeated bouts of high intensity exercise. Well what are the effects of creatine on single bouts of high intensity exercise? Unfortunately, most studies have shown the use of creatine does not have a significant effect on single bouts of high intensity exercise. On the other hand, one study consisting of a single bout of 10 seconds of sprint cycling followed by 5 bouts of 6 second sprinting with a 30 second rest between bouts, did show an increase in power (Mottram, 2005). Apparently, the use of creatine may increase power in single bouts of high intensity exercise when fatigue is present from an earlier activity (Mottram, 2005).
Effects of Creatine on Strength
The major energy system involved in strength weight training is the phosphocreatine/creatine system. Most studies have shown a positive correlation between the use of creatine and strength. In fact, studies emphasizing the use of isometric, isokinetic, and isotonic strength exercises showed that the use of creatine improved strength between 6 and 28 percent (Mottram, 2005). Myself, along with many others, can attest to the fact that creatine definitely increases strength, which is why it is so popular amongst competitive sports and bodybuilding.
Effects of Creatine on Endurance
Although creatine plays a more prevalent role in high intensity, short bouts of exercise, some studies have shown that the use of creatine may have an effect on endurance activities. According to the finding of Bosco et al., subjects improved their 12 minute walk/run test after creatine loading with 5 g/day for 42 days. Unfortunately, when it comes to long endurance events, such as the 5k, the use of creatine has not shown any significant positive effects.
Creatine and Gaining Mass
One of the primary benefits that interest people about creatine is an increase in lean body mass. Williams et al. concluded that out of 58 studies assessing body mass changes when creating loading for 5 or 6 days, 43 reported significant increase mass (Mottram, 2005). One reason the subjects were gaining mass may be attributed to the retention of water weight in the muscles cause by the use of creatine. Regardless, the use of creatine in conjunction with a sound resistance training program can and probably will increase lean muscle mass to a certain extent. So, for those of you who are hard gainers and are interested in gaining mass, creatine may be just the thing you need! However, to weigh the benefits of taking creatine monohydrate, you should first decide whether or not creatine loading is beneficial.
Muscle Creatine Loading
Some people believe that creatine loading is not beneficial, while others believe it is absolutely necessary to achieve the positive effects of creatine. I disagree with the latter. Studies have shown that muscle creatine concentrations can still be significantly elevated using a lower creatine dose during creatine loading. In fact, one study reported that creating loading with just 3 g/day over a 4 week period resulted in muscle creatine concentrations comparable to those found when 20 g/day were taken over a 5 day span (Mottram, 2005). However, everybody’s body is different and therefore will respond differently to creatine loading. To be on the safe side, I would not recommend taking 20 g/day during the creatine loading phase. Although taking a lower creatine dose may delay potential effects of creatine, it is probably much safer for the body in the long run. Additionally, to maximize the potential effects of creatine, studies have shown that consuming at least 370 g of simple carbohydrates daily may enhance creatine concentrations in muscle by up to 60 percent (Mottram, 2005)!
Side Effects of Creatine
Many of the reported health problems that arose from the use of creatine have been attributed to creatine loading and taking too high of a creatine dose. Though very unlikely, one creatine side effect that can occur is renal failure. However, you would probably have to consume 20 g/day or more for an extended amount of time for this to occur. A study conducted by Juhn et al. concluded that creatine loading with 10g/day for 9 weeks failed to show any sign of impairment on the renal system, which proves how ill-informed people are about creatine and the possible side effects of creatine (Mottram, 2005).
Another report published in the Lancet in 1998 involved a football player who was supplementing with the use of creatine for 7 weeks (Mottram, 2005). Apparently, the football player had been suffering from a kidney dysfunction called focal segmental glomerulosclerosis. As a result of the use of creatine, creatinine clearance began to fall causing some negative side effects. This particular incident gave rise to the fact that the use of creatine by someone currently suffering from a kidney dysfunction is probably not the smartest idea. Additionally, in spite of the incident, many studies have shown no negative side effects of creatine on kidney function when taking creatine for a long or short period of time (Mottram, 2005).
Aside from the rare effects of creatine listed above, there are a few milder effects of creatine that you should be aware of. Common negative effects of creatine that people have complained about include dehydration; muscle cramps; gastrointestinal problems, such as diarrhea, gas, and stomach pain; and muscular injuries (Mottram, 2005). Obviously, dehydration can be easily avoided by drinking at least 8 glasses of water daily, if not more.
Typically, the majority of studies on the effects of creatine have not reported significant health complications as a result of the use of creatine. If you have normal kidney function and use creatine in moderation, chances are it is not going to negatively affect you. Taking 3 to 5 g/day for maintenance with adequate water intake is normally recommended by fitness experts (Mottram, 2005). However, as always, you should consult your doctor first to ensure you are healthy enough to include creatine in your strength weight training regimen.
Final Note About Creatine
Creatine is an essential natural food supplement composed of amino acids (Mottram, 2005). It is the primary source of ATP replenishment for the phosphocreatine/creatine energy system. Without it, we would be unable to replenish ATP energy needed to survive.
Scientists are starting to learn more about creatine and why the use of creatine is very beneficial to athletes engaging in repetitive, high intensity sports.
So why take creatine? A few noteworthy effects of creatine include:
- enhancing peak muscle torque during repeated bouts of high intensity exercise
- enhancing peak muscle torque during single bouts of high intensity exercise if previous fatigue is present
- increasing overall strength
- possibly improving times in short distance runs (not the 5k) or walks
- gaining mass
Although the effects of creatine can lead to serious side effects, most studies have proved otherwise. Subjects who suffered serious complications from the use of creatine monohydrate were typically ingesting a high dose of creatine for an extended period of time, which is never recommended. However, less severe effects of creatine that some experience includes gastrointestinal issues, such as gas, diarrhea, and stomach pain; muscle cramps; muscle injuries; and dehydration.
Well, now that you know some of the effects of creatine, hopefully you will be able to make a more informed decision about whether or not you want to make use of creatine. I have taken creatine in the past and the stuff worked incredibly for me. I gained strength and mass and did not lose it after I stopped taking creatine because I used creatine with protein the entire time thus gaining mass permanently.
Mottram, D. R. (2005). Drugs in Sport. Taylor & Francis Routledge. Retrieved from EBSCOhost.