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In our competitive society, being the best is of utmost importance. Athletic performance is no exception, and athletes are constantly striving to find new ways to train which will help them to become the best. Many supplements promising results have come and gone, but creatine may actually be able to deliver improved athletic performance. Many athletes are currently supplementing their diets with creatine to increase their strength, muscle mass, and weight by providing their bodies with more available energy, thus reaching new heights in athletic performance.
Creatine is a nutrient that is found naturally in the diet as well as the human body. The primary dietary sources of creatine are raw beef and fish, as heating tends to destroy creatine . However, moderate increases in meat consumption are unlikely to increase muscle creatine levels because one must consume approximately 12 pounds of meat per day to achieve the same creatine levels as supplementation. When dietary consumption is inadequate to meet the body's creati.ne needs, it is manufactured in the liver and kidneys from a combination of the amino acids arginine, glycine and methionine. Creatine is present inside muscles, especially skeletal muscles. In the muscles, creatine. is used to form creatine phosphate (CP), a potent chemical which can indirectly supply the energy our muscles need to contract, especially for quick and explosive movements such as in sports.
All work done in human cells (including contracting muscles) is fueled by the breakdown of adenosine triphosphate (ATP) to adenosine diphosphate (ADP). ATP is created inside cells by metabolizing carbohydrate, fat , or, protein in the presence of oxygen. (http://www.creatine.com/creatine.html#source)
Usually relying on ATP production for energy is alright except for two problems. The first is that ATP is produced at a slow rate, too slow to supply the energy needed to run a 200-meter sprint, for example. The second problem is that ATP production takes a while to get started. As one goes from rest at the starting line of a race to running at race speed, for example, the traditional method of ATP production does not begin working at full capacity until a couple of minuets have passed. Another source of energy is therefore needed to get one through the early moments of a race or workout. (http://www.creatine.com/creatine.html#source)
Creatine phosphate serves as this other source of energy. CP donates its phosphate to ADP, thus creating the ATP needed to make muscles work. It has been hypothesized that by increasing the amount of free Creatine in the diet one could increase the amount of creatine phosphate in skeletal muscles which would then provide better availability of high energy phosphate for energy production during muscle contraction. If one were to start running at top speed from a standing start, creatine phosphate would supply almost all of the necessary energy during the first six seconds of the run. Http://www.creatine.html#source)
Creatine phosphate also acts as a ''buffer'' which helps to combat jumps in muscle acidity during intense exercise. Efforts. CP helps to create ATP, it consumes excessive amounts of hydrogen ions which are released by lactic acid which can build up in muscle cells during intense efforts. Because. excess hydrogen ions interfere with muscle contractions, this "buffering" action helps to delay fatigue allowing for longer workouts. (http://www.creatine.com/creatine.html#source)
Increasing creatine phosphate concentrations in the muscles is made possible by supplementing one's diet with creatine. Research indicates that there are two phases for maximizing the benefits of creatine. The first phase is a creatine loading phase lasting for five days. Subjects take one teaspoon (about 5 grams), 4 to 6 times daily mixed in water. This method is shown to rapidly maximize Creatine levels in the skeletal muscle. In the maintenance phase, subjects took one teaspoon (5 grams) once or twice a day mixed in water and their creatine levels were maintained. (fttp://www.creatine.com/creatine.html#source)
Companies all over the United States are advertising creatine as a supplement which will enhance athletic performance by increasing muscle strength, promoting muscle mass growth which leads to weight gain, increasing the storage of "instant" anaerobic energy, and improving endurance by delaying' fatigue. Numerous college level trainers report that the athletes who use creatine experience a delay in muscle cramping and soreness. (Http://family.med.und.nodak.edu/course/ fmed9320/creatine/discuss.HTM)
Nearly every fitness magazine contains ads for creatine, in which professional athletes endorse the product and give personal testimonies promising incredible gains. Bill Phillips, editor of Muscle Media 2000, claims he gained nine pounds and his strength shot up incredibly after being on creatine for only ten days. Further, he tells of a friend whose strength (measured by the number of reps lifted at a certain weight) increased by 25% in only five days. Consumers must beware of personal testimonies, however, because most athletes are paid to endorse the product.
There is overwhelming evidence which shows that creatine supplementation does cause an increase in the amount of creatine phosphate in muscles. Harris et al (1992) conducted a study examining creatine content in the quadriceps femoris muscle in 17 subjects after supplementation of 5 g of creative monohydrate 4-6 times a day for two days. The results found a significant increase in the total creatine level in all subjects but the results were especially noticeable in those with the lowest muscle creatine store at the start of the study. These subjects were most often vegetarians. (Http://family.med.und.nodak.edu/course/fmed9320/creatine/discuss.HTM) To determine whether exercise could affect the amount of creatine absorbed by muscles, some of the participants followed a unique training program. During supplementation, they pedaled a bicycle ergometer for one hour each day while using only one leg to supply the pedaling force. With supplementation, the unexercised legs increased their creatine levels by about 25 percent, but the exercised legs increased their creatine levels by 37 percent. It is hypothesized that exercise increases the flow of blood to the muscles or changes the rate at which muscles absorb creative from the blood, thus improving the creatine loading effect. Another study conducted by Febbraio et a]. (1995) replicated the results obtained by Harris et al (1992).
Several studies also show that creatine supplementation does cause an increase in muscle strength. Earnest et al (1995) conducted a study investigating the influence of creatine monohydrate supplementation on muscular power and strength in 10 experienced weight trained male subjects. Three series of high intensity, anaerobic type muscular workouts were used. The first series consisted of three consecutive 30 second Wingate bike tests, followed by five minuets of rest. Peak anaerobic power was defined as the greatest power achieved in a given five second work interval. Anaerobic work was defined as the total amount of work performed in a 30 second period. The second series used a one repetition maximum (lRM) free weight bench press as a test of muscular strength. The third series utilized complete lifting repetitions at 70% of the bench press IRM until fatigue. Fatigue was defined as the inability to complete one lifting repetition or the inability to maintain a lifting cadence of one second eccentric and one second concentric (lifting and lowering the weight). Total lifting volume was calculated as 70% of pre-test IRM multiplied by the number of complete lifting repetitions. Subjects received either a glucose placebo or creatine monohydrate supplement in a double blind fashion. (After 14 days of supplementation, each subject was re-tested on the Wingate bike tests. Re-testing for the weight lifting trials was done after 28 days of supplementation.
Within the creatine group, total anaerobic work from the Wingate tests was significantly higher during all post-test trials. The increases were 13% for series one, 18% for series two and 18% for series three. No changes were noted in the placebo group. Greater total anaerobic work resulted from the creatine subject's ability to achieve and maintain higher levels of anaerobic power consistently over- each five second time interval. Bench press IRM increased 6% in the creatine group. Total lifting volume was significantly higher within the creatine group, whether expressed in absolute terms (26%) or relative terms (29%). Increases in the total lifting volume were associated with the ability of the creatine group to perform 26% more lifting repetitions. The authors conclude that the ability of the creatine group to perform a greater total lifting volume demonstrates the effectiveness of creatine as an ergogenic aid.
In Hultman's study (cited in Anderson, 1974) these results were replicated. Each day, creatine was given in six separate doses of five grams a day. During the six-day period, five other Estonian runners of comparable ability received a glucose placebo instead. All runners were unaware of the actual composition of their supplements. Before and after the six-day supplementation, the athletes ran four 300-meter and (on a separate day) four 1000-meter intervals, with three minutes of rest between the 300-meter intervals and four minutes of rest between the 1000-meter intervals. Improvement on the final 300-meter interval (from pre-to-post supplementation) was more than twice as great for creatine users, and improvement was more than three times as great for creatine supplements in the final 1000-meter interval. Total time to run all four 1000-meter intervals improved from 770 to 757 seconds after creatine supplementation. In comparison, the placebo group actually slowed from 774 to 775 seconds.
The majority of studies support the claim that creative increases muscle strength. However, a study conducted by Cooke et al (cited in http://family.med.und.nodak.edu/course/fmed 9320/creatine/discuss.HTM) compared creatine supplementation to placebo supplementation and examined power output and fatigue. Their results showed that "oral ingestion of creatine had no significant effect on any of the mechanical parameters associated with short-term power output and fatigue during single bouts of maximal exercise performed on a specially modified cycle ergameter.''
The Study conducted by Earnest et al (1995) assessed body composition using hydrostatic weighing techniques. 'There was a significant increase in body weight (86.5 +-13.7 vs. 88.2 +-14.1 kg) as well as a nonsignificant increase in calculated fat free muscle mass (77.6 +-10.8 vs. 79.2 +-11.6 kg) +or the creatine monohydrate group. No changes in body weight (82.6 -+ 2.2 vs. 62.5 +- 1.8 kg) or fat -free mass (74.7 +- 6.6 vs. 74.4 +- 6.2 kg) were noted for the placebo group. However, the authors have not been able to conclude whether or not creatine monohydrate is directly responsible for the increase in body weight. However, they do hypothesize that with creatine supplementation individuals suffer less muscle fatigue at a given intensity level, thus allowing for more intense and longer workouts. In order for a muscle to grow massively, it must be stimulated by a greater workload. This increased overload is accomplished by increasing intensity, increasing duration, or increasing exercise frequency. Therefore creatine allows for longer and more intense workouts, thus creatine may lead to greater muscle mass.
In Hultman's study (cited by Anderson, 1994) creatine supplementation was very important during the last interval of each workout. Creatine supplementers doubled their advantage during the final 300-meter interval and tripled their advantage in the closing 1000-meter sprint. This supports Hultman's hypothesis that creatine is likely to be most helpful when lactic acid levels are highest and fatigue is greatest. Hultman thus feels that creatine serves as a ''buffer'' lowering lactic acid muscle burn and delaying fatigue, thus allowing an athlete to perform longer workouts.
In contrast, Balsom at al (1993) investigated the influence of creatine supplementation on endurance exercise performance in the form of a 6 km run and showed that creatine supplementation does not enhance performance or increase peak oxygen uptake during prolonged continuous exercise. There was actually decreased performance in the creatine supplementation group, which may be attributed to the participants weight gain.
In support of Balsam et al (1993), Febbraio et al (1995) conclude that creatine supplementation "may not increase performance during exercise where a significant proportion of energy is derived form aerobic metabolism." This aerobic metabolism occurs during more prolonged, sustained exercise as opposed to anaerobic metabolism which occurs during fast, nonsustained muscle contractions. It is therefore more likely that if creatine supplementation has an effect it will only be seen during brief, anaerobic exercise such as sprinting or weight lifting.
Companies selling creatine products claim creatine is a safe product free of side effects. They, back this claim by noting that creatine is a nutrient that is found naturally in muscles (ranging from 100-115 grams) and is also produced by the body when dietary consumption is inadequate. Fttp://www.creatine.com/creatine.html#source)
No negative side effects have been noted among research with the recommended levels of supplementation. However, some people have reported nausea and diarrhea with high doses (Sahelian, 1997). It should also be noted that the studies that used high dosages of creatine, such as 20-30 grains daily, took. place over a time period of a month or less. There have been no controlled studies of long-term use of high doses of creatine. Despite this, many people have safely gained muscle and increased endurance by cycling their use of creatine.
Salsom, P.D., Harridge,S.D.R., Soderlund,V..., Siodiri,B. & Ekblom,B.
(1993). Creatine supplementation per se does not enhance endurance performance.
Acta Physiologica Scandiavica, 149, 521-523.
Cooke, W.H., Grandjean, P.W. & Barnes, W.S. (1995). Effect of oral
creatine supplementation on power output and fatigue during bicycle ergometry.
Journal of Applied Physiology, 78(2), 670-673
Earnest, C.P., Snell, P.B., Rodriguez, ., Almada, A.L. Mitchell, T.L.
(1995). The effect of creatine monohydrate ingestion on anaerobic power
indices, muscular strength and body composition. Acta Physiologica Scandiavica
Febbraio, M.A., Flanagan, T.R., Snow, R.J., Zhao, S. F., Carey, M.F.
(1995). Effect of creatine supplementation on intramuscular Tcr metabolism
and performance during intermittent, supramaximal exercise in humans. Acta
Physiologica Scandiavica, 155, :387-395.
Harris, R.C., Soderlund, K. & Hultman, E. (1992). Elevation of creatine
in resting and exercised muscle of normal subjects by creatine supplementation.
Clinical Science 83, 367-374.
Sahelian, R. (1997). Creatine: Nature's muscle builder. Let's Live,
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