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Реферат: Protein Essay Research Paper Creatine InformationCreatine is

Название: Protein Essay Research Paper Creatine InformationCreatine is
Раздел: Топики по английскому языку
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Protein Essay, Research Paper

Creatine Information

Creatine is a naturally occurring metabolite found in muscle tissue.It plays

an important role in energy metabolism, and ATP reformulating. Muscle

soreness, lactate build up, and fatigue are a direct result of depleted ATP

store. Creatine replenishes ATP stores, thus prolonging time to fatigue.

Creatine also increases available instant energy, increases muscular strength,

improves endurance, and reduces levels of metabolic byproducts such as

ammonia (Ammonia is produced at high levels during intense exercise,

ammonia is partially responsible for muscular fatigue). From our experience,

Creatine supplementation results in significant muscle accumulation and

increased muscular endurance in all of our clients. Weight gains from 4-14

pounds are common place with Creatine supplementation. Creatine loading

via supplemental feeding can also offer the potential for the following.

Improved Athletic Performance:

Maximizing the level of stored Creatine (20% or more) by supplemental

ingestion of Creatine Monohydrate, has been shown to extend peak athletic

performance for longer periods during short duration, high intensity exercise.

Stockpiling Creatine shortens the time necessary for the body to generate

replacement Creatine, thus significantly reducing muscle recovery time

between short duration, high intensity activities.

Increase Lean Muscle Mass:

Inactive or dystrophic muscle (such as occurs as a result of injury) has by

nature reduced levels of Creatine. Supplementation with Creatine

Monohydrate permits dystrophic muscle to work harder during therapy and

rebuild itself to its normal state.

Correct Creatine Deficiencies:

Disease or age-related Creatine deficiencies in the brain and skeletal muscle

can be improved by the oral administration of Creatine Monohydrate,

helping to restore a more

active, normal lifestyle.

How to Use Creatine

Loading / Maintenance Phase:

Take one to two scoops immediatley after workout, that’s it. Creatine is

best utilized when taken with a high glycemic substance such as (grape juice,

Ultra fuel, ect.)

Creatine Monohydrate – How Does It Really Works?

Glenn Peden offered the following from Tom McCullough via the FEMUSCLE list on Tuesday,

13June1995. It was forwarded to me in response to my call for information on Creatine.


My Dad said he read mail today. Hope he can answer all of your questions.

I have been powerlifting for 13 years. I lift in the 242 lb. weight class. I am also ranked #9 in the

USA. If you have not tried the creatine monohydrate, get some. Just a quick explanation of its

actions. I’m sure you know in order for a muscle to contract energy has to be released through the

breakdown of ATP. In strength training you are in an anaerobic system. The only way ATP is made

is through anaerobic glycolisis. ATP is also reformed in the anaerobic system when chemical

reactions take place in the muscle forcing the biproducts of ATP breakdown (ADP + Pi) back

together so muscular contractions can take place again. Here is where the creatine comes in to play.

The body has to hace creatine phosphate to force the ADP + Pi back together to reform ATP for

energy. Creatine phosphate is formed when a chemical reaction breaks down creatine monohydrate,

a natural dietary substance found in meats. The liver can synthesise creatine in small amounts but

most of the creatine we digest is stored in the muscles and bones for future use. However, especially

in diets low in protein, we do have limited stores and it does take time to release the creatine stores.

Red meat is the best source of creatine,however there is only about 1 g./lb. of meat. By taking

creatine supplements you are supersaturating the body with creatine phosphate stores. This will

enable you to have more creatine available to produce more ATP at a faster rate. Thus, more energy

is available per muscular contraction and ATP stores are restores quicker. This means for weight

lifters more max strength and quicker recovery.

The instructions for supplementation: 1st 5 days: 5g.4-6 x per day (this is the loading phase) after:

5-8g 30-45 min before workout/ 5g. after workout. Creatine supplements will also cause, in most

individuals intra cellular fluid retention. I have experienced 10 lb weight gains in first 2 wks. You

should also start experiencing strength gains after the first week. These gains wont be dramatic, like

steriods, but you will see a difference. Try it , I think you will like it. Texas A&M experimented with

it with a few players last season. This season they are putting the whole team on it because they got

such positive results with the few guys who tried it.

promote further gains in sprint performance (5-8%), as well as gains in strength

(5-15%) and lean body mass (1-3%). The only known side effect is increased body

weight. More research is needed on individual differences in the response to creatine,

periodic or cyclical use of creatine, side effects, and long-term effects on endurance.

Reviewers’ comments


Creatine is an amino acid, like the building blocks that make up proteins. Creatine in the form of

phosphocreatine (creatine phosphate) is an important store of energy in muscle cells. During intense

exercise lasting around half a minute, phosphocreatine is broken down to creatine and phosphate,

and the energy released is used to regenerate the primary source of energy, adenosine triphosphate

(ATP). Output power drops as phosphocreatine becomes depleted, because ATP cannot be

regenerated fast enough to meet the demand of the exercise. It follows that a bigger store of

phosphocreatine in muscle should reduce fatigue during sprinting. Extra creatine in the muscle may

also increase the rate of regeneration of phosphocreatine following sprints, which should mean less

fatigue with repeated bursts of activity in training or in many sport competitions.

So much for the theory, but can you get a bigger store of creatine and phosphocreatine in muscle?

Yes, and it does enhance sprint performance, especially repeated sprints. Extra creatine is therefore

ergogenic, because it may help generate more power output during intense exercise. In addition, long

term creatine supplementation produces greater gains in strength and sprint performance and may

increase lean body mass. In this article I’ll summarize the evidence for and against these claims. I’ll

draw on about 42 refereed research papers and four academic reviews to make conclusions

regarding the ergogenic value of creatine supplementation. In addition, I’ll provide 25 references to

studies published in abstract form, which report the most recent preliminary findings on creatine


Effects of Creatine Supplements on Muscle Creatine, Phosphocreatine, and


The daily turnover of creatine is about 2 g for a 70 kg person. About half of the daily needs of

creatine are provided by the body synthesizing creatine from amino acids. The remaining daily need

of creatine is obtained from the diet. Meat or fish are the best natural sources. For example, there is

about 1 g of creatine in 250 g (half a pound) of raw meat. Dietary supplementation with synthetic

creatine is the primary way athletes “load” the muscle with creatine. Daily doses of 20 g of creatine

for 5-7 days usually increase the total creatine content in muscle by 10-25%. About one-third of the

extra creatine in muscle is in the form of phosphocreatine (Harris, 1992; Balsom et al., 1995).

Extra creatine in muscle does not appear to increase the resting concentration of ATP, but it appears

to help maintain ATP concentrations during a single maximal effort sprint. It may also enhance the

rate of ATP and phosphocreatine resynthesis following intense exercise (Greenhaff et al., 1993a;

Balsom et al., 1995; Casey et al., 1996).

There is some evidence that not all subjects respond to creatine supplementation. For example, one

study reported that subjects who experienced less of a change in resting muscle creatine (*20

mmol/kg dry mass) did not appear to benefit from creatine supplementation (Greenhaff et al., 1994).

However, more recent studies indicate that taking creatine with large amounts of glucose increases

muscle creatine content by 10% more than when creatine is taken alone (Green et al., 1996a; Green

et al., 1996b). Consequently, ingesting creatine with glucose may increase its ergogenic effect.

Effects on Performance

Researchers first investigated the ergogenic effects of short-term creatine loading. In a typical study,

a creatine dose of 5 g is given four times a day for five to seven days to ensure that muscle creatine

increases. A control group is given a placebo (glucose or some other relatively inert substance) in a

double-blind manner (neither the athletes nor the researchers doing the testing know who gets what

until after the tests are performed). Most studies have shown that speed or power output in

sprints–all-out bursts of activity lasting a few seconds to several minutes–is enhanced, typically by

5-8%. Repetitive sprint performance is also enhanced when the rests between sprints don’t allow full

recovery. In this case, total work output can be increased by 5-15%. There is also evidence that

work performed during sets of multiple repetition strength tests may be enhanced by creatine

supplementation, typically by 5-15%. In addition, one-repetition maximum strength and

vertical-jump performance may also be increased with creatine supplementation, typically by 5-10%.

The improvement in exercise performance has been correlated with the degree in which creatine is

stored in the muscle following creatine supplementation, particularly in Type II muscle fibers (Casey

et al., 1996).

Researchers have now turned their attention to longer-term creatine supplementation. In these

studies, a week of creatine loading of up to 25 g per day is followed by up to three months of

maintenance with reduced or similar dosages (2-25 g per day). Training continues as usual in a group

given creatine and in a control group given a placebo. Greater gains are now seen in performance of

single-effort sprints, repeated sprints, and strength (5-15%).

Table 1 at the end of this article lists the references to positive effects of creatine on performance.

Theoretically, creatine may affect performance through one or more of the following mechanisms

(Table 2): an increase in concentrations of creatine and phosphocreatine in resting muscle cells; an

increased rate of resynthesis of phosphocreatine between bouts of activity; enhanced metabolic

efficiency (lower production of lactate, ammonia, and/or hypoxanthine); and enhanced adaptations

through higher training loads. Creatine supplementation during training may also promote greater

gains in lean body mass (see Body Composition below).

Not all studies have reported ergogenic benefit of creatine supplementation (Table 3). In this regard,

a number of equally well-controlled studies indicate that creatine supplementation does not enhance:

single or repetitive sprint performance; work performed during sets of maximal effort muscle

contractions; maximal strength; or, submaximal endurance exercise. What’s more, one study

reported that endurance running speed was slower, possibly because of an increase in body mass

(Balsom et al., 1993b).

In analysis of these studies, creatine supplementation appears to be less effective in the following

situations: when less than 20 g per day was used for 5 days or less; when low doses (2-3 g per day)

were used without an initial high-dose loading period; in crossover studies with insufficient time (less

than 5 weeks) to allow washout of the creatine; in studies with relatively small numbers of subjects;

and when repeated sprints were performed with very short or very long recovery periods between

sprints. It is also possible that subject variability in response to creatine supplementation may account

for the lack of ergogenic benefit reported in these studies. In addition, there have been reports that

caffeine may negate the benefit of creatine supplementation (Vandenberghe et al., 1996).

Consequently, although most studies indicate that creatine supplementation may improve

performance, creatine supplementation may not provide ergogenic value for everyone.

Body Composition

Although some studies have found no effect, most indicate that short-term creatine supplementation

increases total body mass, by 0.7 to 1.6 kg. With longer use, gains of up to 3 kg more than in

matched control groups have been reported (see Table 4 at the end of this article for references).

For example, Kreider et al.(1998) reported that 28 days of creatine supplementation (16 g per day)

resulted in a 1.1 kg greater gain in lean body mass in college football players undergoing off-season

resistance/agility training. In addition, Vandenberghe et al. (1997) reported that untrained females

ingesting creatine (20 g per day for 4 days followed by 5 g per day for 66 days) during resistance

training observed significantly greater gains in lean body mass (1.0 kg) than subjects ingesting a

placebo during training. The gains in lean body mass were maintained while ingesting creatine (5 g

per day) during a 10-week period of detraining and in the four weeks after supplementation


Findings like these suggest that creatine supplementation may promote gains in lean body mass

during training, but we don’t yet understand how it works. The two prevailing theories are that

creatine supplementation promotes either water retention or protein synthesis. More research is

needed before we can be certain about the contribution each of these processes makes to the weight


Side Effects

In studies of preoperative and post-operative patients, untrained subjects, and elite athletes, and with

dosages of 1.5 to 25 g per day for up to a year, the only side effect has been weight gain (Balsom,

Soderlund & Ekblom, 1994). Even so, concern about possible side effects has been mentioned in

lay publications and mailing lists. Before discussing these possible side effects, it should be noted that

they emanate from unsubstantiated anecdotal reports and may be unrelated to creatine

supplementation. We must be careful to base comments regarding side effects of creatine

supplementation on factual evidence, not speculation. But we must also understand that few studies

have directly investigated any side effects of creatine supplementation. Consequently, discussion

about possible side effects is warranted.

Anecdotal reports from some athletic trainers and coaches suggest that creatine supplementation

may promote a greater incidence of muscle strains or pulls. Theoretically, the gains in strength and

body mass may place additional stress on bone, joints and ligaments. Yet no study has documented

an increased rate of injury following creatine supplementation, even though many of these studies

evaluated highly trained athletes during heavy training periods. Athletes apparently adapt to the

increase in strength, which is modest and gradual.

There have been some anecdotal claims that athletes training hard in hot or humid conditions

experience severe muscle cramps when taking creatine, and the cramps have been attributed to

overheating and./or changes in the amount of water or salts in muscle. But no study has reported that

creatine supplementation causes any cramping, dehydration, or changes in salt concentrations, even

though some studies have evaluated highly trained athletes undergoing intense training in hot/humid

environments. In my experience with athletes training in the heat (e.g., during 2-a-day football

practice in autumn), cramping is related to muscular fatigue and dehydration while exercising in the

heat. It is not related to creatine supplementation. Nevertheless, athletes taking creatine while training

in hot and humid environments should be aware of this possible side effect and take additional

precautions to prevent dehydration.

Some concern has been raised regarding the effects of creatine supplementation on kidney function.

The body seems to be able to dispose of the extra creatine without any problem (Poortmans et al.,

1997). The extra creatine is eliminated mainly in the urine as creatine, with small amounts broken

down and excreted as creatinine or urea. No study has shown that creatine supplementation results

in clinically significant increases in liver damage or impaired liver function.

It has also been suggested that creatine supplementation could suppress the body’s own creatine

synthesis. Studies have reported that it takes about four weeks after cessation of creatine

supplementation for muscle creatine (Vandenberghe et al., 1997) and phosphocreatine (Febbraio et

al., 1995) content to return to normal. It is unclear whether muscle the content falls below normal

thereafter. Although more research is needed, there is no evidence that creatine supplementation

causes a long-term suppression of creatine synthesis when supplementation stops (Balsom,

Soderlund & Ekblom, 1994; Hultman et al., 1996).

Does creatine supplementation have undiscovered long-term side effects? Trials lasting more than a

year have not been performed, but creatine has been used as a nutritional supplement for over 10

years. Although long-term side effects cannot discounted, no significant short-term side effects other

than weight gain have been reported. In addition, I am not aware of any significant medical

complications that have been linked to creatine supplementation. Furthermore, creatine and

phosphocreatine have been used medically to reduce muscle wasting after surgery and to improve

heart function and exercise capacity in people with ischemic heart disease (Pauletto & Strumia,

1996; Gordon et al., 1995). Creatine supplementation may even reduce the risk of heart disease by

improving blood lipids (Earnest, Almada & Mitchell, 1996; Kreider et al., 1998). On the basis of the

available research, I consider creatine supplementation to be a medically safe practice when taken at

dosages described in the literature.

Determining whether creatine supplementation has any short- or long-term side effects is an area

receiving additional research attention. If there are side effects from long-term creatine

supplementation, an important issue will be the liability of coaches, trainers, universities, and athletic

governing bodies who provide creatine to their athletes. Anyone advising athletes to take creatine

should make it clear that side effects from long-term use cannot be completely ruled out, and that the

athletes do not have to take the supplements. It would be wise to have a formal policy for dosages

to reduce the chances of athletes taking excessive amounts.


Creatine supplementation is not banned, but is a nutritional practice that enhances performance

nevertheless unethical? Anyone pondering this question should consider that creatine

supplementation is a practice similar to carbohydrate loading, which is well accepted. Some are also

concerned that creatine supplementation could cause a carryover effect, whereby athletes who have

learned to take creatine are more likely to use dangerous or banned substances. Proper education

among athletes, coaches, and trainers regarding acceptable and unacceptable nutritional practices is

probably the best way to reduce any carryover.

How to Use Creatine

A typical loading regime for a 70-kg athlete is a 5-g dose four times a day for a week. Thereafter the

dose can be reduced to 2 to 5 g per day in order to maintain elevated creatine content. This

supplementation protocol will increase intramuscular creatine and phosphocreatine content and

enhance high intensity exercise performance. There is now some evidence that taking glucose (100

g) with the creatine (5 to 7 g) increases the uptake of creatine into muscle (Green et al., 1996a;

Green et al., 1996b). Consequently, I recommend that athletes take creatine with carbohydrate (e.g.

with grape juice) or ingest commercially available creatine supplements that combine creatine with

glucose. For athletes wanting to promote additional gains in lean body mass, I recommend 15 to 25

g per day for 1 to 3 months. Although many athletes cycle on or off creatine, no study has

determined whether this practice promotes greater gains in fat free mass or performance than

continuous use. More research is needed here.

Creatine supplements are good value. Creatine is now being sold for as little as US$30 per kg, or

about $0.60 per day when taking 20 g per day. Popular sports drinks are more expensive.

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