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Creating strength through creatine. (Healing Options).

If you wander through health-food stores, you may see muscular bodybuilders checking out creatine supplements. Many athletes now consume them to build strength and enhance athletic performance, especially for physical efforts requiring energy bursts.

Since English Olympians initially brought attention to creatine's performance-enhancing benefits at the 1992 Barcelona Games, creatine's popularity has skyrocketed. Its effectiveness is now supported by numerous scientific studies, including those suggesting benefits for people with physical disabilities.

Our bodies contain more than 100 grams (28 grams = 1 ounce) of creatine, mostly in our muscles, heart, brain, and testes. Physical activity stimulates primarily the liver to produce about two grams of creatine daily from three key amino acids: glycine, arginine, and methionine. Creatine is then sent through the blood and transported into muscle cells.

Creatine can also be provided by diet, especially one rich in meat and fish. Vegetarians, however, often lack not only creatine but also the methionine precursor needed for internal production. For comparison's sake, a pound of meat contains about 40 times more creatine (two grams) than a pound of milk.

Creatine-generated Energy

Most muscle creatine is converted into the energetically powerful creatine-phosphate. The high-energy molecular bond connecting creatine to the phosphate group is an energy source that can quickly fuel muscle activity. This fueling, however, is mediated through the creation of yet another powerhouse molecule called adenosine triphosphate (ATP).

ATP is extremely important because it is the body's energy currency, expended to drive most biochemical processes. Like creatine-phosphate, ATP's terminal phosphate group is connected by a high-energy bond that when severed provides energy needed for muscle contraction.

Under more constant or endurance working conditions, the body obtains ATP by metabolizing carbohydrates and fats, a relatively slow process that cannot generate immediately needed ATP energy.

When energy bursts are required, the body instead uses creatine-phosphate. Specifically, the phosphate group on this molecule is transferred to replenish spent ATP, transforming it into its energetically powerful form. During rest periods, creatine-phosphate is then replenished by the ATP generated by the slower metabolic processes.

If intracellular creatine-phosphate levels can be increased through supplementation, for example, it will take longer before the short-term energy source is depleted and a switchover to slower carbohydrate or fat metabolism is needed.

This process can be visualized as if you have a large wad of cash (i.e., creatine-phosphate) in your wallet. It's there, ready to meet your immediate needs. The more you supplement this wad, the more energy purchases you can quickly make. In contrast, generating your energy through carbohydrate or fat metabolism is the equivalent of writing a check that must clear the system, a more time-consuming process better suited to meet your long-term, larger needs.

Strength and Muscles

Creatine supplementation is most useful for physical activities that require intense bursts of energy--e.g., a bench press, sprint, or games requiring energy bursts. It is less useful for endurance events, except when such events are enhanced by building up muscle strength through creatine-stimulated weightlifting.

Creatine can build muscle mass by several mechanisms. For example, weightlifting is exactly the sort of short-term, intense physical activity fostered by creatine; more repetitions and harder workouts can be achieved, building up muscle. However, creatine increases water uptake into the muscle, a process called cell volumizing that bulks up the muscles in a fashion that may not add much real strength.

Supplementation Cycle

In one commonly used, creatine-supplementation cycle, four 5-gram doses of creatine are consumed daily for five days. These are often dissolved in a sweetened solution to enhance uptake. After this loading phase, the daily dose is reduced to two grams for a month, after which supplementation is discontinued for an additional month. The cycle then starts over.

The washout period is recommended because increased creatine levels will eventually trigger the body to shut down its creatine production and transport into muscle from the blood. After the washout period, the body regains these functions. Although some physical gains may be lost, because more intense workouts were achieved during the earlier supplementation phase, the next cycle will start at a higher baseline.

Side Effects

In addition to potential transient gastrointestinal disturbances, chronic creatine supplementation may stress kidneys and increase exposure to potential, manufacturing-process contaminants. Although risk appears low given its extensive history of use, normal metabolic patterns are affected to obtain the desired benefits, which over time may have yet undefined deleterious effects.

Physical Disability

Studies suggest that creatine can enhance strength compromised by physical disability. For example, investigators at the Miami Project have shown that creatine promotes upper-extremity work capacity in quadriplegics (Jacobs, et al, Arch Phys Med Rehabil, 83, January 2002, pp. 18-23).

In this study, 16 male quadriplegics with complete C5-7 injuries were randomly assigned to receive 20 grams/day of creatine or placebo maltodextrin (a common food ingredient) for seven days. Treatment was then discontinued for a three-week washout period, after which the treatment groups were reversed for another seven days--i.e., the initial placebo group now received creatine, and the initial creatine group was given maltodextrin.

Work capacity was assessed before and after each dosing period using arm ergometry, a common SCI rehabilitation exercise. Specifically, subjects faced a series of two-minute, increasing-intensity work stages with one-minute, intervening recovery periods.

After creatine supplementation, improvements were noted in various respiratory measurements, including oxygen uptake, carbon dioxide production, tidal volume (amount of air that enters the lungs), and breathing rate. For example, 14 of the 16 subjects demonstrated increased oxygen uptake, averaging an impressive 18.6%. Improvements were also noted in peak power output and increased time to fatigue.

In another example, Drs. Stephen Bums and Richard Kendall, University of Washington, evaluated the effects of creatine supplementation on arm strength in C6 quadriplegics using a similar study design as before (personal communication). In this study, however, preliminary analyses indicated no major benefits. Dr. Bums speculates that creatine supplementation provides to SCI and neurologically intact individuals similar modest benefits in response to repeated maximal efforts on short-duration exercises. However, these benefits may be offset by weight gain attributed to nonstrength-associated water uptake. In other words, you may be hauling around more weight that will enhance neither sporting nor transfer ability.

In a final example, investigators have shown that creatine can increase handgrip, knee-extension, and ankle strength in people with various forms of neuromuscular disease (Tarnopolsky, M. & Martin, J., Neurology, 52, 1999, pp. 854-7).

The differences in the indicated benefits between studies are not surprising because results can be affected by many interacting factors, including (in these cases) the selected outcome measures, dosing regimens, and sample sizes (e.g., more subjects may statistically demonstrate subtler effects).

In conclusion, although more definitive studies are needed, creatine's potential benefits have important ramifications for many people with physical disabilities because the enhancement of residual strength, even to a limited degree, often can have profound quality-of-life implications.

Resources

An excellent review of creatine studies has been posted on http://carecure .rutgers.edu (click on CareCure Community and scroll down to the creatine article).

The author invites the comments of readers who have had experience with creatine supplementation (laurancejohnsto@aol.com).

Information for this column is provided by S. Laurance Johnston, Ph.D., laurancejohnsto @aol.com.

The thoughts expressed here are solely those of the author and are not necessarily those of PN/Paraplegia News or the Paralyzed Veterans of America. Readers should thoroughly investigate alternative treatments before practicing them.

Information for this column is provided by S. Laurance Johnston, Ph.D., laurancejohsto@aol.com
COPYRIGHT 2002 Paralyzed Veterans of America
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2002 Gale, Cengage Learning. All rights reserved.

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Author:Johnston, S. Laurance
Publication:PN - Paraplegia News
Geographic Code:1USA
Date:Nov 1, 2002
Words:1246
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