But recent research also indicates that the supply of actual ATP molecules is reduced during exercise, and can become a performance limiting factor, as well as increase the time of post-exercise energy recovery.
A new dietary supplement ingredient, ribose, claims to increase ATP and energy levels, based on scientific research. This article reviews some of the relevant studies and facts concerning ribose, its proven effects on human performance, and its potential use as an energy supplement. Ribose is used in the body as a precursor for making ATP molecules, also proteins, DNA, RNA, and other nucleotides.
Ribose can contribute to the pool of energy substrates, in particular through the conversion of pyruvate. Therefore, the primary benefit of taking ribose is to maintain and replenish ATP molecule levels in your body, and a secondary benefit of ribose is contributing directly to energy production as an energy substrate.
When you exercise, some of the ATP that your body uses for energy is lost from your cells and must be replaced. Ribose is the only compound the body uses as a starting point to replace these energy-producing molecules. However, ribose production in the heart and skeletal muscles is a slow process, and cannot always keep up with the loss of energy during ischemia (insufficient blood flow) or strenuous, intensive exercise. Under normal conditions, it may take several days to completely restore ATP molecules that are lost due to disease-caused ischemia, or from intensive exercise.
Ribose is produced in the body from glucose. But as with other metabolites, like L-carnitine and creatine, ingesting ribose it can bypass the body's slow production pathways, and result in production of ATP molecules at a higher then normal rate. When scientists examined ribose ingestion with animals and people, their results indicate that ribose can be directly used to rebuild the energy-producing molecules as they are used up by the cells. As a result, your body can quickly rebuild its ATP supply, making it available for maximum performance.
Although heart and muscle cells have the ability for forming, recycling, and conserving energy-producing molecules, they are not always successful at keeping up sufficient levels of ATP. Both intensive exercise and ischemia can cause significant losses of ATP, leaving the cells wanting for energy. When this happens, the functioning of the cells may be compromised. If you are a strength athlete, you may not be able to generate the powerful contractions you need to lift your barbell, and the weight you lifted only a day or two ago may be impossible to move today. Your heart may not pump enough blood to supply your tissues with adequate amounts of oxygen.
Reduced ATP levels will also reduce performance in the endurance athlete and fitness exercisers. Research has shown that decreases in ATP can be as much as 37% percent after periods of high-intensity exercise. Both the fast-twitch and slow-twitch muscle fibers use ATP for energy to contract. So the amount of ATP molecules depleted during exercise can be significant. Studies also show that when cells lose their ATP during exercise, it may take three days of rest, or more to fully replenish ATP muscle and heart tissue levels.
A Quick Review Of The Research On Ribose
Like with other developments in sports nutrition, the story of ribose began from its use in animal research and medicine. In 1983, H.G. Zimmer looked at the effects of ribose administration to rats with reduced heart function due to poor blood supply and reductions in adenosine triphosphate and total adenine nucleotide tissue levels. After 24 hours of ribose administration, biosynthesis of cardiac adenine nucleotides was stimulated and ATP levels were improved. This resulted in improved heart function of the research animals.
In 1984, H. G. Zimmer reported again that administration of ribose, via i.v. infusion, lead to restoration of cardiac ATP levels within 12 hours, during recovery from a 15-minute period of myocardial ischemia. This was compared to taking 72 hours for ATP normalization in animals without the benefit of ribose administration. To further this research, after concluding that ribose is cardioprotective in the rat and stimulates the production of ATP and other adenine nucleotides, H.G. Zimmer's attention was turned to verifying these effects in other animals. In the 1984 February issue of Science, H. G. Zimmer reported that ribose had a similar myocardial ATP stimulating effect in other animal species.
In 1987 John St. Cyr and coworkers reported the results of using ribose on dogs. They found that ATP levels dropped significantly following global ischemia in dogs, and required several days to fully recover. They found that after ribose administration ATP levels rebounded significantly within 24 hours. They concluded that ribose infusion significantly enhanced the recovery of energy levels in the postischemic myocardium in the experimental dogs.
Similar to the experimental animals, researchers found comparable results when examining ATP dynamics in human subjects. In 1986 M. E. Cheetham reported that after 30 seconds of maximal sprinting, upon biopsy examination, female subjects had decreased muscle glycogen, phosphocreatine, and ATP levels. N. McCarthy reported similar findings based on research using male human subjects. After performing four 30 second bouts of maximal isokinetic cycling at 100 rpm, with 4 minute recovery intervals, ATP, glycogen and phosphocreatine muscle tissue levels were greatly reduced. More recently in 1993, Y. Hellsten-Westing, et al., reported that in human male subjects, intermittent exercise caused a reduction in ATP tissue levels.
So, ATP tissue levels can be reduced from poor blood flow, or from exercise. The next step in ribose research lead to examine what happens to patients with medical conditions that cause ATP tissue depletion, when given ribose. M. Grose and coworkers investigated what giving ribose, orally or intravenously, did to healthy volunteers and patients with myoadenylate deaminase deficiency. Both groups well tolerated ribose administration. Although, no ATP tissues levels or exercise performance parameters were measured, this study was a stepping stone to demonstrating the ribose dynamics in human studies.
The researchers did observe a reduction in serum glucose levels during ribose administration, though, ribose administration was well tolerated. In 1991 D. R. Wagner and coworkers looked at the effects of oral ribose administration of three patients with AMP deaminase deficiency. Three grams of ribose was given to subjects orally, every 10 minutes, beginning 1 hour before exercise until the end of the exercise periods. Exercise was performed on a bicycle ergometer. The researchers found that ribose administration did not improve maximum exercise capacity in these three patients, but found that postexercise muscle stiffness and cramps disappeared almost completely in 2 of the 3 patients tested.
They concluded that ribose may both serve as an energy source and enhance the synthesis of ATP. Two key studies have verified the safety and effectiveness of ribose in human subjects. In 1986, N. Zollner found that taking D-ribose improved tolerance to exercise in a 55 year old patient suffering from exercise-induced muscle pain and stiffness, due to primary myoadenylate deaminase deficiency. The patient was taking 4 grams of D-ribose before exercising to prevent the symptoms, during a two year period.
This dosage had to be taken every 10 to 30 minutes of exercise, with a total dose of 50 to 60 grams per day, being well tolerated without side-effects. In 1992, W. Pliml and coworkers reported the results of their research on the effects of ribose on exercise-induced ischaemia in stable coronary artery disease, in the Lancet. They were trying to develop a strategy aimed at protecting or restoring cardiac energy metabolism, which was greatly impaired by ischaemia. The existing scientific evidence that ribose stimulates ATP synthesis and improves cardiac function led them to test the notion that ribose increases tolerance to myocardial ischaemia in male patients with documented severe coronary artery disease.
The researchers selected male subjects to take 60 grams of D-ribose daily divided in four dosages per day, for 3 days, or a placebo. They found that the ribose taking group better tolerated treadmill walking exercise, which improved the heart's tolerance to exercise induced ischaemia.
The Million Dollar Question
Does ribose supplementation increase exercise or athletic performance? The answer is maybe. In fact, the company that makes RiboCell, a D-ribose raw materials sold to supplement companies, Nutratech, has a study underway to examine the performance and recovery effects of taking D-ribose in athletes. No one can say, however, that taking ribose will definitely make you feel more energetic. Nor can anyone say that your athletic performance will improve. The scientific evidence is clear, however, that ribose will help your heart and skeletal-muscle cells maintain their energy charge and normal function, and that taking ribose before, during, and after periods of high-intensity exercise will increase your exercise effectiveness.
The research does show that for individuals with heart and circulatory system problems, ribose can in some instances help increase exercise performance and tolerance. Ribose supplement use may also help the beginner exerciser. Ribose may also have beneficial effects for serious competitors or a hard-charging weekend athletes. Athletes' hearts and skeletal muscles use energy faster than it can be replaced. Ribose is effective at rebuilding these critical energy stores to keep the heart and skeletal muscles at their peak. Taking ribose containing drinks, before, during and after exercise may be worth a try for these exercising individuals.
Research has shown that about 3 to 5 grams of ribose taken every day should put enough in the bloodstream to ensure that the heart and skeletal-muscle cells have an adequate supply. Serious athletes and people concerned about their circulation may want to take more. In fact, these people may require 10 to 20 grams or more per day.
A good course of action would be to start out with about 5 grams of ribose per day. If you feel you need more, increase your dosage by about 3 to 5 grams per day. However, do not take more than 15 to 20 grams per day. For people with heart or circulatory system problems, who want to try using ribose to increase exercise tolerance or reduce post-exercise soreness or stiffness, they should do so under doctor supervision.
Safety Of Ribose
Scientific research with ribose has been going over the past two decades and in some of these studies, very high doses of ribose were administered. In one study with patients with severe coronary artery disease doses of 60 grams per day for three days were used. In these patients, there were no lasting side effects. In still another study, ribose was given in 60-gram doses for seven days to patients. Some of the patients taking these very high doses developed minor cases of diarrhea, while others had occasional mild and asymptomatic hypoglycemia. It should be noted that these studies were only a few days long.
The study mentioned above with the 55 year old using ribose, was over a year period, but under doctor supervision. Ribose is currently sold as a dietary supplement. It is best to follow the directions that come with the specific product, keeping the reports of the studies reviewed in this article in mind, as to not over-do-it. At this time there is a lack of scientific evidence to state with certainty that ribose is safe for long-term use, by all people. Its use should therefore be restricted to adults, and for short-term periods. Discontinue use if any side effects occur. It is always best to consult your physician before taking newly developed supplement product, or if a disease condition exists.
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Cheetham, et al. "Human muscle metabolism during sprint running." J. Appl. Physiol. 61 (1986): 54-60.
Gross, M. et al. "Metabolism of D-ribose administered continuously to healthy persons and to patients with myoadenylate deaminase deficiency." Klin. Wochenschr. 67(1989): 1205-1213.
McCartney, N., et al. "Muscle power and metabolism in maximal intermittent exercise." J. Appl. Physiol. 60 (1986): 1164-1169.
Pliml, W., et al. "Effects of ribose on exercise-induced ischaemia in stable coronary artery disease." The Lancet Vol. 340 (1992): 507-510.
St. Cyr, J. A, et al. "Enhanced high energy phosphate recovery with ribose infusion after global myocardial ischemia in a canine model." J. Surgical Res. 46 (1989): 157-162.
Tullson, P and R. Terjung. "Adenine nucleotide synthesis in exercising and endurance-trainined skeletal muscle." Am. J. Physiol. 261 (1991): C342-C347.
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Zimmer, H.G., et al. "Ribose intervention in the cardiac pentose phosphate pathway is not species-specific." Science 223 (1984): 712-714.
Zimmer, H.G., and H. Ibel. " Ribose accelerates the repletion of the ATP pool during recovery from reversible ischemia of the rat myocardium." J. Mol. Cell. Cardiol. 16 (1984): 863-866.
Zollner, N., et al. "Mooadenylate deaminase deficiency: successful symptomatic theraphy by high dose oral administration of ribose." Klin. Wochenschr. 64 (1986): 1281-1290.