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Een deel van de tekst die rond 2001 door Bioenergy(.com) werd uitgeleend om de theorie achter het gebruik (en de verkoop) van d-ribose te versterken, maar alleen wat opgepoetst er nog is te vinden: Ribose Effects in Skeletal Muscle Several studies have noted that while healthy skeletal muscle has a large capacity for high-energy phosphate turnover, intense exercise causes significant decreases in ATP and total adenine nucleotides (TAN) pools. One study showed that one week of high-intensity exercise significantly decreased levels of both ATP and TANs in skeletal muscle with no meaningful recovery even after 72 hours of rest. This decrease in ATP (23%) and TAN (24%) is reflective of the loss of nucleotides from muscle during and following high intensity exercise. Furthermore, the delayed recovery of ATP and TANs is likely explained by the lack of the availability of 5-phosphoribosyl-1-pyrophosphate (PRPP), the rate-limiting factor in adenine nucleotide synthesis and salvage. A second study found that resting ATP and TAN levels were lowered by 19% and 18% respectively after high intensity exercise training. These lowered levels were primarily attributed to an inability of skeletal muscle to completely restore the purines that were lost as a result of high ATP turnover during training periods. Total purines continue to decline in the first few minutes following exhaustive cycle exercise as found in a study of 8 healthy male subjects. An average decrease of 6.3% in total purines was seen between the time the exercise period ended and 3 minutes into recovery. This provides evidence that there are rapid changes in TAN levels due to degradation and purine efflux. In two benchmark studies ribose administered to isolated hind limb muscle fibers in vitro led to increased adenine nucleotide de novo synthesis rates of 3.4 to 4.3-fold and adenine and hypoxanthine salvage rates of 3 to 6-fold. Fast-twitch red gastrocnemius, fast-twitch white gastrocnemius, fast- twitch mixed plantaris, and slow-twitch red soleus muscle fiber types were studied. The greatest increase in both de novo synthesis and adenine and hypoxanthine salvage rates were seen in the low-oxidative fast-twitch white gastrocnemius muscle, with significant increases in the other muscle types as well. The importance of ribose in skeletal muscle energy metabolism was noted, and its impact on PRPP availability thought to be most critical. Figure 4 The mean power output per kilogram body weight for athletes consuming ribose supplement or glucose placebo. For each group n = 8. Figure 5. Percent fatigue in athletes consuming ribose supplement or glucose placebo. For each group n = 8. Another aspect of the same study showed that ribose supplementation partially attenuated the decrease in TAN levels after the 5 days of exercise (p < 0.05). While the placebo and ribose groups displayed a similar pattern of recovery of TAN levels, the ribose group recovered to pre-exercise levels after the 65 hour recovery period, but the placebo group remained at 23% below pre-exercise levels (Figure 6). Figure 6. Total adenine nucleotide levels from muscle biopsies in athletes consuming ribose supplement or glucose placebo. For each group n = 8. The fact that ATP and TAN levels decrease during exercise and normally do not recover even after three days of rest indicates that without supplementation skeletal muscle has a limited ability to maintain peak performance during periods of repeated high-intensity exercise. However, the studies reviewed here indicate that the administration of ribose leads to an increase in the power output in athletes and improves the ability of skeletal muscles to quickly recover their energy levels after high intensity exercise. Indeed a study of exercise performance over 4 weeks in male bodybuilders showed a significant increase in the number of total repetitions performed in bench press exercises in athletes taking ribose compared to athletes taking glucose placebo. The subjects were randomly divided into two groups, 5 subjects consuming ribose and 7 subjects consuming glucose placebo. The supplements were taken in divided doses, 5 grams 15 minutes prior to exercise and another 5 grams immediately post-exercise. The ribose group experienced a significant increase in the number of bench press repetitions performed to muscular failure (+29.8% ribose vs. +7.42% placebo, p = 0.046 placebo n = 7, ribose n = 5). Witter, J., P. Gallagher, D. Williamson, M. Godard, and S. Trappe. Effects of ribose supplementation on performance during repeated high-intensity cycle sprints. Midwest Regional Chapter of the ACSM, October 2000. Gallagher, P.M., D.L. Williamson, M.P. Godard, J. Witter, S.W. Trappe. Effects of ribose supplementation on adenine nucleotide concentration in skeletal muscle following high-intensity exercise. Midwest Regional Chapter of the ACSM, October 2000. Antonio, J. D. Van Gammeren, and D. Falk. The effects of ribose supplementation of exercise performance in recreational male bodybuilders. Data on file at Bioenergy, Inc., 13840 Johnson Street N.E., Ham Lake, Minnesota 55304 USA © 2001 Bioenergy (.com) |