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Old 03-23-2007, 06:15 PM
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Default Re: Pre Workout Carbohydrate Consumption

Martin,

It sounds like you are a scientist! I think it is fantastic that you are interested in this topic. Again, the best advice I can give is to read the article I gave, and do a search in the journal of strength and conditioning research. You will literally find endless research on this topic. Here is a sample quote supporting my comments. For many more, again, refer to the sources I have indicated here.

[ QUOTE ]
Traditionally, it has been thought that short-duration high-intensity exercise is primarily supplied with energy from the muscular stores of phosphagens (adenosine-triphosphate phosphocreatine system), with glycogenolysis and glycolysis supplying minimal amounts of energy (55). Recently, glycogenolysis has been demonstrated to be an important energy supplier during high-intensity intermittent exercises, such as resistance training (54, 67, 72, 73). Recently, Haff et al. (26) reported that 3 sets of isokinetic leg extensions performed at 120s1 can reduce the muscle glycogen content of the vastus lateralis by 17%. Additionally, in the same investigation a multiple-set resistance-training session (back squats, speed squats, 1-leg squats) performed at 65, 45, and 10% of 1 repetition maximum (1RM) back squat resulted in a 26.7% decrease in muscle glycogen of the vastus lateralis. Tesch et al. (73) have also reported a 40% reduction in muscle glycogen in response to the performance of 5 sets of 10 repetitions of concentric knee extensions performed at 60% of 1RM. A 30% decrease in the muscle glycogen content of type IIab and IIb fibers in response to this protocol was also reported (73). Muscle glycogen concentration was also reported to decrease by 20% in response to the performance of 5 sets of 10 repetitions at 45% of 1RM. Similarly, Robergs et al. (67) have shown that 6 sets of 6 repetitions of leg extensions performed at 70 and 35% of 1RM can elicit a significant glycogenolytic effect resulting in 39 and 38% reductions in glycogen, respectively. Type II fibers were also demonstrated to have a greater glycogen loss when compared with type I fibers (67). Tesch et al. (72) also reported that a 26% decrease in the muscle glycogen content of the vastus lateralis can occur in response to a resistance-training regimen consisting of 5 sets of front squats, back squats, leg presses, and knee extensions. One set of 10 repetitions of biceps curls can also reduce muscle glycogen by 13%, whereas 3 sets of 10 can result in a 25% reduction in muscle glycogen (54). Pascoe et al. (65) have reported a 31% reduction in muscle glycogen content in response to leg extensions performed to muscular failure (sets: 8.0 0.7). The results of these studies indicate that muscle glycogen is an important fuel source during resistance training and suggest that glycogen depletion is dependent upon the total amount of work accomplished.

Resistance-training sessions that center on higher repetition schemes (812 repetitions) and moderate loads such as those utilized during the hypertrophy phase of many athletes and bodybuilders may have a greater effect on muscle glycogen concentration than those of lower repetition schemes. However, very little research has been conducted examining the glycogenolytic effect of low-volume, heavy-load resistance-training protocols. Typical high-volume resistance training, which involves moderate to heavy loads, seems to preferentially deplete type II fibers. Because type II fibers usually express higher glycolytic enzyme activity than do type I fibers, a preferential depletion of muscle glycogen may not be totally unexpected (23). The preferential depletion of type II fibers during high-intensity exercise (24, 78), such as resistance training, may compromise the performance of high-intensity exercise and ultimately lead to a decrease in performance.

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G. GREGORY HAFF, MARK J. LEHMKUHL, LORA B. McCOY and MICHAEL H. STONE. 2003: Carbohydrate Supplementation and Resistance Training. The Journal of Strength and Conditioning Research: Vol. 17, No. 1, pp. 187196.
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Gabriel "Venom" Wilson, Ph.D. Nutritional Sciences
B.S. (Hons) & M.S. in Kinesiology, CSCS
Vice President, ABCbodybuilding
Co-Editor. of JHR

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