The general concensus here seems to now be that the carbs are best in the POST wkout shake, and that a SEPERATE shake be used for DURING. (IE: amino blend w/out carbs)
Studies show that CHO feedings during prolonged exercise can delay fatigue. I realize not all of the following studies involve weightlifting but I believe they still hold merit.
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When subjects consumed the CHO solution, fatigue was delayed by ~1 h.
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"...CHO-E ingestion improves endurance capacity during intermittent high-intensity running..."
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"These findings indicate that an increase in dietary CHO content... allowed better maintenance of physical performance and mood state over the course of training"
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"CHO ingestion resulted in a 37% longer run time to fatigue and faster 20-m sprint time during QTR-4"
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"Plasma glucose and insulin were higher, RPE for the legs was lower, and time to fatigue was longer in CHO than P."
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"Subjects ran longer when fed either CHO or CHO+BCAA as compared to P, with no differences between CHO and CHO+BCAA."
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"These results suggest that CHO supplementation can enhance prolonged continuous variable-intensity exercise by reducing dependency on muscle glycogen as a fuel source."
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"CHO-E offers potential to enhance exercise capacity by elevating blood glucose and thereby preventing hypoglycemia, maintaining high rates of carbohydrate oxidation, and/or preventing central fatigue"
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"The data prove that CHO intake may facilitate the maintenance of physical quality during long-lasting intermittent exercise to fatigue."
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"A carbohydrate beverage with additional protein calories produced significant improvements in time to fatigue and reductions in muscle damage in endurance athletes. Further research is necessary to determine whether these effects were the result of higher total caloric content of the CHO+P beverage or due to specific protein-mediated mechanisms."
for good measure...
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"These results suggest the use of a CHO-PRO supplement during resistance training to reduce muscle damage and soreness."
and a good one on taurine...
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"These results indicate taurine treatment is useful for reducing physical fatigue and muscle damage during exercise training in rats, presumably due to antioxidant property and improvement of muscle and cardiac functions by taurine."