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This is a pretty neat study as it shows increases in the stuff we’re interested in. Postwork nutrition studies, for example, have shown increases in protein synthesis and decreases in protein breakdown. This study shows that all that brings home the bacon.
Effects of leucine and whey protein supplementation during eight weeks of unilateral resistance training.
Coburn JW et al
The purpose of this study was to determine the effects of resistance training in combination with a leucine and whey protein supplement or a carbohydrate placebo on strength and muscle cross-sectional area (CSA). Thirty-three men (mean age +/- SD = 22.4 +/- 2.4 years) were assigned to 1 of 3 groups: (1) supplementation group (SUPP), (2) placebo group (PL), or (3) control group (CON). The SUPP and PL performed unilateral training of the leg extensor muscles with the nondominant limb for 8 weeks. The strength of each limb, muscle CSA of the quadriceps femoris (QF), and body composition were assessed pretraining and posttraining. The results indicated significant increases in strength for both limbs in the SUPP but only the trained limb in the PL. The increase in strength for the trained limb of the SUPP was greater than that for the trained limb of the PL. There was no significant increase in strength for either limb in the CON. There were significant increases in the CSA of all muscles of the QF of the trained limb for the SUPP and PL, and of the vastus lateralis of the untrained limb for the SUPP. The increases in QF CSA did not differ between the SUPP and PL. No significant CSA changes were found for either limb in the CON. There were no significant changes in body composition for the SUPP, PL, or CON. The current findings suggest that leucine and whey protein supplementation may provide an ergogenic effect which enhances the acquisition of strength beyond that achieved with resistance training and a carbohydrate placebo.
Interesting that it demonstrated strength increases but not CSA differences in the trained limb while there was a CSA difference in the untrained limb.
And that carbs alone were enough to increase CSA in the trained limb.
My initial comment comparing this study with PWO studies was a little off because the snazzy PWO combos that worked also contained carbs. However, given that the LEU/Whey group gave strength increases and the CARB group got CSA increases supports the idea of a PRO/CARB combo.
Should also make you think hard about unilateral training with the uninjured limb when one has an injury.
Food for thought!
Ok here’s my highly considered opinion on the findings.
Given that Leucine and whey will support plasma aminos and trigger protein synthesis, you would expect growth to occur wherever protein synthesis occurs i.e. all muscle. That was supported by these results. Would have been interesting to see if CSA was affected in other areas of the body.
Given that the carbs will cause an insulin spike and result in available nutrients being transported to particular cells that require them, you would expect a more site specific result. That was precisely what was recorded.
I think it lends great support to the current PWO nutrition theory.
Would also have been interesting to see if a combination of the SUPP and PL drinks outperformed the individual results.
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