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Optimizing Around Workout Nutrition

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Apr 2, 2009
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BY: Lyle McDonald

Tang JE et. al. Minimal whey protein with carbohydrate stimulates muscle protein synthesis following resistance exercise in trained young men.
Appl Physiol Nutr Metab. 2007 Dec;32(6):1132-1138.

Whey protein is a supplemental protein source often used by athletes, particularly those aiming to gain muscle mass; however, direct evidence for its efficacy in stimulating muscle protein synthesis (MPS) is lacking. We aimed to determine the impact of consuming whey protein on skeletal muscle protein turnover in the post-exercise period. Eight healthy resistance-trained young men (age = 21 +/- 1 .0 years; BMI = 26.8 +/- 0.9 kg/m2 (means +/- SE)) participated in a double-blind randomized crossover trial in which they performed a unilateral leg resistance exercise workout (EX: 4 sets of knee extensions and 4 sets of leg press; 8-10 repetitions/set; 80% of maximal), such that one leg was not exercised and acted as a rested (RE) comparator. After exercise, subjects consumed either an isoenergetic whey protein plus carbohydrate beverage (WHEY: 10 g protein and 21 g fructose) or a carbohydrate-only beverage (CHO: 21 g fructose and 10 g maltodextran). Subjects received pulse-tracer injections of l-[ring-2H5]phenylalanine and l-[15N]phenylalanine to measure MPS. Exercise stimulated a rise in MPS in the WHEY-EX and CHO-EX legs, which were greater than MPS in the WHEY-RE leg and the CHO-RE leg (all p < 0.05), respectively. The rate of MPS in the WHEY-EX leg was greater than in the CHO-EX leg (p < 0.001). We conclude that a small dose (10 g) of whey protein with carbohydrate (21 g) can stimulate a rise in MPS after resistance exercise in trained young men that would be supportive of a positive net protein balance, which, over time, would lead to hypertrophy.

Lyle Comments: Optimizing around workout nutrition is currently a major area of research interest and a topic that I discuss for 30 pages in the Protein Book. As discussed there, early guidelines were primarily aimed at maximizing muscle glycogen storage, usually following endurance training although more recent work has focused on promoting muscle gains following resistance training. Similarly, while early work focused almost entirely on carbohydrate intake, more recent studies have begun to examine the impact of dietary protein either alone or in combination with carbohydrate.

Nutrient intake around training (and this includes before, during and after) can potentially impact on both protein synthesis and breakdown and, in general, it's been found that protein/amino acids have the greatest effect on protein synthesis (with minimal impact on protein breakdown) while changes in insulin concentrations have their primary impact on protein breakdown (with minimal impact on protein synthesis). A number of studies suggest that the combination of increases blood amino acid levels with increased insulin has the greatest impact on net protein gain (which is the net effect of protein synthesis minus protein breakdown).

Previous studies have used various combinations and amounts of different types of proteins and carbohydrates. Whey, casein and essential amino acids have all been studied along with protein/amino acid blends. Carbohydrate type has been less systematically studied with sucrose (table sugar) and dextrose having been the primary types used.

This week's study used a combination of a small amount of whey protein (chosen for its rapid digestion time, an effect that may not actually be optimal following training as I discuss in the Protein book) with fructose. The latter was chosen over more insulin stimulating carbohydrates based on the idea that large increases in insulin following training may blunt fat oxidation, an effect that is not desired by individuals trying to reduce fat mass. I'd point out that other research suggests that the body continues using fat for fuel following training even when insulin is raised, so this may not be a valid concern. A study I reviewed in a previous newsletter by Cribb actually reported a small fat loss despite dextrose being given with protein before and after training.

In any case, the study recruited 8 resistance trained males who had been lifting consistently for the previous 12 months minimum, most reported nearly 6 years of having lifting weights so they weren't the typical untrained subjects.

The subjects performed 2 separate trials separated by 2 weeks, since the resistance training was a leg workout, they avoided training legs for at least 4 days prior to each trial.

The workout consisted of 1-legged leg extensions and 1 leg leg presses for 4 sets of 8-10 reps at 80% of their single leg 1 repetition maximum, 2 minutes rest was taken between sets. Only one leg was trained so that the rested leg could act as a control for measurement of protein synthesis. Following training subjects either received 10 grams of whey protein with 21 grams of fructose or 21 grams of fructose with 10 grams of maltodextrin. A variety of measures including protein synthesis, blood glucose, insulin, branched chain, essential and total amino acid levels were all measured.

Not surprisingly, given the maltodextrin intake, blood glucose rose significantly higher in the carbohydrate only drink compared to the whey/fructose drink. Blood glucose levels were almost unchanged in the whey/fructose drink.

Blood insulin increased with both drinks although it was higher in the carbohydrate only drink. Often forgotten is that the branched chain amino acids raise insulin which is what most likely accounted for this response.

As would be expected, branched chain, essential and total amino acids only increased following the whey/fructose drink. Blood amino acid levels peaked at the one hour mark and were back to normal by 3 hours following consumption of the drink. As well, blood amino acid levels actually went down slightly in the carbohydrate only drink. This isn't a surprising observation and previous work has actually shown that raising insulin without increasing blood amino acids can lower protein synthesis by lowering the availability of amino acids in the bloodstream.

Finally, looking at protein synthesis, while both the carbohydrate and whey/fructose drink increased the fractional synthetic rate of protein in the exercised leg, the whey/fructose drink had a greater overall impact, consistent with previous work on the topic.

So what does this study tell us? First and foremost, as is consistent with endless previous data, protein plus carbohydrates is superior to carbohydrate alone following resistance training. It would have been nice if the study had included a protein only group but, for the most part, studies have found that protein plus carbs is still overall superior to protein alone. Again, this topic is discussed at length in Chapter 8 of the Protein Book.

I'd note that the amount of protein used, 10 grams of whey, providing roughly 4 grams of essential amino acids is below the amount thought to be required to maximize protein synthesis following training.

As well, it's possible, given previous work looking at sucrose or dextrose, that a more insulinogenic carbohydrate would have provided a larger response.

However, not everyone who lifts weights is looking for a maximal or optimal protein synthetic response following training, not everybody is trying to get super-jacked and massive. If nothing else this study suggests that smaller amounts of nutrients following training (meaning a smaller caloric intake overall, potentially beneficial for athletes trying to reduce body fat) can be effective at promoting adaptations following training. Smaller athletes (females or smaller males) who have smaller caloric requirements may be able to reduce their caloric intake around training while still promoting positive benefits.

And while I generally feel that cutting calories around training while dieting is a mistake (I'd rather see calories cut at other meals of the day), this study would suggest that smaller amounts of nutrients around training can still be effective, allowing more calories to be consumed at other times of the day