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Protein: The Most Important Nutrient

In perhaps a more intriguing study, scientists looked at the effects of a high-protein vs. a high-carbohydrate diet on performance during an ultraendurance climbing race at moderate altitude.

Have you ever wondered why traditional nutritionists can’t say the word carbohydrate fast enough when asked what foods athletes should eat more of when their training volume and/or intensity goes up? Why the F is that? Is the concentration of glycogen in skeletal muscles really a limiting factor in building muscle? Doubt it. Then why the eat-more-carbs mantra? Because they’re just not that smart, or they just don’t like to read that boring stuff we call science.

To wit: We know that protein hydrolysates can speed tissue repair following exercise-induced damage, which may be good for accelerating recovery. The potential for a hydrolysate of whey protein isolate to speed recovery following eccentric exercise was evaluated in a recent study. In a double-blind, randomized parallel trial, 28 sedentary males underwent 100 maximal eccentric contractions—a.k.a. negatives—of their knee extensors. They then drank 250 milliliters of 1) flavored water, 2) flavored water containing 25 grams of whey protein isolate or 3) flavored water containing 25 grams of whey. The whey protein hydrolysate proved to be the best for helping athletes recover from fatiguing eccentric exercise.1 Pretty cool. So not all whey protein is created equally.

In perhaps a more intriguing study, scientists looked at the effects of a high-protein vs. a high-carbohydrate diet on performance during an ultraendurance climbing race at moderate altitude.

On two different occasions, 10 climbers, 30 years old on average, participated in the race, which lasted approximately 29 hours. They were fed 4,000 calories daily, getting either 30 percent of them as protein or 68 percent as carbohydrate. The researchers tested the subjects for mental performance and quadriceps strength.

Mental performance was unaffected after the two races, while muscular performance and bodyweight dropped, with no differences between the diet groups. The researchers noted decreases in IGF-I concentration and its binding protein IGFBP-3 and increases in cortisol and norepinephrine, with no diet effects again. Glucose concentration decreased without diet effects, while the amino acids leucine, isoleucine, valine and tyrosine decreased in the higher-carb group only. Thus, the study showed that a high-protein or high-carb intake during physical exertion at a moderate altitude maintained mental performance but did not limit muscle force reduction or bodyweight loss.2

What’s the significance? It shows that carbohydrate isn’t better than protein for your diet. Indeed, the fact that there were no differences in any of the major measures shows clearly that you may be better off favoring protein than carbs. For one thing, protein plays myriad roles in your body, more than carbs. Here’s a sports analogy: Which position in football is more important, the quarterback or the left guard? Exactly. Protein is the quarterback of food. Eat it, love it, and get plenty of it!

Editor’s note: Jose Antonio, Ph.D., is the CEO of the International Society of Sports Nutrition (; also check out his site


1 Buckley, J.D., et al. (2008). Supplementation with a whey protein hydrolysate enhances recovery of muscle force-generating capacity following eccentric exercise. J Sci Med Sport. 13:178-81.

2 Bourrilhon, C., et al. (2009). Influence of protein- versus carbohydrate-enriched feedings on physiological responses during an ultraendurance climbing race. Horm Metab Res. 42:31-7.

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