Healthier Life: Protein Requirements for Strength Training

KIRTLAND AIR FORCE BASE, N.M. -- Though a well-designed resistance training program is at the core of building muscle, protein consumption also has an important role to play. There is, unfortunately, a lot of bad science on the Internet regarding protein and strength training, and a lot of misconceptions have become “fact” as a result.

There is a balancing act in skeletal muscle between creation of new muscle proteins (protein synthesis) and breakdown of old ones (protein breakdown.) For increases in muscle size to occur, protein synthesis must exceed protein breakdown. A single bout of resistance training will increase protein synthesis by > 100%. However, protein breakdown is also increased by resistance training. This is where dietary protein becomes important, as protein can elevate protein synthesis consistently above protein breakdown. Over time, this will result in increases in muscle fiber diameter, otherwise known as hypertrophy. 

How much protein is required to maximize muscle growth? A recent review of protein supplementation and muscle mass concluded that intakes of 1.6 grams per kilogram body mass, up to perhaps 2.2 grams provides the maximum benefit. If one is trying to reduce body fat, and retain lean mass, higher intakes, 2.4 - 3.1 grams of protein per kilogram body mass are likely needed. Here’s how to calculate individual protein needs. First, divide body weight in pounds by 2.2 to obtain kilograms. If I use a 150-pound subject as an example, this calculates as 150/2.2 = 68.2 kilograms. Next, I multiply 2.2 x 1.6, which = 109 grams. If one has four meals per day 109/4 = 27.2 grams of protein per meal.

Maximum rates of protein synthesis top out at 20-30 grams of protein per meal in young (< 30 years of age) adults. Protein consumed in larger quantities doesn’t appear to have any benefit. One exception to this is older (> 60 years of age) adults. Older adults are not as efficient in converting dietary protein to muscle protein. As a result, older adults need more protein (30-45 grams per meal) to enhance protein synthesis. We don’t have good data for adults 30-60 years in age, so we don’t know at what age this decrease in efficiency starts.

Differences in protein quality also affect muscle protein synthesis. Animal proteins (milk, eggs, meat) have higher quality scores than plant proteins, so one does not have to eat as much of these relative to plant proteins to see increases in protein synthesis. For example, consumption of 35 grams of whey protein (the liquid part of cottage cheese), casein protein (the white solids in cottage cheese) and wheat protein found that whey > casein > wheat for increasing muscle protein synthesis. Raising the amount of wheat protein to 60 grams did increase protein synthesis to levels comparable to casein. This doesn’t mean vegetarians can’t increase muscle size/strength; they certainly can, though consulting with a registered dietitian is recommended. A related myth is egg whites are better than whole eggs for muscle growth; the opposite is true, so there is no need to throw the yolk away. One food you don’t want to consume after exercise is alcohol. Multiple studies show alcohol impairs protein synthesis following a bout of exercise.

Does protein timing matter? The research to date indicates that timing doesn’t appear to matter all that much. For example, one study found no differences in muscle hypertrophy or body composition whether subjects consumed protein immediately prior to or after a workout. Another study concluded casein supplements consumed in the morning had the same effect on muscle size/strength as the same supplement consumed shortly before bed. 

For more information on how to improve your workouts, contact Health Promotion Flight at 846-1186 or 846-1483. We’re also now on Facebook; type “KAFB Health Promotion” into the Facebook search box to find our group page. Anyone who is affiliated with Team Kirtland is welcome to join!

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