Do endurance athletes really need more protein for muscle repair and recovery?
Posted Nov 05 2011 10:38am
“Athletes and exercising individuals need more protein.”
“Protein is crucial for muscle repair and recovery.”
“Eat more lean protein.”
Phrases such as this quite frequently get thrown around in sports and exercise nutrition geek-speak. Problem is, the importance of protein is blown way out of proportion (I personally plead guilty to having over-emphasized the importance of protein).
Sure, you certainly need the stuff. After all, when you eat protein, it gets broken down into protein building blocks called amino acids, and the amino acids are used for everything from cellular repair of all your damaged muscle fibers to a host of other metabolic reactions.
So to determine how much protein you actually should be getting, you need to be familiar with a term called “nitrogen balance”.
Here’s how nitrogen balance works:
Nitrogen enters your body when you consume protein from food or amino acid supplements , and nitrogen exits your body in your urine as ammonia, urea, and uric acid (all the breakdown products of protein) When the amount of protein you eat matches the amount of you use, you’re in nitrogen balance.
As you can probably deduce, if you don’t eat enough protein, you’ll be in negative nitrogen balance and quite unlikely to be able to repair muscle after a workout (a “catabolic” state), and if you consume too much protein, you’ll be in positive nitrogen balance, and while you’ll have what you need for muscle repair (an “anabolic” state), there can be some health issues that arise when you achieve too positive a state of nitrogen balance – since all that ammonia, urea and uric acid has side-effects (we’ll get into that in just a bit).
The current US recommended dietary allowance (RDA) is 0.36 grams of protein per pound of body weight per day (0.8g/kg), and was designed for most people to be in nitrogen balance – without protein deficits or protein excess. While athletes and frequently exercising individuals need more protein than this, you’ll frequently see bodybuilders, football players, weightlifters and other big strength and power athletes taking this to the extreme and consuming far in excess of this protein RDA (in some cases up to 2 grams per pound!)
But studies such as THIS one suggests that even for athletes, there really isn’t much additional benefit of exceeding 0.55 grams per pound of protein (1.2g/kg) if you want to maintain nitrogen balance. If you’re trying to exceed nitrogen balance for the purpose of putting on muscle, THIS study indicates that you don’t need to eat more than 25% above that 0.54 g/lb, which would be 0.55×1.25, which is 0.68 g/lb, or 1.5g/kg.
A spinach salad with fresh vegetables, hummus or flax seed crackers, and sardines is a common lunch for me, and has about 30g protein.
So let’s put those numbers into context. I weigh 175 pounds. If I don’t want to gain muscle, and I just want to make sure I’m getting enough protein for muscle recovery and body repair, I should eat 0.55×175, or 96 grams of protein.
Rounded up to a nice even number of 100 grams, that means I could have a couple scoops of protein powder with my morning breakfast (which I do), a can of sardines over my salad at lunch, and 4-6oz of chicken with dinner. That’s easily 100 grams, and doesn’t even count the other protein I get from seeds, nuts, grains, legumes, etc.
Frankly, this is about exactly what I do, and the rest of my diet is healthy fat (which keeps me smart, keeps my joints healthy, feeds my brain and maintains high levels of hormones), and then some vegetables and fruits
And if I wanted to gain muscle, I could eat 0.68×175, or about 120 grams. So I would basically just add in a couple handfuls of almonds and a dollop of yogurt and I’d be good to go.
So what are the risks of eating excess protein, or having your nitrogen balance too great?
First, consider that ammonia is a toxic compound to the body. Once you get close to about 1000 calories a day of protein (that’s about 250 grams), you can longer convert ammonia to urea, and you begin to build up this toxin within your body. This is extremely stressful on your internal organs, especially your kidneys.
Next, excess protein can cause dehydration if you do not drink enough water. This is because your kidneys need more water to convert ammonia into urea.
Most interestingly to me, mammalian target of rapamycin (mTOR) is a gene in your body that is directly correlated to accelerated aging. Decreased activity in THIS gene is directly correlated to caloric restrictions and lower amino acid intake. So excessive protein intake and a constantly positive nitrogen balance could actually shorten your life!
Take-away message: eat as much protein as your body needs for repair and recovery, eat a little more if you want to put on muscle, and then take in the rest of your calories from healthy fats and vegetables, with limited fruits and carbohydrates for fueling intense bouts of physical activity.