“Skeletal muscle protein turns over at a rate of about 1-2% per day. The latter implies that skeletal muscle tissues is broken down and rebuilt approximately every 3 months.”
– Prof. Luc van Loon, “Dietary Protein as a Trigger for Metabolic Adaptation”, Sports Nutrition: The Encyclopedia of Sports Medicine.
In other words, your muscles completely replace themselves every 90 days–faster than the turnaround in most LA strip malls. So it’s crucial to continually eat the right proteins to assure you’re effectively building the healthiest body mass. That much is obvious. But if you’re interested in making the most of this constant rebuilding–whether you want to perform better at your chosen activity, stay healthy, or just look good in your bathroom selfies–there are a few ways you can adjust your eating strategy as it relates to working out.
(Full disclosure: the following is a snarky, layman’s book report version of the encyclopedia entry I quoted above–with a little of my own homespun wisdom thrown in. Sports Nutrition is a eyebrow-deep, slide rule-to-eleven, hardcore scientific nerdfest. If you’re into performance nutrition, it’s sexier than well-applied green body paint at a Comic-Con. Well worth the 200 clam price tag.)
Two things stimulate protein synthesis (muscle building): eating and exercise. Some might include drugs in this list, but I’m going to keep things clean for now. Exercise also promotes protein breakdown, meaning it wears out your muscles. (Duh.) But luckily, it promotes synthesis even more. The type of exercise you do also heavily impacts what proteins in your muscles are favored. If you do a lot of resistance work, your myofibrillar proteins, the ones that add strength and structure, build up. If you do a lot of endurance exercise, your mitochondrial proteins, the ones that work the little engines in your cells, build up. This explains why bodybuilders get huge, but sometimes get winded taking the stairs while cyclists tend to look like beanpoles, yet can… keep… riding… forever…
Now let’s add eating into the mix. While carbs do all kinds of great things, like replenish glycogen stores, inhibit breakdown, and help recovery, they don’t build more muscle. To build muscle, you need to eat protein. If you’re unclear on what protein is exactly, here’s a little refresher course from the Beachbody Blog, crafted by Yours Nerdily.
For your body to function at its best, it needs 20 different amino acids, 11 of those your body makes. The other nine—known as “essential amino acids”—come from your diet. (There used to be eight, but it was recently discovered that adults can’t synthesize histidine.) Any protein that contains all nine essential amino acids in adequate levels is called a “complete protein.”
So here’s the cool thing. If you eat after you exercise, your stimulated system better uses the amino acids you’re feeding it. It’s like giving a bricklayer a quadruple cappuccino then supplying him a shitload of bricks. He’s gonna build a wall, and he’s gonna build it fast.
While this espresso effect probably hangs around for about 24 hours, it peaks at about 2-3 hours after exercise, meaning you want to consume some protein (20g-24g) immediately after your workout so that it’s well into your system when this peak hits.
You can increase this synthesis even more with a carb/protein mix before and during exercise, particularly high intensity interval training, because this further insures you have all the amino acids you need post-exercise.
But sometimes don’t do this.
Because we don’t store protein the way we store carbs and fat, it’s important to get a little with every meal, but there are times when pre-and-post-exercise protein might not be ideal, particularly if weight loss is your goal. If dropping pounds is your primary thing, I’d probably avoid fueling before and during working out because exercising in a fasted state promotes the mobilization of fat stores for energy. This can also be useful for endurance athletes trying to train their bodies to function more efficiently on less feeding.
Also, ingesting carbs after a workout is a good way to reestablish glycogen stores. (That’s the back-up blood sugar supply in your muscles that gives you the energy you need to get through hard efforts.) If you’re in a situation where you’re punishing yourself several days in a row, whether you’re doing the Tour de France or P90X2, having that energy is important. If you’re not trying to lose weight, no problem. Just throw all those carbs and protein together post-workout in one, big, calorific shake, gulp it down, and prepare for some serious burping and farting. But if you’re focused on weight loss, a 300+ calorie beverage might not be your cup of tea, so you’ll want to experiment. If you’re having a tough time getting through your workouts, I’d edge up the carbs. If you’re sore all the time, I’d probably edge up the protein. It really depends on your body.
Either way, when you’re working out, don’t skimp on protein in your breakfast, lunch, and dinner. Your bricklayer needs his bricks.
Milk proteins post-exercise is the whey to go.
If you choose to supplement protein post-exercise, you want a faster-absorbing one. Because of this, whey, which comes from milk, is a good choice. Whey is also a good source of the essential branch chain amino acid leucine–which to explain requires an even deeper level of nerdiness. Ready? We’re goin’ in!
Leucine plays a major role in activating a pathway called the mammalian target of rapamycin (which some may recognize from Harry Potter and the Mammalian Target of Rapamycin, the oft maligned eighth book in the series), or mTOR, that allow substances like growth hormones and amino acids to get to muscles so they can make them bigger and stronger.
Leucine needs special amino acid transporters to get to muscles in order to active those pathways, the primary one being LAT1, also known as SLC7A5 (who I believe was also the love interest from George Lucas’ first film, THX1138). And get this: one of the best ways to stimulate LAT1/SLC7A5 is resistance exercise! So, to bring things full circle, exercise stimulates the body’s ability to better use protein and protein stimulates the body’s ability to build muscle.
Midnight snacks, justified.
For years, muscle-heads pushed protein before bed based on the theory that it prevented muscle wasting during sleep. This bro science never made sense to me given the body is actually quite good at building muscle during sleep. However, newer research shows the bros might have had a point, even if their science was debatable. A few studies now show that taking casein protein (a slow-absorbing dairy protein) before bed promotes protein synthesis. In other words, it’s not preventing wasting as much as helping your muscles build and repair even better.
So there’s a lot to take in there. As the Dude would say, it’s a very complicated case. A lot of ins, a lot of outs, a lot of what-have-yous. Luckily, if you don’t want to bother with all this timing and grams of this and percentages of that, you can always just make a point of getting some protein in every meal and hoping for the best. That said, I’d encourage you to experiment a little. Buy a tub of whey and a tub of casein. Try them after working out and before bed.
Best case, they push your performance to the next level. Worst case, you’re stuck with a couple of ugly bookends.