You can’t just sprinkle whey powder on your pecs: The protein on your plate can wind up forming the stress hormones that degrade muscles or the structures that build them. Understanding protein’s path through your body, though, can help you ensure it ends in muscle protein synthesis.
Exercise scientists Colin Willborn, Ph.D., from the University of Mary Hardin-Baylor in Texas, and Oliver Witard, Ph.D., of the University of Stirling in the U.K., help us explain how eggs become abs.
1. DIGESTION
When you nosh on a burger or pound a protein shake, specialized acids and enzymes in your stomach and intestines get to work, breaking down the protein into amino acids, your muscles’ building blocks. While your body creates most of the amino acids it needs on its own, the most important ones for building muscle, including lysine and histidine, aren’t produced in the body and can be obtained only from food.
Meat, eggs, dairy, and complete protein powders contain the widest array of these essential amino acids, including the branched-chain amino acids (BCAAs), one of which spurs muscle protein synthesis all on its own (more on that later).
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2. TRANSPORT
The amino acids are transported to your liver and then make the rounds in your bloodstream. If some of the proteins in your muscle fibers have been sloughed off from regular turnover or a tough workout, the blood shuttles the amino acids to the muscle cells (a.k.a. fibers) that need them. Apart from water, muscle is almost entirely protein, so growing muscle depends on building two key protein structures: myofibrils (rope-like structures built of intertwining protein strands) and sarcoplasm (an energy-rich gel that surrounds the myofibrils).
If you’re active, those ropes are continually fraying, repairing, and tacking on new strands for added strength and size, meaning you should eat 20 to 40 grams of protein four times a day for the greatest growth. If you haven’t taxed your muscles lately, amino acids are mostly delivered to less protein-hungry processes, so you don’t need as much of the macronutrient.
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3. PLANNING
Your workout determines what the amino acids will become when they hit your muscle fibers, myofibrils or sarcoplasm. Strength training alerts your body that the muscle needs more myofibrils for increased strength, while cardio sends a request for your muscle to bulk up the sarcoplasm’s power plants, called mitochondria, for improved stamina.
One BCAA, though, leucine, sidesteps this process to flip an enzyme-powered switch in the muscle fiber and set it to building mode. It’s not an excuse to skip the weight stacks, but loading up on leucine-rich foods like beef, chicken, fish, dairy, and eggs might make your off-days a little more productive.
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4. BUILDING
Based on your muscle’s needs, info housed in their fibers’ DNA calls up specific amino acids to bat, tells them how to bond together to form protein molecules, and points them to their position in the muscle fiber through a process called muscle protein synthesis. Once the new proteins take their spots, they automatically get to work, helping you max out higher, run faster, and score those bulging biceps you’ve been vying for.
Read the abbreviated article in the April 2014 issue of Men’s Health magazine or watch the video online at MensHealth.com