What macronutrient are most bodybuilders completely obsessed with? Protein, of course! Protein is made up of long chains of amino acids, the building blocks of proteins. Amino acids link with each other to form chains held together by strong peptide bonds. In total, there are twenty amino acids each differing from each other by their unique side chains. These side chains give an amino acid in one part of the chain the ability to bind with another elsewhere in the sequence to form unique protein structures that bend and fold. Because of these additional linkages proteins can take on a variety of shapes and even fold or form globular structures.
Why Protein and Amino Acids?
It’s hardly surprising that bodybuilders are fixated on protein. During a weight training session, you damage and tear muscle proteins and that damage must be repaired. During the repair process, satellite cells bind to the damaged muscle fibers and donate contractile elements called myofibrils, thereby increasing the size of the fibers. This process of repair is enhanced by growth factors, like insulin, growth hormone, and IGF-1, and ultimately leads to muscle hypertrophy.
For muscle repair and growth to take place, you must supply muscle fibers with the building blocks they need, specifically, amino acids from protein. At one time, experts believed that to maximize muscle growth, you needed to eat a combination of carbohydrates and protein (a ratio of about 3:1) within an hour of a workout. The thought was that there’s a post-workout anabolic window where your muscles are primed to take up the amino acids from protein and use them for muscle repair.
Based on more recent research, it’s likely that the anabolic window period applies mainly to training in a fasted state where glycogen stores are already low. Otherwise, you have more leeway. Waiting up to four hours after a workout, assuming you haven’t fasted, probably won’t significantly impact muscle growth or repair, as originally thought. Now, let’s look at WHY you need protein after a workout.
Get a Leg Up on Muscle Repair
As mentioned, weight training places stress on muscles and, when the stress is great enough, it creates microscopic tears in muscle fibers that must be repaired. It’s during the repair process that muscles grow. As discussed, muscles need the help of satellite cells and amino acids from protein to repair the damage. Some amino acids your body can make but there are nine that it cannot and must get through diet. Getting a dose of protein containing a variety of amino acids gives muscles the nutritional support they need to repair and grow.
Branched-chain amino acids, particularly leucine, jumpstart muscle growth after a workout. It’s leucine, along with isoleucine and valine, that activate the mTOR pathway for muscle repair and growth. The mTOR pathway is also sensitive to energy status. If you’re depleted of energy, it doesn’t turn on. So, a post-workout snack that contains protein ensures that your body has the protein and calories it needs to turn on anabolic pathways, like mTOR.
If you’re not training fasted, no need to guzzle a protein drink or eat a protein snack right away, but make sure you’re getting ENOUGH total protein over the course of the day and don’t delay that post-workout snack too long. Your muscles need carbohydrates not only to repair but to replenish glycogen as well.
Stop Muscle Catabolism
Another reason you need protein after a workout is to reduce muscle catabolism or breakdown. After a workout, the last thing you need is to break down muscle tissue. Muscle breakdown is mainly a problem when you do long, endurance workouts, especially if you didn’t fuel up properly beforehand. During prolonged periods of exercise, you deplete glycogen. As a backup fuel source, your body starts to burn a higher percentage of protein. Your liver can convert the amino acids from protein into glucose. With exhaustive exercise, that backup glucose source comes in handy. Where do the amino acids come from? Mainly from muscle proteins.
Exhaustive exercise also stimulates the release of cortisol, a stress hormone produced by the adrenal glands. Cortisol’s influence further stimulates muscle breakdown. Getting protein and carbohydrates (to replenish glycogen) helps reduce catabolism and muscle breakdown. So, getting protein and carbohydrates into your body in a reasonable period of time after a workout and getting enough protein is important for muscle preservation.
Support Immune Health
Refueling after a workout may also help you avoid a cold or viral infection. Whey protein, in particular, is linked with healthier immune function after a challenging workout session. Intense or prolonged exercise is stressful for your body and can suppress the function of white blood cells that fight infection. Whey protein, based on research, helps ramp up your body’s natural defenses against viruses. As mentioned, intense workouts and workouts of long duration stimulate the release of cortisol. The release of cortisol suppresses your body’s ability to mount an immune response. That’s why physical or mental stress increases the risk of developing an infection. Refueling within a few hours of a workout supports the health of your immune system.
Don’t forget about carbs. Consuming carbs during and right after a workout helps limit the release of cortisol and, in turn, reduce suppression of your immune system and muscle breakdown. So, protein and carbohydrates are essential dietary components for adequate exercise recovery.
The Bottom Line
Now, you know why you need protein (and carbohydrates) after a workout but it’s most important to make sure you’re getting enough total protein in your diet. With so many sources of protein available, both animal and plant-based, you don’t have to resort to supplements, although a whey protein shake is a convenient way to supply your body with protein quickly. Just make sure you’re not waiting too long after a workout is over to get your protein and carbs.
References:
Int J Sport Nutr Exerc Metab. 2009 Apr;19(2):172-85.
Journal of the International Society of Sports Nutrition. BioMed Central, 29 Jan. 2013. Web. 26 Feb. 2016.
Curr Opin Clin Nutr Metab Care. 2010 May; 13(3): 230–235. doi: 10.1097/MCO.0b013e32833781b5.
Immunology and Cell Biology (2000) 78, 554–561; doi:10.1111/j.1440-1711.2000.t01-6-.x
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