Muscle Building Myths Debunked

200m from finishing the Scotiabank Toronto Waterfront Marathon

Last weekend, I ran the Scotiabank Toronto Waterfront Marathon, setting a new personal best of 2:47:20. Even more exciting, I was the 5^th Canadian woman to finish. Right now, I am taking a bit of a rest before I start my training to break that 2:45 mark. Up to now, most of my posts have been related to endurance exercise. This week, partially because I’m not partaking in endurance exercise, I thought that I would post a blog for body builders or other athletes who benefit from having a high amount of muscle mass. This is a hot topic and unfortunately, there is a lot of false information on how to best optimize building muscle mass through diet. I am going to dispel some of these common myths and share what the current research actually suggests.

Muscle mass size is dictated by the rate of muscle protein synthesis (building muscle mass) and muscle protein breakdown. Resistance exercise followed by consuming protein results in the building of muscle mass, as long as total energy intake is adequate. Muscle protein synthesis can be manipulated by the amount of protein consumed, source of protein and distribution and timing of protein intake. Muscle protein synthesis is also influenced by type and intensity of resistance exercise training. However, since this area is outside my scope of practice, I will just be focusing on nutritional factors.

Myth # 1: The more protein consumed, the more muscle mass built

There is a phenomenon called the “muscle full effect.” There is a limit to how much protein the body can use to build muscle. Protein consumed beyond this amount will not be used to build muscle. Current guidelines suggest 0.25-0.3 grams of protein/kg of bodyweight after a workout and then again every 3-5 hours. For instance, a 70kg athlete should consume about 18-21 grams of protein immediately following exercise. Check out the table below for the protein content of some common foods. Consuming protein amounts beyond this level will not have any additional benefits.

Myth # 2: It’s important to consume protein before, during and after exercise

Research does not currently support improved muscle protein synthesis when protein is consumed before and during exercise. In fact, consuming protein before resistance exercise may actually blunt muscle protein synthesis. Rather, the 0.25-0.3 grams /kg of bodyweight should be consumed after exercise. Because of the “muscle full effect” highlighted above, it’s important to ingest this amount of protein in different meals throughout the day. Typically, this should be applied to 4 meals per day (or 3 meals plus 1 snack). Current research does suggest that consuming large doses of protein pre-sleep appears to improve overnight muscle protein synthesis. This was shown when up to 0.6g of protein/kg of body weight was consumed before bed.

Myth # 3: The type of protein consumed doesn’t matter

The most commonly consumed isolated protein sources include: soy, casein and whey. Out of the three, the most effective isolated protein is whey. More interestingly, consuming a protein source with a high content of the amino acid leucine seems to be the best stimulator of muscle protein synthesis. However, the “threshold” for the amount of leucine that stimulates muscle protein synthesis is about 3 grams of leucine per meal. Consuming more than 3 grams of leucine at once will have no additional benefits. You may have noticed that the packaging of different protein powders and supplements advertise that it contains “branched chain amino acids (BCAA).” Leucine is one of the three BCAA. Isoleucine and valine are the other two BCAA. However, the addition of isoleucine and valine to leucine does not improve muscle protein synthesis and they actually compete with each other in the gut for absorption. Therefore, if you’re choosing to take a protein supplement, read the labels and choose one sourced from whey protein isolate and containing up to 3 g of leucine.

I am a firm believer, however, that food is the most ideal source of protein as it contains many nutrients that won’t be found in an isolated protein source. For those consuming their protein from food, the best source of leucine is animal based foods. See the table below for the leucine content of some different foods.

To sum up this blog post, to best build muscle mass consume 0.25-0.3g/kg bodyweight of protein immediately after resistance training and then again every 3-5 hours. Chose high quality protein sources with high amounts of leucine. Furthermore, there is no need to consume a protein powder before and during your work-out. I hope that this was an informative blog that allowed you to become aware of some of the common myths within the fitness industry and the best way to build muscle.