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As mentioned before, the structural components of the body are made out of proteins. There are certain cells or tissues in the body that make proteins very rapidly, and there are others that do so more slowly. Skeletal muscle is actually on the slower side of the spectrum. However, since skeletal muscle is such a large tissue (roughly 40% of body weight), it is quantitatively the most important site of protein turnover (making and breaking down of protein). In the sport of cycling, skeletal muscle is what propels the bike. Thus, having a good understanding of how to maintain skeletal muscle proteins, and keep them in a good state, is important for cycling performance. In this column, I will talk a little bit about what builds up and breaks down protein and some strategies to potentially help that.


In skeletal muscle, there are two things that tell the muscle to build – feeding of protein and activity. Not all tissues respond to these two signals and a quick explanation of why this is can help with the understanding of the whole process. It is readily apparent to most people that adipose tissue is the storage site of fat. Similarly, glycogen is the storage form of glucose. Few consider that skeletal muscle can act as a storage site of protein. The reason why is that given its mass, skeletal muscle can sustain losses of protein without compromising life. Other tissues cannot do this. For example, if we stored protein in our skin when we were short of protein our body would start breaking down skin, which is not conducive to survival. When we eat proteins, the proteins are made up of essential and non-essential amino acids. By definition, non- essential amino acids must be obtained from the diet because the body cannot synthesize them. Therefore, if a person consumes food containing protein, the essential amino acids in that protein tell the skeletal muscle that protein has been consumed and it is a good idea to store it. The root of this kind of response is that our genome evolved during feast and famine conditions and our body was designed to store nutrients when nutrients were plentiful to sustain itself during periods of famine. The essential amino acid leucine is particularly powerful at turning on the pathways that lead to protein synthesis (or storage). Physical activity is the other signal to make proteins. Previous columns have explained in detail how this works. In short, activity is a stimulus that the muscle has to respond to and it responds by making proteins.

The previous paragraph explained the making of new proteins, or what is called protein synthesis. For a muscle to become better at what you want it to do (in this case cycling) it needs to make new and better proteins. It should be obvious to you that you cannot just sit around eating protein all day to get better at cycling, and there are reasons for that (which will not be covered here). However, some are aware that it is generally a good idea to eat protein after exercise. Why is eating protein right after a bout of exercise important? It goes back to the signals that turn on the making of protein. When you go for a bike ride, your wants to adapt to that bout of exercise so it is easier next time. There are signals that go to the nucleus of the cell to copy a message from the DNA. This message is sent out as a blueprint to make the proteins that are important for adapting to that stress (process is called transcription). Whereas sending out the blueprint is important, having something build the proteins using the blueprint (what is called translation) is equally important. It turns out that essential amino acids (such as leucine) are really good at turning on the machinery to build the proteins from the blueprint. Therefore the combination of physical activity to make the blueprint, and the consumption of amino acids to build the protein from the blueprint, is a very good combination.

The amount of protein that is required to turn on the building of the proteins is not very much. It seems as though 16-20 grams of protein is enough to maximally stimulate this process. By maximally, I really mean maximal, because consumption above 16-20 grams just generates expensive urine. Another important point is that the protein does not have to come in any special form and real food is a really great way to get the protein. For example, an 8 oz serving of Noosa honey yogurt has 18 grams of protein. Since dairy is a high quality protein, the yogurt will contain a good amount of essential amino acids that will turn on protein building.

There has been some discussion of late on whether or not the timing of the protein intake is important. From the available data, I am of the opinion that the timing is not as critical as once believed. I think if you have a reasonable amount of protein during the day (1.0 – 1.2 grams/kg body weight), you will have the same result. We published data that showed that the timing becomes important if someone is in negative energy balance (trying to lose weight) but not so much in other conditions. I have included a reference for one of those papers at the end of the article. There is also some discussion as to whether activities such as aerobic exercise benefit from protein consumption like strength training do. From the data available I am of the opinion that it does.

The ability to make the appropriate proteins (protein synthesis) after exercise training is critical to becoming better at the chosen activity. There are things that can be done to make sure one responds favorably and that entails providing the appropriate stress (to make the blueprint) and the correct nutrition (to build the product). As I have stated before, the proper nutrition cannot make you better than what you are, but it can make sure you get the most benefit from what you are doing.

More reading:

Miller, B. F. (2007). Human muscle protein synthesis after physical activity and feeding. Exercise and Sport Sciences Reviews, 35(2), 50–55. doi:10.1097/jes.0b013e31803eac78

Minor, B. D., Heusinger, D. E., Melanson, E. L., Hamilton, K. L., & Miller, B. F. (2012). Energy Balance Changes the Anabolic Effect of Postexercise Feeding in Older Individuals. The Journals of Gerontology Series a: Biological Sciences and Medical Sciences. doi:10.1093/gerona/gls080