By Teemu Virtanen
In yesterday’s article, we took a closer look at carbohydrates as the primary fuel for our body when exercising and ski racing. But carbs alone won’t give you the boost you need to perform at high level. If all you focus on is carbohydrates, your body won’t function to its full potential. You also need proteins, which are essential for a wide range of bodily processes, most notably the synthesis and maintenance of muscles, enzymes, hormones, bones, cartilage, hair, and skin. Plus, protein helps dull hunger and provides an auxiliary fuel source for endurance athletes to be used alongside fat and carbohydrate.
While protein is critical in building muscle mass, more is not necessarily better. Simply eating large amounts of lean protein does not equate with a toned body. When determining protein requirements for athletes, it's important to look at the athlete's overall diet. Athletes who consume diets adequate in carbohydrate and fat end up using less protein for energy than those who consume a higher protein diet. This means that protein can go toward building and maintaining lean body mass. Athletes need to ensure that they also are meeting needs for carbs and fat, not just protein; a recommended dose of protein is 1.2 to 2.0 grams per kilogram of body weight per day for athletes, depending on training.
When consuming a combination of carbohydrates and protein early during the post-workout period, it enhances muscular glycogen levels (the storage form of carbohydrate) above what is incurred if only carbohydrates are sent down the gullet. The ideal ratio of carbs and protein in a post-exercise meal is roughly 4:1.
Muscle growth happens only when exercise and diet are combined, timing of protein intake plays a role as well. Eating high-quality protein (such as meat, fish, eggs, dairy or soy) within two hours after exercise — either by itself or with a carbohydrate — enhances muscle repair and growth. Duration and intensity of the activity also are factors when it comes to protein needs.
In some laboratory-based “time to exhaustion” tests, during which the subject exercises at a single workload (or speed) for as long as possible, it has been proven that carbs plus protein can increase performance. However, this type of performance test is problematic since most endurance races are not a time to exhaustion and instead cover a specific distance, thus the validity of this type of test to real-world performance is questionable.
The addition of protein during exercise (or soon after) has an added benefit of creating a positive net protein balance environment, which basically means more making-new-muscle proteins than breaking-down proteins. Specifically, the ingestion of protein seems to selectively decrease protein degradation rather than enhancing protein synthesis. The positive protein balance is associated with improved performance the day following exhaustive exercise and might prove useful for athletes completing multi-day stage races or even really long ultra events that may take in excess of 24 hours.
We have now determined the importance of proteins, but let’s see what they really are. They are one of the building blocks of body tissue and can also serve as a fuel source. As a fuel, proteins provide as much energy density as carbohydrates: 4 kcal (17 kJ) per gram; in contrast, lipids provide 9 kcal (37 kJ) per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.
Proteins are polymer chains made of amino acids linked together by peptide bonds. During human digestion, proteins are broken down in the stomach to smaller polypeptide chains via hydrochloric acid and protease actions. This is crucial for the absorption of the essential amino acids that cannot be biosynthesized by the body.
There are nine essential amino acids which humans must obtain from their diet in order to prevent protein-energy malnutrition and resulting death. They are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine and histidine.
All dietary sources of protein include both animals and plants: meats, dairy products, fish and eggs, as well as grains, legumes and nuts.