Building Blocks For Body Strength

By Andrea Chernus, Ms, Rd, CDE Registered Dietitian

Sorting out protein possibilities can be confusing for even the most well-informed athlete. If muscles are generating power, speed, strength and endurance, how much protein do active individuals really need? Should it come from an animal or vegetable? What about protein powders? We’ll sort out the facts from the hype so you can determine the best sources and amounts for you.

Protein Basics

It’s well established that athletes need more protein, although everyone needs protein for growth and overall health. This nutrient is used to make hormones, antibodies, new red blood cells and enzymes that “spark” reactions inside the body. Protein balances fluids and pH levels in the body, repairs muscle and other tissues and helps provide structure to hair, nails, bone and skin.  Since athletes need to repair muscle tissue more than sedentary people, they need to consume more protein. Yet we only need protein for these repair and maintenance functions. We don’t want to burn protein for energy – that job is better suited for carbohydrate and fat.

For the body to use the protein we eat, it must be broken down into smaller particles, or amino acids, which are considered the building blocks of protein. Just as letters of the alphabet make up words, amino acids are combined to form different proteins. The body can transform some amino acids into others that may be in short supply – these are called non-essential amino acids, since we don’t have to worry about which of these we consume through our diet. There are nine amino acids that we must take in from food, because the body cannot make them. These are called the essential amino acids and are all required for our body to formulate body proteins.  When all of the nine essential amino acids are present in a food, it is referred to as a complete protein. They are found in all animal-based foods: meat, poultry, fish, eggs, milk, cheese and yogurt.

The only complete plant-based food is soy.  Other plant-based foods are incomplete proteins, meaning they are missing one of the essential amino acids. Two proteins are considered complementary when they provide enough of the essential amino acids missing in the other. Examples of this are legumes and grains (beans and rice), or legumes and seeds (chickpeas and tahini).  Together, complimentary proteins provide all of the needed essential amino acids to form protein in the body. Milk, a complete protein on its own, contains enough extra amino acids to complete the protein in grains as in cereal and milk. Although complementary proteins don’t have to be consumed at the same time, within 24 hours is recommended.

Protein Quality

We’ve established that all nine essential amino acids must be present for the body to use the protein for growth, maintenance or repair. A food’s usefulness depends on how digestible the protein is, how available the amino acids become to the body, and how well the amino acids fit the pattern needed by our tissues.  Sounds complicated, but scientists have developed ranking systems to evaluate this. The most widely used scale is the Protein Digestibility Corrected Amino Acid Score (PDCAAS). This system ranks cow’s milk and egg protein the highest, with beef and soy following closely after. Other animal sources such as poultry and fish are not included in the studies, but perhaps would have been towards the top. Animal proteins are more digestible. Plant sources tend to have other elements such as fibre that interfere with full digestion. The usefulness of PDCAA for athletes is somewhat questionable. That’s because most healthy people eat a variety of foods and rarely exist on only one protein source. Many people consume far more protein than their body needs, which decreases the importance of protein quality.

Basically, if you are consuming enough protein from a variety of sources, whether it comes from eggs, milk or meat is not that important. For vegetarian athletes, consuming about 10 per cent above one’s estimated needs can help overcome the lower-quality protein in many plant-based foods. Vegans and vegetarians may need to pay more attention to protein quality than meat eaters to ensure enough of all essential amino acids are consumed on a regular basis.



How much protein do athletes need?

It’s widely accepted that athletes need more protein than sedentary people. If you consistently consume too little, muscle repair will be compromised, immunity may decline, hair, nails and bones can suffer, even anemia can occur. Too much protein can lead to dietary imbalances, constipation and decreased energy levels. Often when athletes consume more protein than they need, there isn’t room for the right amount of carbohydrate. Extra protein doesn’t result in higher levels of lean body mass because muscles can only use so much protein each day.

So what happens to the extra protein? The body will burn protein for energy if calorie needs are met. If excess protein leads to too many calories, it can lead to body fat. Knowing the optimal amount needed for your type of training can help in creating an appropriate eating plan. It is important to consume enough calories to fuel your training. Too few calories will have you burning fat and protein for energy. Not enough calories can also lead to muscle tissue breakdown and a lower
metabolic rate. 

If you are trying to lose weight, meeting with a sports dietitian can help to determine the right amount of calories to fuel training and optimize body composition.  For our purposes, let’s determine protein needs based on a stable weight for athletes.


Endurance
 
Endurance athletes include runners, cyclists, race walkers, rowers, distance swimmers and cross-country skiers. To qualify, it would be any aerobic activity carried out continuously for 45 minutes or more, at least three days a week. Most endurance athletes need 1.2-1.4 grams of protein per kg of body weight per day.
The lower intensity, shorter duration sessions require intake at the low end, while higher intensity, longer sessions need a higher intake. More eccentric movement such as running downhill causes greater muscle tissue damage and can slightly increase protein needs, as can requirements for ultra-endurance athletes who are training for extended periods of time. Highly competitive athletes training for long endurance may need up to 1.8 g/kg of protein.

Strength

Weight lifting increases protein needs, but not as much as you may suspect. Even the hardest working athletes don’t need more than 1.8 g/kg of protein per day. Adequate calories are also important so the protein consumed is available to repair muscle tissue. Many athletes don’t realize that only 15 to 20 per cent of muscle is comprised of protein. The remainder is water, stored carbohydrate and small amounts of fat and minerals. Consuming large amounts of protein does not mean muscle tissue has the ability to absorb it all. Consider a sponge that is already saturated: it can’t accommodate any more liquid. Also realize that muscle tissue needs between 24 and 48 hours to repair any damage. Muscles take up the amino acids over time after exercise, so the body will utilize smaller doses more effectively than one large dose. Athletes trying to build muscle mass need 1.6-1.8 g/kg of protein daily (novice athletes at the higher end). Athletes engaging in lighter strength training for toning or maintenance need 1.2-1.4 g/kg of protein per day.

Andrea Chernus is a registered dietician and co-author of Nutrient Timing for Peak Performance (Human Kinetics, June 2010)

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