The adequate amount of protein intake for an athlete who trains regularly in resistance and cardiovascular endurance, according to the USRDA and backed by a study from the International Journal of Sport Nutrition and Exercise Metabolism (2007), is approximately 1.2 to 1.7 grams of protein per kilogram of body weight (4). Campbell et al (2007) reported that a dietary intake of protein ranging from 1.4 to 2.0 g/kg of bodyweight was imperative to protein synthesis resulting in physiological adaptations to the muscle (1).
A study by Furhman and Ferreri (2010), a minimum protein intake for zero nitrogen balance in strength athletes was 1.41 g/kg of body weight (3). In my situation, weighing 205lbs (93kg), this would equate to 111 to 158 grams of protein per day. This equates to 444 to 632 calories per day coming from protein. In my estimated 2200 calorie per day requirement, this would be approximately 20% of my calories from protein. Given that I eat approximately 5 meals per day, this would average out to 22 to 31 grams of protein per meal. Potential problems exist when protein intake does not meet the necessary protein synthesis requirements of the athlete, which include, but not limited to a negative nitrogen balance.
Functioning on a vegan diet, there is a definite difference in the quality of protein that is consumed throughout the day. A vegan diet, which has several different levels, is common to not ingest foods of animal origin (3). This includes not eating meat, fish, dairy or any food from an animal origin. It is commonly referred to as a plant based diet, but not excluding grains, legumes, and nuts. The concern with this type of diet is that these foods rarely consist of all 20 amino acids that are required for protein synthesis to occur.
These foods of the vegan diet, are commonly referred to as incomplete proteins, however, there are several “non-animal” foods that do provide all 20 amino acids. These foods are soy, quinoa, buckwheat and a few others. The concern of an athlete consuming a vegan diet is not ingesting enough of the complete proteins to allow for muscle repair to occur. From a personal perspective, for 12 months I maintained a vegan diet, which was consistent with the guidelines of no animal sources for food intake. It was strictly fruits, vegetables, nuts, legumes, and grains.
The challenge with consuming adequate protein was that foods high in fiber and water content made it more difficult to consume the necessary caloric and protein requirements set by the RDA. To maintain proper protein intake during intense training, I consumed a vegan based protein powder which contained all essential amino acids required for protein synthesis. I found that in order to meet the demands I was placing on my body, consuming additional protein became exceptionally critical especially following a resistance training routine. Bilsborough and Mann(2006) concluded that adding protein to carbohydrate supplementation during exercise did not increase performance, however, it did aid in protein synthesis which occurred following a bout of resistance training (1).
Attempting to lose weight is a common motivation in society today, and unfortunately, so much emphasis is placed on the number on the scale. So common in weight loss participants, fat in addition to muscle, is the combined result from weight loss. In order to help maintain muscular conditioning, if the goal is to diminish fat reserves, then it is extremely important to maintain adequate protein intake for muscle and cell repair. Reduction of calories should come from high glycemic foods such as breads, pastas, white rice, white potatoes and the like. Most importantly, a reduction or elimination in refined and or processed foods, such as crackers, cookies, chips, and deserts. Protein, which adds nitrogen to the carbon, oxygen, and hydrogen, is still an energy source for the body during high stress activity. Approximately 5% of the calories burned during exercise are derived from the breakdown of protein into glucose (3). It is very critical to maintain the upper level of recommended protein intake per kilogram of body weight.
Nitrogen balance to be maintained in our bodies is essential to provide muscle and cell repair that has been damaged during high stress events, such as exercise. Out of the macronutrients: fat, carbohydrates and protein, all of these contain hydrogen, oxygen and carbon. Protein is the only macronutrient that contains nitrogen, which is essential for amino acids to build a protein molecule. If too much protein is broken down to provide glucose to the body, and then the body will not be able to complete protein synthesis to repair damaged cells (muscle tissue). This is critical for any athlete looking to increase muscle size during high stress activities, such as resistance training.
- Campbell B; Kreider RB; Ziegenfuss T; La Bounty P; Roberts M; Burke D; Landis J; Lopez H; Antonio J.International Society of Sports Nutrition position stand:Protein and exercise, Journal Of The International Society Of Sports Nutrition, 2007; Vol. 4, p. 8.
- 2- Bilsborough S & Mann N. A Review of Issues of Dietary Protein Intake in Humans. IJSNEM, 16(2), April 2006, 129-152.
- Fuhrman, J., & Ferreri, D. M. (2010). Fueling the Vegetarian (Vegan) Athlete. Current Sports Medicine Reports (American College Of Sports Medicine), 9(4), 233-341.
- Phillips, S. M., Moore, D. R., & Tang, J. E. (2007). A Critical Examination of Dietary Protein Requirements, Benefits, and Excesses in Athletes. International Journal Of Sport Nutrition & Exercise Metabolism, 17S58-S76.