Dating back as far as Ancient Greece and the Olympics, athletes have added protein to their diets to modify the effects of training on physique and performance. Conventional thought held by many athletes and coaches is that very high dietary protein intakes are needed to maximize protein metabolism within a muscle leading to faster repair and hypertrophy, the increase in cell size. But what does the current research suggest is the adequate amount of dietary protein intake for differing forms of exercise as well as the gender and performance level of the athlete?
In this blog I will try to provide the answer in a comprehensive yet simple review on this hotly debated topic.
Generally speaking, most athletes engaging in resistance exercise desire to increase their muscle mass, strength, and power. Whereas, endurance athletes are looking to augment longer duration output, such as increased maximal oxygen consumption, or reduce body fat.
Now before I jump right into discussing adequate protein intakes for resistance exercise, I want to address endurance athletes first because even these athletes need to pay attention. Multiple studies have shown that endurance exercise increases the breakdown and utilization of protein for energy as you increase the intensity of the exercise and depending on the state of training of the athlete. A recent study by McKenzie et al evaluated protein usage in both male and female athletes during a 38-day high intensity endurance training program. They found that:
- the body used more protein at the beginning of the 38-day training compared to the end indicating the importance of knowing an athlete’s training status,
- the body used more protein when there was a depletion of carbohydrate availability,
- the body used more protein when the athletes pushed themselves to higher intensities during the workouts,
- on average the protein usage accounted for 1-6% of the total energy cost for the endurance workouts, and
- women tended to use less protein then men during the workouts.
Other studies looking at athletes engaging in low to moderate intensity endurance exercise programs indicate that these athletes need the same amount of dietary protein intake or only slightly above that of a sedentary individual.
So how much protein should an athlete consume given the intensity of their endurance workouts?
Recreational endurance athletes who are exercising 4 to 5 times per week for 30 minutes below moderate to high intensities need about 0.80-1.0 grams of protein per kilogram of body weight per day. This is the same for sedentary men and women.
Moderate intensity endurance athletes who are exercising 4 to 5 times per week for 45 to 60 minutes need about 1.2 grams of protein per kilogram of body weight per day.
Elite high intensity endurance athletes (regular marathon runners and triathletes) need about 1.4-1.6 grams of protein per kilogram of body weight per day.
And in general, dietary protein recommendations for female endurance athletes may be 10-20% lower than males.
Surprisingly, these recommended values are much lower than the average protein intakes of most male and female endurance athletes. The typical male and female endurance athlete today consumes about 1.8 and 1.3 grams of protein per kilogram of body weight per day, respectively.
So now that I’ve summarized the adequate protein intakes for endurance athletes let’s switch to protein requirements for resistance training athletes. First off, resistance exercise is different than endurance training in that a primary end goal is muscle hypertrophy or the increase in muscle size. Therefore it would only make sense that protein intake will need to be in excess that of basic sedentary requirements to provide the building blocks for muscle repair and growth, right? Well what does the research say?
A study way back in 1988 by Tarnopolsky et al calculated how much protein intake it would take to match protein metabolism in 6 well-trained bodybuilders compared to 6 sedentary people. Surprisingly, they found that only 12% more protein intake was needed for the bodybuilders. Even more surprisingly, the bodybuilders were regularly consuming protein amounts of 2.7 grams of protein per kilogram of body weight per day which if you look back above you’ll find that this is 170% more the recommendations for sedentary people of 1.0 grams. (Also remember that recreational endurance athletes and sedentary individuals are at the same recommendation.)
Now this study was looking at resistance athletes at steady state given the bodybuilders had at least 2 years of consistent training. The recommended protein intake for steady state resistance athletes is 1.0-1.2 grams of protein per kilogram of body weight per day.
What about people in the early stages of resistance training? Do they need more or less protein intake?
4 years later Lemon et al answered this question by calculating the estimated protein requirement during the early stages of resistance training. They had 12 young men participate in 2 months of resistance training and split them into two groups having them intake either 1.4 or 2.6 grams of protein per kilogram of body weight per day. The men exercised 6 days per week for 2 hours each day. The weights were set to 70-85% the maximum weight that they could only do 1 repetition of. They found that the estimated protein requirement during this early stage of resistance training was 1.6 grams of protein per kilogram of body weight per day.
Would you be surprised if I told you that the average resistance athlete today is consuming far more their needed protein requirements regardless of their stage of training in resistance exercise? Probably not since I’ve already told you this is true for two other situations above. The average resistance athlete today consumes 2.0 grams of protein per kilogram of body weight per day. This is 25% more than the amount needed for early resistance training athletes (1.6 grams) and about 80% more for steady stage resistance training athletes (1.1 grams).
At this point I might be hearing a pour of outrage from some athletes believing they still need more protein to meet the demands of their resistance training, usually from the intense football or rugby player. So let’s look at the protein requirements for football and rugby athletes involved in weight-training and high-intensity sprinting and power activities as evaluated by the research of Tarnopolsky et al in 1992. They found that the protein requirement for this group at the highest was only 1.7 grams of protein per kilogram of body weight per day. This is only slightly higher than those athletes who are early on in their resistance training.
So to recap, see below the listed protein requirements for the various athlete type measured in grams of protein per kilogram of body weight per day.
- Sedentary people: 0.80-1.0
- Recreational endurance: 0.80-1.0
- Moderate intensity endurance: 1.2
- Elite high intensity endurance: 1.4-1.6
- Early stage resistance training: 1.5-1.7
- Steady state resistance training: 1.0-1.2
- Power sports like football or rugby: 1.4-1.7
- Female athletes: on average need only 10-20% lower than male athletes
I know this is a lot of information but I hope you found this blog to be informative. Perhaps you will save some money on protein supplements or foods by knowing these recommendations. If you have any questions about how Dr. Wilson’s expertise in sports medicine could help you or have other Chiropractic questions, please call Gaitway Chiropractic in north Spokane at (509) 466-1366, request an appointment online, or come by the clinic at 8611 N Division St, Ste A, Spokane, WA 99208.
Lemon PW, Tarnopolsky MA, MacDougall JD, Atkinson SA. Protein requirements and muscle mass/strength changes during intensive training in novice bodybuilders. J Appl Physiol 1992;73:767-75.
McKenzie S, Phillips SM, Carter Sl, Lowther S, Gibala MJ, Tarnopolsky MA. Endurance exercise training attenuates leucine oxidation and BCOAD activation during exercise in humans. Am J Physiol endocrinol Metab 2000; 278:E580-7.
Tarnopolsky MA, MacDougall JD, Atkinson SA. Influence of protein intake and training status on nitrogen balance and lean body mass. J Appl Physiol 1988;64:187-93.
Tarnopolsky MA, Atkinson SA, MacDougall JD, Chesley A, Phillips S, Schwarcz HP. Evaluation of protein requirements for trained strength athletes. J Apply Physiol 1992;73:1986-95.