Protein is the nutrition holy grail of muscle building. The body is constantly in a fluctuating state of muscle loss and gain, which means that the more often you trigger protein synthesis (the process via which the body builds muscle), it is a good thing.
Eating protein is one way to stimulate protein synthesis. The other is by lifting weights, which is why putting the two together is the best way to optimize body composition. Body builders have long known that this powerful combination of training and protein will give you maximal gains, but what they weren’t sure about was how MUCH protein or how MUCH training yields the greatest results. New research provides insight into both questions.
A study from Canada set out to determine the protein dose that yielded maximal muscle development in a group of highly trained male body builders. The researchers used a unique approach whereby instead of testing nitrogen balance they used something called the IAAO technique that identified the point at which point oxidation of an “indicator” amino acid (in this case phenylalanine) remains steady. Once dietary protein needs are met, there is no change in the oxidation of the indicator amino acid and the resulting “breakpoint” is thought to be the requirement.
To ensure a highly trained population, researchers assessed each participant based on an Index of Muscularity. All the subjects had a Muscularity relative to height that was greater than 90 percent, which meant that they had at least 16 kg of lean mass more than your average healthy young, non-bodybuilder of the similar height. All subjects were steroid free and natural. The researchers tested a wide range of protein intakes (from 0.1 to 3.5 g/kg a day) and provided a hypercaloric diet that supplied 1.5 times each individual’s measured resting energy expenditure.
Results showed that the protein requirement to sustain muscle and offset protein breakdown was 1.7 g/kg, whereas the recommended requirement for which maximal muscle building occurs was 2.2 g/kg.
Researchers note that when it comes to protein requirements there are 4 different states:
- Protein deficiency when maximal reduction in protein synthesis occurs in all but the essential organs.
- Accommodation in which balance is achieved via a decrease in physiologic relevant processes.
- Adaptation where optimal growth, interorgan amino acid exchange, and immune function are present.
- Excess, which is characterized by amino acid oxidation for energy—a situation in which no further stimulation of protein synthesis occurs.
Body builders who are interested in optimal muscle growth should be in the Adaptation state and this is the dose represented by the 2.2 g/kg recommendation. The 1.7 g/kg “requirement” amount would allow for Accommodation by which muscle is not lost, assuming strength training is being performed concurrently.
This is certainly not the first study to explore protein requirements in serious lifters. Could there be any benefit to an even higher protein intake when combined with training?
Possibly, although when you get much above 2 grams of protein daily, it becomes harder to avoid developing protein intolerances and gut issues, so that is something to consider if you’re thinking of embarking on a super high protein diet.
A 2014 study compared a diet that supplied 3.4 g/kg of protein with one that had a “normal” protein intake of 2 g/kg of protein in trained men and women who were doing an intense strength training program. The extra protein in the high-protein group was supplied from whey or beef protein powder.
Results showed that the high-protein group lost 1.6 kg of fat mass, decreased percent body fat by 2.4 percent and increased lean mass by 1.5 kg. The normal 2 g/kg group lost 0.3 kg of fat, decreased percent body fat by 0.6 percent and increased lean mass by 1.5 kg. Both groups improved vertical jump, squat, bench press, and pull-up performance.
Because lean mass gains were similar, it’s unlikely that the higher protein intake (3.4 g/kg) provided any hypertrophy benefits. This study supports the first study we discussed, which showed that in the range of 2.2 g/kg will maximize muscle building results in serious, young trainees. However, there was a significant difference in body fat with the high-protein group losing significantly more fat despite eating about 400 more calories per day.
It’s possible the greater loss of fat mass may be due to the higher protein intake increasing energy expenditure during sleep and daily life. There was surely a thermic effect in the higher protein group such that the number of calories burned during digestion and assimilation increased more in the 3.4 g/kg group.
Additionally, researchers suggest the high-protein group may have increased their activity levels for a greater daily calorie burn. A previous study found that overfeeding produced an increase in energy expended in physical activity. This is the opposite effect of what happens when people cut calories. When dieting, people tend to decrease physical activity and lower their daily energy expenditure (likely an unconscious effect of the hypothalamus in the brain to prevent weight loss when fuel sources are scarce). Another possible explanation is that the more advanced training status of the high-protein group could lend itself to greater energy expenditure in daily life.
Now that you’ve got protein intake covered, what training program is best for maximizing muscle?
Research shows that there are two primary mechanisms of muscle growth:
- Muscle tension, which refers to the amount of time spent lifting. Greater volume with more sets and more total reps lead to greater mechanical tension and a larger stimulus to the muscle to grow.
- Metabolic stress, which leads to cell swelling and release of hormones and other molecules that stimulate muscle growth. Training to failure with a higher volume leads to greater fatigue and metabolic stress.
Muscle damage, which mainly occurs with the eccentric (lengthening) motion of an exercise, may also play a role, however, the research is unclear on its impact. We know for certain that muscle hypertrophy can occur in the absence of muscle damage, and the soreness associated with muscle damage may impair a high training frequency.
A consistent finding is that the more high-quality training you perform, the greater muscle growth you will experience. You can put this in practice by alternating between accumulation and intensification training cycles:
Accumulation maximizes volume with higher reps and sets and more moderate loads. Shorter rest periods are used to enhance metabolic stress and elicit the buildup of lactate and cytokines that lead to enhanced protein synthesis and muscle development.
Intensification uses heavier loads to target the higher threshold muscle fibers that are not trained with lower weights. Higher intensities require lower total reps and sets and longer rest to ensure the quality of training is maintained.
Final Words: To get everything possible out of your muscle growth efforts, combine a threshold daily dose of 2.2 g/kg of protein with high-quality training that alternates between intensification and accumulation. This will allow you to target the highest threshold muscle fibers, stimulate growth with tension and metabolic stress, and supply the body with the amino acid building blocks needed to maximally stimulate protein synthesis for the greatest results.