Protein intake around exercise is always a hot topic around the gym water-cooler. Is it better pre-workout? Post-workout? Intra-workout? The options seem endless. It’s well recognized from previous research that the minimum amount of protein required to stimulate muscle protein synthesis (MPS) is 20g post-training and that increasing to 40g post-training had no impact on muscle gains after exercise.(1) That said, if you can get some marginal gains from ramping up your protein post-training, why not? A new study attempts to uncover if ratcheting up your intake to 40g post-training is really worth the effort and if bigger athlete require more protein post-training.
Researchers brought in 30 young male trainees who had been training for at least 6 months prior to the study. They separated the subjects by lean body mass (LBM), a “low” group at less then 143 lb. of lean muscle mass (not total bodyweight) and a “high” group at greater than 154 lb. and used the gold-standard DEXA scans to determine LBM. They each performed whole-body resistance training routine of three sets of 10 reps at 75% of 1-repetition maximum (RM), plus a fourth set to failure in the following exercises; chest press, lat pull-down, leg curl, leg press, and leg extension. After the training session, they consumed either 20g or 40g of whey protein isolate (mixed with water) and had muscle biopsies taken at 180 and 300 minutes post-training.
The unique part of this study was that it consisted of two trials; the first consisted of the low LBM group consumed 20g after exercise and the high LBM group 40g, and in the other the protein intake was reversed. This was done in an attempt to uncover if athletes with greater lean muscle need more protein.
So, do bigger athletes (with greater lean muscle mass) need more protein after exercise?
The answer is “no”, but there is a little more to the story.
First, there was no significant interaction between protein dose and lean body mass group. In short, the muscle protein synthesis (MPS) was approximately the same in both groups at the respective protein dose. However, when researchers pooled all the athletes together there was one significant difference; consuming 40g of protein did promote 20% greater MPS compared to the 20g serving regardless of athlete size (see Figure 1.0).(2) The researchers speculated this could be due to the higher leucine concentration - a potent trigger of cell signalling pathways that increase protein synthesis - in a 40g dose of whey protein.
Figure 1.0 – Myofibrillar Fractional Synthesis Rate (FRS) At Varying Protein Doses
Bottom Line: This study shows a 40g dose of whey protein isolate taken immediately after training is superior at stimulating MPS than a 20g dose (contrary to previous research).
While the findings of this study still need to be confirmed, the findings are very interesting. My standard recommendation (and personal bias) for adult men is to consume 40g (and women 30g) of protein post-exercise. This is to not only maximize MPS but also provide amino acid support to other key system in the body like the immune, digestive, nervous system, etc. Lastly, if you’ve read my previous posts you’ll know that achieving your daily protein intake is still the most important factor and what you do around training (while important) comes second. The reality is, what your athletes or clients consume over the course of the entire day should be your measuring stick to support superior performance and recovery.
Dr. Marc Bubbs ND, CISSN, CSCS