Is protein distribution dead?

Best practices in sports nutrition point athletes to eat protein in moderate doses throughout the day to maximise muscle growth. A recent study explored what happens when a large dose of protein is ingested after resistance training, raising the question: Is protein distribution dead?

Current recommendations

Current sports nutrition recommendations are to consume around 25-30g of protein per meal in order to maximise muscle growth. Many people consume more than that at lunch and/or dinner; for example, 1 medium Scotch fillet steak has around 50 grams of protein and 1 medium chicken breast around 55. The general consensus has been that the extra protein is not required to stimulate muscle protein synthesis but can count towards the athlete’s total protein intake for the day. In the past, some people have argued the extra protein is excreted as the body is unable to absorb it, however this does not seem to be the case at all.

The study

In the study, Trommelen et al. measured the protein and amino acid uptake after ingesting a post-exercise protein dose. The subjects (36 healthy young men) performed a resistance training bout and received a shake containing 0g, 25g or 100g milk protein. The investigators used labelled amino acids, which allowed them to measure their levels in blood at different time points. They also used muscle biopsies at different time points to measure amino acid uptake.

The results

This study showed that a) the release of amino acids in blood, b) the uptake of amino acids into tissues and c) the rate of muscle protein synthesis all increased proportionally with the protein dose, meaning that the effect of 25g of protein was greater than 0g of protein, and the effect of 100g of protein was greater than both 0g and 25g. The researchers also found that the ingested amino acids were available in circulation for about 5 hours with 25g protein and at least 12 hours after 100g protein.

As a reminder, this study used milk protein, which is digested slowly compared to other proteins such as whey. A potential concern would be that amino acids coming from rapidly digestible proteins would be oxidised before the muscles get a chance to use them. However, based on available evidence, the researchers concluded that these results can be applied to rapidly digestible proteins.

Is protein distribution dead?

This study shows that consuming large doses of protein after resistance training can be more effective at generating an anabolic response than consuming a more traditional moderate amount.

While some athletes implementing this approach might still consume moderate amounts of protein in the rest of their meals, some may choose to reserve the bulk of their daily protein to the post-exercise window. For example, those following a restricted eating window (commonly known as “intermittent fasting”).

However, this does not mean that everyone should consume 100g of protein post-exercise. The results may vary based on the training protocol, protein source and athlete’s biological characteristics (e.g. sex, age, training level, digestion, gut microbiome).

The choice of how much protein to have after resistance training also depends on practical considerations. For example, it might not be practical or comfortable to consume that much protein in the form of whole foods (e.g. meat, fish, eggs, or even worse, plant-based protein sources) if the athlete is going to bed or has another training session shortly after the strength session. This issue could be prevented by using a rapidly digested protein source such as whey protein isolate.

Last but not least, it is important to note that athletes who have health conditions, particularly those involving protein metabolism, should talk to their physician before testing this approach.

Protein distribution remains to be an effective way of maximising muscle growth and/or minimising muscle breakdown for athletes and recreational exercisers.

References

1. Trommelen J, van Lieshout GAA, Nyakayiru J, Holwerda AM, Smeets JSJ, Hendriks FK, et al. The anabolic response to protein ingestion during recovery from exercise has no upper limit in magnitude and duration in vivo in humans. Cell reports Med. 2023 Dec;4(12):101324.

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