During sleep, protein synthesis rates are normally very low. Professor Luc van Loon from Maastricht University in the Netherlands argued that sleep is a period of 7-10 hours that is normally not utilized to adapt to training. Peter Res in van Loon's research group performed a study a few years ago that showed that providing protein before bed time increased protein synthesis during the night. This week, the same reserach group published a new paper in the Journal of Nutrition that demonstrated that this can also result in strength gains over time. This is potentially very important and exciting news for serious athletes who are looking to optimize training adaptation. Lets have a look at some of the details of the study and see what practical recommendations come out of this.
The early study
In initial study by Peter Res published in Medicine and Science in Sports and Exercise in 2012 athletes performed resistance exercise at 8PM, then consumed a protein and carbohydrate drink immediately after the workout (20 grams of protein and 60 grams of carbohydrate) and went to bed at 11:30 PM after consuming 40 grams of protein or placebo. Protein synthesis was measured and was found to be significantly higher with the protein ingestion compared with placebo.
The new study
The new study was a follow up from this. The observation that protein synthesis is high with protein intake before sleep does not automatically mean that you will gain muscle or get stronger. Therefore, 44 young men enrolled in a 12-week strength training program. The training took place in the evening 8-9PM or 9-10PM and was strictly controlled.
The particpants were randomly divided into two groups. One group received a protein supplement containing 28 g of protein and 15 g of carbohydrate every night before sleep. The other group received a non-caloric placebo. (In this study the protein used was a combination of casein and casein hydrolysate in a 1:1 ration, thus a slow as well as a fast source of amino acids).
As expected, muscle strength increased after resistance exercise training in both groups but the new finding was that strength increased to a greater extent in the protein group than in the placebo group. In addition to this, after protein ingestion muscles were also larger. The cross-sectional area of the quadriceps muscle increased in both groups over time but the increase was greater in the protein group.
Conclusion and practical implications
Therefore the authors concluded that protein ingestion before sleep represents an effective dietary strategy to increase muscle mass and strength gains during resistance exercise training. Dr Tim Snijders, first author of the paper mentioned to me that "this is the first time that it is hown that sleep is an effective period to imporve changes in muscle mass and strength, even when total daily protein intake is relatively high (1.3 g/kg).
It must be noted that the amount of protein ingested (28 grams) in this study is a fairly large amount of protein to ingest just before going to sleep. It is the equivalent of 800ml of milk, 4 large eggs or a small chicken breast.
A lot still to discover
Clearly we still have a lot to learn. For example, it is not known if smaller amounts of protein can also be effective. It is also not known what the optimal protein is to stimulate proteins synthesis, increases in muscle mass and strength. We dont know whether the added carbohydrate had an effect and we dont know what the optimal macronutrient composition is of a bed time drink or meal. We dont even know whether there is a difference in liquids and solid food forms. Tim Snijders adds "Future research will also tell us whether supplementing just before sleep is more effective tha supplementing at any other time point during the day". This is of course an important point because the control condition in this study was no protein supplement.
This is a new area of research that is promising but also relatively unexplored. The studies described here by Prof van Loon and his team are heroic to say the least and are amongst the most difficult to perform studies in human physiology. The findings are exciting and I am looking forward to future studies that will help us to optimize the adaptations to training and getting more return for all the hard work done in training.
T Snijders, PT Res, JSJ Smeets, S van Vliet, J van Kranenburg, K Maase, AK Kies, LB Verdijk, LJC van Loon. Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men. J Nutr In press Apr 29, 2015