|The kids who were the subjects in the study at hand didn't lift. They ran and cycled and still ended up in a positive nitrogen balance - thanks to post-workout protein supplementation.|
In an upcoming issue of the Journal of Applied Physiology researchers from the Nestle Research Center are now about to publish what I believe is a unique study investigating the net protein balance (=synthesis minus breakdown) over 8h and 24h after the workout in response to the ingestion of different amounts of whey + casein (at a 1:4 ratio) immediately after a standardized running and cycling intervention (Moore. 2014)
In contrast to "the average" protein synthesis study, the study at hand didn't just use an unusual subject group consisting of 6 female and 7 male kids (mean age 11.7 years), the type of exercise and the method the scientists used to determine the usefulness of the low (0.75g/100ml) and high (1.5g/100ml) protein beverages were different as well.
|Figure 1: Graphical overview of the study design (Moore. 2014)|
|Overview of the total energy and macronutrient intake (Moore. 2014)|
Aside from the energy and macronutrient profiles of the test beverages, the 24h controlled diets were supplied as isoenergetic breakfast and lunch meals (consumed within the laboratory providing ~11 and 40% of 24h energy intake, respectively) and dinner meals (consumed outside the laboratory providing ~35% of 24h energy intake) with the remaining ~14% of energy coming from the test beverages. The breakfast, lunch, and dinner meals were also isoprotein and provided ~15, 45, and 40% of the 24h food protein intake, respectively, with the test beverages providing a variable amount of protein in addition to the meal protein intake.
|Figure 2: Protein breakdown, synthesis and net protein balance over 24h (Moore. 2014)|
Last but not least it may be important to mention that the total protein intake was (a) not extremely different between the three groups (see figure in "tight dietary control" box) and that (b) it was actually below the kids habitual protein intake of 1.56g/kg which would suggest that it is unlikely that some sort of accommodation effect may occur over time.
- de Oliveira, Erick Prado, and Roberto Carlos Burini. "The impact of physical exercise on the gastrointestinal tract." Current Opinion in Clinical Nutrition & Metabolic Care 12.5 (2009): 533-538.
- Millward, DAVID J., et al. "Effect of exercise on protein metabolism in humans as explored with stable isotopes." Federation proceedings. Vol. 41. No. 10. 1982.
- Mitchell, Cameron J., et al. "Acute Post-Exercise Myofibrillar Protein Synthesis Is Not Correlated with Resistance Training-Induced Muscle Hypertrophy in Young Men." PloS one 9.2 (2014): e89431.
- Moore et al. "Post-exercise protein ingestion increases whole body net protein balance in healthy children." J Appl Physiol (October 23, 2014). Article in press.