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The key to getting bigger and stronger may not involve calculating the right ratio of carbs to protein for muscle growth post-workout. And forget the immediate anabolic window for replenishing muscle glycogen stores following a workout. We found research that challenges the exercise science dogma of an immediate carb-centric post-workout fueling. In this blog, we will explore better strategies to optimize muscle protein synthesis and muscle glycogen. Read below to see how InsideTracker data and recommendations can help you reevaluate your post-workout food no matter your dietary lifestyle choice or exercise regime by monitoring key biomarkers.
Does muscle protein synthesis really need carbs? Think twice about guzzling a sugary drink post-workout
Previous studies suggest that combining carbs with protein stimulates muscle protein growth. This may be due to a higher energy intake combined with increased insulin release due to carb consumption. Yet, whether or not circulating insulin regulates muscle protein synthesis is up for debate.
A couple of studies explored rates of muscle protein synthesis at different levels of circulating insulin. However, in healthy, young adults, it is suggested that insulin is more permissive instead of regulatory in the stimulation of muscle protein synthesis. Meaning, the anabolic(i.e., muscle growth) effects of protein are sufficient enough to stimulate muscle protein synthesis when there is low insulin. Insulin is not as anabolic as protein even though it does help suppress protein breakdown.
A study using 24 older men contradicts the mainstream perspective on post-workout fueling that focuses on a greater ratio of carbs to protein. The men were randomized into two different groups: one eating carbs (40g) and protein (20g) and the other eating protein (20g) only. Following blood samples and muscle biopsies, the group that consumed carbs and protein had more of the protein incorporated into their muscle within two hours. However, after 6 hours, there was no difference in muscle protein-bound between both groups.
The protein-only group had a sufficient amount of protein to stimulate muscle protein synthesis – and the added benefit of no insulin spike. This prevents the rapid glucose uptake by tissues and subsequent drop in blood glucose that leads to a “sugar crash” – the fatigue experienced after consuming a large amount of carbs. The study concluded that additional carb consumption may accelerate post-prandial (after meal) muscle protein synthesis, but it is not required for optimization of muscle protein growth.
One study found that carbs only prevent protein breakdown when not enough protein is consumed. As long as you ingest an adequate amount of protein (~25 g), which does not have to be immediately following a workout, you do not need to pour on the sugar. The carbs are not needed to process the protein. In fact, frequent, high doses of quality protein may generate the greatest anabolic effect.
As we see, that post-workout sugary drink does not add anything to protein in post-workout feeding. In fact, following resistance training, women may require more protein for muscle growth to achieve the same anabolic effect as men due to a difference in how sex hormones influence muscle protein metabolism.
Summary: Post-workout feeding does not require carbs for optimal muscle protein synthesis as long as protein intake is adequate following a workout. A need for higher protein consumption following resistance training is especially important in women.
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