No carbs after your workouts? Less muscle recovery and growth...
Physical exercise stimulates the muscle cells to burn more fats and to produce more mitochondria. Can athletes strengthen these processes by following a low-carb diet? No, write sports scientists at Liverpool John Moores University in an article in Medicine & Science in Sports & Exercise. A low-carb diet might actually reduce athletes' muscle recovery and growth...
The researchers did an experiment with ten male runners, which they repeated on two occasions. On both occasions the participants trained twice in one day: after breakfast the men did an intensive interval training workout in the morning, and early in the afternoon the men ran at a moderately intensive pace for one hour.
On both occasions the men breakfasted on carbohydrates, proteins and fats. On one of the occasions the participants were given carbohydrate-rich food for the rest of the day; on the other they were fed only low-carb food.
The researchers took small samples of muscle tissue from the men's leg muscles before and after the training sessions, and then analysed these.
When the participants had eaten low-carb food after their training sessions, the researchers found less glycogen in their muscle cells. Despite this they did not observe more active AMPK in the muscle cells. That means that the low-carb diet did not result in more fat burning and it didn't stimulate the production of mitochondria either.
In addition, the low-carb diet inhibited the activity of the anabolic signal molecule p70S6K. That might mean that a low-carb diet weakens anabolic processes.
"We provide novel data by concluding that post-exercise high fat feeding has no modulatory affect on AMPK-alpha2 activity or the expression of those genes associated with regulatory roles in mitochondrial biogenesis", the researchers wrote. "Furthermore, although post-exercise high fat feeding augmented the expression of genes involved in lipid transport and oxidation, we also observed a suppression of p70S6K1 activity despite sufficient post-exercise protein intake."
"This latter finding suggests that post-exercise high fat feeding may impair the regulation of muscle protein synthesis and post-exercise muscle remodelling, thereby potentially causing maladaptive responses for training adaptation if performed long-term."
"Future studies should now examine the functional relevance of the signalling responses observed here, not only in terms of acute muscle protein synthesis but also the chronic skeletal muscle and performance adaptations induced by long-term use of this feeding strategy."
Just a niggle
Athletic low-carbers notice that in real life the body needs several weeks to fully adjust to a low-carb diet. The participants in the experiment had not undergone this process of adaptation. So it might just be that the researchers would have obtained different results if they had performed their experiment on people who had become used to a low-carb diet.
Med Sci Sports Exerc. 2016 Nov;48(11):2108-2117.
Study: low carb + strength training = big fat loss, no lean body mass loss 13.02.2011
Low-carb protein diet causes muscles to grow without training 13.08.2010
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