Effects of Coffee Components on Muscle Glycogen Recovery: A Systematic Review

Introduction

This is an interesting new study demonstrating that there may be additional benefits for implementing the "Anabolic Window". Although there are some misconceptions behind it, which I will first clear up. You do not need to eat or drink immediately after a workout in order to recover and make progress/gains, as long as you have had a protein feeding less than 2.5 hours before and within 2 hours after your workout. You will not reach a catabolic state, assuming you are consuming enough protein. BUT, there have been previous studies showing benefits to specific post-workout nutrition protocols, in order to optimize training-related muscular adaptations. Firstly, consuming 40g of whey post-workout enables an increase in muscle protein synthesis over baseline levels, thus leading to increased myofibril growth. Secondly, post-workout carbohydrate (CHO) intake causes increased insulin release. Combining both leads to increased anabolism. As you can see, the "Anabolic Window" does in fact exist but is not required. I will now be discussing the findings of a new study which also adds to the benefits of post-workout nutrition.

Background Info

As you know, coffee is one of the most widely consumed beverages in the world, but many don't know that it can improve insulin sensitivity and stimulate glucose uptake in skeletal muscle when adequate carbohydrate intake is observed. Let’s delve into glycogen resynthesis which happens in 2 phases. The Early Phase (0-60 minutes) is where ‘insulin-independent’ resynthesis is high and Late Phase (1 hour to 48 hours) is where ‘insulin-dependent” resynthesis is low. The rate of post-exercise muscle glycogen resynthesis depends on many factors, such as the quantity of muscle glycogen that was depleted, the amount of CHO ingested, the rate of gastric emptying and intestinal glucose uptake, and the insulin-stimulated muscle glucose uptake and subsequent conversion to glycogen.

Beneficial Compounds in Coffee

Caffeic Acid: Increases glucose uptake in the absence and then promotes insulin secretion. 5' adenosine monophosphate-activated protein kinase or AMPK is also activated and contributes to the energy status of cells which leads to increased energy expenditure and plays a role in cellular energy homeostasis. This suggests that exercise + caffeic acid may have additive effects on the desired outcome of the training stimulus because of the non-insulin mediated processes going on.

Cafestol: Passes poorly through coffee filters and is in its highest concentration when the coffee is made via French press. This compound has showed insulin sensitivity benefits comparable to Rosiglitazone (antidiabetic drug). This positive interaction was mainly due to glucose uptake mostly into skeletal muscle. So, Cafestol may be beneficial in both the prevention of type 2 diabetes and in post-workout muscle glycogen recovery.

Chlorogenic Acid: Major determinant in the flavor of the coffee. This review suggested no real significant interaction between this and glycogen/glucose/insulin. But, it makes coffee taste like coffee so it is the most important compound in coffee.

Caffeine: Moderate central nervous system stimulant. Studies can’t seem to agree on post-exercise recovery in this review. It seems like most studies note some fluctuation of glucose with little to no change in insulin. But, most of studies come to similar conclusions that caffeine ingestion does increase glucose uptake because of a combination of the associated polyphenols and phytochemicals.

Conclusion

Ok. So, I get this is a lot to take in. I love this little review because I believe that the “post workout recovery window” is way more important than most people think. Here is why:

Intense resistance training stimulates a ton of contraction dependent, non-insulin mediated translocation of certain transport proteins post exercise. Mainly GLUT4 which is the insulin-regulated glucose transporter found primarily in adipose tissue and striated muscle. This is just something that happens in response to heavy lifting. These transporters help to uptake glucose WITHOUT the presence of insulin. This is a transient phenomenon that does not last very long after the cessation of the stimulus. Along with this, caffeine stimulates activation of CAMK, an enzyme that uptakes glucose into muscle cells without the help of other glucose transporters. Within the muscle cells themselves, caffeine stimulates more phosphorylation of Akt. Akt is an enzyme that plays a huge role in glycogen resynthesis along with a handful of other processes.

In summary, even though the literature is back and forth on the topic, we can assume using other research and some of the above-mentioned exercise metabolism principals that coffee does create a better environment for post exercise glycogen resynthesis than post exercise carbohydrate ingestion alone.

As far as how much? Who knows. Pre-exercise, 3-6mg/kg of bodyweight ingested one hour before exercise seems to show the most performance benefit for training and competition. Anything less than that doesn’t enhance performance and anything over 9mg/kg seems to start to decrease performance. I think a good place to start would be 3mg/kg pre-workout then the same immediately post workout with CHO ingestion.

I am sure this will start an argument (because it is fitness on the internet, and no other facet of humanity that seems to have harder lines of zealot war parties critiquing other people’s chosen form of recreational free weight resistance training and dietary worship strategy), but I think this is relevant stuff for those doing higher frequency training or lower frequencies with higher rates of glycogen depletion directed work.

Cool stuff right? Now go eat. Your anabolic window is slamming shut.

Discussion

• Do you think decaffeinated coffee will have the same benefits?
• Will you be taking advantage of these new found benefits of coffee?

References

Loureiro, L. M., Reis, C. E., & Costa, T. H. (2018). Effects of Coffee Components on Muscle Glycogen Recovery: A Systematic Review. International Journal of Sport Nutrition and Exercise Metabolism, 1-31. doi:10.1123/ijsnem.2017-0342