Thursday, November 27, 2014

Green Tea for Muscle Protection? GTE Increases Satellite Cell Proliferation & Differentiation, Slows Disuse-Related Atrophy, Does not Promote Hypertrophy in Aged Rodents

Green tea as a magical muscle preservative for injured athletes?
"GTE increased satellite cell proliferation and differentiation, decreased oxidative stress and the abundance of Bax, a proapoptotic protein" (Alway. 2014) - that's the initially exciting result of a recent study from the West Virginia University School of Medicine and Abbott Laboratories. What is not exactly as exciting, though, is how the sentence continues, i.e. "yet this did not further improve muscle recovery in reloaded muscles" (Alway. 2014).

Sounds contradictory, right? Well, before we get deeper into the discussion of the results, let's briefly recap how Alway et al. arrived at these insights, i.e. how exactly the experiment looked like and which experimental evidence it generated.

The scientists from the West Virginia University School of Medicine tested the hypothesis that green tea extract (GTE) would improve muscle recovery after reloading following disuse. In men and women "muscle disuse" would equal lying around in bed or on the sofa all day. In rodents it was simulated by an initial 14-day period of hindlimb suspension (HLS) and a subsequent period of reloading (recovery).
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The subjects the researchers use were Fischer 344 Brown Norway rats who were randomly assigned to receive either 14 days of hindlimb suspension (HLS) or 14 days of HLS, followed by normal ambulatory function for 14 days (recovery). Additional animals served as cage controls.
Figure 1: Muscle wet weight. Muscle wet weight was obtained in hindlimb muscles of cage control animals, after 14 days of hindlimb suspension group (HLS), or after 14 days of hindlimb suspension followed by 14 days of reloading (Recovery). And Ex vivo isometric force. A. Maximal tetanic force obtained at a frequency of 100Hz, or B. Peak twitch force (PT) of the plantaris muscle was measured in cage control rats, after 14 days of hindlimb suspension (HLS) or after 14 days of hindlimb suspension followed by 14 days of reloading (Recovery | Alway. 2014).
Both active treatment groups were given green tea extracts at a dosage of 50 mg/kg body weight - that's roughly 600-750mg of green tea extract per day. The control group received pure water, instead.
As you can see in Figure 1, the animals that received the green tea supplement exhibited a significantly attenuated loss of hindlimb plantaris muscle mass and tetanic force during.
In addition, compared to the vehicle treatment, GTE attenuated muscle fiber cross sectional area loss in both plantaris (-39.9% vs. -23.9%, p<0.05) and soleus (-37.2% vs. -17.6%) after HLS. This green tea-induced difference was not transient but it was maintained over the reloading period.

Increased muscle retention = increased fat loss!?

That's particularly interesting in view of the fact that the changes in body weight did not differ between the green tea and water group (see Figure 2).
Figure 3: Relative reductions in total body body weight in the two groups (Alway. 2014)
Why? Well it signifies that there is a significantly reduced negative impact on the body composition, with green tea. That does not change, though, that "GTE failed to further improve recovery of muscle function or mass as compared to vehicle treatment" (Alway. 2014)
This begs the question - would you recommend GTE? As a muscle preserver during periods, where you cannot workout, yes. The way it conserved the muscle mass in the study at hand should help help you to get back to the grind after a debilitating exercise, even if the recovery in the study at hand seemed to be identical in both groups. The green tea induced increase in satellite cell proliferation and differentiation, as well as the decreased oxidative stress and the abundance of the catabolic protien Bax, on the other hand, is probably not going to have a significant effect as long as you are still able to move, because exercise alone will induce more pronounced benefits in these domains.

Figure 4: Changes in body composition in a study w/ obese subjects comparing GTE to resistance training and a combination of both green tea extract and resistance training on body comp. (Cardoso. 2013)
Plus: We should not forget that the effects were observed in old rats and thus in a model of a population group that appears to benefit from antioxidant supplementation more than young(er) people. If you don't belong to the corresponding group of human beings whose muscles are particular prone to oxidative damage and suffer from a reduced ability to adapt to exercise induced stress, the effects remain questionable. In obese individuals green tea has yet been shown to promote the beneficial effects of exercie on body composition (Cardoso. 2013) - the risk that it a low dose of GTE does anything but good, does thus appear to be very small; and that's true for the benefits for athletes, too - at least according to previously reported results | Comment on Facebook!
  • Alway et al. "Green tea extract attenuates muscle loss and improves muscle function during disuse, but fails to improve muscle recovery following unloading in aged rats." Journal of Applied Physiology (2014). Ahead of print.
  • Cardoso, Gabrielle Aparecida, et al. "The effects of green tea consumption and resistance training on body composition and resting metabolic rate in overweight or obese women." Journal of medicinal food 16.2 (2013): 120-127.