Green tea inhibits breakdown of fast muscle fibres during long-term inactivity

A supplement containing a couple of hundred milligrams of green tea extract may protect the muscle fibres of strength athletes from breaking down if they don’t use their muscles for a lengthy period. Researchers at West Virginia University in the US suggest this in an animal study they published in the Journal of Applied Physiology about experiments they did with old lab rats.

Study
The researchers set their experiment up in such a way that their lab animals were unable to use one hind leg for two weeks, and gave some of the rats green-tea extract every day. The human equivalent of the dose they used would be 600-800 mg green tea extract per day.

At the end of the two weeks the researchers let the rats use their hind leg for the next two weeks.

During both periods the researchers studied the effect of the supplementation on the muscles in the hind leg.

Results
The supplementation had no effect on the soleus muscle, but did have an effect on the plantaris. Most of the muscle fibres in the soleus are slow ones, whereas those in the plantaris are fast ones. Strength athletes’ training develops mainly their fast muscle fibres. During the period that the rats were not able to use their hind leg [HLS], the supplement inhibited the breakdown of muscle tissue in the plantaris.

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Green tea supplementation did not speed up the recovery of the muscles during the recovery period.

The figure below shows how the extract reduced muscle breakdown in the plantaris during the period of inactivity. The researchers found less protein carbonyls and less 8-iso-PGF2-alpha in the muscles of the rats that had been given green tea. That is an indication of reduced activity of free radicals.

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The supplementation had no effect on muscle mass when the rats started to use the muscles in their hind leg again. Nevertheless, the researchers discovered that the green tea extract stimulated the transformation of stem cells into muscle cells in both the soleus and the plantaris. But the effect was apparently not strong enough to speed up the growth of muscle tissue.

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Conclusion
“These data suggest that muscle recovery following disuse in aging is complex”, the researchers wrote. “Although satellite cell proliferation and differentiation are critical for muscle repair to occur, green tea-induced changes in satellite cell number is by itself insufficient to improve muscle recovery following a period of atrophy in old rats.”

Green tea extract attenuates muscle loss and improves muscle function during disuse, but fails to improve muscle recovery following unloading in aged rats.

Abstract

In this study we tested the hypothesis that green tea extract (GTE) would improve muscle recovery after reloading following disuse. Aged (32 mo) Fischer 344 Brown Norway rats 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. The rats were given GTE (50 mg/kg body wt) or water (vehicle) by gavage 7 days before and throughout the experimental periods. Compared with vehicle treatment, GTE significantly attenuated the loss of hindlimb plantaris muscle mass (-24.8% vs. -10.7%, P < 0.05) and tetanic force (-43.7% vs. -25.9%, P <0.05) during HLS. Although GTE failed to further improve recovery of muscle function or mass compared with vehicle treatment, animals given green tea via gavage maintained the lower losses of muscle mass that were found during HLS (-25.2% vs. -16.0%, P < 0.05) and force (-45.7 vs. -34.4%, P < 0.05) after the reloading periods. In addition, compared with 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%) muscles after HLS. This green tea-induced difference was not transient but was maintained over the reloading period for plantaris (-45.6% vs. -21.5%, P <0.05) and soleus muscle fiber cross-sectional area (-38.7% vs. -10.9%, P <0.05). GTE increased satellite cell proliferation and differentiation in plantaris and soleus muscles during recovery from HLS compared with vehicle-treated muscles and decreased oxidative stress and abundance of the Bcl-2-associated X protein (Bax), yet this did not further improve muscle recovery in reloaded muscles. These data suggest that muscle recovery following disuse in aging is complex. Although satellite cell proliferation and differentiation are critical for muscle repair to occur, green tea-induced changes in satellite cell number is by itself insufficient to improve muscle recovery following a period of atrophy in old rats. PMID: 25414242 [PubMed - in process] PMCID: PMC4312851 [Available on 2016-02-01] Source: http://www.ncbi.nlm.nih.gov/pubmed/25414242 

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