[Objective]The influence of electroacupuncture (EA) stimulation on physical inactivity is not clear. This study aimed to investigate the effects of EA on the recovery of mouse soleus muscle atrophy induced by hindlimb suspension (HS).
[Methods]We used 8-week-old male ICR mice (n = 20). The mice were divided into 4 groups:the No treatment group (NT, n = 5), HS group (HS, n = 5), Control group (CT, n = 5), and Reloading-with-EA-stimulation group (EA, n = 5). HS mice were suspended for up to 14 days. CT and EA mice were reloaded for an additional 14 days after the HS for 14 days. The HS method used a modified version of an apparatus used in a previous study. EA mice received EA every other day immediately after reloading and were stimulated in the triceps surae muscle at 10 Hz for 30 min with a stainless steel needle. The weight, muscle fiber area size and number of macrophages in the soleus muscle were analyzed.
[Results]The number of skeletal muscle macrophages was increased significantly in EA mice compared with that in CT mice (P < 0.01). The soleus muscle weight and muscle fiber cross-sectional area were decreased in HS mice compared with NT mice (P < 0.01). However, the muscle weight of EA and CT mice increased significantly compared with that of HS mice (P < 0.01). In addition, the muscle weight of EA mice was significantly higher than that of CT mice (P < 0.01), without a significant difference in muscle fiber cross-sectional area between CT and EA mice.
[Conclusion]These results indicate that EA was effective in facilitating the recovery of skeletal muscle atrophy in mice. In addition, resolution of the skeletal muscle atrophy suggested the satellite cell activation by macrophages, because macrophages invaded the skeletal muscle after EA stimulation.

Mitochondria activation factor (MAF) which is high-molecular weight polyphenol contained in black tea and oolong tea can increase the mitochondrial membrane potential. MAF supplementation to mice facilitates endurance running performance after 9-week endurance training and muscle hypertrophy induced by synergist ablation. In this study, we examined the effect of oral MAF supplementation on overall physical fitness (expressed as physical fitness age) in physically active middle-aged and older women. This study is a randomized double-blind placebo-controlled trial implemented between January and May 2019 at three fitness facilities in Ibaraki, Japan. Seventy middle-aged women aged 55 to 69 years were randomly assigned into placebo (n = 35) and MAF groups (n = 35). The placebo participants took cornstarch-containing capsules, and the MAF participants took MAF-containing capsules twice a day for 80 days consecutively. During the intake period, all participants were instructed to follow 30-min circuit training program at least twice a week. Physical fitness age was computed with eight physical fitness items assessing upper-extremity muscle strength, locomotion, and postural change. The physical fitness age decreased by 1.48 years (95% confidence interval [CI]: -2.66, -0.30) in the placebo group and 3.01 years (95% CI: -4.16, -1.86) in the MAF group. The reduction was greater in the MAF group, but did not reach statistical significance (p = 0.06). The combination of 80-day of MAF intake and circuit exercise showed beneficial results. However, our results did not indicate clear effects on physical fitness age because of low statistical power. Further studies are necessary to reveal the effects of MAF supplementation.