Few studies explore the associations between body fat percentage (BFP) prediction and evaluation indicators for Chinese with normal-weight obesity. We aimed to explore convenient and cost-free BFP evaluation indicators to routinely monitor BFP status in Chinese patients with normal-weight obesity. Participants (N = 164) were divided into three groups according to body mass index (BMI) and BFP: normal-weight lean, normal-weight obese, and overweight and obese. Differences in body composition and circumference were compared to examine the relationship between BFP and circumference, determine a simple evaluation indicator reflecting BFP, and identify cutoff values for normal-weight obesity circumference. Significant differences in body composition and circumference were observed among the three groups. The correlation between thigh/height, hip/height, (hip + waist)/height, and BFP was stronger than that with BMI. The (hip + waist)/height ratio was the indicator most reflective of BFP (95% confidence interval: 3.004–9.018, p = 0.013), and a ratio above 1.115 (95% confidence interval: 0.936–0.992, p < 0.001) was predictive of normal-weight obesity. Furthermore, we suggest that the upper value for a normal BMI in Chinese individuals be lowered to 23.4 kg/m² (95% confidence interval: 0.984–0.999, p < 0.001). The (hip + waist)/height ratio can be used with body mass index for a more accurate evaluations of BFP abnormalities and health risks.

Subacromial bursitis (SAB) is the major source of pain in rotator cuff disease. Although multiple investigations have provided support for the role of inflammatory cytokines in SAB, few have focussed on the use these cytokines in the treatment of SAB. The aim of the present study was to observe the therapeutic efficacy of lentivirus‑mediated RNA interference (RNAi) on carrageenan‑induced SAB by injecting lentivirus‑tumor necrosis factor (TNF)‑α‑RNAi expressing TNF‑α small interfering (si)RNA. Using screened siRNA segments, an siRNA was designed. A lentivirus vector expressing siRNA was established and packed as lentivirus particles. A lentivirus that expressed the negative sequence was used as a lentivirus‑negative control (NC). The carrageenan‑induced SAB model was established in 32 male Sprague‑Dawley rats. The modeled rats were randomly assigned to four groups: Lentivirus‑RNAi treatment group, lentivirus‑NC group, SAB group and phosphate‑buffered saline (PBS) blank control group. The lentivirus was injected (1x10(7) transducing units) into the subacromial bursa of the rats in the lentivirus‑RNAi group and lentivirus‑NC group, whereas 100 µl PBS was injected at the same site in the SAB group and the PBS blank control group. At 5 weeks following injection, the animals were sacrificed and venous blood was obtained. The effect of TNF‑α interference and the expression of inflammatory cytokines were determined by reverse transcription‑quantitative polymerase chain reaction, western blotting, hematoxylin and eosin staining, Van Gieson's staining and immunofluorescence. The expression of TNF‑α was decreased in the lentivirus‑TNF‑α‑RNAi group compared with that in the SAB group. Morphological observations revealed that the number of inflammatory cells were reduced and damage to tendon fibers was attenuated in this group, suggesting that the downregulation of the protein expression levels of TNF‑α‑associated nuclear factor‑κB, matrix metalloproteinase (MMP)1, MMP9, cyclooxygenase (COX)‑1 and COX‑2 may exert a therapeutic effect on inflammation of the SAB caused by rheumatoid arthritis. It was also found that the expression of stromal cell‑derived growth factor‑1 was downregulated in the lentivirus‑TNF‑α‑RNAi group. Therefore, the present study demonstrated that lentivirus‑mediated TNF‑α RNAi effectively inhibited the inflammatory response in SAB, and that injection of a lentivirus vector into the affected region is an effective way of achieving RNAi in vivo.

Although evidence suggests that intramuscular fat infiltration may influence muscle strength, the precise mechanisms remain unclear. This study aimed to determine whether intramuscular fat infiltration affects muscle mechanical properties during contraction and whether these mechanical properties mediate the relationship between intramuscular fat infiltration and muscle strength. Seventy-nine healthy older women aged 75.1 ± 6.8 years were included in this study. The echo intensity (EI) of the vastus lateralis (VL) was measured as an intramuscular fat infiltration index using B-mode ultrasonography. Maximum voluntary isometric contraction strength (MVIC) was assessed using a dynamometer. The VL shear elastic modulus (G), a mechanical property index, was measured using ultrasound shear wave elastography under various muscle contraction conditions, at rest and at 15%, 30%, and 45% MVIC (G0, G15, G30, and G45). To evaluate the degree of increase in the shear elastic modulus with increasing muscle contraction intensity, the slope of the regression line (Gslope) between muscle contraction and shear elastic modulus was calculated for each participant. The results showed that EI was significantly associated with G30 and G45 but not with G0 or G15. The EI can significantly explain the inter-individual differences in Gslope. Mediation analysis revealed that the effect of EI on MVIC through Gslope was significant (indirect effect = −0.31, 95% confidence interval (−0.57, −0.12)). These findings suggest that a greater EI is associated with a lower G during muscle contraction. Furthermore, our results show that the relationship between EI and MVIC is mediated by Gslope.

[Purpose] We aimed to explore the effects of the COVID-19-induced lockdown in Beijing. [Participants and Methods] We distributed a web-based questionnaire survey among 1,029 Beijing citizens to inquire about their physical condition, living habits, and physical activity before and during home isolation. [Results] In the context of forced home isolation due to COVID-19, both males and females reported reductions in daily steps and weekly exercise time and significant increases in daily physical activity time and daily sitting time. The proportions of smokers, patients with metabolic syndrome, and patients with internal diseases were higher in males than in females; females had lower daily step counts and spent more time sitting. [Conclusion] The COVID-19 lockdown affected the physical condition, living habits, and physical activity of both males and females; females were more affected than males. People should be cognizant of the various effects of COVID-19 lockdowns on the body. We recommend a reasonable diet and appropriate home exercise. There is a need to develop training methods and evaluation tools for home exercises in COVID-19 lockdowns.