Bone diseases are usually caused by abnormal metabolism and death of cells in bones, including osteoblasts, osteoclasts, osteocytes, chondrocytes, and bone marrow mesenchymal stem cells. Mitochondrial dysfunction, as an important cause of abnormal cell metabolism, is widely involved in the occurrence and progression of multiple bone diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma. As selective mitochondrial autophagy for damaged or dysfunctional mitochondria, mitophagy is closely related to mitochondrial quality control and homeostasis. Accumulating evidence suggests that mitophagy plays an important regulatory role in bone disease, indicating that regulating the level of mitophagy may be a new strategy for bone-related diseases. Therefore, by reviewing the relevant literature in recent years, this paper reviews the potential mechanism of mitophagy in bone-related diseases, including osteoarthritis, intervertebral disc degeneration, osteoporosis, and osteosarcoma, to provide a theoretical basis for the related research of mitophagy in bone diseases.

Peripheral nerve injury (PNI) is a clinical problem with high morbidity that can cause severe damage. Surgical suturing or implants are usually required due to the slow speed and numerous factors affecting repair after PNI. An autologous nerve graft is the gold standard for PNI repair among implants. However, there is a potential problem of the functional loss of the donor site. Therefore, tissue-engineered nerve biomaterials are often used to bridge the gap between nerve defects, but the therapeutic effect is insufficient. In order to enhance the repair effect of nerve biomaterials for PNI, researchers are seeking to combine various stimulation elements, such as the addition of biological factors such as nerve growth factors or physical factors such as internal microstructural modifications of catheters and their combined application with physical stimulation therapy. Physical stimulation therapy is safer, is more convenient, and has more practical features than other additive factors. Its feasibility and convenience, when combined with nerve biomaterials, provide broader application prospects for PNI repair, and has therefore become a research hot spot. This paper will review the combined application of physical stimulation and biomaterials in PNI repair in recent years to provide new therapeutic ideas for the future use of physical stimulation in PNI repair.

Osteoporosis (OP) is a chronic bone disease characterized by decreased bone mass, destroyed bone microstructure, and increased bone fragility. Accumulative evidence shows that extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs) (MSC-EVs), especially exosomes (Exos), exhibit great potential in the treatment of OP. However, the research on MSC-EVs in the treatment of OP is still in the initial stage. The potential mechanism has not been fully clarified. Therefore, by reviewing the relevant literature of MSC-EVs and OP in recent years, we summarized the latest application of bone targeted MSC-EVs in the treatment of OP and further elaborated the potential mechanism of MSC-EVs in regulating bone formation, bone resorption, bone angiogenesis, and immune regulation through internal bioactive molecules to alleviate OP, providing a theoretical basis for the related research of MSC-EVs in the treatment of OP.

Introduction: This study aims to establish normal reference values of peak oxygen uptake (VO_2peak) for cardiorespiratory fitness (CRF) in Chinese adults using cardiorespiratory exercise testing (CPET). Methods: A cross-sectional study was done in four communities, two in the North (Beijing) and two in the South (Hezhou, Guangxi) of China from 1 January 2017 to 31 December 2018, with one urban and one rural in each region. Out of 1642 participants screened, 1114 were eligible and completed CPET using a cycle ergometer (Ergosana320F) without abnormal ECG and were included in the analysis. The 2nd and 98th percentiles of $\stackrel{·}{\mathrm{V}}$O_2peak were used as the lower and upper limits of the normal reference values. Results: Significant difference in mean $\stackrel{·}{\mathrm{V}}$O_2peak was shown between men (27.0 mL·min⁻¹·kg⁻¹) and women (23.7 mL·min⁻¹·kg⁻¹). The mean $\stackrel{·}{\mathrm{V}}$O_2peak decreased with age in both sexes, from 35.8 mL·min⁻¹·kg⁻¹ in age 20–29 years to 20.5 mL·min⁻¹·kg⁻¹ in 70–79 years in men and from 29.2 mL·min⁻¹·kg⁻¹ to 17.0 mL·min⁻¹·kg⁻¹ in women. Thus, the age- and sex-specific normal reference values of $\stackrel{·}{\mathrm{V}}$O_2peak were presented for each 10-year age group by men and women separately. Conclusions: This first community-based study in China provides age- and sex-specific normal references of $\stackrel{·}{\mathrm{V}}$O_2peak as a measure of CRF in Chinese adults, which differed significantly from those established in Western populations. Future studies with national representative samples should be warranted.

Clinical treatment strategies for musculoskeletal disorders have been a hot research topic. Accumulating evidence suggests that hydrogels loaded with MSC‐derived EVs show great potential in improving musculoskeletal injuries. The ideal hydrogels should be capable of promoting the development of new tissues and simulating the characteristics of target tissues, with the properties matching the cell‐matrix constituents of autologous tissues. Although there have been numerous reports of hydrogels loaded with MSC‐derived EVs for the repair of musculoskeletal injuries, such as intervertebral disc injury, tendinopathy, bone fractures, and cartilage injuries, there are still many hurdles to overcome before the clinical application of modified hydrogels. In this review, we focus on the advantages of the isolation technique of EVs in combination with different types of hydrogels. In this context, the efficacy of hydrogels loaded with MSC‐derived EVs in different musculoskeletal injuries is discussed in detail to provide a reference for the future application of hydrogels loaded with MSC‐derived EVs in the clinical treatment of musculoskeletal injuries.