Influences of remote exercise training for community-dwelling older adults in Japan during the COVID-19 pandemic.

[Purpose] The coronavirus disease (COVID-19) pandemic has caused sudden lifestyle changes. This study aimed to determine the limitations in activity and the influences of remote exercise training on community-dwelling older adults during a state of emergency in Japan. [Participants and Methods] In May 2020, during the COVID-19 state of emergency, we carried out a mail survey of community-dwelling older adults who had previously participated in a disability prevention program in Ami town, Ibaraki, Japan. The mail included a brochure on exercises and a DVD. The attached exercise program was comprised of 10 different exercises, which could be conducted in approximately 30 minutes. [Results] Of the 191 older adults, 73 responded to this survey (38.2%), of which 42 (58.5%) participants had decreased outdoor exercise activity, and 50 (68.5%) decreased the amount of time spent on physical activities during the COVID-19 state of emergency. There were significant reductions (19.2-22.5%) in the perceived exercise load for each posture after two weeks of remote exercise training with DVD (n=26). [Conclusion] Our results suggested that the remote exercise training with the brochure and DVD may be effective. Since this study involved a small number of participants, future studies should involve larger populations.

Association between Occupational Dysfunction and Social Isolation in Japanese Older Adults: A Cross-Sectional Study.

We clarified the relationship between occupational dysfunction and social isolation among community-dwelling adults. We used a self-administered questionnaire with a cross-sectional study for 2879 independently living older adults in Kasama City, Japan. Participants responded to a self-reported questionnaire in November 2019. Occupational dysfunction and social isolation were assessed. The participants were classified into two groups: healthy occupational function group, and occupational dysfunction group. To examine the relationship between occupational dysfunction and social isolation, we performed a logistic regression analysis with social isolation as a dependent variable and occupational dysfunction as an independent variable. In the crude model, the occupational dysfunction group had a higher risk of social isolation than the healthy occupational function group (odds ratio (OR) = 2.04; 95% confidence interval (CI), 1.63-2.55; p < 0.001). In the adjusted model, the occupational dysfunction group had a higher risk of social isolation than the healthy occupational function group (OR = 1.51; 95% CI, 1.17-1.94; p = 0.001). The results showed that occupational dysfunction was significantly associated with social isolation. These results can be used in constructing a support method for social isolation from a new perspective.

Skeletal Muscle Mass and Higher-Level Functional Capacity in Female Community-Dwelling Older Adults.

PURPOSE: In this study, our purpose was to examine the relationship between skeletal muscle mass and higher-level functional capacity in female community-dwelling older adults. Participant(s) and Methods: In this cross-sectional study, we targeted 55 female community-dwelling older adults aged 65 years and above participating in long-term care prevention classes in Ibaraki Prefecture between 2018 and 2020. We excluded individuals with cognitive impairment and those judged as having sarcopenia. The variables of interest included age, height, weight, body mass index, skeletal muscle mass index (SMI), handgrip strength, step count, and family structure. We calculated the SMI by dividing the extremities' total lean mass by the square of the height (in m), while the number of steps was calculated using the three-axis accelerometer Actigraph GT3X®. We measured skeletal muscle mass via bioelectrical impedance analysis using the InBody270 body composition analyzer and muscular strength as grip strength. RESULTS: We observed significant relationships between skeletal muscle mass and Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG-IC) (ß = 0.336, p < 0.01) and handgrip strength (ß = 0.230). CONCLUSION: In this study, a relationship between skeletal muscle mass and higher-level functional capacity was demonstrated among elderly female community residents.

Damage Evolution and Fracture Events Sequence Analysis of Core-Shell Nanoparticle Modified Bone Cements by Acoustic Emission Technique.

In this research, damage in bone cements that were prepared with core-shell nanoparticles was monitored during four-point bending tests through an analysis of acoustic emission (AE) signals. The core-shell structure consisted of poly(butyl acrylate) (PBA) as rubbery core and methyl methacrylate/styrene copolymer (P(MMA-co-St)) as a glassy shell. Furthermore, different core-shell ratios 20/80, 30/70, 40/60, and 50/50 were prepared and incorporated into the solid phase of the bone cement formulation at 5, 10, and 15 wt %, respectively. The incorporation of a rubbery phase into the bone cement formulation decreased the bending strength and bending modulus. The AE technique revealed that the nanoparticles play an important role on the fracture mechanism of the bone cement, since a higher amount of AE signals (higher amplitude and energy) were obtained from bone cements that were prepared with the nanoparticles in comparison with those without nanoparticles (the reference bone cement). The SEM examination of the fracture surfaces revealed that all of the bone cement formulations exhibited stress whitening, which arises from the development of crazes before the crack propagation. Finally, the use of the AE technique and the fracture surface analysis by SEM enabled insight into the fracture mechanisms that are presented during four-point bending test of the bone cement containing nanoparticles.

Evaluation of damage progression and mechanical behavior under compression of bone cements containing core-shell nanoparticles by using acoustic emission technique.

In this work, the effect of the incorporation of core-shell particles on the fracture mechanisms of the acrylic bone cements by using acoustic emission (AE) technique during the quasi-static compression mechanical test was investigated. Core-shell particles were composed of a poly(butyl acrylate) (PBA) rubbery core and a methyl methacrylate/styrene copolymer (P(MMA-co-St)) outer glassy shell. Nanoparticles were prepared with different core-shell ratio (20/80, 30/70, 40/60 and 50/50) and were incorporated into the solid phase of bone cement at several percentages (5, 10 and 15 wt%). It was observed that the particles exhibited a spherical morphology averaging ca. 125 nm in diameter, and the dynamic mechanical analysis (DMA) thermograms revealed the desired structuring pattern of phases associated with core-shell structures. A fracture mechanism was proposed taking into account the detected AE signals and the scanning electron microscopy (SEM) micrographs. In this regard, core-shell nanoparticles can act as both additional nucleation sites for microcracks (and crazes) and to hinder the microcrack propagation acting as a barrier to its growth; this behavior was presented by all formulations. Cement samples containing 15 wt% of core-shell nanoparticles, either 40/60 or 50/50, were fractured at 40% deformation. This fact seems related to the coalescence of microcracks after they surround the agglomerates of core-shell nanoparticles to continue growing up. This work also demonstrated the potential of the AE technique to be used as an accurate and reliable detection tool for quasi-static compression test in acrylic bone cements.

The effect of pressure during sintering on the strength and the fracture toughness of hydroxyapatite ceramics.

Hydroxyapatite (HA) is known to be biocompatible and osteoconductive, and can be synthesized chemically. The objective of the present study is to clarify the effect of pressure during sintering on the mechanical properties of HA. HA was sintered using a hot press system at a uniaxial pressure ranging from 7.81 to 62.5 MPa at a maximum temperature of 1200 degrees C with a heating rate of 10 degrees C/min. The density of the HA increased with increasing pressure and peaked at the sintering pressure of 31.2 MPa. Four-points bending tests and fracture toughness measurements with indentation method were conducted to clarify the effect of sintering pressure. Bending strength decreased at the pressure > 31.2 MPa. This result indicates that residual stress generated during sintering process became larger with increasing pressure. Fracture toughness were also lower with high density HA.