Aim:We examined the association of muscle mass and muscle strength with insulin resistance, focusing on lower limb muscles.Methods: This was a cross-sectional study, and participants were registered in 2017 from the Tanno-Sobetsu Study, a population-based cohort study. After excluding individuals aged <64 years or with a history of diabetes mellitus, 272 non-diabetic older adults (116 men, 156 women) met the inclusion criteria. According to the homeostasis model assessment of insulin resistance, the participants were divided into two groups; that is, the insulin resistance group (homeostasis model assessment of insulin resistance ≥1.73) and non-insulin resistance group (homeostasis model assessment of insulin resistance <1.73). Muscle mass (lower limb, upper limb, appendicular and trunk) and muscle strength (grip strength and knee extension torque) were measured and divided by the weight, and then multiplied by 100 to calculate the weight ratio (%). The adjusted odds ratio (OR) of each muscle index for risk of insulin resistance was calculated separately for both men and women.Results: Lower limb muscle mass (OR 0.72, 95% CI 0.55-0.92 in men; OR 0.69, 95% CI 0.51-0.96 in women, respectively) and appendicular muscle mass (OR 0.75, 95% CI 0.61-0.94 in men; OR 0.72, 95% CI 0.54-0.95 in women, respectively), but not other muscle indexes, were associated with risk of insulin resistance, after adjusting for age, body mass index, highly sensitive C-reacting protein and smoking habits.Conclusions: Lower limb muscle mass of non-diabetic older adults is independently related to insulin resistance.

[Purpose] The purpose of this study was to examine the reliability and validity of measurements of hip extensor muscle strength using a handheld dynamometer (HHD) with subjects in a sitting position. In doing so, we also aimed to establish a modified method of measurement for patients with flexion contractures in the trunk and lower extremities. [Subjects and Methods] In 20 healthy males, hip extensor muscle strength was measured using a handheld dynamometer in sitting, prone, and standing positions by contracting the hip extensor muscle isometrically with the knee flexed at 90 degrees. For each position, we investigated the relative and absolute reliability and validity of the measurements, and compared muscle strength between the different positions. [Results] The reliability and validity of measurements were highest in the sitting position and higher in both the sitting and standing positions as compared with those in the prone position. [Conclusion] Our findings suggest that measurements taken in a sitting position are accurate in assessing hip extensor muscle strength and would be applicable to patients with flexion contractures in the trunk and lower extremities.

[Purpose] This study aimed to examine the influence of climatic conditions on the daily physical activities of elderly individuals by comparing the physical activity during seasons with and without snowfall. [Participants and Methods] In total, 35 participants attending the Health Promotion Program conducted by Chitose City Office participated in this study. The survey for the seasons with snowfall was conducted in February 2016, while the survey for the seasons without snowfall was conducted in September 2015. The physical activity of the participants was measured using a Kenz Lifecorder GS accelerometer. [Results] Physical activity was found to be significantly lower during seasons with snowfall than in seasons without snowfall. Multivariate analysis revealed that physical activity significantly increased with lower temperature during the seasons with snowfall, and it significantly increased with higher temperature and decreased with larger amounts of precipitation during the seasons without snowfall. [Conclusion] It was found that the climatic conditions affect the level of physical activity during seasons with and without snowfall. A lower level of physical activity was observed in areas that received snowfall than in areas that did not receive snowfall.

The effects of different postures on the static flexion relaxation phenomenon were compared using electromyography, to clarify whether the angles for the activation and relaxation of the spinal muscles are different. [Subjects and Methods] Thirty healthy males maintained several different trunk inclination angles while standing and sitting. The muscle activities were measured and compared among the different postures and the different trunk angles: 0, 10, 20, 30, 40, 50, 60, and maximum forward leaning. The thoracic and lumbar erector spinae, multifidus, gluteus maximus, and biceps femoris were the target muscles. [Results] Muscle activities increased with increasing forward inclination angle, but at low inclination angles in the sitting position, the activities of the multifidus and erector spinae were constant. Between the postures, trunk muscle activities became significantly lower in the sitting position than in the standing position with increasing inclination. [Conclusion] Compared to standing, muscle activities at low inclination angles have low, constant values.