Deteriorating sleep quality and physical or mental fatigue in older adults leads to decreased quality of life and increased mortality rates. This study investigated the effects of the time-dependent intake of nicotinamide mononucleotide (NMN) on sleep quality, fatigue, and physical performance in older adults. This randomized, double-blind placebo-controlled study evaluated 108 participants divided into four groups (NMN_AM; antemeridian, NMN_PM; post meridian, Placebo_AM, Placebo_PM). NMN (250 mg) or placebo was administered once a day for 12 weeks. Sleep quality was evaluated using the Pittsburgh Sleep Quality Index. Fatigue was evaluated using the “Jikaku-sho shirabe” questionnaire. Grip strength, 5-times sit-to-stand (5-STS), timed up and go, and 5-m habitual walk were evaluated to assess the physical performance. Significant interactions were observed between 5-STS and drowsiness. 5-STS of all groups on post-intervention and drowsiness of the NMN_PM and Placebo_PM groups on mid- and post-intervention showed significant improvement compared with those in pre-intervention. The NMN_PM group demonstrated the largest effect size for 5-STS (d = 0.72) and drowsiness (d = 0.64). Overall, NMN intake in the afternoon effectively improved lower limb function and reduced drowsiness in older adults. These findings suggest the potential of NMN in preventing loss of physical performance and improving fatigue in older adults.

This study aimed to investigate the association of sarcopenia and type 2 diabetes (T2D) with blood parameters, nutrient intake, and physical activity in older Korean adults. We divided 2952 participants into four groups: sarcopenic diabetes (SD), sarcopenia alone (S), diabetes alone (D), and non-sarcopenia and non-diabetes (NSND). Sarcopenia was defined by the appendicular skeletal muscle mass index, and T2D by fasting glucose levels or ongoing treatment. Blood samples were collected after an 8-h fast. Nutrient intake was assessed using a 24-h recall; physical activity was evaluated using a questionnaire. Compared with those in the other groups, the men in the S and SD groups showed significantly lower hemoglobin and hematocrit levels; vitamin D levels in men and parathyroid hormone levels in women were significantly lower in the SD group. Total energy, protein, and carbohydrate intakes were significantly lower in the SD and S groups than those in the D and NSND groups. Physical inactivity was significantly more common in the SD group (men: odds ratio, 1.61; women: odds ratio, 2.37) than in the NSND group. A combination of sarcopenia and diabetes as well as sarcopenia alone was associated with low levels of blood parameters, poor nutrient intake, and low physical activity.

The combined intake of citrulline (CIT) and leucine (LEU) can stimulate protein synthesis. Therefore, this study aimed to investigate the effect of combined intake of CIT and LEU accompanied by exercise for 20 weeks on body composition, physical activity (PA), and amino acid concentrations in older Japanese women with low body mass index (BMI) (16 to 21 kg/m²) using a randomized, double-blind, placebo-controlled design. The supplement was administered twice a day for 20 weeks (Ex (exercise) + CIT·LEU group, n = 10: mainly 0.8 g CIT and 1.6 g LEU; Ex + Placebo group, n = 13: mainly 3.5 g carbohydrate). Additionally, both groups exercised (weight-bearing exercise, square stepping exercise) once a week for 75 min. Body composition, PA, and amino acid concentrations in the plasma were measured. Body weight, BMI, body mass, household PA, total PA, and phenylalanine significantly increased in the Ex + CIT·LEU group (p < 0.05) post intervention. This study suggests that the combined intake of CIT and LEU accompanied by exercise can improve body weight, BMI, body mass, and PA in older women with low BMI, which may prevent sarcopenia and frailty.

This study examined the associations between dynapenia, metabolic syndrome (MetS), nutrient intake, and physical activity. We used data from a cross-sectional study that included middle-aged men and women (40–64 years old) who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) between 2014 and 2017. Patients (n = 4700) were categorized into four groups based on diagnosis of dynapenia and MetS: dynapenic MetS (DM), dynapenia alone (D), MetS alone (M), and non-dynapenia and non-MetS (NDNM). Dynapenia was defined as the lowest tertile of the BMI-adjusted handgrip strength. MetS was defined as central obesity plus two or more of the following features: elevated fasting plasma glucose, blood pressure, or triglycerides, or reduced HDL cholesterol. Nutrient intake and physical activity were assessed via questionnaires. In women, the DM group had a significantly lower intake of all nutrients except for total energy and carbohydrates compared to the NDNM group. In a model adjusted for age, osteoarthritis, and total energy intake, the DM group showed higher odds ratios (ORs) for not practicing resistance training (men: OR (95% confidence intervals (CI)) = 1.64 (1.22–2.20); women: OR (95% CI) = 2.26 (1.59–3.21)) and for engaging in physical activities below 600 metabolic equivalents of tasks per week (men: OR (95% CI) = 1.36 (1.05–1.78); women: OR (95% CI) = 1.29 (1.02–1.63)) than the NDNM group. The women in the DM group had significantly higher OR for leisure-related moderate (OR (95% CI) = 2.00 (1.49–2.68)) and vigorous (OR (95% CI) = 1.76 (1.10–2.82)) physical inactivity than in the NDNM group. This study showed that the combination of dynapenia and MetS was associated with poor nutrient intake in women and low physical activity in both sexes. These findings provide a foundation for developing intervention strategies to address dynapenia and MetS.

Because obesity is associated with impaired glucose tolerance and type 2 diabetes (T2D), it is important to manage the blood glucose level at an early stage. Nevertheless, people with obesity have significantly lower resistance to muscle fatigue after exercise and exercise adherence. Therefore, we developed a novel “Relaxing-Vibration Training (_RVT)” consisting of 25 postures using vibration stimulation of skeletal muscle and determined the feasibility of _RVT for glycemic management. Thirty-one participants with obesity were enrolled in a controlled trial (CT) and experimental trial (ET) based on a 75 g oral glucose tolerance test (OGTT). During the CT, participants were required to rest in a quiet room. During the ET, the _RVT program (50 Hz, 4 mm), consisting of 25 postures of relaxation and stretching on the vibratory platform, was performed for 40 min. Subsequently, the participants rested as in the CT. Subjective fatigue and muscle stiffness measurements and blood collection were conducted before and after _RVT. In both the CT and ET, interstitial fluid (ISF) glucose concentrations were measured every 15 min for 2 h. The incremental area under the curve value of real-time ISF glucose during an OGTT was significantly lower in the ET than in the CT (ET: 7476.5 ± 2974.9, CT: 8078.5 ± 3077.7, effect size r = 0.4). Additionally, the levels of metabolic glucose regulators associated with myokines, muscle stiffness, and subjective fatigue significantly improved after _RVT. This novel _RVT suggests that it is effective in glycemic management with great potential to improve impaired glucose tolerance and T2D with obesity in the future.