Yuya Watanabe

Echo intensity obtained from ultrasonography images reflecting muscle strength in elderly men

Background It is well known that loss of muscle mass (quantitative change) is a major change that occurs with aging. Qualitative changes in skeletal muscle, such as increased intramuscular fat, also occur as one ages. Enhanced echo intensity (EI) on ultrasonography images of skeletal muscle is believed to reflect muscle quality. Recent studies evaluating the quality of skeletal muscle using computer-aided gray scale analysis showed that EI is associated with muscle strength independently of age or muscle size in middle-aged and elderly women. The aim of the present study was to investigate whether muscle quality based on EI is associated with muscle strength independently of muscle size for elderly men. Methods A total of 184 elderly men (65–91 years) living independently in Kyoto, Japan, participated in this study. The EI, muscle thickness (MT), and subcutaneous fat thickness (FT) of the anterior compartment of the right thigh were determined by assessing ultrasonography images. The maximum isometric torque of knee extension at a knee angle of 90° was measured. Results The EI showed a significant negative correlation with muscle strength (r = −0.333, P < 0.001). Multivariate regression analysis revealed that the MT and EI of the knee extensor muscle were independently associated with maximum isometric knee extension strength. Even when partial correlation analysis was performed with age, height, weight, and FT as control variables, EI was still significantly correlated with muscle strength. Conclusion The results of this study indicate that aging-related changes in muscle quality contribute to diminishing muscle strength. Ultrasonography is a low-cost, easily accessible, and safe method suitable for the assessment of EI as an index of muscle quality.

Effect of very low-intensity resistance training with slow movement on muscle size and strength in healthy older adults

We previously reported that low‐intensity [50% of one repetition maximum (1RM)] resistance training with slow movement and tonic force generation (LST) causes muscle hypertrophy and strength gain in older participants. The aim of this study was to determine whether resistance training with slow movement and much more reduced intensity (30%1RM) increases muscle size and strength in older adults. Eighteen participants (60–77 years) were randomly assigned to two groups. One group performed very low‐intensity (30% 1RM) knee extension exercise with continuous muscle contraction (LST: 3‐s eccentric, 3‐s concentric, and 1‐s isometric actions with no rest between each repetition) twice a week for 12 weeks. The other group underwent intermitted muscle contraction (CON: 1‐s concentric and 1‐s eccentric actions with 1‐s rest between each repetition) for the same time period. The 1RM, isometric and isokinetic strengths, and cross‐sectional image of the mid‐thigh obtained by magnetic resonance imaging were examined before and after the intervention. LST significantly increased the cross‐sectional area of the quadriceps muscle (5·0%, P<0·001) and isometric and isokinetic knee extension strengths (P<0·05). CON failed to increase muscle size (1·1%, P = 0·12), but significantly improved its strength (P<0·05). These results indicate that even if the intensity is as low as 30% 1RM, LST can increase muscle size and strength in healthy older adults. The large total contraction time may be related to muscle hypertrophy and strength gain. LST would be useful for preventing sarcopenia in older individuals.

Comparison of single- or multifrequency bioelectrical impedance analysis and spectroscopy for assessment of appendicular skeletal muscle in the elderly

Bioelectrical impedance analysis (BIA) is used to assess skeletal muscle mass, although its application in the elderly has not been fully established. Several BIA modalities are available: single-frequency BIA (SFBIA), multifrequency BIA (MFBIA), and bioelectrical impedance spectroscopy (BIS). The aim of this study was to examine the difference between SFBIA, MFBIA, and BIS for assessment of appendicular skeletal muscle strength in the elderly. A total of 405 elderly (74.2 ± 5.0 yr) individuals were recruited. Grip strength and isometric knee extension strength were measured. Segmental SFBIA, MFBIA, and BIS were measured for the arms and upper legs. Bioelectrical impedance indexes were calculated by squared segment length divided by impedance (L2/Z). Impedance at 5 and 50 kHz (Z5 and Z50) was used for SFBIA. Impedance of the intracellular component was calculated from MFBIA (Z250-5) and BIS (RICW). Correlation coefficients between knee extension strength and L2/Z5, L2/Z50, L2/RICW, and L2/Z250-5 of the upper legs were 0.661, 0.705, 0.790, and 0.808, respectively (P < 0.001). Correlation coefficients were significantly greater for MFBIA and BIS than SFBIA. Receiver operating characteristic curves showed that L2/Z250-5 and L2/RICW had significantly larger areas under the curve for the diagnosis of muscle weakness compared with L2/Z5 and L2/Z50. Very similar results were observed for grip strength. Our findings suggest that MFBIA and BIS are better methods than SFBIA for assessing skeletal muscle strength in the elderly.

The Extracellular to Intracellular Water Ratio in Upper Legs is Negatively Associated With Skeletal Muscle Strength and Gait Speed in Older People.

Skeletal muscles contain a large volume of water that is classified into intracellular (ICW) and extracellular (ECW) water fractions. Nuclear magnetic resonance-based biomarkers suggest that increased water T2 heterogeneities, as well as elevated water T2 relaxation in the quadriceps occurs in the elderly when compared with young adults. However, nuclear magnetic resonance is difficult to apply to a large-scale study or a clinical setting for sarcopenia and frailty screening. Segmental bioelectrical impedance spectroscopy is a unique tool used to assess the segmental ratio of ECW/ICW in the limbs. We evaluated 405 community-living people aged between 65 and 90 years. ECW and ICW in the upper legs were assessed by segmental bioelectrical impedance spectroscopy. Isometric knee extension strength, gait speed, and skeletal muscle mass were measured. Thigh ECW/ICW was negatively correlated with knee extension strength and gait speed (r = -.617 and -.431, respectively, p < .001) and increased with age (p < .001). Thigh ECW/ICW was a significant predictor of knee extension strength and gait speed independent of age, sex, body mass index, and skeletal muscle mass. Relative expansion of ECW against ICW in the thigh muscles is a factor in decreased muscle quality and a biomarker of muscle aging.

Supplementation with eicosapentaenoic acid-rich fish oil improves exercise economy and reduces perceived exertion during submaximal steady-state exercise in normal healthy untrained men

Based on the effects of n-3 polyunsaturated fatty acids (PUFA) such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on reduction of blood viscosity, we theorized that PUFA could improve aerobic performance by increasing oxygen supply to tissues. Twenty male subjects were randomly divided into two groups (n = 10): a fish oil group (FG) and a control (CG). Maximal oxygen uptake and oxygen uptake during submaximal exercise were measured using a cycle ergometer. For 8 weeks, the FG then ingested capsules containing 3.6 g/day of EPA-rich fish oil, while the CG took 3.6 g/day of a medium-chain triglyceride. After supplementation, erythrocyte EPA and DHA in the FG were significantly increased. In the FG, a negative linear correlation was detected in the change between erythrocyte EPA and whole oxygen uptake during submaximal exercise pre- and post-supplementation. The present study showed that EPA-rich fish oil supplementation improves exercise economy in humans. Graphical Abstract Supplementation with fish oil for 8 weeks improved exercise economy and reduced perceived exertion during exercise in normal healthy untrained men.

Effect of resistance training using bodyweight in the elderly: Comparison of resistance exercise movement between slow and normal speed movement

The present study investigated whether a slow movement protocol can be applied to resistance training using bodyweight. In addition, the intervention program combined plyometric exercise with resistance exercise to improve physical function overall.

A novel class of bacterial translation factor RF3 mutations suggests specific structural domains for premature peptidyl-tRNA drop-off

The bacterial translation factor RF3 promotes translation termination by recycling the tRNA‐mimicking release factors, RF1 and RF2, after mature polypeptide release. RF3 also enhances the premature peptidyl‐tRNA drop‐off reaction in the presence of RRF and EF‐G. Despite the recently resolved X‐ray crystal structure of RF3, the molecular details of the bimodal functionality of RF3 remain obscure. In this report, we demonstrate a novel class of RF3 mutations specifically defective in the tRNA drop‐off reaction. These mutations suggest differential molecular pathways closely related to the guanine nucleotide modes of RF3.

Frequency of Fruit and Vegetable Consumption and the Oral Health-Related Quality of Life among Japanese Elderly: A Cross-Sectional Study from the Kyoto-Kameoka Study

Objective: Many previous studies have reported that fruit and vegetable consumption is associated with a reduced risk of various disease, but whether or not their consumption is associated with the oral health-related quality of life (OHRQoL) is unclear. The objective of this study was to examine the association between the frequency of fruit and vegetable consumption and the OHRQoL in elderly subjects by sex. Methods: We analyzed cross-sectional data from a population-based Kyoto-Kameoka Study in 2012 of 3112 men and 3439 women (age ≥ 65 years). The frequencies of fruit and vegetable consumption were assessed using a validated food frequency questionnaire. We evaluated the OHRQoL using the General Oral Health Assessment Index (GOHAI), a self-reported measure designed to assess the oral health problems in old adults. Results: After adjusting for age, body mass index, alcohol, smoking, education, socioeconomic status, history of disease, medication use, mobility disability, and total energy intake, a higher frequency of combined fruit and vegetable consumption showed a significant positive association with the GOHAI score in both men and women (p-trend < 0.001 in both sexes). These associations remained significant after adjustment for poor mastication and denture use (p-trend all < 0.05 in both sexes). We observed a significant positive association even when the frequencies of fruit or vegetable consumption were analyzed separately (all p-trend < 0.05 in both sexes). Conclusions: A higher frequency of fruit and/or vegetable consumption independently showed a strong positive association with the OHRQoL in both men and women. Further prospective studies are needed to confirm these findings.

[Fall risk factors and sex differences among community-dwelling elderly individuals in Japan. A Kameoka study].

OBJECTIVES Although factors associated with falls might differ between men and women, no large-scale studies were conducted to examine the sex difference of risk factors for falls in Japanese elderly. The purpose of this study was to examine fall risk factors and sex differences among community-dwelling elderly individuals using a complete survey of the geriatric population in Kameoka city. METHODS A self-administered questionnaire survey was conducted with 18,231 community-dwelling elderly individuals aged 65 years or over in Kameoka city, Kyoto Prefecture, between July and August 2011, excluding people who were publicly certified with a long-term care need of grade 3 or higher. The questionnaire was individually distributed and collected via mail. Out of 12,159 responders (recovery rate of 72.2%), we analyzed the data of 12,054 elderly individuals who were not certified as having long-term care needs. The questionnaire was composed of basic attributes, a simple screening test for fall risk, the Kihon Check List with 25 items, and the Tokyo Metropolitan Institute of Gerontology (TMIG) index of competence with 13 items. These items were grouped into nine factors: motor function, malnutrition, oral function, houseboundness, forgetfulness, depression, Instrumental Activity of Daily Living (IADL), intellectual activities, and social role. RESULTS Of all the respondents, 20.8% experienced falls within the last year, and 26.6% were classified as having high fall risk. Fall risk increased with age in both sexes, and risk in all age groups was higher for women than for men. All factors were significantly associated with fall risk in both sexes. After controlling for these factors, a significant relationship was found between fall risk and motor function, malnutrition, oral function, forgetfulness, depression, and IADL in men and motor function, oral function, forgetfulness, depression, and IADL in women. The deterioration of motor function was associated with three-times-higher risk than non-deterioration of motor function. In addition, significant interaction was found in sex×malnutrition, oral function, IADL, and intellectual activities; malnutrition and low oral function were stronger factors in men than in women; and IADL and intellectual activities were stronger factors in women than in men. CONCLUSION One in five community-dwelling independent elderly individuals experienced falls in the last year, and one in four had high fall risk. We found a significant relationship between fall risk and the nine factors, particularly deterioration of motor function in both sexes. Sex difference was observed for fall risk factors; therefore, a sex-specific support policy for fall prevention is necessary.

Association between the Frequency of Protein-Rich Food Intakes and Kihon-Checklist Frailty Indices in Older Japanese Adults: The Kyoto-Kameoka Study

We aimed to investigate whether frequencies of protein-rich food intake were associated with frailty among older Japanese adults. A cross-sectional study was conducted in 2011 among 3843 men and 4331 women in a population-based cohort of Kameoka city, Kyoto Prefecture, Japan. Frailty was assessed by the weighted score based on the 25-item Kihon-Checklist. The frequency of protein-rich food intake was examined as “seafood”, “meat”, “dairy products”, “eggs”, and “soy products”. The outcome of frailty was analyzed with a multiple logistic regression model using the frequency of protein-rich food intake. When compared to the first quartile, it was observed that there was a significant association between the lower adjusted prevalence ratio (PR) for frailty and the frequency of seafood intake in the fourth quartile among men (PR 0.64, 95% confidence interval (CI), 0.42, 0.99) and from the second quartile to the third quartile among women (PR 0.61, 95% CI, 0.43, 0.85; PR 0.64, 95% CI, 0.46, 0.91). The frequency of dairy products intake in the third quartile among women was significantly associated with a lower PR for frailty (p-value = 0.013). Our findings suggest that the consumption of seafood and dairy products may help older adults in maintaining their independence.