Association Between Relative Grip Strength, Insulin Resistance, and Nonalcoholic Fatty Liver Disease Among Middle-Aged and Older Adults: A Prospective Cohort Study

Introduction: This study aims to investigate the combined association between insulin resistance (IR) levels, relative grip strength (RGS), and the incidence of nonalcoholic fatty liver disease (NAFLD), stratified by sex, using longitudinal data. Methods: The study included 1702 adult participants aged 51-88 years who completed surveys in both 2013-2014 and during a subsequent follow-up in 2019-2020. NAFLD was assessed using the hepatic steatosis index, and RGS was measured using the JAMA-5030J1 equipment (SAEHAN, Korea). To assess the interaction between RGS and IR levels and their impact on NAFLD risk, we employed a proportional hazards Cox regression model. Hazard ratios (HR) and 95% confidence intervals (95% CI) were calculated for NAFLD incidence. Results: After adjusting for various confounding variables, we observed a significant decrease in NAFLD risk in the middle RGS group (HR = 0.70, 95% CI = 0.53-0.93) and high RGS group (HR = 0.31, 95% CI = 0.22-0.44) compared to the low RGS group. In addition, significant sex differences were noted in the relationship between IR, RGS levels, and NAFLD incidence across different groups. Conclusions: This study highlights that higher RGS levels are independently associated with a reduced risk of developing NAFLD. Notably, RGS emerges as a predictive indicator for assessing NAFLD risk.

Sex Differences in Effects of Exercise on Physical Function in Aging: A Systematic Review with Meta-Analysis

PURPOSE

Our objective was to synthesize and determine whether there are sex differences in physical function following exercise interventions in older adults.

MATERIALS AND METHODS

A systematic search was conducted in four databases from inception to July 8th, 2023 searching for prospective trials that conducted exercise interventions in older adults and results for physical function were reported by sex. Pooled standardized mean differences (SMDs) with their 95% confidence intervals (CIs) were estimated using a randomeffects method. The Sidik-Jonkman estimator was used to calculate the variance of heterogeneity (I²).

RESULTS

A total of 19 studies involving 20,133 older adults (mean age ≥60 years, 33.7% female) were included. After exercise interventions, males reported significantly greater pre-post changes compared to females for upper body strength (SMD=-0.40, 95% CI: -0.71 to -0.09; I²=75.6%; n=8), lower body strength (SMD=-0.32, 95% CI: -0.55 to -0.10; I²=52.0%; n=11), and cardiorespiratory fitness (SMD=-0.29, 95% CI: -0.48 to -0.10; I²=89.1%; n=12). Conversely, the pooled SMDs showed a significant effect favoring females for motor fitness (SMD=0.21, 95% CI: 0.03 to 0.39; I²=0%; n=7). Limited and inconsistent results were observed for flexibility.

CONCLUSIONS

Our study suggests the existence of sex-related differences on physical function after an exercise intervention in the older population.

Low Serum Total Carotenoids and β-Cryptoxanthin Are Associated with Low Lean Body Mass in Older Community-Dwellers in the National Institute for Longevity Sciences-Longitudinal Study of Aging: A 4-Y Longitudinal Study

BACKGROUND

Although diets rich in carotenoids are associated with muscle health and a reduced risk of disability, the relationship between carotenoids and low lean body mass has not been fully elucidated.

OBJECTIVES

This study aimed to clarify the relationship between serum carotenoid concentrations and low lean body mass over 4 y in older Japanese community-dwellers.

METHODS

A total of 750 adults aged ≥60 y participated in the National Institute for Longevity Sciences-Longitudinal Study of Aging. Individuals with a low lean body mass and muscle strength or gait speed at baseline were excluded. Baseline serum α-carotene, β-carotene, β-cryptoxanthin, zeaxanthin, lutein, and lycopene were measured. Low lean body mass was defined as appendicular lean mass relative to the measured height (ALM/ht2) of <7.0 kg/m2 in males and <5.4 kg/m2 in females, according to the criteria of the Asian Working Group for Sarcopenia 2019. A generalized estimating equation was used to estimate the odds ratio and 95% confidence interval for low lean body mass according to tertiles of total and individual carotenoids at baseline, adjusted for sex, age, season, follow-up months, education years, economic status, current smoking status, a history of ischemic heart disease, stroke, hypertension, dyslipidemia, diabetes mellitus, and metabolic equivalents.

RESULTS

Low serum total carotenoids were associated with low ALM/ht2, and the odds ratios of low ALM/ht2 in the third tertile of total carotenoids were significantly lower than those in the first tertile after adjusting for covariates. The odds ratios of low ALM/ht2 in the third tertile of β-cryptoxanthin were significantly associated with those in the first tertile after adjusting for covariates (P = 0.03); however, no trend was observed for this relationship.

CONCLUSIONS

These findings indicate that low serum total carotenoids and serum β-cryptoxanthin are associated with low lean body mass in older Japanese community-dwellers.

Optical Myography-Based Sensing Methodology of Application of Random Loads to Muscles during Hand-Gripping Training

Hand-gripping training is important for improving the fundamental functions of human physical activity. Bernstein's idea of "repetition without repetition" suggests that motor control function should be trained under changing states. The randomness level of load should be visualized for self-administered screening when repeating various training tasks under changing states. This study aims to develop a sensing methodology of random loads applied to both the agonist and antagonist skeletal muscles when performing physical tasks. We assumed that the time-variability and periodicity of the applied load appear in the time-series feature of muscle deformation data. In the experiment, 14 participants conducted the gripping tasks with a gripper, ball, balloon, Palm clenching, and paper. Crumpling pieces of paper (paper exercise) involves randomness because the resistance force of the paper changes depending on the shape and layers of the paper. Optical myography during gripping tasks was measured, and time-series features were analyzed. As a result, our system could detect the random movement of muscles during training.

Implication of grip strength assessment for the management of body weight in disability prevention in older adults

BACKGROUND

Although body mass index (BMI) and grip strength (GS) are both predictors of disability, their joint effect on predicting incident disability remains uncertain. We examined whether the effect of BMI on incident disability can be modulated by GS in community-dwelling older people in Japan.

METHODS

A total of 1486 community-dwellers in Japan (731 men and 755 women, aged 65-82 years) who participated in the 2nd to 7th waves of the National Institute for Longevity Sciences-Longitudinal Study of Aging (NILS-LSA) project, were followed up to 20 years. Twelve subgroups were created according to the intersections of GS (sex-specific tertiles: low, intermediate, and high) and BMI (underweight 1, <18.5; underweight 2, 18.5-<21.5; normal, 21.5-<25.0; and overweight/obese, ≥25.0 kg/m2 ). Incident disability was defined as requiring care need level 1 or higher, as per the long-term care insurance system in Japan. The hazard ratios (HR) and corresponding 95% confidence intervals (CI) of incident disability (the 'high GS-normal BMI' subgroup was used as the reference) were calculated using a multivariable-adjusted Cox proportional hazards model. The model was adjusted for baseline characteristics on sex, participation wave, smoking, depressive symptoms, total physical activity, disease history, education level, residential status, and energy intake.

RESULTS

Compared with that for participants in the 'high GS-normal BMI' group, the risk of incident disability was higher for participants in the 'low GS-normal BMI', 'low GS-overweight/obese', 'intermediate GS-underweight 1' and 'intermediate GS-overweight/obese' groups. The multivariable-adjusted HR (95% CI) were 1.72 (1.27-2.32, P value<0.001), 1.81 (1.27-2.58, P value = 0.001), 2.42 (1.35-4.32, P value = 0.003) and 1.53 (1.06-2.20, P value = 0.023), respectively. The results did not change substantially when participants with disability occurring within 1 and 2 years of follow-up were excluded, or when the competing events were death without incident disability or dementia.

CONCLUSIONS

The joint effect of BMI and GS was more pronounced in those of normal weight or overweight/obese status and low GS, along with underweight or overweight/obese status and intermediate GS in predicting disability. The lack of observed joint effect for those underweight with low GS was likely due to insufficient sample size. GS consideration is necessary for weight management in older adults, and interventions for individuals who are underweight or overweight/obese with adequate GS need not be prioritized for disability prevention.

The Relationship between Restrictions on Going Out and Motor Imagery among Medical University Students in Japan—Research with Small Samples

Motor imagery is often used as a training method to improve physical performance. Previous studies have often reported that reduced motor imagery is more likely to occur in older adults and stroke patients. However, it has also been reported that it is difficult to imagine exercises that cannot be performed. Therefore, we hypothesized that this may also have occurred in young people who were physically able to exercise but who were restricted by COVID-19 lockdowns, however, we could find no studies that investigated the impact of restricting outings. In this study, 83 healthy young people were measured for physical performance (maximum walking speed, grasp strength, Timed Up and Go test, imagined Timed Up and Go test, functional reach test, and five chair stand test). It was found that, while restricting outings did not influence physical performance in the subjects, it did influence motor imagery. Therefore, it should be borne in mind that training with motor imagery may not generate adequate actual motor imagery when restrictions are imposed on activities.

Difference of the association between low muscle mass and physical inactivity by sex resulting from the choice of the diagnostic criterion for low muscle mass in elderly Koreans

AIM

We investigated the difference in the relationship between physical activity and low muscle mass resulting from the choice of diagnostic criterion for low muscle mass.

METHODS

Our study was cross-sectional, using data from the 2008-2011 National Health and Nutrition Examination Survey. Muscle mass was measured by dual-energy X-ray absorptiometry. Low muscle mass was defined as height-adjusted and weight-adjusted low muscle mass. Odds ratios (ORs) and 95% confidence intervals (CIs) of low muscle mass in relation to physical inactivity were analyzed using multivariate logistic regression analysis.

RESULTS

Our study included 3977 older people (1698 men and 2279 women). The prevalence of height-adjusted and weight-adjusted low muscle mass was 4.1% and 11.8%, respectively, in the physically inactive group, and 3.9% and 7.9%, respectively, in the physically active group. The prevalence of weight-adjusted low muscle mass increased by 48% in the physically inactive group in the fully adjusted model (OR, 1.48; 95% CI, 1.13-1.95) and increased by 61% in men and 50% in women (men: OR, 1.61; 95% CI, 1.12-2.31 and women: OR, 1.50; 95% CI, 1.20-2.20) compared with the physically active group. The risk of height-adjusted low muscle mass in men tended to be higher in the physically inactive group than in the physically active group. However, this trend was not observed among women.

CONCLUSIONS

Physical inactivity was associated with an increased prevalence of low muscle mass in weight-adjusted measures among elderly adults in Korea. Height-adjusted low muscle mass in women is less useful as an indicator of the relationship between low muscle mass and physical inactivity. Geriatr Gerontol Int 2023; 23: 71-77.

Prediabetes is an independent risk factor for sarcopenia in older men, but not in older women: the Bunkyo Health Study

BACKGROUND

Sarcopenia is a major cause of disability in the elderly. Although type 2 diabetes is a risk factor for increased sarcopenia, the relationship between prediabetes and sarcopenia has not been elucidated. We aimed to examine the relationship between sarcopenia and prediabetes.

METHODS

The design of this study is a cross-sectional study. We evaluated glucose metabolism using the 75-g oral glucose tolerance test and glycated haemoglobin, appendicular skeletal muscle mass, and hand grip strength in 1629 older adults living in an urban area of Tokyo, Japan. We investigated the frequency of sarcopenia in participants with normal glucose tolerance (NGT), prediabetes and diabetes. A multivariable logistic regression model was used to analyse the association between glucose tolerance and the prevalence of sarcopenia.

RESULTS

The mean age of participants was 73.1 ± 5.4 years. In men, 44.3% had NGT, 26.6% had prediabetes, and 29.1% had diabetes. In women, the distribution was 56.1%, 28.8% and 15.2%. The prevalence of sarcopenia was 12.7% in men and 11.9% in women. Logistic regression revealed that prediabetes and diabetes are independent risk factors for sarcopenia in men (prediabetes, odds ratio [OR] = 2.081 [95% confidence interval {CI}: 1.031-4.199]; diabetes, OR = 2.614 [95% CI: 1.362-5.018]) and diabetes, but not prediabetes, is an independent risk factor for sarcopenia in women (prediabetes, OR = 1.036 [95% CI: 0.611-1.757]; diabetes, OR = 2.099 [95% CI: 1.146-3.844]). In both sexes, higher age (men, OR = 1.086 [95% CI: 1.028-1.146]; women, OR = 1.195 [95% CI: 1.142-1.251]), higher body fat percentage (men, OR = 1.346 [95% CI: 1.240-1.461]; women, OR = 1.218 [95% CI: 1.138-1.303]) and lower body mass index (men, OR = 0.371 [95% CI: 0.299-0.461]; women, OR = 0.498 [95% CI: 0.419-0.593]) were independent risk factors for sarcopenia.

CONCLUSIONS

Although we confirmed that diabetes mellitus is associated with sarcopenia in both sexes, prediabetes is associated with sarcopenia in men, but not in women.

Association of renal function with muscle strength in Korean adults: A population-based study using the Korea National Health and Nutrition Examination Surveys (KNHANES) from 2014 to 2018

Hand grip strength (HGS), a simple measure of upper limb muscle function, can be used to assess overall muscular strength, and reduced HGS in patients with poor renal functions has been observed. This study examined the associations between renal function and HGS, a surrogate marker of muscular strength, among a stratified sample of Korean adults. This study obtained data from the Korea National Health and Nutrition Examination Survey from 2014 to 2018, a cross-sectional and nationally representative survey conducted by the Korea Centers for Diseases Control and Prevention. In men, low muscle strength (LMS) and normal muscle strength (NMS) were defined as HGS < 28.9 kg and HGS ≥ 28.9 kg, respectively. In women, LMS and NMS were considered as HGS < 16.8 kg and HGS ≥ 16.8 kg, respectively. Of the 25,746 subjects in this study, there were 3603 (14.0%) and 22,143 (86.0%) subjects who displayed LMS and NMS, respectively. Subjects with estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 had a higher risk of developing LMS than those with eGFR ≥ 60 mL/min/1.73 m2 after adjusting for age (odds ratio, 1.772; 95% CI, 1.498-2.096); the significant differences remained after adjusting for other factors including age. Similar tendencies were shown in men and women when analyzed according to gender; however, the risk of developing LMS was higher in men than in women. Results showed that decreased renal function was likely to contribute to an increased prevalence of LMS based on HGS. This association may assist in developing better strategies to estimate renal function in clinical or public health practice.

Hospitalization is associated with handgrip strength decline in older adults: a longitudinal study

BACKGROUND

Hospitalization episodes in older people are considered critical events because they act in a complex interaction among immobilization effects.

AIM

The purpose of this study was to evaluate the effects of hospitalization on older adults' handgrip strength (HGS) and to identify factors related to its performance on the test.

METHODS

A cohort study was conducted in a hospital in Natal, Brazil, and enrolled all patients aged 60 years and older between January 2014, and April 2015. Cognitive (Leganés Cognitive Test) and functional status (Katz Index, Lawton Scale and Functional limitation Nagi), physical performance (HGS and gait speed) and depressive symptom assessment (GDS-15) were evaluated at admission and discharge time, as well as information about health and functional status prior to hospitalization. Linear Mixed Models were used to create a predictive model for handgrip strength.

RESULTS

A total of 1168 hospitalized older adults were evaluated. A significant decrease in HGS means was observed between admission and discharge time for men (28.12 ± 10.35 and 20.22 ± 14.08 Kgf, p < 0.01) and for women (19.18 ± 7.87 and 14.88 ± 9.79 Kgf, p < 0.01). Undergoing surgery and basal values of the Katz Index were associated with worse HGS performance at discharge.

CONCLUSION

A significant decline in handgrip strength during the hospitalization period was observed, which was more pronounced in men. Performing surgery during hospitalization was an important factor for HGS decline in men and women. This study reinforces the importance of early mobilization and muscle strength loss prevention protocols in hospitalized older patients.

Accuracy of exercise-based tests for estimating cardiorespiratory fitness and muscle strength in early-stage breast cancer survivors in Japan

PURPOSE

We aimed to examine whether cardiorespiratory fitness and leg strength can be estimated based on their relationship with physical performance tests in Japanese breast cancer survivors.

METHODS

Participants were 50 sedentary women aged 20 to 59 years who have received breast surgery in the past 2 to 13 months after diagnosis of invasive breast cancer (stage I-IIa). Cardiorespiratory fitness and leg strength were measured by peak oxygen consumption (VO₂peak), and one-repetition maximum for leg press (leg press 1RM). Physical performance tests were performed 6-min walk test, chair stand test, and grip strength. Using multiple regression analysis, we developed prediction equations for VO₂peak and leg strength based on their associations with the physical performance tests. The validity of the estimation equations was assessed using Bland-Altman plots.

RESULTS

Mean age, VO₂peak, and leg press 1RM were 48 ± 6 years, 25.0 ± 3.6 mL/kg/min, and 95 ± 32 kg, respectively. Multiple regression analysis yielded 6-min walk test distance, age, height, and body weight as predictors of VO₂peak. Measured VO₂peak and predicted VO₂peak showed a moderate positive correlation (r = 0.463, p < 0.001). Chair stand test, grip strength, age, height, and body weight were selected as predictors of leg press 1RM. There was a strong positive correlation between predicted and measured leg press 1RM (r = 0.754, p < 0.001).

CONCLUSION

The results suggest that leg strength can be predicted using physical performance tests. However, further examination may be needed to determine whether cardiorespiratory fitness can be predicted based on 6-min walk test.

Minimal detectable change in handgrip strength and usual and maximum gait speed scores in community-dwelling Japanese older adults requiring long-term care/support

Aging is an important issue in Japan that has led to a large number of older adults requiring long-term care/support. Therefore, we determined the range of measurement error in the measurement of handgrip strength and gait speed which are representative tests. This cross-sectional study included 111 community-dwelling Japanese older adults aged ≥65 years who required long-term care/support and underwent ambulatory rehabilitation. Handgrip strength and usual and maximum gait speed were measured on two days in one single week. Minimal detectable change (MDC) was calculated. The MDC in handgrip strength was 2.9 kg for the overall population, 3.2 kg for the male participants, and 2.4 kg for the female participants. For the overall population, the MDC in usual gait speed was 0.18 m/s and that in maximum gait speed was 0.23 m/s. These MDCs are expected to be suitable for judging clinical changes because this study considered gender and typical tests.

Sex Differences in Adaptations in Muscle Strength and Size Following Resistance Training in Older Adults: A Systematic Review and Meta-analysis

BACKGROUND

Reductions in muscle size and strength occur with aging. These changes can be mitigated by participation in resistance training. At present, it is unknown if sex contributes to differences in adaptation to resistance training in older adults.

OBJECTIVE

The aim of this systematic review was to determine if sex differences are apparent in adaptations to resistance training in older adults.

DESIGN

Systematic review with meta-analysis.

DATA SOURCES

Web of Science; Science Direct; SPORTDiscus; CINAHL; and MEDLINE were searched from inception to June 2020.

ELIGIBILITY CRITERIA

Studies where males and females older than 50 years of age performed identical resistance training interventions and had outcome measures of muscle strength or size.

RESULTS

We initially screened 5337 studies. 30 studies (with 41 comparison groups) were included in our review (1410 participants; 651 males, 759 females). Mean study quality was 14.7/29 on a modified Downs and Black checklist, considered moderate quality. Females gained more relative lower-body strength than males (g = - 0.21 [95% CI - 0.33, - 0.10], p = 0.0003) but there were no differences in relative change for upper-body strength (g = - 0.29 [95% CI - 0.62, 0.04], p = 0.08) or relative muscle size (g = 0.10 [95% CI - 0.04, 0.23], p = 0.16). Males gained more absolute upper-body strength (g = 0.48 [95% CI 0.09, 0.88], p = 0.016), absolute lower-body strength (g = 0.33 [95% CI 0.19, 0.47], p < 0.0001), and absolute muscle size (g = 0.45 [95% CI 0.23, 0.66], p < 0.0001).

CONCLUSION

Our results indicate that sex differences in adaptations to resistance training are apparent in older adults. However, it is evident that the interpretation of sex-dependent adaptations to resistance training is heavily influenced by the presentation of the results in either an absolute or relative context.

STUDY REGISTRATION

Open Science Framework (osf.io/afn3y/).

Age-Related Changes in Physical Fitness Among Community-Living Middle-Aged and Older Japanese: A 12-Year Longitudinal Study

Physical fitness is one of the key factors in healthy aging. Although physical fitness is widely recognized to decline with age, age-related decreases in the individual dimensions of physical fitness in later life are less clear. Purpose: The purpose of the present study was to describe the age-related changes in six fitness components covering a variety of motor dimensions in men and women through a 12-year longitudinal epidemiological study. Method: Participants were randomly selected community-living men (n = 1,139) and women (n = 1,128) aged 40 to 79 years at baseline who were repeatedly tested over a mean (standard deviation) follow-up period of 9.8 (3.4) years with a mean of 4.9 (2.3) examinations. The six physical fitness tests were sit-and-reach, grip strength, sit-ups, one-leg standing, reaction time and leg extension power. The effect of age on each physical fitness task was analyzed using a mixed-effects model controlling for habitual physical activity level. Results: The fixed effect of the interaction of age and time in all fitness tests was significant in men. Higher age at baseline was significantly associated with a greater decrease over time except in one-leg standing. In women, no significant interaction effect of age and time was found in grip strength or reaction time. Age-related changes in grip strength and reaction time were constant with increasing age. Conclusion: Twelve-year longitudinal data showed that the age-related decrease in physical fitness over time, especially musculoskeletal fitness in men, was pronounced, whereas in women, the decrease was less pronounced.

Association between Physical Activity Levels and Body Composition among Healthy Older Japanese Adults during a Snowy Winter: A Cross-Sectional Study

BACKGROUND

Despite a long average lifespan, increased life expectancy does not guarantee higher quality of life.

METHODS

To contribute in understanding some determinants of healthy life expectancies in older Japanese individuals in a snowy winter region, we investigated the indicators of health. Local residents (n = 124) in the city of Iwamizawa volunteered for health examinations from January 2016 to March 2016. We recorded activity via daily steps for 2-week periods. In addition, we measured body composition, grip strength, and assessed nutritional status.

RESULTS

Analysis of body composition and daily activity indicated that women who walked more than 4000 steps had lower fat mass and increased muscle mass. Men with >3.0 metabolic equivalents (METs) when walking had lower body fat.

CONCLUSION

For healthy older Japanese individuals in this snowy winter region, walking >4000 steps daily for women and exercise of >3.0 METs for men may indicate health-promoting activities.

Role of gait speed and grip strength in predicting 10-year cognitive decline among community-dwelling older people

BACKGROUND

The gait speed and handgrip strength represented the core determinants of physical frailty and sarcopenia, which were reported to be associated with cognitive impairment and decline. Different physical measures might differentially affect cognitive changes, such as higher-level cognitive change and global cognitive decline. This study examined the differential associations of gait speed and handgrip strength with 10-year cognitive changes among community-dwelling older people.

METHODS

Participants aged 60 years and over living in the community were invited for study. Gait speed and handgrip strength were classified into 5 groups based on quintiles at baseline. Cognitive functions were assessed using the Mini-Mental State Examination (MMSE) and Digit Symbol Substitution Test (DSST) every 2 years from baseline for a period of 10 years. Linear mixed effects models were used to determine the role of gait speed and handgrip strength in the prediction of 10-year cognitive changes by adjusting covariates, including age, gender, education, depressive symptoms, marital status, smoking status, instrumental activities of daily life (IADL), Charlson Comorbidity Index (CCI), and body mass index (BMI) at baseline.

RESULTS

A total of 1096 participants were enrolled in the study. The mean age was 69.4 ± 5.8 years and 50.9% were male. The slowest gait speed group showed a significantly greater decline in the DSST scores over 10 years than the highest group (estimate = 0.28 and P = 0.003), but not in the MMSE scores (estimate = 0.05 and P = 0.078). The lowest handgrip strength group showed a significantly greater decline in the MMSE scores than the highest group (estimate = 0.06 and P = 0.039) and in the DSST scores than the highest two quintiles (estimate = 0.20 and P = 0.033 for the fourth quintile; estimate = 0.20 and P = 0.040 for the highest quintile) over 10-year follow-up.

CONCLUSIONS

A slow gait speed could predict 10-year cognitive decline using DSST, and a low handgrip strength could predict 10-year cognitive decline using MMSE in addition to DSST. Thus both physical measures are lined to cognitive decline but there may be different mechanisms between brain and physical functions.