OBJECTIVES: This study investigated whether the lower extremity muscle mass index (LMI) mediates the relationship between general obesity, central obesity, and knee osteoarthritis in middle-aged and elderly women in Korea.METHODS: Data of 2,843 women aged ≥50 years were collected from the Korean National Health and Nutrition Examination Survey conducted between 2009 and 2011. General obesity and central obesity were evaluated based on body mass index (BMI) and waist circumference (WC), calculated through anthropometric measurements and body composition assessments. LMI was calculated by dividing the muscle mass in both legs—measured using the dual-energy X-ray absorptiometry—by body weight. Knee osteoarthritis was defined as a Kellgren-Lawrence scale (KL) grade of ≥2 as assessed through radiographic images.RESULTS: Knee osteoarthritis prevalence, indicated by KL grades, was significantly higher in the general obesity and central obesity groups compared to the normal group, and conversely, lower with varying LMI levels. Using mediation analysis with bootstrapping and adjusting for covariates, we found that LMI mediated the relationship between BMI and KL (β, 0.005; 95% confidence interval [CI], 0.000 to 0.010) and WC and KL grade (β, 0.002; 95% CI, 0.001 to 0.003), explaining 4.8% and 6.7% of the total effects of BMI and WC on KL grade, respectively.CONCLUSIONS: The study suggested that LMI partially mediates the link between general obesity and/or central obesity and knee osteoarthritis, proposing that a higher proportion of lower limb muscle mass relative to body weight can alleviate the increased risk of knee osteoarthritis caused by obesity.

PURPOSE: This study aimed to determine the cutoff values for gait and health-related physical fitness associated with osteoporosis in community-dwelling elderly women.METHODS: A total of 180 elderly women (aged ≥60) participated. Stepwise multiple regression was used to identify the predictors of femoral neck-bone mineral density (FN-BMD) from the gait and fitness variables. A receiver operating characteristic (ROC) analysis was used to determine the cutoff points and predict the performance of osteoporosis. Finally, logistic regression was used to calculate the odds ratio (OR) and 95% confidence interval (CI) of osteoporosis risk.RESULTS: Fast-pace stride length and upper body strength were identified as independent predictors of FN-BMD. The cutoff values for predicting osteoporosis were 129.2 cm (accuracy, 70.6%) for fast-pace stride length and 18.0 kg (accuracy, 69.4%) for upper body strength. Logistic regression analysis showed that the below-threshold group had a significantly higher risk (fast pace stride length: OR=6.063, 95% CI=2.195-16.753, p<.001; upper body strength: OR=5.079, 95% CI=1.798-14.346, p=.002) of osteoporosis than the above-threshold group, and this result remained significant even after adjusting for covariates.CONCLUSIONS: The findings of this study suggest that measuring fast-pace stride length and grip strength, which can be easily assessed, may serve as useful tools for identifying osteoporosis risk in elderly women.

To examine the association between body fat distribution, dysmobility syndrome, and cognitive impairment in 181 community-dwelling older women and assess physical activity's mediating role. Body composition was assessed using dual-energy X-ray absorptiometry, and the android-to-gynoid (A/G) fat ratio was calculated as the android fat proportion divided by the gynoid fat proportion. Participants were categorized into high and low 50 % groups based on the A/G fat ratio. Dysmobility syndrome was defined as the presence of at least three of the following: increased body fat percentage, decreased muscle mass, osteoporosis, slow gait speed, reduced grip strength, or a history of falls. Cognitive impairment was defined as a Mini-Mental State Examination for Dementia Screening score ≤ 23. Physical activity was measured using the International Physical Activity Questionnaire, with ≥600 metabolic equivalent of task-minutes per week classified as active and < 600 as inactive. Binary logistic regression was used to compute odds ratios (OR) and 95 % confidence intervals (CI) for the A/G fat ratio and physical activity. The mediating effects of physical activity were analyzed using Process Macro Model 4. Participants in the low 50 % A/G fat ratio group had higher odds of dysmobility syndrome (crude OR = 3.500, p < 0.001; adjusted OR = 3.678, p = 0.002) and cognitive impairment (crude OR = 2.714, p = 0.005; adjusted OR = 3.293, p = 0.005) than did those in the high 50 % group, even after covariate adjustments. The inactive group had higher odds of dysmobility syndrome (crude OR = 4.185, p < 0.001; adjusted OR = 3.199, p = 0.005) and cognitive impairment (crude OR = 3.190, p = 0.001; adjusted OR = 2.551, p = 0.022) than did the active group. Mediation analysis indicated that physical activity partially mediated the association between the A/G fat ratio and dysmobility syndrome (indirect effect = -0.5099, 95 % CI = -0.9045 to -0.1786) and cognitive impairment (indirect effect = 0.1446, 95 % CI = 0.0554 to 0.2582). A lower A/G fat ratio increases the risks of dysmobility syndrome and cognitive impairment in older women; physical activity may mitigate these effects.

Background: This study examined the independent and combined associations of hand-grip strength (HGS) and arm muscle mass index with risk of non-alcoholic fatty liver disease (NAFLD) in individuals who use wheelchairs. Methods: Eighty-five individuals aged ≥ 30 years who use wheelchairs were enrolled as volunteers from sports welfare facilities for individuals with disabilities in “G” and “C” provinces. HGS was measured using a dynamometer, whereas the arm muscle mass index was assessed using a body composition analyzer. Risk of NAFLD was defined as a hepatic steatosis index (HSI) > 36 and Framingham steatosis index (FSI) ≥ 23. Results: The low-HGS group (HSI, odds ratio [OR] = 3.589, p = 0.013; FSI, OR = 2.710, p = 0.031) had a significantly higher NAFLD risk compared to the high-HGS group (reference, OR = 1). The low-arm-muscle-mass-index group showed a higher risk of NAFLD (HSI, OR = 2.762, p = 0.043; FSI, OR = 3.493, p = 0.007) compared to the high-arm-muscle-mass-index group (reference, OR = 1). Combining the low-HGS + low-arm-muscle-mass-index group (HSI, OR = 6.849, p = 0.006; FSI, OR = 6.957, p = 0.002) showed a significantly higher risk of NAFLD compared to the high-HGS + high-arm-muscle-mass-index group (reference, OR = 1), even after adjusting for covariates (HSI, OR = 7.352, p = 0.006; FSI, OR = 7.406, p = 0.003). Conclusions: Low HGS and low arm muscle mass index are independently associated with a higher risk of NAFLD in individuals who use wheelchairs, with low HGS plus low arm muscle mass index further increasing this risk.

PURPOSE: This study examined the associations between the independent and combined levels of metabolic dysfunction-associated fatty liver disease (MAFLD) and physical activity (PA) with knee osteoarthritis (KOA) in women aged ≥50 years.METHODS: A total of 6,688 women aged ≥50 years who participated in the Korea National Health and Nutrition Examination Survey (KNHANES) from 2009 to 2013 were included. The participants were classified into Case and Normal groups based on the presence of MAFLD, and into Active and Inactive groups based on compliance with the World Health Organization’s PA guidelines. Binary logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for KOA according to the independent and combined levels of MAFLD and PA.RESULTS: After adjusting for covariates, significantly higher ORs for KOA were observed in the Case group (OR=1.757, p<.001) than in the Normal and Inactive groups (OR=1.181, p<.001). In the combined analysis, all groups (Normal & Inactive: OR=1.281, p=.033; Case & Active: OR=1.672, p<.001; Case & Inactive: OR=2.079, p<.001) showed significantly higher ORs for KOA compared to the Normal & Active group.CONCLUSIONS: These findings highlight the importance of MAFLD management and regular PA for KOA prevention in middle-aged and older women. Moreover, regular PA may be an effective strategy for reducing KOA risk in individuals with MAFLD.

Minjun Kim, Hyunjun Gam, Inhwan Lee, Joonwoong Kim, Taewoong Oh. KJSM 2024;42:184-92. https://doi.org/10.5763/kjsm.2024.42.3.184