Elevated serum leptin levels are associated with low muscle strength and muscle quality in male patients undergoing chronic hemodialysis

Higher Levels of Serum Leptin Are Linked with a Reduction in Gait Stability: A Sex-Based Association

Gait stability prevents falls and injuries during physical activities. Muscle strength, aging, and co-existing chronic diseases are factors that affect gait stability. Leptin is an adipokine with pro-inflammatory properties. Several reports demonstrated an association between serum leptin and a reduction in muscle strength. Given the above relationships, we hypothesized that serum leptin could be associated with gait stability. To test this, 146 apparently healthy university students were recruited. Data collection involved anthropometric measurements, physical activity (PA) data, gait parameters, and serum leptin levels. A gait instability index was derived from the percentages of double support time and walking asymmetry (WA) collected from smartphones. Females demonstrated higher leptin levels and WA despite a lower body mass index (BMI). Lower PA levels were also observed among females. Leptin levels were negatively correlated with WA, step count, and vigorous PA (p < 0.05). These correlations remained significant following correction for leptin by BMI. Using logistic regression, a higher leptin-to-BMI ratio was associated with high gait instability (OR = 9.97, 95%CI: 4.17-23.84, p < 0.001). After stratification by sex, this association was only evident among females (OR = 6.09, 95%CI: 1.04-35.56, p = 0.045). These findings suggest a sex-based association between serum leptin and gait stability among apparently healthy students.

Role of adipokines in sarcopenia

ABSTRACT

Sarcopenia is an age-related disease that mainly involves decreases in muscle mass, muscle strength and muscle function. At the same time, the body fat content increases with aging, especially the visceral fat content. Adipose tissue is an endocrine organ that secretes biologically active factors called adipokines, which act on local and distant tissues. Studies have revealed that some adipokines exert regulatory effects on muscle, such as higher serum leptin levels causing a decrease in muscle function and adiponectin inhibits the transcriptional activity of Forkhead box O3 (FoxO3) by activating peroxisome proliferators-activated receptor-γ coactivator -1α (PGC-1α) and sensitizing cells to insulin, thereby repressing atrophy-related genes (atrogin-1 and muscle RING finger 1 [MuRF1]) to prevent the loss of muscle mass. Here, we describe the effects on muscle of adipokines produced by adipose tissue, such as leptin, adiponectin, resistin, mucin and lipocalin-2, and discuss the importance of these adipokines for understanding the development of sarcopenia.

Deciphering the "obesity paradox" in the elderly: A systematic review and meta-analysis of sarcopenic obesity

Aging and obesity are two global concerns in public health. Sarcopenic obesity (SO), defined as the combination of age-related sarcopenia and obesity, has become a pressing issue. This systematic review and meta-analysis summarize the current clinical evidence relevant to SO. PubMed, Embase, and Web of Science were searched, and 106 clinical studies with 167,151 elderlies were included. The estimated prevalence of SO was 9% in both men and women. Obesity was associated with 34% reduced risk of sarcopenia (odds ratio [OR] 0.66, 95% CI 0.48-0.91; p < 0.001). The pooled hazard ratio (HR) of all-cause mortality was 1.51 (95% CI 1.14-2.02; p < 0.001) for people with SO compared with healthy individuals. SO was associated with increased risk of cardiovascular disease and related mortality, metabolic disorders, cognitive impairment, arthritis, functional limitation, and lung diseases (all ORs > 1.0, p < 0.05). The attenuated risk of sarcopenia in elderlies with obesity ("obesity paradox") was dependent on higher muscle mass and strength. Apart from unifying the diagnosis of SO, more research is needed to subphenotype people with obesity and sarcopenia for individualized treatment. Meanwhile, the maintenance of proper body composition of muscle and fat may delay or attenuate the adverse outcomes of aging.

Age, hemodialysis time, gait speed, but not mortality, are associated with muscle quality index in end-stage renal disease

BACKGROUND

The muscle quality index (MQI) has proven to be an interesting clinical measurement in hemodialysis (HD) patients. In clinical practice, its interpretation can be biased by fat mass (FM) distribution. This study aims to explore the arm MQI association with body composition, clinical factors, and mortality.

METHODS

It was analytical longitudinal and exploratory, that included patients from two-center, over 18 years old, of both genders in treatment by HD. The follow-up period was 32 months, and mortality was the clinical outcome. Demographical and clinical data were collected in the patient's medical records. Body composition was evaluated using octopolar multi-frequency bioelectrical impedance analysis (MF-BIA). Handgrip strength (HGS) was measured by a dynamometer and the time required to walk 3 m was applied to obtain gait speed. The baseline associations with MQI (HGS/arm muscle mass) were examined by multivariate linear regression. Cox regressions evaluated the associations with mortality.

RESULTS

A total of 97 patients in HD were included. Mean age was 50.93 ± 14.10 years, 71.13 % were male. Age (β = -0,096, p = 0.024), HD time (β = -0.023, p = 0.032), total skeletal muscle mass (β = -0.475, p < 0.001) were inversely associated with MQI and gait speed had a direct association with MQI (β = 8514, p = 0.002). The prevalence of mortality was 29.76 %, of which 37.29 % were men (p = 0.020). Low MQI was not associated with mortality (Hz = 0.80, CI95 % = 0.34; 1.91, p = 0.629).

CONCLUSION

The arm MQI was associated with an indicator of general functional capacity (gait speed), but was not associated with fat measures in baseline and mortality after 32 months of follow-up.

Higher Serum Leptin Levels are Associated with a Reduced Risk of Sarcopenia but a Higher Risk of Dynapenia Among Older Adults

Background

Leptin plays an important role in regulating the energy homeostasis of fat and muscle. Paradoxical findings existed between serum leptin levels and muscle health conditions. Here, we aimed to investigate the relationship between serum leptin levels and the risk of sarcopenia or dynapenia among older adults.

Methods

Adults aged 65 and older living in the community were recruited at annual health checkups. Body composition, gait speed, and handgrip strength were examined. The cutoff values of muscle mass and strength to define sarcopenia and dynapenia were based on the consensus by the Asia Working Group of Sarcopenia in 2019. Serum leptin level was measured by an immunoassay.

Results

Four hundred sixty participants (55.65% females) were enrolled. There were 16.08% and 23.91% with sarcopenia and dynapenia, respectively. Higher serum leptin levels were positively associated with muscle and fat mass but negatively associated with handgrip strength and gait speed for both sexes. In the logistic regression models adjusted for various confounders, a higher serum leptin level was associated with an increased risk of dynapenia with dose-response effects among both male and female participants (odds ratio [OR]=3.74, 95% confidence interval [CI]= 0.99–14.17; OR= 3.32, 95% CI=1.03–10.74, respectively), and a positive trend existed in both genders (p for trend=0.040 and 0.042, respectively). In contrast, a higher leptin level was associated with a reduced risk of sarcopenia with dose-response trends for both sexes (OR= 0.06, 95% CI=0.01–0.48; OR= 0.26, 95% CI=0.06–1.17, respectively) in models of multivariate logistic regression analyses, and a negative trend existed in both genders (p for trend = 0.002 and 0.023, respectively).

Conclusion

A positive trend existed between the serum leptin level and the dynapenia risk, whereas it revealed a negative trend in the serum leptin level and sarcopenia risk in both male and female elderly individuals. The biological mechanisms underlying its negative association with muscle strength but its positive association with muscle mass warrants further investigation.