Sarcopenia is a progressive and widespread skeletal muscle disease and the risk increases with age (1). It is estimated that sarcopenia has impacted 10–16% of older adults worldwide (2). Sarcopenia increases the risk of adverse consequences such as falls, fractures, physical disabilities, and death in older adults which causes a substantial increase in economic burden on patients’ families and society (3).

Low muscle strength is the primary parameter of sarcopenia because it is the most reliable indicator of muscle function (4). Grip strength is one of the most common muscle strength markers in clinical and research settings (5). Grip strength and sarcopenia in older adults have important implications for predicting multiple diseases and the risk of death. A large-sample prospective study of UK Biobank participants found that lower grip strength was associated with a higher risk of developing severe non-alcoholic fatty liver disease (3). Another study in community-dwelling older adults showed that screening for sarcopenia severity and low muscle strength may be used to identify the risk of cognitive impairment (6). In addition, Takahashi et al. (7) indicated that sarcopenia was associated with incident all-cause mortality in older outpatients with type 2 diabetes mellitus (T2DM).

Muscle activity depends on glucose metabolism, and insulin resistance (IR) can decrease the muscle’s ability to utilize glucose, reduce intracellular energy production, and weaken muscle strength (8). The homeostasis model assessment of insulin resistance (HOMA-IR) is a traditional IR index with limited clinical application (9). However, the triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio has been suggested as a new alternative IR index in recent years (10), which has been also applied to research studies in diabetes mellitus (DM) (11) and cardiovascular disease (CVD) (12). A recent study in older Korean men showed that the TG/HDL ratio was positively related to a higher risk of sarcopenia (13). Another study in community-dwelling Chinese adults also found a negative association between the sarcopenia occurrence rate and the TG/HDL-C ratio (14).

Measures of grip strength are convenient assessments of strength capacity and a reliable measure of muscle function (15, 16). However, studies on the relationship between the TG/HDL-C ratio and muscle function are still absent, and the results on the role of the TG/HDL-C ratio in sarcopenia were inconsistent. Herein, this study aims to explore the association between TG/HDL-C ratio and relative grip strength in individuals aged ≥60 years old and further discusses this relationship in those who are of different genders as well as the complications. We hope that this study can provide some references for the prevention and management of sarcopenia in older adult populations.

In this study, we explored the association between the TG/HDL-C ratio and the relative grip strength in older adults. The results showed that after adjusting for the covariates including age, gender, race, marital status, physical activity, DM, CVD, arthritis, CKD, and albumin, the TG/HDL-C ratio was negatively associated with the relative grip strength. This relationship was also found in those who were women, not having DM, and having CVD.

The TG/HDL-C ratio can reflect the comprehensive level of lipid metabolism in the body and has been indicated as a risk factor in some diseases (25–27). Liu et al. (11) found that an increased TG/HDL-C ratio indicated a greater risk of new-onset T2DM and may be a simple but effective indicator in predicting T2DM in older adults. Wu et al. (28) showed that the TG/HDL-C ratio was significantly associated with arterial stiffness progression in hypertensive population. Kim et al. (29) considered that higher TG/HDL-C ratios were positively associated with CKD development in men, while middle levels of TG/HDL ratios reduced the CKD incidence in women. However, to the best of our knowledge, no previous study has explored the relationship between the TG/HDL-C ratio and grip strength. A MONET study on overweight and obese postmenopausal women showed that the TG/HDL-C ratio was significantly correlated with muscle strength (30). Wang et al. (14) found a negative association between sarcopenia and TG/HDL-C ratio in community-dwelling adults in China. In addition, Lin et al. (31) studied older patients with DM in China and found that there was a negative association between TG/HDL-C ratio and sarcopenia, indicating that a higher TG/HDL-C ratio was associated with better muscle status. Differently, in the current study, we found that the TG/HDL-C ratio was negatively associated with the relative grip strength in adults aged ≥60 years old, which indicated that the TG/HDL-C ratio may be suggested to be controlled at an appropriate level in clinical practice and may benefit to prevent and control sarcopenia in older adults. However, the causal association between the TG/HDL-C ratio and grip strength and the role of the TG/HDL-C ratio in sarcopenia needs further exploration.

The potential mechanism to explain the role of the TG/HDL-C ratio in grip strength and sarcopenia in older adults has been unclear. Based on the data from the 2019 Korea National Health and Nutrition Examination Survey, a study showed that TG was significantly lower while HDL-C was significantly higher in the participants with high muscle strength than in those with low muscle strength (32). Under healthy conditions, intramuscular TG can be utilized as a readily available fuel source for muscle contraction during physical exercise; however, it can also be associated with pathological conditions, such as IR and sarcopenia (33). In skeletal muscle, lipids in the plasma membrane can induce intracellular signal transduction such as releasing Ca²⁺ from the endoplasmic reticulum (ER), which has an important function in muscle contraction (34). A study conducted by Park et al. (35) showed that when the level of physical activity increased, the prevalence of sarcopenia decreased, and above moderate-active physical activity levels were associated with higher HDL-C than low-active physical activity. In addition, patients with T2DM are prone to lose muscle mass more rapidly, thus becoming more susceptible to IR than the general population (36). Therapeutics for patients with T2DM or other dysmetabolic conditions may affect the body composition, for example, the muscle strength and the muscle quality index (37). According to these findings, we speculated that disturbance in lipid metabolism including an increase in TG level and decrease in HDL-C level may contribute to reduced muscle strength during aging, which played an important role in the development of sarcopenia. In addition, physical activities in older adults can help improve musculoskeletal health by increasing muscle strength and flexibility, which are factors related to sarcopenia. We concluded that older adults should control TG/HDL-C levels within the appropriate range and appropriately strengthen exercise to prevent the occurrence of sarcopenia under the guidance of physicians.

We further explored the association between TG/HDL-C ratio and relative grip strength in gender, DM, CVD, and arthritis subgroups. Subgroup analyses showed that increased TG/HDL-C ratio was associated with decreased relative grip strength in older adults who were women, without DM, or with CVD. Gender is a risk factor for sarcopenia (38). A previous study indicated that muscle strength correlates with total body bone mineral density, which was significant in women but not in men (39). Kim et al. (40) investigated the changes in metabolic indices of serum lipid level and serum glucose level according to grip strength in postmenopausal women and found that with a high relative grip strength, the TG level decreased while the HDL-C level increased. The difference in the age-related changes in factors such as physical activity, nutritional status, sex hormones, and growth hormones which affect muscle quality/quantity between women and men may contribute to the gender difference in muscle (41). Insulin plays an important role in the anabolic action of skeletal muscle, and it can be progressively lost in T2DM, which may induce decreased protein synthesis and increased protein degradation, leading to a reduction in muscle strength (42). Increased TG/HDL-C ratio indicating a greater risk of new-onset T2DM is well known so DM patients may follow doctor’s advice or spontaneously control their TG and HDL-C levels through medication or other means (11). This may explain why this relationship was more significant among the non-DM population. CVD is a chronic comorbidity that often exacerbates sarcopenia (43). Studies have reported an increased prevalence of CVD risk factors, such as DM, hypertension, dyslipidemia, and metabolic syndrome, which are related to lowered skeletal muscle mass (44, 45). In addition, the TG/HDL-C ratio was associated with arterial stiffness progression in patients with hypertension (28). The underlying mechanisms of the relationship between sarcopenia and CVD are multifactorial, involving pathophysiological changes such as muscle mitochondria dysfunction, oxidative stress, multiple metabolic disorders, malnutrition, and insufficient physical activity (46, 47). Our results may be a supplement to previous reports, and we found that in older adults who had CVD, the TG/HDL-C ratio was negatively associated with the relative grip strength, indicating that it was meaningful to focus on this ratio in patients with CVD to prevent sarcopenia. We concluded that serum TG/HDL-C ratio level should be taken into consideration for the evaluation and dynamic monitoring for grip strength and sarcopenia in older adults, especially those who have different clinical chronic diseases.

With the increase in the TG/HDL-C ratio, the relative grip strength of older adults decreased significantly, indicating that the TG/HDL-C ratio should be closely monitored in the older adult population because it may associated with the prevention and control of sarcopenia.

Publicly available datasets were analyzed in this study. This data can be found here: the NHANES database, https://wwwn.cdc.gov/nchs/nhanes/.

The requirement of ethical approval was waived by The First Affiliated Hospital of Traditional Chinese Medicine of Chengdu Medical College for the studies involving humans because Since NHANES was approved by the Institutional Review Board of the NCHS of the US Centers for Disease Control and Prevention and the data were publicly available, no ethical approval of our IRB was required. The studies were conducted in accordance with the local legislation and institutional requirements. The ethics committee/institutional review board also waived the requirement of written informed consent for participation from the participants or the participants’ legal guardians/next of kin because Since NHANES was approved by the Institutional Review Board of the NCHS of the US Centers for Disease Control and Prevention and the data were publicly available, no ethical approval of our IRB was required.

YH designed the study, wrote the manuscript, critically reviewed, edited, and approved the manuscript. JL and YL collected, analyzed, and interpreted the data. All authors contributed to the article and approved the submitted version.