In 2022, there were 4.1 million or 17.5% adults older than 65 years old living in Taiwan (1). Furthermore, it is estimated that the proportion of Taiwanese older adults could be higher than 20% by 2025, which refers to a “superaged society.” Aging is strongly associated with a decrease in muscle strength and muscle mass, resulting in physical dysfunction (e.g., gait speed agility and balance), falling and deterioration in quality of life (2, 3). Therefore, successful aging is an important issue for the older adult population in Taiwan to promote health and maintain active engagement with life (4, 5).

Falls are the leading cause of fractures and even deaths among older adult adults (6). The most common fall-induced fractures occur at the hip, spine, upper arm and forearm (7). Of these fractures, hip fractures have serious consequences, such as reduced mobility and independence and high mortality in the first three months (3, 8). Numerous studies indicated that older adult fallers are characterized by lower muscle strength of the lower extremities and slower walking speeds (6, 9–12). A similar study reported that the main determinants for recurrent falls included fall history, muscle strength, abnormal postural sway (e.g., balance and gait disturbances), and depression (8, 13–15).

It has been shown that the one-leg stance with eye open test is a readily applicable screening tool in clinical and geriatric environments, used to assess postural steadiness during static positions (16); failing to pass a 5-s threshold could indicate functional impairment, thereby heightening the risk of falls (17). Khanal et al. suggested that older adult individuals with a one-leg standing test below the 55-s threshold (the sum of both legs) have low muscle mass and a high risk of developing sarcopenia (18). A study indicated that independent older adult adults have higher walking speeds than dependent older adults, such as those living in nursing or rest homes (19). In addition, the 8-foot up-and-go test has been successfully associated with dynamic balance, agility and walking speed performance, as well as fall risk, in the older adult population (2). Thus, older adult adults with good static and dynamic balance and quick walking speeds might have better independence and a lower risk of sarcopenia and falling. This was supported by past research, which found that the risk of falls in the older adult was associated with low muscle strength and physical fitness, but not with low muscle mass (20).

Taiwan is not only a highly technologically developed country but also an aged society. To our knowledge, no study has yet reported the relationship between lower extremity muscle strength and static and dynamic balance among Taiwanese older populations. Therefore, in the present study, we aimed to investigate the association between lower-limb muscle strength performance and static and dynamic balance control among older adults in Taiwan.

Table 2 shows the association of continuous or categorical (quartiles) variables in lower extremity muscle strength performance with static and dynamic balance control measures. For both genders, continuous variables in lower extremity muscle strength performance were significantly associated with static and dynamic balance control measures. Moreover, whether the participant was male or female, after adjusting for BMI, education, monthly income, and marital and relationship status, there was still significant, positive regression coefficient values in static balance measures (Men: β = 0.553, p ≤ 0.0001; Women: β = 0.503, p ≤ 0.0001) and negative regression coefficient values in dynamic measures (Men: β = −0.206, p ≤ 0.0001; Women: β = −0.222, p ≤ 0.0001).

For both genders, categorical (quartiles) variables in lower extremity muscle strength performance were significantly associated with static and dynamic balance control measures. Increased lower-limb muscle strength levels were significantly associated with static balance in men (Q2: β = 2.539, p ≤ 0.0001; Q3: β = 4.590, p ≤ 0.0001; Q4: β = 7.700, p ≤ 0.0001) and women (Q2: β = 2.022, p ≤ 0.0001; Q3: β = 4.179, p ≤ 0.0001; Q4: β = 6.920, p ≤ 0.0001) after adjusting for potential confounders. In addition, we observed that increased lower-limb muscle strength levels were significantly associated with dynamic balance in men (Q2: β = −1.661, p ≤ 0.0001; Q3: β = −2.434, p ≤ 0.0001; Q4: β = −3.091, p ≤ 0.0001) and women (Q2: β = −1.660, p ≤ 0.0001; Q3: β = −2.548, p ≤ 0.0001; Q4: β = −3.196, p ≤ 0.0001) after adjusting for potential confounders.

In this study, we analyzed the relationship between lower-limb muscle strength performance and static and dynamic balance control using data from 20,846 Taiwanese older adult adults. The main findings of this study were as follows: First, lower-limb muscle strength was positively associated with static and dynamic balance performance, and we also observed dose–response relationships in the aforementioned variables; and second, higher levels of lower-limb muscle strength were associated with higher regular exercise and a lower risk of abdominal obesity. These findings suggest that older adult adults with good static and dynamic balance and quick walking speeds are more independent and have a reduced risk of sarcopenia and falling.

It has been reported that adults who perform ≥150 min/week of moderate-intensity physical activity (e.g., cleaning, gardening, walking and yoga), which is associated with lower rates of cardiovascular diseases and premature mortality, are considered regular exercisers (33–35). In addition, Chen et al. found that higher levels of relative grip strength were associated with a lower risk of abdominal obesity and cardiorespiratory fitness (36). In this study, we observed that approximately 75% of older adults were classified as nonregular exercisers in Taiwan, and higher levels of nonregular exercise were associated with lower 30-s chair stand performance and higher body mass index and waist-to-hip ratio. Our findings suggested that older adult adults who exercise regularly may have better lower extremity muscle strength performance and are less at risk for abdominal obesity compared to those who do not exercise regularly. Consistent with previous findings, the results of this study suggest that individuals with weaker leg strength have a higher rate of risk for disease (e.g., metabolic syndrome) (37, 38).

A previous study indicated that older fallers are characterized by lower muscular strength and aerobic endurance performance (chair stand test and 6-min walk test, respectively) than nonfalling older adult men, whereas agility and dynamic balance (8-foot up-and-go test) tended to differ (p = 0.075) between the two groups (8). These disparate results could be the result of the sizes of and differences in sample sizes (fallers, n = 16 vs. nonfallers, n = 50). In the present study, we found that lower-limb muscle strength was positively associated with one-leg stance with the eye open test and 8-foot up-and-go test performance in both genders. A similar study indicated that a one-leg stance with the eye open test was associated with hip fracture risk; for example, the risk of hip fracture was 5% lower with a 1-s longer one-leg stance with the eye open test (39). We suggest that older adult adults with good lower-extremity muscle strength (30-s chair stand test, ≥ 12 repetitions) could increase static and dynamic balance, as well as prevent falling, thereby reducing the risk of fracture and improving quality of life.

Notably, this study is the first to examine the dose–response relationships between lower-limb muscle strength with the one-leg stance with the eye open test and the 8-foot up-and-go test after adjusting for confounding factors (e.g., age, BMI, educational levels, monthly income levels) among Taiwanese older adults. We observed that higher levels of lower-limb muscle strength were associated with higher agility and better static and dynamic balance performance in both genders. In addition, this study took as its starting point the global goal of healthy aging, which makes the study of the health of older adults in Taiwan a critical issue given that Taiwan will become a super-aged society by 2025 and the proportion of older adults in the population will increase more rapidly than in other countries.

The present study has some limitations. First, our questionnaire did not include fall history, physical activity, cardiovascular disease, hypertension or sarcopenia, which could interfere with muscle strength, balance and mobility performance. Second, this study was a cross-sectional study, and no cause and effect relationships can be guaranteed. Future studies should be conducted with a longitudinal study design to understand the cause and effect relationship between thigh muscle strength and static and dynamic balance performance in Taiwanese older adult individuals.

This study demonstrated that lower-limb muscle strength was the most important factor, as it was an improved method for static and dynamic balance control in both genders. As Taiwan has one of the highest aging rates in the world, there is a high demand for comprehensive aging-related policies. Therefore, by providing useful information on personal balance and fall risk to guide the development of appropriate prevention and rehabilitation programs, this study allows older adults to self-assess their balance by conducting tests and taking appropriate actions to reduce fall risk, such as engaging in appropriate exercise and balance training.

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/supplementary material.

The studies involving humans were approved by Institutional Review Board of Fu Jen Catholic University (FJU-IRB C110113). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

P-CY and T-SL participated in the design, conducted the statistical analyses, and interpreted the data, drafted and revised the manuscript. D-KS supervised the study, assisted in data interpretation, and critically reviewed the manuscript. C-CH helped to manage and analyze the data. All authors contributed to the article and approved the submitted version.