The influence of sarcopenia measures on balance performance based on the timed-up and go test in older adults residing in the community

INTRODUCTION

The United Nations, Department of Economic and Social Affairs (2017)^[1] projects that the number of older adults will increase from 962 million in 2017 to 2.1 billion by 2050.^[1,2] One of the prominent implications associated with an aging population is the events of fall.^[3] A recent systematic review revealed a global prevalence of falls in older adults, with the majority of fall incidents occurring among individuals aged 54–87, indicating an elevated risk of falls in the future.^[4] The World Health Organization defines a fall as the unintentional coming to rest on the ground, floor, or a lower level, excluding intentional changes in position to rest on furniture, walls, or other objects.^[5] In simpler terms, a fall occurs when an individual accidentally and sometimes traumatically ends up on the floor or at a lower level.^[6] In addition, evidence suggested that other factors that most likely cause falls, including muscle strength (MS) and gait, could cause impairment to balance performance.^[7] Balance refers to the ability of an individual to maintain their center of gravity within the base of support while reacting to a sudden disturbance triggered by external or internal factors, and is important for daily activities such as walking, standing, and even sitting.^[8]

As aging occurs, individuals will start to experience physiological changes, including the reduction of muscle mass (MM), which will likely affect their daily living activities, including balance function, especially during movement such as sit-to-stand and walking. Sarcopenia, an age-related loss of MM, is a progressive and generalized skeletal muscle disorder that affects MM, strength, and physical performance (PP),^[9] which also happens to be associated with factors that influence an individual’s balance that may lead to a fall.^[10,11] The previous studies have largely focused on the association between sarcopenia and falls in older adults, often through systematic reviews and meta-analyses.^[12,13] However, critical gaps in the literature suggest further exploration is needed. One key issue is the inconsistency in sarcopenia definitions and assessment methods across the studies. For instance, Zhang et al.^[14] highlighted that various studies have diagnosed sarcopenia using different criteria, including those from the European Working Group on Sarcopenia in Older People, the Foundation for the National Institutes of Health, and the Asian Working Group for Sarcopenia (AWGS), making it challenging to compare findings. Since cut-off points depend on measurements obtained from various instruments that may not be readily accessible, a simple questionnaire was proposed as an alternative for sarcopenia screening.^[15] The SARC-F is widely recognized for its efficiency and alignment with multiple diagnostic algorithms and incorporates MM, MS, and PP measures, as recommended by most of the working group for sarcopenia, including the latest AWGS criteria.^[12] SARC-F is a 5-item questionnaire that assesses sarcopenia based on participants’ perceptions of their strength, walking ability, rising from a chair, stair-climbing, and falls. SARC-F is believed to have good validity and consistency in identifying people at risk of sarcopenia.^[9] Apart from its simplicity and being well recognized among different countries, it measures the most crucial movements relating to balance in combination with the other tools, including MM, strength, and PP as recommended by the AWGS. Thus, SARC-F may potentially be associated with individuals’ balance performance.

Sarcopenia causes a loss of MM and strength, which further causes impairments to one’s balance performance. These issues, in turn, can raise the risk of falling. Thus, exploring the correlation of sarcopenia parameters with balance performance is crucial to better understand and address this important public health issue. Since most of the country is predicted to reach aging nations in the near future, thus, determining how sarcopenia can affect balance is crucial to tackle this issue by empowering more research to understand the influence and how to prevent the risk of falls in the older population.

Hence, the primary objective of the present study is to explore the influence of sarcopenia measures on balance performance in older adults residing in the community.

MATERIALS AND METHODS

This is a cross-sectional study where the sample population was recruited from Bangi, Kajang, Semenyih, Hulu Selangor, Beranang, and Sabak Bernam in Selangor, Malaysia, using purposive sampling. The sample size calculation was conducted using G*Power 3.1.9.2 for an Analysis of covariance statistical test with fixed effects, main effects, and interactions. An effect size of 0.25, representing a medium effect size per Cohen’s guidelines, was chosen to balance statistical power and feasibility in community settings. The significance level (a) was set at 0.05, with a statistical power (1 - b) of 0.90 to ensure a 90% probability of correctly rejecting the null hypothesis. The sample size calculation yielded that about 338 participants are required to detect a medium effect size with high confidence and precision.

Participants underwent initial eligibility screening based on the predetermined criteria. The inclusion criteria were people aged 60 and above, of both genders, with no recent acute illnesses (such as a stroke or Parkinson’s disease within the past 6 months) and no cognitive impairment (based on a Mini-Cog test score of >4). The exclusion criteria were significant hypertension (systolic >180 at the time of evaluation), inability to comprehend the study procedures, a history of heart problems, gastrointestinal tract disease, musculoskeletal injuries (such as bone fractures or sprains within the past 6 months), and recent surgery (within the past 6 months).

Participants who met the inclusion criteria proceeded to the data collection procedures. This phase began with the completion of self-reported questionnaires. Participants answered the SARC-F questionnaire to assess sarcopenia-related symptoms, with provided assistance mainly to those who required help due to reading difficulties or other impairments. The research ethical approval for a study involving human subjects was obtained from the Research Ethics Committee, UiTM (Approval Number: REC/02/2021 (MR/81). Participants’ consent to participate and for data publication in a journal article was obtained before data collection.

RESULTS

Table 1 summarizes the overall participants’ characteristics. The total sample size was 315, which included 167 females (53%) and 148 males (47%). The mean age was 68.05 years (SD = 5.98), ranging from 60 to 90 years old. About 133 (42.2%) of participants presented with low balance performance.

Table 2 shows the result of the independent t-tests for the mean differences and the Chi-square test for frequency differences of sarcopenia parameters between participants with low and normal balance performance. The independent t-tests show that all sarcopenia parameters are significantly different between participants with normal and low balance performance (All P < 0.05), except for MM (P = 0.057). On the other hand, the results for the Chi-square tests indicate that all sarcopenia parameters are significantly different between participants with low and normal balance performance.

Table 3 describes the results of the binary logistic regression analysis. Data were presented analyzed through the values of odd ratio (OR) and confidence interval (CI).

For SARC-F, both models show a strong, significant negative association (unadjusted OR = 0.40; adjusted OR = 0.313), indicating higher SARC-F scores significantly decrease the odds of better balance performance. MM is non-significant in the unadjusted model (OR = 0.87, P = 0.058) but significant in the adjusted model (OR = 0.60), indicating lower MM reduces the likelihood of better balance. Muscle strength is positively significant associated in both models (unadjusted OR = 1.063; adjusted OR = 1.08), which means higher muscle strength increases the odds of better balance performance. PP shows a significant negative association across models (unadjusted OR = 0.77; adjusted OR = 0.76), describing poorer PP reducing balance performance. Except for MM, all outcomes were significantly associated with TUG, with P < 0.01.

DISCUSSION

In the present study, findings showed that among various measures of sarcopenia, only SARC-F, muscle strength, and PPs were independent predictors of falls among older individuals living in the community. However, after controlling for the effects of age and gender, all sarcopenia parameters were associated with balance performance, which includes MM.

Notably, SARC-F was highly correlated to balance performance, suggesting that it can be used as a straightforward screening measure for both sarcopenia and balance performance.^[27] Similarly, our study revealed the association of SARC-F to balance performance as assessed through TUG (OR: 0.4 [95% CI: 0.33,0.48]). SARC-F’s validity and consistency in identifying individuals at risk of sarcopenia have been documented,^[12] making it an efficient tool for case finding. It was also found that SARC-F score of 4 or higher independently predicts fall risk with a sensitivity of 44.44% and a specificity of 89.26%, although with the use of different balance assessment tools.^[27] Thus, integrating SARC-F could be beneficial in indirectly measuring changes in an individual’s balance performance in a short time. While SARC-F is an efficient tool for detecting sarcopenia symptoms within a short time, its reliance on subjective self-reporting poses a risk of bias. Therefore, it is recommended to combine SARC-F with objective assessment tools, such as muscle strength and PP measures, to enhance accuracy and reliability.

Muscle strength emerged as a critical factor impacting both dynamic and static balance and was identified as a significant predictor of fall risk in older adults.^[28] Individuals at high risk of falls exhibited lower muscle strength and poorer PP compared to those at low risk, as supported in the previous studies.^[29] These findings highlight the importance of maintaining muscle strength and overall physical fitness to prevent falls. Improving muscle strength through targeted exercises, balance training, and resistance training may help to improve their balance and reduce the risk of falls.^[30]

Muscle health, including MM, strength, and PP, emerged as significant factors associated with falls. Individuals at high fall risk displayed lower muscle strength and poorer PP, reiterating the significance of maintaining muscle strength and overall fitness to prevent falls. Older adults will slowly encounter a reduction of muscle strength, which causes them to have difficulties in movement.^[31] As individuals age, they will likely experience a decline in MM, which also impacts their muscle strength.^[32,33] This decline in strength is primarily attributed to a reduction in Type-II muscle fibers, also known as fast-twitch fibers, which are responsible for generating muscle tension. These fibers are larger and contract more quickly, thus contributing to an individual’s overall strength.^[34,35] However, our study did not include a specific assessment to directly evaluate muscle fiber reduction, limiting our ability to confirm this aspect. Despite that, measuring muscle strength is encouraged to assess outcomes or predict potential limitations that may interfere with daily activities, as its decline has been identified as an independent predictor of poor balance performance in our study (OR: 1.06 [95% CI: 1.04, 1.09]).

PP was observed to have an association with balance performance.^[36,37,39] Physical performance encompasses objectively measured whole-body functions related to locomotion,^[9] where the 5 times sit-to-stand test was employed in this study. It is a reliable and valid clinical tool to gauge lower extremity strength and their overall performance.^[20] Sarcopenia involves physiological and functional deterioration, including PP,^[9] which may increase the fall-related aspects. The reduction in MM can lead to diminished muscle strength and affect limb proprioception, disrupting balance mechanisms and influencing an individual’s PP.^[10] Often, physical performance is related to the ability to sustain impact on the lower limbs, making most of the variables used involve gait speeds.^[12] PP is also critically related to muscle strength, which contributes to the fall-related aspects as it works to maintain balance and stability, where weaker muscles can compromise an individual’s ability to react to sudden changes in posture or prevent a fall. Thus, a reduction in physical performance has consistently influenced balance performance in older adults.^[9]

It is noted that sarcopenia involves negative changes in skeletal MM, strength, and PP,^[12] contributing to adverse outcomes including reduced balance performance and increased fall risk.^[38,39] However, the present study observed a lack of association between sarcopenia based on MM measured using the BIA with fall incidence. This might be due to the methodological variation, where other study implies the usage of other high-advanced tools such as dual-energy x-ray absorptiometry, which have better sensitivity when measuring MM. Intriguingly, the study found that participants at high fall risk had higher MM, potentially indicating a complex relationship between increased MM and falls, which might involve factors such as muscle quality and overall physical fitness.

Another aspect that needs to be focused on when relating sarcopenia with balance performance is neuromuscular control, which plays a crucial role in maintaining postural stability, muscle function, and movement coordination. As aging and sarcopenia occur, they significantly affect the components required to ensure a good balance performance, including weakened muscle responses, impaired balance, and increased fall risk.^[12,40] The decline in neuromuscular function is influenced by multiple factors, including the loss of motor units, reduced proprioception, and hormonal changes.^[41]

Aging causes numerous hormonal and neuronal changes, implying that multiple genes must be differentially expressed.^[40] This results in decreased hypothalamic and peripheral receptor sensitivity, leading to energy imbalances, immune system weakening through immunosenescence, reduced reproductive ability, and diminished physiological adaptability.^[41] In addition, the reduction in sex-related hormone secretion, such as estrogen after menopause, is associated with osteoporosis, further contributing to decreased muscle strength and movement ability.^[42]

Physiological changes with advancing age are characterized by a decline in both the size and number of muscle fibers, particularly Type II (fast-twitch) fibers, which are responsible for quick, powerful contractions.^[34,35] Type II muscle fibers are essential for strength and rapid force generation, and their reduction leads to decreased neuromuscular efficiency, slower reaction times, and impaired postural control.^[43] Satellite cells, which play a critical role in muscle regeneration, also decline with age, reducing the ability to repair and regenerate muscle fibers.^[44] The loss of these cells further impairs neuromuscular function, slowing the signal conduction between muscle bundles and compromising overall muscle strength and coordination.^[45]

As the loss of MM progresses, individuals also experience a reduction in muscle strength, primarily due to the deterioration of Type II fibers, which are essential for performing movements against resistance.^[46] With fewer motor units available to innervate muscles, neuromuscular transmission weakens, leading to diminished movement efficiency and a greater reliance on compensatory mechanisms to maintain balance. In addition, proprioception, the body’s ability to sense movement and spatial positioning, deteriorates with aging, affecting neuromuscular control and balance regulation. Sensory degradation in muscle spindles and joint receptors slows neuromuscular responses, increasing postural sway and fall risk.^[34]

Given the critical role of neuromuscular control in maintaining balance and mobility, targeted interventions such as resistance training, balance exercises, and neuromuscular stimulation therapies should be implemented into the clinical practice to enhance muscle activation and functional connectivity.

Physical inactivity is a significant risk factor for the deterioration of musculoskeletal health, as well as for the increased risk of non-communicable diseases, including sarcopenia.^[47] Therefore, promoting an active lifestyle, particularly among the older population, is essential to maintaining stable balance performance. Muscle fatigue too can notably impair PP, which, in turn, affects balance and increases the risk of falls in older adults. A study found that expectations regarding supplementation (such as caffeine or lactic acid) could influence perceived exertion and endurance, indicating that psychological factors also contribute to performance outcomes.^[48]

Another important factor influencing balance performance is low Vitamin D levels, which are associated with an increased risk of various health issues, including cardiovascular disease.^[49] However, Vitamin D was not measured in the present study. Since Vitamin D plays a critical role in muscle function and bone health, it is recommended that future research includes Vitamin D assessments to explore how deficiencies may exacerbate sarcopenia and elevate fall risk among older adults.

Knee osteoarthritis (OA)-related pain is another major factor affecting balance performance. This condition is widespread among older adults and significantly impairs both balance and mobility. Knee OA often results in generalized pain, swelling, and stiffness, which can disrupt balance and increase the risk of falls. It is therefore crucial to consider knee OA as a variable in future studies.^[50]

The limitations of this investigation highlighted the small sample size of the study, initially posing a challenge that made it difficult to categorize participants accurately according to their severity levels. Because measurements were made at a single moment in time, the cross-sectional design of this study made it impossible to determine a cause-and-effect link between sarcopenia indices and balance performance. To fully comprehend the causal-and-effect link between these factors and to determine strategies for addressing and preventing falls in the future for older populations, it is highly recommended that more longitudinal data reflective of sarcopenia and balance performances be included. Finally, this study highlights the importance of including sarcopenia markers in fall assessments, such as the use of SARC-F and measurements of MM, strength, and PP. However, it is essential to ensure comprehensive training for those conducting these assessments, as improper execution could affect the outcomes.^[51]

CONCLUSION

The present study shows that sarcopenia parameters, particularly SARC-F, muscle strength, and PP are significantly associated with balance performance in older adults, with MM only significantly associated after controlling for age and gender. The current findings suggest that early screening of sarcopenia parameters, mainly muscle strength and PP may potentially enhance balance performance in older adults. Future studies should explore the longitudinal impacts of intervention to confirm their effectiveness in balance improvement and fall risk reduction in the older population.