The Association Between Sarcopenia and the Strength of Peripheral and Respiratory Muscles in Elderly Individuals

Population aging is a significant global trend, with projections indicating that by 2050, 1 in 6 individuals worldwide will be over 65 years old, compared to 1 in 11 in 2019. In Turkey, the elderly population is expected to rise to 11.0% by 2025 and reach 25.6% by 2080. Sarcopenia, characterized by the progressive loss of skeletal muscle mass (SMM) and function due to aging, affects approximately 29% of older adults in community healthcare settings. It is associated with various pathophysiological processes, leading to negative health outcomes like falls and frailty. The European Working Group on Sarcopenia in Older People (EWGSOP) established diagnostic criteria for sarcopenia based on muscle mass, strength, and physical performance in 2010, later revised in 2018 (EWGSOP2), emphasizing low muscle strength as the primary diagnostic criterion. The SARC-F questionnaire is recommended for confirming sarcopenia, with a score of ≥ 4 indicating the condition. The concept of respiratory sarcopenia, introduced in 2021, refers to the loss of respiratory muscle mass and strength alongside general body sarcopenia, though measuring respiratory muscle mass can be complex. Respiratory muscle strength can be assessed through mouth pressure measurement, but a consensus on the methodology is still lacking. Overall, there is insufficient research on the relationship between peripheral and respiratory muscle weakness and sarcopenia in the elderly. This study aims to explore this relationship further.

Population aging is a global phenomenon characterized by a significant and rapid increase in the elderly population over recent years. According to World Population Prospects 2019 (United Nations, 2019), by 2050, 1 in 6 people in the world will be over the age of 65, up from 1 in 11 in 2019. It is estimated that the elderly population rate in our country will be 11.0% in 2025, 12.9% in 2030, 16.3% in 2040, 22.6% in 2060 and 25.6% in 2080. Sarcopenia is a progressive and characterized loss of skeletal muscle mass (SMM) and function associated with aging. Several prospective studies have reported that skeletal muscle mass decreases by 6% per decade after middle age. In community healthcare settings, the prevalence of sarcopenia has been reported to reach up to 29% among older adults. Sarcopenia is thought to involve a variety of pathophysiological processes, including denervation, mitochondrial dysfunction, inflammatory and hormonal changes that can lead to adverse health outcomes such as falls, functional decline, frailty, weakness, and death due to a decrease in lean body mass. The European Working Group on Sarcopenia in Older People (EWGSOP) proposed three diagnostic criteria for sarcopenia based on muscle mass, muscle strength, and physical performance in 2010. The EWGSOP proposed for sarcopenia three diagnostic criteria; low muscle mass (LMM) is defined by a SMM index of less than 8.90 kg/m2, low muscle strength (LMS) by hand-grip strength below 30 kg in men and 20 kg in women, and low physical performance (LPP) by gait speeds of less than 0.8 m/s. In 2018, The European Working Group on Sarcopenia in Older People 2 (EWGSOP2) revised the diagnostic criteria and established that low muscle strength is the primary parameter for the diagnosis of sarcopenia and the most reliable measure of muscle function. In clinical practice, when a patient shows symptoms or signs of sarcopenia (i.e. falls, feeling weak, walking slowly and difficulty getting up from a chair, or weight loss or muscle wasting), the EWGSOP2 is recommended to use the SARC-F questionnaire, which consists of five items: Strength, Assistance in walking, Rising from a chair, Climbing stairs, and Falls to confirm the diagnosis. A score of the SARC-F questionnaire ≥ 4 is considered sarcopenia. The concept of respiratory sarcopenia was first proposed in 2021 and is defined as "General body sarcopenia and low respiratory muscle mass followed by low respiratory muscle strength and/or low respiratory function." Diagnosis of respiratory sarcopenia is made by assessing respiratory muscle mass and strength. However, measuring respiratory muscle mass can often be complex, requiring advanced diagnostic equipment or techniques such as ultrasound echography and computed tomography. Assessing respiratory muscle strength is easier because it can be measured by mouth pressure measurement; however, there is no consensus yet on the exact methodology. Studies showing the relationship between peripheral muscle and respiratory muscle weakness and sarcopenia in the elderly population are insufficient. In our study, we aim to examine the relationship between sarcopenia and peripheral and respiratory muscle strength.