In this open access paper, researchers speculate on the common mechanisms underlying the correlation between reduced grip strength and chronic lung disease in old age. The many, complex, and diverse manifestations of aging emerge from a much smaller, simpler set of root causes. Simple forms of damage applied to a very complex system necessarily produce very complex outcomes. Nonetheless, the incidence of many of those outcomes, even when very different from one another, will correlate because they depend to a sizable degree on the same forms of underlying damage.
The term "sarcopenia" was first introduced to describe the progressive age-related loss of muscle mass and is correlated with poor health-related quality of life. In this context, the handgrip dynamometer (HGD) is a useful tool to evaluate muscle strength because it provides simple, fast, reliable, and standardized measurements of total muscle strength. In addition, handgrip strength (HGS) is considered an important measure to diagnose dynapenia because low HGS is a robust predictor of low muscle mass and a clinical marker of poor physical performance.
In the respiratory system, the incidence of chronic lung diseases (CLDs) is comparatively higher in individuals aged 65 and older. HGS is an indicator of overall physical capacity. It is not limited to assessing the upper limbs and is a good predictor of morbidity and mortality, indicating that the HGD is a potentially useful instrument for evaluating different populations with different respiratory conditions. Despite these advantages, HGS is rarely used as a functional measure in patients with respiratory diseases, perhaps because it is erroneously considered a part of a complex battery of functional tests.
Current evidence indicates the presence of different phenomena linking lower muscle mass and function with the occurrence of CLDs in this population. Chronic systemic inflammation is related to nontransmissible CLDs in the elderly, and this inflammatory status may be one of the main links to reduced HGS. In addition to systemic inflammation, other contributors that appear to be important are the chronic effects of hypoxemia due to CLDs, physical inactivity, respiratory and peripheral myopathy, malnutrition, and the use of corticosteroids, which is common in many CLDs. Sarcopenic obesity is increasingly diagnosed in different clinical conditions and may be an important link between decreased HGS and adiposity in CLDs. Reduced HGS in CLDs should be considered a systemic phenomenon requiring a holistic approach to restore physical reconditioning and nutritional status. Therefore, early targeted interventions should be developed in patients with CLDs to delay muscle strength decline and prevent functional limitations and disabilities.