Obesity remains one of the biggest health challenges worldwide. Sarcopenia, a progressive loss of muscle strength, is associated with a higher risk of disability and lower quality of life. Both conditions can occur independently of each other; however, share a common inflammatory pathway, leading to serious health problems. Previous studies have shown a positive association between severe sarcopenia and respiratory disease incidence/mortality, however, it is unclear if this association is modified by obesity. The aim of this work, therefore, was to investigate the association of severe sarcopenia and severe sarcopenic-obesity with respiratory incidence and mortality in the UK Biobank cohort.

242,572 white participants from the UK biobank study were included. Severe sarcopenia was defined as the combination of low muscle mass, low grip strength and slow gait speed. Severe sarcopenic-obesity was defined, using 3 different criteria. The combination of severe sarcopenia plus at least one of the following criteria: BMI ≥ 30 kg/m2, waist circumference (WC) > 88 cm in women and > 102 cm in men, or the two highest quintiles of body fat (60%). Associations between severe sarcopenic and severe sarcopenic-obesity and respiratory incidence and mortality were investigated using Cox-proportional hazard models.

In people without sarcopenia, high BMI, WC and body fat were associated with a reduced risk of respiratory disease mortality (HR: 0.70 [0.52; 0.85], HR: 0.74 [95%CI: 062: 088] and HR: 0.74 [95%CI: 0.63; 0.88], respectively). In comparison to people without sarcopenia or obesity, those with severe sarcopenia had three times higher risk of respiratory disease incidence (HR: 3.13 [95%CI: 2.25; 4.35]) and five times higher risk of mortality (HR: 5.37 [95%CI: 2.96: 9.74]). However, sarcopenic-obesity, based on WC and body fat, was only associated with a moderately increased respiratory disease incidence (HR 1.60 [95%CI: 1.04; 2.46] and HR: 1.52 [1.04: 2.22], respectively). There were no associations between respiratory mortality and sarcopenic-obesity.

Higher levels of adiposity may be a protective factor against respiratory mortality and could reduce the effect of severe sarcopenia over this disease. However, the mechanism behind this association needs to elucidate.