How Hand Grip Strength, Body Composition May Influence Health of Patients With OSA

Among patients with obstructive sleep apnea (OSA), reduced dominant hand grip strength (HGS) was found to correlate with lower oxygen nadir and increased apnea duration, with fat mass also consistently associated with worsening OSA indices, according to study findings published in Nature and Science of Sleep.

In prior studies, reduced HGS has been associated with increased severity of chronic conditions, with some reports finding it may also predict mortality. While assessed in chronic conditions such as cardiometabolic disease, researchers note that little is known of the association between HGS and OSA, which itself is linked with a range of cardiometabolic diseases, including hypertension and type 2 diabetes. Moreover, they say that these prior studies have not examined or adjusted for muscle mass.

“As HGS is an important indicator of chronic disease severity, but has been scarcely studied in OSA, this study examined associations between polysomnography (PSG)-derived OSA indices with HGS, muscle mass, and fat mass,” wrote the study authors.

Researchers derived data from the population-based Men, Androgen, Inflammation, Lifestyle, Environment and Stress (MAILES) cohort study (n = 613; age range = 41–88; body mass index = 28.6 ± 4.3), in which participants underwent in-home overnight PSG, assessment of dominant and nondominant HGS, and dual x-ray absorptiometry to determine whole body muscle mass and fat mass.

Linear models were then utilized to determine cross-sectional associations of PSG-derived OSA indices with HGS, muscle mass, and fat mass, with several lifestyle attributes adjusted for in the analysis:

• income, smoking status, diet, self-reported physical activity
• blood sample derived testosterone and systemic inflammation (C-reactive protein)
• cardiometabolic health
• depression

After adjusting for these variables, findings exhibited associations between reduced dominant HGS and lower oxygen nadir (unstandardized beta (β) = 0.19; 95% CI, 0.08 to 0.29), greater time spent below 90% oxygen saturation (β = −0.08; 95% CI, −0.14 to −0.02), and increased apnea duration (β = −0.3; 95% CI, −0.23 to −0.02). Conversely, there were no associations between HGS and the current standard used to determine severity of sleep apnea, the apnea-hypopnea index (AHI), as well as the REM AHI.

Additionally, muscle mass demonstrated no association with any OSA index, whereas fat mass was consistently associated with worsening OSA indices.

In a statement, lead study author David Stevens, PhD, research fellow at the Adelaide Institute for Sleep Health, highlighted that regardless of muscle mass, findings represent a distinct association for reduced HGS with worsening hypoxemia and increased apnea duration.

"This is important as up until now, age related declines in strength and immobility (sarcopenia) were thought to be due to reductions in muscle which started when someone was over 60 years old,” said Stevens. “Instead, the declines in strength appear to begin at a younger age in people with OSA."

Stevens noted that future research will further explore the relationship between OSA, body composition, and HGS.

Reference

Stevens D, Appleton S, Vincent AD, et al. Associations of OSA and nocturnal hypoxemia with strength and body composition in community dwelling middle aged and older men. Nat Sci Sleep. Published online November 10, 2020. doi:10.2147/NSS.S276932