Muscle Strength as a Key Independent Predictor of Arterial Stiffness and Metabolic Syndrome in Aging Mexicans: Unveiling the Sarcopenic Obesity Paradox

Background/Objectives: The cardiometabolic consequences of sarcopenic obesity (SO) remain poorly characterized in Latin America. We hypothesized that SO uniquely concentrates aortic stiffness, metabolic syndrome, and vitamin D deficiency in older Mexican adults, and that handgrip strength exhibits a dose–response relationship with cardiometabolic risk independent of adiposity. Methods: We conducted a cross-sectional analysis of 2087 adults ≥ 50 years from the Mexican Health and Aging Study (MHAS) 2012. Four phenotypes were defined using EWGSOP2 criteria: lean–fit, lean–sarcopenic, obese–non-sarcopenic, and obese–sarcopenic (BMI ≥ 30 kg/m2). Outcomes were pulse pressure (PP, aortic stiffness proxy), metabolic syndrome (modified IDF criteria), and serum 25(OH)D. Normality tests confirmed non-normal distribution (p < 0.001). Given heteroscedasticity (Breusch–Pagan p < 0.001), HC3 robust standard errors were used. Regression models were sex-adjusted and sex-stratified. Results: The sample showed high cardiometabolic burden: mean HbA1c 6.91% (35.3% ≥ 6.5%); metabolic syndrome 57.6%; mean PP 60.7 ± 17.9 mmHg; mean gait speed 0.708 m/s (70.4% slow). Phenotype distribution: lean–fit 12.3%; lean–sarcopenic 47.3%; obese–non-sarcopenic 8.7%; obese–sarcopenic 31.7%. In multivariable models, handgrip strength was an independent protective predictor of PP (beta = −0.09 per kg; 95% CI: −0.17 to −0.01; p = 0.033), with a sex-specific effect in women (beta = −0.13; p = 0.010). Conclusions: SO is highly prevalent in older Mexican adults and associates with an adverse cardiometabolic profile. Handgrip strength shows a protective dose–response association with cardiometabolic risk independent of adiposity, identifying muscle function as a candidate modifiable factor that warrants confirmation in longitudinal and interventional studies. The obese–non-sarcopenic phenotype exhibited the lowest PP, unveiling the sarcopenic obesity paradox: adiposity without muscle function loss does not promote arterial stiffening.