Estimates of cardiorespiratory fitness are associated with carotid artery compliance: role of biological sex

Background: Lower estimates of cardiorespiratory fitness (eCRF) are associated with increased cardiovascular disease (CVD)-related and all-cause mortality. Decreased carotid artery compliance and associated changes in blood pressure are key processes contributing to increased CVD risk and are influenced by biological sex. Therefore, the current study sought to examine the relation between eCRF, carotid artery compliance and blood pressure and to explore the impact of biological sex on this relationship. Methods: Ninety-three (44M/49F, age 46±19 y, body mass index 27±5 kg/m2) adults underwent assessments of carotid artery compliance and blood pressure, lipid profile and body composition (e.g., dual x-ray absorptiometry and waist circumference). eCRF was determined via an established equation. Results: Compared to males, females had higher body fat percentage (39.8±7.0 vs 30.5±7.7 %, p<0.0001) and high-density lipoprotein cholesterol (63.1±13.1 vs 49.2±13.4 mg/dL, p<0.0001) and lower triglycerides (91.4±39.4 vs 124.8±70.0 mg/dL, p=0.006), lean mass (41.1±4.6 vs 55.4±8.7 mg/dL, p<0.0001), fat free-mass index (FFMI, 15.9±1.6 vs 18.9±2.3, p<0.0001), waist circumference (WC, 91.1±13.2 vs 97.0±14.1 cm, p=0.03) and eCRF (22.5 ± 7.0 vs 33.8 ± 4.9 mL•kg•min-1, p<0.0001). No differences were observed between males and females for carotid artery systolic blood pressure (cSBP, 114.0±17.9 vs 114.0±13.8 mmHg, p=0.98), diastolic blood pressure (cDBP, 73.0±8.3 vs 72.4±6.8 mmHg, p=0.69), pulse pressure (cPP, 41.0±15.0 vs 41.4±12.0 mmHg, p=0.86), β-stiffness (3.2±0.4 vs 3.1±0.3 AU, p=0.31), compliance (0.12±0.1 vs 0.13±0.1 mm2/mmHg, p=0.25), distensibility coefficient (0.004±0.002 vs 0.004±0.001 10-3/kPa, p=0.70), elastic modulus (17.2±9.0 vs 14.7±6.5 kPa, p=0.13) and carotid pulsatile stress (PS, 2,694.0±934.4 vs 2,680.0±915.7 mmHg/min, p=0.94). eCRF was associated with cSBP (r = -0.50), cDBP (r = -0.48), cPP (r = -0.33), carotid intima-media thickness, (cIMT, r = -0.51), β-stiffness (r = -0.33), distensibility coefficient (r = 0.34), elastic modulus (r = -0.29) and carotid PS (r = -0.47) (all, p<0.05) in females but not males. Due to baseline subject characteristics differences, we re-examined the relation between eCRF, and assessments of carotid artery compliance adjusted for WC+FFMI+triglycerides in a multivariable combined model. Notably, the relation between eCRF and carotid artery β-stiffness (r = -0.38), distensibility coefficient (r = 0.36), elastic modulus (r = -0.30) and carotid PS (r = -0.31) (all, p<0.05) remained after multivariable adjustment in females but not males suggesting the relationship between eCRF and carotid artery compliance in females is not due to measures of adiposity, fat-free mass or circulating triglycerides. Conclusion: These data provide novel insight into the influence of eCRF on carotid artery compliance in a sex-dependent manner. Further, the notion that maintaining CRF may provide lower CVD risk in females through enhanced carotid artery compliance supports the importance of evaluating sex as a biological variable in cardiovascular research. This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.