Limb composition: implications for the determination of arterial occlusion pressure

Background: Blood flow restriction (BFR) training involves exercising under partial vascular occlusion to induce muscular adaptations, and the accurate determination of arterial occlusion pressure (AOP) is essential for its safe and effective prescription. Although limb size and blood pressure are established determinants of AOP, the role of lower-limb tissue composition and the influence of body position and sex on these relationships remain poorly understood. Purpose: This study aimed to examine the association between lower-limb body composition and lower-limb AOP measured using an 18-cm cuff across different body positions, while also exploring the influence of sex. Methods: Fifty-one healthy adults (25 men, 26 women) participated in this cross-sectional study. Whole-body and lower-limb composition were assessed using dual-energy X-ray absorptiometry (DXA). AOP was measured at the right thigh using a portable Doppler ultrasound in supine, seated, and standing positions. Associations were examined using bivariate correlations, multiple regression models adjusted for sex, commonality analyses (LMG metric), and linear mixed models for interactions. Results: In the seated position, fat mass was positively associated with AOP (β = 3.55; 95% CI: 0.15 to 6.96; p = 0.041), whereas lean mass was not. In the standing position, both lean mass (β = 2.96; 95% CI: 1.10 to 4.82; p = 0.002) and fat mass (β = 3.44; 95% CI: 0.48 to 6.40; p = 0.023) were positively associated with AOP. A significant lean mass × position interaction indicated weaker associations in the seated (β = -1.61; p < 0.001) and supine (β = -1.90; p < 0.001) positions compared with standing, while a significant fat mass × position interaction was observed only between the seated and supine positions (β = -2.45; p = 0.031). No significant sex-related interactions were detected. Conclusion: These findings indicate that lower-limb composition, especially lean and fat mass, is associated with AOP in a position-dependent manner, suggesting that tissue characteristics may be considered when estimating occlusion pressure using indirect methods.