Abstract
Introduction: Passive leg movement (PLM) is a non-invasive examination of vascular endothelial function that reflects nitric oxide vasodilation. Capsaicin activates transient receptor potential vanilloid 1 (TRPV1) channels, which has effects on vascular responses. While sex differences in vascular function have been well established, it is unclear whether males and females respond differently to capsaicin during PLM. Purpose: The purpose of this study was to investigate whether there was a sex difference in PLM measurements and their response to dietary capsaicin. Methods: Healthy young adults (n=66, 27 Male, 39 Female) were recruited and screened for eligibility, and participants completed experimental testing in a fasted and resting state. PLM was performed using repeated knee extension (90–180°, 1 Hz) while femoral artery blood flow was measured using Doppler ultrasound. Baseline PLM measurements were taken, and after 6 weeks of daily dietary capsaicin (n=34, 13 male, 21 female, 880mg capsaicin) or placebo (n=32, 14 male, 18 female, 800mg psyllium husk), same measurements were repeated. Results: There was no significant interaction for blood flow area under the curve (AUC) between treatment and time, with placebo (226±213 vs. 180±154mL, pre vs. post) and capsaicin (227±163 vs. 226±204mL, pre vs. post). There was a significant effect of sex between men and women (255±201 vs. 158±124mL, p=0.026). There was no significant interaction of sex and treatment in delta AUC in males (-27.9±221.5 and +36.0±314.0mL, placebo and capsaicin, respectively), as well as for females (-61.4±151.9 and -30.1±232.6mL for placebo and capsaicin, respectively). Conclusion: We found a significant sex difference in AUC, which could be explained by body size and vascular responsiveness. However, there was no sex specific effects in treatment. While many of our results were inconclusive, future studies may find greater insights with longer or increased dosing.
Recommended Citation
Collet, James
(2026)
"Sex Differences in Passive Leg Movement With Dietary Capsaicin: A Randomized Controlled Trial,"
International Journal of Exercise Science: Conference Proceedings: Vol. 15:
Iss.
9, Article 2.
Available at:
https://digitalcommons.wku.edu/ijesab/vol15/iss9/2