Background and objective: Dietary nitrate supplementation through beetroot juice (BRJ) ingestion elicits acute ergogenic benefits for resistance training potentially due to increased skeletal muscle blood flow. However, it is unknown whether chronic BRJ supplementation alters resistance training-induced angiogenesis adaptations in middle-aged and older individuals. Therefore, we sought to determine whether 12 weeks of dietary nitrate supplementation combined with resistance training can enhance skeletal muscle angiogenesis and myofiber cross-sectional area compared with resistance training alone, in this population. Methods: 28 apparently healthy, untrained men and women (56±7 years old, 29.1±5.3 kg/m 2 body mass index) completed 12 weeks of supervised full-body resistance training (2x/week) while ingesting either BRJ (140 mL daily, providing 800 mg dietary nitrate; n=14 with 7 men/7 women) or nitrate-depleted BRJ placebo (PLA; n=14 with 7 men /7 women). Participants underwent a biopsy of the right mid-thigh vastus lateralis approximately 2-3 days before (PRE) and after (POST) 12 weeks of full-body resistance training. Biopsy analyses included a nitrate/nitrite (NOx) fluorometric assay, immunoblotting for proteins involved in angiogenesis, and immunohistochemistry to quantify fiber type-specific capillaries and cross-sectional areas (CSA). All outcome variables were analyzed using two-way mixed ANOVA (supplement group × time) with repeated measures on the time factor. Data are presented as means ± standard deviations, and statistical significance was set at p< 0.05 throughout. Results: Muscle NOx values did not significantly change following the intervention: +15.4% in BRJ (p=0.073) and +7.8% (p=0.514) in PLA. A paradoxical reduction in Type I myofiber CSA (p=0.017) from PRE to POST, and a significant increase in TSP-1 protein expression (p=0.031) from PRE to POST were observed. No significant group × time interactions were observed for the protein expression of VEGF, VEGFR2, TFEB, or eNOS/phospho-eNOS. Additionally, no significant group × time interactions were observed for Type IIa/x myofiber CSA. Conclusion: Dietary nitrate supplementation through BRJ over 12 weeks does not enhance resistance training-induced skeletal muscle angiogenesis adaptations in this cohort of middle-aged and older adults. These results signify that although there are acute benefits of BRJ supplementation for resistance training, they may not translate to chronic resistance-training induced adaptations in this demographic. Disclosure of funding sources: MCM was supported by the Porter Fellowship (American Physiological Society). Funding for most direct costs for this project was provided by a REAP Grant awarded to DTB and MDR by the Edward Via College of Osteopathic Medicine. This abstract was presented at the American Physiology Summit 2026 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.
McIntosh et al. (2026) studied this question.