Influence of acute beetroot juice supplementation on cold-induced vasodilation and fingertip rewarming

Purpose Vasoactive ingredients in beetroot (BR) such as nitrate are known to induce vasodilation in temperate conditions. This study investigated the effect of BR ingestion on cold induced vasodilation (CIVD) and rewarming of finger skin temperature (T-fing) during and after hand immersion in cold water. Methods Twenty healthy males (mean +/- SD; age 22.2 +/- 0.7 years, height 172.6 +/- 6.0 cm, body mass 61.3 +/- 11.7 kg) repeated a hand cold water immersion test twice with prior BR or water beverage ingestion (randomised order). They rested for 2 h in thermoneutral conditions (27 degrees C, 40% relative humidity) after consuming the beverage, then immersed their non-dominant hand in 8 degrees C water for 30 min. They then rewarmed their hand in the ambient air for 20 min. Skin temperature at seven body sites, T-fing, finger skin blood flow (SkBF(fing)), and blood pressure were measured. Results During hand immersion parameters of CIVD (T-fing and SkBF(fing)) were not different between BR and water conditions although skin temperature gradient from proximal to distal body sites was significantly smaller with BR (P < 0.05). During rewarming, SkBF(fing) and cutaneous vascular conductance were significantly higher with BR than with water (P < 0.05). The rewarming speed in T-fing and SkBF(fing) was significantly faster with BR at 15- (BR 1.24 +/- 0.22 vs water 1.11 +/- 0.26 degrees C/min) and 20-min rewarming (P < 0.05). Additionally, individuals with slower rewarming speed with water demonstrated accelerated rewarming with BR supplementation. Conclusion BR accelerated rewarming in T-fing and SkBF(fing) after local cold stimulus, whereas, CIVD response during hand cold immersion was not affected by BR ingestion.