# Effect of Acute Dietary Nitrate Supplementation on the Changes in Calf Venous Volume during Postural Change and Skeletal Muscle Pump Activity in Healthy Young Adults

## TL;DR

This study found that drinking beetroot juice boosts nitric oxide activity but does not affect blood pooling or muscle pump action in the calf during posture changes.

## Contribution

The study demonstrates that acute dietary nitrate supplementation increases plasma nitrate but does not alter venous volume changes during postural shifts or muscle activity.

## Key findings

- Plasma nitrate concentration was higher after beetroot juice consumption compared to the control.
- Calf venous volume changes during posture shifts and tiptoe maneuvers were not significantly different between the groups.
- Acute nitrate supplementation does not affect venous pooling or skeletal muscle pump activity in healthy young adults.

## Abstract

Dietary nitrate (NO3−) supplementation is known to enhance nitric oxide (NO) activity and acts as a vasodilator. In this randomized crossover study, we investigated the effect of inorganic NO3− supplementation on the changes in calf venous volume during postural change and subsequent skeletal muscle pump activity. Fifteen healthy young adults were assigned to receive beetroot juice (BRJ) or a NO3−-depleted control beverage (prune juice: CON). Two hours after beverage consumption, the changes in the right calf volume during postural change from supine to upright and a subsequent right tiptoe maneuver were measured using venous occlusion plethysmography. The increase in calf volume from the supine to upright position (total venous volume [VV]) and the decrease in calf volume during the right tiptoe maneuver (venous ejection volume [Ve]) were calculated. Plasma NO3− concentration was higher in the BRJ group than in the CON group 2 h after beverage intake (p < 0.05). However, VV and Ve did not differ between CON and BRJ. These results suggest that acute intake of BRJ may enhance NO activity via the NO3− → nitrite → NO pathway but does not change calf venous pooling due to a postural change or the calf venous return due to skeletal muscle pump activity in healthy young adults.