Effects of short-term and prolonged supplementation of beetroot juice on cardiovascular and cognitive function and mood of healthy older compared to younger adults

Beetroot intervention: One bottle (250ml) of nitrate-rich beetroot juice (10.5 mmol nitrate) consumed once daily for 28 days. Intervention adherence will be controlled for by having participants return all empty bottle to the head researcher who will double-check labelling and number. In total participants will complete 5 trials: a familiarisation trial, a cycle trial, and three supplementation trials. The familiarisation and cycle trial will occur within two weeks of each other and at least 2 days apart to ensure they are still familiar with tests and that they are not still fatigue from the familiarisation trial. The cycle trial and first supplementation trial will be separated by one week and the 3 supplementation trials will occur on day 1, 14 and 28 of supplementation. The familiarisation trial will be used to familiarise the participant with the procedures and equipment, and an incremental cycle test will be completed at the end to work out their work rate max and set the amount of work required for them to complete in the cycle test for the next 4 trials (this is based on 75% of their max for 20min). During the cycle trial baseline measures of blood pressure, heart rate, systemic vascular resistance and mean arterial pressure (USCOM 1A) cognitive function, cerebral near-infrared spectroscopy, perceptual and mood tests were completed (Noted somewhere practice measure how to state). This was followed by the exercise test which was a work done time trial on the cycle (complete a predetermined work as fast as possible). For the supplementation trials, prior to consumption of the beverage, baseline measures will be completed as above followed by a collection of a resting blood sample. Participants then consumed the allocated drink with breakfast and remain in the laboratory for a 2.25 h absorption period. After 2.25 h, the aforementioned measurements were repeated prior to commencing the exercise protocol which will be that same cycle as the in the cycle trial. Following the completion of the cycle test baseline measures of blood pressure, heart rate, perceptual and mood tests, and blood sample were repeated.