Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation.
We tested the hypothesis that dietary nitrate (NO3-)-rich beetroot juice (BR) supplementation could partially offset deteriorations in O2transport and utilization and exercise tolerance after blood donation. Twenty-two healthy volunteers performed moderate-intensity and ramp incremental cycle exercise tests prior to and following withdrawal of ∼450 ml of whole blood. Before donation, all subjects consumed seven 70-ml shots of NO3--depleted BR [placebo (PL)] in the 48 h preceding the exercise tests. During the 48 h after blood donation, subjects consumed seven shots of BR (each containing 6.2 mmol of NO3-, n = 11) or PL (n = 11) before repeating the exercise tests. Hemoglobin concentration and hematocrit were reduced by ∼8-9% following blood donation (P < 0.05), with no difference between the BR and PL groups. Steady-state O2uptake during moderate-intensity exercise was ∼4% lower after than before donation in the BR group (P < 0.05) but was unchanged in the PL group. The ramp test peak power decreased from predonation (341 ± 70 and 331 ± 68 W in PL and BR, respectively) to postdonation (324 ± 69 and 322 ± 66 W in PL and BR, respectively) in both groups (P < 0.05). However, the decrement in performance was significantly less in the BR than PL group (2.7% vs. 5.0%, P < 0.05). NO3-supplementation reduced the O2cost of moderate-intensity exercise and attenuated the decline in ramp incremental exercise performance following blood donation. These results have implications for improving functional capacity following blood loss.
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom; and.
Sinead T J
ST
McDonagh
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom; and.
Anni
A
Vanhatalo
University of Exeter Medical School, St. Luke's Campus, University of Exeter, Exeter, United Kingdom.
Jonathan
J
Fulford
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom; and.
Lee J
LJ
Wylie
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom; and.
Stephen J
SJ
Bailey
Sport and Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter, United Kingdom; and a.m.jones@exeter.ac.uk.
Andrew M
AM
Jones
D000328:Adult; D027461:Beta vulgaris; D001782:Blood Donors; D019587:Dietary Supplements; D004311:Double-Blind Method; D005080:Exercise Test; D017079:Exercise Tolerance / Q000187:drug effects*; D005260:Female; D000067030:Fruit and Vegetable Juices; D064368:Healthy Volunteers; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D009566:Nitrates / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects*; D055815:Young Adult
D006454:Hemoglobins; D009566:Nitrates
O2 transport; O2 uptake; beetroot juice; blood withdrawal; exercise performance; nitric oxide