Discrete physiological effects of beetroot juice and potassium nitrate supplementation following 4-wk sprint interval training

The physiological and exercise performance adaptations to sprint interval training (SIT) may be modified by dietary nitrate ([Formula: see text]) supplementation. However, it is possible that different types of [Formula: see text] supplementation evoke divergent physiological and performance adaptations to SIT. The purpose of this study was to compare the effects of 4-wk SIT with and without concurrent dietary [Formula: see text] supplementation administered as either [Formula: see text]-rich beetroot juice (BR) or potassium [Formula: see text] (KNO3). Thirty recreationally active subjects completed a battery of exercise tests before and after a 4-wk intervention in which they were allocated to one of three groups: 1) SIT undertaken without dietary [Formula: see text] supplementation (SIT); 2) SIT accompanied by concurrent BR supplementation (SIT + BR); or 3) SIT accompanied by concurrent KNO3 supplementation (SIT + KNO3). During severe-intensity exercise, V̇o2peak and time to task failure were improved to a greater extent with SIT + BR than SIT and SIT + KNO3 ( P < 0.05). There was also a greater reduction in the accumulation of muscle lactate at 3 min of severe-intensity exercise in SIT + BR compared with SIT + KNO3 ( P < 0.05). Plasma [Formula: see text] concentration fell to a greater extent during severe-intensity exercise in SIT + BR compared with SIT and SIT + KNO3 ( P < 0.05). There were no differences between groups in the reduction in the muscle phosphocreatine recovery time constant from pre- to postintervention ( P > 0.05). These findings indicate that 4-wk SIT with concurrent BR supplementation results in greater exercise capacity adaptations compared with SIT alone and SIT with concurrent KNO3 supplementation. This may be the result of greater NO-mediated signaling in SIT + BR compared with SIT + KNO3. NEW & NOTEWORTHY We compared the influence of different forms of dietary nitrate supplementation on the physiological and performance adaptations to sprint interval training (SIT). Compared with SIT alone, supplementation with nitrate-rich beetroot juice, but not potassium [Formula: see text], enhanced some physiological adaptations to training.

Download Full-text

Influence of dietary nitrate supplementation on physiological and muscle metabolic adaptations to sprint interval training

Journal of Applied Physiology ◽

10.1152/japplphysiol.00909.2016 ◽

2017 ◽

Vol 122 (3) ◽

pp. 642-652 ◽

Cited By ~ 24

Author(s):

Christopher Thompson ◽

Lee J. Wylie ◽

Jamie R. Blackwell ◽

Jonathan Fulford ◽

Matthew I. Black ◽

...

Keyword(s):

Exercise Performance ◽

Interval Training ◽

Moderate Intensity ◽

Sprint Interval Training ◽

Beetroot Juice ◽

Dietary Nitrate ◽

Metabolic Adaptations ◽

Physiological Adaptations ◽

Severe Intensity ◽

Nitrate Supplementation

We hypothesized that 4 wk of dietary nitrate supplementation would enhance exercise performance and muscle metabolic adaptations to sprint interval training (SIT). Thirty-six recreationally active subjects, matched on key variables at baseline, completed a series of exercise tests before and following a 4-wk period in which they were allocated to one of the following groups: 1) SIT and [Formula: see text]-depleted beetroot juice as a placebo (SIT+PL); 2) SIT and [Formula: see text]-rich beetroot juice (~13 mmol [Formula: see text]/day; SIT+BR); or 3) no training and [Formula: see text]-rich beetroot juice (NT+BR). During moderate-intensity exercise, pulmonary oxygen uptake was reduced by 4% following 4 wk of SIT+BR and NT+BR ( P < 0.05) but not SIT+PL. The peak work rate attained during incremental exercise increased more in SIT+BR than in SIT+PL ( P < 0.05) or NT+BR ( P < 0.001). The reduction in muscle and blood [lactate] and the increase in muscle pH from preintervention to postintervention were greater at 3 min of severe-intensity exercise in SIT+BR compared with SIT+PL and NT+BR ( P < 0.05). However, the change in severe-intensity exercise performance was not different between SIT+BR and SIT+PL ( P > 0.05). The relative proportion of type IIx muscle fibers in the vastus lateralis muscle was reduced in SIT+BR only ( P < 0.05). These findings suggest that BR supplementation may enhance some aspects of the physiological adaptations to SIT. NEW & NOTEWORTHY We investigated the influence of nitrate-rich and nitrate-depleted beetroot juice on the muscle metabolic and physiological adaptations to 4 wk of sprint interval training. Compared with placebo, dietary nitrate supplementation reduced the O2 cost of submaximal exercise, resulted in greater improvement in incremental (but not severe-intensity) exercise performance, and augmented some muscle metabolic adaptations to training. Nitrate supplementation may facilitate some of the physiological responses to sprint interval training.

Download Full-text

Dietary nitrate supplementation attenuates the reduction in exercise tolerance following blood donation

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00451.2016 ◽

2016 ◽

Vol 311 (6) ◽

pp. H1520-H1529 ◽

Cited By ~ 5

Author(s):

Sinead T. J. McDonagh ◽

Anni Vanhatalo ◽

Jonathan Fulford ◽

Lee J. Wylie ◽

Stephen J. Bailey ◽

...

Keyword(s):

Exercise Tolerance ◽

Peak Power ◽

Blood Donation ◽

Hemoglobin Concentration ◽

Moderate Intensity ◽

Beetroot Juice ◽

Moderate Intensity Exercise ◽

Exercise Tests ◽

Dietary Nitrate ◽

Nitrate Supplementation

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.

Download Full-text

The Effect of Dietary Nitrate Supplementation on Physiology and Performance in Trained Cyclists

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.2016-0202 ◽

2017 ◽

Vol 12 (5) ◽

pp. 684-689 ◽

Cited By ~ 9

Author(s):

Joseph A. McQuillan ◽

Deborah K. Dulson ◽

Paul B. Laursen ◽

Andrew E. Kilding

Keyword(s):

Time Trial ◽

Crossover Design ◽

Moderate Intensity ◽

Beetroot Juice ◽

Double Blind ◽

Dietary Nitrate ◽

Performance Time ◽

Exercise Economy ◽

Nitrate Supplementation ◽

And Performance

Purpose:To determine the effect of dietary nitrate (NO3 –) supplementation on physiology and performance in well-trained cyclists after 6–8 d of NO3 – supplementation.Methods:Eight competitive male cyclists (mean ± SD age 26 ± 8 y, body mass 76.7 ± 6.9 kg, VO2peak 63 ± 4 mL · kg–1 · min–1) participated in a double-blind, placebo-controlled, crossover-design study in which participants ingested 70 mL of beetroot juice containing ~4 mmol NO3 – (NIT) or a NO3 –-depleted placebo (PLA), each for 8 d. Replicating pretreatment measures, participants undertook an incremental ramp assessment to determine VO2peak and first (VT1) and second (VT2) ventilatory thresholds on d 6 (NIT6 and PLA6), moderate-intensity cycling economy on d 7 (NIT7 and PLA7), and a 4-km time trial (TT) on d 8 (NIT8 and PLA8).Results:Relative to PLA, 6 d of NIT supplementation produced unclear effects for VO2peak (mean ± 95% confidence limit: 1.8% ± 5.5%) and VT1 (3.7% ± 12.3%) and trivial effects for both VT2 (–1.0% ± 3.0%) and exercise economy on d 7 (–1.0% ± 1.6%). However, effects for TT performance time (–0.7% ± 0.9%) and power (2.4% ± 2.5%) on d 8 were likely beneficial.Conclusions:Despite mostly unclear outcomes for standard physiological determinants of performance, 8 d of NO3 – supplementation resulted in likely beneficial improvements to 4-km TT performance in well-trained male endurance cyclists.

Download Full-text

Dietary nitrate supplementation: effects on plasma nitrite and pulmonary O2 uptake dynamics during exercise in hypoxia and normoxia

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.00068.2014 ◽

2014 ◽

Vol 307 (7) ◽

pp. R920-R930 ◽

Cited By ~ 66

Author(s):

James Kelly ◽

Anni Vanhatalo ◽

Stephen J. Bailey ◽

Lee J. Wylie ◽

Christopher Tucker ◽

...

Keyword(s):

Exercise Tolerance ◽

Moderate Intensity ◽

Beetroot Juice ◽

Moderate Intensity Exercise ◽

Exercise Tests ◽

Double Blind ◽

Dietary Nitrate ◽

Severe Intensity ◽

Rate Of Decline ◽

Plasma Nitrite

We investigated the effects of dietary nitrate (NO3−) supplementation on the concentration of plasma nitrite ([NO2−]), oxygen uptake (V̇o2) kinetics, and exercise tolerance in normoxia (N) and hypoxia (H). In a double-blind, crossover study, 12 healthy subjects completed cycle exercise tests, twice in N (20.9% O2) and twice in H (13.1% O2). Subjects ingested either 140 ml/day of NO3−-rich beetroot juice (8.4 mmol NO3; BR) or NO3−-depleted beetroot juice (PL) for 3 days prior to moderate-intensity and severe-intensity exercise tests in H and N. Preexercise plasma [NO2−] was significantly elevated in H-BR and N-BR compared with H-PL ( P < 0.01) and N-PL ( P < 0.01). The rate of decline in plasma [NO2−] was greater during severe-intensity exercise in H-BR [−30 ± 22 nM/min, 95% confidence interval (CI); −44, −16] compared with H-PL (−7 ± 10 nM/min, 95% CI; −13, −1; P < 0.01) and in N-BR (−26 ± 19 nM/min, 95% CI; −38, −14) compared with N-PL (−1 ± 6 nM/min, 95% CI; −5, 2; P < 0.01). During moderate-intensity exercise, steady-state pulmonary V̇o2 was lower in H-BR (1.91 ± 0.28 l/min, 95% CI; 1.77, 2.13) compared with H-PL (2.05 ± 0.25 l/min, 95% CI; 1.93, 2.26; P = 0.02), and V̇o2 kinetics was faster in H-BR (τ: 24 ± 13 s, 95% CI; 15, 32) compared with H-PL (31 ± 11 s, 95% CI; 23, 38; P = 0.04). NO3− supplementation had no significant effect on V̇o2 kinetics during severe-intensity exercise in hypoxia, or during moderate-intensity or severe-intensity exercise in normoxia. Tolerance to severe-intensity exercise was improved by NO3− in hypoxia (H-PL: 197 ± 28; 95% CI; 173, 220 vs. H-BR: 214 ± 43 s, 95% CI; 177, 249; P = 0.04) but not normoxia. The metabolism of NO2− during exercise is altered by NO3− supplementation, exercise, and to a lesser extent, hypoxia. In hypoxia, NO3− supplementation enhances V̇o2 kinetics during moderate-intensity exercise and improves severe-intensity exercise tolerance. These findings may have important implications for individuals exercising at altitude.

Download Full-text

The effects of dietary nitrate supplementation on the adaptations to sprint interval training in previously untrained males

Journal of Science and Medicine in Sport ◽

10.1016/j.jsams.2016.04.014 ◽

2017 ◽

Vol 20 (1) ◽

pp. 92-97 ◽

Cited By ~ 14

Author(s):

David J. Muggeridge ◽

Nicholas Sculthorpe ◽

Philip E. James ◽

Chris Easton

Keyword(s):

Interval Training ◽

Sprint Interval Training ◽

Dietary Nitrate ◽

Nitrate Supplementation

Download Full-text

Dietary Nitrate Supplementation and 3-weeks Sprint Interval Training Improves Flow Mediated Dilation in Healthy Males

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000485775.36248.31 ◽

2016 ◽

Vol 48 ◽

pp. 257

Author(s):

David J. Muggeridge ◽

Nicholas Sculthorpe ◽

Philip E. James ◽

Chris Easton

Keyword(s):

Interval Training ◽

Flow Mediated Dilation ◽

Sprint Interval Training ◽

Dietary Nitrate ◽

Nitrate Supplementation ◽

Healthy Males

Download Full-text

Acute beetroot juice supplementation on sympathetic nerve activity: a randomized, double-blind, placebo-controlled proof-of-concept study

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00163.2017 ◽

2017 ◽

Vol 313 (1) ◽

pp. H59-H65 ◽

Cited By ~ 28

Author(s):

Karambir Notay ◽

Anthony V. Incognito ◽

Philip J. Millar

Keyword(s):

Nitric Oxide ◽

Blood Pressure ◽

Sympathetic Outflow ◽

Beetroot Juice ◽

Proof Of Concept ◽

Burst Frequency ◽

Double Blind ◽

Dietary Nitrate ◽

Nitrate Supplementation ◽

Central Sympathetic Outflow

Acute dietary nitrate ([Formula: see text]) supplementation reduces resting blood pressure in healthy normotensives. This response has been attributed to increased nitric oxide bioavailability and peripheral vasodilation, although nitric oxide also tonically inhibits central sympathetic outflow. We hypothesized that acute dietary [Formula: see text] supplementation using beetroot (BR) juice would reduce blood pressure and muscle sympathetic nerve activity (MSNA) at rest and during exercise. Fourteen participants (7 men and 7 women, age: 25 ± 10 yr) underwent blood pressure and MSNA measurements before and after (165–180 min) ingestion of 70ml high-[Formula: see text] (~6.4 mmol [Formula: see text]) BR or [Formula: see text]-depleted BR placebo (PL; ~0.0055 mmol [Formula: see text]) in a double-blind, randomized, crossover design. Blood pressure and MSNA were also collected during 2 min of static handgrip (30% maximal voluntary contraction). The changes in resting MSNA burst frequency (−3 ± 5 vs. 3 ± 4 bursts/min, P = 0.001) and burst incidence (−4 ± 7 vs. 4 ± 5 bursts/100 heart beats, P = 0.002) were lower after BR versus PL, whereas systolic blood pressure (−1 ± 5 vs. 2 ± 5 mmHg, P = 0.30) and diastolic blood pressure (4 ± 5 vs. 5 ± 7 mmHg, P = 0.68) as well as spontaneous arterial sympathetic baroreflex sensitivity ( P = 0.95) were not different. During static handgrip, the change in MSNA burst incidence (1 ± 8 vs. 8 ± 9 bursts/100 heart beats, P = 0.04) was lower after BR versus PL, whereas MSNA burst frequency (6 ± 6 vs. 11 ± 10 bursts/min, P = 0.11) as well as systolic blood pressure (11 ± 7 vs. 12 ± 8 mmHg, P = 0.94) and diastolic blood pressure (11 ± 4 vs. 11 ± 4 mmHg, P = 0.60) were not different. Collectively, these data provide proof of principle that acute BR supplementation can decrease central sympathetic outflow at rest and during exercise. Dietary [Formula: see text] supplementation may represent a novel intervention to target exaggerated sympathetic outflow in clinical populations. NEW & NOTEWORTHY The hemodynamic benefits of dietary nitrate supplementation have been attributed to nitric oxide-mediated peripheral vasodilation. Here, we provide proof of concept that acute dietary nitrate supplementation using beetroot juice can decrease muscle sympathetic outflow at rest and during exercise in a normotensive population. These results have applications for targeting central sympathetic overactivation in disease.

Download Full-text