Effects of Dietary Nitrate and Caffeine on End Power and Work Above End Power During a 3 min All-Out Test in Trained Male Cyclists.

2026-05-02
Nutrients 18(9)
- Anthony M Hagele
- Kyle L Sunderland
- Petey W Mumford
- Chad M Kerksick

PubMed: 42124064
DOI: 10.3390/nu18091463

Study Design

Type: Randomized Controlled Trial (RCT)
Population: Fifteen healthy, trained male cyclists (28.5 ± 5.3 years, 79.2 ± 9.1 kg, VO2peak 55.2 ± 5.6 mL·kg-1·min-1)
Methods: Randomized, double-blind, placebo-controlled, crossover study design; four conditions: placebo beverage + placebo capsule, nitrate-rich beetroot juice + placebo capsule, placebo beverage + caffeine capsule, nitrate-rich beetroot juice + caffeine capsule; nitrate-rich beetroot juice (~13 mmol NO3-) or nitrate-depleted placebo three hours before exercise, caffeine (5 mg∙kg-1) or maltodextrin placebo one hour before testing; 3 min all-out test on a cycle ergometer
Blinding: Double-blind
Duration: 3 hours before exercise and 1 hour before testing (acute supplementation)
Funding: Unclear

Rigorous Journal

Background

The purpose of this study was to examine the effects of acute dietary nitrate (NO₃^-) and caffeine (CAF) supplementation on end power (EP) and work performed above EP (WEP) in trained male cyclists during a 3 min all-out test (3MT) on a cycle ergometer.

Methods

Fifteen healthy, trained male cyclists (28.5 ± 5.3 years, 79.2 ± 9.1 kg, VO₂peak 55.2 ± 5.6 mL·kg^-1·min^-1) completed four exercise trials in a randomized, double-blind, placebo-controlled, crossover study design separated by 3-7 days. The four experimental conditions were placebo beverage (nitrate-depleted) + placebo capsule, nitrate-rich beetroot juice + placebo capsule (BR), placebo beverage + caffeine capsule (CAF), and nitrate-rich beetroot juice + caffeine capsule (BR + CAF). Participants consumed nitrate-rich beetroot juice (~13 mmol NO₃^-) or nitrate-depleted placebo three hours before exercise, and caffeine (5 mg∙kg^-1) or maltodextrin placebo one hour before testing. EP and WEP were determined from the 3MT. Secondary outcomes included peak and mean power output. Data were analyzed using a repeated-measures ANOVA with repeated measures on condition. A p-value of 0.05 was used to determine statistical significance. Effect size was evaluated using partial eta squared.

Results

No significant effect of condition was observed for EP (p = 0.401, ηp² = 0.056), WEP (p = 0.580, ηp² = 0.048), peak power (p = 0.642, ηp² = 0.046), mean power (p = 0.212, ηp² = 0.108), or total work (p = 0.217, ηp² = 0.107).

Conclusions

No statistically significant differences between conditions were detected under the conditions of the present study.

Research Insights

Beetroot→Improved Endurance Power
No significant effect of condition was observed for EP (p = 0.401, ηp2 = 0.056)
Effect
Neutral
Effect size
Small
Dose
~13 mmol NO3-
Beetroot→Improved Mean Power
No significant effect of condition was observed for mean power (p = 0.212, ηp2 = 0.108)
Effect
Neutral
Effect size
Small
Dose
~13 mmol NO3-
Beetroot→Improved Peak Power
No significant effect of condition was observed for peak power (p = 0.642, ηp2 = 0.046)
Effect
Neutral
Effect size
Small
Dose
~13 mmol NO3-
Beetroot→Improved Work Above End Power
No significant effect of condition was observed for WEP (p = 0.580, ηp2 = 0.048)
Effect
Neutral
Effect size
Small
Dose
~13 mmol NO3-
Beetroot→Improved Work Capacity
No significant effect of condition was observed for total work (p = 0.217, ηp2 = 0.107)
Effect
Neutral
Effect size
Small
Dose
~13 mmol NO3-