Table 3.
Summary of studies investigating the effect of nitrates on strength performance.
| Study | Subjects | Design | Intervention | Performance Tests | Main Findings |
|---|---|---|---|---|---|
| Bender et al. (2018) [94] | 12 healthy, active male adolescents (16.8 ± 1.0 y; 74.8 ± 12.5 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (800 mg/~12.9 mmol nitrates) vs. nitrate depleted placebo; 150 min prior | IMTP 4 20 s WAnT |
↑ IMTP peak force ↔ WAnT |
| Coggan et al. (2015) [93] | 12 healthy men and women (36 ± 10 y; 26.1 ± 4.1 kg·m2) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (11.2 mmol nitrates) vs. nitrate depleted placebo; 120 min prior | Isokinetic knee extensions at 0, 90, 180, 270, & 360° s−1 50-contraction fatigue test at 180° s−1 |
↑ maximal knee extensor velocity ↑ maximal knee power velocity ↑ peak torque at 360° s−1 ↔ 50-contraction fatigue test |
| Flanagan et al. (2016) [104] | 14 resistance-trained males (21.1 ± 0.9 y; 77.6 ± 4.3 kg) | Randomized, double-blind, placebo-controlled, crossover study | Nitrate-rich bar (35.2 mg nitrates) vs. nitrate-poor bar; 3 days | Dynamic box squat pyramid protocol (60-90% 1RM ascending and descending load by 10%) Box squat MVIC with EMG |
↔ box squat repetitions to failure ↑ mean peak EMG amplitude |
| Garnacho-Castaño et al. (2022) [103] | 11 trained male CrossFit athletes (29.2 ± 3.7 y; 78.9 ± 5.4 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (~800 mg/12.8 mmol nitrates) vs. placebo; 180 min prior | 90 s of wall-balls (10 kg) and 60 s of back squat (50% 1RM) separated by 3 min rest, followed by 90 s of wall-balls (10 kg) and 60 s of back squat (50% 1RM) without rest between the two exercises | ↑ back squat repetitions completed in 1st round ↔ wall-balls repetitions completed in 1st round ↔ back squat or wall-balls completed in 2nd round |
| Haynes et al. (2021) [86] | 10 resistance-trained males (22.6 ± 3.2 y; 88.3 ± 7.8 kg) | Randomized, double-blind, placebo-controlled, crossover study | Red spinach extract (180 mg nitrates) vs. maltodextrin placebo; 7 days (60 min prior) | 5 sets of bench press (75% 1RM) to failure | ↔ repetitions to failure ↔ velocity & power during bench press |
| Haider & Folland (2014) [97] | 19 healthy untrained males (21 ± 3 y; 73 ± 10 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (9.7 mmol) vs. placebo; 7 days (150 min prior) | Surface EMG during voluntary and involuntary knee extension MVIC at 110° & 120° | ↔ maximal and explosive voluntary force ↑ maximal evoked force ↑ twitch peak force |
| Jonvik et al. (2021) [96] | 15 recreationally active males (25 ± 4 y; 81 ± 10 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (985 mg nitrates) vs. nitrate depleted placebo; 6 days (180 min prior) | CMJ Knee extension MVIC at 30° & 60° Isokinetic knee extension/flexion at 60°,120°,180°, & 300°·s−1 30 isokinetic knee extensions at 180°·s−1 |
↔ CMJ jump ↔ isometric strength ↑ isokinetic knee flexion power at 60°·s−1 ↔ isokinetic knee flexion power at 120°,180°, and 300°·s−1 ↔ isokinetic knee extension power at all velocities ↔ total workload and fatigue index for 30 isokinetic repetitions |
| Jurado-Castro et al. (2022) [101] | 14 physically active women (25.4 ± 4.0 y; 57.0 ± 5.4 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (400 mg/6.4 mmol nitrates) vs. nitrate depleted placebo; 120 min prior | CMJ Back squat mean and peak power and velocity at 50% and 70% 1RM 3 sets of back squat, leg press, and leg extension (75% 1RM) to failure |
↑ CMJ height ↑ mean/peak velocity at 50% 1RM ↑ mean/peak power at 50% 1RM ↑ repetitions to failure |
| Kramer et al. (2016) [95] | 12 male CrossFit athletes (23 ± 5 y; 82.7 ± 13.5 kg) | Randomized, double-blind, placebo-controlled, crossover study | 8 mmol potassium nitrate vs. nitrate-free potassium chloride; 6 days | Day 1: 2 sets of 5 isokinetic knee extension/flexion at 60°·s−1 and 180°·s−1 30-s WAnT Day 2: CrossFit workout (“Grace” protocol) |
↔ Isokinetic leg performance ↔ Isometric leg performance ↑ peak WAnT power ↔ CrossFit performance |
| Mosher et al. (2016) [98] | 12 recreationally trained males (21 ± 2 y; 82.5 ± 9.8 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (6.4 mmol nitrate) vs. nitrate depleted placebo; 6 days (150 min prior) | 3 sets of bench press (60% 1RM) to failure | ↑ repetitions to failure ↑ total weight lifted |
| Porcelli et al. (2016) [81] | 7 recreationally active males (25 ± 2 y; 66.3 ± 6.0 kg) | Randomized, crossover study | High-nitrate diet (~8.2 mmol·d−1) vs. control diet (~2.9 mmol·d−1); 6 days | Knee extension MVIC Isometric knee extensions (75% max voluntary torque) to failure |
↔ MVIC ↑ muscle work during isometric knee extensions |
| Ranchal-Sanchez et al. (2020) [99] | 12 recreationally trained males (24 ± 3 y; 73 ± 9.2 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (400 mg nitrates) vs. nitrate depleted placebo; 120 min prior | 3 sets of the back squat and bench press (60%, 70%, and 80% 1RM) to failure | ↑ total repetitions to failure ↑ back squat repetitions to failure ↔ bench press repetitions to failure ↔ maximum power & velocity for back squat and bench press |
| Rodríguez-Fernández et al. (2021) [102] | 18 healthy, active adult males (22.8 ± 4.9 y; 74.4 ± 9.6 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (800 mg nitrates) vs. nitrate depleted placebo; 150 min prior | 4 sets of 8 maximal half-squats on flywheel device at inertial loads of 0.025, 0.050, 0.075, & 0.100 kg·m−2 | ↑ mean/peak power during concentric and eccentric contractions at all inertial loads |
| Tan et al. (2022) [87] | 14 recreationally active males (22 ± 5 y; 84 ± 17 kg) | Randomized, double-blind, placebo-controlled, cross-over study | BRJ (11.8 mmol nitrates) vs. nitrate depleted placebo; 4 days | 2 sets of 2 “explosive” back squat and bench press repetitions (70% 1RM) 1 set of back squat and bench press (60% 1RM) to failure |
↔ back squat mean/peak power ↔ bench press mean/peak power ↑ bench press repetitions to failure ↔ quadricep & pectoralis tissue saturation index |
| Tillin et al. (2018) [113] | 17 recreationally active males (23 ± 4 y; 74.0 ± 9.6 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (800 mg/~12.9 mmol nitrate) vs. nitrate depleted placebo; 7 days (150 min prior) | Knee extensions MVIC and involuntary tetanic contractions at 10, 20, 50, and 100 Hz in unfatigued and fatigued state (following 60 MVICs) | ↔ knee extension performance in unfatigued state ↓ fatigue during the 60 MVICs ↑ knee extension performance in fatigued state (lower decline in tetanic force) |
| Townsend et al. (2021) [105] | 16 Division I male baseball athletes (20.5 ± 1.7 y; 90.4 ± 10.5 kg) | Randomized, double-blind, placebo-controlled, parallel study | Red spinach extract (180 mg nitrates) vs. placebo; daily for 11 weeks during offseason training (~30 min prior) | 1RM bench press 30 s WAnT Body composition Muscle thickness of RF and VL via ultrasound |
↔ 1RM Bench Press ↔ WAnT ↔ Body Composition ↔ Muscle Thickness (RF, VL) |
| Trexler et al. (2019) [58] | 27 recreationally active males (22.0 ± 4.0 y; 78.9 ± 12.5 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (400 mg nitrates) vs. placebo; 120 min prior | 5 sets of 30 maximal isokinetic concentric knee extensions at 180°·s−1 | ↔ peak and average torque ↔ total work ↔ blood lactate ↔ femoral artery diameter ↔ vastus lateralis cross-sectional area |
| Williams et al. (2020) [100] | 11 resistance-trained males (22.1 ± 2.4 y; 89.3 ± 10.3 kg) | Randomized, double-blind, placebo-controlled, crossover study | BRJ (400 mg nitrate) vs. nitrate depleted placebo; 120 min prior | 2 sets of 2 “explosive” bench press repetitions (70% 1RM) 3 sets of bench press (70% 1RM) to failure |
↑ mean power & velocity ↑ repetitions to failure |
↑ = significantly greater (p < 0.05) than placebo; ↓ = significantly less (p < 0.05) than placebo; ↔ = no significant difference between supplement and placebo; 1RM = one-repetition maximum; BRJ = beetroot juice; CMJ = countermovement jump; EMG = electromyography; IMTP = isometric mid-thigh pull; MVIC = maximal voluntary isometric contraction; RF = rectus femoris; VL = vastus lateralis; WAnT = Wingate anaerobic test.