Table 3.
Summary of studies reviewed examining the effects of nitrate supplementation on trained athletes of cyclic endurance performance.
| Reference | Participants | Age | Sports Experience and/or Training Load | VO2max (mL/kg/min) | Supplementation Protocol | Nitrate Dose (mmol/day) | Last Dose (hours) | Exercise Protocol | Principal Performance Measures | Results |
|---|---|---|---|---|---|---|---|---|---|---|
| Balsalobre et al. [22] | M, middle and long-distance runners (n = 12) | 26.3 ± 5.1 | International athletes with personal bests | 71.8 ± 5.2 | BJ 70 mL (15 days) | 6.5 | 24 | Incremental running test to exhaustion | Time (s), RPE, SmO2 (%), VO2 (mL/kg/min) | Time (S: 1269 ± 53.6 vs. PLA: 1230 ± 73.5, D = yes), RPE (S: 6 ± 1 vs. PLA: 7.7 ± 1, D = yes), SmO2 (S: 31 ± 6.9 vs. PLA: 27.7 ± 4.8, D = yes), VO2 (S: 69.5 ± 2.9 vs. PLA: 71.4 ± 4.8, D = no) |
| Bescós et al. [18] | M, cyclists and triathletes (n = 13) | 32.6 ± 5.6 | Experience in endurance events: 8 ± 5 years, training volume: 15.7 ± 5.0 h/wk |
60 ± 7 | Sodium nitrate 250 mL (3 days) | 11.6 | 3 | Distance trial (40 min) in cycle ergometer | Distance covered (km), Mean power output (W), VO2 (mL/kg/min) | Distance covered (S: 26.4 ± 1.1 vs. PLA: 26.3 ± 1.2, D = no), mean power output (S: 258 ± 28 vs. PLA: 257 ± 28, D = no), VO2 (S: 51 ± 7.9 vs. PLA: 50.9 ± 6.6, D = no) |
| Bescós et al. [23] | M, cyclists and triathletes (n = 11) | 34.3 ± 4.8 | Members of competitive squads | 65.1 ± 6.2 | Sodium nitrate 250 mL (1 day) | 11.8 | 3 | Submaximal cycling trial (4 × 6 min) (T1), incremental exercise test to exhaustion (T2) | T1: VO2 (L/min) at 3.5 W/kg T2: time (s), maximal power (W), VO2peak (L/min) |
T1: VO2 (S: 0.5 ± 0.11 vs. 0.53 ± 0.06, D = no) T2: time (S: 416 ± 32 vs. PLA: 409 ± 27, D = no), maximal power (S: 416 ± 29 vs. PLA: 410 ± 28, D = no), VO2peak (S: 4.64 ± 0.35 vs. PLA: 4.82 ± 0.33, D = yes) |
| Boorsma et al. [24] | M, distance runners (n = 8) | 23.8 ± 5 | Elite distance; experience: provincial, national, or international events; training volume: 12.3 ± 4 h/wk |
80 ± 5 | BJ 210 mL (1 day) | 19.5 | 1.5 | Submaximal treadmill run (T1), time trial 1500 m (T2) | T1: VO2 (mL/min) T2: time (s) | T1: VO2 (S: 4192 ± 113 vs. PLA: 4194 ± 90, D = no) T2: time (S: 250 ± 7 vs. PLA: 250 ± 4, D = no) |
| BJ 210 mL (on the test day) and 140 (other days) (8 days) | 19.5 and 13 | 2.5 | Submaximal treadmill run (T1), time trial 1500 m (T2) | T1: VO2 (mL/min) T2: time (s) | T1: VO2 (S: 4299 ± 92 vs. PLA: 4216 ± 95, D = no) T2: time (S: 250 ± 5 vs. PLA: 251 ± 4, D = no) |
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| Callahan et al. [25] | M, cyclists (n = 8) | 34 ± 7 | Well-trained cyclist | 65.2 ± 4.2 | Beetroot crystals 15 g (3 days) | 5 | 1 | Time trial 4 km | Mean power output (W), time (s) | Mean power output (S: 388 ± 54 vs. PLA: 386 ± 56, D = no), time (S: 337.4 ± 17.1 vs. PLA: 338.1 ± 18, D = no) |
| Cermak et al. [26] | M, cyclists and triathletes (n = 12) | 31 ± 3 | Training history of ≈10 years, training volume: ≈10 h/wk. |
58 ± 2 | BJ 140 mL (6 days) | 8 | 2.5 | Submaximal cycling trail (2 × 30 min) (P1), time trial 10 km (T2) | T1: VO2 (L/min) T2: mean power output (W), Time (s) |
T1: VO2 (S: 2.94 ± 0.1 vs. PLA: 3.1 ± 0.09, D = yes) T2: mean power output (S: 294 ± 41.5 vs. PLA: 288 ± 41.5, D = yes), time (S: 953 ± 72.5 vs. PLA: 965 ± 72.5, D = yes) |
| Cermak et al. [27] | M, cyclists and triathletes (n = 20) | 26 ± 1 | Training experience: >3 times/wk for several years | 60 ± 1 | BJ 140 mL (1 day) | 8.7 | 2.5 | Time trial ≈1 h | Mean power output (W), time (min) | Mean power output (S: 275 ± 7 vs. PLA: 278 ± 7, D = no), time (S: 65.5 ± 1.1 vs. PLA: 65 ± 1.1, D = no) |
| Christensen et al. [28] | M, cyclists (n = 10) | 29 ± 4 | Experience: elite cyclists competing at the highest domestic level | 72.1 ± 4.5 | BJ 500 mL (6 days) | 8 | 3 | Submaximal cycling trial at 70% Wmax (2 × 6 min) (T1), repeated sprint test (6 × 20 s) (T2), time trial 400 kcal (≈20 min) (T3) | T1: VO2 (mL/min) T2: mean power output (W) T3: mean power output (W), time (min) |
P1: VO2 (S: 792 ± 82 vs. PLA: 806 ± 82, D = no) P2: mean power output (S: 630 ± 84 vs. PLA: 630 ± 92, D = no) P3: mean power output (S: 290 ± 43 vs. PLA: 285 ± 44, D = no), time (S: 18.20 vs. PLA: 18.37, D = no) |
| Esen et al. [29] | M (n = 5) and F (n = 5), swimmers (n = 10) | 22 ± 6 | Experience: ≥10 years competing at club standard and ≥5 years competing in regional and university-level. Training volume: 3–4 times/wk and 6–8 h/wk |
2212 | BJ 140 mL (3 days) | 8 | 3 | Time trial 200 m (T1), time trial 100 m (T2) |
T1: time (s) T2: time (s) |
T1: time (S: 152.6 ± 14.1 vs. PLA: 152.5 ± 14.1, D = no) T2: time (S: 69.5 ± 7.2 vs. PLA: 69.4 ± 7.4, D = no) |
| Garnacho et al. [30] | M, triathletes (n = 12) | 39.3 ± 7.5 | Experience: National (n = 8) and international (n = 4) level of competition; training volume: ≥4 times/wk with ≥1 h/session | 54.8 ± 3.1 | BJ 70 mL (1 day) | 6.5 | 3 | Time trial at VT1 (30 min) and VT2 (15 min) | VO2 (L/min), VCO2 (L/min), time (s) at VT2 | VO2 (S: 73.8 ± 8.9 vs. PLA: 72.2 ± 9.4, D = no), VCO2 (S: 3.1 ± 0.3 vs. PLA: 2.9 ± 0.4, D = yes), time VT2 (S: 933 vs. PLA: 882, D = no) |
| Glaister et al. [31] | F, cyclists and triathletes (n = 14) | 31 ± 7 | Experience: ≈13 years actively in sport; training volume: 10.7 ± 2.2 h/wk at the time of the investigation | 52.3 ± 4.9 | BJ 70 mL (1 day) | 7.3 | 2.5 | Time trial 20 km | Time (min) | Time (S: 35.33 ± 1.5 vs. PLA: 35.37 ± 1.7, D = no) |
| Hoon et al. [32] |
M, cyclists (n = 26) | 20.3 ± 1.4 | Trained male cyclists that were involved in a 6 week training camp at the Australian Institute of Sport | - | BJ 70 mL (1 day) | 4.1 | 1.25 | Time trail 4 min ×2 | Mean power output (W) | Mean power output (S: 403 ± 52 vs. PLA: 396 ± 57, D = no) |
| 2.5 | Time trail 4 min ×2 | Mean power output (W) | Mean power output (S: 402 ± 47 vs. PLA: 396 ± 57, D = no) | |||||||
| Hoon et al. [33] | M, rowers (n = 10) | 20.6 ± 2.5 | Highly trained; 2000-m personal-best time: 6 min, 17 s ± 10 s; training volume: 16.9 ± 3.4 h/wk | - | BJ 70 mL (1 day) | 4.2 | 2 | Time trial 2000 m | Time (s) | Time (S: 383.4 ± 8.7 vs. PLA: 3835 ± 9, D = no) |
| BJ 140 mL (1 day) | 8.4 | 2 | Time trial 2000 m | Time (s) | Time (S: 381.9 ± 9 vs. PLA: 383.5 ± 9, D = yes) | |||||
| Lane et al. [34] | M (n = 12) and F (n = 12), cyclists and triathletes (n = 24) | 31 ± 7 | Competitive level | 71.6 ± 4.6 | BJ 140 mL (1 day) | 8.4 | 2 | Time trial 43.83 km | Time (min), power output (W) | Time (S: 64 ± 2.8 vs. PLA: 63.5 ± 3.2, D = no), power output (S:298 ± 35 vs. PLA: 303 ± 41, D = no) |
| 28 ± 6 | Competitive level | 59.9 ± 5.1 | BJ 140 mL (1 day) | 8.4 | 2 | Time trial 29.35 km | Time (min), power output (W) | Time (p > 0.05), power output (S: 207 ± 31 vs. PLA: 207 ± 29, D = no) | ||
| Lansley et al. [35] | M, cyclists (n = 9) | 21 ± 4 | Competitive level | 56 ± 5.7 | BJ 500 mL (1 day) | 6.2 | 2.5 | Time trial 4 km | Time (min), mean power output (W), VO2 (L/min) | Time (S: 6.27 ± 0.35 vs. PLA: 6.45 ± 0.42, D = yes), mean power output (S: 292 ± 44 vs. PLA: 279 ± 51, D = yes), VO2 (S: 4.46 ± 0.5 vs. PLA: 4.36 ± 0.47, D = no) |
| Time trial 16.1 km | Time (min), mean power output (W), VO2 (L/min) | Time (S: 26.9 ± 1.8 vs. PLA: 27.7 ± 2.1, D = yes), mean power output (S: 247 ± 44 vs. PLA: 233 ± 43, D = yes), VO2 (S: 4.32 ± 0.47 vs. PLA: 4.19 ± 0.56, D = no) | ||||||||
| Lowings et al. [36] | M (n = 5) and F (n = 5), swimmers (n = 10) | 20 ± 1 | Competitive level; training volume: ≥3 times/wk | − | BJ 140 mL (1 day) | 12.5 | 3 | Time trial 168 m | Time (s) | Time (p = 0.144), nitric oxide bioavailability + |
| MacLeod et al. [37] | M, cyclists (n = 11) | 29.3 ± 5.1 | Trained cyclists that met the inclusion criterion VO2peak > 5 L/min | 67.5 ± 5.8 | BJ 70 mL (1 day) | 6.5 | 2 | Time trial 15 km | Time (s), mean power output (W/kg) | Time (S: 961 ± 54 vs. PLA: 954 ± 47, D = no), mean power output (S: 3.7 ± 0.4 vs. PLA: 3.8 ± 0.3, D = no) |
| McQuillan et al. [38] | M, cyclists (n = 9) | 27 ± 9 | Endurance trained cyclists and competing in cycle races in the 3 months preceding the study; training volume: regular 11.4 ± 2.6 hr/wk and 310.27 km/wk | 68 ± 3 | BJ 140 mL (3 days) | 8 | 2.5 | Time trial 4 km | Time (s), mean power output (W) | Time (S: 341 ± 12 vs. PLA: 340 ± 10, D = no), mean power output (S: 390 ± 45 vs. PLA: 393 ± 37, D = no) |
| BJ 140 mL (4 days) | 8 | 2.5 | Time trial 1 km | Time (s), mean power output (W) | Time (S: 79.6 ± 3.5 vs. PLA: 79.2 ± 2.9, D = no), mean power output (S: 8495 ± 61 vs. PLA: 503 ± 51, D = no) | |||||
| BJ 140 mL (6 days) | 8 | 2.5 | Time trial 4 km | Time (s), mean power output (W) | Time (S: 340 ± 10 vs. PLA: 340 ± 11, D = no), mean power output (S: 394 ± 38 vs. PLA: 393 ± 37, D = no) | |||||
| BJ 140 mL (7 days) | 8 | 2.5 | Time trial 1 km | Time (s), mean power output (W) | Time (S: 79.3 ± 3.3 vs. PLA: 79 ± 3, D = no), mean power output (S: 501 ± 59 vs. PLA: 505 ± 52, D = no) | |||||
| McQuillan et al. [39] | M, cyclists (n = 8) | 26 ± 8 | Well-trained endurance cyclists; training volume: weekly training duration 9 ± 3 h/wk |
63 ± 4 | BJ 70 mL (8 days) | 4 | 2 | Time trial 4 km | Time (s), mean power output (W) | Time (S: 343.6 ± 14.3 vs. PLA: 344.8 ± 14, D = no), mean power output (S: 380 ± 41 vs. PLA: 375 ± 40, D = no) |
| Nyakayiru et al. [40] | M, cyclists and triathletes (n = 17) | 25 ± 4 | Competitive cyclist; experience: 9.6 ± 5.1 years; training volume: 9.7 ± 3.7 h/wk |
65 ± 4 | Sodium nitrate 1097 mg (1 day) | 12.9 | 4 | Submaximal cycling trial at 45% Wmax (30 min) and 65% Wmax (30 min) (T1), time trial 10km (T2), | T1: VO2 T2: time (s) |
T1: VO2 (D = no) T2: time (S: 1022 ± 72 vs. PLA: 1017 ± 71, D = no) |
| Sodium nitrate 1097 mg (6 days) | 12.9 | 4 | submaximal cycling trial at 45% Wmax (30 min) and 65% Wmax (30min) (T1), time trial 10km (T2) | T1: VO2 T2: time (s) |
T1: VO2 (D = no) T2: time (S: 1004 ± 61 vs. PLA: 1017 ± 71, D = no) |
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| Nybäck et al. [41] | M (n = 5) and F (n = 3), cross-country skiers (n = 8) | 21.8 ± 2.8 | Well-trained, competing at a national level | 71.5 ± 4.7 (M) | BJ 140 mL (1 day) | 13 | 2.5 | Submaximal test (2 × 6 min) (T1), time trial 1 km (T2) | T1: VO2 (L/min) T2: time (s) | T1: VO2 (S: 2.92 ± 0.48 vs. PLA: 2.9 ± 0.49, D = no) T2: time (S: 297 ± 29 vs. PLA: 295 ± 29, D = no) |
| Pawlak et al. [13] | M, triathletes and runners (n = 9) | 21.7 ± 3.7 | Runners from clubs engaged in intense endurance exercise training and competition; inclusion based on VO2max > 65 mL/kg/min | 71.1 ± 5.2 | BJ 500 mL (3 days) | 5.4 | 3 | Repeated sprint test to exhaustion | No. of sprints completed, mean power output (W), VO2 (mL/min) | No. of sprints completed (S: 13.9 ± 4 vs. PLA: 14.2 ± 4.5, D = no), mean power output (S: 579.2 ± 57.7 vs. PLA: 578.9 ± 54.3, D = no), VO2 (S: 3378.5 ± 681.8 vs. PLA: 3466.1 ± 505.3, D = no) |
| Peacock et al. [42] | M, cross-country skiers (n = 10) | 18 | Experience: national and international standard junior skiers, all among the 20 best in the 2010 Norwegian Cup Series; training history: 502 ± 45 h/year | 69.6 ± 5.1 | Potassium nitrate 1 g (1 day) |
9.9 | 2.5 | Submaximal test at 55% VO2max (5 min) and 75% VO2max (5 min) (T1), time trial 5 km (T2) | T1: VO2 (L/min) T2: time (s) |
T1: VO2 (S: 3.77 ± 0.62 vs. PLA: 3.89 ± 0.39, D = no) T2: time (S: 1005 ± 53 vs. PLA: 996 ± 49, D = no) |
| Pinna et al. [43] | M, swimmers (n = 14) | 34.7 ± 7.5 | Master athletes involved in regional and national competitions; training volume: average of 6.5 ± 0.8 h per week; training frequency ranged 3–4 times/wk, with 3000–5000 m distance covered each time | 42.7 ± 2.6 | BJ 500 mL (6 days) | 5.5 | 3 | Incremental swimming test | Workload (kg/min), VO2 (mL/min) | Workload (S: 6.7 ± 1.1 vs. PLA: 6.35 ± 1 D = yes), VO2 (S: 2741 ± 454 vs. PLA: 2817 ± 545, D = no) |
| Rokkedal et al. [44] | M, cyclists (n = 12) | 29.1 ± 7.7 | Well-trained in performance level 4 [47,48] | 66.4 ± 5.3 | BJ 140 mL (7 days) | 12.4 | 2.75 | Time trial 10 km | Power output (W), time (s), VO2 (mL/min) | Power output (S: 315.8 ± 13.2 vs. PLA: 311.3 ± 13.2, D = yes), time (S: 884,5 ± 16 vs. PLA: 890,1 ± 16, D = yes), VO2 (D = yes) |
| Shannon et al. [45] | M, runners and triathletes (n = 8) | 28.3 ± 5.8 | Experience in competing in running events | 62.3 ± 8.1 | BJ 140 mL (1 day) | 12.5 | 3 | Time trial 1500 m | Time (s), VO2 (mL/kg/min) | Time (S: 319.6 ± 36.2 vs. PLA: 325.7 ± 38.8, D = yes) VO2 (S: 53.4 ± 6.8 vs. PLA: 53.9 ± 6.9, D = no) |
| Time trial 10 km | Time (s), VO2 (mL/kg/min) | Time (S: 2643.1 ± 324,1 vs. PLA: 2649.9 ± 319.8, D = no), VO2 (S: 49 ± 6 vs. PLA: 48.6 ± 6.3, D = no) | ||||||||
| Wilkerson et al. [46] | M, cyclists (n = 8) | 31 ± 11 | Well-trained subjects; training volume: 5.8 ± 1.0 times per week and completed 11.1 ± 2.5 h training per week |
63 ± 8 | BJ 500 mL (1 day) | 6.2 | 2.5 | Time trial 50 miles | Time (min), mean power output (W) | Time (S: 136.7 ± 5.6 vs. PLA: 137.9 ± 6.4, D = no), mean power output (S: 238 ± 22 vs. PLA: 235 ± 27, D = no) |
M: male, F: female, VO2max: maximal oxygen uptake, VO2peak: peak oxygen uptake, BJ: beetroot juice, SmO2: vastus lateralis oxygen saturation, RPE: rating of perceived exertion, VCO2: expired carbon dioxide, D: statistical difference, T: trial, VT: ventilatory threshold, PLA: placebo, S: supplemented.