Introduction: Most studies investigating the effects of NO3 supplementation were performed during the supplementation period. The aim of the present study was to look for after effects of such a supplementation and answer the question: are there influences on the development of performance? Methods: 17 subjects took part in the placebo-controlled double-blind study (Nitrate: 9; Placebo (NaCl) 8). Maximum power in a preceding incremental test was not significantly different between the groups (N: 4.83 +/- 0.9Watt/kg, PLA: 4.85 +/- 0.6 Watt/kg). The subjects performed an intermittent training of high intensity (HIIT) on a cycle ergometer (Lode Excalibur) 3 times a week for 3 weeks (45x 30s at 100% - 10W and 30s of 10W, 45). The subjects supplemented either sodium-nitrate [8.5 mg/kg body weigh/d] (N, n=9) or sodium-chloride [8.5 mg/kg body weight/d] (PLA n=8) daily. Besides the incremental test (IT) a double Wingate-Test (one minute break between both, (WT)) and an endurance test to exhaustion (ET) with 80% of maximum power reached in the incremental test were performed as pre- and post-tests. [NO3] and [NO2] were measured in the cubital venous plasma (GC-MS-Method, Tsikas et al. 2000). The post-tests were performed at least 2 days after the end of supplementation period, when [NO3] and [NO2] in plasma are supposed to have returned to normal values (Webb et al. 2008). Results: [NO3] and [NO2] did not differ between the pre- tests and the tests performed 2 days after supplementation (S). At least 2 days after the supplementation period (S) in the first WT maximal power (+4.5%) and mean power (+4.2%) were increased in PLA (p<0.05 for both) whereas there was no significant difference in N. Both groups improved maximal (+9%) and mean power (+7%) in the second WT (p<0.05 for all) without any difference between the groups. However, the oxygen cost per Watt was significantly (p<0.05) reduced in N (-11.5%). During the ET (4 days after S) the VO2 was significantly lower. Even at exhaustion there was a 5% reduction in VO2 (p<0.01). In spite of that the endurance time was not significantly different. Maximum Power reached in the IT post-test was enhanced in both groups (+3.9% in PLA) and (+5.1% in N) being significant in N, only. Again, the increase in VO2/Watt was lower in N (p<0.05). Conclusion: A supplementation of NO3 for 3 weeks elicits effects on performance lasting at least for 7 days. The persisting effects look similar to those expected when fast muscle fibers change to more oxidative fibers.
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