Acute whole body UVA irradiation combined with nitrate ingestion enhances time trial performance in trained cyclists

Abstract

Dietary nitrate supplementation has been shown to increase nitric oxide (NO) metabolites, reduce blood pressure (BP) and enhance exercise performance. Acute exposure to ultraviolet (UV)-A light also increases NO bioavailability and reduces BP. We conducted a randomized, counterbalanced placebo-controlled trial to determine the effects of UV-A light alone and in combination with nitrate on the responses to sub-maximal steady-state exercise and time trial (TT) performance. Nine cyclists (VO2max 53.1 ± 4.4 ml/kg/min) completed five performance trials comprising 10 min submaximal steady-state cycling followed by a 16.1 km TT. s; d=0.28) compared to PLA + SHAM. These findings demonstrate that exposure to UV-A light alone does not alter the physiological responses to exercise or improve performance a laboratory setting. A combination of UV-A and NIT, however, does improve cycling TT performance in this environment which may be due to a larger increase in NO availability.

Nitrate pharmacokinetics: Taking note of the difference

“…With a burgeoning awareness of the potential importance of NO 3 -in sport and exercise, an ever-increasing variety of NO 3 -fortified products are becoming commercialised, ranging from sport bars and lozenges to BR capsules. Importantly, NO 3 -salts (in solution or via capsule) are readily available for both oral and intravenous administration and ] ratio, as defined in Table 1) was relatively consistent (1.0-1.2) and is in keeping with the work of most using BR [11][12][13][14], but inconsistent with Webb et al hrs, and a plasma t½ of >6 hrs is found irrespective of KNO 3 dose (4 -24 mmol).…”

“…Certainly in our hands [13] there remains noticeable variation in both time to peak, and peak plasma [ . It is tempting to speculate this reflects mainly differences in dealing with and/or storing the plasma sample as we and others have demonstrated [15].…”

“…Of those utilising a similar BR source, in one or two repeated tests there is an apparent split between those exhibiting high relative yield [12][13][14] and those finding significantly lower yield [3,11]. In these examples, volume of NO 3 -administration does not appear to be the cause of the discrepancy, neither does this appear to be methodological (since all studies essentially use ozonebased chemiluminescence to measure plasma NO metabolites). ]…”

“…Consistent with this, it appears that ambient O 2 influences the ability of NO 3 -ingestion to enhance exercise performance. In hypoxia, intramuscular perturbation of phosphate-linked substrates and metabolites is blunted when exercise is preceded by NO 3 -ingestion [26] and cycle time trial [13] and incremental exercise [27] performance in hypoxia is improved following NO 3 -supplementation. The recovery of muscle phosphocreatine concentration, an index of oxidative capacity, is enhanced in hypoxia but not normoxia following NO 3 -supplementation and this effect appears to be related to improved muscle oxygenation [28].…”

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

“…Despite these apparent acute benefits to supramaximal exercise resulting from dietary nitrate shown that NO metabolites appear to reach peak concentrations in the plasma faster when 258 ingesting the nitrate gels compared to beetroot juice (1-1.5 h and 2.5-3 h, respectively) 23 . It 259 remains to be determined whether these pharmacokinetic dissimilarities are due to individual 260 differences or the inherent characteristics of the supplements themselves.…”