Background: We examined the acute effect of a red spinach extract (RSE) (1000 mg dose; ~90 mg nitrate (NO
)) on performance markers during graded exercise testing (GXT).
Methods: For this randomized, double-blind, placebo (PBO)-controlled, crossover study, 15 recreationally-active participants (aged
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Background: We examined the acute effect of a red spinach extract (RSE) (1000 mg dose; ~90 mg nitrate (NO
)) on performance markers during graded exercise testing (GXT).
Methods: For this randomized, double-blind, placebo (PBO)-controlled, crossover study, 15 recreationally-active participants (aged 23.1 ± 3.3 years; BMI: 27.2 ± 3.7 kg/m
2) reported >2 h post-prandial and performed GXT 65–75 min post-RSE or PBO ingestion. Blood samples were collected at baseline (BL), pre-GXT (65–75 min post-ingestion; PRE), and immediately post-GXT (POST). GXT commenced with continuous analysis of expired gases.
Results: Plasma concentrations of NO
increased PRE (+447 ± 294%;
p < 0.001) and POST (+378 ± 179%;
p < 0.001) GXT with RSE, but not with PBO (+3 ± 26%, −8 ± 24%, respectively;
p > 0.05). No effect on circulating nitrite (NO
) was observed with RSE (+3.3 ± 7.5%, +7.7 ± 11.8% PRE and POST, respectively;
p > 0.05) or PBO (−0.5 ± 7.9%, −0.2 ± 8.1% PRE and POST, respectively;
p > 0.05). When compared to PBO, there was a moderate effect of RSE on plasma NO
at PRE (g = 0.50 [−0.26, 1.24] and POST g = 0.71 [−0.05, 1.48]). During GXT, VO
2 at the ventilatory threshold was significantly higher with RSE compared to PBO (+6.1 ± 7.3%;
p < 0.05), though time-to-exhaustion (−4.0 ± 7.7%;
p > 0.05) and maximal aerobic power (i.e., VO
2 peak; −0.8 ± 5.6%;
p > 0.05) were non-significantly lower with RSE.
Conclusions: RSE as a nutritional supplement may elicit an ergogenic response by delaying the ventilatory threshold.
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