Abstract
Objectives: We examined the acute effects of anthocyanin-rich New Zealand blackcurrant extract and a placebo on hemodynamics during 120 min of sedentary sitting in healthy males. Additionally, we investigated whether changes in resting hemodynamics altered repeated isometric hand-grip exercise performance and post exercise forearm blood flow (FBF).Methods: Ten healthy males completed two trials during which they ingested either blackcurrant extract (1.87 mg total anthocyanins/kg bodyweight) or placebo powder. Heart rate, blood pressure and forearm blood flow were measured, and venous blood was sampled, prior to and 30, 60, 90 and 120 min-post ingestion. Participants remained seated for the duration of each trial. At 120 min post-ingestion participants completed as many repetitions of isometric hand-grip contractions as possible.Results: Heart rate, blood pressure and mean arterial pressure changed over time (all p < 0.001) but did not differ between treatments. A treatment x time interaction for FBF (p = 0.025) and forearm vascular resistance (FVR) (p = 0.002) was found. No difference in the number of isometric hand-grip contractions was observed between treatments (p = 0.68) nor was there any treatment x time interaction in post-exercise FBF (p = 0.997). Plasma endothelin-1 (p = 0.023) and nitrate (p = 0.047) changed over time but did not differ between treatments (both p > 0.1). Plasma nitrite did not change over time (p = 0.732) or differ between treatments (p = 0.373).Conclusion: This study demonstrated that acute ingestion of a single dose of blackcurrant extract maintained FBF and FVR during an extended period of sitting; however, this did not influence exercise performance during hand-grip exercise.
Highlights
Sitting in an upright position for extended periods leads to significant changes in hemodynamics [1,2,3], as a result of blood pooling in the lower extremities and reduced venous return [4]
The total anthocyanin composition of the blackcurrant powder was determined by high performance liquid chromatography (HPLC) using procedures described by Lyall et al [26]
Mean arterial pressure (MAP) and Total peripheral resistance (TPR) significantly increased over the 120 min period at rest (p = 0.001 and 0.0001, respectively) (Figures 1C,D)
Summary
Sitting in an upright position for extended periods leads to significant changes in hemodynamics [1,2,3], as a result of blood pooling in the lower extremities and reduced venous return [4]. Studies demonstrating the benefits of consuming berryfruit on cardiovascular health have ascribed these benefits to their high phytochemical and anthocyanin content [6, 7] These compounds are reported to influence vascular tone through their ability to regulate mechanisms that mediate nitric oxide bioavailability [8, 9] and endothelin-1 expression [10]. Blackcurrants (Ribes nigrum L.) contain a range of different anthocyanins [11] and have been demonstrated to modulate resting forearm blood flow [12] and other hemodynamic variables [13] in healthy males The size of these effects were dose dependent and coincided with the bioavailability of anthocyanins and their metabolites
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