Background
Blackcurrant contains anthocyanin, a component known to induce vasorelaxation and vasodilation in rat aortic rings (Ziberna et al., 2013). In humans, blackcurrant intake has been reported to increase peripheral blood flow (Matsumoto et al., 2005), with higher anthocyanin intake having beneficial effects on cardiovascular function in women (Jennings et al., 2012). However, the effect of blackcurrant intake on cardiovascular function in endurance-trained athletes is unknown. We examined the effect of 1-week Sujon blackcurrant powder supplementation on resting cardiovascular function of trained triathletes.

Methods
Thirteen healthy triathletes with >3 years experience (8 men; mean±SD: age: 38±8 years, height: 174±5 cm, body mass: 71±9 kg, BMI: 23±2, BF%: 19±5%, VO2max: 49.1±6.2 mL∙kg-1∙min-1, maximum power: 305±68 W) volunteered. Participants were tested following 7 days of Sujon blackcurrant powder (S, 6g/day) or placebo (P) intake, administered following a double-blind, crossover, randomized design with a wash-out period of 4 weeks. Cardiovascular function was recorded for 20 min in supine participants using a beat-to-beat blood pressure monitoring system (Portapres® Model 2, Finapres Medical Systems BV, Amsterdam, The Netherlands). Cardiovascular measures were averaged over 10 consecutive beats, with the lowest systolic blood pressure (BP) and associated measures analysed. Paired two-tailed t-tests were used for analysis with significance accepted at p≤.05.

Results
There were no differences in systolic BP (P: 121±23, S: 120±23 mmHg, p=.92), diastolic BP (P: 69±16, S: 63±14 mmHg, p=.12), mean arterial BP (P: 86±18, S: 82±18 mmHg, p=.33), and heart rate (P: 58±9, S: 59±10 beats∙min-1, p=.95). Stroke volume (P: 82±23, S: 99±25 mL, p<.01) and cardiac output (P: 4.8±1.6, S: 5.8±1.7 L, p<.05) were increased by 25% and 26%, respectively. There was a 16% lower total peripheral resistance (P: 20.2±8.9, S: 15.2±5.3 mmHg∙L-1∙min-1, p=.05). The changes in resting cardiovascular function were observed in 10 participants.

Conclusions
Resting cardiovascular function of trained endurance athletes responds positively to 1-week intake of New Zealand Sujon blackcurrant powder. Intake of New Zealand Sujon blackcurrant powder is associated with 1) an increase in stroke volume and cardiac output, and 2) a decrease in total peripheral resistance. For resting skeletal muscles, these observations may influence the delivery of nutrients and clearance of metabolites. The effect on New Zealand Sujon blackcurrant on resting cardiovascular function may support the recovery of endurance athletes.

Acknowledgement
Funding for this study and conference attendance was provided by the University of Chichester, Health Currancy Ltd (UK) and Gibb Holdings (Nelson) Ltd (NZ).