Blackcurrant Alters Physiological Responses and Femoral Artery Diameter During Sustained Isometric Contraction

Blackcurrant is rich in anthocyanins that may affect exercise-induced physiological
responses. We examined tissue oxygen saturation, muscle activity, cardiovascular responses and
femoral artery diameter during a submaximal sustained isometric contraction. In a randomised,
double-blind, crossover design, healthy men (n = 13, age: 25 ± 4 years, BMI: 25 ± 3 kg·m−2, mean
± SD) ingested New Zealand blackcurrant (NZBC) extract (600 mg·day−1 CurraNZ™) or placebo (PL) for
7-days separated by 14-days washout. Participants produced isometric maximal voluntary contractions
(iMVC) and a 120-s 30%iMVC of the quadriceps with electromyography (EMG), near-infrared
spectroscopy, hemodynamic and ultrasound recordings. There was no effect of NZBC extract on iMVC
(NZBC: 654 ± 73, PL: 650 ± 78 N). During the 30%iMVC with NZBC extract, total peripheral
resistance, systolic, diastolic, and mean arterial pressure were lower with increased cardiac
output and stroke volume. With NZBC extract, EMG root mean square of the vastus medialis and muscle
oxygen saturation were lower with higher total haemoglobin. During the 30%iMVC, femoral artery
diameter was increased with NZBC extract at 30 (6.9%), 60 (8.2%), 90 (7.7%) and 120 s (6.0%).
Intake of NZBC extract for 7-days altered cardiovascular responses, muscle oxygen saturation,
muscle activity and femoral artery diameter during a 120-s 30%iMVC of the quadriceps. The present
study provides insight into the potential mechanisms for enhanced exercise performance with intake
of blackcurrant.