No Effect of Acute or Chronic New Zealand Blackcurrant Extract on Cycling Performance or Physiological Responses in Trained Cyclists

Previous research examining the ergogenic benefits of blackcurrant supplementation (BC) on exercise performance is contradictory. The BC supplementation period in many studies has typically been chronic (> 6-days), with a final dose taken hours before testing. Whether any observed performance benefits are from the acute dose or chronic supplementation is unclear. This study aimed to examine the effects on cycling performance of a single-acute dose and 7-day supplementation with BC extract. This study was a placebo-controlled, double-blind, randomised, cross-over trial. Sixteen cyclists (mean ± SD: age 37 ± 11 years; height 175.8 ± 7.6 cm; body mass 73.2 ± 12.5 kg; V̇O_2peak 3.8 ± 0.7 L·min^-1) completed a total of six experimental sessions (2 × 3 treatment blocks). Each treatment block consisted of a no-supplement baseline trial, a single dose (acute) and a 7-day (chronic) supplementation trial. During each trial, subjects completed a maximal incremental test and 4 km time trial, separated by 15 min of recovery. Respiratory data, heart rate, muscle oxygenation and performance power were measured continuously in each trial, and differences between treatments were determined using RM-ANOVA and effect size analysis. There was no significant difference (p > 0.05) in cycling performance between experimental and placebo treatments following acute or chronic supplementation periods. There were no significant effects on measured physiological and metabolic parameters, and any observed differences in performance or physiology were trivial to small. Blackcurrant supplementation delivered either acutely or over a period of 7 days had no significant effect on cycling performance or physiology. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry: ACTRN12622001277730.