Purpose It has been previously shown that New Zealand blackcurrant (NZBC) extract increased fat oxidation during short duration cycling. The present study examined the effect of different doses of NZBC extract on substrate oxidation and physiological responses during prolonged cycling.
Methods Using a randomized counterbalanced Latin square design, 15 endurance trained male cyclists (age: 38±12 yrs, height: 187±5 cm, body mass: 76±10 kg, V̇O2max: 56±8 mL∙kg-1∙min-1, mean±SD) completed four separate 120 minutes cycling bouts at 65% V̇O2max after ingesting no dose, or one of three doses (300, 600 or 900 mg∙day-1) of NZBC extract (CurraNZTM) for 7-days.
Results A dose effect (P<0.05) was observed for average fat oxidation (0, 300, 600 and 900 mg∙day-1 values of 0.63±0.21; 0.70±0.17; 0.73±0.19 and 0.73±0.14 g∙min-1) and carbohydrate oxidation (0, 300, 600, 900 mg∙day-1 values of 1.78±0.51, 1.65±0.48, 1.57±0.44, and 1.56±0.50 g∙min-1). The individual percentage change of mean fat oxidation was 21.5% and 24.1% for 600 and 900 mg∙day-1 NZBC extract, respectively, compared to no dose. Heart rate, V̇O2, V̇CO2, plasma lactate and glucose were not affected.
Conclusion Seven-days intake of New Zealand blackcurrant extract demonstrated a dose-dependent effect on increasing fat oxidation during 120 minutes cycling at 65% V̇O2max in endurance-trained male cyclists.