Dose effects of New Zealand blackcurrant on substrate oxidation and physiological responses during prolonged cycling

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 counter balanced Latinsquare design, 15 endurance-trained male cyclists (age: 38 +/- 12 years, height: 187 +/- 5 cm, body mass: 76 +/- 10 kg,. VO(2)max: 56 +/- 8 mL kg(-1) min(-1), and mean +/- SD) completed four separate 120-min cycling bouts at 65%. VO(2)max after ingesting no dose, or one of three doses (300, 600, or 900 mg day(-1)) of NZBC extract (CurraNZ (TM)) 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, and 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,. VO2,. VCO2, plasma lactate, and glucose were not affected. Conclusion Seven-day intake of New Zealand blackcurrant extract demonstrated a dose-dependent effect on increasing fat oxidation during 120-min cycling at 65% VO(2)max in endurance-trained male cyclists.