Intake Duration of Anthocyanin-Rich New Zealand Blackcurrant Extract Affects Metabolic Responses during Moderate Intensity Walking Exercise in Adult Males

We examined effects of intake duration of anthocyanin-rich New Zealand blackcurrant (NZBC) extract on physiological and metabolic responses during moderate intensity walking. Healthy men (n = 16, age: 24 ± 6 years, body mass: 78 ± 16 kg, BMI: 24.7 ± 4.1 kg·m^-2, body fat: 15 ± 5%) volunteered. One metabolic equivalent (1-MET: 3.95 ± 0.64 ml·kg^-1·min^-1) was measured during supine rest. Responses during the 30-min walk (n = 3: 4-MET; n = 13: 5-MET) (speed: 5.7 ± 0.7 km·hr^-1) were measured at 7-10, 17-20 and 27-30 min and averaged over the time periods. For intake conditions (7-days and 14-days), two capsules of NZBC extract (600 mg containing 210 mg of anthocyanins) were taken with breakfast (14-day washout). The final two capsules were ingested 2-hr before the morning walk. Intake duration of NZBC extract had no effect on heart rate, minute ventilation, oxygen uptake, and carbon dioxide production. Fat oxidation was enhanced with 7- and 14-day intake by 11 ± 19% and 17 ± 26% (baseline: 0.36 ± 0.12, 7-day: 0.39 ± 0.13, 14-day: 0.41 ± 0.13 g·min^-1, p = 0.007). Only 14-day intake lowered RER (baseline: 0.852 ± 0.046, 7-day: 0.843 ± 0.045, 14-day: 0.837 ± 0.037, p = 0.019) and carbohydrate oxidation (baseline: 0.95 ± 0.40, 7-day: 0.91 ± 0.40, 14-day: 0.86 ± 0.33 g·min^-1, p = 0.032). Rating of perceived exertion was lower with 7-day and 14-day intake (baseline: 11.0 ± 2.3, 7-day: 10.5 ± 1.8, 14-day: 10.3 ± 2.1, p = 0.002). Longer intake duration (i.e. 14 days) of New Zealand blackcurrant extract seems to enhance fat oxidation more during a 30-min moderate intensity walk than 7 days intake. The intake duration of anthocyanin-rich New Zealand blackcurrant extract may be due to an enhanced bioavailability of anthocyanin-derived metabolites that alter the mechanisms for substrate oxidation during moderate intensity exercise.

Keywords: Brisk walking; anthocyanins; exercise-induced fat oxidation; metabolic equivalent; respiratory exchange ratio.