The effect of acute New Zealand blackcurrant juice consumption on motivation to exercise.

Background: Consumption of a blackcurrant polyphenolic extract in healthy individuals prior to a cognitive challenge improved cognitive performance and mood.  Although the underlying causes are unknown, a change in neurotransmitter concentrations involved in motivation was detected.  Since motivation is key to the desire and adherence to exercise, we hypothesised that consuming blackcurrant juice prior to exercise improves voluntary physical activity by increasing motivation.

Methods:  Forty healthy participants consumed either a New Zealand blackcurrant juice concentrate; New Zealand Blackcurrant Co-operative (BC) diluted to deliver a dose of 3.9 mg anthocyanins/ kg bodyweight or a sugar-matched placebo (PL) drink. Participants then exercised on a treadmill, walking a t a semi-brisk pace (50% of estimated maximal heart rate) where information on time and distance walked was concealed.  During the exercise, participant’s mood and perceived exertion was assessed and the exercise was stopped when participant’s mood scores became consistently negative or started show signs of fatigue (>2 hr).  Blood samples were collected and analysed for various biomarkers.

Results:  Exercise-induced changes in heart rate, blood lactate and oxidative stress were similar in both PL and BC groups.  The mean time and distances walked by the BC group was longer than the PL group and BC participants recorded a significantly higher number of ‘positive’ mood scores throughout the exercise.  A significant decrease (p<0.001) in plasma MAO-B activity (an enzyme that degrades monoamine transmitters) was detected in the BC group.  Plasma prolactin levels (an indirect biomarker for dopamine concentrations) after exercise was significantly reduced in the BC group (p<0.05), but not in the PL group (p=0.304).

Conclusions:  These results suggest that blackcurrant consumption prior to exercise supports motivation and desire to exercise for longer.  This may be through blackcurrant compounds modulating monoamine neurotransmitter levels (e.g. dopamine, serotonin, noradrenaline) during exercise that influence mood and motivation.

Dominic Lomiwes1*, Suzanne Hurst1, Birgit Ha1, Nayer Ngametua1, Natalie Burr1, Roger Hurst1

1Food and Wellness Group, The New Zealand Institute for Plant & Food Research Limited

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