Effect of Blackcurrant consumption and physical fatigue on cognitive performance.
Relationship between the consumption of a blackcurrant supplement and exercise-induced fatigue on mental acuity and cognitive performance in healthy volunteers.
New Zealand Institute for Plant and Food Research
60 participants
Sep 1, 2014
Interventional
Conditions
Summary
Physically active individuals have a faster and more robust cognitive processing ability than those who are sedentary. Meta analysis of randomized controlled studies, involving individuals of different ages, showed that physical exercise (even after one session) can improve mental acuity. Exercise intensity is generically thought to affect cognitive performance in an upside down, U-shaped fashion; moderate intensity exercise facilitates cognitive functioning, whereas high intensity training (HIT) may delay or impair cognition. Whilst prolonged high intensity training sessions does appear to have detrimental action on mental acuity, a recent study showed that short bursts (60 secs) of HIT improved cognitive execution. These conflicting findings suggest that the duration of the physical “fatiguing” exercise and an individual’s ability to recovery may impact upon their cognitive functioning. Although the underlying mechanisms involved in how exercise improves or preserves cognitive ability is unclear, cerebral blood flow is integral to mental acuity: A positive link between aerobic exercise, delivery of oxygenated haemoglobin to the cerebral frontal area and enhanced cognition has recently been shown. Since prolonged high intensity anaerobic exercise is shown to cause a transient decrease in the cerebral oxygenated: deoxygenated haemoglobin ratio and a delay in the removal of detrimental metabolites (e.g. lactate), changes in blood flow and oxidative stress may underlie the impaired cognitive function observed. We have shown that blackcurrant consumption alleviates oxidative stress and improves blood flow to a variety of tissues; increasing oxygen delivery to tissues and blood lactate clearance in various exercise training scenarios. It is therefore feasible that blackcurrant consumption may alleviate oxidative stress, facilitate oxygen delivery to and removal of waste by-products from, the brain during recovery from a physical “fatiguing” exercise, thereby preserving cognitive function. In this study we examine the inter-relationship between (i) cognitive performance (ii) an intensive “fatiguing” exercise and (iii) “timed” consumption of a single portion of a blackcurrant extract.
Eligibility
Inclusion Criteria1
- Healthy individuals (male or female) 19-50 years, who have not taken part in any formal fitness training for at least 4 months and are able to complete the physical requirements of the study will be selected; (i) complete a health and (ii) fitness (Baecke) questionnaires and (ii) perform the Wingate cycle test to the standard required. In addition, all particpants will provide written consent for this study.
Exclusion Criteria1
- Participants will be excluded if they are unable or unwilling to provide informed written consent or comply with the study procedures. Participants will also be excluded if they have (i) known hypersensitivity or intolerance to blackcurrants or berryfruit and/or berryfruit-derived products, (ii) have health conditions that impair ability to perform Wingate cycle exercise (e.g. injury, hernia, back or joint pain, cardiovascular and breathing problems or fail to demonstrate a certain fitness level, assessed by a Baecke questionnaire, or are unable to perform the Wingate cycle exercise to the standard required by the trial co-ordinator, and (iii) health conditions that may affect ability to do computerized cognitive tasks (e.g. eye sight problems, colour blindness, aura migraines, epilepsy). In addition, participants will be excluded if they are pregnant or planning to get pregnant in the near future or have any of the following conditions; (i) blood borne diseases (e.g. hepatitis), (ii) clinically diagnosed high/low blood pressure, (iii) recent bacterial or viral illness, (iv) are taking any medication that affects the properties of blood (e.g. blood clotting).
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Interventions
This is a full factorial study design that will allow us to test the effect of both physical fatigue and efficacy of blackcurrant nutritional intervention on cognitive performance as well as identify potential interactions. Participants will be randomised into one of the four treatment groups; Group 1; placebo and no exercise, Group 2; placebo and intensive “fatiguing” exercise, Group 3; blackcurrant extract and no exercise and Group 4; blackcurrant extract and intensive “fatiguing” exercise. The blackcurrant extract used in this study is made commercially by Just-the-Berries (Nelson, NZ), and is an anthocyanin rich (freeze-dried) extract (30%) made entirely of New Zealand Blackcurrants. Furthermore, the dose used in this study is ~ 1g (equivalent to 250 mg anthocyanins). On the day of the trial, participants will be asked to consume a gelatine capsule containing either a blackcurrant extract or placebo (equivalent fructose and glucose), after 1 hour they will be asked to either to relax for 10 minutes or perform Wingate cycle test (30 second cycle at maximum power [80-100 watts] on a stationary ergometer with a 4% body weight braking torque) with a 1 min resting interval until they fatigue (usually 4-5 repeats); indicated by a drop in power output in the last 10 seconds of the 30 second cycle or verbal indication by the participant. The participant will then be asked to repeat the cognitive performance task followed by another 30 second “Wingate” test using the same conditions described above.
Locations(1)
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ACTRN12614000829617