The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Effect of Blackcurrant consumption and physical fatigue on cognitive performance.
Scientific title
Relationship between the consumption of a blackcurrant supplement and exercise-induced fatigue on mental acuity and cognitive performance in healthy volunteers.
Secondary ID [1] 285060 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
The primary aim of this study is to explore parameters (including interactions) that influence the preservation and / or enhancement of mental health (acuity and functioning) after physical fatigue (induced by repetition of a Wingate cycle test) and /or consumption of a blackcurrant extract. 292584 0
Condition category
Condition code
Mental Health 292888 292888 0 0
Studies of normal psychology, cognitive function and behaviour

Study type
Description of intervention(s) / exposure
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.
Intervention code [1] 289896 0
Intervention code [2] 289923 0
Treatment: Other
Intervention code [3] 289924 0
Comparator / control treatment
Opaque gelatin capsule containing the equivalent sugar (fructose and glucose) present in the blackcurrant extract.
Control group

Primary outcome [1] 292763 0
Cognitive performance
Timepoint [1] 292763 0
Cognitive performance will be assessed at a familiarisation session as well as in the main part of the trial. In the main trial, participants will be asked to perform a series of computerised tasks designed to test cognitive functioning prior to and immediately after either (a) performing repeated (usually 4-5) 30 second Wingate cycle tests designed to induce a physical fatigue or (b) a 10 min relaxation period. Cognitive performance will be tested using 5 tasks; stroop, digit symbol substitution, backward digit span, trail making and complex reaction time, which examine various aspects of cognitive processing.

Primary outcome [2] 292795 0
Physical exercise performance
Timepoint [2] 292795 0
Exercise performance is assessed on a stationary cycle ergometer, participants will be asked to cycle at maximum speed at braking torque (4% body weight) for 30 seconds. Using the participant’s physical performance measures; cycle work output [peak/average], physical fatigue index, lactate threshold [anaerobic capacity], blood glucose and ratings of perceived exertion parameters, we aim to assess changes in physical performance in the main trial before and after exercise-induced fatigue or 10 min relaxation.
Secondary outcome [1] 309620 0
Oxidative stress and antioxidant paramters
Timepoint [1] 309620 0
Changes in oxidative stress and antioxidant status will be measured at specific times during the main trial; (i) pre-treatment; blackcurrant or placebo, (ii) just before and (iii) immediately after exercise-induced fatigue or relaxation period, and finally (iv) after a 20 minutes recovery period. We will measure changes in the following plasma oxidative stress parameters, (a) radical oxygen species using fluorescence assay using hydrolysed DCF, (b) superoxide, (c) nitric oxide, (d) protein carbonyls and (e) lipid peroxidation – malondialdehyde (MDA) using commercially available assay kits (Abcam). Antioxidant status will be assessed by changes in superoxide dismutase, catalase and GPx activity in PBS washed (x2) erythrocytes using “in house” colorimetric bioassays and plasma total antioxidant capacity measured using hydrolysed fluorescent probe DCF and H2O2 as the pro-oxidant stimulus.
Secondary outcome [2] 309696 0
Leukcoyte mitochondrial DNA fragility
Timepoint [2] 309696 0
Mitochondrial fragility will be measured at (i) pre-treatment; blackcurrant or placebo, (ii) just before and (iii) immediately after exercise-induced fatigue or relaxation period, and finally (iv) after a 20 minutes recovery period. We aim to determine the effect of blackcurrant consumption and/or exercise-induced fatigue on mitochondrial DNA. This involves isolating leukocyte DNA and using “nested” PCR methodology using specific oilgonucleotides that recognise a specific region of mitochondrial DNA that is susceptible to oxidative stress.

Key inclusion criteria
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.
Minimum age
16 Years
Maximum age
50 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
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).

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
(a) Recruitment. Participants will be recruited from a flyer posted on the appropriate notice boards local research institutes and community gyms. All interested individuals will have an initial chat with the trial coordinator and be provided with information sheet, health and fitness questionnaires and consent forms to take home for discussion with friends, family or whanau. Potential participants will have 2 weeks to decide whether they would like to take part in the study.
(b) This is full factorial design. Particpants will allocated into one of four groups; Group 1; placebo and no exercise, Group 2; placebo and physical fatigue, Group 3; blackcurrant and no exercise and Group 4; blackcurrant and physical fatigue. Study investigators and particpants will be blinded from dietary intervention but not from the physcial intervention (relaxation or exercie-induced physical fatigue). Allocation of dietary intervention is undertaken by a fellow scientist who is not involved in this study. Participant treatment allocation is held concealed until completion of the trial and analysis of the data is finished. Furthermore, participants will be given their dietary treatmtent as an opaque gelatin capsule, which will mask the blackcurrant extract or placebo, and asked to take the treatment quickly with a galss of water. They will also be supervised so they don't attempt to pull the capsule apart.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Allocation of particpants into one of four groups will be performed using a spreadsheet random function.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s
The people administering the treatment/s
The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Only the dietary intervention is blinded in this study. Both the study participants and investigators are blinded to the dietary intervention but not the physcial intervention (i.e relaxation or exercise-induced fatigue).
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Data will be expressed as mean +/- standard error of the mean. (i) Interaction between the consumption of a blackcurrant extract and exercise-induced fatigue on cognitive performance. The effect sizes associated with the blackcurrant extract are expected to be very small. For example, if we conduct a t-test between two groups with a small effect size (Cohen’s d = 0.2), with power = 0.8 and a significance level of P< 0.05, we would need to have a total N of 788, nearly 400 per group, according to the G*Power3.1.2 programme. Hence, our concentration for this part of the study will be on effect sizes with confidence limits, and trends in the data. Future similar studies can combine the results of several studies in a meta-analysis to increase N. (ii) Biochemical data analysis. Statistical significance for the comparison between two groups will be assessed using a paired Student's t-test. Multiple comparisons will be assessed by a two-way ANOVA. Where appropriate, the original data will be transformed to achieve normality and constant variance in the residuals. Statistical significance for all indices will be set at P < 0.05 with a confidence level of 95%.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 6253 0
New Zealand
State/province [1] 6253 0
Palmerston North, Manawatu

Funding & Sponsors
Funding source category [1] 289665 0
Government body
Name [1] 289665 0
New Zealand Institute for Plant and Food Research
Address [1] 289665 0
Private Bag 11600,
Palmerston North 4442
Country [1] 289665 0
New Zealand
Primary sponsor type
Government body
New Zealand Institute for Plant and Food Research
Private Bag 92169,
Auckland 1142
New Zealand
Secondary sponsor category [1] 288356 0
Name [1] 288356 0
Address [1] 288356 0
Country [1] 288356 0
Other collaborator category [1] 278063 0
Name [1] 278063 0
Assoc. Prof. John Podd,
Address [1] 278063 0
School of Psychology
Massey University
Private Bag 11-222
Palmerston North 4442

Country [1] 278063 0
New Zealand

Ethics approval
Ethics application status
Ethics committee name [1] 291402 0
Health and Disability Ethics Committee (HDEC), New Zealand
Ethics committee address [1] 291402 0
Ministry of Health
No 1 The Terrace
PO Box 5013
Wellington 6145
Ethics committee country [1] 291402 0
New Zealand
Date submitted for ethics approval [1] 291402 0
Approval date [1] 291402 0
Ethics approval number [1] 291402 0

Brief 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.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 50234 0
Dr Suzanne Hurst
Address 50234 0
New Zealand Institute for Plant and Food Research Ltd.
Private Bag 11600
Palmerston North 4442
Country 50234 0
New Zealand
Phone 50234 0
+64 (6) 355 6231
Fax 50234 0
+64 (6) 351 7050
Email 50234 0
Contact person for public queries
Name 50235 0
Dr Dominic Lomiwes
Address 50235 0
New Zealand Institute for Plant and Food Research Ltd.
Private Bag 11600
Palmerston North 4442
Country 50235 0
New Zealand
Phone 50235 0
+64 (6) 953 6224
Fax 50235 0
+64 (6) 351 7050
Email 50235 0
Contact person for scientific queries
Name 50236 0
Dr Suzanne Hurst
Address 50236 0
New Zealand Institute for Plant and Food Research Ltd.
Private Bag 11600
Palmerston North 4442
Country 50236 0
New Zealand
Phone 50236 0
+64 (6) 355 6231
Fax 50236 0
+64 (6) 351 7050
Email 50236 0

No information has been provided regarding IPD availability
Summary results
No Results