Background: Rugby union is a contact team sport with athletes requiring multiple performance abilities. New Zealand blackcurrant (NZBC) extract has provided enhanced effects for aerobic and anaerobic exercise tasks for endurance and team sports athletes (doi: 10.1007/s00421-015-3215-8 and doi: 10.1123/ijsnem.2015-0020). The mechanisms for enhanced exercise performance by intake of NZBC extract are still unclear. Previous performance studies on the effects by NZBC extract used mainly a single exercise task. We examined the effects of NZBC extract on the repeated performance in a battery of rugby union specific tests including speed, agility and strength testing.

Methods: University males rugby union players (n=13, age: 21±2 years, height: 182±6 cm, body mass: 86.9±13.3 kg) completed two full familiarisations and two experimental visits in an indoor facility. The study had a double blind, placebo-controlled randomised crossover design. For the experimental visits, participants consumed two capsules a day for seven days of NZBC extract (210 mg/day of anthocyanins) or placebo with a 7-day wash out. Participants were tested for performance in the following order: Running-based anaerobic sprint test, the Illinois agility test, seated medicine ball (3 kg) throw, and hand grip strength. Data were analysed with two-tailed student t-tests with significance accepted at p≤0.05 and interpretation of 0.05>p≤ 0.1 as a trend.

Results: With NZBC extract, there was a strong trend for average sprint time to be higher by 1.7% (placebo: 5.947±0.538 s, NZBC extract: 5.846±0.571 s, p=0.06) with 6 participants having changes of more than 3%. In the Illinois agility test, there was also a strong trend for the mean time to be higher by 1.6% (placebo: 18.46±1.44 s, NZBC extract: 18.15±1.22 s, p=0.07) with 4 participants having changes of more than 3%. The correlation between the %change in average sprint time and %change in the mean agility time was not significant (pearson R2=0.0698, p=0.383). There were no differences for the seated medicine ball throw (p=0.106) and hand grip strength (p=0.709).

Conclusions: Intake of anthocyanin-rich NZBC extract in rugby union players seems to improve tasks that require speed and agility but not muscle strength. NZBC blackcurrant extract may be able to enhance exercise performance in team sports that require repeated movements with high intensity and horizontal change of body position without affecting muscle strength.

Acknowledgements: Supplementation was provided by Health Currancy Ltd (United Kingdom) and CurraNZ Ltd (New Zealand). Financial support for conference attendance was obtained from Blackcurrant New Zealand Inc (New Zealand).