Author(s): BRANDENBURG, J., GILES, L., Institution: UNIVERSITY OF THE FRASER VALLEY, Country: CANADA, Abstract-ID: 1550

INTRODUCTION:
Blueberries, due to their rich polyphenol content, have antioxidant properties. Considering the excess production of reactive oxygen species is connected to the development of fatigue, supplementation with blueberries may serve to benefit performance. The potential ergogenic effect of blueberry supplementation is not well understood, as is the identification of any mechanisms underlying any performance-enhancing effect. The objectives were to examine the effect of 4 days of blueberry supplementation on metabolic and heart rate (HR) responses to three submaximal intensities of cycling as well as on the performance of 4 and 2 km cycling time-trials.
METHODS:
Using a double-blind randomized cross-over design, 16 participants (11 M, 5 F) with cycling experience completed three sessions (height: 178.8 ± 9.0 cm, body mass: 77.0 ± 11.4 kg, age: 41 ± 10 years, VO2max: 49.7 ± 6.9 ml·kg-1·min-1). Following a familiarization session, participants completed two experimental sessions: one following 4 days of supplementation with freeze-dried highbush blueberry powder (BLU) and the other following 4 days of supplementation with a placebo (PLA). Participants performed 22 minutes of submaximal intensity cycling (4-min warm-up, 3 × 6 min at 40%, 55%, and 70% of power at VO2max), followed by a 4 km and a 2 km time-trial. HR, blood lactate (Blac), and expired gases were collected throughout the submaximal intensity cycling. HR and Blac were also assessed during each time-trial. A 2 x 3 (supplement x intensity [40%, 55%, and 70%]) repeated measures ANOVA was used to assess differences HR, VO2, RER, and blood lactate during submaximal cycling. Paired sample t-tests were used to assess differences in time trial performance, HR, and Blac during each time-trail.
RESULTS:
There was a main effect of supplement for Blac, which was significantly lower following supplementation (p=0.024; BLU 3.8 ± 1.1 vs. PLA 4.7 ± 019). There were no differences in HR, VO2 or RER during submaximal cycling (p>0.05; BLU vs PLA: HR40 119 ± 11 vs. 120 ± 10; HR55 138 ± 12 vs. 139 ± 12; HR70 159 ± 12 vs. 160 ± 11; VO240 25.5 ± 3.3 vs. 26.3 ± 3.1; VO255 32.4 ± 4.9 vs. 32.9 ± 4.1; VO270 40.8 ± 5.6 vs. 40.8 ± 5.4; RER40 0.92 ± 0.04 vs. 0.94 ± 0.06; RER55 0.95 ± 0.04 vs.0.96 ± 0.05, RER70 1.01 ± 0.05 vs. 1.01 ± 0.05). There were no differences in 2 km and 4 km time trial performance between supplement conditions (p>0.05; BLU vs. PLA: 2km 206 ± 30 vs. 202± 23 s; 4 km 413 ± 53 vs. 413 ± 43) or the HR and Blac responses to either time-trial (p> 0.05).
CONCLUSION:
Four days of supplementation with freeze-dried blueberry powder yielded a lower blood lactate response across all 3 submaximal cycling intensities. There were no other differences in any other physiological variables nor were there any differences in 2 or 4 km time-trial performance. Although the ingestion of blueberries appears to alter the metabolic response to submaximal exercise, there is no benefit to high-intensity exercise performance.