DHA-rich fish oil lowers heart rate during submaximal exercise in elite Australian Rules footballers

Omega-3 fatty acids (n-3) can improve cardiovascular (CV) function. This study examined the effects of n-3 on endurance performance, recovery and CV risk factors in elite Australian Rules football players. 25 players were randomised, double-blind, to 6 g/day of docosahexaenoic acid (DHA)-rich fish oil (FO; n = 12) or sunflower oil (SO; n = 13) during 5 weeks of training. At baseline erythrocyte n-3 content, resting blood pressure (BP), fasting serum triglycerides (TG) and heart rate (HR) during treadmill running at 10 km/h were assessed. Two treadmill runs (T1 and T2) to exhaustion, separated by 5 min, were then performed at the average speed for a recent 2200 111 time-trial. After 5 weeks, erythrocyte n-3 increased (FO 3.8 +/- 0.6%, SO 0.6 +/- 0.3%; P<0.001) while TG (FO -0.32 +/- 0.09 mmol l(-1), SO 0.08 +/- 0.05 mmol l(-1); P<0.001), diastolic BP (FO 1.3 +/- 1.3 mmHg, SO 6.8 +/- 1.7 mmHg; P=0.04) and FIR during submaximal exercise (FO -7.8 +/- 2.3 beats min(-1), SO -1.9 +/- 1.9 beats min(-1); P=0.03) decreased in FO compared with SO. Time to exhaustion (TTE) during T1 increased by Week 5 (FO 10.2 +/- 2.2%, SO 17.3 +/- 4.3%; P < 0.001 for time). Recovery (TTE for T2 as % T1) decreased in both groups (FO, -3.4 +/- 4.5%, SO -8.8 +/- 3.9%; P = 0.05 for time). We conclude that 5 weeks of supplementation with FO improved CV function and reduced CV risk factors, but did not improve endurance performance or recovery in elite Australian Rules footballers. (C) 2008 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.