DHA-rich Fish Oil Increases the Omega-3 Index and Lowers the Oxygen Cost of Physiologically Stressful Cycling in Trained Individuals.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 28338369 · doi:10.1123/ijsnem.2016-0150
What was done
Twenty-six trained male participants were enrolled in a double-blind randomized trial receiving either control (2 x 1 g/day soy oil) or DHA-rich tuna fish oil (560 mg DHA and 140 mg EPA daily) for 8 weeks. Baseline and 8-week assessments included the Omega-3 Index, maximal cycling sprint power (3 x 6 s), isometric quadriceps maximal voluntary contraction force, a repeated Wingate protocol (6 x 30 s), and power output and oxygen consumption during a 5-minute cycling time trial.
What was found
The Omega-3 Index increased in the fish oil group compared to control (FO: from 4.7 ± 0.2% to 6.3 ± 0.3%; Control: from 4.2 ± 0.2% to 3.9 ± 0.2%, p < .01). Relative oxygen consumption during the 5-minute time trial was reduced in the fish oil group (change of -154 ± 59 ml O2/min/100W in FO versus -23 ± 26 ml O2/min/100W in Control, p < .05). No significant effects were observed for 6-second sprint power (Control: Pre 1100 ± 49 W, Post 1067 ± 51 W; FO: Pre 1070 ± 46 W, Post 1042 ± 46 W), 5-minute time-trial power (Control: Pre 267 ± 19 W, Post 278 ± 20 W; FO: Pre 253 ± 16 W, Post 265 ± 16 W), or maximal voluntary contraction force (Control: Pre 273 ± 19 Nm, Post 251 ± 19 Nm; FO: Pre 287 ± 17 Nm, Post 283 ± 16 Nm).
Why it matters
DHA-rich fish oil supplementation increases the Omega-3 Index and improves cycling economy by lowering oxygen demand during intense cycling. However, this physiological efficiency did not translate into improvements in short-duration sprint power, time-trial power output, or muscle strength.
Limits
The study had a small sample size of 26 trained males, limiting generalizability to females and untrained populations. Skeletal muscle membrane incorporation was inferred rather than directly measured, and longer endurance exercise protocols were not evaluated.
Cited by
- supports Studies from Australia showed that omega-3 supplementation, particularly DHA, can reduce the oxygen cost of exercise and lower heart rate.