Fish oil reduces heart rate and oxygen consumption during exercise.
Level 2 - randomized trial
Double-blind randomized controlled trial
PubMed 19034030 · doi:10.1097/FJC.0b013e3181911913
What was done
Sixteen well-trained male cyclists completed a double-blind, parallel-group randomized controlled trial comparing 8 g/day of fish oil (n = 9, age 23.2 ± 1.2 years) against 8 g/day of olive oil control (n = 7, age 27.1 ± 2.7 years) for 8 weeks. Participants underwent cycle ergometer testing before and after supplementation to determine peak oxygen consumption (VO2peak) and responses during sustained submaximal exercise at 55% of peak workload. Outcomes included erythrocyte membrane omega-3 fatty acid incorporation, whole-body O2 consumption, heart rate, and rate pressure product (RPP).
What was found
Fish oil supplementation significantly increased erythrocyte omega-3 PUFA content. There were no changes in VO2peak (control: 66.8 ± 2.4 pre to 67.2 ± 2.3 mL/kg/min post; fish oil: 68.3 ± 1.4 pre to 67.2 ± 1.2 mL/kg/min post), peak workload, or time to voluntary fatigue. Fish oil significantly reduced heart rate during incremental exercise to exhaustion (P < 0.05), as well as steady-state submaximal heart rate, whole-body O2 consumption, and RPP (P < 0.01). Specific numerical values for submaximal reductions were not reported in the abstract.
Why it matters
The findings indicate that dietary omega-3 fatty acids can lower both myocardial and whole-body oxygen demand during exercise in humans, improving physiological oxygen efficiency without impairing peak performance.
Limits
The trial had a very small sample size (n = 16) and included exclusively young, well-trained male cyclists, limiting applicability to women, untrained individuals, or clinical populations. Exact values, effect sizes, and variance for submaximal endpoints were not reported in the abstract.
Cited by
- supports Studies from Australia showed that omega-3 supplementation, particularly DHA, can reduce the oxygen cost of exercise and lower heart rate.