Fish oil reduces heart rate and oxygen consumption during exercise.
Dietary omega-3 polyunsaturated fatty acids (PUFAs) are readily incorporated into heart and skeletal muscle membranes where, in the heart, animal studies show they reduce O2 consumption. To test the hypothesis that omega-3 PUFAs alter O2 efficiency in humans, the effects of fish oil (FO) supplementation on O2 consumption during exercise were evaluated. Sixteen well-trained men (cyclists), randomly assigned to receive 8 x 1 g capsules per day of olive oil (control) or FO for 8 weeks in a double-blind, parallel design, completed the study (control: n = 7, age 27.1 +/- 2.7 years; FO: n = 9, age 23.2 +/- 1.2 years). Subjects used an electronically braked cycle ergometer to complete peak O2 consumption tests (VO 2peak) and sustained submaximal exercise tests at 55% of peak workload (from the VO 2peak test) before and after supplementation. Whole-body O2 consumption and indirect measurements of myocardial O2 consumption [heart rate and rate pressure product (RPP)] were assessed. FO supplementation increased omega-3 PUFA content of erythrocyte cell membranes. There were no differences in VO 2peak (mL kg(-1) min(-1)) (control: pre 66.8 +/- 2.4, post 67.2 +/- 2.3; FO: pre 68.3 +/- 1.4, post 67.2 +/- 1.2) or peak workload after supplementation. The FO supplementation lowered heart rate (including peak heart rate) during incremental workloads to exhaustion (P < 0.05). In addition, the FO supplementation lowered steady-state submaximal exercise heart rate, whole-body O2 consumption, and RPP (P < 0.01). Time to voluntary fatigue was not altered by FO supplementation. This study indicates that FOs may act within the healthy heart and skeletal muscle to reduce both whole-body and myocardial O2 demand during exercise, without a decrement in performance.
Peoples
Gregory E
GE
Smart Foods Centre, School of Health Sciences, University of Wollongong, Wollongong, NSW, Australia. peoples@uow.edu.au
McLennan
Peter L
PL
Howe
Peter R C
PR
Groeller
Herbert
H
D000284:Administration, Oral; D000328:Adult; D002214:Capsules; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000008:administration & dosage; D004311:Double-Blind Method; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005395:Fish Oils / Q000008:administration & dosage* / Q000097:blood; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D008563:Membrane Lipids / Q000097:blood; D018763:Muscle Fatigue / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D013997:Time Factors; D055815:Young Adult
D002214:Capsules; D005395:Fish Oils; D008563:Membrane Lipids; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid