title: Intrinsic heart rate recovery after dynamic exercise is improved with an increased omega-3 index in healthy males.
abstract: Dietary fish consumption contributes to a reduced risk of cardiac mortality. In the present study, the effect of low-dose fish oil (FO) supplementation on heart rate (HR) response to intense exercise and recovery was investigated in physically fit males. The subjects (n 26) were supplemented (double-blind, parallel design) with (2 × 1 g/d) soya bean oil (control) or tuna FO providing the long-chain n-3 PUFA DHA (560 mg) and EPA (140 mg). Erythrocyte omega-3 index (%EPA+DHA), HR, HR variability and HR recovery were analysed during rest, intense exercise and recovery at baseline and after 8 weeks of supplementation. The mean erythrocyte omega-3 index, which did not differ between the groups at baseline (control 4.2 (sem 0.2), n 13; FO 4.7 (sem 0.2), n 13), remained unchanged in the control group (3.9 (sem 0.2)), but increased in the FO group (6.3 (sem 0.3); P< 0.01). The mean HR during supine resting conditions (control 56 (sem 10); FO 59 (sem 9)) was not affected by FO supplementation. Poincaré analysis of HR variability at rest exhibited a decreasing trend in parasympathetic activity in the FO group (SD1 (standard deviation of points perpendicular to the axis of line of identity)/SD2 (standard deviation of points along the axis of line of identity): control 0.02 (sem 0.01); FO - 0.05 (sem 0.02); P= 0.18). Peak HR was not affected by supplementation. However, during submaximal exercise over 5 min, fewer total heart beats were recorded in the FO group (-22 (sem 6) ( = -4.5 beats/min)), but not in the control group (+1 (sem 4)) (P< 0.05). Supine HR recovery (half-time) after cycling was significantly faster after FO supplementation (control - 0.4 (sem 1.2) s; FO - 8.0 (sem 1.7) s; P< 0.05). A low intake of FO increased the omega-3 index and reduced the mean exercise HR and improved HR recovery without compromising the peak HR. A direct influence of DHA via reductions in the cardiac intrinsic beat rate was balanced by a reciprocal decrease in vagal tone.
authors.affiliation: School of Medicine, Medical and Exercise Science, Centre for Human and Applied Physiology, University of Wollongong,Wollongong,NSW2522,Australia.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Macartney
authors.affiliation: School of Medicine, Medical and Exercise Science, Centre for Human and Applied Physiology, University of Wollongong,Wollongong,NSW2522,Australia.
authors.forename: Lachlan
authors.initials: L
authors.lastname: Hingley
authors.affiliation: School of Medicine, Medical and Exercise Science, Centre for Human and Applied Physiology, University of Wollongong,Wollongong,NSW2522,Australia.
authors.forename: Marc A
authors.initials: MA
authors.lastname: Brown
authors.affiliation: School of Medicine, Medical and Exercise Science, Centre for Human and Applied Physiology, University of Wollongong,Wollongong,NSW2522,Australia.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Peoples
authors.affiliation: School of Medicine, Graduate School of Medicine, Centre for Human and Applied Physiology, University of Wollongong,Wollongong,NSW2522,Australia.
authors.forename: Peter L
authors.initials: PL
authors.lastname: McLennan
mesh_terms: D000328:Adult; D000818:Animals; D001642:Bicycling / Q000502:physiology*; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000097:blood / Q000494:pharmacology; D004311:Double-Blind Method; D015118:Eicosapentaenoic Acid / Q000097:blood / Q000494:pharmacology; D004912:Erythrocytes / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D015525:Fatty Acids, Omega-3 / Q000097:blood / Q000494:pharmacology*; D005395:Fish Oils / Q000097:blood / Q000494:pharmacology; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D010275:Parasympathetic Nervous System; D005082:Physical Exertion / Q000502:physiology*; D012146:Rest / Q000502:physiology; D014413:Tuna; D055815:Young Adult
chemical_list: D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D004281:Docosahexaenoic Acids; D015118:Eicosapentaenoic Acid