Intrinsic heart rate recovery after dynamic exercise is improved with an increased omega-3 index in healthy males. Issue 12 (28th December 2014)

• Record Type: Journal Article
• Authors: Macartney, Michael J.; Hingley, Lachlan; Brown, Marc A.; Peoples, Gregory E.; McLennan, Peter L.
• Is Part Of: British journal of nutrition. Volume 112:Issue 12(2014)
• Page Start: 1984
• Page End: 1992
• Publication Date: 2014-12-28
• Subjects: Nutrition -- Periodicals; 572.4
• DOI: 10.1017/S0007114514003146
• Languages: English
• ISSNs: 0007-1145

Abstract

<abstract abstract-type="normal"> <title> <x content-type="archive" xml:space="preserve">Abstract</x> </title> <p>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 (<italic>n</italic> 26) were supplemented (double-blind, parallel design) with (2 × 1 g/d) soya bean oil (control) or tuna FO providing the long-chain <italic>n</italic>-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 (<sc>sem</sc> 0·2), <italic>n</italic> 13; FO 4·7 (<sc>sem</sc> 0·2), <italic>n</italic> 13), remained unchanged in the control group (3·9 (<sc>sem</sc> 0·2)), but increased in the FO group (6·3 (<sc>sem</sc> 0·3); <italic>P</italic>< 0·01). The mean HR during supine resting conditions (control 56 (<sc>sem</sc> 10); FO 59 (<sc>sem</sc> 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 (<sc>sem</sc> 0·01); FO − 0·05 (<sc>sem</sc> 0·02); <italic>P</italic>= 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 (<sc>sem</sc> 6) ( = − 4·5 beats/min)), but not in the control group (+1 (<sc>sem</sc> 4)) (<italic>P</italic>< 0·05). Supine HR recovery (half-time) after cycling was significantly faster after FO supplementation (control − 0·4 (<sc>sem</sc> 1·2) s; FO − 8·0 (<sc>sem</sc> 1·7) s; <italic>P</italic>< 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.</p> </abstract>