Combined effects of ischemic preconditioning and nitrate supplementation on submaximal cycling exercise and time-trial performance

McIlvenna, Luke C and Monaghan, Chris and Fernandez, Bernadette O and Feelisch, Martin and Muggeridge, David J. and Easton, Chris (2016) Combined effects of ischemic preconditioning and nitrate supplementation on submaximal cycling exercise and time-trial performance. In: American College of Sports Medicine Annual Meeting, 2016-05-31 - 2016-06-04.

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Abstract

Ischemic preconditioning (IPC) and dietary nitrate supplementation (DN) have both been shown to modulate nitric oxide (NO) availability. Despite the possibility of a synergistic response, the combined effects of IPC and DN during exercise have yet to be explored.PURPOSE: To determine the effects of IPC alone and in combination with DN on the physiological responses to submaximal cycling and time trial (TT) performance.METHODS: Following an initial maximal exercise test, nine competitive male cyclists (34 ± 6 Yr, V[Combining Dot Above]O2peak: 55 ± 4 mL/kg/min) completed a baseline trial (BASE), and two experimental trials in a double-blind randomized cross-over design. Exercise trials comprised 6 min of cycling at 80% of the ventilatory threshold, followed by a 16.1 km TT. In the experimental trials participants received either 500 mg of DN (chard gel) or a NO3--depleted placebo (PLA) 90 min before completing three cycles of bilateral lower limb IPC at 180 mmHg. Venous blood samples were collected pre- and post-IPC to determine changes in plasma nitrite [NO2-]. V[Combining Dot Above]O2 and HR were continuously monitored during submaximal exercise.RESULTS: Full arterial occlusion was confirmed via coloured Doppler in all trials. Prior to IPC, plasma [NO2-] was higher in DN (774 ± 179 nM, P=0.047) than BASE (576 ± 170 nM) and PLA (544 ± 126 nM, P=0.752). Following IPC plasma [NO2-] increased in PLA (?104 ± 149 nM, d=0.70) and DN (?42 ± 90 nM, d=0.47), but not significantly (both P>0.2). In the DN trial, resting V[Combining Dot Above]O2 was significantly lower compared to BASE (314 ± 69 vs. 367 ± 30 mL/min, P=0.02) and tended to be lower during exercise (P=0.066). Resting V[Combining Dot Above]O2 was also lower in PLA than BASE (323 ± 62 mL/min, P=0.01) and during exercise (2783 ± 262 vs. 3013 ± 342 mL/min, P=0.04). HR was not significantly different in submaximal exercise (P=0.842). Completion time of TT was not different between conditions (BASE: 1336 ± 73 s, PLA: 1344 ± 88 s, DN: 1344 ± 76 s, P=0.69). Compared to BASE (171 ± 4 bpm), HR was lower following DN (166 ± 4 bpm, P=0.02) but was not different in PLA (169 ± 4 bpm, P=0.60).CONCLUSION: In the present study, IPC with or without DN, altered a number of physiological responses during rest and submaximal exercise, potentially mediated by an increase in plasma [NO2-]. Despite this, there was no evidence for an additive effect and neither intervention altered TT performance.

ORCID iDs

McIlvenna, Luke C, Monaghan, Chris, Fernandez, Bernadette O, Feelisch, Martin, Muggeridge, David J. ORCID logoORCID: https://orcid.org/0000-0003-2630-2384 and Easton, Chris;
CORE (COnnecting REpositories)