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B-34 Free Communication/Poster - Ergogenic Aids IV Wednesday, June 1, 2016, 1: 00 PM - 6: 00 PM Room: Exhibit Hall A/B

Combined Effects of Ischemic Preconditioning and Nitrate Supplementation on Submaximal Cycling Exercise and Time-trial Performance

914 Board #230 June 1, 3

30 PM - 5

00 PM

McIlvenna, Luke C.; Monaghan, Chris; Fernandez, Bernadette O.; Feelisch, Martin; Muggeridge, David J.; Easton, Chris

Author Information
Medicine & Science in Sports & Exercise: May 2016 - Volume 48 - Issue 5S - p 258
doi: 10.1249/01.mss.0000485777.74366.23
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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 (Δ104 ± 149 nM, d=0.70) and DN (Δ42 ± 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.

© 2016 American College of Sports Medicine