Lower limb ischemic preconditioning combined with dietary nitrate supplementation does not influence time-trial performance in well-trained cyclists.

OBJECTIVES

Dietary nitrate (NO) supplementation and ischaemic preconditioning (IPC) can independently improve exercise performance. The purpose of this study was to explore whether NO supplementation, ingested prior to an IPC protocol, could synergistically enhance parameters of exercise.

DESIGN

Double-blind randomized crossover trial.

METHODS

Ten competitive male cyclists (age 34±6years, body mass 78.9±4.9kg, V⋅O 55±4 mLkgmin) completed an incremental exercise test followed by three cycling trials comprising a square-wave submaximal component and a 16.1km time-trial. Oxygen uptake (V⋅O) and muscle oxygenation kinetics were measured throughout. The baseline (BASE) trial was conducted without any dietary intervention or IPC. In the remaining two trials, participants received 3×5min bouts of lower limb bilateral IPC prior to exercise. Participants ingested NO-rich gel (NIT+IPC) 90min prior to testing in one trial and a low NO placebo in the other (PLA+IPC). Plasma NO and nitrite (NO) were measured immediately before and after application of IPC.

RESULTS

Plasma [NO] and [NO] were higher before and after IPC in NIT+IPC compared to BASE (P<0.001) but did not differ between BASE and PLA+IPC. There were no differences in V⋅O kinetics or muscle oxygenation parameters between trials (all P>0.4). Performance in the time-trial was similar between trials (BASE 1343±72s, PLA+IPC 1350±75s, NIT+IPC 1346±83s, P=0.98).

CONCLUSIONS

Pre-exercise IPC did not improve sub-maximal exercise or performance measures, either alone or in combination with dietary NO supplementation.