Ischemic preconditioning at moderate and high pressures does not attenuate muscle fatigue

The purpose of this investigation was to examine muscle fatigue following ischemic preconditioning (IPC). Sixteen males randomly completed three cycles of IPC at a low absolute (20 mmHg [IPC_SHAM]), moderate individualized (80% of total arterial occlusion pressure [IPC₈₀]), and high absolute (220 mmHg [IPC₂₂₀]) pressure, with each cycle consisting of five minutes followed by five minutes of zero pressure. Following IPC, participants performed one-set to failure of unilateral, isotonic, concentric-only leg extension muscle actions at 30% of one-repetition maximum. Prior to and following the exercise protocol, participants completed maximal voluntary isometric contractions (MVIC's) with motor nerve stimulation. Separate two-way, 3 (Pressure [IPC_SHAM, IPC₈₀, and IPC₂₂₀])×2 (Time [Pretest, Posttest]), repeated-measures ANOVAs were constructed to assess MVIC, peak twitch torque (PTT), voluntary activation (VA), and surface electromyographic amplitude (sEMG_AMP). There were no significant interactions or main effects of Pressure. There were, however, significant main effects of Time for MVIC (- 48.7 Nm; g=0.58), PTT (- 29.4 Nm; g=0.82), VA (- 7.3%; g=1.09), and sEMG_AMP (+1.7%; g=0.95). IPC at a moderate individualized and high absolute pressure did not facilitate attenuations in muscle fatigue. The decreases across time may reflect that muscle fatigue was peripheral in origin.