Acute effects of ischemic preconditioning on maximal strength and neuromuscular function.

PURPOSE: To examine the acute effects of ischemic preconditioning (IPC) implemented at a low (20 mmHg [IPCSHAM]), moderate (80% of total arterial occlusion pressure [TAOP]; [IPC80]), and high (220 mmHg [IPC220]) pressure prior to an acute bout of fatiguing resistance exercise. METHODS: Ten females randomly completed IPC on separate visits at a low, moderate, and high pressure across three cycles, where one cycle consisted of five minutes at the assigned pressure followed by five minutes of no pressure. Following IPC, participants performed one-set to volitional failure of unilateral, isotonic, concentric-only leg extension muscle actions at 30% of one-repetition maximum. Concentric peak torque (CPT) and maximal voluntary isometric contractions (MVIC) were performed prior to and immediately following the bout of exercise, while surface electromyography (sEMG) was recorded continuously. All dependent variables were analyzed with Bayesian multilevel models. RESULTS: Total repetitions completed were 61.7 ± 38.9, 59.2 ± 33.8, and 58.4 ± 19.8 repetitions for IPCSHAM, IPC80, and IPC220, respectively. CPT and MVIC decreased from pretest to posttest (Mean difference [Meandiff] = 48.5 ± 0.9 Nm and 23.0 ± 0.4 Nm, respectively). From the first five to the last five repetitions, sEMG amplitude (Meandiff = -114.0 ± -16.0%) increased, while sEMG mean power frequency (Meandiff = 21.9 ± -0.6%) and neuromuscular efficiency (i.e., Nm:µV) (Meandiff = 0.18 ± 0.01 Nm:µV) decreased. CONCLUSION: Applying IPC did not exhibit an ergogenic effect on maximal strength, nor did it delay the onset of muscle fatigue. These findings suggested that IPC does not attenuate the typical fatigue-induced responses of acute resistance exercise.