Ischemic preconditioning: exploring local ergogenic mechanisms in non-fatiguing voluntary contractions

Abstract

Background: IPC has been suggested to boost skeletal muscle performance, though its effectiveness remains controversial. This study evaluates whether IPC influences local hemodynamic responses and surface electromyographic (sEMG) activity during non-fatiguing voluntary sustained and intermittent contractions. Methods: Ten male participants were subjected to IPC (3 cycles, 5-min ON/5-min OFF right arm ischemia, cuff pressure: 250 mmHg) and SHAM (same protocol at 20 mmHg) in two different sessions. Near-infrared spectroscopy was used to monitor tissue oxygenation (TOI) and deoxy-hemoglobin (HHb) in extensor and flexor forearm muscles. sEMG was also recorded. Measurements were taken during sustained (20-s duration) and intermittent (5 s ON/5 s OFF) isometric contractions at 20, 30, and 40% of the maximal voluntary contraction. These non-fatiguing exercise tasks were performed before and 30 min after the IPC/SHAM intervention. Results: sEMG exhibited a significant increase post vs. pre-treatment in both IPC and SHAM in extensors. A significant decrease in TOI at rest was noted pre vs. post-treatment for both IPC and SHAM (p < 0.01). In general, no main effect of treatment was observed, except for HHb changes during contraction in extensor muscles, associated with no effect of time and no time-treatment interaction. All variables exhibited a main effect of force level (p < 0.05), with no interaction with treatment or time. Conclusion: IPC had no effect on hemodynamic and electromyographic variables during sustained and intermittent handgrip. These results do not support IPC-related ergogenic effects at the muscle level, aligning with previous findings on electrically stimulated contractions.