Ischemic Conditioning to Reduce Fatigue in Isometric Skeletal Muscle Contraction

Simple Summary Ischemic preconditioning (IPC) is a protective maneuver that alternates short periods of occlusion and reperfusion of tissue blood flow. Nineteen subjects were enrolled in one of the two groups, IPC (3 x 5/5 min right arm ischemia/reperfusion; cuff inflations 250 mmHg) and SHAM (3 x 5/5 min pseudo ischemia/reperfusion; 20 mmHg). The subjects performed a fatiguing contraction protocol before and 30 min after the IPC treatment. Results suggest that IPC may delay fatigue onset by reducing muscle oxygen consumption. The decrease in tissue oxygenation and the increase in deoxygenated hemoglobin were significantly reduced post- vs. pre-IPC (p < 0.05), but not post- vs. pre-SHAM. IPC delays the onset of fatigue, probably due to improved metabolic efficiency of muscles. Ischemic preconditioning (IPC) is a non-invasive protective maneuver that alternates short periods of occlusion and reperfusion of tissue blood flow. Given the heterogeneity in the magnitude and frequency of IPC-induced improvements in physical performance, here we aimed to investigate, in a well-controlled experimental set-up, the local effects of IPC in exposed muscles in terms of tissue oxygenation and muscle fatigue. Nineteen subjects were enrolled in one of the two groups, IPC (3 x 5/5 min right arm ischemia/reperfusion; cuff inflations 250 mmHg) and SHAM (3 x 5/5 min pseudo ischemia/reperfusion; 20 mmHg). The subjects performed a fatiguing contraction protocol before and 30 min after the IPC treatment, consisting of unilateral intermittent isometric elbow flexions (3 s ON/OFF, 80% of maximal voluntary contraction) until exhaustion. While muscle strength did not differ between groups, post- vs. pre-treatment endurance was significantly reduced in the SHAM group (4.1 +/- 1.9 vs. 6.4 +/- 3.1 repetitions until exhaustion, p < 0.05) but maintained in IPC (7.3 +/- 2.0 vs. 7.1 +/- 4.3, n.s.). The decrease in tissue oxygenation and the increase in deoxygenated hemoglobin were significantly reduced post- vs. pre-IPC (p < 0.05), but not post- vs. pre-SHAM. The results suggest that IPC delays the onset of fatigue likely through improved metabolic efficiency of muscles.