Are The Effects Of Ischemic Preconditioning On Fatigue Performance Testing Influenced By The Applied Pressure?

Research on ischemic preconditioning (IPC) and performance has been equivocal. The use of an arbitrary pressure in those studies may have subjected some, but not all individuals to degrees of ischemia that were sufficient for eliciting benefits. Applying pressure relative to the arterial occlusion pressure (% AOP) may facilitate a more uniform stimulus. If a higher pressure results in differences in performance, then something other than blood flow restriction may be driving the response. PURPOSE: To examine the effects of IPC on performance and pressure pain threshold (PPT). METHODS: 24 participants (18-35 yrs) completed 5 visits. After familiarization, participants were randomized to perform 4 separate protocols: 1) 110% AOP; 2) 150% AOP; 3) 10% AOP (Sham); 4) time-matched control. Each IPC protocol consisted of 4 cycles of 5 min occlusion followed by 5 min reperfusion (40 total min) on the dominant arm, after which 2 sets of 75 s maximal unilateral elbow flexion isokinetic dynamometry (240°/s angular velocity) were performed. Total work and peak torque were assessed as markers of performance. PPT of the forearm was measured before and prior to the performance measure. A Bayesian repeated measures ANOVA was used to determine differences between conditions. Data are presented as median difference (95% credible interval) or mean (SE). RESULTS: PPT increased following IPC (BF10: 4959). Both 110% AOP and 150% AOP resulted in similar increases relative to the control [110%: difference of 0.35 (0.18, 0.51) kg/cm2; 150%: difference of 0.47 (0.21, 0.73) kg/cm2] and sham [110%: difference of 0.32 (0.16, 0.48) kg/cm2; 150%: difference of 0.45 (0.17, 0.72) kg/cm2]. There were no differences between control and sham (BF10: 0.23). For performance, there were no differences between conditions for total work (BF10: 0.08), however, there was a main effect of time. The total work completed in the first set was 3398 (207) J, and in the second set, 2539 (133) J. Peak torque was not different between conditions (BF10: 0.10), however, there was a main effect of time. Peak torque in the first set was 40 (2.2) Nm and 34(1.6) Nm in the second set. CONCLUSION: The application of pressures greater than arterial occlusion increased PPT to a greater extent than a sham pressure; however, the increased PPT was not accompanied by increased performance.