Myths and Facts About the Effects of Ischemic Preconditioning on Performance

Abstract

Although numerous studies have demonstrated the effect of ischemic preconditioning (IPC) in clinical application, the effectiveness of this procedure on performance and physiological variables is still debatable. Therefore a systematic review was performed, including a meta-analysis and evaluation of the quality of the papers that addressed this scope. The electronic databases of the National Library of Medicine (PubMed), Google Scholar (using [advanced search], [all fields]) and other online journals were searched, for the following descriptors: a) "ischemic preconditioning"; b) "blood flow" and "hyperemia"; c) "blood flow occlusion," combined with "exercise performance", "athletes", "exercise" and "performance". Relevant studies were included, if they conformed to strict pre-formulated criteria, excluding systematic review articles, meta-analyses and studies with only animals or non-healthy subjects. The 20 studies included had high quality scores (87%). The majority of the studies lacked statistical significance (P<0.05) for both performance and physiological variables when comparing IPC, placebo and control groups. Most studies showed that IPC has no significant influence on performance. The few studies with significant differences mainly described an improvement only in performance without altered physiological parameters. Therefore, the influence of IPC on performance is still unclear and physiologically highly debatable.

Effects of ischemic preconditioning on short-duration cycling performance

“…To reduce potential bias, subjects were all deprived from any information until the end of the data collection, and they were always verbally encouraged to realize their maximum effort. However, a placebo (and nocebo) effect cannot yet be discarded (Marocolo et al 2016). Secondly, as we employed a time window of approximately 48 h between performance visits, the extent at which the less intense second window of protection lasting 48-72 h could have affected the results is unknown (Marber et al 1993).…”

Acute ischemic preconditioning does not influence high-intensity intermittent exercise performance

“…Subjects attended the laboratory five times (with 3–5 days in-between) ( Marocolo et al, 2016a ), for initial screening and anthropometric measurements and for familiarization with the equipment and proceedings. In the 3rd, 4th and 5th visits, a randomized crossover assignment (IPC, SHAM and control) was adopted and the YoYoIE2 was carried out after 6 min of each trial (IPC, SHAM or control).…”

“…The IPC maneuver consisted of four cycles of 5-min occlusion (220 mmHg) and 5-min reperfusion (no pressure) in each thigh (total duration 40 min), using a pneumatic tourniquet (Riester Komprimeter; Riester, Jungingen, Germany) administered at the subinguinal region of the thighs. We applied this specific IPC protocol for the following reasons: (a) several studies have successfully explored the ergogenic effects of IPC on exercise performance with the same protocol ( Cruz et al, 2015 ; Jean-St-Michel et al, 2011 ; Marocolo et al, 2016a ; Patterson et al, 2015 ); (b) at least three ischemia-reperfusion cycles are necessary to protect against skeletal muscle infarction and endothelial dysfunction after prolonged periods of imposed ischemia ( Pang et al, 1995 ); and (c) it is considered safe and well tolerated in both patients and healthy volunteers ( Gonzalez et al, 2014 ). The occlusion and reperfusion phases were conducted alternately between the thighs, with subjects remaining seated (knee at 90° angle).…”

“…The effectiveness of occlusion in the IPC session was controlled by auscultation of the arteries around the ankle ( Loenneke et al, 2012 ). In the SHAM protocol, an external pressure of 20 mmHg was administered, as proposed in previous studies ( Foster et al, 2011 ; Marocolo et al, 2016a ). For the control condition, the subjects remained seated for a respective period of time.…”

“…The technique of ischemic preconditioning (IPC) alternates brief periods of occlusion and re-establishment (e.g., 3–5 min each) of muscle blood flow prior to exercise using a tourniquet applied in the proximal part of a limb (e.g., lower limbs) ( Marocolo et al, 2016a ) aiming to improve exercise performance. The ergogenic effects are still debatable ( Marocolo et al, 2016a ) especially because some study designs are limited (e.g., without placebo-control) ( Da Mota & Marocolo, 2016 ) and the mechanism behind IPC as well as its supposed exercise enhancement has yet to be clarified. Potential mechanisms of IPC exercise enhancement are hyperemia (5–6 fold increase in muscle blood flow) during reperfusion ( Libonati et al, 2001 ), attenuated ATP depletion, and increased phosphocreatine production/oxygen uptake during the reperfusion phase ( Andreas et al, 2011 ).…”