The impact of 5 consecutive days of ischemic preconditioning on running performance in hypoxia

Brief periods (~ 5 min) of occlusion followed by reperfusion, otherwise known as ischemic preconditioning (IPC), induce local effects that protect the myocardium from ischemic injury (Murry, Jennings & Reimer, 1986). IPC has also been show to improve exercise performance (Bailey et al., 2012; Barbosa et al., 2015; Crisafulli et al., 2011; de Groot, Thijssen, Sanchez, Ellenkamp & Hopman, 2010; Foster, Giri, Rogers, Larson & Anholm, 2014; Jean-St-Michel et al., 2011; Kjeld, Rasmussen, Jattu, Nielsen & Secher, 2013). The proposed mechanisms are thought to be attributed to the vasculature, triggering an increase in blood flow (Shimizu, Konstantinova, Kharbanda, Cheung & Redington, 2007) and oxygen delivery to the working muscles (Saito, Komiyama, Aramoto, Miyata & Shigematsu, 2004). A natural physiological response to altitude exposure (≥ 1500 m) is hypoxic pulmonary vasoconstriction (HPV), which reduces blood flow and oxygen delivery to the exercising muscles (Wyatt, 2014). Therefore, it appears possible that IPC may enhance performance in hypoxia however, this has not been found after a single bout of IPC (Foster, Westerdahl, Foster, Hsu & Anholm, 2011 & Hittinger et al., 2015). Multiple bouts of IPC significantly increase flow mediated dilution (FMD) (Jones et al., 2014 & Jones et al., 2015), and thus chronic IPC may enhance performance in hypoxia.