Effects of ischemic preconditioning on indirect markers of exercise-induced muscle damage: protocol for a randomized placebo-controlled trial

Background: Ischemic preconditioning (IPC) has been used to improve exercise performance, but its role in protecting against exercise-induced muscle damage (EIMD) is still unclear. Objective: To investigate the effects of IPC on the indirect markers of EIMD when compared to placebo. Methods: 30 healthy young men, with no recent experience in lower limb strength training, will be recruited. Subjects will be allocated randomly into two groups: IPC or placebo. The IPC group will undergo 4 x 5 min of occlusion (with individualized total occlusion pressure), interspersed with 5 min of reperfusion. The placebo group will be submitted to the same protocol, but with minimum pressure (10mmHg) being applied during the occlusion period. After the interventions, volunteers will be submitted to muscle damage induced by isokinetic exercise (10 sets of 12 maximum eccentric repetitions) in the non-dominant femoral quadriceps. The primary outcome will be isometric peak torque, measured both before and up to 72 hours after exercise. Secondary outcomes include rate of torque development, muscle soreness, knee range of motion, thigh circumference and blood levels of creatine kinase. Discussion: The results of this trial will indicate whether the effects of IPC are superior to placebo in the protection against EIMD.