Effects of ischemic preconditioning on exercise economy

Ischemic preconditioning (IPC) is the application of small bouts of ischemia followed by reperfusion. IPC has shown to improve exercise performance in a number of studies related to swimming, cycling and 5 K running. However, effect of ischemic preconditioning on running economy have not be investigated so far. We proposed that bilateral remote ischemic preconditioning will improve running economy in young healthy people. Methods: The study was a randomized single- blinded crossover study. Nineteen young men and women were included in the study. Each participant underwent a sham and IPC trial using high pressure cuff (EC20 rapid cuff inflator, DE Hokanson, Inc.) followed by running economy trial (Parvo Medics, TrueOne 2400) of 15 minutes. The sham or IPC trial consisted of 3X 5 min of bilateral leg ischemic at pressure of 15 mm of Hg to 220 mm of Hg. Each 5 min stage of bilateral leg ischemia was followed by 5 minutes of reperfusion which was followed by 3X 5 min of submaximal treadmill running. Results The data was completed and analyzed for 18 subjects. The mean age of participants was 27+7 years with BMI for all subjects was 24.6+/- 3.0 kg/m2. A two way ANOVA was used to assess interaction in running economy (i.e., steady-state oxygen consumption, respiratory exchange ratio, heart rate) in the absence and presence of IPC. In the sham running trial, oxygen consumption progressively increased 22% (P<0.001) from 34.1 (stage 1) to 41.6 ml/kg/min (stage 3) and 20% (P<0.001) from 34.3 (stage 1) to 41.4 ml/kg/min (stage 3) in the IPC running trial. There was no time X trial interaction in steady-state oxygen. Running economy showed no significant change during the sham running trial, (P=0.232) from 201.6 (stage 1) to 204.0 ml/kg/km (stage 3). The same trend in running economy was observed during the IPC trial (P=0.129; from 202.8 to 203.1 ml/kg/km). There was no time X trial interaction (P=0.647) in running economy. Additionally heart rate showed a general increase from 152+/-9 (stage 1) to174+/-6 (stage 3) for the sham trials and 151+/-11 to 174+/-8 for IPC trials. We did not find significant differences in heart rate during sham and IPC trials (P= 0.999). Conclusion. The present study did not supported our hypothesis that remote IPC can improve running economy.