Ischemic Preconditioning, O2 Kinetics, and Performance in Normoxia and Hypoxia

Introduction Ischemic preconditioning (IPC) before exercise has been shown to be a novel approach to improve performance in different exercise modes in normoxia (NORM). Few studies have been conducted examining potential mechanisms behind these improvements, and less has been done examining its influence during exercise in hypoxia (HYP). Oxygen uptake and extraction kinetics are factors that have been implicated as possible determinants of cycling performance. We hypothesized that IPC would lead to improvements in oxygen extraction and peripheral blood flow kinetics, and this would translate to improvements in cycling time trial (TT) performance in both NORM and HYP. Methods Thirteen men (age, 24 ± 7 yr; V˙O2max, 63.1 ± 5.1 mL·kg−1·min−1) participated in the study. Subjects completed trials of each combination of normobaric HYP (FiO2 = 0.16, simulating ~8000 ft/2500 m) or NORM (FiO2 = 0.21) with preexercise IPC protocol (4 × 5 min at 220 mm Hg) or SHAM procedure. Trials included submaximal constant load cycle exercise bouts (power outputs of 15% below gas exchange threshold, and 85% of V˙O2max), and a 5-km cycling performance TT. Results Ischemic preconditioning significantly improved 5-km TT time in NORM by 0.9% ± 1.8% compared with SHAM (IPC, 491.2 ± 35.2 s vs SHAM, 495.9 ± 36.0 s; P
Source: Medicine and Science in Sports and Exercise - Category: Sports Medicine Tags: APPLIED SCIENCES Source Type: research