Abstract

Background: High-intensity interval training is traditionally prescribed using fixed values that may be insufficient to generate homeostatic disturbances. Objective: To evaluate how a high-intensity interval training program, guided by parasympathetic activity, affects the cardiorespiratory capacity of physically active university students. Method: Controlled, parallel and randomized study with single blinding. 26 physically active university students were divided into a control group and an experimental group to undergo 4 weeks of high-intensity interval training. Cardiorespiratory capacity was estimated using the 3x1 Step Test and heart rate variability was determined using an orthostatic test Results: Both groups showed significant changes in peak VO2, with the experimental group showing greater improvement (C.V = 14%; p = 0.003; d = 1.16) compared to the control group (C.V = 11%; p = 0.01; d = 0.7). Regarding parasympathetic activity, only the experimental group showed significant changes in heart rate (C.V = 10.5%; p = 0.004; d = 1.28) and root mean square of successive differences (C.V = 19.7 %; p = 0.02; d = 1.16) in the supine position. Conclusion: A high-intensity, high-volume, short-duration interval training prescribed based on parasympathetic activity can be an effective stimulus to improve cardiorespiratory fitness in physically active university students.