A model for identifying intensity zones above critical velocity

Abstract

Bergstrom, HC, Housh, TJ, Cochrane-Snyman, KC, Jenkins, NDM, Byrd, MT, Switalla, JR, Schmidt, RJ, and Johnson, GO. A model for identifying intensity zones above critical velocity. J Strength Cond Res 31(12): 3260–3265, 2017—The purpose of this study was to describe the V_ O2 responses relative to V_ O2peak at 4 different intensities within the severe domain and, based on the V_ O2 responses, identify intensity zones above critical velocity (CV). Twelve runners (mean 6 SD age = 23.2 6 3.0 years) performed an incremental treadmill test (ITT) to exhaustion to determine the V_ O2peak and velocity associated with V_ O2peak (vV_ O2peak). Critical velocity was determined from 4 exhaustive, constant velocity, randomly ordered treadmill runs (V1, V2, V3, and V4; V1 = highest, V4 = lowest). The V_ O2 responses were recorded during each of the constant velocity runs. Mean differences among V_ O2peak values from the ITT and the highest value recorded during the constant velocity runs were examined. The V_ O2 values at exhaustion for V1 (3.32 6 0.10 L$min21, p = 0.15) and V2 (3.27 6 0.91 L$min21, p = 0.13) were not significantly different from V_ O2peak (3.39 6 0.96 L$min21) from the ITT. The V_ O2 values at exhaustion for V3 (3.18 6 0.88 L$min21; p = 0.007) and V4 (3.09 6 0.86 L$min21; p = 0.003), however, were significantly less than the V_ O2peak from the ITT. There were intensity-dependent V_ O2 responses above CV. Based on these findings, we have hypothesized 3 intensity zones (first severe intensity zone [SIZ1], second severe intensity zone [SIZ2], and extreme intensity zone [EIZ]) within the severe and extreme domains, which are characterized by specific V_ O2 responses and may be used to design programs that maximize aerobic performance adaptations.