Figure 2
From: Measuring the Energy of Ventilation and Circulation during Human Walking using Induced Hypoxia

Changes in ΔEE versus in ΔVE (top panel), and changes in ΔEE versus in ΔHR (middle panel). Ordinary least squares linear regression equations, with intercept = 0, are shown. Changes in ΔVE versus in ΔHR (bottom panel). Second order polynomial regression equation, with intercept = 0, are shown.