Figure 2.

Representative subject #1 (male, 36 years). Exercise response variables in a representative subject at SL (empty circle) and at HA (filled circle). The black arrow indicates VCP; the white arrow indicates the θ_L. In this subject, a second and less evident breakpoint ${\dot{V}}_{\mathrm{E}}/\mathrm{HR}$ that occurred at the HR value observed at θ_L was identifiable (see text for further comments).