Figure 3.

Exercise ${\dot{V}}_{\mathbf{E}}/\mathbf{HR}$relationship in all subjects. Exercise ${\dot{V}}_{\mathrm{E}}/\mathrm{HR}$ response in the six subjects studied at SL (circle) and at HA (square)at free will (empty symbol) and with effort (filled symbol). The black arrow indicates VCP; the white arrow indicates the θ_L (see text for further comments).