Anemia causes a relative decrease in blood lactate concentration during exercise

Summary

The purpose of the present study was to examine to what degree a reduction in systemic oxygen transport capacity influences the absolute and relative levels (% of maximal oxygen uptake) of submaximal blood lactate accumulation. Anemia was induced by repeated venesections in eight healthy males. After 9–10 weeks of anemia, hemoglobin concentration [Hb] was restored by retransfusion of packed erythrocytes. The [Hb] values obtained were, before venesections, in control (C)=145±10, in the anemic state (A)=110±8, and after retransfusion (R)=143+-8 g · l⁻¹ respectively. In all states, muscle biopsies were taken and measurements made of $V_{O_{2{\text{max}}} }$ and $V_{{\text{O}}_{\text{2}} }$ at a running velocity corresponding to a blood lactate concentration of 4 mM (v _{Hla 4.0}). In the A condition $V_{O_{2{\text{max}}} }$ decreased by 19% as compared to C (P<0.01). v _{Hla 4.0}. v _{Hla 4.0} was 14% lower in A as compared to C and R (p<0.01). $V_{{\text{O}}_{\text{2}} }$ at v _{Hla 4.0} was 13% lower in A as compared to C (P<0.01). However, $V_{{\text{O}}_{\text{2}} }$ at v _{Hla 4.0} expressed as a percentage of $V_{O_{2{\text{max}}} }$ was increased (P<0.01) in the anemic state, the values obtained being C=83.3%, A=89.8% and R=84.8%. Ventilation at v _{Hla 4.0} was higher in A as compared to C and R (P<0.05). R and C values were not significantly different for any of the values presented above. The maximal activity of citrate synthase in muscle did not differ between the three different conditions. It is concluded that a reduction in systemic oxygen transport leads to an absolute decrease in the fixed anaerobic threshold. However, peripheral factors modified this decrease. As a consequence there was a marked shift to the right, relative to $V_{O_{2{\text{max}}} }$, in the submaximal lactate accumulation upon induction of anemia.