Effect of Plasma Volume Loss during Graded Exercise Testing on Blood Lactate Concentration

The Journal of Physiological Sciences

James A. Davis¹  Michael T. Carizzi¹  Patrick H. Pham¹  Derek M. DeCicco¹  Ralph Rozenek¹ 

[1] Laboratory of Applied Physiology, Department of Kinesiology, California State University/Long Beach

关键词: cycle ergometer;    graded exercise testing;    hemoconcentration;    lactate threshold;    onset of blood lactate accumulation;   

DOI  :  10.2170/physiolsci.RP014406

学科分类：生理学

来源: Springer

【 摘 要 】

References(29)Cited-By(1)Previous studies have shown that plasma volume (PV) loss can be a confounding variable in the interpretation of changes in blood constituents. We examined the effect of PV loss on three features of the blood lactate versus work-rate relationship, namely, slight blood lactate increase during the early stages of graded exercise testing (GXT); work rate at the onset of a systematic increase in blood lactate, i.e., lactate threshold (LT); and work rate at a blood lactate concentration of 4 mM, i.e., onset of blood lactate accumulation (OBLA). Fourteen subjects underwent cycle ergometer GXT. Blood samples were obtained at rest and at the end of each 3-min work-rate increment and analyzed for hematocrit and lactate concentration. For exercise levels up to and including LT, PV loss was relatively stable at approximately 2.8%. Beyond LT, PV loss accelerated. From the first work rate to LT, blood lactate concentration uncorrected for PV loss increased 0.24 ± 0.07 mM (P < 0.05). After correction for PV loss, the increase was 0.21 ± 0.08 mM (P < 0.05). These mean increases were not significantly different from each other. For the four exercise levels above LT common to most subjects, PV-corrected lactate values were significantly lower than uncorrected values. Correction of lactate values for PV loss did not alter LT for any subject, but it did result in a significant increase in OBLA. Thus, PV loss has the potential to be a confounding variable for the interpretation of blood lactate parameters that are determined at exercise levels above LT.

【 授权许可】

Unknown