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OBJECTIVE: Blood volume (BV) and hemoglobin concentration (Hb) play important roles in oxygen transport. Manipulation of both BV and Hb can markedly affect systemic oxygen transport and maximal aerobic capacity (VO2max). However, the role of BV in oxygen transport and aerobic performance is not well understood. It has recently been postulated that an acute expansion of BV using plasma volume (PV), independent of changes in Hb, may represent a potential ergogenic property. Therefore, the primary objective of this review was to determine the potential ergogenic properties of volume loading. DATA SOURCES: An extensive research of Medline and Sport-Discus along with cross-referencing was conducted. Articles were included on the basis of their relevancy to the purpose of this review. Only articles published in English were included in the analysis. STUDY SELECTION: All study designs using human participants were reviewed. DATA EXTRACTION: A systematic analysis of data regarding the effect of BV on the determination of oxygen transport, aerobic capacity, and endurance performance was conducted. Particular emphasis was given to articles that examined BV as the key independent variable. Articles relevant to the evaluation of the impact of BV on aerobic capacity and endurance performance were reviewed according to the strengths of the individual study designs. RESULTS: Seven investigations evaluated the impact of acute changes in BV, independent of changes in Hb, on VO2max. Of these investigations, three revealed that acute manipulations of BV result in no change or a slight reduction in VO2max. Three investigations revealed a significant improvement in VO2max after acute PV expansion. One investigation revealed a nonsignificant increase in VO2max after acute PV expansion. Seven investigations evaluated the impact of acute changes in BV, independent of changes in Hb, on endurance performance: two revealed a significant improvement in endurance performance after acute PV expansion, and five revealed an unchanged or reduced endurance performance after acute PV expansion. The majority of investigations showing an improvement in VO2max and/or endurance performance after acute PV expansion were conducted using untrained individuals. CONCLUSION: Volume loading does not result in an improvement in VO2max and/or endurance performance in endurance athletes. Volume loading in untrained individuals may improve VO2max, but does not bring these individuals to the aerobic capacity of endurance-trained athletes. Also, volume loading generally does not lead to improvement in endurance performance, irrespective of its effects on VO2max.
Warburton et al. (Sat,) studied this question.