Blood volume, aerobic power, and endurance performance: Potential ergogenic effect of volume loading

Objective: Blood volume (BV) and hemoglobin concentration ([Hb]) play impor tant roles in oxygen transport. Manipulation of both BV and [Hb] can marked ly affect systemic oxygen transport and maximal aerobic capacity ((V) over dot O(2)max). However, the role of BV in oxygen transport and aerobic perfo rmance is not well understood. It has recently been postulated that an acut e expansion of BV using plasma volume (PV), independent of changes in [Hb], may represent a potential ergogenic property. Therefore, the primary objec tive 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 the ir relevancy to the purpose of this review. Only articles published in Engl ish 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 o n the determination of oxygen transport, aerobic capacity, and endurance pe rformance was conducted. Particular emphasis was given to articles that exa mined BV as the key independent variable. Articles relevant to the evaluati on of the impact of BV on aerobic capacity and endurance performance were r eviewed 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 (V) over dot O(2)max. Of these investiga tions, three revealed that acute manipulations of BV result in no change or a slight reduction in (V) over dot O(2)max. Three investigations revealed a significant improvement in (V) over dot O(2)max after acute PV expansion. One investigation revealed a nonsignificant increase in (V) over dot O(2)m ax after acute PV expansion. Seven investigations evaluated the impact of a cute changes in BV, independent of changes in [Hb], on endurance performanc e: two revealed a significant improvement in endurance performance after ac ute PV expansion, and five revealed an unchanged or reduced endurance perfo rmance after acute PV expansion. The majority of investigations showing an improvement in (V) over dot O(2)max and/or endurance performance after acut e PV expansion were conducted using untrained individuals. Conclusion: Volume loading does not result in an improvement in (V) over do t O(2)max and/or endurance performance in endurance athletes. Volume loadin g in untrained individuals may improve (V) over dot O(2)max, but does not b ring these individuals to the aerobic capacity of endurance-trained athlete s. Also, volume loading generally does not lead to improvement in endurance performance, irrespective of its effects on (V) over dot O(2)max.