Abstract
Previously, we have found that both haemoglobin (Hb) and packed cell volume (PCV) are lowered between 24h and 72h following endurance exercise. We have subsequently monitored plasma viscosity and related indices in venous blood from 11 young males before and after a 21.1km road race.
Over the period of the race, there was a significant reduction in plasma volume (4.3 ± 6.0%, mean ± SD, p<0.05) and an increase in plasma viscosity from 1.60 ± 0.07mPa.s to 1.69 ± 0.09mPa.s (p<0.001). By 6h after the race there was an increase in plasma volume (8.4 ± 6.7%, p<0.001) still evident at 120h (10.8 ± 4.2%, p<0.001) while plasma viscosity had returned to the pre-race value by 6h post-race and remained stable in all subsequent samples. Between 6h and 120h post-race total serum protein concentrations were not significantly different from that recorded 48h before the race; serum globulin was unaltered and serum albumin slightly reduced (45.5 ± 1.5g.l−1 48h pre-race, 44.7 ± 2.0g.l−1 48h post-race, p<0.01).
We conclude that plasma viscosity remains normal despite the plasma volume expansion following endurance exercise and that this is dependent on maintenance of plasma protein concentration.
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