Relationships between blood viscosity and insulin-like growth factor I status in athletes

Clin Hemorheol Microcirc. 2000;22(4):277-86.


Exercise training is known (1) to enhance the function of the GH-IGF-I system, which has profound effects on body fluid status; (2) to increase blood fluidity. Thus, we investigated during an exercise-test in 39 male elite sportsmen (age 23.7+/-0.72 years; body mass index 23.7+/-0.28 kg/m2) the possible relationships between GH and IGF-I status and the rheological properties of blood. Two correlations indicate a relationship between body hydration and fitness: isometric handgrip strength is correlated with the percentage of extracellular water in total body water (r = 0.432, p = 0.02) and the aerobic working capacity W170 is negatively correlated with hematocrit (r = -0.341, p = 0.039). Water loss during exercise appears to be inversely related to fitness as evaluated by W170 (r = -0.529, p = 0.05), and is positively correlated with the score of signs of overtraining (r = 0.725, p = 0.003) and with the red blood cell aggregation index (r = 0.584, p = 0.036). Finally, while the GH peak value is correlated with the extracellular water volume (r = 0.393, p = 0.02), IGF-I is correlated with blood viscosity (r = 0.546, p = 0.0003), suggesting that when IGF-I values are within the upper quintile (>340 ng/ml) IGF-I may unfavourably affect blood rheology. Among factors of blood viscosity, IGF-I exhibits a borderline correlation (p = 0.05) with "Tk" and the ratio IGF1/IGFBP3 which reflects free circulating IGF-I is correlated with red cell aggregability measured with the Myrenne "M" (r = 0.485, p = 0.014) and S60 (r = 0.396, p = 0.494). These findings confirm the importance of hydration and dehydration as determinants of both blood rheology and exercise performance. Moreover, they suggest that values of IGF-I within the upper quintile are associated with an impairment of blood fluidity, possibly due to a direct effect of IGF-I on red cell deformability and aggregability.

MeSH terms

  • Adult
  • Blood Viscosity*
  • Body Water
  • Dehydration / blood
  • Erythrocyte Aggregation
  • Erythrocyte Deformability
  • Exercise / physiology*
  • Exercise Test
  • Hemorheology
  • Humans
  • Insulin-Like Growth Factor Binding Protein 3 / blood
  • Insulin-Like Growth Factor I / analysis*
  • Male
  • Physical Fitness
  • Sports*


  • Insulin-Like Growth Factor Binding Protein 3
  • Insulin-Like Growth Factor I