Numerous clinical studies have already demonstrated that a long-term regimen of physical exercise decreases viscosity, as well as systolic and diastolic blood pressure. Exercise helps inhibit the progression of cardiovascular disease if driven by an efficiently functioning heart.

  • Endurance training has been shown to result in better delivery of oxygen to muscles by lowering blood viscosity [1].
  • A study of elite athletes demonstrated positive relationships between hydration, blood viscosity, and fitness [2].

What is less well-known is that dividing the proportion of blood cells (hematocrit) of an athlete’s blood by viscosity (i.e., Hct / BV) provides a key index for circulatory efficiency—the oxygen delivery index.

Controlling blood viscosity reduces traffic in the blood vessels and aerobic fatigue. The oxygen delivery index provides a way for athletes to monitor how much oxygen their blood can actually deliver, not just how much oxygen the blood can carry.


  1. El Sayed MS. Effects of exercise and training on blood rheology. Sports Med 1998; 26:281-92.
  2. Monnier JF, Benhaddad AA, Micallef JP, et al. Relationships between blood viscosity and insulin-like growth factor I status in athletes. Clin Hemorheol Microcirc 2000; 22:277-86.