Physical activity has been shown to reduce blood viscosity (Carroll et al. 2000). Brun et al. (1998) observed that the immediate effect of exercise is an increase in blood viscosity resulting from fluid shifts; however, in the long-term, exercise reduces and improves blood viscosity. Exercise was shown to improve blood chemistry profiles (lipid and fibrinogen). Brun et al. concluded that the effect of exercise on blood viscosity suggests that viscosity can act as a marker of cardiovascular risk reversal and that blood viscosity directly influences physical fitness. 

A long-term regimen of physical exercise decreases blood viscosity, decreases systolic and diastolic blood pressure, and helps inhibit the progression of cardiovascular disease if the exercise is taking place with a heart that is functioning efficiently. If exercising with an inefficiently functioning heart, a patient may only be accelerating the disease process. 

The effects of exercise on blood viscosity have been studied extensively: 

-El Sayed (1998) reported that endurance training may result in better delivery of oxygen to muscles because of the dilutional effect on the blood. 

-Brun (2002) observed that exercise in patients with metabolic or cardiovascular disease had better blood viscosity and physical fitness. 

-In a study of elite athletes, Monnier and colleagues (2000) confirmed positive relationships between hydration, blood viscosity, and fitness. 

-Ernst and Matrai (1987) gave regular, standardized treadmill exercise for 2 months to 42 stable patients with leg pain (claudication which results from PAD). They observed that blood viscosity and other hemodynamic parameters normalized to the same level as healthy people over 2 months. 

Elevated whole blood viscosity should be corrected before engaging in intense exercise regimens.


1. Carroll S, Cooke CB, Butterly RJ. Physical activity, cardiorespiratory fitness, and the primary components of blood viscosity. Med Sci Sports Exerc 2000;32:353-358. 

2. Brun JF, Khaled S, Raynaud E, et al. The triphasic effects of exercise on blood rheology: which relevance to physiology and pathophysiology? Clin Hemorheol Microcirc 1998;19:89-104. 

3. El Sayed MS. Effects of exercise and training on blood rheology. Sports Med 1998;26:281-292. 

4. Brun JF. Exercise hemorheology as a three acts play with metabolic actors: is it of clinical relevance? Clin Hemorheol Microcirc 2002;26:155-174. 

5. Ernst EE, Matrai A. Intermittent claudication, exercise, and blood rheology. Circulation 1987;76:1110-1114.

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