A study published ahead of print in the British Journal of Sports Medicine finds that fatness increases the level of inflammatory activity in the body as measured by white blood cell counts. Researchers also found that levels of inflammatory activity are lower in people who are more physically fit.

Neil M. Johannsen (Pennington Biomedical Research Center, United States) and colleagues studied 452 healthy men who participated in the Aerobics Center Longitudinal Study. The researchers measured levels of different groups of white blood cells (neutrophils, lymphocytes, monocytes, basophils, and eosinophils) during exercise and analyzed their relationships to body fat and physical fitness. In addition to providing blood samples and blood pressure measurements, participants were weighed and measured. None of the participants was a smoker, and none had been previously diagnosed with a serious disease or long term condition that may affect higher white blood cell counts.

The researchers found that, after controlling for age, men who were most physically fit had the lowest levels of groups of white blood cells. Combining the groups of white blood cells created a measure of total white blood cell count, which is used as a marker for inflammatory activity. High total white blood cell counts have also been associated with illness and death from coronary heart disease. High levels of white blood cells were associated with higher levels of body fat as measured by body-mass index (BMI).

Men who had both high levels of body fat and low levels of physical fitness had the highest total white cell count and highest levels of neutrophils, lymphocytes, and basophils groups. High white cell count levels were also associated with men with lower body weight and lower levels of fitness. The researchers note that the effect of extra body fat on white blood cell count could be negated by a high degree of physical fitness.

According to the authors, regular exercise may train the body to respond more efficiently to physical demands even though vigorous exercise tends to raise white cell counts.

Association of White Blood Cell Subfraction Concentration with Fitness and Fatness
Neil M. Johannsen, Elisa L. Priest, Vishwa D. Dixit, Conrad P. Earnest, Steven N. Blair, and Timothy S. Church
British Journal of Sports Medicine (2008).
doi 10.1136/bjsm.2008.050682
Click Here to View Abstract


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