Conventional wisdom suggests that strength training increases body mass index (BMI) in a positive way, but does it? BMI is a simplistic measure of body fat. It is calculated by dividing one’s weight in kilograms by the square of one’s height in meters. The derived results can then be compared to a chart of normative data provided by the National Institutes of Health (NIH). BMI is useful for the overweight and obese, yet it does have limitations. BMI may overestimate body fat in athletes and others who have muscular builds. The problem is this simple tool does not differentiate between fat mass and lean body mass. It has long been argued that heavily muscled, weight-trained athletes are healthy despite their BMI classification.

At issue is the athlete that increases muscle mass and vascularity significantly in all areas of the body but the neck region alters peripheral vascular resistance in an acute way. Peripheral resistance is a function of the internal vessel diameter, vessel length and blood viscosity. Having a large body and an undeveloped neck changes the force of the delivery system’s blood flow to the head.