One of the most "hot" scientific research in medical and sports dress is the identification of an index of physical fitness related to body weight. Obviously, this index has a different value depending on the science that studies the fact, while in the medical field, this should indicate a state of well-being of the subject, with particular reference to obesity or excessive thinness, situations, both considered harmful to human health; in sports this index has different value and should indicate a situation optimal for achieving high performance.

Obviously, then, the two values are different between them, as different are the aims that this index is to be reached: physical well-being first, best performance of the other. Over the years, several researchers have developed a set of formulas, which have found more or less successful, not because of the professionalism of those who had developed, but to the objective difficulty of establishing a unique measurement meters. One of the first formula used was the formula Bernhardt, much in use up to 50 years ago. This considered the ideal weight of a person that you value by multiplying the body height in cm with a chest circumference and then dividing by 240.

Bernhardt formula: ideal weight in kg = height in cm X chest circumference in cm / 240

This formula, although in its validity does not take into account the subject's age, his sex, a key element, and obviously does not take into account any sporting activity of the subject. It was later used Broca formula, still used by many, that includes a demonstration of ideal weight by body height in cm - 100