Body Pod.......Yep I know a sports med doctor who has one, and he claims it as accurate as hydro ?? I went in 3 week ago and will be going next monday to see my progress.
The bod-pod is almost as accurate as hydrostatic. It uses the same principles. It measures the displacement of the air inside the "pod" just as the hydrostatic measures the displacement of the H20.
D= m/v
They know your mass, find your volume, and then calculate density. They use calculations and variables based on race, sex, ect to find BF.