Which body composition method requires the participant to submerge in water?

The method that requires the participant to submerge in water is hydrostatic weighing. This technique is based on the principle of buoyancy and uses the water displacement to determine body density. When a person is submerged, the volume of water displaced is measured, which, when combined with body weight measured outside the water, helps to calculate body fat percentage. This method is considered one of the most accurate for determining body composition because it accounts for the density differences between fat and lean tissue effectively.

In contrast to hydrostatic weighing, bioelectrical impedance analysis measures body composition by sending a weak electrical current through the body to assess resistance and reactance, while skinfold calipers estimate body fat by pinching the skin at various sites to measure subcutaneous fat thickness. Air displacement plethysmography, like hydrostatic weighing, is also a method for determining body volume but uses air rather than water to measure body density. Each of these methods has its own approach, but hydrostatic weighing specifically requires submersion, making it unique among the options provided.