A triathlete's body is his best asset in winning races. The triathlon is a demanding sport for training and races, so having the right body composition can be the difference between finishing first or last. Body fat plays an important role in energy production, but too much can hinder performance.

Body Composition

The human body is made up of two different types of mass--lean and fat. Fat mass refers to tissue stored as excess fat, and lean mass is the rest of the body, such as organs, muscles and bones. Two people can have the same body weight but their body composition may differ significantly. For example, two people can weigh 190 pounds, with one tall and one short. The shorter athlete would have a higher fat mass. The average male should have body fat of 12 percent to 18 percent, and for women, it is 22 percent to 28 percent.

Bioelectrical Impedance Spectroscopy

There are a variety of ways to measure a triathlete's body-fat percentage. The two most common are bioelectrical impedance spectroscopy (BIS) and skin calipers. The BIS method involves inputting age, weight and gender details into a handheld machine, then holding onto pads as an electrical current passes through the body. It measures the conductivity of the body as the electrical impulse travels freely through muscle and water but not through fat mass. The higher the resistance, the higher the fat-percentage reading.

Skin Calipers

Skin caliper testing involves using a set of calipers that pinch sections of the skin and fat and measure the amount in millimeters. There are four sites taken: biceps, triceps, subscapularis (shoulder blade) and suprailiac (hip). The results from each are put into an equation that gives you an overall body-fat percentage, though this is difficult as only trained professionals are usually able to grab purely fat and skin and not muscle tissue.

Importance of Body-Fat Percentage

The correct percentage of body fat for a triathlete should be 5 percent to 12 percent in males and 10 percent to 15 percent in women. Triathletes require a low level of body fat because any excess weight will cause a strain during a race. During the running or cycling stages, excess weight means having to work harder and expending more energy. Body fat is more buoyant than muscle tissue, which may be of slight advantage for a triathlete. A low level of body fat will help keep triathletes afloat during the swim stage, meaning they can focus their energy on propelling themselves forward.

Controlling Body Fat

Although it is clear that a degree of body fat is necessary during a triathlon, it is important that it does not increase beyond the suggested levels. Diet and controlling calorie intake is the way to maintain and control body weight. According to "OCR Physical Education," a triathlete would need to calculate his basal metabolic rate that shows the calories expended during day-to-day life, then keep a record of the amount of calories used during a race or training to eat the required amount 1. Eating too little will lower body fat too much, and eating too much will have the opposite effect.