Physical Education · Ch 6 — Test, Measurement & Evaluation
BMI, Waist-Hip Ratio and Skinfold Measures (3-Site)
6.5
BMI, Waist-Hip Ratio and Skinfold Measures (3-Site)
Two people can weigh exactly the same on a bathroom scale yet differ completely in health and athletic readiness - one lean and muscular, the other carrying a lot of fat. This is why coaches and clinicians look beyond body weight to body composition.
What body composition means and why it matters
Body composition is the proportion of fat mass to lean (fat-free) mass - how much of the body is fat and how much is muscle, bone, water and organs. It matters more than weight alone because:
- Health depends on it - excess fat, especially around the abdomen, is linked to heart disease, type-2 diabetes and other conditions, while a healthy proportion of lean mass supports metabolism and function.
- Sport performance depends on it - in most sports a high proportion of lean mass and a controlled level of fat improve strength, speed and endurance, since fat is "dead weight" that must be carried without contributing to force.
The three prescribed measures
The syllabus prescribes three practical ways to assess body composition; each estimates something different and has its own full procedure below:
| Measure | What it estimates | Role |
|---|---|---|
| Body Mass Index (BMI) | Weight relative to height | A quick screening standard for underweight / normal / overweight / obese |
| Waist-Hip Ratio (WHR) | The distribution of fat (how central it is) | Flags abdominal obesity and related cardiovascular/metabolic risk |
| 3-site Skinfold | Subcutaneous fat thickness -> body-fat % | A more direct field estimate of how much of the body is fat |
- BMI uses only height and weight - fast and cheap, but cannot separate fat from muscle (see 6.5.1). …