Bone density test (DEXA) in sports settings: what it offers and when to recommend it

DEXA (Dual-Energy X-ray Absorptiometry) is the gold standard for measuring body composition and bone density, but it's not something you'll do in your training facility: it requires radiology equipment. Still, as a trainer or physio, you should know what it is, what it offers, and when to recommend it to a client, because it's the reference data point against which all other body composition tests are validated.

What does this test measure?

A DEXA scan uses dual-energy X-rays to differentiate three body compartments with high precision:

• Fat mass (total and by region: arms, legs, trunk)
• Lean mass (muscle and other non-fat, non-bone tissue)
• Bone mineral density (BMD) — the key data point for assessing osteopenia/osteoporosis risk

Unlike skinfolds or bioimpedance, DEXA provides segmental data (how much fat/muscle is in each arm, each leg, the trunk), which is very useful for detecting asymmetries.

Equipment needed

• DEXA equipment — available at medical centers, some sports medicine clinics, and high-performance centers
• No special preparation beyond avoiding clothing with metal and, in some protocols, avoiding intense exercise in the hours beforehand

Test protocol

As a trainer, your role isn't to perform the DEXA scan, but to manage the process around it well:

1. Identify whether your client is a good candidate (see "when to recommend it" below)
2. Tell them to go to the center under conditions similar to what you'll want to replicate at follow-up (hydration, fasting if required by the center, no metal in clothing)
3. Collect the full report: total and segmental body fat %, lean mass by region, and bone density T-score/Z-score
4. Schedule the next measurement at a reasonable interval (at least 6-12 months, since bone density changes slowly)
5. Use the segmental data to detect muscle-fat asymmetries between the dominant and non-dominant sides

Common mistakes

• Repeating the DEXA scan too often (it's expensive and bone changes are slow; for fat/muscle, other more accessible tests already provide good short-term information)
• Not accounting for the center's equipment/protocol (different DEXA machines can give somewhat different absolute values)
• Ignoring the segmental data, which is exactly what sets DEXA apart from other methods

How to interpret the results

Bone mineral density (T-score, WHO):

T-score	Interpretation
≥ -1.0	Normal bone density
-1.0 to -2.5	Osteopenia
≤ -2.5	Osteoporosis

Total body fat % (DEXA reference, similar to other methods but somewhat more precise):

Body fat %	Men	Women
Athletic	6-13%	14-20%
Healthy	14-17%	21-24%
Acceptable	18-24%	25-31%

How it relates to other tests

DEXA is the "reference standard" against which the following are validated:

• Body composition test (skinfolds) — field method validated against DEXA
• Bioimpedance test — likewise often compared against DEXA to calibrate its accuracy

Integrate the reference data into your tracking

Although DEXA isn't done daily, when a client has access to one (say, once a year), that data point is gold as a calibration reference. With Movalytics you can log DEXA results as another assessment in the athlete's record, and compare them against the skinfold or bioimpedance estimates you take day-to-day, to see how much your field methods deviate from the reference standard.

Frequently asked questions

Do I need a DEXA scan to properly track body composition? No, for routine tracking, skinfolds or bioimpedance are sufficient if used consistently. DEXA adds the most value as an occasional calibration point or for specific clinical cases. Who would you recommend get a DEXA scan? High-performance athletes, people with osteoporosis risk factors (postmenopausal women, family history, long-term low-impact sports like cycling or swimming), or cases requiring high segmental precision. How often is it recommended to repeat a DEXA scan? For bone density, 1-2 years is usually reasonable unless a doctor indicates otherwise. For body composition, it could be repeated somewhat more often if the goal justifies it, but without overdoing it given the cost and radiation exposure (minimal, but present).