Guide
Muscle Mass, Sarcopenia, and Longevity
In short
Muscle mass tends to decline with age, and low muscle (sarcopenia) is linked to weakness, falls, and loss of independence. A DEXA scan measures appendicular lean mass and calculates ALMI, the index clinicians use to flag low muscle. Common thresholds are below 7.0 kg/m² for men and 5.5 kg/m² for women, but interpretation is a clinical judgment.
Muscle isn’t just for strength. Maintaining muscle as you age is one of the better-supported ways to protect mobility, independence, and metabolic health. A DEXA scan measures it precisely.
Appendicular lean mass and ALMI. DEXA measures the lean tissue in your arms and legs (appendicular lean mass) and divides it by height squared to give the appendicular lean mass index (ALMI), the standard way to judge whether muscle mass is low for your size. It’s the same idea as BMI, but for muscle rather than total weight, and measured directly rather than estimated.
What sarcopenia is, and the thresholds. Sarcopenia is the age-related loss of muscle mass and function, and it’s associated with weakness, falls, fractures, and loss of independence. The most widely used clinical thresholds for low muscle mass, from the European Working Group on Sarcopenia in Older People (EWGSOP2), are an ALMI below 7.0 kg/m² for men and below 5.5 kg/m² for women. Being below a threshold isn’t a diagnosis on its own. Full assessment of sarcopenia also considers muscle strength and physical performance, which a scan doesn’t measure.
Why measure it before there’s a problem. Muscle is easier to keep than to rebuild. A baseline ALMI in your 40s, 50s, or 60s, tracked over time, shows whether you’re holding muscle or losing it, early enough to act. That’s the longevity angle: not a number to hit, but a trend to protect.
A measurement your physician interprets. DEXA gives the number; what it means for you depends on your age, strength, activity, and health. At Wayne DEXA a physician reviews your results with you, and any diagnosis or plan rests with the clinician who manages your care.
Common questions
What is ALMI?
Appendicular lean mass index: the lean tissue in your arms and legs divided by height squared. It's the standard measure clinicians use to assess whether muscle mass is low. ALMI is defined on directly measured lean mass. An InBody's water-based estimate isn't the same measurement.
What ALMI counts as low muscle mass?
The widely used EWGSOP2 thresholds are below 7.0 kg/m² for men and below 5.5 kg/m² for women, but this is one part of a sarcopenia assessment, not a standalone diagnosis. Notably, the clinical thresholds themselves are defined using DXA, not bioimpedance, which is one reason DXA is the reference for this.
Is low muscle mass the same as sarcopenia?
Not quite. Sarcopenia also involves reduced muscle strength and physical performance, which a scan doesn't measure. Low ALMI is one component. DXA measures the muscle-mass component directly, whereas an InBody infers it from body water.
When should I get a baseline?
Muscle is easier to keep than rebuild, so a baseline in midlife that you track over time is useful. A DXA baseline is worth more than an InBody one because it won't shift with how hydrated you were that day. Timing is best discussed with your physician.
How much does a scan cost?
$250, flat, no referral or insurance needed.
Related guides
- DEXA for AthletesRegional lean mass, left-right symmetry, and tracking real change across a season.
- How to Read Your DEXA ResultsA plain-language walkthrough of body fat, lean mass, visceral fat, and T-scores.
- Bone Density and T-Scores After MenopauseWhat your T-score means, and who guidelines recommend for bone density screening.
The scan and pricing
The scan
A complete picture of your body composition
- About ten minutes, lying comfortably on a padded table while the scanner passes over you.
- No fasting, no needles, no discomfort.
- A clear, easy-to-read report explaining your results.
Pricing
$250
Single scan
One flat price. No memberships, no hidden fees. Reserve your time online; payment is collected in full at booking.
A complete DEXA body composition scan is $250, flat. No referral or insurance needed. Reserve a time online; payment is collected in full at booking.
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