Appendicular Lean Mass Index (ALMI)
Appendicular Lean Mass Index (ALMI) is the lean mass of the arms and legs combined, divided by height squared (kg/m²). It is commonly used to assess muscle quantity as part of a sarcopenia evaluation, and is preferred over total lean mass because limb skeletal muscle is more sensitive to aging than trunk muscle. Data are from Kelly et al. 2009, a cross-sectional DXA analysis of 15,258 US adults in NHANES 1999-2004, with percentiles derived using LMS curve fitting on the White (non-Hispanic) reference population; values differ for Black and Mexican American adults (Kelly et al. publish separate curves). Under EWGSOP2 (2019), low muscle strength indicates probable sarcopenia; low muscle quantity or quality confirms the diagnosis, and poor physical performance indicates severe sarcopenia. EWGSOP2 uses ALMI cut-offs below 7.0 kg/m² for men and 5.5 kg/m² for women as indicators of low muscle quantity, roughly the P5-P10 range of this reference population, but a percentile or ALMI value alone does not diagnose sarcopenia.
Data source: Kelly et al. (NHANES DXA) About this study
Reference population: US adults aged 20-85 from NHANES 1999-2004, measured by DXA (dual-energy X-ray absorptiometry). Separate analyses for White, Black, and Mexican American groups.
Appendicular Lean Mass Index (ALMI) Norms Chart by Age and Sex (kg/m²)
| Age | Sex | Percentile | ||||
|---|---|---|---|---|---|---|
| 5th | 25th | 50th | 75th | 95th | ||
| 20-24 | Male | 7.06 | 8.04 | 8.87 | 9.86 | 11.66 |
| Female | 5.42 | 6.17 | 6.81 | 7.58 | 9.02 | |
| 25-29 | Male | 7.13 | 8.12 | 8.94 | 9.91 | 11.63 |
| Female | 5.42 | 6.20 | 6.86 | 7.67 | 9.18 | |
| 30-34 | Male | 7.20 | 8.20 | 9.02 | 9.97 | 11.64 |
| Female | 5.43 | 6.22 | 6.90 | 7.73 | 9.30 | |
| 35-39 | Male | 7.27 | 8.27 | 9.09 | 10.03 | 11.65 |
| Female | 5.42 | 6.23 | 6.93 | 7.79 | 9.44 | |
| 40-44 | Male | 7.29 | 8.30 | 9.12 | 10.05 | 11.62 |
| Female | 5.41 | 6.24 | 6.95 | 7.83 | 9.51 | |
| 45-49 | Male | 7.29 | 8.30 | 9.11 | 10.02 | 11.54 |
| Female | 5.37 | 6.20 | 6.93 | 7.83 | 9.55 | |
| 50-54 | Male | 7.24 | 8.25 | 9.05 | 9.94 | 11.41 |
| Female | 5.36 | 6.18 | 6.90 | 7.79 | 9.50 | |
| 55-59 | Male | 7.16 | 8.17 | 8.95 | 9.81 | 11.22 |
| Female | 5.31 | 6.13 | 6.84 | 7.72 | 9.41 | |
| 60-64 | Male | 7.06 | 8.05 | 8.81 | 9.64 | 10.97 |
| Female | 5.26 | 6.06 | 6.76 | 7.62 | 9.26 | |
| 65-69 | Male | 6.93 | 7.90 | 8.64 | 9.44 | 10.71 |
| Female | 5.22 | 6.00 | 6.67 | 7.49 | 9.06 | |
| 70-74 | Male | 6.79 | 7.73 | 8.44 | 9.20 | 10.39 |
| Female | 5.17 | 5.92 | 6.57 | 7.36 | 8.86 | |
| 75-79 | Male | 6.63 | 7.54 | 8.21 | 8.92 | 10.03 |
| Female | 5.10 | 5.83 | 6.45 | 7.20 | 8.61 | |
| 80-84 | Male | 6.47 | 7.33 | 7.97 | 8.64 | 9.66 |
| Female | 5.04 | 5.74 | 6.33 | 7.04 | 8.36 | |
| 85+ | Male | 6.30 | 7.12 | 7.72 | 8.35 | 9.29 |
| Female | 4.97 | 5.64 | 6.20 | 6.87 | 8.11 | |
What to expect by age group
Among adults aged 30 to 34, the middle 50% measure 8.2 to 10.0 kg/m² for men and 6.2 to 7.7 kg/m² for women. ALMI peaks in the early 40s then declines steadily, the loss is most pronounced after age 60; men carry around 2 kg/m² more appendicular lean mass relative to height than women. Scores below 8.2 kg/m² (men) or 6.2 kg/m² (women) are typically below average for this age group; scores above 10.0 kg/m² (men) or 7.7 kg/m² (women) are above average.
| Age | Males | Females |
|---|---|---|
| 20-24 | 8.04 to 9.86 | 6.17 to 7.58 |
| 25-29 | 8.12 to 9.91 | 6.20 to 7.67 |
| 30-34 | 8.20 to 9.97 | 6.22 to 7.73 |
| 35-39 | 8.27 to 10.03 | 6.23 to 7.79 |
| 40-44 | 8.30 to 10.05 | 6.24 to 7.83 |
| 45-49 | 8.30 to 10.02 | 6.20 to 7.83 |
| 50-54 | 8.25 to 9.94 | 6.18 to 7.79 |
| 55-59 | 8.17 to 9.81 | 6.13 to 7.72 |
| 60-64 | 8.05 to 9.64 | 6.06 to 7.62 |
| 65-69 | 7.90 to 9.44 | 6.00 to 7.49 |
| 70-74 | 7.73 to 9.20 | 5.92 to 7.36 |
| 75-79 | 7.54 to 8.92 | 5.83 to 7.20 |
| 80-84 | 7.33 to 8.64 | 5.74 to 7.04 |
| 85+ | 7.12 to 8.35 | 5.64 to 6.87 |
Detailed Breakdowns
Select an age group and sex below for detailed percentile charts, tables, and ratings.
Frequently Asked Questions
What is Appendicular Lean Mass Index (ALMI)?
ALMI is the lean mass of the arms and legs (appendicular skeleton) divided by height squared (kg/m²). It isolates skeletal muscle in the limbs, which is most affected by aging and inactivity, making it the preferred clinical measure for assessing muscle health.
What are the sarcopenia thresholds for ALMI?
The European Working Group on Sarcopenia in Older People (EWGSOP2, 2019) uses ALMI below 7.0 kg/m² in men and 5.5 kg/m² in women as cut-offs for low muscle quantity. Low muscle strength is used to identify probable sarcopenia, while low muscle quantity helps confirm the diagnosis; assessment also considers physical performance and clinical context. These cut-offs correspond roughly to the P5 to P10 range of this US reference population.
How is ALMI measured?
ALMI is calculated from DXA (dual-energy X-ray absorptiometry) scans. The DXA software sums the lean mass of the arms and legs separately, and the total is divided by height in metres squared.
How does ALMI differ from total Lean Mass Index (LMI)?
LMI includes all lean mass in the body (limbs, trunk, and organs); ALMI includes only the arms and legs. Because trunk muscle declines less with age than limb muscle, ALMI is a more sensitive marker of sarcopenia.
Why do these norms use the White reference population?
Kelly et al. 2009 provides separate curves for White, Black, and Mexican American adults. This site uses the White reference as the primary comparator for a predominantly US/European audience. Black Americans tend to have higher lean mass at the same age.
Are these norms representative of non-US populations?
These norms use the White (non-Hispanic) reference curves from NHANES. Kelly et al. 2009 also provides curves for Black and Mexican American adults, Black adults tend to have higher lean mass at equivalent ages. European populations are broadly comparable to the White NHANES reference. For clinical sarcopenia screening, local or population-specific thresholds may be preferred.