Baumgartner used the relative skeletal muscle index (RSMI) and percent body fat to separate adults into different populations. The author is from the University of New Mexico in Albuquerque.
relative skeletal muscle index in kg per square meter (RSMI) =
= (mass of skeletal muscle in kg) / ((body height in meters) ^2)
where:
• The skeletal muscle mass may be directly measured (DXA, CT, MRI) or estimated by equation.
Sarcopenia: RMSI < - 2SD below the sex specific mean for the index in healthy young adults (mean age 29 years); males 7.26 kg per square meter, females 5.45 kg per square meter.
Obesity: Percent body fat > median for each sex (males 27%, females 38%)
NOTE: Defining obesity based on median value could be misleading as the prevalence of obesity increases in the population (such as is occurring in the United States).
Males
Relative Skeletal Muscle Index in kg per square meter
Percent Body Fat
Category
> 7.26
< 27%
normal
> 7.26
>= 27%
obese
<= 7.26
< 27%
sarcopenic
<= 7.26
>= 27%
sarcopenic obese
after page 440
Females
Relative Skeletal Muscle Index in kg per square meter
Percent Body Fat
Category
> 5.45
< 38%
normal
> 5.45
>= 38%
obese
<= 5.45
< 38%
sarcopenic
<= 5.45
>= 38%
sarcopenic obese
after page 440
NOTE: The graphical representation in Figure 1 (page 440) uses the SKMI for women and the percent body fat for men to represent the categories, which seems discordant with the text.
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