OBJECTIVES: To establish the prevalence of sarcopenia in older Americans and to test the hypothesis that sarcope- nia is related to functional impairment and physical dis- ability in older persons. DESIGN: Cross-sectional survey. SETTING: Nationally representative cross-sectional sur- vey using data from the Third National Health and Nutri- tion Examination Survey (NHANES III). PARTICIPANTS: Fourteen thousand eight hundred eigh- teen adult NHANES III participants aged 18 and older. MEASUREMENTS: The presence of sarcopenia and the relationship between sarcopenia and functional impairment and disability were examined in 4,504 adults aged 60 and older. Skeletal muscle mass was estimated from bioimped- ance analysis measurements and expressed as skeletal mus- cle mass index (SMIskeletal muscle mass/body mass � 100). Subjects were considered to have a normal SMI if their SMI was greater than -one standard deviation above the sex-specific mean for young adults (aged 18-39). Class I sarcopenia was considered present in subjects whose SMI was within -one to -two standard deviations of young adult values, and class II sarcopenia was present in subjects whose SMI was below -two standard deviations of young adult values. RESULTS: The prevalence of class I and class II sarcope- nia increased from the third to sixth decades but remained relatively constant thereafter. The prevalence of class I (59% vs 45%) and class II (10% vs 7%) sarcopenia was greater in the older ( � 60 years) women than in the older men ( P � .001). The likelihood of functional impairment and disability was approximately two times greater in the older men and three times greater in the older women with class II sarcopenia than in the older men and women with a normal SMI, respectively. Some of the associations be- tween class II sarcopenia and functional impairment re- mained significant after adjustment for age, race, body mass index, health behaviors, and comorbidity. CONCLUSIONS: Reduced relative skeletal muscle mass in older Americans is a common occurrence that is signifi- cantly and independently associated with functional im- pairment and disability, particularly in older women. These observations provide strong support for the prevailing view that sarcopenia may be an important and potentially re- versible cause of morbidity and mortality in older persons. J Am Geriatr Soc 50:889-896, 2002.

Low relative skeletal muscle mass (sarcopenia) in older persons is associated with functional impairment and physical disability.

http://drop-kicker.com/wp-content/uploads/2014/01/kyle-bia.pdf

Bioelectrical impedance analysis--part I: review of principles and methods.

OBJECTIVE: To evaluate whether the homeostasis model assessment (HOMA) is a reliable surrogate measure of in vivo insulin sensitivity in humans. RESEARCH DESIGN AND METHODS: In the present study, we compared insulin sensitivity as assessed by a 4-h euglycemic (approximately 5 mmol/l) hyperinsulinemic (approximately 300 pmol/l) clamp with HOMA in 115 subjects with various degrees of glucose tolerance and insulin sensitivity. RESULTS: We found a strong correlation between clamp-measured total glucose disposal and HOMA-estimated insulin sensitivity (r = -0.820, P

https://care.diabetesjournals.org/content/diacare/23/1/57.full.pdf

Homeostasis model assessment closely mirrors the glucose clamp technique in the assessment of insulin sensitivity: studies in subjects with various degrees of glucose tolerance and insulin sensitivity.

Assessment of fat-free mass using bioelectrical impedance measurements of the human body

This study was conducted to validate the relationship between bioelectrical conductance (ht2/R) and densitometrically determined fat-free mass, and to compare the prediction errors of body fatness ...

Validation of tetrapolar bioelectrical impedance method to assess human body composition.

A simple, inexpensive method of determining total body water using a tracer dose of D2O and infrared absorption of biological fluids.

Detection of labile zinc-binding ligands in biological fluids by modified gel filtration chromatography.

Boron isotope ratios in commercial produce and boron-10 foliar and hydroponic enriched plants

The commercial availability of inductively coupled plasma-mass spectrometry technology (ICP-MS) has presented the opportunity to measure the boron concentrations and isotope ratios in a large number of samples with minimal sample preparation. A typical analytical sequence for fecal samples consists of 25 acid blanks, 1 digestion blank, 5 calibration solutions, 4 standard reference material solutions, 10 samples, and 4 natural abundance bias standards. Boron detection limits (3 x 1 sigma) for acid blanks are 0.11 ppb for 10B, and 0.40 ppb for 11B. Isotope ratios were measured in fecal samples with 20 to 50 ppb boron with < 2% relative standard deviation. Rapid washout and minimal memory effects were observed for a 50 ppb beryllium internal standard, but a 200 ppb boron biological sample had a 1.0 ppb boron memory after a 6-min washout. Boron isotope ratios in geological materials are highly variable; apparently this variability is reflected in plants of a fixed natural abundance value for boron requires that a natural abundance ratio be determined for each sample or related data set. The natural abundance variability also prevents quantitation and calculation of isotope dilution by instrument-supplied software. To measure boron transport in animal systems, 20 micrograms of 10B were fed to a fasted rat. During the 3 days after a 10B oral dose, 95% of the 10B was recovered from the urine and 4% from the feces. Urinary isotope ratios, 11B/10B, changed from a natural abundance of 4.1140 to an enriched value of 0.95077, a 77% change.(ABSTRACT TRUNCATED AT 250 WORDS)

Phyllis E. Johnson

Papers

Assessment of fat-free mass using bioelectrical impedance measurements of the human body

A simple, inexpensive method of determining total body water using a tracer dose of D2O and infrared absorption of biological fluids.

Detection of labile zinc-binding ligands in biological fluids by modified gel filtration chromatography.

Boron isotope ratios in commercial produce and boron-10 foliar and hydroponic enriched plants

Use of inductively coupled plasma-mass spectrometry in boron-10 stable isotope experiments with plants, rats, and humans.