NHANES 1999-2006 calf circumference
About this reference
FitnessNorms derived weighted P5, P25, P50, P75, and P95 calf-circumference estimates from four public NHANES releases (1999-2000 through 2005-2006). Body-measures, demographics, and DXA files were merged by participant ID; the five multiply imputed DXA records were reduced to one participant record using _MULT_ = 1. The complete-case rules reproduce the 17,856-person eligible cohort reported by Gonzalez et al. exactly. The paper says that 67 records were removed using an IQR method with a threshold of 3, but it does not specify the grouping or implementation. A conventional global Tukey fence (below Q1 - 3 × IQR or above Q3 + 3 × IQR) removes 17 records, and tested sex, age, race/ethnicity, and BMI groupings did not reproduce both the paper's removal count and sex split. FitnessNorms therefore publishes a clearly separate 17,839-person derivation using the conventional rule. This avoids attributing the paper's n=17,789 to results that cannot be exactly replicated. Eight-year MEC weights follow the CDC combination rule: the 1999-2002 four-year weights are multiplied by 0.5, and each 2003-2006 two-year weight is multiplied by 0.25. Weighted empirical quantiles use midpoint cumulative-weight interpolation. The weighted sex means round to the paper's reported 39.3 cm for men and 38.2 cm for women. P25 and P75 are newly derived; survey-design standard errors are not estimated.
Known limitations
- US population only and data collected in 1999-2006. NHANES discontinued maximal calf circumference after 2005-2006, so these values are not a current-cycle snapshot.
- This is an internal FitnessNorms derivation from CDC public microdata, not the published Gonzalez et al. percentile table. The paper's eligible cohort is reproduced, but its unspecified threshold-3 IQR implementation and 67 outlier removals are not.
- Calf circumference includes muscle, subcutaneous fat, and intramuscular fat. A population percentile is not a direct measure of muscle mass and is not a sarcopenia diagnosis.
- Weighted point estimates are reported without survey-design standard errors or confidence intervals.
- Cross-sectional age differences do not show how an individual person's calf circumference changes over time.
- Public RIDAGEYR is top-coded at age 85 in these NHANES releases. The 70+ bracket therefore pools observed ages 70-84 with everyone aged 85 and older, limiting age resolution in the oldest group.
- P25 and P75 were derived by FitnessNorms because Gonzalez et al. published subgroup P5, P50, and P95 values rather than an all-race age-by-sex five-percentile table.