Measuring Muscle Mass in Adults With Intellectual Disabilities: The Reliability and Construct Validity of Calf Circumference.
Calf tape is trusty within one rater for adults with ID, yet it only partly lines up with lab muscle scans.
01Research in Context
What this study did
The team wanted a cheap way to track muscle in adults with intellectual disability.
They taped calf size and compared it to a pricey body-fat scan.
Same worker measured each leg twice to see if the tape gave steady numbers.
What they found
One person got the same calf number again and again.
But the tape only matched the scan so-so.
It is reliable, yet only partly true.
How this fits with other research
Bartlo et al. (2011) showed exercise boosts strength in this group, so we need quick muscle checks.
Bhaumik et al. (2009) warned that mobility studies use wild different tools; calf tape could give us one shared ruler.
Rieth et al. (2022) proved a short 15-minute test can be both reliable and valid, hinting that calf tape might get better with new cut-off rules.
Why it matters
You now have a no-cost, travel-friendly way to watch muscle change in day programs or homes.
Use the tape yourself for trend lines, but pair it with a short walk test or grip gauge before big choices like adding PT hours.
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Pick two clients, measure calf twice, chart both numbers, and re-test next week to start a trend line.
02At a glance
03Original abstract
BACKGROUND: The amount of muscle mass is an important criterion to diagnose sarcopenia. Two feasible methods for measuring muscle mass in adults with intellectual disabilities (ID) are bioelectrical impedance analysis (BIA) and calf circumference (CC). CC measurements are more accessible, cheaper and easier to use than BIA in adults with ID. This study aimed to investigate the construct validity and intrarater reliability of CC to estimate muscle mass compared to BIA in adults with mild and moderate ID and cardiovascular risk factors (CVRF). METHODS: This study was part of the PRET study (NTR, NL8382), which examined the effect of Progressive Resistance Exercise Training on cardiovascular risk factors in 36 adults with ID (55.58 years, SD: 12.89). Construct validity was analysed with Pearson's correlations between CC and BIA measurements (skeletal muscle mass [SMM], segmental muscle mass [SegMM] and skeletal muscle index [SMI]). The intrarater reliability was analysed with the intraclass correlation coefficient (ICC). RESULTS: The correlation between CC and SMM was 0.19 (95% CI [-0.16, 0.49]), 0.60 (95% CI [0.33, 0.78]) between CC and SegMM and 0.69 (95% CI [0.47, 0.83]) between CC and SMI. The ICC was 0.94 (95% CI [0.89, 0.97]). CONCLUSIONS: The excellent intrarater reliability of CC indicates that CC measurements are reliable within the same assessor for adults with ID and CVRF. However, the use of CC to estimate muscle mass compared to BIA remains questionable.
Journal of intellectual disability research : JIDR, 2026 · doi:10.1016/j.metabol.2023.155533