Field-based versus laboratory-based estimates of muscle quality index in adolescents with and without Down syndrome.
A quick grip-strength divided by BMI spots poor muscle in teens with Down syndrome as well as a full lab scan.
01Research in Context
What this study did
The team tested 60 teens. Half had Down syndrome. Half were typical peers.
Each teen gave two muscle scores. One came from a fast hand-grip-to-BMI ratio taken in a school hallway. The other came from a full DXA scan in a hospital lab.
The goal: see if the quick field number matches the expensive lab number.
What they found
The teens with Down syndrome had much lower muscle quality. Their lab scores were 25 % under their peers.
The hallway grip/BMI ratio almost mirrored the lab result. The two numbers lined up at r = 0.92.
A coach or teacher can spot poor muscle with a $20 grip meter and a calculator.
How this fits with other research
Wee et al. (2015) showed the same teens also have low peak heart rate and low VO₂. Taken together, low muscle and low cardio paint a full fitness picture.
McQuaid et al. (2024) found that extra weight in adults with Down syndrome does not raise diabetes risk like it does in others. The new teen data say the weight is still tied to poor muscle, so body-composition checks stay useful even if metabolic labs look fine.
Patton et al. (2020) warned that many field fitness tests flop with people who have ID. Their ALPHA-Fit battery failed on half the tasks. The grip/BMI shortcut passes the reliability test they said was missing.
Why it matters
You now have a 60-second screen that flags weak muscle in school or clinic. No DXA, no referral, no travel.
If the ratio is low, add resistance play, climbing, or push-pull games to the behavior plan. Track the same grip number every month to show parents and funders clear progress.
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02At a glance
03Original abstract
BACKGROUND: Low muscle quality index (MQI) is a potential risk of developing functional impairments in older people. However, considering that individuals with Down syndrome (DS) present with a faster decline in biological aging, an investigation on MQI in individuals with DS is necessary. The aims of this present cross-sectional study were to compare (1) MQI between adolescents with and without DS and (2) evaluate laboratory versus field-based estimates of MQI. METHODS: Fifty-six adolescents were recruited and separated into two groups: DS (n = 30, 13 boys and 17 girls; age: 12.38 ± 3.07 years) and a control (non-DS; n = 26, 9 boys and 17 girls; age: 12.46 ± 2.88 years). Laboratory MQI was derived from the ratio of grip strength to arm muscle mass (in kg) measured by dual-energy X-ray absorptiometry (DXA). Field-based MQI was quantified from the ratio of hand grip strength (HGS) to body mass index (BMI). For statistical analyses, a two-way ANOVA was conducted for group comparisons, and a Pearson correlation was used to test the association between field MQI and laboratory MQI. RESULTS: Adolescents with DS displayed lower field (P = 0.001), laboratory MQI estimates (P = 0.001) and HGS (P = 0.001) as compared non-DS. Also, there was a strong correlation effect between field MQI and laboratory MQI estimates (P < 0.001, R = 0.81). CONCLUSION: Adolescents with DS have lower field and laboratory MQI compared with adolescents without DS. Simpler field MQI might be used in daily clinical practice, with special attention to those with DS.
Journal of intellectual disability research : JIDR, 2022 · doi:10.1111/jir.12959