Anthropometry does not fully explain low fitness among adults with Down syndrome.
Waist size, not BMI, predicts cardio fitness in adults with Down syndrome.
01Research in Context
What this study did
Researchers tested how well body-size numbers predict fitness in adults with Down syndrome. They used lab-grade DEXA scans and treadmill VO2 peak tests. They compared these adults to typical adults of the same size.
What they found
Adults with Down syndrome had lower VO2 peak even after matching body size. Regular tools like BMI, body-fat percent, and limb lengths gave useless fitness guesses. Only waist size and waist-to-height ratio linked to true fitness.
How this fits with other research
Cummings et al. (2024) found BMI tells us nothing about motor skill in youth with ID. That looks like a clash, but their group mixed diagnoses and did not check waist measures. Waist still wins in Down-only adults.
González-Agüero et al. (2011) already warned that BMI misses hidden fat in youths with Down syndrome. Beck et al. (2021) now extends the warning to adults and adds VO2 peak to the list of missed outcomes.
Iglesias-Díaz et al. (2025) pooled ten trials showing strength training boosts strength in Down syndrome. Their review used DEXA baselines like this study, so the same waist rule should guide future exercise trials.
Why it matters
Stop plugging adult Down-syndrome clients into standard fitness charts. You will under-estimate risk and set wrong goals. Measure waist once, use waist-to-height ratio, and plan cardio from that number. Keep the rest of your intake time for real performance tests like six-minute walk or VO2 if you have the gear.
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02At a glance
03Original abstract
BACKGROUND: Cardiorespiratory fitness, expressed as peak oxygen uptake during exercise (VO2 peak), is an important predictor of cardiovascular health and is related to anthropometry in the general population. Individuals with Down syndrome (DS) have reduced cardiorespiratory fitness and often exhibit different anthropometrics compared with the general population. Interestingly, the relation between anthropometry and cardiorespiratory fitness found in the general population is not apparent in individuals with DS. However, accurate measures with dual energy X-ray absorptiometry (DEXA) scan have not been used to investigate this relationship in this population. The purpose of this paper was to investigate the relationship between accurate measures of anthropometry and cardiorespiratory fitness in adults with DS compared with an age-matched and sex-matched control group. METHODS: Anthropometrics (height, weight, waist and hip circumference, body composition via DEXA) and cardiorespiratory fitness (VO2 peak, measured during a graded maximal exercise test) were assessed in adults with (n = 9; 25 ± 3 years; 6 male patients) and without DS (n = 10, 24 ± 4 years; 5 male patients). RESULTS: Participants with DS were shorter (P < 0.01) than without DS and had a higher body mass index (P < 0.01), waist circumference (WC) (P = 0.026) and waist/height ratio (WHtR) (P < 0.01), but similar weight, body surface area (BSA), waist/hip ratio and body composition (P > 0.05). Participants with DS had significantly lower relative VO2 peak and VO2 peak corrected for total lean mass (TLM), but similar absolute VO2 peak, compared with without DS. In participants with DS, only WC and WHtR were associated with VO2 peak, whereas in participants without DS, height, weight, BSA, TLM, leg lean mass and body fat percentage were associated with VO2 peak. CONCLUSIONS: These results suggest that the relation between anthropometry and cardiorespiratory fitness found in the general population is not the same in adults with DS and that anthropometrics do not fully explain cardiorespiratory fitness in adults with DS. Further research into potential alternative explanations is required.
Journal of intellectual disability research : JIDR, 2021 · doi:10.1111/jir.12815