Key result
Accelerometer output and oxygen uptake reserve relationships differ between adults with and without Down syndrome.
Why the study?
Physical activity intensity in adults with Down syndrome may be better reflected by percent oxygen uptake reserve than METs, but whether relationships with accelerometer output differ between adults with and without Down syndrome is unknown.
Does the relationship between accelerometer output and physical activity intensity (METs vs %VO2Reserve) differ between adults with and without Down syndrome?
Cross-Sectional (n=82)
Does the relationship between accelerometer output and physical activity intensity (METs vs %VO2Reserve) differ between adults with and without Down syndrome?
p-value: p=<0.001
Calibrating accelerometer output against %VO2Reserve rather than METs may be preferable for adults with Down syndrome due to differences in aerobic fitness.
Hip accelerometers may aid METs estimation here; leaves open prospective validation in larger, diverse cohorts before wider use.
Background The estimation of physical activity (PA) and sedentary behaviour with accelerometers is typically based on the relationship between accelerometer output and metabolic equivalents (METs)—an index of PA intensity. But for adults with Down syndrome (DS), PA intensity may be better reflected in the percent oxygen uptake reserve (%VO 2Reserve ), as it accounts for their lower aerobic fitness. This study examined if the relationship between accelerometer output and METs or %VO 2Reserve across various PAs and sedentary behaviours differs between adults with and without DS. Methods Forty‐one adults with DS (age 35 ± 9 years; 18 women) and 41 adults without DS (age 24 ± 5 years; 18 women) performed 17 tasks of varying intensity. We estimated aerobic fitness with a submaximal treadmill test. We measured oxygen uptake with portable calorimetry and expressed it as METs and %VO 2Reserve . Output from triaxial accelerometers on the nondominant hip and wrist was determined as Vector Magnitude (VM). We used multilevel modelling to evaluate the relationships of METs or %VO 2Reserve with VM, controlling for body mass index (BMI) and age. Results For the hip accelerometer, VM and the group‐by‐VM interaction significantly predicted METs ( p < 0.001; conditional R 2 = 0.82), but between‐group differences were small. For the wrist accelerometer, VM and age significantly predicted METs ( p < 0.035; conditional R 2 = 0.76). For both the hip and the wrist accelerometer, VM, the group‐by‐VM interaction and BMI significantly predicted %VO 2Reserve ( p ≤ 0.047; conditional R 2 = 0.82 and 0.74, respectively). Between‐group differences in the response to VM were larger for VO 2Reserve than METs models. Conclusion The relationship between accelerometer output and %VO 2Reserve across PAs and sedentary behaviours is different between adults with and without DS. Calibrating accelerometer output against %VO 2Reserve may be preferable to METs.
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Agiovlasitis et al. (2025) conducted a cross-sectional in Down syndrome (n=82). Down syndrome vs. Adults without Down syndrome was evaluated on Relationship of METs or %VO2Reserve with accelerometer Vector Magnitude (VM) (p=<0.001). The relationship between accelerometer output and percent oxygen uptake reserve across physical activities differs significantly between adults with and without Down syndrome (p≤0.047).
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