Cardiopulmonary Profile of Individuals with Intellectual Disability

Individuals with intellectual disabilities (ID) are often sedentary and have low fitness levels. Current knowledge supports the existence of physiological barriers resulting in low fitness and exercise intolerance in individuals with Down syndrome, which might be applicable to other ID etiologies. If physiological barriers exist in ID, this would require adaptation of the physical activity guidelines.

The aim of this study was to assess differences in cardiopulmonary profiles, including maximal oxygen uptake, during a cardiopulmonary exercise test in individuals with ID without Down syndrome and healthy controls.

Participants performed an incremental cardiopulmonary exercise test on a treadmill until exhaustion. Outcomes were peak heart rate (HRpeak), absolute peak oxygen uptake (V˙O2peak), relative V˙O2peak, peak minute ventilation, peak CO2 expenditure, oxygen uptake efficiency slope, V˙E/V˙CO2 slope, absolute O2 pulse, relative O2 pulse, difference from predicted HRpeak, HR reserve, RERpeak, ventilatory threshold (VT), and VT as a percentage of V˙O2peak. Differences between groups were analyzed with Student's t-tests and multiple linear regression after adjusting for potential confounders (sex, age, body mass index, and activity level).

Individuals with ID had worse outcomes on all of the cardiopulmonary outcomes, except for VT expressed as a percentage of V˙O2peak and V˙E/V˙CO2 slope (P < 0.05). Having ID was an independent predictor of reduced physiologic function during exercise (P < 0.05).

These results demonstrate that individuals with ID present exercise intolerance potentially related to lower HRpeak and impairments in ventilatory function, and these results also suggest the possibility of peripheral muscle hypoperfusion. Existing physical activity guidelines likely underestimate the actual intensity of activity performed by individuals with ID and need to be adapted.