Relative energy cost of walking, and physical activity levels of people with intellectual disabilities.

People with ID demonstrate different gait patterns and impaired motor control.
Since walking is the most commonly reported type of physical activity in the ID
population, we suspect that a higher energy cost during walking might cause
people with ID to avoid activities and experience fatigue, and thus contribute
to their low physical activity levels. In people with motor disabilities,
neither maximal oxygen uptake, nor the oxygen uptake during walking proved to
be related to physical activity levels, but physical strain (the oxygen uptake
during walking expressed as a percentage of the VO2max) was significantly
related: people with high physical strain during walking were likely to walk
less in daily life.

The primary objective of this research proposal is to determine the differences
in maximal oxygen uptake and the oxygen uptake during walking between people
with ID and age- and gender-matched non-disabled controls, and how differences
in oxygen uptake correlate with physical activity levels of people with ID,
compared to non-disabled controls. We will also determine the agreement between
the oxygen uptake and the physical activity monitor output during walking in
adults with ID and the validity of two physical activity questionnaires when
compared to the physical activity monitor output of physical activity in adults
with ID.

This study has a cross-sectional research design. Participants will visit the
Clinical Movement Lab of the Erasmus MC University Medical Center twice, with
at least 1 week in between, while wearing an activity monitor in the time
between the two visits.

The participants will visit the laboratory twice and wear physical activity
monitors in between the two vistis. During maximal aerobic exercise on the
treadmill, oxygen uptake is monitored to determine cardiovascular capacity.
Oxygen uptake is also measured during comfortable walking overground and on the
treadmill, at different speeds. Differences with the participants without ID
will be analyzed. The hypothesized physiological barriers to be physically
active, and the physiological mechanisms underlying the differences in oxygen
uptake, are fundamentally related to having an intellectual disability, and
this research project will therefore be carried out in, and benefit this
specific group. There will be no direct benefit to the subjects for
participating in this research. Due to thorough screening beforehand, only
participants with low risk will participate in maximal exercise testing.