The role of the relative aerobic load of walking and walking behaviour after spinal cord injury

The group of people with spinal cord injury with a walking ability has
increased in recent decades. Knowledge about the physical activity in this
group is limited, but recent research by our project team suggests that part of
this group shows a strongly unfavorable (course in) physical activity in the
year after inpatient rehabilitation, including relatively little standing and
walking. Less physical activity is associated with higher mortality, poorer
health and lower well-being.
The energy consumption during walking, and especially the energy consumption
relative to the maximum oxygen uptake (relative aerobic load of walking),
probably plays an important role in the extent to which people with a spinal
cord injury walk in daily life. This means that relative aerobic load of
walking may be an important target for rehabilitation treatment. However,
nothing is known about the relationship between the relative aerobic load of
walking and the amount of walking of people with a spinal cord injury.
Knowledge about this relationship is necessary for the development and
personalization of interventions to promote physical activity in this growing
population.

The primary aim is to determine whether the relative aerobic load of walking is
a determinant of the amount of walking in daily life in people with a chronic
spinal cord injury with a walking function. Secondary goals are to gain insight
into other determinants of the amount of walking, the energy use in daily life
as a result of walking, the overall physical activity (besides walking also
other physical activities, standing and sedentary behaviour) and their
determinants, total energy consumption in daily life, fitness, and health (bone
density, body composition, cardiometabolic profile) in the chronic phase.
In addition, the energetic load of walking and exercise behavior in persons
with a chronic spinal cord injury is compared with that of persons without
disabilities.
Finally, because performing a maximal cycling test with breath gas analysis to
determine aerobic capacity (fitness) is time-consuming and costly and not
feasible in all patients due to contraindications to maximal exercise, the
utility of an accerelometry-based tool to estimate aerobic capacity (Seismofit)
is evaluated in patients with spinal cord injury without the need for exercise.

Cross-sectional study

Participants are invited for 1 (part of a) day for questionnaires, physical
examination, clinical testing, an exercise test (bicycle test), a measurement
with the Seismofit, and gait test, and for optional blood analysis and a
Dexa-scan. Sufficient rest is planned between the activities. Such protocols
have been shown to be feasible in previous studies in comparable patient
populations (MEC 2010-178; SAB: MEC-2017-523; SCI/MS: MEC-2018-025). For these
measurements, 1 (part of the) day has been deliberately chosen to limit the
travel load.
Exercise behavior is measured in the home situation for 7 days with two
activity monitors that are attached to the thigh (with special skin-friendly
foil) and the wrist. Further, a heartrate belt is worn for 2 days. The
wearables are small and ensures little load; people can perform their normal
daily activities. During this period, participants are asked to keep a diary.
A maximum exercise test with breath analysis is the gold standard for measuring
aerobic capacity and is frequently used in regular care and scientific
research. The *Safety Guidelines for Maximum Exercise Test* of the Rijndam
Movement Lab are followed around the test. Participants are minimally screened
for (relative) contraindications and a resting ECG is made immediately prior to
the test. During the test, the safety protocol of the Movement Lab applies.
The measurement with the Seismofit to estimate the aerobic capacity is without
risk.
Blood sampling (cardiometabolic profile) indicates a low risk of complications;
in particular, there is a risk of a hematoma. Blood sampling can be experienced
as mentally taxing. Therefore, blood analysis will be optional (target: n=40).
With a single Dexascan (total body and bone density lumbar spine and femur) the
radiation load is 0.004 mSv. This means that the risk is very low (category 1).
This measurement is optional (target: n=40).
By participating in the study, participants gain insight into their own
fitness, energetic load of walking, total exercise behavior and health. This is
fed back to individual participants. Further, they have no direct benefit from
participating in the study. We expect the study to lead to optimization of
treatment in runners with spinal cord injury; the participants of the study may
benefit from this in the future.