Relative aerobic load and energy cost of balance control in elderly people walking with a unilateral lower limb prosthesis

Learning to walk with a prosthesis is a challenge. Part of the motor and
sensory system has been removed and walking becomes a task which requires
continuous attention. Although a recent review shows that there is limited
knowledge available concerning the relationship between walking ability and
physical capacity, it is generally known that physical capacity plays a crucial
role in regaining walking ability. Due to long periods of inactivity preceding
and following amputation and co-morbidity accompanying the amputation, physical
capacity is reduced. Concurrently, the physical load of walking with an
prosthesis amputation is increased. If the physical load exceeds a reasonable
fraction of the available physical capacity, walking ability will be
restricted. In order to train people to attain an adequate level of walking
ability, evidence-based knowledge of both physical load and physical capacity
and their interaction is required. Regaining walking ability can be
accomplished by either increasing physical capacity or reducing the physical
load of walking. In order to reduce the physical load during walking, an
explanation for the increased physical load needs to be established. An
explanation often proposed in literature is a reduced stability of amputee
gait, requiring more balance control to maintain a stable walking pattern as to
prevent falls. Since stability of gait has been difficult to assess, its
relation to energy cost has not yet been investigated.

The objective of this study is twofold. The first objective is to investigate
the relative aerobic load during walking of people with a lower limb
prosthesis. The second objective is to investigate the influence of balance
control as a possible physical factor responsible for the increased aerobic
load of walking with a lower limb prosthesis.

quasi experimental study

The patients will visit the rehabilitation centre twice. During the first visit
the participant is first screened by a physiatrist to check for abnormalities.
The participant is asked to walk twice at their comfortable speed on a
treadmill. At one of these trials balance is perturbed by directing attention
away from the walking task. In addition to the comfortable walking speed the
patient is asked to walk on a treadmill for four minutes at four fixed speeds,
proportional to his/her comfortable walking speed. Participants will wear a
safety harness, attached to the ceiling. During the second visit, the
participant is asked to perform a 10 meter walk test, a timed up-and-go test, a
one-legged balance test and a two minute walk test. After a sufficient rest
period, a maximal graded exercise test is conducted using a one-legged cycle
ergometer. Oxygen, blood pressure, heart rate and ECG are recorded throughout
the experiment so cardiovascular responses are continuously monitored.