Objective physical arm activity assessment

Physical inactivity in healthy subjects increases the risk of developing a
number of chronic diseases, such as chronic obstructive pulmonary disease
(COPD). Indeed, physical inactivity is one of the lifestyle-related health
determinants. Therefore, guidelines recommend that a minimum of 30 minutes of
daily physical activity of moderate intensity is necessary to maintain physical
fitness, and those not meeting this standard are considered insufficiently
active.

Decreased activity in daily life is likely to play a key role in the
development and progression of skeletal muscle weakness and a poor exercise
performance in patients with COPD. Indeed, a *downward disease spiral* has been
hypothesized, in which advancing dyspnoea leads to a sedentary lifestyle and
de-conditioning of the muscles, and thus further daily physical inactivity.
Exercise-based pulmonary rehabilitation programs have been shown to effectively
improve quality of life, muscle function and exercise capacity in patients with
COPD which cannot be attributed to changes in forced expiratory volume in the
first second (FEV1). Moreover, studies of skeletal muscle impairment in COPD
have demonstrated that upper limb muscles were less affected than lower limb
muscles (strength, endurance and exercise capacity). It is unknown whether and
to what extent differences in muscle dysfunction between arm and leg muscles
reflect a difference in their daily use or an innate difference in the
susceptibility to disease.

To evaluate whether and to what extent differences in muscle dysfunction
between arm and leg muscles in COPD patients reflect a difference in their
daily use, daily physical activity in relation to muscle function needs to be
assessed. For this purpose analyses of daily physical activity have to focus on
relevant subsystems, e.g. performance in arm or leg tasks; whole body
measurements will be too global to pinpoint loci of interest. Compared with
whole body or leg activity assessment, arm function presents a complex problem.
Although several studies evaluated activity monitors worn on the arm in COPD
patients to measure whole body activity or specific arm exercises, none of
these studies assessed the use of these monitors to evaluate performance of
common daily arm activities. It is unknown what the optimal placement of the
monitor is to evaluate daily arm activities and how the monitor output is
related to muscle effort. Therefore, the aim of this study is to validate a new
arm activity monitor (CAM_arm) in COPD patients with healthy subjects as
reference.

Primary objective:

Study A: Development, validation and reproducibility of a method to assess arm
activity.
Study B: Investigate the association between muscle effort and arm use during a
series of daily activities in COPD patients and healthy age matched controls.

Secondary objectives (study A):
1. Evaluate the optimal sensor placement.¬ For this purpose the sensorsleeve
will be worn during a pilot study on young healthy volunteers. The sensorsleeve
contains three 3-axial accelerometers. These will be worn on the lower arm at
the dorsal side, between the ulnar and radial styloid process (ACCwrist), on
the upper arm at the dorsal side, just above the olecranon (ACCelbow) and on
top of the acromion (ACCshoulder). The optimal sensor placement will be
determined as the sensor that reached the highest amount of seconds correctly
categorized samples. The sensor of study B will be placed at the optimal sensor
placement.
2. Define thresholds for activity classification. For each sensor two
thresholds will be defined to categorize three levels of arm orientations (th1
and th2) and two thresholds will be defined to categorize three levels of arm
activity intensity (th3 and th4). These four thresholds will be used to
classify activities into 9 categories: 1) low orientation and low intensity, 2)
low orientation and medium intensity, 3) low orientation and high intensity, 4)
medium orientation and low intensity, 5) medium orientation and medium
intensity, 6) medium orientation and high intensity, 7) high orientation and
low intensity, 8) high orientation and medium intensity, 9) high orientation
and high intensity.
3. Test the reproducibility of the accelerometers to categorize activities.

Secondary objectives (study B: main study):
1. For the main study only one 3-axial accelerometer will be worn (CAM_arm). To
categorize arm activities the method developed in study A will be used. The
objective is to evaluate arm orientation and intensity while performing a
series of daily arm activities in COPD patients and healthy subjects.
2. Assess the relation between arm orientation and intensity with muscle effort
of the major arm / shoulder muscles (biceps brachii, triceps brachii, m.
deltoideus and m. trapezius pars descendens) in COPD patients and healthy age
matched controls. COPD patients will consist of a group with and without lung
hyperinflation to investigate whether the association between muscle effort and
arm use is similar in both groups.

For the pilot study (study A) students of Maastricht University will be asked
to perform a standardized protocol on two separate days in which activities and
postures are strictly controlled. The total duration of study A is 30 minutes
(two times 15 minutes on separate days).

For the main study (study B), COPD patients and healthy age matched subjects
will perform a series of 15 daily activities in a randomized order at their
preferred speed and arm orientation. The total duration of study B is 30
minutes. Other variables that will be taken into account are date of birth,
gender, weight, body length which will be taken from the patient*s medical
recordings. In healthy subjects these variables will be measured. All subjects
will be asked how they experienced wearing the CAM.

Not applicable