194
· DOS Abstracts
Objectively measured physical activity –
reference data obtained from a Dutch population
with a three-axial accelerometer
Signe Kierkegaard, Inger Mechlenburg, Bernd Grimm, Ide Heyligers,
Rachel Senden
Orthopaedic Research, Aarhus University Hospital, Denmark; Department
Orthopaedic Surgery & Traumatology, Atrium Medical Center, Heerlen, The
Netherlands
Background:
Self-reported physical activity (PA) is often under/overestimated
and influenced by patient satisfaction and pain. Thus, PA after surgery or reha-
bilitation should be measured objectively, which is easily done using ambulant
accelerometer based activity monitoring (AM). However a reference database
of AM parameters is currently lacking.
Purpose / Aim of Study:
To collect reference data of objectively measured
PA.
Materials andMethods:
59 Dutch healthy subjects, (37 females) median aged
47.5 (21-66) years with no restrictions in mobility were included. A three-axial
accelerometer was attached during waking hours to the participants’ lateral
thigh for four consecutive days. Data was analysed using previously validated
algorithms in MatLab 7.10.0 ®. Median values of the four days were calculated
and the results were stratified into age groups of decades, 20-29 (30-39) 40-
49 (50-59) and 60-69.
Findings / Results:
Mean measurement time was 13.5 ±1.5 hours per day.
Subjects were sitting median 64 (53) 59 (59) 57 %, standing 22 (32) 29 (26)
31 %, walking 9 (14) 13 (11) 12 % and biking 0.5 (0.4) 0.02 (0.4) 0.5 % of
the day. Subjects walked on average 5217 (8447) 7666 (8474) 7030 steps
per day and performed mean 43 (63) 50 (45) 47 sit to stand transfers a day.
There was a tendency towards the youngest group sitting more and standing
and walking less than the older groups, but no statistically significant differences
were found between the age groups.
Conclusions:
The present data may serve as initial values for a reference da-
tabase. However, the results are affected by a large variation in PA and a small
age range, which might explain the lack of significant differences between age
groups. A larger reference database need to be created where effects of subject
characteristics on PA can be investigated and where people above 66 years are
included as well.
141.
