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Thankyou to everybody who replied to my search for normative angular
velocity data. It appears that no-body has any such data!! Chris Kirtley
suggests why:
No - I have never seen any normative data on joint velocity (and I have
looked many times!). There are some methodological problems which I suspect
may be the reason why. To get velocity you need to run a derivative
algorithm - usually a difference equation followed by a filter, because
differentiation inevitably amplifies any high-frequency noise in the signalThe end result will be very dependant on what cutoff frequency you use for
the filter - a lower cutoff will reduce the velocity recorded, while a
higher cutoff will let through high frequency noise. Choosing the cutoff
is a bit subjective and empirical.
Thanks again.
Johanna Robertson
Physiotherapist, MSc
Movement Analysis Lab
Hôpital Poincaré
Garches, France.
velocity data. It appears that no-body has any such data!! Chris Kirtley
suggests why:
No - I have never seen any normative data on joint velocity (and I have
looked many times!). There are some methodological problems which I suspect
may be the reason why. To get velocity you need to run a derivative
algorithm - usually a difference equation followed by a filter, because
differentiation inevitably amplifies any high-frequency noise in the signalThe end result will be very dependant on what cutoff frequency you use for
the filter - a lower cutoff will reduce the velocity recorded, while a
higher cutoff will let through high frequency noise. Choosing the cutoff
is a bit subjective and empirical.
Thanks again.
Johanna Robertson
Physiotherapist, MSc
Movement Analysis Lab
Hôpital Poincaré
Garches, France.