I apologize up front for not being able to be very specific. I worked with these on my MS Thesis but I have not used nor had access to them in over a year.

We initially set up the parameters in the computer program. Then upon data collection we totaled the times of vigorous vs moderate vs light and then subtracted out the light activity to find the participant's actual time in this parameter. Again we initially set up the parameters and set up the system to acknowledge when there was No vs Light activity. In short, it all came down to messing with the computer analysis program prior to activating the actual unit itself.

Secondly- no we always had our Participants wear their units on their hip. However we did have the participant also wear a FitBit unit (which can be worn practically anywhere on the body) and verified this data against the actigraph data. The comparison did give significantly comparible results for each unit.

Hope this helps.

Hi Paul,

I have used the actigraph both in my master thesis and my current PhD project to measure different types of activity (lying, sitting, standing still, moving, walking, walking stairs, running and cycling - all validated). Our focus has not been on the energy expenditure but instead on the frequency, duration and intensity of the exact movements the participant has been doing. This is based on two actigraphs placed on the hip and the thigh for 4-6 consecutive days. By placing the Actigraphs on the thigh and on the hip, we are able to distinguish between the activities that otherwise usualy are categorized as sedentary: lying, sitting and standing still.

I have not tried to measure activity by wrist worn accelerometers, but anyway I hope my answer is helpfull to you.

Best regards

Julie

Article Comparison of Objectively Measured and Self-reported Time Sp...

Hi Paul,

We published on this topic in younger adults (not older adults), comparing wrist and waist outputs at slow, medium and fast self-selected walking speeds.

You can see our results here: http://digitalcommons.wku.edu/cgi/viewcontent.cgi?article=1500&context=ijes

Hope this is useful.

David

Hi Paul,

if you wnt to measure physical activity with low intensity and low frequency, you have to be aware that there is strong non-linear frequency response of the ActiGraph that leads to an underestimation of activities with low frequency as well as with high frequency.

Best regards

Stefan

Thanks, David for the link to your paper.  And Stefan, thank you for this - we are aware of the issues with underestimation and are trying to work through those.

Best, Paul

Dear Paul,

if you want to avoid the understimation of this device, try to use a sensor with a more linear frequency response. You can have a look at the devices from movisens (www.movisens.com)

Best regards

Stefan