Dear Colleagues,

Thanks to the many responders! Following is a quick summary of replies...

The original question was:
In analysis of lower extremity biomechanics it is common to assume 1e6
gait cycles per year. I have many papers in which this number is noted. It
seems to have become so common that authors in recent literature no
longer provide reference for the number. Would you please remind me of the
early reference for this assumption?

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The winning response in the humor category...
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I was in NYC this weekend. On the subway, I noticed an ad for Dr. Shoals or
something which proclaimed that "the average foot takes 10,000 steps per
day". Or 3.5 million/year. I was skeptical, though I don't think this
considers elderly and/or THR patients.

Shoals, Dr. "The average foot takes 10,000 steps per day": Uptown 6 Train.
2002 Nov 23.
-------------------
Other references...
-------------------
Wallbridge N, Dowson D."The walking activity of patients with artificial
hip joints" J Engineering in Medicine 1982 11:95-96

Schmalzried TP, Szuszczewicz ES, Northfield MR, Akizuki KH, Frankel RE,
Belcher G,
Amstutz HC. Quantitative assessment of walking activity after total hip
or knee replacement. JBJS. 1998 80-A:54-59.

Silva M, Shepherd EF, Jackson WO, Dorey FJ, Schmalzried TP.
Average patient walking activity approaches 2 million cycles per year:
pedometers under-record walking activity.
J Arthroplasty. 2002 Sep;17(6):693-7.

Work by Don Kettelkamp in the early to mid 70's

1Mcycles per year is probably an underestimate, if you take into
account **ALL** activities (i.e. including gait, small steps in
indoor activities, a.s.o.) of an active subject. The most recent
estimates I am aware of are those of Morlock et al, published on
J.Biomech in 2001.

Seedhom et al., Wear 24:35-51, 1973


Thanks very much to all who responded!

Tony Petrella

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