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Dear BIOMCH-L s:
I mailed a message a few days ago regarding what appeared to me
to be two contradictory results related to human locomotion. The first was
about the effect of slope on the stride length and the second involved the
relationship between the stride length and the speed of walking.
As some netters pointed out, the first contradiction is not a contradiction!
In fact I made two mistakes. First, I assumed that the stride length for
running and for walking will be similarly modified by slope; there is no
reason for this to be necessarily true. Second, I misinterpreted a 10% gradient
(mentioned in Paper#2) to be +/- 10%, whereas the author really meant a +10%.
Thus Paper#2 actually agrees with Paper#1.
Result: For walking, mild uphills have no significant effect on the
stride length, whereas mild downhills shorten the stride length significantly.
On the other hand downhill running produces longest strides and uphill
running produces shortest strides.
Is it at all possible to predict the variation of stride length with slope?
Given the work on passive locomotion models (Inman?) it seems that the
relationship might not be too complicated (My intuition could be totally
wrong though!).
Thanks to all the netters who wrote to me. I will respond to some of
you individually.
The second contradiction still stands! One netter (TURN_KNICK@hrz.dshs-koeln.de)
mentioned that a book by Vladimir Zaciorskji reports nonlinear relationships
between stride length and velocity. I will wait for other responses. Finally,
I quote a second explanation (from hl@SysCon.uu.se), which appears to be quite
reasonable:
"Concerning your second question, Q2, I have the following comment:
It it established, (see for instance the work by Larry Lamoreux, I do not
have the exact reference at hand), that the strategy for increasing the
walking speed for normals, is to increase both cadence (steps/min) and step
length (m). Since speed in the product of step length and cadence, the speed
of walking would be a linear function of step length only if the cadence
were constant."
"Assuming that the cadence is varying linearly with step length (which seems
to be approximately valid), it is therefore to be expected that the walking
speed is quadratically depending on the stride length (or step length), The
same relationship also holds for the relation between speed of walking and
cadence."
"This relationship is only valid for small variations around the normal speed
of walking for a specific subject, and for subject with disabilities in the
locomotor system, it is not generally valid. If there is a decreased joint
mobility for instance, it might be impossible to increase the step length,
and the speed of walking will now be linearly depending on cadence."
Thanks
Ambarish Goswami
I mailed a message a few days ago regarding what appeared to me
to be two contradictory results related to human locomotion. The first was
about the effect of slope on the stride length and the second involved the
relationship between the stride length and the speed of walking.
As some netters pointed out, the first contradiction is not a contradiction!
In fact I made two mistakes. First, I assumed that the stride length for
running and for walking will be similarly modified by slope; there is no
reason for this to be necessarily true. Second, I misinterpreted a 10% gradient
(mentioned in Paper#2) to be +/- 10%, whereas the author really meant a +10%.
Thus Paper#2 actually agrees with Paper#1.
Result: For walking, mild uphills have no significant effect on the
stride length, whereas mild downhills shorten the stride length significantly.
On the other hand downhill running produces longest strides and uphill
running produces shortest strides.
Is it at all possible to predict the variation of stride length with slope?
Given the work on passive locomotion models (Inman?) it seems that the
relationship might not be too complicated (My intuition could be totally
wrong though!).
Thanks to all the netters who wrote to me. I will respond to some of
you individually.
The second contradiction still stands! One netter (TURN_KNICK@hrz.dshs-koeln.de)
mentioned that a book by Vladimir Zaciorskji reports nonlinear relationships
between stride length and velocity. I will wait for other responses. Finally,
I quote a second explanation (from hl@SysCon.uu.se), which appears to be quite
reasonable:
"Concerning your second question, Q2, I have the following comment:
It it established, (see for instance the work by Larry Lamoreux, I do not
have the exact reference at hand), that the strategy for increasing the
walking speed for normals, is to increase both cadence (steps/min) and step
length (m). Since speed in the product of step length and cadence, the speed
of walking would be a linear function of step length only if the cadence
were constant."
"Assuming that the cadence is varying linearly with step length (which seems
to be approximately valid), it is therefore to be expected that the walking
speed is quadratically depending on the stride length (or step length), The
same relationship also holds for the relation between speed of walking and
cadence."
"This relationship is only valid for small variations around the normal speed
of walking for a specific subject, and for subject with disabilities in the
locomotor system, it is not generally valid. If there is a decreased joint
mobility for instance, it might be impossible to increase the step length,
and the speed of walking will now be linearly depending on cadence."
Thanks
Ambarish Goswami