# Thread: Centripedal forces and the calf muscle pump

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Dec 2015
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Wilton Street Glasgow
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## Re: Centripedal forces and the calf muscle pump

Many thanks for the above .

During gait on a running track ,the foot undergoes periods of rapid acceleration ,even more rapid deceleration and not moving at all if we take the track as a reference point .

For example let's say we take an individual walking at 1.5 m /s . That is to say the persons COM is moving at 1.5 m/s relative to the track . The standing leg (reference leg )will be on the track and not moving at all so we have a "velocity gradient" along the length of the leg as the body moves forwards .

So now let's say the swing foot touches down on the track and the reference foot starts to clears the track .
The reference foot was moving at 0m/s but must quickly accelerate to catch and pass the body . So let's say it goes from zero to 3m/s in a third of a second . This acceleration of the reference leg and foot is likely to generate substantial centripedal forces and centrifugal affect making venous return more difficult than if it were merely against gravity .

So the reference foot now comes past the body and just as it touches the ground , it decelerates very rapidly to zero ,and then to 1.5 m/s in the opposite direction to the COM so again we have higher centripedal effect .

I don't have the maths to work this all out so resorted a bottle of HP sauce strapped to my ankle .

. In a quite part of Glasgow I then walked a number of steps and found that the thick sauce did indeed flow much more rapidly out of the bottle during the swing phase of gait and at the end of the swing phase in particular ,as the foot rapidly decelerates . (It should be noted that even although the now track bound foot is not moving relative to the track it is moving at 1.5m/s relative to the body and so centripedal forces are still being generated )

I do not recommend this experiment at all as it causes a real mess ,there is a danger of slipping on the sauce and my training shoes are now in the bin .

Ton , could you once again put some figures on the above ? It may be that the way venous return is viewed needs to be changed .

Gerry
Last edited by Gerrard Farrell; 02-08-2019 at 07:56 AM.