Gait Lower Extremity Models

Hello there,

I have been modelling some of my gait data with GaitLowerExtremity. In this data set the subject had markers on their toe and heel. I now know this is not sufficient to drive the eversion at the ankle and have therefore added drivers to deal with this.

Unfortunately the model produces extreme muscle overloads. Is this a result of the constraints at the ankles? Are there any strategies I can employ to prevent muscle overloading in this case? I’m interested in getting forces at the joints.

I have attached the model for you to have a look at.

Best regards,


Hi Stephen,

I hope all is well, I am having similar problems with the ankle model, especially from gastroc and soleus. I’ve experiemented with putting a wrapping surface over a common ‘achillies tendon’ and changed the insertion site of the muscles on the calcaneus. It has had a benificial results for many of the models but it needs a little work to be completely robust.

I think a large part of the problem is the single segment foot, creating a large moment arm form toe-off. A throrough check of COP on the end of the foot is another good indiciation at times.

best wishes

Peter (Southampton)

Thanks Peter, I had already thought about changing insertion points but thought this a last resort and hoped there might be something more simple. The wrapping idea is interesting too - I will have to give both these ideas a go.

Have you experimented with different marker sets on the foot to try to overcome your problems?

Best regards,


Yeah, I’ve added fifth met head, navicular, cubiod, and medial cuneiform markers to control inversion/eversion a little better. I don’t think the problem is coming from the kinematics in the foot. When the COP of the force plate reaches the front of the foot during toe-off and the foot is dorsiflexing there seems to be very high recruitment of gastroc. Perhaps a tri-segmental foot might produce more accurate results.

It is a big problem trying to predict knee kinetics, with gastroc contributing significantly to loading. With some work I’ve managed to get toe-off reactions to around 3 times body wieght (heel strike 2.5).

Have you got any ideas on how we can tackle this problem,


A tri-segment foot should help.

Are you modelling gait only? Have you had any more success with activities where the foot remains in contact with the force plate? Sitting/Standing for example.

Hi Stephen,

I am also modelling sit-stand, step descent and lunge. All have there own set of problems, however the ankle/foot tends to play a lesser role in contributing factors.

Hi Stephen,

I had a look at your model, sorry for the long delay. The problem is that the force from the force plate are not applied to the correct foot. In the environment file where the ForcePlatform class is used you have to make a reference to the foot in contact for each platform. There right and left foot are inverted. So that is causing the extreme overloading.
Just switch it around.

Best regards, Sylvain.

even after the force plates are switched onto the correct feet there is still a high peak gastroc/soleus force input on toe-off. Do you have any theories on the problem Sylvain?


We have seen this peak at toe-off in some other gait models. You was discusing about the stiff foot, i think that is one of the factors. As you said a multi segment foot should help on this.
We also made some updates on the leg model recently that seems to help on this case. It will be included in the next repository release.

Best regards, Sylvain.