Leg press i think is an example of closed kinematic chain exercise as the foot is fixed and the distal move to the proximal while exercising

Hi. Mr. Ponmathi Paramanandam.

in other hand if we imagine that the fixed one is the limb that attached to the ground so the upper part of the leg is fixed and the feet and the shank is freely moving that make this apparent which this movement is open kinetic chain exercise. although your answer is correct too. according to the articles:

there are contradictions in the definition of kinetic chain terminology (Ellenbecker & Davies, 2001). so for inference such a ambiguity there should be another definition or a good reason exist for accepting that leg press is sitting in which form of exercise.

with regard.

Doesn't this depend on the leg press machine you are using? I guess there is a difference between the ones where the feet move (=open chain) and the others where the feet are fixed and the torso and upper body move (=closed chain).

Hi Mr. Matthieu Boisgontier

I get your definition of close/ open kinetic chain exercises but the problem is pertaining to the type of exercise we discussed. According to your definition you ‘ve brought here if the load is on the limb and overcome by it, this is an open kinetic chain exercise but for the leg press that I put the picture below even though the athlete overcome the load he himself use a GRF for pushing the bar from the ground. Actually if upper part of his leg doesn’t attached to the ground he couldn’t push the load to overcome it according to the Newton’s third law. So the athlete use both push of his leg to overcome the bar or use GRF of the ground for overcoming the bar.

thus my question is remain that this type of exercise is close or open kinetic chain?

thanks for reply.

with regard.

Here the foot is fixed to the machine,foot meets resistance,resulting in predominant concentric contraction of hip and knee extensors giving a a closed kinetic chain exercise

in a closed kinetic chain exercise

1.there is interdependence of joint motion(here,knee flexion depend on ankle dorsiflexion)

2.motion occuring proximal and distal to the axis in a apredictable fashion(here knee flexion is accompained by hip flexion,adduction,internal rotation and foot dorsiflexion)

3.Greater joint compressive force

4.stabilisation by joint congruency

The above criteria is met in the above exercise ,hence it is a closed kinetic chain exercise.To promote a true closed state,ask the indivual to stay down,and again in the picture the man is holding with hands that gives that the upper body is stabilised

Dear Mohsen,

An interesting debate. I would consider this exercise an open kinetic chain exercise as the distal segment (although attached to a platform – which is moving) is moving around/away from the proximal segment. A squat or push up for example has the proximal segment moving around the distal segment. In saying this there are also kinetic link or pseudo-chain movements that have both occurring at the same time - a push press exercise for example has the lower body performing a closed kinetic chain exercise while the upperbody is performing an open kinetic chain exercise. I would urge against trying to tie in joint compression into the mechanical term as this can be misleading. Consider a chin up...this exercise has a joint distraction but is closed kinetic chain as the proximal segment is moving around the distal segment. Likewise zero gravity conditioning (like that required for astronauts) adds a new dimension.

Just to mix it up a little further, the concept of kinetic chains is an engineering one that is attributed to a mechanical engineer named Franz Reuleaux (circa 1875) who describes a series of overlapping segments connected via pin joints. These interlocking joints would create a system that would allow the movement of one joint to affect the movement of another joint within the kinetic link (hence the term of a kinetic link exercises which has two compound movements joined together – push press, baseball pitch, etc)

Regards

Rob

In my idea Squat and Push up are like together and both of them are CKC, and in another hand Leg press and Bench press are same and are OKC, just in lower and upper extrimity are diffrent.

A similar comparison (bench  press with proximal fixation vs push-up with distal fixation) has been studied with EMG:

Blackard D. Use of EMG analysis in challenging kinetic chain terminology. Medicine and science in sports and exercise. 1999-03;31:443-448.

In that study, it turns out that the neural control of the movement (as indicated by the final common output of the motor system) is the same regardless of which end of the limb is fixed and which is free.  In other words, the nervous system doesn't care which end is fixed or free when executing limb movements with similar kinematics and similar loads, so the functional importance of the whole "open vs closed chain" debate seems to be in question.  

As far as I know, in literature, all types of leg press are classified as a closed kinematic chain exercise.