USING HIP FLEXORS VS. HAMSTRINGS FOR LIFTING THE FOOT FROM SUPPORT IN
RUNNING

Skidd 777, I am flattered by similarities you mentioned between Chi
and Pose. The biggest difference, you think, you see, is that Mr.
Dreyer advocates lifting the leg by using the hip flexors rather than
the hamstrings. Please, get the Chi running DVD and you will be
surprised to see that Mr. Dreyer doesn't "advocate" using hip flexors
anymore, but shows how to lift the heels by flexing knees in air. I
can't imagine how it is supposed to be done by hip flexors. From the
book to the video it is a quite radical shift in "understanding" of
running technique.

Holistic philosophy is not about using the biggest, largest and
strongest muscles to do most of the work and it has never been this
way. Holistic philosophy is about being integrated into the system,
which we call Nature, as a part of it, and use it for our own
perfection. In movement, we interact with gravity as our leading,
predominant force in any movement, and our muscles perform as
transmitters of this force. It is difficult to realize this when your
mind is predisposed to seeing muscles as a primary force in movement
and you rely on them as such completely. It is necessary to take a
step away from your common sense to be able to abstract from "reality"
and see the Hierarchy of Nature.

The Laws of Nature are very simple. Many scientists tried to define
them. One of the first was the French scientist of the 18th century,
P. Mapurtiu, who formulated it as a principle of minimum action. The
essence of it goes as follows: when some change happens in nature, the
amount of action, it takes for this change, is usually the least
possible. At present time this principle received a strong support
from mathematical interpretation and is well known in the theory of
synthesis of technical systems of automatic regulation.

According to this theory, there is no need to use the biggest muscles
to change a position of such a small part of the body, as the foot,
from the ground in running. The primary use of the hamstring muscle
comes from a very specific logic of the running movement. I would like
to emphasize here the word "primary", because strictly speaking, there
is no separate muscle activity in our body, even in some seemingly
isolated movements. There is always some orchestrated effort, a group
of muscles involved in any movement. Therefore, hamstrings represent
the leading group of all muscles engaged in the removal of the support
foot from the ground while the body leans forward during the stance time.

In practice there is no need to ask runners to use the hamstrings, but
just to move the foot from the ground up. The body "knows" by itself
how to do it, but our mind makes it very difficult by "adding" some
core muscle activity to it. That's why I ask to use hamstrings
consciously, in order to distinguish its work from any other muscle
activity. I found through our Pose Tech clinics that most runners have
a perception problem with differentiation between the foot and leg
pull. Instead of pulling or lifting the foot from the ground, they
lift the knee (thigh) by using their hip flexors with a "full
perception" of pulling the foot. Certainly, when you pull the knee,
then the foot would be lifted as well, but it would follow the knee
movement, not the other way around. We need the movement of the foot,
first, as our primary action.

Why is it so important that hamstrings lead in this movement? Because
they initiate and prioritize the foot movement, not the whole leg one.
This reduces the efforts, directs the movement of the foot, and
integrates it correctly with the whole body movement in space and
time. This allows us to bend the knee quicker and rotate the leg
faster, because it becomes a shorter pendulum around the hip axis
(Coriolis Effect) and by this move it faster, forward under the body.
Beside this, the foot pulling action reciprocally initiates the use of
muscle elasticity during the support time.

The whole purpose of pulling the foot under the hip is to bring the
center of mass of the leg to the vertical line going through the
General Center of Mass of the body over the ball of the foot, so that
the body could start falling forward. If the center of mass of the
swing leg is behind the vertical line going through the ball of the
foot, our GCM is behind this line as well. Than our body is not able
to fall or is late to reach the falling point, which is the midstance
or the Running Pose, which we start falling forward from and where the
pulling action starts from, as well. Only when our foot unloads the
body weight, the pulling action can happen. By that time all the front
muscles are silent after being unloaded, so the hamstrings take over
to reproduce the next Pose and the next fall.

How can you learn to differentiate between lifting the leg and lifting
the foot? You need to develop your perception or awareness of your
body. You can perceive it as muscle tension in hip flexors, some
specific positions of the knee, thigh and foot during the swing time
of the leg. You can easily distinguish between these leading
activities by watching your run on the video. If you are not using the
foot pulling action, your foot is lagging behind. Using hip flexors
leads to an excessive hip transverse rotation and higher than
necessary thigh position in the front part of the leg swing. In the
proper foot pull, neither one of these actions is present.

One note about the use of hip flexors in cycling. There is no need to
use them as primary muscle force in upward pedal stroke, but I'll
leave it as a separate topic for another discussion.

Dr. Romanov