By Al Taylor (a.k.a. Mr. Rhonda), Senior Staff Columnist
Understanding how the legs work clarifies the principles of the study of human motion by knowing why these principles are so important.
All living creatures have a brain and a central nervous system to control their body functions. Nothing happens within their body without the brain giving its okay. Few people realize the human leg and foot have a second controller, so to speak. Its ability to control is nothing like that of the brain. However, it does control how the leg/foot will move, no matter what the brain tells it to do. The name of this controller of leg/foot movement is the ankle.
Observing the legs during the act of skating, walking, running, jumping, landing, etc., seems like a pretty simple action. But make no mistake; each of these movements is a highly complex motion.
The extension of the leg requires coordinated movement of the hip, knee and ankle, along with the simultaneous coordinated movement of the foot, which involves the ankle, hindfoot, midfoot and forefoot. Of significant importance: each joint of the leg and foot must move through their full respective range of motion. And, each joint must reach the limit of its range at the exact moment the leg is fully extended. Failure to do so will leave a bend in the leg at the knee. All skaters, wearing conventional hockey skates, experience this phenomenon.
The foot is incredibly complex in its structure and function. The basic structure of the foot contains three main parts, namely the forefoot, the midfoot and the hindfoot.
The forefoot comprises the area from the ball of the foot to the end of the toes. This part of the foot is capable of two movements: that of up and down or dorsiflexion and plantar flexion. This up and down greatly enhances the strength and speed of leg extension the moment the leg is fully extended. Plantar Flexion movement of the foot is only possible if there is a coincidental movement of the ankle to transfer of body weight on the heel to the ball of the foot. The transfer of body weight is a staggering important 'why.'
The midfoot is located between the hindfoot and the forefoot. The longitudinal and transverse arches of the midfoot distribute the body weight efficiently across the entire foot and act as a spring to absorb and release the force of the body’s weight on the ground or a surface such as the ice of an arena. It is significant to note, that balance comes from the midfoot. Standing on one leg and watching your foot you can see proof of this statement. It soon becomes apparent the foot is making a series of muscle twitches to ensure your centre of gravity remains over the body’s base of support.
The bones of the arches also act as a lever to increase the strength of the muscles acting on the ankle joint, allowing the body to easily lift its entire weight up on the forefoot. This leverage of the forefoot is essential to rapid movement and jumping because the midfoot causes an incredible increase in the strength and speed of the leg extension through plantar flexion of the toes.
The hindfoot extends from the heel to the midfoot. The purpose of the hindfoot is to trigger the midfoot to apply leverage to the bones of the forefoot. The ankle is really a hinged joint located between the bottom of the leg at the tibia and the top of the heel bone. The almost square shape of the top bone of the ankle only allows the ankle two movements. The strongest movement that of up and down, has the greatest range of motion. During vertical movement, the ankle actually changes its size. The movement up is called dorsiflexion. The movement down is called plantar flexion. Dorsiflexion causes the ankle to grow in size. Plantar flexion causes the ankle to decrease in size. The other movement, that of side to side, is the relatively weak movement of rolling to the outside (rollout) is called supination and has a very limited range of motion. The ankle has virtually no provision for movement to the inside (roll-in) and is called pronation.
However, there is a huge red flag associated with the combined up and down motions of the ankle and forefoot. If the hindfoot and the forefoot are weight-bearing on the same plane, namely the sole of the skate boot, plantar flexion of the forefoot cannot occur. In fact, it is impossible. The result is a bend in the push leg at the knee.
Experience your ankle’s ability to decrease or increase in size. Sit down and place one foot over the lower thigh area of the other leg. Loosely grip the front and back of the ankle just slightly below the knobs of the ankle with the fingers and thumb of both hands. Rotate your ankle and toes up towards the knee. You can feel your ankle getting bigger. The ankle’s range of motion is 20° above the neutral position of the ankle. Dorsiflexion is all about enhancing performance. The neutral position is where the foot and the lower leg form a 90º angle.
Now, rotate your ankle and toes in a downward direction away from the knee. You can feel your ankle getting smaller. The ankle’s range of motion is 40° below the neutral position of the ankle. Plantar flexion is all about generating momentum.
If the ankle did not move, you were not squeezing hard enough, or your ankle muscles are stronger than those of your hand. Perhaps you will have to get someone with stronger hands to help you feel this sensation of immobility.
Here is a demonstration to show what happens when the ankle cannot change its size at will. This is a real revelation to those who tape their skates to their ankles and/or lace their skates to the top eyelet of the skate boot and then they may wrap the excess lace length securely around the top of the skate boot.
Have a volunteer remove their shoes and walk back and forth in their stocking feet. This allows the observers to see, and the volunteer to feel, the ease of movement. Next, have the volunteer sit down and take off their socks. The demonstrator should apply some ankle wrap around the ankle area to protect the skin and body hair from the next step. Have the volunteer point their toes downward because that is how most skaters tighten their skates. Now, proceed to tape the ankle tightly from just below the knobs of the ankle to a point about four inches up the lower leg. Repeat the procedure for the other ankle. Have the volunteer put their socks back on and walk around just as before. It is immediately evident to all, including the volunteer; there is a major loss of mobility and performance. The volunteer has difficulty getting out of the chair and their ability to walk is similar to that of a toddler walking with a full diaper. The volunteer has more difficulty returning to the chair and trying to sit.
It is obvious the taping restricted ankle movement. The volunteer’s inability to first lean forward prevents ease of movement.
During the skating action, the hip, knee, ankle and foot joints all rotate together in a coordinated manner. Each joint has its own natural range of motion and each move through their respective range of motion at the same time. When all of the joints simultaneously reach the end of their range of motion, the leg should be straight and the knee flattened.
More on the Science of Skating coming from OFFSIDE Coach Al soon!