The Real Paradox of the Extensor Paradox
Considering the running motion, we already know that maximum quadriceps muscle activity occurs at the transition between knee flexion and extension and coincides with maximum vertical ground reaction force. After this, knee extensor muscle activity starts to diminish and ends almost entirely just as leg extension begins. So as the leg is rapidly extending, the leg extensor muscles are silent. This is the extensor paradox mentioned earlier.
What this tells us is that the concept of running as a push–off movement, which at first glance would seem quite “logical,” is shown in these studies to be obviously wrong. But let’s not call it a “paradox.” It’s really just a misunderstanding. As science has shown, the exact muscles that are thought to be working during this supposed “push–off” are in fact silent.
The first reaction about this misunderstanding might be a yawning “so what.” After all, what difference could it possibly make whether or not certain muscles are working or whether or not a runner actually initiates the running movement by attempting to push–off?
Wrong thoughts + wrong action = wasted time
The problem stems from this misguided thinking. If a runner even thinks about pushing off, much less tries to do it, not only is he wasting energy in the attempt to flex muscles that are not in a position to be flexed, but more importantly he postpones the work of the muscles that are supposed to be working in a coordinated fashion. Specifically, the push off attempt will delay the work of the hamstrings to pull the foot from the ground at a very specific time.
The lack of understanding about what is really happening in the running stride means that the runner ends up wasting time — and time is the ultimate measure of success in competition. Trying to push off instead of focusing on simply pulling the foot from the ground literally amounts to working against oneself. It may seem a small thing, but it is precisely the small things that are the basis of perfect running technique.
As an example, when you are on a bicycle going down a very steep hill and you try to pedal, your efforts are absolutely empty — and wasted. The power of gravity is overwhelmingly higher than the power of your muscles to drive the pedals. The same thing is true when you try to contract muscles that are supposed to be “off” in a specific point in the running stride. It is a complete waste to try and work muscles that don’t need to be worked.
It is necessary to understand that we have two distinguished types of muscular activity — voluntary and involuntary — and that there are big differences between the two. Involuntary muscle activity takes place as a reaction to gravity, to changing direction of the body, to losing balance etc. All involuntary muscle activity is reactive; you don’t need to control it at all. Landing activity is also involuntary.
On the other hand voluntary muscle activity is mostly related with specific goal–oriented movements such as touching, bending, swinging etc. These movements occur as a result of a conscious decision, in the case of running the decision to pull the foot from the ground. Of course even here we’d like to transition these conscious movements to the sub–conscious. The goal would be to perfect these specific movements so that it becomes second nature to do them properly, without active thought.
You could equate this to the advanced state of performance of a martial arts fighter, a “Zen–like” state where we are able to perform conscious movement unconsciously. In such a state the mind is not disturbed by anything — you think nothing but are ready to do anything. In running we have only one point where we need to perform a conscious activity — pulling the foot from the ground.
Wrong action = increased workload of the muscles
The problem is that most runners constantly confuse the distinction between the types of muscle activity and attempt voluntary activity where involuntary activity is already taking place. This confusion substantially increases the workload of the muscles resulting in an excess of muscle tension. This is the real paradox of running. If you earnestly try to do something but it happens to be the wrong thing, you are both wasting energy and working against the technique that would give you the best results.
We must be absolutely clear as to how to perform a voluntary movement, but not create pointless voluntary muscle activity. Voluntary movement does not equal voluntary contraction. You can command your body to perform a specific action, but you can’t tell it which specific muscles it needs to use in the action. Your muscles will work it out.
You shouldn’t even attempt to tell your muscles how fast or forcefully to contract. The intricate communication between the brain and the muscle groups handle these decisions. We can command which movements to produce and only this, nothing more. The actual recruitment of muscles to perform the desired action is done according to the present state of the body and its ongoing movements.
Which kind of simplifies things nicely doesn’t it? As an athlete, the only thing you need to know is which movements to produce, not how to produce them. You need to know that you must pull your foot from the ground, but need not concern yourself with what muscles. Just that it needs to be done and done right–on–time. The drills in the video series will help you refine this skill of using your body correctly during running.
- Siff, M. Biomechanical foundations of Strength and power training. In Biomechanics in Sport London. V. Zatsiorsky Editor. Blackwell Scientific Ltd., 2000, pp. 103–142.
- McClay, Lake, and Cavanagh. Muscle activity in Running. Biomechanics of distance running. P.R. Cavanagh, Editor. Champaign: Human Kinetics, 1990, pp. 165–185.
- Brandell, B.R. An analysis of muscle coordination in walking and running gaits. Medicine and Sport: Biomechanics 111 S. Cerquiglini, A. Venerando and J. Wartenweiler. Basel, Editors. Switzerland: Karger, 1973, pp. 278–287.
- Nilsson, J. and A. Thorstensson. Adaptability in frequency and amplitude of leg movements during locomotion at different speeds. 10th International Congress of Biomechanics Abstract Book, 20. Solna, Sweden: Arbetar–Skydd Sverket, 1985, p. 194.
- Mann, R.A. and J. Hagy. Biomechanics of walking, running and sprinting. American Journal Sports Medicine, Vol. 8, 1980, pp. 345–9.1. 2. 3. 4. 5.
- Paré, Stern, and Schwartz. Functional differentiation with the tensor fasciae latae. Journal of Bone and Joint Surgery, Vol. 63, 1981, pp. 1457–1471.
- Schwab, Moynes, Jobe, and Perry. Lower extremity electromyographic analysis of running gait. Clinical Orthopaedics, Vol. 176, 1983, pp. 166–170.
- Montgomery, Pink, and Perry, Electromyographic analysis of hip and knee musculature during running. American Journal of Sports Medicine, Vol. 22, 1994, pp. 272–278.
- Wank, Frick, and Schmidtbliecher, Kinematics and electromyography of lower limb muscles in overground and treadmill running. International Journal of Sports Medicine, Vol. 19, 1998, pp. 455–461.
- Elliot, B.C. and B.A. Blanksby. The synchronisation of muscle activity and body segment movements during a running cycle. Medicine and Science in Sports, Vol. 11, 1979, pp. 322–327.
- Mann, Moran, and Dougherty. Comparative electromyography of the lower extremity in jogging, running and sprinting. American Journal Sports Medicine, Vol. 14, 1986, pp. 501–510.
- Heise, Morgan, Hough, and Craib, Relationships between running economy and temporal EMG characteristics of bi–articular leg muscles. International Journal of Sports Medicine, Vol. 17, 1996, pp. 128–133.
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