Posted: July 6, 2006

Athletics: Running Economy

From Noakes, Lore of Running

“The authors concluded that a high VO2-max (anything above 67 mlO2 per kg per min.) helped each athlete gain membership of this elite performance group. Within this select group, however, running economy and not VO2-max was the factor controlling success in the 10-km race.”

Making more efficient use of your energy using a good running technique

When using a correct running technique, less energy will be needed to maintain a certain tempo. You will be able to run more easily and economically. When your muscles know exactly how to work, then the motion of running will require much less energy. Novice runners experience this more than anyone. In the beginning, the body needs much more energy than after a few weeks. However, even directly at the start, you should know where to direct your attention for a good running technique.

Experienced runners can even improve their performance by focusing on technique during training. Of course their technique will not progress as spectacularly as that of a new runner, but change will occur to such an extent that performance can be improved without running more kilometers. Furthermore, continuing to maintain an efficient technique during training is important.

In summary, technique is an essential component of training, both for the novice as well as for the experienced runner. Namely, it will determine to an important degree a runner’s performance.

A good running technique is the best means of preventing injury !!

Injury due to strain is the greatest threat to a runner. Some good examples are complaints in the Achilles’ tendon, lower leg and knee. The chance that such injuries will occur decreases when a technique is performed better. From this viewpoint, every runner can benefit from a training which focuses on improving technique. During running, the muscles, tendons and joints undergo great stress. Every landing taxes the ankles, knees, hips and back. An individual will land 2000 to 2500 times on each leg when running 10 km. When a technique is executed incorrectly, then repeated strain on the muscles and tendons, for example, can become so great that injury results. Running is a cyclical motion which means that a fixed pattern of movements is repeated. Even a minor error occurring within the cycle can be consequential because the cycle is repeated thousands of times, for example when running 10 km.

The enjoyment of running can quickly be spoilt by injury due to strain resulting from a faulty technique. Every runner who wants to decrease the threat of injury will be advised to consider technique as an important component of training.

It’s more than only energy-generating processes …

Processes which generate energy play a principal role during running. Long-distance runners generate the most energy by burning fats and carbohydrates. Anaerobic energy processes such as glycolysis are most dominant in sprinters. The generation of metabolic energy is served by the resynthesis of ATP from ADP. Traditionally, much attention is paid during training on how to optimalize energy-generating processes. Training is aimed at increasing the supplies of energy-rich substrates, on one hand, and at increasing the speed at which energy can be released, on the other hand.

Nevertheless, even if two athletes are able to generate equal amounts of force, their running speeds still might differ. The opposite may also be true – that two runners might clock the same time across 5 kilometers while generating different amounts of energy. The reason for this can be traced back to differences in running economy or, in other words, whether a runner’s technique is energy-efficient and therefore whether available energy is used sparingly.

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The same running speed can be realised using different amounts of energy

The secret behind Running Economy

Jung , 2003 (review)
Ä key component to running economy is the ability to store and recover elastic energy from the eccentric contraction”

The largest portion of the force generated to run will be used to perform two important partial movements.

First, recall vertical displacement or the up- and downward oscillation of the body.

Second, recall how the leg is swung back and forth as it accelerates and slows down. During the motion of running, the legs are constantly oscillating up and down. However, man is not built to be an expert at running. There is a relatively large amount of mass in his legs which requires a great deal of energy to move. In animals of flight, more mass is located near the pivotal point or hip while very little mass is located near the extremities (Alexander , Principles of Animal Locomotion). This makes these animals well adapted for running energy-efficiently.

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two important partial movements

To guarantee that a running pattern is efficient, both partial movements must be accurately coordinated to work together. When energy is saved by limiting vertical displacement, then more energy must be invested in accelerating and slowing down the legs as they swing back and forth.

This works as follows: Moving the legs up and down as they swing back and forth uses no less than 80% of the total energy needed to run. The larger the range of movement, the more energy that will be required to move the legs.

When there is less vertical displacement, the floating phase or time in mid-air will be shorter and the pace will have to quicken. This means that while limiting the body’s vertical displacement will save some energy it will also result in a much higher expenditure of energy to perform other movements, such as accelerating and slowing down the legs. This is why limiting the amount of energy spent for one movement will not necessarily prove to be economically efficient.

Good runners clearly move their bodies vertically when the frequency of their pace is low, and they stay longer in mid-air. This pattern is advantageous because the rhythm of the legs is lower and the range in which they swing back and forth is smaller. In other words, the knee is not lifted too high and the support leg leaves the ground rapidly at the end of stance – even before the knee is completely extended. In this way, a runner can save a substantial amount of energy generally needed for the energy-consuming acceleration and slowing down of the legs as they swing.

After analyzing the play of forces occurring during push-off, it appears that the direction of force during push-off is mainly vertical. The vertical component has been measured to be about 7 times greater than the horizontal component of push-off.

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The push off is mainly in a vertical direction

The energy invested in vertical displacement will not be completely lost. Some of this energy can be reused because it can be stored temporarily in the elastic structures of muscle. Thereafter, stored elastic energy can be unloaded and contribute to the power needed for the next pace.

Tendons are excellent springs (Ker (1981) J. Exp. Biol. 93:283)
They can be stretched by about 10% and in their elastic recoil return 93% of the work done stretching them.

A good illustration here is the action of calf muscle. At the beginning of the landing, elastic segments in calf muscle are stretched. In particular, much elastic energy is temporarily store in the Achilles tendon before being released during the next pace. This type of muscle action is called reactivity. If reactivity is used well, then an important portion of the energy invested in vertical displacement can be used again. The foot can also help to reuse elastic energy. During the first part of the landing, the foot’s shape deforms so it can function as a springboard.

Ker, Bennett, Bibby, Kester & Alexander (1987).
The spring in the arch of the human foot. Nature 325:147-9

Together with the elastic action of calf muscle, already 50% of the energy needed for vertical displacement can be reused. There are even more elastic structures within the body which can contribute in this manner. Some examples are the hamstrings and tractus iliotibialis. When the pelvis rotates around the saggital axis, the tractus iliotibialis can transform elastic energy into energy needed to raise the body’s center of mass.

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All muscles below the knee and the structure of the foot, work together as a efficient elastic spring.

Ker, Bennett, Bibby, Kester & Alexander (1987).
The spring in the arch of the human foot. Nature 325:147-9
A 70kg man running at 4.5m/s exerts a peak ground force of 2000 newtons. He loses and regains 100 joules (KE + PE) in each step.

	energy (J)	% return
Achilles tendon	35	93
Arch of foot	17	78
Running shoes	6-8	54-66
Harvard track	7	90

Being able to work optimally with reactive muscle action places a heavy demand upon the body’s coordination. An efficient running technique does not simply arise out of the blue but rather requires much training instruction. Even a good runner must continuously practice to maintain his technique.

For reactive muscle action to work optimally, tension must already be present in the support leg upon landing. Then the elastic muscle segments can be loaded better during the landing. The contractile segment of muscle is responsible for loading elastic segments. In addition, the ground contact time must be kept brief because energy can only remain in elastic segments for a short time. The foot should be placed as well as possible directly beneath the hip. Landing on the heel is not compatible with reactivity. To keep ground contact short, the heel must leave the surface rapidly. Together, brief ground contact and sufficient vertical displacement will help to save energy optimally during both energy-consuming partial movements.

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Tension in lower leg and foot muscles prior to foot placement

The basis for energy-efficient running is to maintain brief contact with the ground and prolong the floating phase.

Running DVD
In this DVD, a running technique is presented based on the application of knowledge gained from anatomy and biomechanics. Namely, in order to learn more about a running technique, having insight into how different muscles work during running is essential. Only observing how the arms and legs move during running will provide insufficient information. One can only gain insight into the complexity of running if one understands how muscles work together as well as alone. In addition to showing how different joints can move, extensive information will be given on the structure and function of the most important muscles. Attention will be placed, for example, on variations in muscle morphology, types of muscles function and how the most prominent muscles work during running.

Furthermore, building upon this, when describing the running technique, attention will be paid to topics such as start and acceleration, high-speed and efficient running. The latter can be equated with constant ‘low’-speed running such as in the case of long-distance runners.

Two characteristic partial movements can be differentiated within the cyclical pattern of running: i.e., the up- and downward movements of the legs and vertical displacement of the body. It will be shown that an efficient technique will require that both components be optimally tuned to function together. However, such fine-tuning will place specific demands on the position and movement of the trunk, arms, pelvis and legs. The complex combined action between the trunk, arms, pelvis and legs during running will be described in detail.

An optimal running technique can only be achieved after thorough training. In order to give responsible instructions regarding technique during training, more than 100 technical exercises have been included. Moreover, several tens of analyses of running patterns for both recreational and performance runners are provided. After analysis, errors will be directly linked to relevant exercises useful for improving technique.

Training (DVD Running is based on the book Running from Bosch & Klomp)
Great coaches have worked extremely hard to help an athlete master a skill, with little, or no, results. Then one day the coach says something in a way and the athlete “gets it” right away.
That same athlete often remarks: “Why didn’t you tell me that years ago? It’s so simple!”

In this DVD, (www.runningdvd.com) the authors have attempted to show clearly that training technique should be given a prominent place within the total training program. Training technique is not only to be recommended for sprinters or competitive middle- and long-distance runners. Even recreational runners can increase their pleasure in running by systematically training their technique. In addition to being a factor which affects performance, a good running technique will also help to prevent injury. It is therefore important to adhere to a number of guidelines when training.

Training technique will have the greatest effect when the runner is not fatigued. Therefore this component should be scheduled at the beginning of a training, for example directly following warm-up.

If an individual has had little experience with running instruction, a cautious start is recommended. One can begin with a 10-15 minute instruction of technique. The choice of exercises should be limited to those which are simple and basic. Just as for other types of training, one can apply the same training principles in order to design instruction. In the beginning, much stress will be experienced namely by the calf muscles and hamstrings so that enough time must be allotted within the program to train technique gradually. This also applies when new exercises are introduced.

One can begin by training once weekly. Optimal effects can be observed when training 2-3 times weekly. One must work not only to improve but also to maintain a running technique. It is a simple fact that a running technique needs constant upkeep. If a technique is to function optimally, then movements must be timed precisely, i.e., a fact which forces even the best elite runners to devote time and attention to training technique.

About the authors

Frans Bosch

Bosch trains top athletes, jumpers and sprinters, among whom the high-jumpers Wilbert Pennings and Tora Harris are the most well known. He is the national coach teaching jumping at the Koninklijke Nederlandse Atletiek Unie (KNAU). He also teaches anatomy and biomechanics at KNAU. In addition, he has worked as illustrator for numerous publications in the field of medicobiology.

Ronald Klomp

For many years Klomp has supervised top middle-distance runners such as Ellen van Langen, Simon Vroemen, Jim Svenøy, Marcel Laros and Gert-Jan Liefers. In his classes at KNAU, he has taught hundreds of individuals how to train running. Together with Frans Bosch he has written the standard work about running titled Running. He is presently using his abundant practical experience and background as academic in the field of movement to teach medicobiology classes at the Fontys Sporthogeschool.

Further Reading:
R. McN. Alexander (1992) The Human Machine. Natural History Museum Publications and Columbia University Press.
R. McN. Alexander (2002) Energetics and optimization of human walking and running. American Journal of Human Biology 14: 641-648.
R. McN. Alexander (2003) Principles of Animal Locomotion. Princeton University Press. (For scientists with some competence in mathematics.)
F. Bosch & R. Klomp (2005) Running. Elsevier.
R. Margaria (1976) Biomechanics and Energetics of Muscular Exercise. Clarendon Press. (A classic by a pioneer in the subject.)

Copyrights A-Film Distribution B.V. 2005

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