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The Art of Running:
A Biomechanical Look at Efficiency

by Dan Hughes

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The image of a distance runner running along may cause one to conjure thoughts of efficiency, and virtual ease of movement. The fact is that there are many distance runners who make running appear very easy for them. There are other runners who look as if they have to work quite a bit harder to maintain pace. In this case looks are not deceiving, through qualitative analysis an individual can determine the inefficiencies in a runner's technique. These inefficiencies could prove to be costly, and limit the performance of the athlete. Unlike other sports distance runners rarely analyze and try to improve their mechanics. It is perceivable that a 1 % decrease in the energy cost of running could improve a marathoners time by nearly two minutes (Costill, 1986). These energy costs due to biomechanical inefficiencies may cause an individual to work at a higher level of their maximal oxygen uptake capacity. This study will look at the basic biomechanics of running with relation to running economy and  VO2 max.

     Running is a structured movement pattern or a motor skill. A motor skill can be defined as a group of simple, natural movements combined toward achieving a goal (Henatsch & Langer, 1985). Training and technique are very important in developing or improving a sport skill. Generally as the adaptation to training takes place, the efficiency of the skill improves. This can be seen in an improved running style. There are four characteristics that can be observed as a skilled performer optimizes energy expenditure to achieve a high level of performance (Martin & Coe, 1991). First there is improved balance and coordination, therefore reducing postural work. Then unnecessary and exuberant movements are eliminated. Thirdly necessary movements are refined to ensure that these occur in proper direction, with optimum quickness to minimize the loss of kinetic energy. Next the most important muscles for movement, prime movers, are used effectively. This includes the coordination of agonists, antagonist, and synergist. This will result in minimum energy used to initiate the movement, and minimal opposing resistance. These factors can be observed as a novice runner becomes more efficient through adaptation in the training process. There are several biomechanical principles that can be related to running (Martin & Coe, 1991).

    The first principle is that force must be applied to change the velocity of an object in motion. An example of this concept would be a runner who looses velocity during the airborne phase of each stride, and to maintain continual motion, force must be applied by the support leg at takeoff. The next principle is that linear and angular motion need integration to permit optimum performance of movement patterns. This can be seen with the flexion and extension of the lower limbs, and how these movements work with the rotation, abduction, adduction of the hips and spine. All these movements about various planes must be complementary. The third principle is the longer the length of a lever, the greater the potential linear velocity at its end. This principle is reversed in running, where the limbs are shortened to bring them forward with less energy requirement. The fourth principle is for every action there is a reaction equal in amount but opposite in direction. This can be observed with every foot-strike, the landing surface pushes back with a force equal to the impact force, driving the runner upward and forward in a direction opposite to that of impact. The running and walking gait cycles are similar to each other.

     Running and walking are both fundamental skills, but differ from many other skills because they are continuous. One foot moves in front of the other, with the arms moving in the opposite direction synchronously. The trunk should have minimal forward lean to reduce the stress placed on the postural muscles. The trunk and head make up 60% of body weight, and should be kept directly over the point of ground support. The feature that most distinguishes running from walking is that in running there is a period where the runner is airborne.

      There are various phases during the running cycle that can be broken into two phases: support and forward recovery (Slocum & James, 1968). During running the support phase can be reduced to as little as 30% of the total cycle time. On the average the support phase occupies 40% of the running cycle, and the free-floating forward recovery phase occupies about 60%. The support phase consists of the periods: foot-strike, mid-support, and takeoff. During forward recovery there are three periods: follow-through, forward swing, and foot descent. The follow-through, and foot descent are known as the float period.

     The foot-strike is the start of the running cycle. As the foot touches the ground it will be slightly ahead of the center of mass. This will minimize the braking effect, and help to carry linear momentum forward. When the foot contact occurs, several actions take place: the knee flexes, the tibia internally rotates, the ankle plantar flexes, and the subtalar joint pronates (Miliron & Cavanagh, 1990). The pronation helps to absorb some of the compressive shock forces, torque conversion, adjustment to uneven ground contours, and maintenance of balance. It is necessary to have a certain amount of pronation to disseminate the energy of the foot-strike. If there is too little or too much pronation injuries may occur (Edington, Frederick & Cavanagh, 1990). There are corrective footwear, and orthotics available to correct these biomechanical problems (Edington et al.). The foot during the  foot-strike should be straight and in line with the direction of linear motion. If the feet are turned outward it reduces the distance covered, and puts more stress on the knees and lower extremities (Williams, 1990). The next period in the running cycle is the mid-support.

     The period of mid-support sees the foot transform from a mobile structure into a rigid lever that can support several times the body weight of the runner. This change is due to the position of the subtalor and midtarsal joints of the foot. Much of the rigidity of the foot can be attributed to the shape of the bones, and the tension on the ligaments. The supination of the subtalor joint forms a rigid lever for forward propulsion. This occurs through a series of events including the knee joint extending, the lower extremity rotates externally, the calcaneus inverts, the midtarsal joint locks, and the foot becomes a rigid lever. This allows for the propulsive force to be thrust backward and downward from a combination of hip extension, knee extension, and ankle plantar flexion. The mid-support period ends with the heel rising upward into takeoff.

     When the foot leaves the ground, the follow-through period begins. This is the initial floating period of the forward recovery phase. The next period of the forward recovery phase is the forward swing. This is achieved through hip flexion and forward rotation of the pelvis, which cause the thigh to start moving forward. Hip flexion is assisted by flexion of the knee; this shortens the lever allowing for greater forward velocity. After maximum hip flexion is reached, the final float period called foot descent begins. Knee extension occurs to promote movement of the lower limb. The hamstrings slow the forward movement of the foot and leg by generating tension. As the next foot strike occurs, ideally the foot will be moving backward with a velocity equal to the forward movement of the trunk. Stride length and the stride rate can play a critical role in the efficiency of a runner.

     It has been well documented that humans increase both stride length and stride frequency as running velocity increases(Cavanagh & Kram, 1990). Stride length tends to reach its maximum at higher velocities of running(Cavanagh & Kram). Stride frequency tends to increase more at the higher velocities. The exact combination of length and frequency at a particular velocity may differ due to such variables as leg length, hip flexion, breathing rate, and state of fatigue (Cavanagh & Kram). The optimum stride length for most runners occurs subconsciously, and is developed with practice over time. A change in the optimum stride either  by lengthening or shortening can cause energy costs to rise (Cavanaugh & Williams, 1979). Over-striding can be energy costly due to the foot-strike deceleration it causes. Along with the stride variables, the upper extremities also play a key role in the running process.

     The arm action in running is compensatory and synchronous with the action of the legs (Hinrichs, 1990). The arms help the legs in propelling the body upward, thus providing lift to the runner. The arms also aid in achieving a constant horizontal velocity, which could lead to a reduction in energy cost (Hinrichs). Williams (1980) reported that runners who were more economical in terms of oxygen consumption tended to use less vigorous arm swing. Theoretically arm swing should increase with running velocity. Also as a runner begins to fatigue the use of arm swing becomes more important, and helps the runner to maintain lift and drive.  The arms should be carried low and relaxed, with the hands cupped loosely. This will help the runner from tightening up in the upper body. In an ideal situation the elbows should swing forward and backward in a straight line (“Up in Arms,” 1980). Lateral motion or outward rotation can also hinder efficiency. The angle of arm flexion should be around 90 degrees. This should not be a fixed angle, but should allow for some movement on either side of it. This will help to smooth out the form and avoid robot arm action. The arms due play vital role in running and are not just merely used for balance. Aristotle once said, “runners run faster if they swing their arms.” All the different variables in running produce the running economy of an athlete, which have an impact on the metabolic energy costs.

     It is reasonable to expect mechanics of movement do have an influence on the metabolic costs of running. There are several studies that suggest  a strong relationship between maximal oxygen consumption and running performance, there are also indicators that running economy can be an important factor (Daniels, 1985). It is then logical to assume that an improvement in an individuals running mechanics would result in less energy costs, and would allow for better performances (Williams, 1990). An example would be two runners with similar VO2 max ratings, and compete against each other on a regular basis at the marathon distance. One of the runners has better mechanics and continually finishes several minutes ahead of the other  runner. The more efficient runner is able to run at a faster pace with a lower percentage of their VO2 max being utilized. It cost some runners more to run at a given speed than it does others with better technique (Costill, 1986). This knowledge would be beneficial for coaches and athletes to understand the basic concepts of running biomechanics, and how to improve efficiency, which would ameliorate performance.                  


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     Cavanagh, P., & Kram, R. (1990). Stride Length in Distance Running: Velocity, body dimensions, and added mass effects. In P.R. Cavanagh (Ed.), Biomechanics of Distance Running (pp. 35-63). Champaign, IL: Human Kinetics.

     Cavanagh, P, & Williams, K. (1979). Should You Change Your Stride Length?. Runners World, 14 (7), 64.

     Costill, D. (1986). Inside Running: Basics of sports physiology. Muncie, IN: Brown & Benchmark.

     Edington, C., Frederick, E.C., & Cavanagh, P. (1990). Rearfoot Motion in Distance Running. In P.R. Cavanagh (Ed.), Biomechanics of Distance Running (135-161). Champaign, IL: Human Kinetics.

     Henatsch, H.D., & Langer, H.H. (1985). Basic neurophysiology of motor skills in sport: A review. International Journal of Sports Medicine, 6, 2-14.

     Hinrichs, R. (1990). Upper Extremity Function in Distance Running. In P.R. Cavanagh (Ed), Biomechanics of Distance Running (107-131). Champaign, IL: Human Kinetics.

     Martin, D., & Coe, P. (1991). Training Distance Runners. Champaign, IL: Human Kinetics.

     Milliron, M, & Cavanagh, P. (1990). Sagittal Plane Kinematics of the Lower Extremity During Distance Running. In P.R. Cavanagh (Ed.). Biomechanics of Distance Running (65-97). Champaign, IL: Human Kinetics.

     Slocum, D.B., & James, S.L. (1968). Biomechanics of running. Journal of the American Medical Association, 205, 721-728.

     Up in Arms. (1980, April). Runners World, 53-57.

     Williams, K. (1990). Relationships Between  Distance Running Biomechanics and Running Economy. In P.R. Cavanagh (Ed.). Biomechanics of Distance Running (271-299). Champaign, IL: Human Kinetics.  



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