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A split leap executed by an acro dancer. This is one of several types of leaps found in dance.

Jumping or leaping is a form of locomotion or movement in which an organism or non-living (e.g., robotic) mechanical system propels itself through the air along a ballistic trajectory. Jumping can be distinguished from running, galloping and other gaits in which the entire body is temporarily airborne by the relatively long duration of the aerial phase and high angle of initial launch.

Some animals, such as the kangaroo, employ jumping (commonly called hopping in this instance) as their primary form of locomotion, while others, such as frogs, use it only as a means to escape predators. Jumping is also a key feature of various activities and sports, including the long jump, high jump, and show jumping.

Contents

Physics of jumping

All jumping involves the application of force against a substrate, which in turn generates a reactive force that propels the jumper away from the substrate. Any solid or liquid capable of producing an opposing force can serve as a substrate, including ground or water. Examples of the latter include dolphins performing traveling jumps, and Indian skitter frogs executing standing jumps from water.

Jumping organisms are rarely subject to significant aerodynamic forces and, as a result, their jumps are governed by the basic physical laws of ballistic trajectories. Consequently, while a bird may jump into the air in order to initiate flight, no movement it performs once airborne can be considered jumping as its flight path is no longer dictated by the initial jump conditions. Similarly, it is impossible to jump underwater as hydrodynamic forces would greatly exceed gravitational forces.

Following the moment of launch (i.e., initial loss of contact with the substrate), a jumper will traverse a parabolic path. The launch angle and initial launch velocity determine the travel distance, duration, and height of the jump. The maximum possible horizontal travel distance occurs at a launch angle of 45 degrees, but any launch angle between 35 and 55 degrees will result in ninety percent of the maximum possible distance.

Muscles (or other actuators in non-living systems) do physical work, adding kinetic energy to the jumper's body over the course of a jump's propulsive phase. This results in a kinetic energy at launch that is proportional to the square of the jumper's velocity. The more work the muscles do, the greater the launch velocity and thus the greater the acceleration and the shorter the time interval of the jump's propulsive phase.

Mechanical power (work per unit time) and the distance over which that power is applied (e.g., leg length) are the key determinants of jump distance and height. As a result, many jumping animals have long legs and muscles that are optimized for maximal power according to the force-velocity relationship of muscles. The maximum power output of muscles is limited, however. To circumvent this limitation, many jumping species will slowly pre-stretch elastic elements such as tendons or apodemes in order to store work as strain energy; this energy can be released at a much higher rate (higher power) than muscle, thus increasing launch energy to levels beyond what muscle alone is capable of.

A jumper may be either stationary or moving when initiating a jump. In a jump from stationary (i.e., a standing jump), all of the work required to accelerate the body through launch is done in a single movement. In a moving jump or running jump, the jumper introduces additional vertical velocity at launch while conserving as much horizontal momentum as possible. Unlike stationary jumps, in which the jumper's kinetic energy at launch is solely due to the jump movement, moving jumps have a higher energy that results from the inclusion of the horizontal velocity preceding the jump. Consequently, jumpers are able to jump greater distances when starting from a run.

Anatomy

A bullfrog skeleton, showing elongate limb bones and extra joints. Red marks indicate bones which have been substantially elongated in frogs and joints which have become mobile. Blue indicates joints and bones which have not been modified or only somewhat elongated.

Animals use a wide variety of anatomical adaptations for jumping. These adaptations are exclusively concerned with the launch, as any post-launch method of extending range or controlling the jump must use aerodynamic forces, and thus is considered gliding or parachuting.

Aquatic species rarely display any particular specializations for jumping. Those which are good jumpers usually are primarily adapted for speed, and execute moving jumps by simply swimming to the surface at a high velocity. A few primarily aquatic species which can jump while on land, such as mud skippers, do so via a flick of the tail

Limb morphology

In terrestrial animals, the primary propulsive structure is the legs, though a few species use their tails. Typical characteristics of jumping species include long legs, large leg muscles, and additional limb elements.

Long legs increase the time and distance over which a jumping animal can push against the substrate, thus allowing more power and faster, farther jumps. Large leg muscles can generate greater force, resulting in improved jumping performance. In addition to elongated leg elements, many jumping animals have modified foot and ankle bones that are elongated and possess additional joints, effectively adding more segments to the limb and even more length.

Frogs are an excellent example of all three trends: frog legs can be nearly twice the body length, leg muscles may account for up to twenty percent of body weight, and they have not only lengthened the foot, shin and thigh, but extended the ankle bones into another limb joint and similarly extended the hip bones and gained mobility at the sacrum for a second 'extra joint'. As a result, frogs are the undisputed champion jumpers of vertebrates, leaping over fifty body lengths, a distance of more than eight feet.[1]

Power amplification through stored energy

Grasshoppers are known to use elastic energy storage in order to increase jumping distance. As noted above, power output is a principal determinant of jump distance, but physiological constraints limit muscle power to approximately 375 Watts per kilogram of muscle.[2] To overcome this limitation, grasshoppers anchor their legs via an internal "catch mechanism" while their muscles stretch an elastic apodeme (similar to a vertebrate tendon). When the catch is released, the apodeme rapidly releases its energy. Because the apodeme releases energy more quickly than muscle, its power output exceeds that of the muscle that produced the energy.

This is analogous to a human throwing an arrow by hand versus using a bow; the use of elastic storage (the bow) allows the muscles to operate closer to isometric on the force-velocity curve. This enables the muscles to do work over a longer time and thus produce more energy than they otherwise could, while the elastic element releases that work faster than the muscles can. The use of elastic energy storage has been found in jumping mammals as well as in frogs, with commensurate increases in power ranging from two to seven times that of equivalent muscle mass.[3]

Classification

One way to classify jumping is by the manner of foot transfer.[4] In this classification system, five basic jump forms are distinguished:

  • Jump - jumping from and landing on two feet
  • Hop - jumping from one foot and landing on the same foot
  • Leap - jumping from one foot and landing on the other foot
  • Assemble - jumping from one foot and landing on two feet
  • Sissonne - jumping from two feet and landing on one foot

Leaping gaits, which are distinct from running gaits (see Locomotion), include cantering, galloping, and pronging.[5]

Devices and techniques for enhancing jumping height

The height of a jump may be increased by using a trampoline or by converting horizontal velocity into vertical velocity with the aid of a device such as a half pipe.

Various exercises can be used to increase an athlete's vertical jumping height. One category of such exercises—plyometrics—employs repetition of discrete jumping-related movements to increase speed, agility, and power.

References

  1. ^ Zug, G. R. (1978). Anuran Locomotion: Structure and Function. II. Jumping performance of semiacquatic, terrestrial, and arboreal frogs. Smithsonian Contributions to Zoology 276, iii-31.  
  2. ^ Marsh, R. L. (1994). Jumping ability of anuran amphibians. Advances in Veterinary Science and Comparative Medicine 38, 51-111.  
  3. ^ Peplowski, M. M. and Marsh, R. L. (1997). Work and power output in the hindlimb muscles of cuban tree frogs Osteopilus septentrionalis during jumping. J. Exp. Biol. 200, 2861-2870.  
  4. ^ Study Guide for Elementary Labanotation by Peggy Hackney, Sarah Manno (Editor), Muriel Topaz (Editor)
  5. ^ Tristan David Martin Roberts (1995) Understanding Balance: The Mechanics of Posture and Locomotion, Nelson Thornes, ISBN 0412601605.

See also


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

JUMPING,' a branch of athletics which has been cultivated from the earliest times (see Athletic Sports). Leaping competitions formed a part of the pentathlon, or quintuple games, of the Olympian festivals, and Greek chronicles record that the athlete Phayllus jumped a distance of 55 Olympian, or more than 30 English, feet. Such a leap could not have been made without weights carried in the hands and thrown backwards at the moment of springing. These were in fact employed by Greek jumpers and were called halteres. They were masses of stone or metal, nearly semicircular, according to Pausanias, and the fingers grasped them like the handles of a shield. Halteres were also used for general exercise, like modern dumb-bells. The Olympian jumping took place to the music of lutes.

Jumping has always been popular with British athletes, and tradition has handed down the record of certain leaps that border on the incredible. Two forms of jumping are included in modern athletic contests, the running long jump and the running high jump; but the same jumps, made from a standing position, are also common forms of competition, as well as the hop step and jump, two hops and jump, two jumps, three jumps, five jumps and ten jumps, either with a run or from a standing position. These events are again divided into two categories by the use of weights, which are not allowed in championship contests.

I The verb " to jump " only dates from the beginning of the 16th century. The New English Dictionary takes it to be of onomatopoeic origin and does not consider a connexion with Dan. gumpe, Icel. goppa, &c., possible. The earlier English word is " leap " (O.E. hleapan, to run, jump, cf. Ger. laufen). xv. 18 a In the running long jump anything over 18 ft. was once considered good, while Peter O'Connor's world's record (r 90 I) is 24 ft. r r 4 in. The jump is made, after a short fast run on a cinder path, from a joist sunk into the ground flush with the path, the jumper landing in a pit filled with loose earth, its level a few inches below that of the path. The joist, called the " take-off," is painted white, and all jumps are measured from its edge to the nearest mark made by any part of the jumper's person in landing.

In the standing long jump, well spiked shoes should be worn, for it is in reality nothing but a push against the ground, and a perfect purchase is of the greatest importance. Weights held in the hands of course greatly aid the jumper. Without weights J. Darby (professional) jumped 12 ft. 11 in. and R. C. Ewry (American amateur) II ft. 4s in. With weights J. Darby covered 14 ft. 9 in. at Liverpool in 1890, while the amateur record is 12 ft. 91 in., made by J. Chandler and G. L. Hellwig (U.S.A.). The standing two, three, five and ten jumps are merely repetitions of the single jump, care being taken to land with the proper balance to begin the next leap. The record for two jumps without weights is 22 ft. 22 in., made by H. M. Johnson (U.S.A.); for three jumps without weights, R. C. Ewry, 35 ft. 74 in.; with weights J. Darby, 41 ft. 7 in.

The hop step and jump is popular in Ireland and of ten included in the programmes of minor meetings, and so is the two hops and a jump. The record for the first, made by W. McManus, is 49 ft. 21 in. with a run and without weights; for the latter, also with a run and without weights, 49 ft. z in., made by J. B. Conolly.

In the running high jump also the standard has improved. In 1864 a jump of 5 ft. 6 in. was considered excellent. The Scotch professional Donald Dinnie, on hearing that M. J. Brooks of Oxford had jumped 6 ft. 22 in. in 1876, wrote to the newspapers to show that upon a priori grounds such an achievement was impossible. Since then many jumpers who can clear over 6 ft. have appeared. In 1895 M. F. Sweeney of New York accomplished a jump of 6 ft. 5t in. Ireland has produced many firstclass high jumpers, nearly all tall men, P. Leahy winning the British amateur record in Dublin in 1898 with a jump of 6 ft. 44 in. The American A. Bird Page, however, although only 5 ft. 61 in. in height, jumped 6 ft. 4 in. High jumping is done over a light staff or lath resting upon pins fixed in two uprights upon which a scale is marked. The " take-off," or ground immediately in front of the uprights from which the spring is made, is usually grass in Great Britain and cinders in America. Some jumpers run straight at the bar and clear it with body facing forward, the knees being drawn up almost to the chin as the body clears the bar; others run and spring sideways, the feet being thrown upwards and over the bar first, to act as a kind of lever in getting the body over. There should be a shallow pit of loose earth or a mattress to break the fall.

The standing high jump is rarely seen in regular athletic meetings. The jumper stands sideways to the bar with his arms extended upwards. He then swings his arms down slowly, bending his knees at the same time, and, giving his arms a violent upward swing, springs from the ground. As the body rises the arms are brought down, one leg is thrown over the bar, and the other pulled, almost jerked, after it. The record for the standing high jump without weights is 6 ft., by J. Darby in 1892.

By the use of a spring-board many extraordinary jumps have been made, but this kind of leaping is done only by circus gymnasts and is not recognized by athletic authorities. For pole-jumping See Pole-Vaulting.


" See Encyclopaedia of Sport; M. W. Ford, "Running High Jump," Outing, vol. xviii.; " Running Broad Jump," Outing, vol. xix.; " Standing Jumping," Outing, vol. xix.; " Miscellaneous Jumping," Outing, vol. xx. Also Sporting and Athletic Register (annual).


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Simple English

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Jumping exercise, Hollywood.
Jumping is a form of movement in which an organism propels itself through the air along a ballistic trajectory. Jumping can be distinguished from running, galloping and other gaits in which the entire body is temporarily airborne by the relatively long duration.

Some animals, such as the kangaroo, employ jumping as their primary form of locomotion, while others, such as frogs, use it only as a means to escape predators. Jumping is also a key feature of various activities and sports, including the long jump, high jump, and show jumping.

Classification

One way to classify jumping is by the manner of foot transfer.[1] In this classification system, five basic jumping forms are distinguished:

  • Jump - jumping from and landing on two feet
  • Hop - jumping from one foot and landing on the same foot
  • Leap - jumping from one foot and landing on the other foot
  • Assemble - jumping from one foot and landing on two feet
  • Sissonne - jumping from two feet and landing on one foot
  • Bound - a leap onward or upward
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Notes

  1. Study Guide for Elementary Labanotation by Peggy Hackney, Sarah Manno (Editor), Muriel Topaz (Editor)







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