1.
Acro dance
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Acro dance is a style of dance that combines classical dance technique with precision acrobatic elements. It is defined by its character, its unique choreography, which seamlessly blends dance and acrobatics. It is a dance style in amateur competitive dance as well as in professional dance theater. Acro dance is known by other names including acrobatic dance and gymnastic dance, though it is most commonly referred to simply as acro by dancers. Acro is a challenging dance style for dancers as it requires them to be trained in both dance and acrobatic skills. Acro dancers must be in excellent physical condition as well, because acro is a demanding activity. Acrobatic dance emerged in the United States and Canada in the early 1900s, acrobatic dance did not suddenly appear in vaudeville, rather, it appeared gradually over time in a variety of forms, and consequently no individual performer has been cited as its originator. Sherman Coates, who performed with the Watermelon Trust from 1900 to 1914, was recalled by fellow dancers as the first acrobatic dancer they had ever seen. In 1914, acrobat Lulu Coates formed the Crackerjacks, a vaudeville troupe that included acrobatic dance in their performance repertoire up until the group disbanded in 1952. Many other popular vaudeville companies combined acrobatics and dance in their shows, since the decline of the vaudeville era, acrobatic dance has undergone a multi-faceted evolution to arrive at its present-day form. Also, vaudeville acrobatic dances were often more than acrobatics set to music, whereas modern acro dance is fundamentally dance. A defining characteristic of acro is the smooth, graceful transitions between dance and acrobatic movements, also, a dance must have a significant percentage of dance movement, with respect to its acrobatic content, in order for it to be categorized as acro. The dance movements in acro are founded in ballet, jazz, lyrical, Acro dance movements are not restricted to these dance styles, but the complete absence of these styles will typically cause a dance to be categorized as something other than acro. The acrobatic movements and acts of balance performed in a dance are referred to as tricks. A variety of tricks are performed in acro dance, varying widely in complexity. Aside from the requirement that dancers possess the requisite skills to perform tricks. Solo tricks can be performed by independent dancers in solo or group dances, examples of this are, Double tricks—also known as partnering tricks—can only be performed by a pair of dancers. An example of this is the tuck, in which one dancer forms a saddle with his hands
2.
Dance
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Dance is a performance art form consisting of purposefully selected sequences of human movement. This movement has aesthetic and symbolic value, and is acknowledged as dance by performers and observers within a particular culture, Dance can be categorized and described by its choreography, by its repertoire of movements, or by its historical period or place of origin. Other forms of movement are sometimes said to have a dance-like quality, including martial arts, gymnastics, figure skating, synchronized swimming. Theatrical dance, also called performance or concert dance, is intended primarily as a spectacle and it often tells a story, perhaps using mime, costume and scenery, or else it may simply interpret the musical accompaniment, which is often specially composed. Examples are western ballet and modern dance, Classical Indian dance and Chinese and Japanese song, most classical forms are centred upon dance alone, but performance dance may also appear in opera and other forms of musical theatre. Such dance seldom has any narrative, a group dance and a corps de ballet, a social partner dance and a pas de deux, differ profoundly. Even a solo dance may be solely for the satisfaction of the dancer. On the other hand, some cultures lay down strict rules as to the dances in which, for example. Archeological evidence for early dance includes 9, 000-year-old paintings in India at the Rock Shelters of Bhimbetka and it has been proposed that before the invention of written languages, dance was an important part of the oral and performance methods of passing stories down from generation to generation. The use of dance in trance states and healing rituals is thought to have been another early factor in the social development of dance. References to dance can be found in very early recorded history, Greek dance is referred to by Plato, Aristotle, Plutarch, the Bible and Talmud refer to many events related to dance, and contain over 30 different dance terms. In Chinese pottery as early as the Neolithic period, groups of people are depicted dancing in a line holding hands, Dance is further described in the Lüshi Chunqiu. Primitive dance in ancient China was associated with sorcery and shamanic rituals, during the first millennium BCE in India, many texts were composed which attempted to codify aspects of daily life. Bharata Munis Natyashastra is one of the earlier texts and it mainly deals with drama, in which dance plays an important part in Indian culture. It categorizes dance into four types - secular, ritual, abstract, the text elaborates various hand-gestures and classifies movements of the various limbs, steps and so on. A strong continuous tradition of dance has since continued in India, through to modern times, where it continues to play a role in culture, ritual, and, notably, the Bollywood entertainment industry. Many other contemporary dance forms can likewise be traced back to historical, traditional, ceremonial, Dance is generally, though not exclusively, performed with the accompaniment of music and may or may not be performed in time to such music. Some dance may provide its own audible accompaniment in place of music, many early forms of music and dance were created for each other and are frequently performed together
3.
Robotics
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Robotics is the interdisciplinary branch of engineering and science that includes mechanical engineering, electrical engineering, computer science, and others. Robotics deals with the design, construction, operation, and use of robots, as well as systems for their control, sensory feedback. These technologies are used to develop machines that can substitute for humans, Robots can be used in any situation and for any purpose, but today many are used in dangerous environments, manufacturing processes, or where humans cannot survive. Robots can take on any form but some are made to resemble humans in appearance and this is said to help in the acceptance of a robot in certain replicative behaviors usually performed by people. Such robots attempt to replicate walking, lifting, speech, cognition, many of todays robots are inspired by nature, contributing to the field of bio-inspired robotics. Throughout history, it has been assumed that robots will one day be able to mimic human behavior. Many robots are built to do jobs that are hazardous to people such as defusing bombs, finding survivors in unstable ruins, Robotics is also used in STEM as a teaching aid. The word robotics was derived from the robot, which was introduced to the public by Czech writer Karel Čapek in his play R. U. R. which was published in 1920. The word robot comes from the Slavic word robota, which means labour, the play begins in a factory that makes artificial people called robots, creatures who can be mistaken for humans – very similar to the modern ideas of androids. Karel Čapek himself did not coin the word and he wrote a short letter in reference to an etymology in the Oxford English Dictionary in which he named his brother Josef Čapek as its actual originator. According to the Oxford English Dictionary, the word robotics was first used in print by Isaac Asimov, published in May 1941 in Astounding Science Fiction. Asimov was unaware that he was coining the term, since the science and technology of electrical devices is electronics, he assumed robotics already referred to the science and technology of robots. In some of Asimovs other works, he states that the first use of the word robotics was in his short story Runaround, however, the original publication of Liar. Predates that of Runaround by ten months, so the former is generally cited as the words origin, in 1942, the science fiction writer Isaac Asimov created his Three Laws of Robotics. In 1948, Norbert Wiener formulated the principles of cybernetics, the basis of practical robotics, fully autonomous only appeared in the second half of the 20th century. The first digitally operated and programmable robot, the Unimate, was installed in 1961 to lift hot pieces of metal from a die casting machine, commercial and industrial robots are widespread today and used to perform jobs more cheaply, more accurately and more reliably, than humans. They are also employed in jobs which are too dirty, dangerous. For example, a designed to travel across heavy dirt or mud
4.
Kangaroo
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The kangaroo is a marsupial from the family Macropodidae. The Australian government estimates that 34.3 million kangaroos lived within the commercial harvest areas of Australia in 2011, as with the terms wallaroo and wallaby, kangaroo refers to a polyphyletic grouping of species. All three refer to members of the taxonomic family, Macropodidae, and are distinguished according to size. The largest species in the family are called kangaroos and the smallest are generally called wallabies, the term wallaroos refers to species of an intermediate size. There is also the tree-kangaroo, another genus of macropod, which inhabits the rainforests of New Guinea, far northeastern Queensland. Kangaroos have large, powerful legs, large feet adapted for leaping, a long muscular tail for balance. Like most marsupials, female kangaroos have a pouch called a marsupium in which joeys complete postnatal development, the large kangaroos have adapted much better than the smaller macropods to land clearing for pastoral agriculture and habitat changes brought to the Australian landscape by humans. Many of the species are rare and endangered, while kangaroos are relatively plentiful. The kangaroo is important to both Australian culture and the image, and consequently there are numerous popular culture references. Wild kangaroos are shot for meat, leather hides, and to grazing land. Although controversial, kangaroo meat has perceived health benefits for human consumption compared with traditional meats due to the low level of fat on kangaroos, the word kangaroo derives from the Guugu Yimithirr word gangurru, referring to grey kangaroos. Cook first referred to kangaroos in his entry of 4 August. Guugu Yimithirr is the language of the people of the area, a common myth about the kangaroos English name is that kangaroo was a Guugu Yimithirr phrase for I dont understand you. According to this legend, Cook and Banks were exploring the area when they happened upon the animal and they asked a nearby local what the creatures were called. The local responded Kangaroo, meaning I dont understand you, which Cook took to be the name of the creature and this myth was debunked in the 1970s by linguist John B. Haviland in his research with the Guugu Yimithirr people, Kangaroos are often colloquially referred to as roos. Male kangaroos are called bucks, boomers, jacks, or old men, females are does, flyers, or jills, the collective noun for kangaroos is a mob, troop, or court. There are four species that are referred to as kangaroos
5.
Animal locomotion
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Animal locomotion, in ethology, is any of a variety of movements or methods that animals use to move from one place to another. Some modes of locomotion are self-propelled, e. g. running, swimming, jumping, flying, hopping, soaring and gliding. There are also many species that depend on their environment for transportation. Animals move for a variety of reasons, such as to food, a mate. For many animals, the ability to move is essential for survival and, as a result, natural selection has shaped the locomotion methods, the term locomotion is formed in English from Latin loco from a place + motio motion, a moving. Animals move through, or on, four types of environment, aquatic, terrestrial, fossorial, many animals—for example semi-aquatic animals, and diving birds—regularly move through more than one type of medium. In some cases, the surface they move on facilitates their method of locomotion, in water, staying afloat is possible using buoyancy. If an animals body is less dense water, it can stay afloat. This requires little energy to maintain a position, but requires more energy for locomotion in the horizontal plane compared to less buoyant animals. The drag encountered in water is greater than in air. Morphology is therefore important for efficient locomotion, which is in most cases essential for basic functions such as catching prey, a fusiform, torpedo-like body form is seen in many aquatic animals, though the mechanisms they use for locomotion are diverse. The primary means by which fish generate thrust is by oscillating the body from side-to-side, finer control, such as for slow movements, is often achieved with thrust from pectoral fins. Some fish, e. g. the spotted ratfish and batiform fish use their fins as the primary means of locomotion. Marine mammals oscillate their body in an up-and-down direction, other animals, e. g. penguins, diving ducks, move underwater in a manner which has been termed aquatic flying. Some fish propel themselves without a motion of the body, as in the slow-moving seahorses. Other animals, such as cephalopods, use jet propulsion to travel fast, other swimming animals may rely predominantly on their limbs, much as humans do when swimming. Dolphins sometimes ride on the bow waves created by boats or surf on breaking waves. Benthic locomotion is movement by animals that live on, in, in the sea, many animals walk over the seabed
6.
Frog
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A frog is any member of a diverse and largely carnivorous group of short-bodied, tailless amphibians composing the order Anura. The oldest fossil proto-frog appeared in the early Triassic of Madagascar, Frogs are widely distributed, ranging from the tropics to subarctic regions, but the greatest concentration of species diversity is in tropical rainforests. There are approximately 4,800 recorded species, accounting for over 85% of extant amphibian species and they are also one of the five most diverse vertebrate orders. The body plan of a frog is generally characterized by a stout body, protruding eyes, cleft tongue, limbs folded underneath. Besides living in water and on dry land, the adults of some species are adapted for living underground or in trees. The skin of the frog is glandular, with secretions ranging from distasteful to toxic, Frogs skins vary in colour from well-camouflaged dappled brown, grey and green to vivid patterns of bright red or yellow and black to advertise toxicity and warn off predators. Frogs typically lay their eggs in water, the eggs hatch into aquatic larvae called tadpoles that have tails and internal gills. They have highly specialized rasping mouth parts suitable for herbivorous, omnivorous or planktivorous diets, the life cycle is completed when they metamorphose into adults. A few species deposit eggs on land or bypass the tadpole stage, adult frogs generally have a carnivorous diet consisting of small invertebrates, but omnivorous species exist and a few feed on fruit. Frogs are extremely efficient at converting what they eat into body mass and they are an important food source for predators and part of the food web dynamics of many of the worlds ecosystems. The skin is semi-permeable, making them susceptible to dehydration, so they live in moist places or have special adaptations to deal with dry habitats. Frogs are valued as food by humans and also have many roles in literature, symbolism. Frog populations have declined significantly since the 1950s, more than one third of species are considered to be threatened with extinction and over one hundred and twenty are believed to have become extinct since the 1980s. The number of malformations among frogs is on the rise and a fungal disease. Conservation biologists are working to understand the causes of these problems, the name frog derives from Old English frogga, abbreviated to frox, forsc, and frosc, probably deriving from Proto-Indo-European preu = to jump. About 88% of amphibian species are classified in the order Anura and these include around 4,810 species in 33 families, of which the Leptodactylidae, Hylidae and Ranidae are the richest in species. The use of the common frog and toad has no taxonomic justification. From a classification perspective, all members of the order Anura are frogs, there are numerous exceptions to this rule
7.
Long jump
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The long jump is a track and field event in which athletes combine speed, strength and agility in an attempt to leap as far as possible from a take off point. Along with the jump, the two events that measure jumping for distance as a group are referred to as the horizontal jumps. This event has a history in the Ancient Olympic Games and has been a modern Olympic event for men since the first Olympics in 1896 and for women since 1948. If the competitor starts the leap with any part of the foot past the foul line, a layer of plasticine is placed immediately after the board to detect this occurrence. An official will also watch the jump and make the determination, therefore, it is in the best interest of the competitor to get as close to the foul line as possible. Competitors are allowed to place two marks along the side of the runway in order to assist them to jump accurately. At a lesser meet and facilities, the plasticine will likely not exist, at a smaller meet, the number of attempts might also be limited to four or three. Each competitor has a set number of attempts and that would normally be three trials, with three additional jumps being awarded to the best 8 or 9 competitors. All legal marks will be recorded but only the longest legal jump counts towards the results, the competitor with the longest legal jump at the end of competition is declared the winner. In the event of a tie, then comparing the next best jumps of the tied competitors will be used to determine place. In a large, multi-day elite competition, a set number of competitors will advance to the final round, a set of 3 trial round jumps will be held in order to select those finalists. For record purposes, the maximum accepted wind assistance is two metres per second, the long jump is the only known jumping event of Ancient Greeces original Olympics pentathlon events. All events that occurred at the Olympic Games were initially supposed to act as a form of training for warfare, the long jump emerged probably because it mirrored the crossing of obstacles such as streams and ravines. After investigating the surviving depictions of the ancient event it is believed that unlike the modern event, the athletes carried a weight in each hand, which were called halteres. These weights were swung forward as the athlete jumped in order to increase momentum and it is commonly believed that the jumper would throw the weights behind him in midair to increase his forward momentum, however, halteres were held throughout the duration of the jump. Swinging them down and back at the end of the jump would change the center of gravity and allow the athlete to stretch his legs outward. The jump itself was made from the bater and it was most likely a simple board placed on the stadium track which was removed after the event. The jumpers would land in what was called a skamma, the idea that this was a pit full of sand is wrong
8.
High jump
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The high jump is a track and field event in which competitors must jump unaided over a horizontal bar placed at measured heights without dislodging it. In its modern most practised format, a bar is placed between two standards with a mat for landing. In the modern era, athletes run towards the bar and use the Fosbury Flop method of jumping, leaping head first with their back to the bar, performed since ancient times, competitors have introduced increasingly more effective techniques to arrive at the current form. The discipline is, alongside the pole vault, one of two vertical clearance events to feature on the Olympic athletics programme and it is contested at the World Championships in Athletics and IAAF World Indoor Championships, and is a common occurrence at track and field meetings. The high jump was among the first events deemed acceptable for women, Javier Sotomayor is the current mens record holder with a jump of 2.45 m set in 1993 – the longest standing record in the history of the mens high jump. Stefka Kostadinova has held the world record at 2.09 m since 1987. The rules for the jump are set internationally by the International Association of Athletics Federations. Jumpers must take off on one foot, a jump is considered a failure if the bar is dislodged by the action of the jumper whilst jumping or the jumper touches the ground or breaks the plane of the near edge of the bar before clearance. The technique one uses for the jump must be almost flawless in order to have a chance of clearing a high bar, competitors may begin jumping at any height announced by the chief judge, or may pass, at their own discretion. Three consecutive missed jumps, at any height or combination of heights, the victory goes to the jumper who clears the greatest height during the final. If two or more tie for first place, the tie-breakers are, 1) The fewest misses at the height at which the tie occurred. If the event remains tied for first place, the jumpers have a jump-off, the bar is then alternately lowered and raised until only one jumper succeeds at a given height. The first recorded high jump event took place in Scotland in the 19th century, early jumpers used either an elaborate straight-on approach or a scissors technique. In the later years, the bar was approached diagonally, around the turn of the 20th century, techniques began to modernise, starting with the Irish-American Michael Sweeneys Eastern cut-off. By taking off like the scissors, but extending his back and flattening out over the bar, Sweeney achieved a more economic clearance, another American, George Horine, developed an even more efficient technique, the Western roll. In this style, the bar again is approached on a diagonal, Horine increased the world standard to 2.01 m in 1912. His technique was predominant through the Berlin Olympics of 1936, in which the event was won by Cornelius Johnson at 2.03 m, American and Soviet jumpers held the playing field for the next four decades, and they pioneered the evolution of the straddle technique. Straddle jumpers took off as in the Western roll, but rotated their torso around the bar, straddle-jumper Charles Dumas was the first to clear 7 feet, in 1956, and American John Thomas pushed the world mark to 2.23 m in 1960
9.
Show jumping
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Show jumping, also known as stadium jumping, open jumping, or simply jumping, is a part of a group of English riding equestrian events that also includes dressage, eventing, hunters, and equitation. Jumping classes are seen at horse shows throughout the world. International competitions are governed by the rules of the International Federation for Equestrian Sports, Show jumping events have hunter classes, jumper classes and hunt seat equitation classes. Hunters are judged subjectively on the degree to which they meet a standard of manners, style. Jumper courses tend to be more complex and technical than hunter courses because riders. Courses often are colorful and at times, quite creatively designed, hunters have meticulous turnout and tend toward very quiet, conservative horse tack and rider attire. Hunter bits, bridles, crops, spurs, and martingales are tightly regulated, formal turnout always is preferred, a neat rider gives a good impression at shows. In addition to hunters and jumpers, there are classes, sometimes called hunt seat equitation. The equipment, clothing, and fence styles used in more closely resemble hunter classes. Jumper classes are held over a course of show jumping obstacles, including verticals, spreads, the intent is to jump cleanly over a set course within an allotted time. Time faults are assessed for exceeding the time allowance, Jumping faults are incurred for knockdowns and blatant disobedience, such as refusals. Horses are allowed a number of refusals before being disqualified. A refusal may lead to a rider exceeding the time allowed on course, placings are based on the lowest number of points or faults accumulated. A horse and rider who have not accumulated any jumping faults or penalty points are said to have scored a clear round. Tied entries usually have a jump-off over a raised and shortened course, and the course is timed, if entries are tied for faults accumulated in the jump-off, the fastest time wins. In most competitions, riders are allowed to walk the initial course, going off course will cost time if minor errors are made and major departures will result in disqualification. The higher levels of competition, such as A or AA rated shows in the United States, or the international Grand Prix circuit, present more technical and complex courses. Not only is the height and width of an obstacle increased to present a challenge, technical difficulty also increases with tighter turns
10.
Bottlenose dolphin
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Bottlenose dolphins, the genus Tursiops, are the most common and well-known members of the family Delphinidae, the family of oceanic dolphin. Recent molecular studies show the genus contains two species, the bottlenose dolphin and the Indo-Pacific bottlenose dolphin, instead of one. Research in 2011 revealed a species, the Burrunan dolphin. Bottlenose dolphins inhabit warm and temperate seas worldwide and they live in all oceans except for the Arctic and Antarctic Circle area. Bottlenose dolphins live in groups typically of 10–30 members, called pods and their diets consist mainly of forage fish. Dolphins often work as a team to harvest fish schools, Dolphins search for prey primarily using echolocation, which is similar to sonar. They emit clicking sounds and listen for the echos to determine the location and shape of nearby items. Numerous investigations of bottlenose dolphin intelligence have been conducted, examining mimicry, use of language, object categorization. They can use tools and transmit cultural knowledge across generations, Bottlenose dolphins gained popularity from aquarium shows and television programs such as Flipper. They have also trained by militaries to locate sea mines or detect. In some areas, they cooperate with local fishermen by driving fish into their nets, some encounters with humans are harmful to the dolphins, people hunt them for food, and dolphins are killed inadvertently as a bycatch of tuna fishing and by getting caught in crab traps. The deepest dive ever recorded for a dolphin was 300 meters. This was accomplished by Tuffy, a dolphin trained by the US Navy, scientists were long aware that Tursiops dolphins might consist of more than one species. Molecular genetics allowed much greater insight into this previously intractable problem, truncatus lives in the Black Sea, The Pacific bottlenose dolphin, another subspecies of T. truncatus and T. aduncus, but is not considered a separate species by the IUCN. The two ecotypes of the bottlenose dolphin within the western North Atlantic are represented by the shallower water or coastal ecotype. Their ranges overlap, but they have shown to be genetically distinct. They are not currently described, however, as species or subspecies. In general, genetic variation between populations is significant, even nearby populations
11.
Dog
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The domestic dog is a member of genus Canis that forms part of the wolf-like canids, and is the most widely abundant carnivore. The dog and the extant gray wolf are sister taxa, with modern wolves not closely related to the wolves that were first domesticated, the dog was the first domesticated species and has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes. Their long association with humans has led dogs to be attuned to human behavior. Dogs vary widely in shape, size and colours, dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship and, more recently, aiding handicapped individuals. This influence on society has given them the sobriquet mans best friend. The term domestic dog is used for both domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, the term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce. The word also shows the familiar petname diminutive -ga also seen in frogga frog, picga pig, stagga stag, wicga beetle, worm, the term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary. In 14th-century England, hound was the word for all domestic canines, and dog referred to a subtype of hound. It is believed this dog type was so common, it became the prototype of the category hound. By the 16th century, dog had become the general word, the word hound is ultimately derived from the Proto-Indo-European word *kwon-, dog. This semantic shift may be compared with in German, where the corresponding words Dogge, a male canine is referred to as a dog, while a female is called a bitch. The father of a litter is called the sire, and the mother is called the dam, the process of birth is whelping, from the Old English word hwelp, the modern English word whelp is an alternate term for puppy. A litter refers to the offspring at one birth which are called puppies or pups from the French poupée, doll. The term dog typically is applied both to the species as a whole, and any male member of the same. An adult female is a bitch, in some countries, especially in North America, dog is used instead due to the vulgar connotation of bitch. An adult male capable of reproduction is a stud, an adult female capable of reproduction is a brood bitch, or brood mother. Immature males or females are pups or puppies, a group of pups from the same gestation period is a litter
12.
Muscle contraction
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Muscle contraction is the activation of tension-generating sites within muscle fibers. The termination of muscle contraction is followed by muscle relaxation, which is a return of the fibers to their low tension-generating state. Muscle contractions can be described based on two variables, length and tension, a muscle contraction is described as isometric if the muscle tension changes but the muscle length remains the same. In contrast, a muscle contraction is isotonic if muscle length changes, if the muscle length shortens, the contraction is concentric, if the muscle length lengthens, the contraction is eccentric. In natural movements that underlie locomotor activity, muscle contractions are multifaceted as they are able to produce changes in length, therefore, neither length nor tension is likely to remain the same in muscles that contract during locomotor activity. In vertebrates, skeletal muscle contractions are neurogenic as they require synaptic input from neurons to produce muscle contractions. A single motor neuron is able to innervate multiple muscle fibers, once innervated, the protein filaments within each skeletal muscle fiber slide past each other to produce a contraction, which is explained by the sliding filament theory. The contraction produced can be described as a twitch, summation, or tetanus, in skeletal muscles, muscle tension is at its greatest when the muscle is stretched to an intermediate length as described by the length-tension relationship. Unlike skeletal muscle, the contractions of smooth and cardiac muscles are myogenic, the mechanisms of contraction in these muscle tissues are similar to those in skeletal muscle tissues. Muscle contractions can be described based on two variables, force and length, force itself can be differentiated as either tension or load. Muscle tension is the force exerted by the muscle on an object whereas a load is the force exerted by an object on the muscle, when muscle tension changes without any corresponding changes in muscle length, the muscle contraction is described as isometric. If the muscle length changes while muscle tension remains the same, in an isotonic contraction, the muscle length can either shorten to produce a concentric contraction or lengthen to produce an eccentric contraction. Furthermore, if the muscle length shortens, the contraction is concentric, but if the muscle length lengthens, then the contraction is eccentric. In natural movements that underlie locomotor activity, muscle contractions are multifaceted as they are able to produce changes in length, therefore, neither length nor tension is likely to remain constant when the muscle is active during locomotor activity. An isometric contraction of a muscle generates tension without changing length, an example can be found when the muscles of the hand and forearm grip an object, the joints of the hand do not move, but muscles generate sufficient force to prevent the object from being dropped. In isotonic contraction, the tension in the muscle remains constant despite a change in muscle length and this occurs when a muscles force of contraction matches the total load on the muscle. In concentric contraction, muscle tension is sufficient to overcome the load, and this occurs when the force generated by the muscle exceeds the load opposing its contraction. During a concentric contraction, a muscle is stimulated to contract according to the sliding filament theory and this occurs throughout the length of the muscle, generating a force at the origin and insertion, causing the muscle to shorten and changing the angle of the joint
