Jumps

JUMPS from a biomechanical point of view consist in the fact that through the sharp straightening (extending) of the legs, the body is given accelerated upward movement (exceeding the acceleration of its downward movement under the influence of gravity), thanks to which the body is thrown upward from the ground. Thus in jumping the body itself acts as a spring. In jumps one can distinguish 4 basic moments: 1) preparation for the jump - bending of the legs to a certain limit in the hip, knee, and ankle joints, which is necessary in order for the extensors to be provided with some relaxation (impossible when the legs are extended) and thereby a greater volume for subsequent contraction; 2) the jump itself - a sharp, short contraction of the extensors, ending with a push (with the toes) from the ground; 3) free flight, during which the body moves along a parabola, and the trunk and extremities assume the position most advantageous for a given jump (for example, for overcoming an obstacle, for landing); 4) landing - descent as a rule on the toes, short bending and subsequent straightening of the body. Depending on the particular characteristics of the jump, the detailed movements during these 4 moments may be different. The main work in jumping thus falls on the muscles of the lower extremities (mainly the extensors), the musculature of the pelvis, and the straight muscles of the abdomen. Moreover, even in jumps that do not require direct assistance from the upper extremities (e.g., support on an obstacle), the musculature of the latter, along with the muscles of the trunk, takes an active part in the coordinated work of the entire body, helping the push (run-up, 'swing'), giving the body the most advantageous position during flight, and finally maintaining balance when landing. In children, jumping is a favorite form of movement in play, almost as common as running. With insufficient physical education in later years, the ability to jump disappears and for adults they often represent one of the difficult physical exercises. In physical education, jumping finds wide application in the most diverse forms and types. Conventionally, jumps can be divided into 2 main groups: 1) jumps as a component element of a complex exercise (often determining the main value of the entire exercise and its load), e.g., in many of the mobile games, in sports games, in some gymnastic exercises on apparatus, in obstacle running, in boxing, in fencing, in figure skating, etc. 2) jumps as an independent exercise in general developmental, preparatory (training), and sports gymnastics (starting with simple hops and ending with jumps over apparatus), in applied military gymnastics, in various sports - in track and field, on skis, into water, etc. By the general character of execution, jumps are divided into free and supported, by form - into 4 types: in length, in height, jumps upward and jumps downward (jumps into depth). Jumps are performed over apparatus (e.g., horse, vaulting box, bars, etc.), with apparatus (e.g., with a pole), from a smooth surface and from a springboard (a device that enhances the push). Results in sports jumps mainly depend on the technique of their execution - correct run-up, energy of the push, correct position of the body during flight, etc. Great importance for good results (this is especially evident in track and field jumps) is also had by the characteristics of physical development: the 'sports type' of jumpers is distinguished by long, well-developed lower extremities with great height and small body weight. By the nature of the load on the body, jumps can be classified as intensive in most cases short physical exercises, associated with significant but usually quickly passing excitation of the cardiovascular system and respiration. Dosed and technically simple jumps are used as special exercises training and checking the condition of these systems (e.g., exercise with a rope in a boxer's training, functional test of the cardiovascular system with hops). In addition to their great value as means of physical development, particularly in developing coordination of movements, many of them also have important significance from the point of view of cultivating decisiveness, courage, as well as acquiring applied military skills needed for rapid overcoming of natural and artificial obstacles in combat conditions. Therefore, jumps in various forms are included in the curriculum of physical education classes in schools and industrial physical education groups, in physical training classes in the Red Army, as well as in the program of the complex of practical tests for the All-Union physical culture badge 'Ready for Labor and Defense'. Jumps belong to the number of physical exercises associated with rather frequent various types of injuries (the most common of them - sprain in the ankle joint). Preventive measures against injury: methodologically correct transition from simple to complex exercise (mastery of jumping technique), 'spotting' when jumping over apparatus, sufficient softness of the ground, presence of mats in landing areas, etc. Jumps associated with great shaking of the body when landing (e.g., skiing jumps, triple jump in track and field, etc.) should be completely excluded for women due to the possible harmful effect of these jumps on the sexual organs.

N. Bunkin.