Running Man Ep 94 Eng Sub 720p Or 1080p
Antonette Hespe
Running is a method of terrestrial locomotion allowing humans and other animals to move rapidly on foot. Running is a type of gait characterized by an aerial phase in which all feet are above the ground (though there are exceptions).[1] This is in contrast to walking, where one foot is always in contact with the ground, the legs are kept mostly straight and the center of gravity vaults over the stance leg or legs in an inverted pendulum fashion.[2] A feature of a running body from the viewpoint of spring-mass mechanics is that changes in kinetic and potential energy within a stride co-occur, with energy storage accomplished by springy tendons and passive muscle elasticity.[3] The term running can refer to any of a variety of speeds ranging from jogging to sprinting.
It is hypothesized that the ancestors of humankind developed the ability to run for long distances about 2.6 million years ago, probably to hunt animals.[5][6] Competitive running grew out of religious festivals in various areas. Records of competitive racing date back to the Tailteann Games in Ireland between 632 BCE and 1171 BCE,[7][8][9] while the first recorded Olympic Games took place in 776 BCE. Running has been described as the world's most accessible sport.[10]
Early humans most likely developed into endurance runners from the practice of persistence hunting of animals, the activity of following and chasing until a prey is too exhausted to flee, succumbing to "chase myopathy" (Sears 2001), and that human features such as the nuchal ligament, abundant sweat glands, the Achilles tendons, big knee joints and muscular glutei maximi, were changes caused by this type of activity (Bramble & Lieberman 2004, et al.).[12][13][14] The theory as first proposed used comparative physiological evidence and the natural habits of animals when running, indicating the likelihood of this activity as a successful hunting method. Further evidence from observation of modern-day hunting practices also indicated this likelihood (Carrier et al. 1984).[14][15] According to Sears (p. 12) scientific investigation (Walker & Leakey 1993) of the Nariokotome skeleton provided further evidence for the Carrier theory.[16]
Competitive running grew out of religious festivals in various areas such as Greece, Egypt, Asia, and the East African Rift in Africa. The Tailteann Games, an Irish sporting festival in honor of the goddess Tailtiu, dates back to 1829 BCE and is one of the earliest records of competitive running.[17] The origins of the Olympics and Marathon running are shrouded by myth and legend, though the first recorded games took place in 776 BCE.[18] Running in Ancient Greece can be traced back to these games of 776 BCE.
...I suspect that the sun, moon, earth, stars, and heaven, which are still the gods of many barbarians, were the only gods known to the aboriginal Hellenes. Seeing that they were always moving and running, from their running nature they were called gods or runners (Thus, Theontas)...
Running gait can be divided into two phases regarding the lower extremity: stance and swing.[20][21][22][23] These can be further divided into absorption, propulsion, initial swing, and terminal swing. Due to the continuous nature of running gait, no certain point is assumed to be the beginning. However, for simplicity, it will be assumed that absorption and footstrike mark the beginning of the running cycle in a body already in motion.
Most recent research, particularly regarding the footstrike debate, has focused solely on the absorption phases for injury identification and prevention. The propulsion phase of running involves the movement beginning at midstance until toe off.[21][22][28] From a full stride length model however, components of the terminal swing and footstrike can aid in propulsion.[23][29]Set up for propulsion begins at the end of the terminal swing as the hip joint flexes, creating the maximal range of motion for the hip extensors to accelerate through and produce force. As the hip extensors change from reciporatory inhibitors to primary muscle movers, the lower extremity is brought back toward the ground, although aided greatly by the stretch reflex and gravity.[23] Footstrike and absorption phases occur next with two types of outcomes. This phase can be only a continuation of momentum from the stretch reflex reaction to hip flexion, gravity, and light hip extension with a heel strike, which does little to provide force absorption through the ankle joint.[28][30][31] With a mid/forefoot strike, loading of the gastro-soleus complex from shock absorption will serve to aid in plantar flexion from midstance to toe-off.[31][32]As the lower extremity enters the midstance, actual propulsion begins.[28] The hip extensors continue contracting with help from the acceleration of gravity and the stretch reflex left over from maximal hip flexion during the terminal swing phase. Hip extension pulls the ground underneath the body, pulling the runner forward. During midstance, the knee should be in some degree of knee flexion due to elastic loading from the absorption and footstrike phases to preserve forward momentum.[33][34][35] The ankle joint is in dorsiflexion at this point underneath the body, either elastically loaded from a mid/forefoot strike or preparing for stand-alone concentric plantar flexion.All three joints perform the final propulsive movements during toe-off.[28][30][31][32] The plantar flexors plantar flex, pushing off from the ground and returning from dorsiflexion in midstance. This can either occur by releasing the elastic load from an earlier mid/forefoot strike or concentrically contracting from a heel strike. With a forefoot strike, the ankle and knee joints release their stored elastic energy from the footstrike/absorption phase.[33][34][35] The quadriceps group/knee extensors go into full knee extension, pushing the body off of the ground. At the same time, the knee flexors and stretch reflex pull the knee back into flexion, adding to a pulling motion on the ground and beginning the initial swing phase. The hip extensors extend to the maximum, adding the forces pulling and pushing off of the ground. The hip extensors' movement and momentum also contribute to knee flexion and the beginning of the initial swing phase.
Initial swing is the response of both stretch reflexes and concentric movements to the propulsion movements of the body. Hip flexion and knee flexion occur, beginning the return of the limb to the starting position and setting up for another foot strike. The initial swing ends at midswing when the limb is again directly underneath the trunk, pelvis, and hip with the knee joint flexed and hip flexion continuing. Terminal swing then begins as hip flexion continues to the point of activation of the stretch reflex of the hip extensors. The knee begins to extend slightly as it swings to the anterior portion of the body. The foot then makes contact with the ground with a foot strike, completing the running cycle of one side of the lower extremity.Each limb of the lower extremity works opposite to the other. When one side is in toe-off/propulsion, the other hand is in the swing/recovery phase preparing for footstrike.[20][21][22][23] Following toe-off and the beginning of the initial swing of one side, there is a flight phase where neither extremity is in contact with the ground due to the opposite side finishing terminal swing. As the footstrike of the one hand occurs, the initial swing continues. The opposing limbs meet with one in midstance and midswing, beginning the propulsion and terminal swing phases.
Recent research into various forms of running has focused on the differences in the potential injury risks and shock absorption capabilities between heel and mid/forefoot footstrikes. It has been shown that heel striking is generally associated with higher rates of injury and impact due to inefficient shock absorption and inefficient biomechanical compensations for these forces.[24] This is due to pressures from a heel strike traveling through bones for shock absorption rather than being absorbed by muscles. Since bones cannot disperse forces easily, the forces are transmitted to other parts of the body, including ligaments, joints, and bones in the rest of the lower extremities up to the lower back.[37] This causes the body to use abnormal compensatory motions in an attempt to avoid serious bone injuries.[38] These compensations include internal rotation of the tibia, knee, and hip joints. Excessive compensation over time has been linked to a higher risk of injuries in those joints and the muscles involved in those motions.[30] Conversely, a mid/forefoot strike has been associated with greater efficiency and lower injury risk due to the triceps surae being used as a lever system to absorb forces with the muscles eccentrically rather than through the bone.[24] Landing with a mid/forefoot strike has also been shown to properly attenuate shock and allow the triceps surae to aid in propulsion via reflexive plantarflexion after stretching to absorb ground contact forces.[29][39] Thus a mid/forefoot strike may aid in propulsion.However, even among elite athletes, there are variations in self-selected footstrike types.[40] This is especially true in longer distance events, where there is a prevalence of heel strikers.[41] There does tend however to be a greater percentage of mid/forefoot striking runners in the elite fields, particularly in the faster racers and the winning individuals or groups.[36] While one could attribute the faster speeds of elite runners compared to recreational runners with similar footstrikes to physiological differences, the hip, and joints have been left out of the equation for proper propulsion. This raises the question of how heel-striking elite distance runners can keep up such high paces with a supposedly inefficient and injurious foot strike technique.
Biomechanical factors associated with elite runners include increased hip function, use, and stride length over recreational runners.[36][42] An increase in running speeds causes increased ground reaction forces, and elite distance runners must compensate for this to maintain their pace over long distances.[43]These forces are attenuated through increased stride length via increased hip flexion and extension through decreased ground contact time and more energy being used in propulsion.[43][44][45] With increased propulsion in the horizontal plane, less impact occurs from the decreased force in the vertical plane.[46] Increased hip flexion allows for increased use of the hip extensors through midstance and toe-off, allowing for more force production.[28]The difference even between world-class and national-level 1500-m runners has been associated with more efficient hip joint function.[47] The increase in velocity likely comes from the increased range of motion in hip flexion and extension, allowing for greater acceleration and speed. The hip extensors and extension have been linked to more powerful knee extension during toe-off, contributing to propulsion.[36]Stride length must be appropriately increased with some degree of knee flexion maintained through the terminal swing phases, as excessive knee extension during this phase along with footstrike has been associated with higher impact forces due to braking and an increased prevalence of heel striking.[48] Elite runners tend to exhibit some degree of knee flexion at footstrike and midstance, which first serves to eccentrically absorb impact forces in the quadriceps muscle group.[47][49][50] Secondly it allows for the knee joint to contract concentrically and provides significant aid in propulsion during toe-off as the quadriceps group is capable of producing large amounts of force.[28]Recreational runners have been shown to increase stride length through increased knee extension rather than increased hip flexion, as exhibited by elite runners, which provides an intense braking motion with each step and decreases the rate and efficiency of knee extension during toe-off, slowing down speed.[42] Knee extension, however, contributes to additional stride length and propulsion during toe-off and is seen more frequently in elite runners as well.[36]