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Horse Running - Edward Muybridge
Running is defined as the fastest means for an animal to move on foot.[citation needed] It is defined in sporting terms as a gait in which at some point all feet are off the ground at the same time.
Human running mechanics
Running is a complex and coordinated process that involves the
entire body. Every human being runs differently, but certain general
features of running motion are common.
Lower body motion
Running is executed as a sequence of strides, which alternate
between the two legs. Each leg's stride can be roughly divided into
three phases: support, drive, and recovery. Support and drive occur
when the foot is in contact with the ground. Recovery occurs when the
foot is off the ground. Since only one foot is on the ground at a time
in running, one leg is always in recovery, while the other goes through
support and drive. Then, briefly, as the runner leaps through the air,
both legs are in recovery. These phases are described in detail below.
Support
During the support phase, the foot is in contact with the ground and
supports the body against gravity. The body's centre of mass is
typically somewhere in the lower abdominal area between the hips. The
supporting foot touches ground slightly ahead of the point that lies
directly below the body's centre of mass. The knee joint is at its
greatest extension just prior to the support phase; when contact is
made with the ground, the knee joint begins to flex. To what extent it
flexes varies with the running style. There exist stiff-legged running
styles which reduce knee flexion, and looser, or more dynamic running
styles which increase it. As the supporting leg bends at the knee, the
pelvis dips down on the opposite side. These motions absorb shock and
are opposed by the coordinated action of several muscles. The pelvic
dip is opposed by the Tensor fasciae lataeilio-tibial band of the
supporting leg, the hip abductor, and the abdominals and lower back
muscles. The knee flexion is opposed by the Muscle contraction eccentric contraction
of the quadriceps muscle. The supporting hip continues to extend and
the body's centre of mass passes over the supporting leg. The knee then
begins to extend, and the opposite hip rises from its brief dip. The
support phase begins to transition into drive.
Drive
The support phase quickly transitions into the drive phase. The
drive leg extends at the knee joint, and at the hips, such that the toe
maintains contact with the ground as that leg trails behind the body.
The foot pushes backward and also down, creating a diagonal force
vector, which, in an efficient running style, is aimed squarely at the
runner's centre of mass. Since the diagonal vector has a vertical
component, the drive phase continues to provide some support against
gravity and can be regarded as an extension of the support phase.
During the drive, the foot may extend also, by a flexing of the soleus and gastrocnemius
muscle in the calf. In some running styles, notably long-distance
"shuffles" which keep the feet close to the ground, the ankle remains
more or less rigid during drive. Because the knee joint straightens,
though not completely, much of the power of the drive comes from the quadriceps
muscle group, and in some running styles, additional power comes from
the calves as they extend the foot for a longer drive. This motion is
most exhibited in sprinting.
Recovery
When the driving toe loses contact with the ground, the recovery
phase begins. During recovery, the hip flexes, which rapidly drives the
knee forward. Much of the motion of the lower leg is driven by the
forces transferred from the upper leg rather than by the action of the
muscles. As the knee kicks forward, it exerts torque
against the lower leg through the knee joint, causing the leg to snap
upward. The degree of leg lift can be consciously adjusted by the
runner, with additional muscle power. During the last stage of
recovery, the hip achieves maximal flexion, and, as the lower leg
rapidly unfolds, which it does in a passive way, the knee joint also
reaches its greatest, though not full, extension. During this extension
of the leg and flexion of the hip, the hamstring and gluteal muscles
are required to rapidly stretch. Muscles which are stretched respond by
contracting by a reflex action. Recovery ends when the foot comes into contact with the ground, transitioning again into the support phase.
Upper body motion
The motions of the upper body are essential to maintaining balance
and a forward motion for optimal running. They compensate for the
motions of the lower body, keeping the body in rotational balance. A
leg's recovery is matched by a forward drive of the opposite arm, and a
leg's support and drive motions are balanced by backward movement of
the opposite arm. The shoulders and torso are also involved. Because
the leg drive is slower than the kick of recovery, the arm thrusting
backward is slower also. The forward arm drive is more forceful and
rapid.
The more force exerted by the lower body, the more exaggerated do
the upper body motions have to be to absorb the momentum. While it is
possible to run without movements of the arms, the spine and shoulders
will generally still be recruited. Using the arms to absorb the forces
aids in maintaining balance at higher speed. Otherwise, optimal force
would be hard to attain for fear of falling over.
Most of the energy expended in running goes to the compensating
motions, and so considerable gains in running speed as well as economy
can be made by eliminating wasteful or incorrect motions.
For instance, if the force vector in the drive phase is aimed too
far away from the centre of mass of the body, it will transfer an
angular momentum to the body which has to be absorbed. If a free body
in space is struck off-centre by a projectile, it will rotate as well
as recoil. If the projectile strikes the body's centre of mass exactly,
the object will recoil only, without rotating.
The faster the running, the more energy has to be dissipated through
compensating motions throughout the entire body. This is why elite
sprinters have powerful upper body physiques. As the competitive
distance increases, there is a rapid drop in the upper body and overall
muscle mass typically exhibited by the people who compete at a high
level in each respective event.
Elements of good running technique
Upright posture and a slight forward lean
Leaning forward places a runner's center of mass on the front part
of the foot, which avoids landing on the heel and facilitates the use
of the spring mechanism of the foot. It also makes it easier for the
runner to avoid landing the foot in front of the center of mass and the
resultant braking effect.
Stride rate
Exercise physiologists have found that the stride rates are
extremely consistent across professional runners, between 185 and 200
steps per minute. The main difference between long- and short-distance
runners is the length of stride rather than the rate of stride.[1][2]
During running, the speed at which the runner moves may be calculated by multiplying the cadence (steps per second) by the stride length. Running is often measured in terms of pace[3] in minutes per mile or kilometer.
Running versus walking
In walking, one foot is always in contact with the ground, the legs
are kept mostly straight and the center of gravity rides along fairly
smoothly on top of the legs; in comparison, humans actually jump from
one leg to the other while running. Each jump raises the center of
gravity during take-off, and lowers it on landing as the knee bends to
absorb the shock. At mid arc, both feet are momentarily off of the
ground. This continual rise and fall of bodyweight expends a tremendous
amount of energy opposing gravity and absorbing shock during take-off
and landing.[4]
. The act of running involves using more energy to accomplish travel
over the same distance and running is a less efficient means of
locomotion in terms of calories expended, though it is faster.
Running injuries
Due to its high-impact nature, there are many injuries associated with running. Common injuries include "runner's knee" (pain in the knee), shin splints, pulled muscles (especially the hamstring), "jogger's nipple" (irritation of the nipple due to friction), twisted ankles, iliotibial band syndrome, plantar fasciitis, and Achilles tendinitis. Stress fractures
are also fairly common in runners training at a high volume or
intensity. The most common running-related injuries are due to
over-exertion or bad running form.[citation needed]
Repetitive stress on the same tissues without enough time for recovery
or running with improper form can lead to many of the above. Generally
these injuries can be minimized by warming up beforehand, wearing proper running shoes, improving running form, performing strength training exercises, eating a well balanced diet, getting enough rest
and "icing" (applying ice to sore muscles, or taking an ice bath). Ice
immersion is a very effective modality in the treatment of subacute
injuries or inflammation, muscular strains, and overall muscular
soreness. For runners in particular, ice baths offer two distinct
improvements over traditional techniques. First, immersion allows
controlled, even constriction around all muscles, effectively closing
microscopic damage that cannot be felt and numbing the pain that can.
One may step into the tub to relieve sore calves, but quads, hams, and
connective tissues from hips to toes will gain the same benefits,
making hydrotherapy an attractive preventive regimen. Saint Andrew’s
cross-country coach John O’Connell, a 2:48 masters marathoner, will hit
the ice baths before the ibuprofen. "Pain relievers can disguise
injury," he warns. "Ice baths treat both injury and soreness." The
second advantage involves a physiological reaction provoked by the
large amount of muscle submerged. Assuming one has overcome the mind’s
initial flight response in those first torturous minutes, the body
fights back by invoking a "blood rush." This rapid transmission
circulation flushes the damage-inflicting waste from the system, while
the cold water on the outside preserves contraction. Like an oil change
or a fluid dump, the blood rush revitalizes the very areas that demand
fresh nutrients. Make sure not to stay in any longer than 15 minutes;
10 minutes is usually sufficient. There is a strong consensus among the
running and scientific community that all of those can be effective in
both minimizing and recovering from running injuries.[citation needed]
Another injury prevention method common in the running community is stretching.
Stretching is often recommended as a requirement to avoid running
injuries, and it is almost uniformly performed by competitive runners
of any level. Recent medical literature, however, finds mixed effects
of stretching prior to running. One study found insufficient evidence
to support the claim that stretching prior to running was effective in
injury prevention or soreness reduction,[5].
Another, however, has demonstrated that stretching prior to running
increases injuries, while stretching afterwards actually decreases them.[6]
The American College of Sports Medicine recommends that all stretching
be done after exercise, this is when the muscles are most warmed up and
capable of increasing flexibility. Recent studies have also shown that
stretching will reduce the amount of strength the muscle can produce
during that training session.
Inconsistent experimental methodology and the failure to use proper
stretching methods are reasons given to explain the conflicting results[citation needed]. Because of this, members of the running community argue that stretching remains helpful.[citation needed]
Running benefits
While there is the potential for injury in running (just as there is
in any sport), there are many benefits. Some of these benefits include
potential weight loss, cardiovascular health, increased muscle mass,
increased bone density, and an improved emotional state. Following a
consistent routine of running can increase HDL levels, reducing the
risks of cardiovascular disease. Running, like all forms of regular exercise, can effectively slow or reverse the effects of aging.
Jogging
-
Jogging is a vaguely-defined term which generally refers to a
type of slow running, which may have originated in the UK. Previously
called "roadwork" in the US when athletes in training, such as boxers,
customarily ran several miles each day as part of their conditioning,
in the 1960s to 1970s the word "roadwork" was mostly supplanted by the
word "jogging," as the activity gained popularity.
The term jogging has fallen out of favour in recent years.[citation needed]
Slower recreational runners now refer to themselves as "runners",
rather than joggers. Jogging tends to imply that the runner is not
trying whereas running implies someone at speed. The informal term
"penguin running" has been adopted by many[citation needed]. The term "penguin" was coined by John Bingham.
Running as a sport
Running is both a competition and a type of training for sports which have running or endurance
components. As a sport it is split into events divided by distance and
sometimes includes permutations such as the obstacles in Steeplechase and hurdles.
Running races are contests to determine which of the competitors is
able to run a certain distance in the shortest time. Today, competitive
running events make up the core of the sport of athletics.
Events are usually grouped into several classes, each requiring
substantially different athletic strengths and involving different
tactics, training methods, and types of competitors.
Running competitions have probably existed for most of humanity's history, and were a key part of the ancient Olympic Games as well as the modern Olympics.
Today, road racing is a popular sport among non-professional athletes,
who included over 7.7 million people in America alone in 2002 [7].
Types of running events
Classification of running by distance
See also
References
- ^ Hoffman, K. (1971). "Stature, leg length and stride frequency". Track Technique 46: 1463–69.
- ^ Rompottie, K. (1972). "A study of stride length in running". International Track and Field: 249–56.
- ^ Pacing chart for running
- ^ Hall,
C., Figueroa, A, Fernhall, B & Kanaley, J.A. (2004) Energy
expenditure of walking and running: Comparison with prediction
equations. Medicine & Science in Sport & Exercise, 36 (12), 2128-2134. Abstract
- ^
Herbert, R.D. & Gabriel, M. (2002). Effects of stretching before
and after exercising on muscle soreness and risk of injury: systematic
review. British Medical Journal, 325 p. 468. online
- ^ Stretching and running injuries
- ^ USA Track & Field (2003). "Long Distance Running - State of the Sport."
External links
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