Biomechanics of Running Essay

This essay has a total of 1398 words and 8 pages.

Biomechanics of Running

Introduction: A Qualitative Analysis of Running
In the 1970's, thousands of people took to the road with a new trend of
exercise----running. It was fairly easy; just put one foot in front of the other as fast
as you can and go as far as you can. Feel the burn in your chest? The sweat trickling down
your face? The throb in your knees as your foot pounds into the ground with every step?
Well then, you're exercising! You're running! Since then, running has become a dominant
factor in sports and fitness; a factor so prevalent that the number of musculoskeletal
injuries due to running has also increased over the last quarter century. These chronic
injuries are usually due to overuse, improper training techniques, or a combination of the
two. By using the results of other biomechanists' studies, one can extrapolate an idea of
what running should look like and what muscles are utilized during the activity.
Consequently, changes in technique, strength training, and flexibility training can be
made in order to decrease the potential for injury.

Article Summaries
Before analyzing the mechanics of running, it is important to accumulate some of the vast
research available for this activity. The following are brief summaries of research
articles that study various factors on running.

DeVita (1994) noted the gait cycle is measured in two ways: swing-stance-swing or
stance-swing-stance. In this study, EMG activity of six muscles was obtained from four
subjects while walking and running. The data was collected while the subjects performed a
consecutive swing, stance, swing period of each gait. From this, the swing-to-stance and
stance-to-swing period of each gait could be measured. The EMG results showed greater
activation levels for 5/6 muscles during the swing-to-stance period. Results concluded
that the subjects needed to prepare for the initiation of stance and the application of
relatively large external forces and momentums. Therefore, when assessing the human gait,
it is best to observe stance-swing-stance.

Jacobs, Bobbert, VanIngen, and Schenau (1993) analyzed the function of mono- and
biarticular leg muscles during the stretch-shortening cycle of running at 6 m/s.
Kinematics, ground reaction forces and EMG activities were recorded for a single stance
phase. First of all, estimates of muscle force were correlated with origin-to-insertion
velocity (VOI). Second, a model of the soleus and gastrocnemius was used to find the
active state and internal muscle behaviors. High correlations were found between the
muscle forces and the VOI time curves for the monoarticular hip, knee and ankle extensor
muscles. However, the correlations for the biarticular muscles were low. The results from
the model concluded that the active state of the gastrocnemius was high during the stretch
phase; the active state of the soleus started out low during the stretch phase, but
reached a higher plateau as the stretch phase ended and the shortening phase began.
Therefore, the difference in stimulation is a compromise between minimizing energy
dissipation and optimal use of the stretch-shortening cycle.

Nig, DeBoer, and Fisher (1995) did a comparison of treadmill and overground running.
Twenty-two subjects ran on four different surfaces: overground and three treadmills, each
varying in size and power. Each subject was filmed in the sagittal and frontal (posterior)
plane. Body landmarks were placed on the superior border of the greater trochanter, the
lateral femoral epicondyle, the lateral malleolus, and the head of the fifth metatarsal of
the right leg. Subjects ran at four different speeds varying from 3.0-6.0 m/s. It was
concluded that the subjects systematically planted their feet in a flatter position on the
treadmill than overground. Therefore, using a treadmill for running assessment can lead to
inadequate conclusions about overground running.

Anatomical Analysis
According to Thordarson (1997), running can be analyzed by measuring the gait cycle, or
the initial contact of one foot to the following initial contact of the same foot, which
is broken down into two phases: stance and swing. The stance phase constitutes
approximately 40% of the running gait cycle, depending on the velocity of the runner.
Moreover, it consists of initial contact of the heel with the ground, the shifting of the
body's weight, and bringing the toe off the ground; therefore, the stance phase can be
divided into two subphases, absorption and propulsion, which are separated by midstance.
The swing phase, approximately 60% of the gait cycle, begins with the toe leaving the
ground, the lower extremity decelerating upward, and then accelerating downward. This
phase is also divided into two subphases, initial swing and terminal swing, which are
separated by midswing. Figure 1 below shows the breakdown of the running gait cycle.

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