Biomechanics of Running
By:
Ian Golden
Part
I
What will follow is a discussion of running
form, or biomechanics. Historical and contemporary views on the
topic as well as a synthesized vision of a recommended whole will
be presented. Ultimately, it is possible that there is no more efficient
form aside from the one your body is finding at this moment for
quick, comfortable, injury-free running. That motion is the culmination
of genetics paired with years of physiological development guided
by your interests and societal demands. For most, some form of running
comes naturally. For some, what comes naturally may not necessarily
equate to the most economical method. What most individuals can
thus benefit from is refocusing on certain aspects of running biomechanics
that could be improved upon. It is the intent of this presentation
to explore a few of these areas.
Elements
and Foundations of Form
To achieve an introspection of ideal mechanics,
walk for a period over a hard surface while barefoot. Relax your
breathing, muscles and mind, and feel how your body moves without
the aid of artificial cushioning or structure.
How must you land to best absorb the weight
of your body? What must you do to move quicker? If you increase
the length of your stride so that your knee is fully extended when
you first contact the ground, where does your foot make contact
and how does it feel? If you stand tall and lean back, where do
you make first contact and does it feel more or less smooth. Conversely,
what happens if you lean forward with your back still straight?
Does it feel easier to swing your leg forward with a straight knee
or to kick your heel up toward your buttocks? How does it feel to
pump your arms faster than your legs are moving, and what changes
must you make if you continue to walk with your arms completely
fixed at your sides?
An ideal mechanical sequence will find
you landing toward the outside of your foot between the ball of
your foot and your heel with your knee slightly bent. The foot will
accommodate the weight of your body through transferring force into
the plantar fascia and smaller muscles of the foot, while creating
a stable platform through your metatarsal heads (balls of your feet).
The weight of impact is stored as energy in muscles and connective
tissue to be further transferred into propulsion in toeing-off over
the second toe. The ankles, knees, and hips are the hinges for the
lower body, providing the attachments and fulcrums for the muscles
of the lower body to promote flexion and extension while reducing
side to side movement. The trunk and upper body are held erect with
a degree of forward lean corresponding to speed or pace where an
increased lean translates to an increased fall with gravity and
need for stepping or turnover. The arms will swing at the shoulders
to minimize rotation of the trunk, held by the side with slight
variations in elbow flexion, and moving in sequence with the opposing
foot. The wrists are straight and the fingers relaxed with a slight
bend at each knuckle. Reflecting the symmetry of the body, the shoulders
are level and head erect with eyes looking forward.
Running is merely an extension and magnification
of walking. Strides increase from a range of 30 to 60 per minute
to an ideal range of 180 to 190 in transitioning from walking to
running. The float phase of a gait cycle increases substantially
and the amount of weight placed on one leg increases from approximately
75% while walking, to 250% while running. With increased downward
force comes the potential for increased plyometric loading of tendons
with resulting increased recoil forces available. There is an increase
in the forward lean of the trunk, and explosive forces generated
as larger and more powerful muscle groups such as the Gluteals and
hip flexors become activated. The elbows drive further and more
forcefully backward to generate the equal and opposite reaction
of the hip driving the leg forward. Increased downward and forward
forces are met with increased upward and forward reactive forces
that permit greater explosion out of the calf musculature at toe
off.
Each body part moves in sequence with
another, achieving the goal of moving forward under the rule that
every movement or force requires and elicits an equal and opposite
force. Muscle groups must be balanced throughout the body for strong
and effective postures and movement. What differentiates each runner
is their specific anatomical structure and physiological development.
An individual’s anatomical alignment, tendencies toward muscle
and tissue development, oxygen carrying capacity, limits of lactic
acid tolerance or utilization, as well as those demands which were
present during an individual’s development and current lifestyle
all play equal and critical roles in dictating running economy.
It may be difficult to alter one’s skeletal alignment, propensity
toward lesser or greater muscle mass, but oxygen carrying capacity,
lactate threshold, and biomechanics all offer degrees of modification.
Historical
Perspective
Part established by gene, part shaped
by demands during development, and part shaped by training, each
runner has a unique and identifiable form despite operating under
the same physiological parameters of every other runner.
Quoting an earlier work titled “Track
and Field Omnibook” by Ken Doherty, the Complete Runner indicates,
“a sound rule of thumb when it comes to running technique
is to leave it alone”. They further indicate that it wasn’t
that small form inefficiencies couldn’t be addressed, but
that gross and often aesthetically weighted aspects may be more
trouble than they were worth to correct when considering some the
flawed forms of some of the finest runner’s in the world.
Dougherty continued, “Do what comes naturally, as long as
‘naturally’ is mechanically sound. If it isn’t,
do what is mechanically sound until it comes naturally.” Citing
the coach of former Olympic miler Herb Elliot, Percy Cerutty, others
at the time believed that runners had lost their semblance to animals
with regard to running through evolution and development, and that
the focus should be on breaking back down motor elements and starting
anew with biomechanics.
Several elite coaches of the time fell
in between the opinions of Doherty and Cerutty, that biomechanics
weren’t necessarily the ultimate goal but that they could
be improved upon to enhance a runner’s capacity. Core parameters
of running mechanics included an adjustment of foot-fall and stride
length according to desired speed, maintaining an erect body to
maximize power and efficiency, and using the arms as critical elements
of balance and drive.
The complete runner uses the work of Toni
Nett, a photographer of elite runners who published Track Technique
in 1964 to address foot-fall and stride length, who referenced foot-planting
patterns as the only universally applicable techniques found. His
conclusion was that runners at all distances land first on the outside
edge of the foot and then roll inward as shock is absorbed. The
point at which the foot made contact was dependent upon pace, with
sprinters landing toward the toes, mid-distance runners at the meta-tarsal
arch area, and at heel for longer distances. Dependent also on pace
was the element of stride length.
Citing Bill Bowerman, legendary University
of Oregon coach, two fundamental rules for controlling stride-length:
the foot should strike after it has reached the farthest point of
advance and has actually started to swing back, and that the point
of contact should be directly under the knee and not in front of
it, and as nearly as possible squarely beneath the center of gravity.
According to Bowerman, both could be achieved by keeping the knees
slightly bent at all times. Further, by not over-striding, braking
forces attributed to landing on an outstretched would be minimized.
Regarding the body positions of distance
runners and sprinters alike, Bowerman and others including Cerutty
felt that the body should be positioned erect so as to center one’s
weight over the hips in order maximize the potential of the legs.
They further believed that the arms, when rhythmically used, would
be the driving force and engine for the legs to follow. Shoulders
were to be held straight, arms bent but not locked by the side,
arm swing linear with minimal chest crossing, wrists neutral with
fingers cupped but relaxed.
p. 230 – 241, The
Complete Runner 1st edition, 1974, Runner’s World
“The only sensible way to run is
your own, no matter how much it deviates from textbook style. Above
all, don’t try to land on the balls of your feet like a sprinter.
If you do, you’ll almost certainly hurt your Achilles tendons.
Instead, land on your heels and roll forward, pushing off with your
toes.”
p. 177, The Complete Book
of Running 1st edition, Jim Fixx, 1977
“For most runners, a shoe should be higher at the heel than
at the ball of the foot, so that the rear of the shoe lands first
and absorbs most of the body’s weight. A fairly thick heel
also minimizes stretching of the Achilles tendon, an important consideration
if you’re a woman and wear high heels much of the time.”
p. 121, Jim Fixx’s
Second Book of Running, 1980.
Contemporary
Theories
The
Pose Method (Dr. Nicholas Romanov, 1997)
The Pose Method focuses on achieving an
S-curved posture aligning the shoulders hips and ankles over the
base of support in the ball of the foot. With and from this pose,
energy is transferred quickly and rhythmically from one foot strike
to the next along a horizontal line using gravity for propulsion
with minimal active muscle recruitment.
Centering the body over its base of support,
runners are encouraged to assume a slight forward lean stemming
from the ankles. Allowing the body to fall forward, the supportive
foot is pulled from beneath and replaced by the opposing foot. Utilizing
gravity and pulling rather than pushing limits vertical displacement
and insures that propulsion remains horizontal. The impact force
that occurs in each foot is harnessed as plyometric or elastic energy
and used in propelling the body forward. Ground contact time should
be minimized, the foot lifted directly up beneath the body to initiate
stride recovery. The knees should be bent at all times and the feet
should always fall behind the knee at ground contact with heels
elevated. It should be noted that before any amount of prolonged
time is spent working on Pose techniques, several prior months should
be devoted to strengthening those muscles, tendons, and ligaments
required to run efficiently and injury free. Several exercise books,
videos, and posts are available to guide a runner through to injury-free
success with Pose Method running.
Critical points of application: hop on
one ball of the foot using hamstrings of opposite leg in quick pull
to generate hopping force; short hops and switches on alternating
legs between Pose position (head, hips and ankles aligned with slight
forward lean and heels elevated 1 inch); progress hopping to slight
forward progression; running in place using the hamstrings to pull
the foot up rather than quadriceps.
Chi
Running (Danny Dreyer, 2004)
The focus of Chi Running is on a postural
alignment that promotes the flow of energy, utilizing gravity rather
than relying on muscle strength for propulsion.
Its core posture brings the entire body
into an open alignment from the head, through the shoulders and
pelvis to the ankles. An erect but forward-leaning posture is maintained
and supported by alternating legs. The body’s core musculature
is used to maintain alignment between the upper and lower body,
using the effect of gravity in falling forward to promote varying
degrees of propulsion. Stride recovery should be initiated by lifting
the heel toward the buttocks and not by the knee and the lower leg
should be kept relaxed at all times. The arms should set the cadence
with a goal of 90 strides/minute (counting right or left foot only)
guided by intensity of driving the elbows back, keeping the wrists
neutral and hands relaxed above waistline at all times. The degree
of forward lean controls the speed to which the runner moves. Increased
speeds are provided by increased stride length, but cadence remains
the same.
Critical points of application: alignment
of body into Chi posture (1. hand over navel pulling down, other
hand under collarbone lifting up, in concert elongating or opening
chest 2. feet parallel 3. pull down with hand below navel while
applying pressure with back of other hand over sacrum, using abdominals
to lift and straighten pelvis); maintain opened Chi posture while
adding forward lean into wall through bending at ankles with heels
fixed; leaning with support, practice lifting at heel and driving
forward with the knee for circular leg motion that mimics a wheel;
progress to run with focus on 90 stride (both feet for total 180
foot strikes) cadence with quick heel lifts and rhythmic arms; goal
of running through sand pit with even undisturbed prints.
Evolution
Running (Ken Mierke, 2005)
Evolution running focuses on increasing
running economy, or the ability to move faster using less energy,
as well as injury resistance through biomechanics.
African runners have increasingly been
a dominating presence in mid and long distance running. They often
do not possess any advantages in oxygen or lactic acid processing
capacity, limb-length or height-weight ratio, or muscle fiber type
versus non-African runners. What has been found is greater efficiency
and injury resilience thought to be rooted in barefoot development.
Those individuals learning to run barefoot and thus more efficiently
are believed to continue doing so even after shoes are donned.
Emulating barefoot patterns entails running
with less vertical displacement, shortening stride length and increasing
stride rate to 180 foot strikes per minute (counting both feet).
With little vertical displacement, propulsion along the horizontal
plain is aided by the concerted effort of the hip flexor muscles
driving the knee forward and the hip extensors/gluteals propelling
the body forward. The prime sources of propulsion however are rooted
in gravity and plyometric energy. This energy is harnessed by landing
on the mid foot directly beneath the hips and center of mass and
in concert with the propulsion phase. Loading connective tissues
and muscles effectively loads a spring with energy stored for immediate
recoil. Harnessing plyometric energy reduces the demand on nutritional
energy stores and oxygen that drive muscles, does not require replenishing
and is thus not as susceptible to associated fatigue.
Critical points of application: standing
in place with feet together and knees slightly bent, practice hopping
1 inch into the air and landing on the forefoot with heel elevated,
feeling the use of elastic recoil rather than muscle activation;
standing next to and holding onto rail or partner for balance, extend
leg backward with knee straight, holding for 5 seconds to feel tension
in gluteals; also standing supported, swing one leg through with
knee slightly bent alternately driving knee forward and extending
hip backward to feel activation of hip flexors and gluteals; add
heel flick to yield circular motion with legs.
Synthesizing
the Theories: Elements of Ideal Biomechanics
Foot
Plant
Heel Striker
Heel Strike benefits include the natural
tendency and actuality for most runners as well as the ability to
achieve greater stride length. The calcaneous as a point of contact
is rounded to accentuate a roll through the foot and toe with most
running shoes structured to toward this stride pattern and can aid
in correcting toward a neutral stance phase (keep you upright in
rolling through to toe-off). The drawbacks to a heel-strike pattern
are more numerous and include the likelihood of striding out too
far in order to make heel contact, the potential to place undue
stress on bones with forces transferred up the anatomical chain,
an increased amount of counterforce and resistance encountered with
heel striking, and the result of utilizing muscles inefficiently
in a pull rather than push fashion for propulsion.
To maximize this pattern a runner may
focus on strengthening the quadriceps muscle to keep the knee in
alignment. Both it and calf complex (Gastrocnemius and Soleus muscles)
should be strengthened including with plyometrics to aid in strong
and even explosive toe-off. Additionally, strong hip flexors will
be required to pull and drive the knee back forward in the recovery
phase of the stride cycle.
Related potential injuries: tibial stress
syndrome, bursitis at knee, spinal compression.
Mid Foot Faller
Benefits to landing toward the midfoot
include the potential to use the smaller muscles and connective
tissues in the foot to disperse shock and store energy for recoil,
the ability to reduce counter-forces and friction if planted as
the forward foot begins its return, fosters improved alignment of
one’s center of mass over the base of support, and fosters
increased cadences and reduced ground contact times. Drawbacks include
the potential for placing more sustained stress on the calf complex
and Achilles tendon as well as arch/fascia if the heel is not factoring
into base of support. This may be exaggerated in those departing
from using a heel-strike pattern through physiological development.
Other potentials are for increased forefoot compression and stress
and decreased stride length.
Runners maximizing this pattern may focus
on maintaining quick lower extremity coordination, a smooth heel
flick aided by the hamstrings, and strong balanced hip extensors
and flexors for a cyclic stride pattern. Massage and dynamic stretching
may be focused on the calf to insure that the Achilles is up to
the challenge of increased downward force placed at the ankle. Time
should be spent in drills or leisure barefoot to insure that the
smaller/intrinsic muscles and ligaments in the foot are able to
accommodate load bearing and responsive to recoil capacities.
Related potential injuries: inflammation
of Achilles tendon or plantar fascia
Forefoot Pounder
Benefits include the potential for a gravity
harnessing forward lean to achieve a forefoot landing, increased
cadence/turn-over with decreased ground contact time, and the potential
to predominately utilize larger hip and lower extremity musculature.
Drawbacks include the potentials for excessive strain on the Achilles
Tendon as well as bony structures up the anatomical chain, excessive
vertical displacement, a reduced capacity to harness plyometric
energy or connective tissue recoil. Probably the least common and
potentially efficient of the three, we’ll leave off with further
review of this pattern.
The Winner Is …
There isn’t one really. Yes, the
secrets out. There are too many factors that dictate the type of
foot plant that is appropriate for one individual versus another.
Additionally, the most efficient runners studied and viewed may
alternate foot plant patterns based on the speed, the event, and
level of fatigue. What is known is that the culmination of several
aspects of form will dictate where and how the foot is planted.
Although nearly all runners are heel strikers
to some extent, a more recent shift in biomechanical evaluation
and training has been toward the promotion of landing toward the
mid foot. The ideal strike zone is on the outside of the foot between
the little toe and heel, allowing the foot to flatten or roll in
slightly in accommodating the load and forming a stable base of
support. In theory this pattern reduces braking forces associated
with heel striking, decreases ground contact time, places the individual’s
weight directly over the base of support, and elicits the strongest
activation of both large muscle groups and the elastic recoil of
connective tissues and tendons.
Those with more flexible feet may land
with a flatter foot and require either increased muscle strengthening
or increased control in a shoe to secure a stable base of support
at foot strike. Those with more rigid feet and less elasticity in
their ligaments and tendons may require increased cushioning or
support of the plantar fascia to avoid trauma and inflammation.
Form should can be broken down into components, but changing one
of those components such as foot strike too quickly and without
addressing the other components that make it possible begs for injury.
Application Opportunities
Barefoot jogging on firmer surface.
Comparing hopping on mid foot to hopping on heels with toes raised.
Use of scooter on flat and uphill.
Knees
It should be the focus of the knees to
lead the motion and pull the foot from the ground, not to push or
pull the body through running. Although all muscles of the legs
must work together for smooth, effort free and/or explosive propulsion,
maximal quadriceps extension translates to increased vertical rise
during toe off. Conversely, an extended knee with quadriceps firing
at first contact will translate to inefficient braking forces. The
quadriceps must stabilize the knee enough for energy to be transferred
through to the springs of the feet and provide the lever with which
to lift and cycle the foot forward.
Posture
Shifting away from the historical upright
views, contemporary theories advocate for adding a slight forward
lean to an erect posture maintained by strong core musculature.
The degree of pelvic tilt is continuous with not only the upper,
but also the lower body for full alignment. Visualize being strapped
to a board running from your ankles to your head. Leaning forward
would require you to flex at the ankles to the point of falling
over, all the while in full body alignment. The further you lean,
the stronger the pull of gravity and the quicker the response time
that would be needed in the legs. Maintaining a slight forward lean
harnesses gravity, minimizes vertical displacement, reduces the
likelihood of striding out and heel striking, and places the lower
body in a better position to push with the gluteals and pull with
the hip flexors. At all points however a straight line should be
found from the ears through the shoulders and hips to the ankles.
Additionally, by focusing the lean at the ankles and not simply
the upper body, you stand a better chance of insuring that your
hips and shoulders efficiently follow in alignment.
Application Opportunities
Jogging with backward, upward, and forward
leans.
Changing speed through altering the degree of forward lean.
Arms
The arms should be held at the sides with
linear movement stemming from the shoulders with the production
of forceful but rhythmic backward driving with the elbows. The wrists
should be straight with fingers cupped but relaxed, with varying
degrees of elbow flexion through the cadence with the hands remaining
above the waist but below the below the shoulders. The hands may
pass slightly in front of the chest but never cross midline. Arm
swing should be the metronome for the legs with a target cadence
of 180 elbow drives per minute.
Application Opportunities
Running with a tortilla or potato chip
in hand.
Use of elastic shoulder/arm bands to promote efficient carriage..
Comparing jogging with straight arms to varying degrees of elbow
flexion.
Sensing the relationship between the direction of arm movement both
laterally and vertically with the legs.
Head and Neck
Avoid excessive movement and keep in alignment.
Most importantly though, keep them relaxed. If you don’t look
like you’re enjoying the task at hand, chances are your body
isn’t appreciating the way you’re doing it.
Stride Mechanics
Working on mid foot landing and insuring
that one’s center of mass is over the base of support at all
times will foster an appropriate stride length. Runners should avoid
over striding as the result is an inefficient and slower heel-strike
pattern. Potentially more beneficial than stride length is the rate
of turn-over or cadence. Immediately after foot strike the runner
should focus on lifting the heel toward the buttocks, driving the
flexed knee forward, not upward. The desirable stride rate is approximately
180 steps or strides per minute. It has been found that as a runner
gets older they become more prone to swinging their foot through
lower to the ground and with longer ground contact time during the
stance or support phase. The result of both is increased inefficiency
and slower running, emphasizing the importance of quick high heel
lifts and quick turnover.
Application Opportunities
Running in place comparing lifting at
heels with lifting at knees.
Striding out with foot strike in front of body and base of support.
Hills
Hills represent greater potential gains
for using proper biomechanics than flats. With downhill running
it becomes even more crucial to assume a slight forward lean with
the center of mass falling in front of the base of support and allowing
gravity to provide the horizontal propulsion. What will take time
is becoming more comfortable with having your foot land behind your
hips and exploring vastly quicker leg turnover. It is not uncommon
to hold back in order to restrain downhill speed. In some cases
it would be dangerous not to. Your lean is your accelerator, but
self-imposed speed limits aren’t always bad things.
With uphill running an athlete should
focus on maintaining a cadence of 180 strikes per minute, but with
a shorter stride length and increased effort at vertical displacement.
With decreased downward forces placed perpendicular to the ground
and through the foot, less plyometric energy is gained or available
for recoil. To compensate the quadriceps, which are not primarily
recruited in running over flat ground, are required to achieve the
forceful knee extension needed for vertical propulsion. Additionally,
the hip flexors will work harder in conjunction with short quick
upward driving movements of the arms for a more forceful vertical
lift.
In
Closing
Your body has paired an anatomical framework
dictated by genetics, with the demands of interests, occupations,
and societal influences placed upon it from birth. In many cases
it has chosen the path of least resistance in wiring neuromuscular
patterns. In some cases you’ve had a hand in forcing it in
directions that it didn’t ask to go. What all the scientists,
coaches, or fitness trend creators in the world cannot prove is
the precise culmination of those influences playing out in your
running biomechanics. Without that, complete perfection can never
be certain and that should not be the goal.
The most critical factor will be learning
to better listen to and understand what your body is telling you.
What will be presented are aspects of “ideal”, and less
than ideal, aspects of form based on current understandings. For
most embodying excellent form, chances are it has come naturally
and through many miles and years, not from the learning of form
theories. For some though theories have been systematically applied
with success, shaved minutes off of times, and led to injury free
running. Success though will require time, patience, and the willingness
to spend time strengthening your body in new ways based upon the
new stresses that will be encountered.
It will take time to retrain the body
and, in effect, redevelop postures, strengths, weakness, and interplays
between muscles, joints and ligaments. In that time intensity of
training should be reduced if not eliminated, and moments taken
away from overanalyzing how you should be running. The goal is to
enjoy running, become a bit more efficient, a little less prone
to injury, and, if possible, a little quicker in the process. While
efficient form ultimately should remain the path of least resistance,
rushing into new territory too quickly will surely lead to frustration
and injury. So enjoy playing with your biomechanics, but ultimately
don’t take the fun and ease out of the running style that
comes naturally to you.
Ian Golden is owner and operator of The
Finger Lakes Running Company.
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