Biomehaniks of Running

8/9/2019 Biomehaniks of Running

1/6

Biomechanics

of Running

Adam Bird

Outline

The running cycle

Spatial parameters

Runners varus?

Impact forces

Incidence of overuseinjuries & risk factors for

runners Do running shoes cause

injury?

Orthoses and running

Summary

References

Assorted articles mentioned

Nigg BM (1986) Biomechanics of runningHumanKinetics Publishers, Illinois, Chapter 1

*Cavanagh PR (1989) The biomechanics of runningand runnning shoe problems. In: Segesser B,Pforringer W (eds). The shoe in sport. YearbookMedical Publishers, p 3-15

*Novachek TF (1998) The biomechanics of running

(review paper) Gait & Posture 7: 77-95 CD-ROM Running & Sprinting: a dynamic analysis

BUND AV 612.76

The running cycle

no double support phase

three phases

stance (40%)

float (30%)

swing (30%)

stance consists of

contact, midstance, propulsion

float phase

body airborne, no foot contact

consists of forward swing and foot descent

The running cycle

the duration of each phase is relative tothe speed of running

jogging: stance > swing

distance: stance = swing

sprinting: stance < swing

Running gait cycle

From: Subotnick SI. Podiatric Sports Medicine. Futura, New York, 1975


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Spatial parameters

step and stride length muchgreater than walking

stride width much narrower

no double support phase

uphill running

shorter stride length

increased stride rate

downhill running

longer stride length

decreased stride rate

Spatial parameters

RUNNINGWALKING

Spatial parameters

at any given running speed, each individualhas an optimal combination of stride lengthand rate to minimise energy requirements

increased speed leads to

increased hip flexion

increased knee flexion

increased forward trunk lean increased float phase duration

decreased support phase

Running style variations

80% distancerunners are rearfootstrikers (Kerr et al, 1983)

Elite sprinters haveonly forefoot contact

Runners varus

foot must be placed under CoG,due to lack of double support

requires adduction of femur in theacetabulum

increased varus position at heelstrike

this varus position may favourincreased STJ pronation,particularly in females

Impact force

F=MV, therefore running will resultin greater impact force than walking

two peaks:

heel strike (2 X BW)

midstance (3 X BW)

joint compressive forces in the foot

may reach up to 10 X BW

high potential for stress fracture

rapid STJ pronation and knee

flexion


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I m p a c t f o r c e

Passive forcePeak - shock ofcontact with theground

Due to active

Muscle forces -Marks end ofDeceleration &Beginning of

acceleration

Impact force

Theres noevidence thatbiomechanicalresearch in load

analysis hascontributed to adecreasedfrequency ofrunning injuries(Nigg, 1990)

Overuse injuries

massive increase in number of joggers in last 25years

estimated thirty million joggers in the USA (Nigg, 1986)

Between 25-50% of runners will sustain an injury that

is severe enough to cause a change in practice orperformance (Renstrom, 1993)

the knee is most common site of injury

Incidence of running injuries

From: Nigg BM. (ed.) Biomechanics of running shoes. Human

Kinetics Publishers, Illinois1986.

KNEE 30%

TIBIA 15%

OTHER 35%

ACHILLES 10%

MLA 10%

Incidence of marathonrunning injuries

Ultramarathon injuries Westfield Syd-Melb, 1990

Knee (31.3%), ankle (28.1%)

Most common Retropatella pain

Achilles tendonopathy

Medial tibial stress syndrome

(Fallon, 1996)

Risk factors: 1st time participation, illness less than 2weeks before, current use of medication, drinkingalcohol once a month or more

(Satterwaite et al, 1999)

Clinical / Historical Factors

associated with overuse injuries* impact force

hard surfaces

stress fractures

downhill running

shin splints, patellartendonopathy

lack of flexibility

esp. achilles and hamstrings

overstriding

hamstrings, knee pain

Shoes (last, stability, age to replace)

running on one side of road environmental LLD


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Aetiological factors that arestrongly associated with injury

Previous injury

Lack of running experience

Running to compete

Excessive weekly running distance

(van Mechelen, 1992)

Aetiological factors that are unclearas to whether associated with injury

Body height

Muscular imbalance

Restricted range of motion

Stability of running pattern

Running on one side of the road Biomechanical malalignment

Warm up/stretching exercises

Shoes/orthoses...(van Mechelen, 1992)

Aetiological factors that are stronglynot associated with injury

Age

Gender

Body mass index

Participation in other sports

Time of year/time of day

(van Mechelen, 1992)

Do running shoes cause injury ?

Evidence:

large increase in overuse injuries over the last 20

years

a Boston marathon study found that there was a

higher incidence of overuse injury in subjects

who wore more expensive shoes

very low incidence of injury in barefoot runners

Do running shoescause injury?

Robbins-Gouw hypothesis:

running shoes cause injury due to

creating a perceptual illusion oflower impact force

excessive cushioning decreases

proprioceptive feedback

body unable to judge severity of

impact

reduced innate impact moderating

behaviour

increased impact(Robbins & Gouw, 1991)


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Shoe factor associated withoveruse injuries?

A large lateral flare provides ground reaction forceswith a longer lever arm for pronating the STJ. Thiswill increase the velocity of contact phase pronationand may predispose to injury (Nigg & Morlock, 1987)

Use of orthoses with runninginjuries

At least 70% of runners who experiencelower extremity symptoms

eg. knee pain, plantar fasciitis, shin pain,iliotibial band tendinitis

report marked improvement withorthotic use

(DAmbrosia, 1985, Donatelli et al., 1988,

Gross et al., 1991, James et al., 1990)

Early 2D studies looking at effectsof orthoses when running

Reduction in

maximum pronation/calc eversion (Clarke,1984)

Maximum pronation velocity (Novic, 1990)

Time-to-max pronation (Bates, 1979)

Total rearfoot motion (Novick, 1990)

Differences in footwear, orthoses, test surfaces, only2D analysis?

Foot orthotics effect on 3D kinematicsof lower limb during running

20 recreational runners

Semi-rigid foot orthoses

Significant change in:

Decreased amount (2) of internal tibialrotation (in first half of stance)

No change in frontal plane rotations (ie.calc inv/ev)

(Nawoczenski, Cook & Saltzman, 1995)

General principles for runningorthoses

Semi-flexible?

Aware of greater forces being placedthrough devices - discomfort/fracture?

Rearfoot posting?

Competitive athletes = weight ofdevices?

Long term sequelae ofrunning?

Knee Osteoarthritis?

117 former athletes, now 45-68 years old

No

(Factors that do: previous knee injuries,High BMI at age 20, participation in heavywork, kneeling/squatting work, previouslyplayed soccer/heavy weightlifting)

(Kujala et al, 1995)


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Summary

significantly altered mechanics due to:

floatation phase

impact forces up to 3 X BW

rapid contact phase pronation

increased varus heel strike

not necessarily heel to toe pattern

increased incidence of injury

Know risk factors

different orthotic requirements

Importance of early recognition of

symptoms of overuse & complete rehabilitation

Case Study lecture

Please read (Keenan, 1997) in yourPOD21PBM manual

Summarises some of the issues Craigspoke about in his lectures so far this year

Talks about integration of traditional andnewer theories of foot function

Documents

Biomehaniks of Running