Running Form Modification: When Self-selected is Not Preferred · 2010-05-17 · Running Form Modification: When Self-selected is Not Preferred Bryan Heiderscheit, PT, PhD Department

Running Form Modification:

When Self-selected is Not

Preferred

Bryan Heiderscheit, PT, PhDBryan Heiderscheit, PT, PhDDepartment of Orthopedics and Rehabilitation

Department of Biomedical Engineering

University of Wisconsin-Madison

(C) 2010 Bryan Heiderscheit, PT, PhD

Where is the Knee Pain?

9.4 min/mile pace

172 steps/min 180 steps/min


Outline

� Determinants of step frequency/length

� Biomechanical effects of forced change in step frequencyfrequency

� Evidence for application of step frequency change in treating runners with anterior knee pain


Step Frequency Determinants

External factors:

� Velocity

Optimized for metabolic cost• minimize muscle activity

Internal factors:

� Anthropometry� Velocity

� Grade

� Footwear

� Surface properties

Cavanagh and Kram (1989) Med Sci Sports ExercCavanagh and Williams (1982) Med Sci Sports Exerc

� Anthropometry

� Developmental status

� Muscle fiber composition

� Fatigue

� Injury history


Stride Frequency and O2 Uptake

� Most runners naturally choose a stride length–frequency combination that combination that minimizes metabolic cost

� Accomplished through adjustment of leg stiffness so that optimal muscle activation is achieved

Cavanagh and Williams (1982) Med Sci Sports Exerc


COM Vertical Displacementand Step Frequency

� Increased step frequency:

� Decreased contact timetime

� Decreased COM vertical displacement

� Slight decrease in vertical GRF

Morin et al. (2007) J Biomechanics


COM Vertical Displacement and Step Frequency

� Increased step frequency reduces vertical displacement of COM� r=-0.81

8

10

12

CO

M D

isp

lace

me

nt

(cm

)

Non-trained

Well Trained

Highly Trained

� r=-0.81

� Step frequency appears to increase with training experience� Similar running speed

across subjects

Slawinski et al. (2005) Med Sci Sports Exerc

4

6

8

2.5 2.7 2.9 3.1 3.3 3.5 3.7

CO

M D

isp

lace

me

nt

(cm

)

Step Frequency (Hz)

150 222186

(steps/min)


Step Frequency and Leg Stiffness

� Leg stiffness increases with step frequencyfrequency

� Minimal change if ±10% PSF

Morin et al. (2007) J Biomechanics Farley and Gonzalez (1996) J Biomechanics


Metabolic Cost vs Tissue Stress

Metabolic

� Forcing a shift away from preferred may be necessary under some circumstances

Cavanagh (1987) Foot Ankle

� Injury Recovery and Prevention

� Tissue protection

� Load distribution

Metabolic cost

Local tissue stress/strain


Stride Frequencyand Tibial Accelerations

� Decreased tibialaccelerations with increased stride frequency

� Constant speed� Constant speed

Clarke et al. (1995) J Sports Sci

� More vertical leg posture at initial contact

Farley and Gonzalez (1996) J Biomechanics

-10%

PSF +10%


Location of Injury

5 most common injuries

� Patellofemoral pain syndrome

� Iliotibial band friction Knee

Achilles/Calf6.4%

Other10.8%

� Iliotibial band friction syndrome

� Plantar fasciitis

� Tibial stress fracture

� Knee meniscal injuries

Knee42.1%

Foot/ankle16.9%

Lower Leg12.8%

Hip/Pelvis10.9%

Taunton et al. (2002) Br J Sports Med


Running-related Injuries

1. Decrease horizontal distance of foot-ground contact from COM

� Reduce braking impulse

� Reduce knee extensor moment

Potential benefits of increased step frequency:

� Reduce knee extensor moment

2. Increase lower extremity stiffness

� Reduce vertical excursion of COM

� Increase muscle pre-activation


Step Frequencyand Joint Mechanics

� 50 healthy runners� > 15 miles/week

� Run at self-selected speed� constant across conditions� constant across conditions

� 5 step frequencies:� Preferred (PSF)� PSF ± 5%� PSF ± 10%

� Paced by metronome


Step Frequency Manipulation

Preferred(160 steps/min)

Preferred + 5% (168 steps/min)

Preferred + 10% (176 steps/min)


COM and Forces

1.1

1.2

1.3

% P

SF

0.7

0.8

0.9

1

-10 -5 PSF +5 +10

Step Frequency (% PSF)

% P

SF

COM vertical displacement

COM-heel distance

GRF - braking impulse

GRF - peak vertical


Knee Angleand Moment

1

1.1

1.2

1.3

30

40

50

60

Knee Ext Moment

(%PSF)

Kn

ee

Fle

xio

n A

ng

le (

de

g)

mid-stance

0.7

0.8

0.9

1

0

10

20

30

-10 -5 PSF +5 +10Knee Ext Moment

(%PSF)

Kn

ee

Fle

xio

n A

ng

le (

de

g)

Step Frequency (% PSF)

Knee Flexion - IC

Knee Flexion - Peak

Knee Extension Moment

initial contact


Clinical Application

� Runners with anterior knee pain

� Trial treatment of cadence manipulation

� 5-10% increase in step

PSF (162) with knee pain

172 without knee pain� 5-10% increase in step

frequency using metronome on treadmill

� 1-2 min period of adjustment

� 50+% decrease reported in symptoms during session

� Follow-up indicates immediate symptom improvement/resolution


Utilization of Step Frequency Manipulation

� Temporary form change to maintain mileage� Reduce load to knee joint

� Strategy to promote muscle activation prior to loadingloading� mechanism to facilitate carryover of strength gains into

running

� Consider as more permanent change to running form� “better to understride [length] than overstride”…especially in

beginning runners

Elliott and Blanksby (1979) Br J Sports Med


Step Frequency and Anthropometrics

� Anthropometrics should not be used to determine the appropriateness of a person’s step length/frequency

� Anthropometrics are not strongly associated with step length

� tall or long legged runners do not necessarily have a longer stride length

� runners with thinner legs do not have a longer stride length� runners with thinner legs do not have a longer stride lengthCavanagh and Kram (1989) Med Sci Sports Exerc

� 180 steps/min suggested as optimum for performance

� 145-160 steps/min is common in recreational runners

� Requires trial-and-error approach

� Fast and simple


Evidence for Training Carryover

� Reduce impacts by using impact as feedback

� 8 training sessions over 2wks

� new running form maintained at 4wk maintained at 4wk follow-up with no intermediate training

Crowell and Davis (2006) Proceedings, Am Society Biomechanics


Metabolic Cost of Step Frequency Change

� 8% shift from preferred stride frequency (PSF) increased O2 uptake by 3 ml/kg/min

Hunter et al. (2007) Eur J Appl Physiol

� Moderate deviations in stride length had minimal effects on O2 uptakeCavanagh and Williams (1982) Med Sci Sports Exerc


Other Potential Applications

Increase step frequency:

� Iliotibial band syndrome

� Reduce knee flexion excursion

� Plantar heel pain� Plantar heel pain

� Reduce foot-ground angle at initial contact

� Anterior compartment

� Reduce eccentric demand on tibialis anterior


Comprehensive Treatment

� Step frequency change part of treatment plan

� Additional interventions included as needed to target included as needed to target impairments

� strengthening and stretching


Summary

� Increasing step frequency reduces knee joint loading during running

� Preliminary evidence of symptom reduction by increasing step frequency in runners with increasing step frequency in runners with anterior knee pain

� Running form modification should be considered as an adjunct to current interventions

� injury prevention or recovery


Acknowledgements

� Graduate Students

� Liz Chumanov, PhD� Max Michalski, MS� Kerry Finnegan, BS� Christa Wille� Christa Wille

� APTA

� Sports Physical Therapy Section� Private Practice Section� Orthopaedic Section


Thank You

University of Wisconsin, Madison, WI


References1. Cavanagh, P.R., and R. Kram. Stride length in distance running: velocity, body dimensions, and added

mass effects. Med.Sci.Sports Exerc. 21:467, 1989.

2. Cavanagh, P.R., and K.R. Williams. The effect of stride length variation on oxygen uptake during distance running. Med Sci Sports Exerc. 14:30-35, 1982.

3. Morin, J.B., P. Samozino, K. Zameziati, and A. Belli. Effects of altered stride frequency and contact time on leg-spring behavior in human running. J Biomech. 40:3341-3348, 2007.

4. Slawinski, J.S., and V.L. Billat. Difference in mechanical and energy cost between highly, well, and nontrained runners. Med Sci Sports Exerc. 36:1440-1446, 2004.

5. Farley, C.T., and O. Gonzalez. Leg stiffness and stride frequency in human running. J.Biomech. 5. Farley, C.T., and O. Gonzalez. Leg stiffness and stride frequency in human running. J.Biomech. 29:181, 1996.

6. Cavanagh, P.R. The biomechanics of lower extremity action in distance running. Foot Ankle. 7:197, 1987.

7. Clarke, T.E., L.B. Cooper, C.L. Hamill, and D.E. Clark. The effect of varied stride rate upon shank deceleration in running. J Sports Sci. 3:41-49, 1985.

8. Taunton, J.E., M.B. Ryan, D.B. Clement, D.C. McKenzie, D.R. Lloyd-Smith, and B.D. Zumbo. A retrospective case-control analysis of 2002 running injuries. Br J Sports Med. 36:95-101, 2002.

9. Elliott, B.C., and B.A. Blanksby. Optimal stride length considerations for male and female recreational runners. Br J Sports Med. 13:15-18, 1979.

10. Hunter, I., and G.A. Smith. Preferred and optimal stride frequency, stiffness and economy: changes with fatigue during a 1-h high-intensity run. Eur.J.Appl.Physiol. 100:653, 2007.

11. Crowell, H.P., and I. Davis. Reducing lower extremity loads through gait retraining using real-time feedback methods. In Proceedings of the Am Society Biomechanics. Blacksburg, VA, 2006.


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Running Form Modification: When Self-selected is Not Preferred · 2010-05-17 · Running Form Modification: When Self-selected is Not Preferred Bryan Heiderscheit, PT, PhD Department