does changing footfall patterns benefit runners?€¦ · joseph hamill, phd . professor,...
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Biomechanics Laboratory
Joseph Hamill, PhD Professor, Kinesiology
Associate Dean for Research, SPHHS
Biomechanics Laboratory
University of Massachusetts Amherst, MA 01003
Does Changing Footfall Patterns Benefit Runners?
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Footfall Patterns - RF
2
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Footfall Patterns - FF
3
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Footfall Patterns - MF
4
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Rearfoot v. Forefoot Runners
• of 753 runners at the 10 and 20 km point of marathon races, 81% RF, 19% MF, 0% FF
• 283 elite runners analyzed at 9.3 mile mark of a half marathon: 75% RF, 24% MF, 1 %FF
• 936 runners analyzed at 10 km point of marathon: 89% RF, 3% MF, 2% FF, 6% asymetrical
Ker et al., (1983)
Hasegawa et al., (2007)
Larsen et al., (2011)
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Why are there so few forefoot runners?
• ancient homo (∼500,000 years ago) may have been a runner (Liebermann et al., 2010)
• what footfall pattern did they use when running?
• Liebermann and others suggest that they used a FF pattern
• argument for using a FF pattern suggests that since ancient homo ran with a FF pattern so........
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• forward dynamics computer model two-dimensional (sagittal) 11 segments: trunk, two legs vertical trunk force ≈ arm swing soft constrains on joint ROM (ligaments, etc.) foot-ground contact wobbling masses (trunk, thighs, calfs)
Miller & Hamill, (2012)
• 12 Hill-based muscle models per leg contractile and series elastic components parameters: dynamometer experiments
Why do we have multiple footfall patterns? Why are there so few FF runners?
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• RF strike pattern for minimal energy solution
• MF strike increased energy rate (15.9 → 16.9 W•kg-1,
+1.2 kcal•min-1)
• FF strike to maximize average speed
Energetic Optimality for Computer Model
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Rearfoot v. Forefoot
• there is little to no evidence that FF or MF running is a healthy alternative to RF running
• there is also little scientific evidence that RF is a healthy alternative to FF or MF running
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear
is metabolically more efficient
decreases the impact forces in running
reduces running-related injuries
What those who advocate change really say?
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear
is metabolically more efficient
decreases the impact forces in running
reduces running-related injuries
What those who advocate change really say?
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Are footwear the cause of few FF runners?
• one argument often mentioned is „modern footwear“
• the development of the modern running shoe (i.e. thick heel) allowed individuals to run with an RF pattern
• the thick heel cushioning thus decreased the number of runners who ran with a FF pattern
1971 2012 2013
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University of Oregon 1977
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear
is metabolically more efficient
decreases the impact forces in running
reduces running-related injuries
What those who advocate change really say?
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• running with a FF pattern is not more economical than running with an RF pattern
Running Economy
0
2
4
6
8
10
12
14
16
18
RF Pattern FF Pattern
NM
R (W
/kg)
11.95 ± 0.68
12.42 ± 0.66
Gruber et al., 2012 Habitual RF Runners
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Speed Group CHO (g·hr-1) CHO (% of EE)
Slow RF 88.89 ± 23.41 51.3 ± 12.7
FF 100.23 ± 21.76 58.5 ± 8.3
Medium RF 131.17 ± 39.65 64.7 ± 15.5
FF 140.08 ± 33.00 71.3 ± 11.4
Fast RF 187.87 ± 58.05 77.9 ± 16.8
FF 186.12 ± 39.82 80.9 ± 11.8
Carbohydrate Oxidation
Gruber et al., 2012
Habitual RF Runners
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear
is metabolically more efficient
decreases the impact forces in running
reduces running-related injuries
What those who advocate change really say?
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Lieberman et al., 2010
RF v. FF Running
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Vertical Ground Reaction Force Component
RF FF
0 20 40 60 80 100 0
500
1000
1500
2000
Percent Support
VG
RF
Com
pone
nt (N
)
Gruber et al., 2011
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-400
0
400
800
1200
1600
0 50 100 150 200 250 Time (ms)
Forc
e (N
)
passive
VGRF
active
2000
Spectral Decomposition of VGF Component
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0
200
300
400
500
600
Am
plitu
de
100
0 0 5 10 15 20 25
Frequency (Hz)
Vertical Ground Reaction Force Frequencies
21
impact peak
active peak
4 – 8 Hz
10 – 20 Hz
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Frequency Content of VGRF
0 5 10 15 20 25 30 0
500
1000
1500
2000
2500
Frequency (Hz)
Am
plitu
de
RF
FF
R
Gruber et al., 2011
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Why is their no impact peak in FF running?
• in RF running, the foot/ground collision occurs early in the support period
• in FF running, the collision occurs later in the support period
RF FF
Percent Support
VG
RF
Com
pone
nt (N
)
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Wavelet Analysis of VGRF Component Rearfoot Pattern Forefoot Pattern
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Time (ms) Time (ms)
Forc
e (N
)
Forc
e (N
)
active peak
impact peak
Bobbert et al., 1992
The Impact Peak in RF running?
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The Impact Peak in FF running?
0
500
1000
1500
2000
0 50 100 150 200
Forc
e (N
)
Time (ms)
Forc
e (N
)
0
500
1000
1500
2000
0 50 100 150 200 Time (ms)
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Do Impacts Cause Injury?
• running on hard surfaces did not increase injuries over running on soft surfaces
• incidence of osteoarthritis found in equal
frequency in runners and non-runners
Van Mechelen, 1992
Lane et al., 1986; Panush et al., 1986; Eichner, 1989
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Injury and Impacts?
• subjects with greater impact peaks had significantly fewer running-related injuries
Nigg, 1997
Relative Injury Frequency (%)
30
20
10
0
Maximum Impact Force (N) Low 25% Medium 50% High 25%
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Do Impacts Really Cause Injury?
?????????
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear
is metabolically more efficient
decreases the impact forces in running
reduces running-related injuries
What those who advocate change really say?
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Injury Epidemiological Studies
• prospective study on 471 runners - no difference in injury rates between FF and RF - suggested injury site affected by portion of the foot that makes initial contact Kleindienst, 2003
• prospective study on 1203 runners - no differences in injury rates between FF and RF - difference in location and kind of injury
Walther, 2005
• few epidemiological studies
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Possible Injuries If Changing to an FF Pattern
• Achilles tendinitis
• Plantar Fasciitis
• Patellofemoral Pain
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Achilles Tendinitis
Gruber et al., 2011
Ach
illes
Tend
on F
orce
(N)
Percent Support
RF
FF
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Plantar Fasciitis
Gruber et al., 2010
RF Segment
FF Segment
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Foot Motion with Different Running Patterns
foot acts like a rigid structure thus plantar fascia is always under tension
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Patellofemoral Pain
Kleindienst et al., 2005
• increased knee abduction and external rotation moments related to PFPS (Stefanyshyn et al., 2001)
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• changing to a FF or MF footfall pattern from an RF pattern:
caused by modern footwear NO
is metabolically more efficient NO
decreases the impact forces in running NO
reduces running-related injuries NO (and possibly causes running-related injuries)
What those who advocate change really say?
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Conclusions
• the change in footfall pattern (i.e. rearfoot to forefoot) may result in stressing tissue not used in the RF pattern possibly resulting in a running-related injury
• our research suggests that changing one’s footfall pattern is not beneficial to the runner
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Take-home Message
Changing one’s footfall pattern is not good!
thus
Variety of one’s footfall pattern is not always the spice of life!
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Thank you!
Questions?
www.umass.edu/biomechanics/