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3/1/2009
UW Musculoskeletal Biomechanics
Research
Why It’s Hard to Find
a Good Saddle
Musculoskeletal
Imaging
Heidi Ploeg, Ph.D., Assistant Professor
Darryl Thelen, Ph.D., Associate Professor
Motion
Analysis
Departments of Mechanical Engineering and
Biomedical Engineering
University of Wisconsin-Madison
Modeling &
Simulation
Acknowledgements:
Jackson Potter, Julie Sauer, Christine Weisshaar, UW-Madison
Matt Prest, Damon Rinard
Trek Bicycle Corp.
UW Musculoskeletal
Biomechanics
Lab
UW Musculoskeletal
Biomechanics
Lab
Research Questions
Terminology – Hip and Pelvis
posterior
back
posterior
back
During seated cycling:
1. What is the orientation and motion of the
pelvis?
anterior
anterior
front
front
2. What is the pressure distribution on the
saddle?
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Terminology – Directional Terms
Anterior
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Pelvic Tilt
Bressel and Larson, Med Sci Sports Exerc 2003
Toward front of body
Posterior
Posterior
posterior
Toward back of body
Anterior
anterior
P
20 female cyclists
Standard, cutout & noseless saddles
Anterior pelvic tilt of 16° on the tops
Increases to 29° in the drops
Slightly greater tilt on cutout and noseless
saddles
Only static measures
A
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
1
3/1/2009
Pelvic and Hip Motion
Pressure Measurement
Neptune and Hull, J Biomech 1995
Lowe et al., Med Sci Sports Exerc 2004
Intra-cortical bone pins
32 males, 1 female (police officers)
70 rpm and 150 W on 4 different saddle
designs
Recommended noseless saddles for >2x
lower average pressures in perineum
No increase in shoe or handlebar pressure
Upright, recreational-style cycling
Did not vary power, cadence or gender
Hip translated forward and down (~10 mm)
during down stroke
Hip moved much less than greater
trochanter marker
Movement facilitates power transfer from
upper to lower body
Only one subject – a 45 yr old competitive
cycist
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Bressel et al., J Biomech 2006
Males (5)
Custom apparatus loaded
perineum with a bicycle saddle
Measured pressure
distributions
Urethra and cavernosa artery
are compressed
Locations of maximum
compression and maximum
pressure align
Literature
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Factors that Can Influence Pelvic
Motion and Saddle Pressure
MRI Study
Terminology
Terminology
Methods
pubic
symphysis
Hand position
Power output
Bicycle setup
Flexibility
Pelvic anthropometry
Saddle geometry
Saddle stiffness
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Experiment and Protocol
Terminology
Literature
females
Methods
males
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Pelvic Motion Measurement
Experienced cyclists:
12 Males
14 Females
Bike fit to subjects
170 mm cranks
145 mm drop handlebars
Protocol:
Powers: 100, 150, 200 W
Hand positions: tops & drops
Cadence: 90 rpm
Pelvic motion tracked
using 3 markers placed
on posterior
anatomical landmarks:
Right and left PSIS
Sacral marker
Measures:
3D full body kinematics
Saddle pressure
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
2
3/1/2009
Dynamic Pressure Measurement
Flexibility Measurements
90 sensors,
100 Hz,
18.75x18.75 mm2
over the whole
saddle, Bicycle
Pressure mat
(Novel, Inc.)
Lumbar Flexibility
Hamstring Flexibility
Gajdosik et al.
Tousignant et al.,
Physical Therapy 1992
Disability and Rehabilitation 2005
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Methods
Results
Males
Females
Hip joint center
width (mm)
198.8 (12.5)
192.9 (9.4)
Ischial tuberosity
width (mm)
116.5 (16.0)
134.9 (9.2)*
Hamstring
flexibility (deg)
31.7 (11.8)
27.2 (6.5)
Lumbar flexibility
(mm)
21.2 (1.0)
UW Musculoskeletal
Biomechanics
Lab
20.6 (1.0)
Determined spherical hip joint
center of rotation in pelvis
Measured distance between
impressions on floral foam
Summary
Hip Joint Center
Ischial Tuberosity Width
Literature
Literature
Results:
Anthropometry and Flexibility
Anthropometry Measurements
Terminology
Terminology
Methods
Results
Summary
*p<0.05
UW Musculoskeletal
Biomechanics
Lab
Males
Females
198.8 (12.5)
192.9 (9.4)
Ischial tuberosity
width (mm)
116.5 (16.0)
134.9 (9.2)*
Hamstring
flexibility (deg)
31.7 (11.8)
27.2 (6.5)
Lumbar flexibility
(mm)
21.2 (1.0)
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Research Questions
Anthropometry and Flexibility
Hip joint center
width (mm)
Terminology
♀
During seated cycling:
♂
2. What is the pressure distribution on the
saddle?
1. What is the orientation and motion of the
pelvis?
20.6 (1.0)
*p<0.05
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
3
3/1/2009
Pelvic Motion and Dynamic Saddle
Pressure During Cycling
Research Questions
During seated cycling:
1. What is the orientation and motion of the
pelvis?
2. What is the pressure distribution on the
saddle?
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Hip Translations and
Pelvic Rotations
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Hip Vertical Translation
Axial rotation
Hip
Forward tilt
Vertical
Greater
Trochanter
Lateral roll
Fore-Aft
Neptune and Hull 1995
Hip translates downward during last 75% of the down-stroke
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Hip Fore-Aft Translation
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Lateral Pelvic Roll
Hip
Greater
Trochanter
Neptune and Hull 1995
Hip translates forward during last 75% of the down-stroke
Similar pattern in males & females and in tops & drops
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Roll ~2° toward side of down-stroke
Similar in males and females, tops and drops
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
4
3/1/2009
Forward Pelvic Tilt
Axial Rotation
♀
♀
♂
~3° inward rotation on side of down-stroke
Slightly larger among females at the higher power outputs
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Average Forward Pelvic Tilt
Pelvic tilt oscillates twice with each pedal stroke
Peak forward tilt at top and bottom dead center
Terminology
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Drops
Less
Forward
Tilt
♂
Terminology
Literature
Forward Pelvic Tilt: Males
Females
exhibited
significantly
greater forward
tilt in drops
Note location of
the ischial
tuberosities
♀
♂
More lumbar flexibilty
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Research Questions
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Dynamic Saddle Pressure
Center of
Pressure moved
fore and aft
-3 to +3 mm
Peaked
twice/cycle
0° and 175°
During seated cycling:
1. What is the orientation and motion of the
pelvis?
2. What is the pressure distribution on the
saddle?
kPa
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
5
3/1/2009
Posterior Pressure / Body Weight:
Effect of Power and Hand Position
Dropped with increasing
power
Dropped when hands were
moved from the tops to
the drops
Posterior Pressure / Body Weight:
Effect of Hand Position
Dropped when hands
were moved from
the tops to the
drops
Center of pressure
moved forward with
hands in the drops.
Tops
Drops
tops
Terminology
Literature
Methods
Results
Summary
drops
UW Musculoskeletal
Biomechanics
Lab
Anterior Pressure / Body Weight:
Males
UW Musculoskeletal
Biomechanics
Lab
Anterior Pressure / Body Weight:
Females
No change with power or
hand position
tops
Terminology
Literature
Methods
Results
Summary
tops
drops
UW Musculoskeletal
Biomechanics
Lab
Anterior Pressure / Body Weight:
Effect of Hand Position - Females
Tops
No change with power
Increased when hands
were moved from the
tops to the drops
Terminology
Literature
Methods
Results
Summary
drops
UW Musculoskeletal
Biomechanics
Lab
Posterior Center of Pressure:
Width
Increased with sitbone
width, slope=0.7
Not sitting on sitbones
Increased when
hands were moved
from the tops to
the drops
Drops
UW Musculoskeletal
Biomechanics
Lab
♂
♀
UW Musculoskeletal
Biomechanics
Lab
6
3/1/2009
Posterior Center of Pressure:
Location
Pop Quiz!
Who is this cyclist?
Moved forward with
narrower sitbones
♀
♂
UW Musculoskeletal
Biomechanics
Lab
Summary – Gender Differences
UW Musculoskeletal
Biomechanics
Lab
Discussion – Male Pelvis in Drops
Pelvic bone structure
Females greater ischial tuberosity width
Females more rounded pubic arch
♂
♀
20 deg
120 mm
70
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Discussion – Female Pelvis in Drops
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
140
What is the orientation and
motion of the pelvis?
In the drops hand position, forward
pelvic tilt was greater in females, and
males with low lumbar flexibility
Pelvic motion arises naturally during
pedaling, with the largest rotations
occurring out of the sagittal plane
Pelvic motion may facilitate power
transfer between limbs, and between
upper and lower body
24 deg
130 mm
80
Terminology
Literature
Methods
Results
Summary
130
UW Musculoskeletal
Biomechanics
Lab
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
7
3/1/2009
How Might Pelvic Motion Facilitate
Power Transfer?
Pelvic motion means::
Hip joint reaction can
transfer power
Note: Forward and
downward motion of
the hip coincides with
the large hip reactions
during the downstroke
What is the pressure
distribution on the saddle?
Center of pressure
Moves back and forth twice per cycle
Moves forward with hands in the drops
Posterior peak pressure / body weight
Drops with increasing power output
Drops with hands in the drops
tops
drops
Anterior peak pressure / body weight
Power=Force••Velocity
Terminology
Literature
Methods
Results
Summary
Males: doesn’t change with power or hand position
Females: doesn’t change with power BUT increases with
hands in the drops
Terminology
What is the pressure distribution on
the saddle?
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
What to think about when
choosing a saddle
For both genders:
Pelvic motion arises naturally and
may facilitate power transfer
Where you sit on the saddle is
related to your sitbone width
Posterior peak pressure / body
weight was highest and furthest
back with hands on the tops
For females only:
Anterior peak pressure
increased with hands in the
drops
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Why is it hard to find a good
saddle?
Terminology
Literature
Methods
Results
Summary
UW Musculoskeletal
Biomechanics
Lab
Special Thanks
Trek Bicycle Corp for funding this project
Matt Prest and Damon Rinard for technical support
BME Student Researchers
James Potter
Julie Sauer
Christine Weisshaar
PT Students
Ed Immekus
Liz Sierra
Ian Metzgen-Ohlswager
Autumn King
Subjects
UW Musculoskeletal
Biomechanics
Lab
UW Musculoskeletal
Biomechanics
Lab
8
3/1/2009
Thank You!
Questions?
Physical Characteristics of Saddle
Jackson Potter
UW Musculoskeletal
Biomechanics
Lab
UW Musculoskeletal
Biomechanics
Lab
Methods:
Methods:
Physical Characteristics of Saddle
Saddle Compliance
Basic Measurements
Compliance Testing
Surface Geometry
Structural compliance
Cushion compliance
Length, width, height, weight, etc.
Cushioning and base/shell
Laser scan saddles
Slope of cross-sections in perineum and rear
Topographical maps of surface
UW Musculoskeletal
Biomechanics
Lab
UW Musculoskeletal
Biomechanics
Lab
Results:
Results:
Saddle Compliance
Saddle Compliance
Total Midpoint Compliance
Deflection vs. Load Curves
0.7
Less Stiff
300
More Stiff
0.6
250
7.04x – 8.5
0.4
Cushion Compliance
Base Compliance
0.3
0.2
Deflection of
Cushioning
15
20
25
Load (lb)
30
35
45
Fi'zi:k Arione
UW Musculoskeletal
Biomechanics
40
Lab
Selle Italia SLR
10
Bontrager Race X
Lite Womens
5
Selle San Marco
Regal
0
Selle Italia Flite
0
0
Bontrager Race X
Lite Mens
Deflection of
Base
Bontrager Race X
Lite Pro
2.98x – 9.5
Fi'zi:k Vitesse
y=
Selle San Marco Era
Lux
50
Performance E3
0.1
Total
Deflection
Selle Italia Prolink
100
Bontrager Race Lite
Mens
Deflection (in/1000)
150
Compliance (mm/kg)
0.5
y=
200
UW Musculoskeletal
Biomechanics
Lab
9
3/1/2009
Methods:
Results:
Laser Scanning
Laser Scanning
Ge ome tric Curve s 20% from Re ar Edge
Geometric Curves 20% from Rear Edge
10
10
Saddle
Most Curved
-45
-40
-35
-30
-25
-20
-15
-10
Vertical Position (mm)
Vertical Position (mm)
5
-45
Fizik Arione
5
5
Experimental High Curvature
-40
-35
-30
-25
-20
-15
0
Selle
Italia
Flite
-5
0
5
10
-10
15
20
25
5
30
35
40
-5
0
5
10
15
-5
Intermediate
25
30
35
40
2
45
1511
Fizik Aliante
2625
21
E1
Race X Lite Womens
Curvature
Analysis
Selle Italia Prolink
UW Musculoskeletal
Biomechanics
Lab
7
2
Transverse Position (mm)
Race Lite Womens
Surface Maps
4
3
-15
Race X Lite Pro
Experimental Low Stiffness
-15
E4E1
Selle -10San Marco Strada
Race-20X Lite Mens
-10
10
26
Experimental Med Curvature
20
E5
E512
E4
123
-5
0
45
1015
Selle Italia SLR
4
11
25
21
7
Terry Butterfly
Least Curved
-20
Transverse Position (mm)
Fizik Vitesse
UW Musculoskeletal
Biomechanics
Lab
UW Musculoskeletal
Biomechanics
Lab
10