Universität Wien - WS 2004/05
Mechanical and metabolic
Introduction
Specific equipment
energy aspects of different
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Alpine ski-touring binding
binding-boot systems in
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Front part: hinge joint
alpine ski-touring
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Rear part: loose for walking, fixed for skiing
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Hermann Schwameder
Alpine ski-touring boots
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‚loose‘ hinge joint at the ankle
for walking
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‚fixed‘ for skiing
Introduction
Introduction
Different systems on the market
Purposes of the study
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ƒ
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weight and design relevant
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Estimation of mechanical energy demand
for different binding-boot systems (study I)
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Effect of different binding-boot systems on
metabolic energy in alpine ski touring (study II)
recreational ski-touring
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comfort (design)
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safety (design)
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stability (design and weight)
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reduction of fatigue (weight)
competitive ski-touring
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bindings (IIa)
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boots (IIb)
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‘long term’ (IIc)
reduction of fatigue (weight)
Methods – equipment
Methods – mechanical energy (study I)
bindings
boots
Energy for elevation
A
B
1
C
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ƒ
ƒ
ƒ
weight
material
release mechanism
fixation of boots
h
ϕ
ƒ
ƒ
ƒ
ƒ
ƒ
weight
material
stiffness
comfort
design
Epot = m.g.h
2
a
FG
1
Results – mechanical energy (study I)
Results – mechanical energy (study I)
Bindings
ϕ
a
ϕ
1 step (15°):
FG
4
75 J
E [J]
Boots
FG
a
4
1 step (15°):
75 J
E [J]
3
3
76%
1.9 %
84%
2.1 %
2
2
1
1
0.3
6 %%
0.3
6 %%
11%
0.3
%
A
B
C
0
0
A
B
C
Methods – metabolic energy (study II)
Methods – metabolic energy (study II)
Oxygen consumption (study II)
Study IIa: bindings
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Walking on a treadmill
(inclined 15°)
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2.5 km/h
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Oxygen uptake
(Cosmed K4b²)
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ANOVA
(repeated measurements)
VO2
measurements
warm up
change of skis
16 subjects
IIa: ‘bindings’
IIb: ‘boots’
IIc: ‘long term’
20 min warm up
5 min ‚steady state‘
2 changes of skis (randomised)
time
Methods – metabolic energy (study II)
Methods – metabolic energy (study II)
Study IIb: boots
Study IIc: long term
VO2
VO2
measurements
warm up
change of boots
warm up
10 subjects
20 min warm up
5 min ‚steady state‘
1 change of boots (randomised)
time
measurements
measurement
(8 phases á 10 min)
4 subjects
10 min warm up
80 min ‚steady state‘ (8 x 10 min)
A1 vs C2 (1 week, randomised)
time
2
Results – metabolic energy (study II)
Results – metabolic energy (study II)
Study IIa: bindings
Study IIb: boots
40
VO2
[ml/min/kg]
∆ [A C]
2.6 % (p < 0.01)
∆ [B C]
1.9 % (p < 0.01)
∆ [1 2]
38
VO2
[ml/min/kg]
39
36
0.6 % (p > 0.6)
36
34
**
**
33
32
A
B
C
30
1
Results – metabolic energy (study II)
2
Discussion
Bindings
Study IIc: long term
∆ [A1
35
33
ϕ
C2] 4.5 % p < 0.05)
FG
a
VO2
[ml/kg/min]
*
40
*
*
4
high weight
31
low weight
29
E [J]
VO2
[ml/min/kg]
38
3
36
2
34
1
0
**
**
32
A
B
A
C
B
C
27
C2
A1
time [min]
25
5
15
25
35
45
55
65
∆ Emech ≈ ∆ Emetab
75
Discussion
Discussion
Boots
Study IIc: long term
ϕ
4
a
E [J]
FG
35
39
VO2
[ml/min/kg]
3
33
VO2
[ml/kg/min]
high weight
36
2
31
33
1
A
B
C
low weight
29
30
0
1
2
27
C2
A1
25
∆ Emech ≈ ∆ Emetab
5
15
25
35
VO2 increases
time [min] over time
∆ VO2 [A1 C2] increases over time
45
55
65
75
3
Conclusion
ƒ Different binding-boot systems affect the
metabolic energy cost during uphill walking
Relevant aspects to focus on
ƒ Stability
ƒ Saftey (resease mechanism)
ƒ Comfort of handling
ƒ Explained by different mechanical conditions
ƒ Differences additional weight: 20 – 35 N
ƒ Lower energy cost relevant
ƒ Performance (competitive)
ƒ Saving energy for downhill runs (recreational)
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Fixation of the boots
Release of the boots
Adjustment of step elevation
Change to skiing and walking mode
Rolling motion of the foot
ƒ Energy
ƒ Weight, moment of inertia
ƒ Position of the pivot point
ƒ Design
Thank you for your
attention
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