Biomechanics for Rowing Technique and Rigging · Velocities Rigging Handle/Gate Force Boat Velocity...
Transcript of Biomechanics for Rowing Technique and Rigging · Velocities Rigging Handle/Gate Force Boat Velocity...
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11
Biomechanics for Rowing Technique and Rigging
Dr. Valery KleshnevDr. Valery Kleshnev
Rowing Science ConsultantRowing Science Consultant
President, BioRow Ltd.President, BioRow Ltd.
www.BioRow.comwww.BioRow.com
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22
ContentsContents
�� Model of rowing efficiency;Model of rowing efficiency;
�� The main principles of effective rowing technique;The main principles of effective rowing technique;
�� Biomechanical basics of rigging;Biomechanical basics of rigging;
�� Biomechanical measurements and tools;Biomechanical measurements and tools;
�� Biomechanical feedback;Biomechanical feedback;
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Efficiency and effectiveness of techniqueEfficiency and effectiveness of technique
Result
Metabolic Power
(Physiology)
Technique
(Biomechanics)
Psychology Race Strategy
EfficiencyEffectiveness
Rowing Style /
Rower’s Efficiency
Blade
Efficiency
Force
Curve
Boat
EfficiencyRowing
Power
Segments’
Velocities RiggingHandle/Gate
Force
Boat Velocity
& Acceleration
Horizontal Oar
Angles
Performance Level
Analysis Level
Measurement Level
Vertical Oar
Angle
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How we define rowing technique efficiency?How we define rowing technique efficiency?
The three main parts of rowing as a process of The three main parts of rowing as a process of
energy transformationenergy transformation
Propulsive PowerBlade Propulsive Efficiency
Was
tePow
er
Minimal required Power
Boat Velocity Efficiency
ConsumedPower
Handle Power
Internal (muscle)
Efficiency
Waste
Heat Energ
y
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Amounts and Losses of energy during rowing Amounts and Losses of energy during rowing
(example values)(example values)
1667
Total energyTotal energy
consumingconsuming
400
Handle PowerHandle Power
328
PropulsivePropulsive
PowerPower
310
MinimalMinimal
Required PowerRequired Power
93.4%
5.3% 1.3%
Internal LossesBlade Shift Losses
Velocity Fluctuation Losses
0
400
800
1200
1600
2000
Power (W)
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Rowing StylesRowing Styles
�� RosenbergRosenberg -- Large, forward Large, forward
declination of the trunk at the declination of the trunk at the
beginning of the stroke, then beginning of the stroke, then
strong leg extension without strong leg extension without
significant trunk activation;significant trunk activation;
�� AdamAdam -- Comparatively long legs Comparatively long legs
drive and limited amplitude of the drive and limited amplitude of the
trunk. Simultaneous activity of trunk. Simultaneous activity of
legs and trunk during the stroke;legs and trunk during the stroke;
�� DDRDDR -- Large, forward declination Large, forward declination
of the trunk, which begins the of the trunk, which begins the
drive, followed by simultaneous drive, followed by simultaneous
activity of the legs;activity of the legs;
�� IvanovIvanov -- consequent timing and consequent timing and
emphasis on the legs drive.emphasis on the legs drive.
Adam style
DDR style Rosenberg style
Ivanov style
Legs Emphasis
Simultaneous Timing Consequent Timing
Trunk Emphasis
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Rosenberg StyleRosenberg Style
0
500
1000
1500
2000
2500
3000
Total
Legs
Trunk
Arms
Rosenberg style
Angle
Pow er (W)
Large, forward declination Large, forward declination
of the trunk at the of the trunk at the
beginning of the stroke, beginning of the stroke,
then strong leg extension then strong leg extension
without significant trunk without significant trunk
activationactivation
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DDR styleDDR style
0
500
1000
1500
2000
2500
3000
Total
Legs
Trunk
Arms
DDR style
Angle
Pow er (W) Large, forward declination of the Large, forward declination of the
trunk, which begins the drive, trunk, which begins the drive,
followed by simultaneous followed by simultaneous
activity of the legsactivity of the legs
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Adam StyleAdam Style
Comparatively long legs Comparatively long legs
drive and limited drive and limited
amplitude of the trunk. amplitude of the trunk.
Simultaneous activity of Simultaneous activity of
legs and trunk during legs and trunk during
the strokethe stroke
0
500
1000
1500
2000
2500
3000
Total
LegsTrunk
Arms
Adam style
Угол
Power (W)
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Ivanov StyleIvanov Style
Consequent timing and Consequent timing and
emphasis on the legs driveemphasis on the legs drive
0
500
1000
1500
2000
2500
3000
TotalLegsTrunkArms
Ivanov style
Angle
Power (W)
The main principles of effective techniqueThe main principles of effective technique
1.1. Catch through the stretcher;Catch through the stretcher;
2.2. Using the most powerful muscle groups first;Using the most powerful muscle groups first;
3.3. Optimisation of the velocity of the muscles Optimisation of the velocity of the muscles
contraction;contraction;
4.4. Strong posture: efficient back curve;Strong posture: efficient back curve;
5.5. Emphasis of the force application at the front, Emphasis of the force application at the front,
““frontfront--loadedloaded”” drive, the earlier, the better;drive, the earlier, the better;
6.6. Coordinated and fast switching of the musclesCoordinated and fast switching of the muscles--
antagonists;antagonists;
7.7. Effective acceleration of the centre of mass of Effective acceleration of the centre of mass of
the rower;the rower;
8.8. Efficient finish of the drive through the handle.Efficient finish of the drive through the handle.www.biorow.comwww.biorow.com
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The main principle of effective CATCHThe main principle of effective CATCH
�� ««Catch through the Catch through the
stretcherstretcher»» givesgives 46% 46%
higher velocity of the higher velocity of the
blade at the same handle blade at the same handle
velocity;velocity;
�� ««Catch through the Catch through the
stretcherstretcher»» is preferable is preferable
because of using of more because of using of more
powerful muscle groupspowerful muscle groups..
Lout
Lin
Fulcrum
Vbl.trans.
Vblade
Vhandle
?Catch through
the stretcher
Vboat
Vbl.prop
In case of “Catch through the handle”:
Vblade = Vhandle (Lout / Lin)
In case of “Catch through the stretcher”:
Vblade = Vstr. ((Lout + Lin) / Lin)
Catch through
the handleVstretcher
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Drive ->
Using of the most powerful muscle Using of the most powerful muscle
groupsgroups
The legs start the
movement
The trunk continue andaccelerate the
movement
The arms finalize the
movement
Velocity
Angle
The most effective sequence
of the segments:
< -Recovery
The sequence is mirrored
during recovery
Strong posture: effective back curveStrong posture: effective back curve
�Straighter lumbar area
can help to transfer the
force better from hips to
shoulders and prevent
injuries;
�more curvature in the
thoracic area can be
more economical
because it uses more
elastic properties of the
muscles rather then its
strength.
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Drysdale
Waddell
Analysis of Lumbar and Thoracic anglesAnalysis of Lumbar and Thoracic angles
� The best scullers
have significantly
straighter lumbar
angles and more curved thoracic angle
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1515
150
160
170
180
Lumbar Angle α (deg)
140
150
160
170
180
Catch Middle Finish
Thoracic Angle β (deg)
Tufte Neykova
Drysdale Karsten
Waddell
β
α
A
B
C
D
E
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Advantages of the front loadedAdvantages of the front loaded--drivedrive
FrontFront--loaded drive (F1):loaded drive (F1):
�� Gives 47% higher average Gives 47% higher average
velocity and distance velocity and distance
travelled during the drive;travelled during the drive;
�� Creates much more even Creates much more even
distribution of the power;distribution of the power;
�� Provide better utilization of Provide better utilization of
the most powerful muscle the most powerful muscle
groupsgroups
�� HydroHydro--lift force on the blade lift force on the blade
can be used better.can be used better.
0
2
4
6 F1F2F3
Force (N)
0
5
10
15
V1
V2
V3
Velocity (m/s)
0
20
40
60
80P1P2P3
Power (W)
0
20
40
60 P1P2P3
Distance
travelled (m)
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How the frontHow the front--loaded drive looks like?loaded drive looks like?�� It is important to It is important to
increase force increase force
quickly up to 70% of quickly up to 70% of
maximum;maximum;
�� ““TrampoliningTrampolining””
effect?effect?
1. Front-loaded 1. Middle-loaded
1
2
Drive
Force/Body mass (N/kg)
1
2
Boat
Acceleration
1
2
Boat Velocity
R3-D1 D2 D3 D4
www.biorow.comwww.biorow.comR2 R3 D1
D2
D3 D4 D5 D6 R1 R2
Gate
Stretcher
Force
BoatRowerSystem
Acceleration
`
Legs TrunkArms Handle
Velocity
Vertical angleBoat speed
DriveDrive D1 D1 Blade immersion;Blade immersion;
D2 Initial RowerD2 Initial Rower’’s Accelerations Acceleration
�� CatchCatch:: the oar change the the oar change the
direction of the movement by direction of the movement by
means of legs kick through means of legs kick through
the stretcher.the stretcher.
www.biorow.comwww.biorow.comR2 R3 D1
D2
D3 D4 D5 D6 R1 R2
Gate
Stretcher
Force
BoatRowerSystem
Acceleration
`
Legs TrunkArms Handle
Velocity
Vertical angleBoat speed
DriveDrive DD3 3 Initial Boat Initial Boat
Acceleration Acceleration
�� Extending knees using Extending knees using
quads,quads,
�� Pushing the stretcher Pushing the stretcher
through toes.through toes.
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FinishFinish
1.1. ““Finish through the handleFinish through the handle”” creates additional force of the blade, which creates additional force of the blade, which
propels the boatpropels the boat--rower system;rower system;
2.2. ““Finish through the handleFinish through the handle”” does not push the boat down;does not push the boat down;
3.3. ““Finish through the handleFinish through the handle”” uses more effective leverage of the oaruses more effective leverage of the oar,,
4.4. ““Finish through the handleFinish through the handle”” allows earlier relaxation of the legs muscles.allows earlier relaxation of the legs muscles.
�� ““Finish through the handleFinish through the handle”” is the only effective way to finish is the only effective way to finish
the drive!the drive!
Fblade
Fstrertcher.
Mинерт.
Fhandle
G.
Fstr.vert.
Finert.
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Biomechanically based rowing drillsBiomechanically based rowing drillsDrillDrill PurposePurpose
11 Rowing with feet Rowing with feet
outoutEmphasise the stretcher pressure and Emphasise the stretcher pressure and
fast arms drive at finish of the drivefast arms drive at finish of the drive
22 Late squaring of Late squaring of
the bladesthe bladesPreventing feathering in the water and Preventing feathering in the water and
developing good balancedeveloping good balance
33 Arms with Arms with
shouldersshouldersActive using of the shoulders, arms Active using of the shoulders, arms ––
shoulders coordination.shoulders coordination.
44 ¼¼ slide slide –– fast fast
trunktrunkPush the stretcher through heels Push the stretcher through heels
using gluts and hamstrings, fast using gluts and hamstrings, fast
horizontal trunk drivehorizontal trunk drive
55 Catch Catch –– legs legs
onlyonlyFast blade placement into the Fast blade placement into the
water, quick kick to the stretcher water, quick kick to the stretcher
through toes using quadsthrough toes using quads
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Catch Catch –– legs only drilllegs only drill
�� Fast blade placement into the water, quick kick Fast blade placement into the water, quick kick
to the stretcher through toes using quadsto the stretcher through toes using quads
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Fast trunk drillFast trunk drill
�� Push the stretcher through heels using gluts Push the stretcher through heels using gluts
and hamstrings, fast horizontal trunk driveand hamstrings, fast horizontal trunk drive
Biomechanical basics of riggingBiomechanical basics of rigging
We will discuss:We will discuss:
��Oar dimensions;Oar dimensions;
��Gearing ratio;Gearing ratio;
��Span/spread and;Span/spread and;
��Gate height and Gate height and
pitch;pitch;
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Spread (sweep)
Gate Height
Seat Height from water
Heels Depth
Span (sculling)
Overlap (sculling)
Overlap (Sweep)
StretcherAngle
Work through
Pitch
Seat Travel
Gate Height
Stretcher position
SlidesAngle
Definition of the GearingDefinition of the Gearing
�� The standard definition of the The standard definition of the
gearing is the ration of gearing is the ration of
velocities (or displacements, velocities (or displacements,
travels) of output to input;travels) of output to input;
�� In rowing, velocity of the In rowing, velocity of the
output is defined by actual output is defined by actual
outboard, input outboard, input –– by actual by actual
inboard;inboard;
�� The span/spread does NOT The span/spread does NOT
affect gearing;affect gearing;
�� Blade efficiency or Blade efficiency or ““slippageslippage””
DOES affect Gearing.DOES affect Gearing.
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2525
Gearing = Actual Outboard / Actual Inboard
= (Out.-SL/2- SW/2) / (Inb.-Hnd/2+SW/2)
Blade Travel
Handle Travel
Oar LengthInboard
PinActual Inboard
Oar LengthInboard
Actual OutboardPin
Dynamic GearingDynamic Gearing
�� At sharp oar angles only part of At sharp oar angles only part of
blade velocity is parallel to the blade velocity is parallel to the
boat velocity;boat velocity;
�� Effect of the oar angle is small Effect of the oar angle is small
until 45deg;until 45deg;
�� Gearing ratio became twice Gearing ratio became twice
heavier at the oar angle 60deg;heavier at the oar angle 60deg;
�� Gearing ratio became three Gearing ratio became three
times heavier at the oar angle times heavier at the oar angle
60deg;60deg;
�� Gearing ratio became six times Gearing ratio became six times
heavier at the oar angle 60deg;heavier at the oar angle 60deg;
�� The most common catch angles The most common catch angles
are between 55deg (sweep) are between 55deg (sweep)
and 70deg (sculling).and 70deg (sculling).
0
1
2
3
4
5
6
7
8
9
10
11
12
0 10 20 30 40 50 60 70 80
Dynamic Gearing Ratio
(Outboard/Inboard)
Oar Angle (deg)
G(a) = G/cos(a)
Handle Velocity
Blade Velocity
Boat Velocity
The span affects gearing indirectlyThe span affects gearing indirectly
Effect of the span on the catch angle:Effect of the span on the catch angle:
��Two centimetres of shorter spread gives only 0.5 deg of extra Two centimetres of shorter spread gives only 0.5 deg of extra
catch angle;catch angle;
��If we change inboard accordingly to maintain overlap, this If we change inboard accordingly to maintain overlap, this
would gives us 0.8 deg of extra catch angle for every 2cm of would gives us 0.8 deg of extra catch angle for every 2cm of
extra spread.extra spread.
ab
∠a > ∠b
A
B
B > A
““CostCost”” of one degree of the oar angle at catch, of one degree of the oar angle at catch,
when change the stretcher positionwhen change the stretcher position
�� One degree equal about 1.5cm of the arc length in One degree equal about 1.5cm of the arc length in sculling and 1.75cm in sweep rowingsculling and 1.75cm in sweep rowing
�� Change of the stretcher position affects more catch Change of the stretcher position affects more catch angle than finish angleangle than finish angle
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
0 10 20 30 40 50 60 70 80
“Cost” (cm/degree)
Catch Angle (deg)
Rigging Calculator Rigging Calculator
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2929
The difference in force lever is the main reason The difference in force lever is the main reason
of boat rotation in a pairof boat rotation in a pair
Lever of force of bow rower is longer
Centre ofthe shell
Bow
lever
Stroke
lever
Levers are equal
Centre ofthe shell
Bow
lever
Stroke
leverCentre ofthe shell
Bow
lever
Stroke
lever
Catch
Middle of
the drive Finish
Lever of force of stroke rower is longer
Coordination of forces in a pairCoordination of forces in a pair
To prevent rotation To prevent rotation
of the boat:of the boat:
��Stroke rower must Stroke rower must
apply higher force at apply higher force at
catch;catch;
��Bow rower must Bow rower must
apply higher force at apply higher force at
finish;finish;-100
0
100
200
300
400
500
600
700
800
-60 -40 -20 0 20 40
Stroke
Bow
A (deg)
Handle Force (N)
��Average force of the Average force of the
stroke rower must be stroke rower must be
about 5% higher than about 5% higher than
of the bow rowerof the bow rower0%
20%
40%
60%
-60 -40 -20 0 20 40
Bow L.
StrokeF1
StrokeF2
Str.L.BowF1
BowF2
Ratio of Levers and Forces (%)
Oar Angle (deg)
Big boats with the normal rigBig boats with the normal rig
�� In the four and eight with In the four and eight with
the normal rig the sum of the normal rig the sum of
the levers turns the bow to the levers turns the bow to
the port side;the port side;
�� The stroke rower can turn The stroke rower can turn
the eight at catch to the the eight at catch to the
same side;same side;
Each stroke with synchronous Each stroke with synchronous
force application creates force application creates
the boat yaw angle:the boat yaw angle:
�� 0.37 deg in a pair, 0.37 deg in a pair,
�� 0.076 deg in the four,0.076 deg in the four,
�� 0.015 deg in the eight0.015 deg in the eight
RR
Fbl
Fbl
R
Fbl
R
Levers of the blade force in
the pair, four and eight
. Mass moments of inertia
in various boat types (kg m2)
1076074003360Eight
1125882243Four
1038815Pair
Total
Rower
sBoat
The normal and Italian rigs in the fourThe normal and Italian rigs in the four
�� In the Italian rig the sum of levers is zero, so the boat goes In the Italian rig the sum of levers is zero, so the boat goes straight at the equal force application;straight at the equal force application;
�� The boat with normal rig can go straight, if stroke rowers The boat with normal rig can go straight, if stroke rowers apply force earlier and/or higher (5% difference in the apply force earlier and/or higher (5% difference in the average force).average force).
-6
-4
-2
0
2
4
6
-60 -40 -20 0 20 40
4 32 1Sum
Lever (m)
Oar angle (deg)Seat:
4
3
2
1
-6
-4
-2
0
2
4
6
-60 -40 -20 0 20 40
4 32 1Sum
Lever (m)
Oar angle (deg)Seat:
14
3 2
Normal rig Italian rig
Average levers in fours (in meters)
0.003.36-3.13-2.902.66Italian
-0.47-3.363.13-2.902.66Normal
Sum1234Seat
0
200
400
600
800
1000
-60 -40 -20 0 20 40
Stroke and 2 seat
3 seat and bow
Handle Force (N)
Oar Angle (deg)
Effect of the span on the torque in pairEffect of the span on the torque in pair
�� A rower with longer A rower with longer span produces span produces higher torque higher torque relative to the relative to the centre of the boat centre of the boat (CB) at the same (CB) at the same force (or the same force (or the same torque at lower torque at lower force);force);
�� This in not a real This in not a real ““gearinggearing”” because the ratio of because the ratio of
velocities and forces on the handle and the velocities and forces on the handle and the
blade remains the same irrelative to the span.blade remains the same irrelative to the span.
Levers
Catch
Bow.
Stroke.
Finish
Bow.
Stroke.
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Handle and seat forcesHandle and seat forces
�� Lift force depends on the Lift force depends on the
height of the handle height of the handle
relative to footrelative to foot--stretcherstretcher::
Flift = H / Lw * Fh
�� Handle force is limited at Handle force is limited at
certain handle height and certain handle height and
rowerrower’’s weight:s weight:
Fh.max = Lw / H *W
�� Seat force can be good Seat force can be good
indicator of rowing indicator of rowing
technique.technique.
Good
Bad
Seat Force (N)
Angle (deg)
Rower’s Weight
Recovery
Recovery
CMW
H
Lw
Fh
Flift
MhCM
Fhr
Gate height and pitchGate height and pitch
� In case of the most common pitch 4 deg, only 0.24% of the propulsive force is lost;
� the height of the handle (and gate) is defined mainly by a comfort for a rower at finish;
� a lower gate height requires more pitch and more significant arms “grubbing and vice versa;
� Lateral pitch is useful to overcome the difference in comfortable height of the handle.
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3636
12deg
4deg
Pitch
angle
Biomechanical Tools and DevicesBiomechanical Tools and Devices
�� Telemetry system;Telemetry system;
�� Immediate feedback Immediate feedback
tools;tools;
�� ““Stroke coachesStroke coaches”” and and
““boat checkboat check”” meters;meters;
�� Mobile rowing tank. Mobile rowing tank.
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3737
BioRowTel Telemetry System v.4.5BioRowTel Telemetry System v.4.5
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� The system is quick to setup (30-90 min for 1x - 8+) and remove. It does not affect any rigging settings, which is
important before regattas.
� Two-dimensional (2D) oar angle sensor measures position of the oar shaft in horizontal and vertical planes, which allows to define a path of the blade relative to water.
� Position sensors of the seat and shoulders allow to derive their velocities and power, which defines a rowing style.
-9
-6
0
3
6
-50 -25 2
5
1
2
Horizontal Angle
Vertical Angle
Catch Slip
Release Slip
Water Level
Recovery
Drive
Catch
Finish 3 -3
Averaging
-
2
-
1
0
1
2
Legs
Trunk
Arms
Handle
Velocity (m/s)
Time
Adam
DDR Rosenberg
Ivanov
Analysis
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Visual Immediate Feedback System:Visual Immediate Feedback System:
��The System can be used with any standard video camera. The The System can be used with any standard video camera. The
transmitter is attached to the video camera. VFS system worn by transmitter is attached to the video camera. VFS system worn by the the
athlete and the integral headphones allow the coachathlete and the integral headphones allow the coach’’s comments to be s comments to be
heard. heard.
��VFS can be used for immediate feedback on various elements of VFS can be used for immediate feedback on various elements of
technique: oar blade work, leg work, arm work, synchronization otechnique: oar blade work, leg work, arm work, synchronization of the f the
crew, etc.crew, etc.
Pattern of boat acceleration as a fingertipPattern of boat acceleration as a fingertip
� Magnitudes of both negative peak and the first peak of the boat acceleration are highly dependent on the stroke rate.
� No significant difference was found between sculling and sweep rowing.
� The pattern is quite similar in all boat sizes.
� The best rowing crews have
the highest magnitude of the negative peak of the boat acceleration at catch and the highest first peak.
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-12
-9
-6
-3
0
3
6
9
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
Olympic Champions LM2x
National level LM2x
Drive
Boat Acceleration (m/s2)
Time (s)
Catch Finish
RecoveryRecovery
LM2x at 35 str/min
-15
-12
-9
-6
-3
0
3
6
9
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Olympic Champions M2-
National level M2-
Drive
Boat Acceleration (m/s2)
Time (s)
Catch Finish
Recovery Recovery
M2- at 39 str/min
-15
-10
-5
0
5
10
Time
(% of cycle)
Boat Acceleration (m/s2)
Catch Finish
Zero
before
catch
Negative
peak.
Zero
after
catch
First
peak
Drive
humpSecond
peak
New New ““check factorcheck factor”” for for
ActiveTime ActiveTime ™™ stroke rate meterstroke rate meter
� Delta boat acceleration (DA) was selected as the most appropriate parameter for evaluation of technical skills of the crew.
� New algorithm was developed and implemented in the latest version of
ActiveTime ActiveTime ™™ stroke rate meter.stroke rate meter.
� The quality of each stroke is displayed as a score F from 0 to 100:
0-20 – Beginners
20-40 - Club rowers;
40-60 - National level;
60-80 - International level;
80-100 - Champions www.biorow.comwww.biorow.com
Rowing MachinesRowing Machines
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4242
M = ∞
Mr.
F inertia
F inertia
Mr.
F inertia
F inertia
M flywheel = M boat
= 17kg
0
200
400
600
800F handle
F stretcher
F(N)
T
0
200
400
600
800F handle
F stretcher
F(N)
T
RowPerfect
Concept 2
Catch Drive Release
Mobile Rowing Tank (MRT)Mobile Rowing Tank (MRT) ©©19891989--2008 Dr. Valery Kleshnev2008 Dr. Valery Kleshnev
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Advantages of MRT compare to a
stationary tank:
�There is power transfer through the
stretcher, which contribute nearly 40% of
power production in on-water rowing.
�There is a gearing effect similar to on-water rowing, where the stretcher force is
40% higher than the handle force.
�Similar to on-water rowing, MRT requires
more legs power, while stationary rowing requires more upper body power.
�The stretcher acceleration makes
vestibular sensations of the rower very similar to the sensations during on-water
rowing.
�Rowers can interact through the stretcher to develop an accurate synchronisation,
similar to on-water rowing.
V+
Fdrag
Fprop
Water tank
Mobile rower’s
workplace
Resistanceunit
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Thank you for attentionThank you for attention
�� Dr. Valery KleshnevDr. Valery Kleshnev
�� Rowing Science ConsultantRowing Science Consultant
�� ee--mail: mail: [email protected]@btinternet.com
�� Rowing Biomechanics NewsletterRowing Biomechanics Newsletter
�� www.biorow.comwww.biorow.com