2011 11 kleshnev rowing biomechanics

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Biomechanics for Effective RowingTechnique

Dr. Valery KleshnevDr. Valery KleshnevRowing Science ConsultantRowing Science ConsultantBioRowBioRow [email protected]@btinternet.com

2011 WORLD ROWING COACHES CONFERENCE

10-13 November 2011, Varese, Italy

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Basic chart of Rowing BiomechanicsBasic chart of Rowing Biomechanics

Medal

Work capacity(Physiology)

Technique(Biomechanics)

Motivation(Psychology)

Life Style(Management)

EfficiencyEffectiveness

Rowing Style /Rower’s Efficiency

BladeEfficiency

Dynamics of the system

BoatEfficiency

Rowing Power

Segments’Velocities Rigging

Force Curve Boat Velocity& Acceleration

Standards(Stroke Rate,

Length, Force)

Performance Level

Analysis Level

Measurement Level

Vertical OarAngle

From: Kleshnev V. 2011. Rowing Biomechanics. In: Rowing Faster, the 2nd edition, ed. Nolte V. Human Kinetics

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http://www.BioRow.com

http://www.BioRow.com

mailto:[email protected]




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What we are going to talk about?What we are going to talk about?

üü Biomechanical Biomechanical ““Gold StandardsGold Standards””;;

üü Tools for biomechanical measurements in rowing;Tools for biomechanical measurements in rowing;

üü Force curve and dynamics of the system;Force curve and dynamics of the system;

üü SegmentSegment’’s velocities and rowing styles;s velocities and rowing styles;

üü Vertical angle and blade efficiency;Vertical angle and blade efficiency;

üü Biomechanics for rigging.Biomechanics for rigging.

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What are Rowing Biomechanics What are Rowing Biomechanics ““Gold StandardsGold Standards””??

Pprop = DF * V3

P = Pprop / EbladeL = Inb. * A WPS = P * (60 / Rate)Fav = 0.83 * WPS / L

7043669040.01.1547005:46.2LM4-75639311037.00.8847006:07.2LM2x58330310635.00.8833006:47.0LW2x7974149440.01.1455005:18.6M8+8064199240.01.1555005:41.0M4-8594479038.01.1655006:16.5M2-82042611439.00.8755005:33.2M4x85444411437.00.8855006:02.1M2x89246411435.00.8955006:32.5M1x6013139239.01.1540005:53.1W8+6413349037.01.1640006:52.9W2-65133911037.00.8740006:08.5W4x68035411035.00.8840006:39.5W2x71337111033.00.8940007:11.5W1x

Fmax (N)Fav (N)Angle (deg)Rate (1/min)Inb. (m)P (W)G.St.

TimeEvent

70609585

W (kg)

6:03470LW Men6:48330LW Women5:44550Open Men6:23400Open Women

Erg Score (m:s)P (W)Category



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What Biomechanical Tools we use?What Biomechanical Tools we use?üü BioRowTelBioRowTel v4.5 telemetry system v4.5 telemetry system

was created by rowing scientist was created by rowing scientist for research purposes. It is for research purposes. It is accurate, flexible, scalable, based accurate, flexible, scalable, based on on ““screeningscreening”” concept, quick to concept, quick to setup, light;setup, light;

üü Scalable design: one Scalable design: one ““MasterMaster””unit + up to 8 unit + up to 8 ““SlavesSlaves””;;

Master unit contains: Master unit contains: üü GPS and impeller input for boat GPS and impeller input for boat

speed;speed;üü 3D accelerometer, 3D gyro;3D accelerometer, 3D gyro;üü Wind speed & direction input;Wind speed & direction input;üü Sampling frequency 25Sampling frequency 25--100 Hz;100 Hz;üü Resolution 14 bit;Resolution 14 bit;üü Works >8 hours;Works >8 hours;üü Weight 300g.Weight 300g.


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“Master” unit “Slave” unit

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19871988

19922001

2011

Our history force measurements in rowing

1998

Instrumented gates

Oar bend sensors

HandleOar Shaft Insert

Strain Gauges“+” “-“

2002

2005

2010 Wireless

StretcherForcesensors

2001

2005

Seat Force sensor 2002

2005



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What is measured with force transducers?

ü Handle Force gives the most accurate power measures, but require calibration of every oar.

ü Gate force require inboard for power calculation, which could vary during the drive ±5%;

ü Pin Force is affected by oar angle and axial force, so power could me measured with ±20% accuracy.

Peach Inn. Ltd.

Our gates, WEBA gate

HandleForce

Our sensors, FES sensor

Pin Force Gate

Force

Axial Force

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How we process data with How we process data with BioRowTelBioRowTel systemsystem


Averaging

-

2

-

1

0

1

2

Legs

Trunk

Arms

Handle

Velocity (m/s)

Time

Adam

DDR Rosenberg

Ivanov-Grinko

Analysis

-100

0

100200

300

400

500600

700

800

-75 -50 -25 0 25 50

24/11/10

03/11/11

Handle Force (N)

Date

Averaging algorithm implemented in the software allows:

ü Unambiguous analysis of massive rowing data,

ü Easy comparison of various samples: rowers in the boat, various stroke rates, previous and current data;

ü Accuracy <1%.



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How can we present the Force Curve?ü Force vs. time (s) is good for

synchronisation with other variables, but difficult to compare at various stroke rates;

ü Force vs. time (% of stroke cycle) is another option;

ü Force vs. Oar Angle allows easy comparison at various stroke rates and useful for defining position of specific points (peaks, gaps).

-1000

100200300400500600700

800

0.0 0.5 1.0 1.5 2.0 2.5

212529333739

Time (s)

Handle Force (N) Stroke Rate (1/min)

-1000

100200300400500600700

800

0% 20% 40% 60% 80% 100%

212529333739

Time (% of cycle)


-100

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600

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-75 -50 -25 0 25 50

212529333739

Oar Angle (deg)


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Why the front loadedWhy the front loaded--drive is more effective?drive is more effective?

FrontFront--loaded drive (F1):loaded drive (F1):üü Gives 47% higher average Gives 47% higher average

velocity and distance velocity and distance travelled during the drive;travelled during the drive;

üü Creates much more even Creates much more even distribution of the power;distribution of the power;

üü Provide better utilization of Provide better utilization of the most powerful muscle the most powerful muscle groupsgroups

üü HydroHydro--lift force on the blade lift force on the blade can be used better.can be used better.

0

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Force (N)

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V1V2V3

Velocity (m/s)

0

20

40

60

80 P1P2P3

Power (W)

0

20

40

60 P1P2P3

Distancetravelled (m)



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How the frontHow the front--loaded drive looks like?loaded drive looks like?üü It is important to It is important to

increase force increase force quickly up to 70% of quickly up to 70% of maximum;maximum;

üü ““TrampoliningTrampolining””effect?effect?

1. Front-loaded 1. Middle-loaded

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2

Drive

Force/Body mass (N/kg)

1

2

Boat Acceleration

1

2

Boat Velocity

R3-D1 D2 D3 D4

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How can we analyse the Force Curve?

ü Catch gradient defines how quickly the force increases;ü Position of the Peak Force defines emphasis of force

application;ü Finish gradient defines how long the force maintained.

0%

20%

40%

60%

80%

100%

0% 20% 40% 60% 80% 100%

Norm.Oar Angle (% to total)

Normalized Force (% of Max.)

70% of Max.

Catch Gradient Finish

Gradient

Position of Peak Force



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How the Target Force Curve looks like?

ü Solid, front-loaded, full, no “humps” or glitches.ü Catch gradient 10% of the Total Angle (11 deg in sculling, 9 deg in

rowing);ü Position of the Peak Force 33% of Total Angle (down to 30% in 8+ and

4x, up to 38% in 1x);ü Finish gradient 32% (up to 36% in big boats, down to 26% in small

boats).

0%

20%

40%

60%

80%

100%

0% 20% 40% 60% 80% 100%

Norm.Oar Angle (deg)

Normalized Force (% of Max.)

70% of Max.Force

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How we analyze rower’s blade work?

ü Two-dimensional (2D) sensor measures oar angles horizontal and vertical planes, which allows to define a path of the blade relative to water.

ü Criterion -3 deg was chosen to indicate full immersion of the blade into the water.

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0

3

- 50 - 25

Vertical Angle (deg)

Catch Slip

Release Slip

Water Level

Recovery

Effective Angle

Catch Finish

3Drive

Target Curve

Horizontal Angle (deg)

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What we need to know about blade efficiency?ü Hydro-lift force works at sharp angles of

attack and contributes 56% of the blade propulsive force;

ü Drag force works at the middle of the drive and contributes 44% of the blade propulsive force.

How can we increase the blade propulsive efficiency?

ü Use bigger blade area;

ü Use heavier gearing;

ü Utilise hydro-lift effect -> apply more

force at sharp oar angles at catch;

ü Place the blade at the optimal depth

under the water (4-6 deg).70%

80%

90%

100%

-75 -50 -25 0 25 50

Blade Efficiency (%)

Oar Angle (deg)

50

100

150FliftFdragFblade total

Force (N)

30

60

90Angle of attack (deg)

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3

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VbladeVboat

Velocity (m/s)

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How we measure velocities of body segments?

ü Cable position transducers are attached to the seat and top of the trunk (at the level L7-Th1 vertebra or sternum-clavicle joints);

ü Arms velocity is calculated as a difference between handle velocity (derived from oar angle and inboard) and trunk velocity.

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Why “humps” of the Force Curve happen?üUsually, the hump

happens at about ¼ of the drive after the catch;üThe most common

reason is early “opening”the trunk at catch, followed by a “hump” of trunk speed;üThe handle is driven

upwards, the blade goes down and creates very heavy resistance, which do not allow rower to “push through”.

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

0 10 20 30 40 50

Handle

LegsTrunkArms

Frame N

Velocity (m/s)-100

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700

0 10 20 30 40 50

Frame N

Force (N)

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-3

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0 10 20 30 40 50

12Boat TiltDrive

Frame N

Vertical Angle + Boat Tilt (deg)

Positive Tilt means left side up

Catch Finish

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How effective sequence of segments looks like?

ü Legs start the drive with velocity equal to the handle velocity;üTrunk starts at the knee

angle about 90 deg (handle position on top of the stretcher);üArms and shoulders

starts slowly soon after the trunk and accelerates at the finish.

Frame N

-100

0

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700

0 10 20 30 40 50

Frame N

Force (N)

-4.0

-3.0

-2.0

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1.0

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Handle

LegsTrunkArms

Velocity (m/s)

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-3

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0 10 20 30 40 50

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Frame N

Vertical Angle (deg)

Catch Finish

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How segments sequence defines Rowing Style?How segments sequence defines Rowing Style?

Adam style

DDR style Rosenberg style

Ivanov-Grinkostyle

Legs Emphasis

Simultaneous Timing Consequent Timing

Trunk Emphasis

A popular classification of Rowing Styles by Peter Klavora (1979) and appended (RBN 2006/03) classify techniques on the basis of legs-trunk coordination and emphasis during the drive.

0500

10001500200025003000

TotalLegsTrunkArms

Adam style

Угол

Power (W)

0500

10001500200025003000

TotalLegsTrunkArms

Ivanov-Grinko style

Angle

Power (W)

0500

10001500200025003000

TotalLegsTrunkArms

Rosenberg style

Angle

Power (W)

0500

10001500200025003000

TotalLegsTrunkArms

DDR style

Angle

Power (W)

2020

The 1st reason to start with legs: muscles-antagonists

Quads

GlutsHamstrings

Vastusintermedius

SartoriusSemi-tendinosus

Bicepsfemoris

Both front and back of thigh has biarticulate muscles:•Quads (Rectus femoris & Sartorius) are connected to the shins and (partly) to the pelvis;Hamstrings (Biceps femoris long head & Semi-tendinosus) are connected to the shins and to the pelvis



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The 2The 2ndnd reason to start with legs: reason to start with legs: ““Catch through the Catch through the stretcherstretcher””

üü ««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;

üü ««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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How fast legs reflects in the boat acceleration?How fast legs reflects in the boat acceleration?

ü Magnitudes of both negative peak and the first peak of the boat acceleration are highly dependent on the stroke rate.

ü No significant difference was found between sculling and sweep rowing.

ü The pattern is quite similar in all boat sizes.

ü 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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-3

0

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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

DriveBoat Acceleration (m/s2)

Time (s)

Catch FinishRecoveryRecovery

LM2x at 35 str/min

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-12

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-6

-3

0

3

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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 FinishRecovery Recovery

M2- at 39 str/min

-15-10-505

10

Time (% of cycle)

Boat Acceleration (m/s2)

Catch Finish

Zero before catch

Negative peak.

Zero after catch

First peak

Drive hump

Second peak





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When the trunk should start?

ü At the catch the force is applied through the toes, which decrease Lh and increase leverage around knee joint.

ü After 1/3 of the drive the point is shifted to the heels, which increase Lh(more lift of the rower’s weight) and decrease leverage around hip joint.

ü Ability to shift from the point of force application toes to heels and emphasis from quads to hamstrings is very important component ofrower’s skill.

VhHw

LF

LH

a) б ) в )

90 o

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How to perform effective Finish?How to perform effective Finish?

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.üü ““Finish through the handleFinish through the handle”” must be performed during the shortest must be performed during the shortest

possible time and travel of the handle.possible time and travel of the handle.

Fblade Fstrertcher.

M инерт.

Fhandle

G .

Fstr.vert.

Finert .

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

-75 -50 -25 0 25 50

LegsTrunkArmsTotal

Velocity (m/s)

Angle (deg)

Too early trunk return



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How can we deliver information to a rower in a How can we deliver information to a rower in a real time?real time?

üüVisual Feedback System VFS can be used with any standard Visual Feedback System VFS can be used with any standard video camera. The transmitter is attached to the video camera. video camera. The transmitter is attached to the video camera. VFS system worn by the athlete and the integral headphones VFS system worn by the athlete and the integral headphones allow the coachallow the coach’’s comments to be heard. s comments to be heard. üüVFS can be used for immediate feedback on various VFS can be used for immediate feedback on various elements of technique: oar blade work, leg work, arm work, elements of technique: oar blade work, leg work, arm work, synchronization of the crew, etc.synchronization of the crew, etc.

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Would you like to feel onWould you like to feel on--water rowing during winter?water rowing during winter?


Mobile Rowing Tank (MRT) allows:üPower transfer through the stretcher, which contribute nearly 40% of power production in on-water rowing.üThere is a gearing effect similar to on-water rowing, where the stretcher force is 40% higher than the handle force.üSimilar to on-water rowing, MRT requires more legs power, while stationary rowing requires more upper body power.üThe stretcher acceleration makes vestibular sensations of the rower very similar to the sensations during on-water rowing.üRowers can interact through the stretcher to develop an accurate synchronisation, similar to on-water rowing.

V+

Fdrag

Fprop

Water tank

Mobile rower’sworkplace

Resistanceunit





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What we can measure in rigging?What we can measure in rigging?Why rigging is important?Why rigging is important?üüOar dimensions define Oar dimensions define gearing, which determines gearing, which determines force/velocity ratio of force/velocity ratio of rowerrower’’s muscles s muscles contraction;contraction;üüStretcher position is Stretcher position is related to ratio of related to ratio of catch/finish angles;catch/finish angles;üüGate height and blade Gate height and blade pitch defines vertical oar pitch defines vertical oar angles;angles;üüStretcher angle and Stretcher angle and height defines lift force and height defines lift force and kinetics of the drive.kinetics of the drive.


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Spread (sweep)

Gate Height

Height from water

Heels Depth

Span (sculling)Overlap (sculling)

Overlap (Sweep)

StretcherAngle

Work through

Pitch

Seat Travel

Gate Height

Stretcher position

SlidesAngle

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What is correct definition of the Gearing?What is correct definition of the Gearing?

üü The standard definition of the The standard definition of the gearing is the ratio of gearing is the ratio of velocities (or displacements, velocities (or displacements, travels) of output to input;travels) of output to input;

üü 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;

üü The span/spread does NOT The span/spread does NOT affect gearing;affect gearing;

üü Blade efficiency or Blade efficiency or ““slippageslippage””DOES affect Gearing.DOES affect Gearing.


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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





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Is gearing constant during the drive?Is gearing constant during the drive?üü 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;

üü Effect of the oar angle is small Effect of the oar angle is small until 45deg;until 45deg;

üü Gearing ratio became twice Gearing ratio became twice heavier at the oar angle 60deg;heavier at the oar angle 60deg;

üü Gearing ratio became three Gearing ratio became three times heavier at the oar angle times heavier at the oar angle 70deg;70deg;

üü Gearing ratio became six times Gearing ratio became six times heavier at the oar angle 80deg;heavier at the oar angle 80deg;

üü The most common catch angles The most common catch angles are between 55deg (sweep) are between 55deg (sweep) and 70deg (sculling).and 70deg (sculling).

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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

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How can we help to optimize rigging?How can we help to optimize rigging?Rigging Calculator Rigging Calculator www.biorow.com/RigChart.aspxwww.biorow.com/RigChart.aspx


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Thanks to Ian Wilson of Concept2 UK for the idea and Dick & Peter Dreissigacker of Concept 2 for support.

http://www.biorow.com/RigChart.aspx

http://www.biorow.com/RigChart.aspx



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Thank you for attentionThank you for attention

üü Dr. Valery KleshnevDr. Valery Kleshnevüü Rowing ScientistRowing Scientistüü ee--mail: mail: [email protected]@btinternet.com

üüRowing Biomechanics NewsletterRowing Biomechanics Newsletterüü www.biorow.comwww.biorow.comüü www.biorow.orgwww.biorow.org







http://www.biorow.org

http://www.biorow.org

2011 11 kleshnev rowing biomechanics

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