The Question
What considerations must be implemented and considered when perfecting the rowing stroke? Understanding the biological system of the rower, as well as the design
of the mechanical system, the boat, and the motion dynamics of rowing, is vital
in order to achieve maximum boat velocity being applied to a quadscull within
rowing (Baudouin, A & Hawkins, D 2002). The following discusses what
biomechanical aspects influence a rowing stroke, as well as how this can be
used to achieve optimal, efficient technique.
The Answer
Rowing Technique and Sequence:
In order to understand how the rowing techniques can be improved, we
must understand the stroke phases essential to optimal technique. The break
down of the rowing technique begins with the grip, followed through to the
catch, drive, release and recovery.
The grip consists of the drive grip and the recovery grip. During the
drive stroke, the handle should be gripped with a flat wrist with the knuckles
at the base of the fingers in the middle of the handle. The fingers then roll
out during the recovery then squaring up once positioning at the catch. A
relaxed grip is used and the handle should not be held too firm at the end of
the handle with the thumbs on the end of the grip in sculling and during the
sweep, the outside hand at the end of the handle with the inside hand towards
the blue grip. The left hand should lead the right hand during the recovery
phase. During the drive, the hands should not change from the recovery that is
the right hand leading ahead of the left (Nolte, n.d; Kleshnev, 2010).
During the catch (the start of the drive phase), shins must be vertical
with the lower back tucked in sitting up slightly. Due to body differences that
we must consider (i.e. shorter rowers and taller rowers) variables such as:
more body length, less shin angle, etc. small variations may change to this
phase. The head must be straight with relaxed shoulders. Blades are placed in
the water and the boat is driven forward using the large muscle groups in the
legs and body (see figure 1). The body should be leaning forward and the body
close to the thighs. The hands are lifting upwards fully locking the blades in
the water (Kleshnev, 2010).
During the drive phase beginners may often feel, as though the arms are
doing majority of the work, however, this is not the case. Primarily the larger
leg muscles will be in action with the arms more relaxed with hands parallel to
the boat. Towards the end of the drive, the body (back) swings back and the
arms are then used to maintain momentum of the blade handles allowing for
continued acceleration of the blade through the water (Nolte, n.d).
During the release, the rower’s hands then make a small tap downwards
lifting the blades away from the water. The legs should be flat down with their
back straight however slightly leaning back creating a pull on the abdominal
muscles. The blade handles brush the body when the spoon end is flat on the
water. Blades are then feathered to become parallel to the water, which allows
for a more aerodynamic position. The recovery phase then begins (Nolte, n.d).
The recovery phase begins with the hands moving down and away in an
opposite sequence to the drive. The arms move away from the body vertically
balanced, with the shoulders neck and arms relaxed. This posture ensures
recovery from the exertion of the stroke and aids in keeping the boat balanced
in the water. The body then rocks on from the pelvis with straight back and
lifted knees allowing the seat to move (Nolte, n.d).
Figure 1: Muscles used during the catch, drive, release (finish) and
recovery (Mazzone, 1988).
Newton’s laws of motion:
There are three Newton’s laws of motion, all of which can be applied to
a rowing stroke.
Newton’s first Law of motion describes “Every body perseveres in its
state of rest, or of uniform motion in a right line, unless it is compelled to
change that state by forces impressed thereon” (Kuehn, K 2015). Newton’s second
law of motion states that “the alteration of motion is ever proportional to the
motive force impressed; and is made in the direction of the right line in which
that force is impressed” (Kuehn, K 2015).
Newton’s third law of motion states “to every action there is always
opposed to an equal reaction; or in the mutual actions of two bodies upon each
other are always equal, and directed to contrary parts” (Kuehn, K 2015). In
relation to rowing, in order to move a boat faster, its needs to overcome the
inertia of the boat against the water (1st Law), by having a force
applied against it (2nd law). To do this a large and direct force
needs to be applied against the water, which ultimately applies an equal and
opposite reaction force against the boat (3rd law). As the sum of
forces dictates our acceleration of the boat and the force of gravity acts
against it (Newton’s Law of Gravitation), it is important to produce large horizontal
forces in order to propel the boat forwards. Downward forces need to also be
applied to lift the boat out of the water, whilst also maximising horizontal
force production (Blazevich, A 2010).
Impulse-momentum relationship and momentum:
A boat is propelled through the water by the use of various muscle
groups, which ultimately produce a force which is then transferred to the water
by the oars, which are then free to rotate around a vertical axis (Caplan, N
& Gardner, T 2007). During the drive
phase, the force applied is inconsistent, due to the various muscle sizes and
groups used throughout the stroke. The ground reaction forces also vary
throughout the stroke. When a rower is positioned at the catch, blades in the
water and the balls of the feet in contact with the footplate, the force is then
predominately generated using the Gluteus Maximus and Quadriceps muscles. Force
is applied to the handles, and during the push phase all joints in the kinetic
chain move simultaneously in a single movement (Magias, T 2016).
This part of the rowing stroke is referred to as the “impact peak”, due
to being the initiator of power production (Blazevich, A 2010). As the rower
moves through the stroke, the force is directed from the ball of the foot to
the heal of the foot, as the legs begin to fully extend. Once the legs are
fully extended, the torso begins to open up, at the hips, and as the boat
continues to accelerate through the water, the arms begin to pull the handles
of the oars towards the chest, until the body is in line with the hips, at a
degree of 100-105˚, in relation to the torso to the femur (Korner, T 2016).
This stage of the drive sequence is referred to as the “finish” and is the
“propulsive peak” of the stroke as maximum propulsion is achieved. Separating
the rowing stroke into a sequence promotes optimal length as the body is fully
contracted at the catch, and separating the drive sequence, provides optimal
boat speed (Magias, T 2016). Following this the rower then returns back to the
catch, through the recovery sequence (Blazevich, A 2010).
If we want to increase the speed of the boat of a constant mass, we need
to increase the velocity and therefore momentum of the boat. To increase the
boats momentum, a greater amount of force needs to be applied. Therefore, when
a rower is positioned at the catch, with the blades positioned in the water,
the largest amount of force possible needs to be applied for the longest time
possible in order to produce maximum momentum; the greater the impulse, the
greater the change in momentum due to change in mass and in turn change in
velocity. This is referred to as the “impulse-momentum” relationship. Therefore
the muscle groups used throughout a rowing stroke need to exert a greater deal
of power or force. Long rowing strokes are also required in order to increase
the time available for the force to be applied, and to essentially increase the
impulse of the stroke. (Blazevich, A 2010).
Extra acceleration comes from the recoiling of elastics tissues, such as
tendons, which are stretched when the legs are compressed by vertical and
breaking forces, when sitting at the catch with the shoulders over the hips.
Whilst breaking force is intended to be minimised, nonetheless a small amount
of breaking force is required in order for the blades to effectively connect at
the beginning of a stroke, at the catch. This is particularly important, when
rowing at high speeds, which require a higher stroke rate, to ensure that
maximum connection is achieved, when fully compressed at the catch (Blazevich,
A 2010).
Torque and centre of mass:
The force applied to the oar handle, and also movement, is affected by
the joint strength and torque velocity of the rower. In order to maximise power,
which is sustainable, the rigging set-up and blade design are to be matched to
the rower’s joint torque-velocity characteristics. Coordination and timing are
key contributors in regards to overall system velocity (Baudouin, A &
Hawkins, D 2002). When force is applied to the foot plate, to accelerate the boat,
the boat attains horizontal velocity, with the movement of the boat being
represented by the centre of gravity. It is relatively difficult to balance a
rowing boat; therefore part of this requires the manipulation of body parts to
ultimately find the centre of mass, to therefore achieve balance. The body’s
centre of mass within the boat lies within the base of support, between two
level hand heights when sitting at the catch. If the centre of mass moves
outside the base of support, either by moving the knees in one direction or
having unequal handle heights (determined by blade height of the water), this
essentially minimises the base of support, and ultimately balance is not
achieved (Blazevich, A 2010).
Angular Kinetics:
To return the body back to the catch, from the finish position, we need
to overcome inertia. As the torso swings over at the hips, moment of inertia is
applied. Moment of inertia describes the propensity for masses, which are at a
distance from the centre of rotation, to resist changes in their state of
motion. As the boat is moving in a straight line, mass and inertia are similar.
The change in oar length and weight can ultimately determine the inertia of the
oar. Increasing the length of the oar reduces the distance from the hands, when
sitting at the catch, and ultimately the centre of rotation to the main mass of
the oar, essentially reducing the oars moment of inertia. Reducing the length
of the oar, allows for increased length forward, into the catch, essentially
allowing for maximised boat connection (Blazevich, A 2010).
Muscle force and joint movements depends greatly on the velocity of the
movement. As joint velocity increases, muscle torque produced about the joints
decrease. Effort level ultimately determines the optimal angular velocities for
power production. Stroke rate and
rigging set-up can also determine angular velocities, through examining a
rower’s joint torque-velocity and torque-angle profiles. This therefore allows
for power delivery to be increased through lever action of the oar in order to
provide maximum sustainable power throughout the stroke (Baudouin, A &
Hawkins, D 2002).
Angular acceleration of an object will be greater if torque is increased
or the moment of inertia is decreased. In a rowing stroke, force is applied at
the hip joint through the Gluteus Maximus and quadriceps muscles, essentially
this is torque. The “moment arm” refers to the distance between the muscle and
the joint centre.
The greater this is, the more torque which can be generated about the
hip joint (see figure 2) for a given lever of muscle force. Moment arm can
evidently not be changed through training; muscle forces however can be
improved. Within rowing, increasing torque essentially increases angular
velocity of the leg and therefore the speed at which the foot comes in full
contact with the foot plate. Full contact of the feet to the foot plate is
optimal as surface area is increased, and maximum force can be produced
(Blazevich, A 2010).
Figure 2: Hip Angle
Work, power and energy:
The amount of work or energy supplied during a single rowing stroke is
equal to the average force that is applied, multiplied by the distance of which
the boat moves (Blazevich, A 2010). To increase power results in an increase in
boat velocity, however a single rowing stroke can be relatively draining in
terms of energy. Therefore mechanical energy and metabolic energy are two
factors which are taken into consideration in order to perform a great deal of
work with little energy cost. Mechanical energy, in relation to rowing, refers to
the energy which is associated with a boats movement, kinetic energy, or its
position, potential energy. An increase in velocity, results in an increase in
kinetic energy; the more power which is produced, the greater the velocity, and
the greater the kinetic energy which is produced as a result.
To improve rowing
efficiency, kinetic energy (output) needs to be increased, and the energy
required (input) to move the boat needs to be decreased. To ultimately improve
the efficiency of a rowing stroke, technique can be changed, however this
varies depending on the individual and their body type and composition.
Efficiency can also be improved through physical training. An individual can
improve their physical fitness in order to perform and train harder for longer.
The ultimate aim for a rower is to increase power output whilst also improving
and maintaining efficiency (Magias, T 2016).
Gravity, buoyancy, drag and propulsion:
There are four forces that act on a boat throughout a rowing stroke,
these include: gravitational, buoyant, drag, and propulsive.
Figure 3: The four forces acting on a boat shell (Baudouin &
Hawkins, 2002).
In the horizontal direction, propulsion and drag are the two acting
forces (Baudouin, A & Hawkins, D 2002). Drag is a force, which resists
motion, and propulsion assists with motion. Based on Newton’s 3rd
Law, action-reaction, to propel the boat forwards, a backward force must also
be applied. Reaction power is not equal and opposite to that of action power in
rowing. This is because water is not a solid, and therefore it moves when force
is applied. Therefore not all power which is applied, is not used to propel the
boat forwards, some is used to induce movement in the water, as the blade
enters the water (Blazevich, A 2010). In order for efficient rowing technique
to be applied, in terms of blade entry, the blade must enter and make
connection with the water ¾ up the slide, during the recovery phase. The blade
enters the water at the maximum point of reach during the catch phase in order
to take the drive directly up without “missing water” and disturbing the boat
force. This will then result in a late catch shorter effective stroke causing
less acceleration developed resulting a lower boat speed.
Hydrodynamic drag is created during a rowing stroke, and consists of
three drag quantities; skin, form and wave drag. This is a force that occurs
when the boat moves through the water at the interface of air and water with
different densities. The wave essentially applies an opposing force against the
boat, and in turn the turbulence, which is created ultimately, slows down boat
velocity, as well as increases the energy required to row at a given speed. Drag
is ultimately affected by frontal surface area and the shape of the boat
(Blazevich, A. 2010).
The faster the boats speed, the greater the drag (Blazevich, A. 2010). Blade
force is the only form of propulsive force to counter both air drag and
hydrodynamic drag (Baudouin, A & Hawkins, D 2002). Propulsive forces are
applied in order to overcome the water resistance placed on the shell of the
boat, as well as the air drag being applied to the rower and the oars. This
essentially applies to Newton’s second law of motion (Caplan, N & Gardner,
T 2007). Research suggests that in order to reduce the impacts of drag,
technique is a contributing factor in order to provide efficiency. Boat size
and weight is also a determining factor that determines the size and effect of
drag (Blazevich, A 2010). In the vertical direction, buoyancy and gravity are
acting on the combined mass of the boat, the rower, and the oar, in order to
achieve equilibrium (Baudouin, A & Hawkins, D 2002). In rowing, the underbellies
of the boats are designed in order to provide optimal lift, and minimal drag. Evidently, the heavier the boat, and crew members,
the lower the boats sits in the water, creating more drag, and in essence; the
lighter the boat, and the crew, the less drag created (Blazevich, A 2010).
There is however a mandatory boat weight for a quad in rowing competitions of
52kg (New South Wales, 2004).
Kinetic chain:
A push-like movement pattern is used during the drive phase, where all
joints in the kinetic chain extend simultaneously. As the legs drive back,
extension at the knees, and torso in an upright position, shoulders are locked
over the hips. The accumulation of forces generated around each joint, results
in an overall production of force. A push-like pattern can be used to improve
force production and accuracy (Magias, T 2016).
Kinetic energy is supported during the drive phase, and is lost during
the recovery phase. The average kinetic energy of rowers is much higher than
that of the boats energy. The gain of energy during the drive phase is much
higher for the rower, compared to the boat. The rower accumulates 82-90% of the
systems kinetic energy, compared to the boat which acquires 10-18%. During the
recovery phase, the boat shell receives nearly the same amount of energy from
that of the rower during the drive phase. This exchange of energy however, between
the boat and the rower, does not affect acceleration of the whole system
(Kleshnev, V., 2002). During the catch phase, the rower’s acceleration is
higher than the acceleration of the boat itself and therefore uses the kinetic
energy of the boat shell. This stops their recovery movement and allows their
body mass to accelerate before the rower places the blade into the water. Rowers
apply more ‘net propulsive force’ to the boat shell whilst at the same time,
accelerating their body mass significantly increasing the speed of the whole
rowers-boat system (Kleshnev, V. 2002).
Injury Prevention:
As clearly listed in figure 1. Rowing is a physically demanding sport on
all aspects of the human body. This requires maximal body effort and proper
flexibility. Due to the physiological demands on the muscular system, in order
to prevent injury, appropriate strength conditioning and cardiovascular
training programs in conjunction with a rowing regime will help to improve
performance, decrease injury and aid in recovery (Rumball, Lebrun, Di Ciacca
& Orlando, 2005 & Athletes Equation, 2014).
Due to excessive hyper flexion and twisting, the most frequently injured
region is the low back. This can result in specific injuries such as
spondylolysis, sacroiliac joint dysfunction and disc herniation (Rumball,
Lebrun, Di Ciacca & Orlando, 2005). In order to strengthen the lower back,
various strengthening workouts can be implemented. Exercises such as: hang
power cleans, front squats, deadlifts, Romanian deadlifts (see figure 4), bent
over rows and Russian twists should be considered to maximise back and core
strength (Athletes Equation, 2014).
Figure 4:
Conclusion:
The information as discussed allows an insight to the biomechanics
involved with the rowing stroke in order to achieve optimal, efficient
technique. In conclusion, in order to achieve this, the key elements of:
techniques and sequence, newtons three laws of motion, impulse momentum
relationship and momentum, torque and centre of mass, angular kinetics, work,
power and energy, gravity, buoyancy, drag and propulsion and kinetic energy
must all be considered and understood. As rowing is one of the most physically
demanding sports, sufficient training must too be considered in order to
maximise results and enhance performance.
References:
· Athletes Equation. (2014).
Strength Training for Rowers. Athletes Equation: The Solution for Elite
Performance. Retrieved from: http://athletesequation.com/strength-training-for-rowers/
· Baudouin, A., & Hawkins, D. (2002). A biomechanical
review of factors affecting rowing performance. British journal of sports medicine, 36(6), 396-402.
· Blazevich, A. (2010).
Sports Biomechanics, the basics:
Optimising human performance. A&C Black.
· Caplan, N., & Gardner, T. (2007). A mathematical model of
the oar blade–water interaction in rowing. Journal
of sports sciences, 25(9),
1025-1034.
· Ferguson, A.
(2016). Rowing techniques for coaches: catch, drive, release and recovery. ACT
Rowing Association. Retrieved from: http://rowingact.org.au/former%20website/SDO/TECHNIQUE_1.html
· Kleshnev, V.
(2010). Biomechanics for rowing technique and rigging. Bio Row. Retrieved from: http://www.veslo.cz/odborne-texty-ke-stazeni/5639914/Biomechanics_for_Rowing_technique_and_rigging_by_V._Kleshnev.pdf
· Kleshnev, V. (2002). Moving the rowers: Biomechanical
background.Australian Rowing, Carine, WA, 25, 16-19.
· Korner, T. (2016). A comparative analysis of GDR and Adam
Styles, accessed on 16/06/2016, from World Rowing: http://www.worldrowing.com/uploads/files/3Chapter2.pdf.
· Kuehn, K. (2015). Newton’s Laws of Motion. In A Student's Guide Through the Great
Physics Texts (pp. 261-264).
Springer New York.
· Magias, T. (2016). Workshop-
Impulse- momentum relationships in Physical Education, in HLPE3531 workshop, on
May 26th 2016, Flinders University, Bedford Park, SA.
· Magias, T. (2016).
Workshop- Energy, work, efficiency, in HLPE3531 workshop, on June 9th 2016,
Flinders University, Bedford Park, SA.
· New South Wales. (2016).
New South Wales Union of Rowers-
Competitive Rowing Boat Types, accessed on 16/06/2016, from http://www.nswrowers.com/boats.html.
· Nolte, V. (n.d.)
Introduction to the biomechanics of rowing. FISA
Coaching Development Programme Course - Level III. Retrieved from: http://www.worldrowing.com/uploads/files/3Chapter3.pdf
·
Rumball,
J. S., Lebrun, C. M., Di Ciacca, S. R., & Orlando, K. (2005). Rowing
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