[wdvltalk-social] all you ever need to know about rugby scrums.....

[michael ensor]

Total Impact Method: A Variation on Engagement Technique in the Rugby Scrum

Introduction

The rugby scrum is a formalised technique used to begin play after a minor
infringement. The two forward packs meet, the ball is placed between the two
front rows, and 'hooked' for distribution by the halfback. While this appears to
be a simple technique for restarting the game it has become a major platform of
both attack and defence and in the modern game involves a number of techniques
used to gain an advantage - for both teams.

'crouch and hold '

While there has been considerable discussion (Milburn, 1997: Quarrie, 2001:
Scher, 1982) regarding the frequency of and potential for cervical injury, and
the development of laws to reduce those injuries, the two packs prepare for
contact with every intention of meeting the other team with maximal impact
forces. The command 'crouch and hold' (see fig 1) provides a stationary position
of both packs prior to contact, with the intention of reducing speed, and
corresponding impact forces at engagement. The pack sets up square (or with the
tighthead prop slightly forward to negate screwing of the scrum) to the other
team, and 'holds' until the referee calls 'engage', at which stage the two come
together very quickly. Despite the best intentions of the "Laws of the Game",
each pack drives forward with the intention of beating the other across the
designated centre line of the scrum, and applying maximum impact forces on the
opposition. The advantage of meeting the opposition on their side of the centre
line may be gained by anticipating the referee's call, or moving faster than the
opposition.

Accurate anticipation is difficult, and may cost a penalty. The Total Impact
Method (T.I.M.) utilises basic principles of biomechanics to drive the pack into
engagement more quickly and forcefully than the opposition, and so gains that
advantage legally, and with a number of further benefits.

Before discussing the detailed techniques of T.I.M. however, it is necessary to
revisit the biomechanical principles involved in scrummaging.

Speed/Force Application

The magnitude of force applied by one pack upon the other is proportional to the
mass of the pack, and the rate of change of velocity (acceleration) at impact.
In this case the assumption is made that both packs are of similar mass and that
both have similarly efficient binding techniques. The principle of conservation
of momentum ensures that the pack that is moving faster at impact will apply a
greater force, and that pack will tend to maintain its position rather than
being moved back.

Direction of Force

The direction in which each player applies forces is determined by the body
posture of the player in relation to the point of application (Bartlett, 1999)
and in relation to others. (Quarrie & Wilson, 2000). Body position is influenced
by the placement of the feet, and the efficiency of the binding techniques. For
the purposes of this discussion it is assumed that binding techniques are
satisfactory.

Body Posture: The importance of vertebral column alignment in the transfer of
force from one player to another is well recognised. The phrase "spine in line"
(ACC Rugby Smart, 2001) is commonly used to describe the optimum body position
of players; shoulders and hips at the same height, and head up to transmit
forces through the shoulders at an angle as nearly horizontal as possible. An
essential component of body posture too must be the angles at the hip, knee and
ankle joints, both prior to and during force application. This is a significant
factor in force application technique and will be dealt with in greater detail
in the section on torque-angle relationships.

Foot Position: Track and field athletes, and some international swimmers, choose
to apply forces at the start of their races from an offset foot position, with
one foot in front of the other. While it is obvious that a single leg extension
will not generate as much force as two legs doing the same job, there is ample
evidence (Enoka, 1994) that the extension torque developed in a single leg
vertical jump is greater than the expected 50% of a two legged extension. In
theory then in our scrum there is an advantage in applying forces through one
foot, immediately followed by the other. Certainly from the impulse momentum
point of view the application of force added to the already moving body will
increase the total time of force application, resulting in a greater change in
momentum.

Foot placement however is personal; players may be more comfortable with offset
feet or with feet parallel. It also depends on the particular objective for that
scrum, whether the team is trying to defend an attack or wheel/screw the scrum
to create an advantage. Martin Toomey (personal communication, 2001), fitness
advisor to the All Blacks 1997-1999 says, "In general it is recognised that
having the feet offset allows greater variation when it comes to creating
options as it is difficult to react going backwards with your feet together.

Coaching generally centres around being offset to absorb the impact and then
taking small steps (in unison) to try and promote your scrum".
The greatest force however can be applied with both legs driving in unison, and
in a well-bound scrum, with good coordination, the greatest combined force will
be applied with all players utilising optimal leg forces. At the setting of the
scrum, and in resisting forces, the foot placement from which maximum forces may
be applied might make the difference between moving the opposition and not
moving them. After that first impulse the scrum is almost always in a fluid
situation with the ability to be able to shift feet to alter the direction of,
and absorb impact forces, paramount. However, at the 'set ', in order to drive
forward with maximum force, feet should be close to parallel, at shoulder width,
and turned out slightly to afford a better grip. (see fig 2)

Force Production

The magnitude of the force produced by each player in the pack is determined by
the characteristics of the task itself (Zatsiorsky, 1995). Good coaches and
trainers will have practices and drills that very closely resemble the required
specific scrum activity. The ability of the player to generate maximum forces in
the scrum will be a product not only of their general conditioning and strength
programmes, but of individual anthropometry (Quarrie & Wilson, 2000) and a
specific power development programme designed around the constraints of the
scrum. Our discussion of T.I.M. centres about the mechanical factors that may
influence force production.

Length Tension Relationship: There is a relationship between the length of a
muscle and the force it can produce. The length of single joint muscle is
related to the joint angle, with a muscle at its shortest when the joint is
fully flexed and longest when the joint is fully extended. Tension within the
muscle is at maximum with the muscle at mid-length (Bartlett, 1999) and active
tension is reduced when the muscle is both shortened and lengthened. The
relationship is such that for muscles that cross a single joint the maximum
force is produced near the middle of the range of motion, with lesser forces
produced when the muscle is lengthened or shortened (Zatsiorsky, 1995). The
implication for force production is that it is difficult to generate large
forces with these single joint prime movers, either on your body or an external
object, when the joints are nearing full flexion, or full extension. In our
rugby scrum situation the angles at knee and ankle, and especially the hip,
become an important factor when the application of maximum forces is required.

Force Velocity Relationship: An important aspect of muscle mechanics relates to
the speed with which muscle shortens while active. We refer to the three general
phases of muscle activity as:
      Isometric The muscle length does not change
      ConcentricThe muscle shortens
      EccentricThe muscle is trying to shorten ,but is being forced to lengthen.
      Eccentric muscle activity is common - it occurs whenever we stop a back
      swing prior to throwing a ball, when we walk down stairs or in general,
      whenever we decelerate a body segment.


A muscle can produce a certain amount of force in an isometric situation. If
this muscle then acts concentrically - shortens - the maximum force it can
produce depends on the speed at which it shortens. The faster it is required to
shorten the less force it will develop. The opposite is true for eccentric
muscle action. The faster a muscle is stretched while attempting to shorten, the
larger the forces it can produce. This relationship is referred to as the
force-velocity relationship of muscle and in practice this means that large
forces are not generated when our muscles are shortening at high speeds. (see
fig 3) It is possible, however, to use this relationship to our advantage within
T.I.M. by utilising the eccentric work characteristic. (see Stretch-Shorten
Cycle)

Torque-Angle Relationship/Mechanical Advantage: The most efficient angle of the
joint for the generation of torque varies according to the anatomical structure
of the joint and the point of attachment of the muscles that move that joint.
While individual muscles across a joint may have differing structure and points
of attachment (Enoka 1994), and peak muscle force may not always occur at peak
moment arm (Lieber, 1992), it is safe to say that generally muscle fibres are at
an intermediate length when the joint is approximately mid range. The joint
moment arm is usually maximised at mid range also. Research in both laboratory
and rugby environments (Mills & Robinson, 2000) indicate that maximum forces may
be generated through a mid range of the joint.

It is expected that maximum extensor torque at the hip joint might be generated
through a range 130o to 160o. (Enoka, 1994, Zatsiorsky, 1995). It is interesting
to note that Rodano and Pedotti (1987) report hip angles as acute as 110o
amongst athletes in a scrum. Our flanker in Figure 4 demonstrates an angle of
107o. (In reality he is just about to shift that foot forward.) Quarrie & Wilson
(2000) report that none of the body position variables correlate highly with
individual scrum strength.

The development of maximum knee extension torque occurs through a range
114o-157o (Eloranta & Komi 1980; Enoka, 1994: Zatsiorsky, 1995) and this range
is supported by Mills and Robinson (2000) who in a rugby specific environment
report an optimum knee angle of 120o. (Our prop in Figure 5 demonstrates 110o,
with a strong vertical surface to the lock to push against, and perhaps in
preparation for some movement forward against a live scrum.) In the scrum the
ankle joint will only plantar flex through about 10o (Rodano & Pedotti, 1987),
with maximal force application at 103o (Rodano & Tosoni, 1992).

The optimal direction of force application in the rugby scrum may vary with the
requirements of the specific situation but in simply applying force to the
opposition, Rodano and Tosoni (1992) suggest there is some evidence that in both
applying an impulsive force, and maintaining force application, that an angle of
120o is appropriate. In teaching T.I.M. we have found that, despite the
research, in practice our players tend to adopt a position similar to the back
three in Figure 6. They have settled for something nearer 135o for the lock, and
the No.8 145o.


In summary, we can say that while there is research evidence (Rodano & Pedotti,
1987; Mills & Robinson, 2000) to support the adoption of specific joint angles
in the scrum, there is also a contradictory view (Quarrie & Wilson, 2000) that
suggests that there is a range of joint angles at each of the joints in the leg
through which maximal torque may be generated. These angles are determined by
the implications of the torque-angle and length-tension relationships within
muscle, as well as individual preference and the requirements of the specific
activity.

Bi-articular Muscles: Single joint muscles may be regarded as the prime movers
of the body. They cross a single joint and contraction of the muscle fibres
causes rotation at the joint. However, muscles that pass over two joints, the
"bi-articular" muscles, are just as important as they support an energy transfer
system that in the scrum facilitates the application of force at the ground
delivered from the very powerful single joint extensors of the hip, knee and
ankle.

For all athletes the important bi-articular muscles that support leg extension
are rectus femorus in the quadriceps, biceps femoris in the hamstrings, and
gastrocnemius in the plantar flexors. When the rugby player applies maximum
forces in the scrum, the major activity is leg extension. In crossing two
joints, the origins of each of the three bi-articular muscles move in the same
direction and at the same time as the insertion of the muscle, keeping the
muscle fibres in an almost isometric contraction. This principle of
transmissibility in leg extension transfers work from the single joint hip
extensors - gluteus maximus - all the way through the system to the ground
reaction forces at the ball of the foot.

There is a history of many hundreds of years of research (Galen, 1131-201 A.D;
Fischer, 1927; Lombard, 1903) into the role of the bi-articular muscles in leg
extension, some of it with particular reference to the changing direction of the
forces (Andrews, 1987; Ingen Schenau 1989b). In the scrum situation, with the
player in a spine horizontal position and hip, knee and ankle at an optimum
angle, the reaction force will pass close to the knee, with a small moment arm
(see fig 6) and in front of the hip with a considerably larger moment arm. This
configuration requires activation of the single joint (mono-articular) muscles
at hip and ankle, (gluteus maximus and soleus, and to a lesser extent, vastus at
the knee), combined with a strong activation of the bi-articular hamstrings. The
implication for the player in the scrum is that while general maximal strength
and rate of force development is an essential part of their preparation, special
interest should be taken in the strength characteristics of the hamstring group
to maximise the contribution of the bi-articular system.

The Nervous System: While the central nervous system is of paramount importance
in force production (Zatsiorsky, 1995), there is no evidence that motor unit
activity may be influenced by anything other than specific training, and on
occasions, psychological factors.

Rate of Force Development

It takes time to develop maximal force in a muscle. While the precise time might
vary from person to person, on average, time to peak force will be in excess of
0.4 sec. (Zatsiorsky, 1995). In athletic activity in which speed is of
importance, there is often less time than that available and so there is a trade
off between the two. In the rugby scrum, while there is often little need for
high speed, there will certainly be an advantage gained if peak force can be
reached earlier at engagement. There are two avenues by which we might improve
force production at speed. The first is based upon traditional specific power
training methods (Zatsiorsky, 1995), which in this case would see athletes train
with scrum specific resistance, in scrum posture, and at maximum velocities. The
second avenue is use of the Stretch-Shorten Cycle. (see the following section)

Balance

Traditionally the scrum sets with the front row resisting the force of the locks
as they get into position. To resist this passive force, props will, in most
cases, place the outside foot forward and 'sit back' against the shoulders of
the locks. Regardless of the position of the remainder of the scrum, upon
'engage' the front row must first change the point of balance - usually by
shifting the forward foot back - then attend to the drive forward into the
opposition. The T.I.M. position changes that balance, reducing the time taken to
begin forward motion, and increasing the speed at which the pack moves toward
the opposition.

Stretch-Shorten Cycle

The stretch-shorten cycle (SSC) describes a period in which a muscle undergoes
eccentric work, is stretched, contracts isometrically to stop the counter
movement, and follows immediately with maximal contraction with the intention of
applying a maximal force. The cycle utilises the principles of stretch reflex,
of the length-tension relationship of muscle, storage of elastic energy in the
muscle-tendon complex, enhanced potentiation of muscle, and chemical energy from
the preload effect. Jumpers and gymnasts utilise this concept to enhance jumping
height and it is typified by the stretch involved in the ballistic back swing or
pre-stretch in throwing or racquet games. Research into this phenomenon using
vertical jumping as the vehicle (Komi, et al 1997: van Ingen Schenau, G.J.,
Bobbert, M.F., de Haan, 1997; Winter, 1997;) has indicated that while there is
some disagreement on the actual processes involved, there is increased
activation of muscle. If the major contraction involved takes place within 0.2
secs of the stretch onset, then the combination of all these factors will result
in a higher jump, determined by the velocity at take-off. The same principal
applies in all sporting situations. Increased activation of the muscle fibres by
use of the principles of pre-stretch result in an increase in maximal force
production. Specifically, and importantly for our scrum scenario, force
enhancement occurs in dynamic concentric contractions after stretch, the
force-velocity relationship shifts toward increasing forces at any given
velocity (Bartlett 1999). If the time available for this stretch/shorten action
is less than 0.3sec the rate of force development rather than maximal strength
is the deciding factor (Zatsiorsky 1995).

While the stretch-shorten cycle helps deliver a greater maximal force and
increases the rate of force development, there remains the problem of time. It
seems we may choose between immediate contraction of muscle delivering less
force, or utilisation of the SSC delivering greater force but with a time delay
of up to 0.2sec. In the T.I.M. technique described below there is no deliberate
attempt by players to consciously utilise the SSC. Rather, the set position by
its very construction and the order of force application places players in a
position where there will, in almost every case be a SSC effect.

The Total Impact Method (T.I.M.)

In terms of force application, at the setting of many scrums the Number 8 and
the flankers have been passengers, with head up looking for any last minute
changes by the opposition, and not applying any great force at all in the first
instance. In the T.I.M. technique the Number 8 forward drives it and the major
change the coach must make is to convince the Number 8 to take responsibility
for the drive at engagement. The initial push must be immediate and maximal. In
presenting T.I.M. for use by coaches the assumption is made that players are
well versed and prepared in the techniques of reactive force production, the
adoption of body positions conducive to maximal force production, and binding
techniques adequate to support the activity.

Setting the Scrum

The front row sets in a balanced position bent forward together with spine in
line, head up and slightly higher the hips. Feet are nearly square/parallel,
slightly splayed, and wide enough for a solid base. Weight is on the balls of
feet, and the player is almost falling forward. (see fig 7) The front row is
held in position by the locks; they would fall forward if released.
Locks take their position in the pack with feet in position as for the props,
slightly off-set, and slightly splayed. (see fig 2) From a crouched position,
the head is placed between prop and hooker at hip level, without pushing. The
lock binds with outside arm between the legs of the prop, and onto the shorts
across his inside leg with elbow at approx 900. The inside arm binds across the
back of the companion lock. The locks raise their backside until the back is
horizontal and balance is such that the two are pushing back against the
shoulders of the Number 8. The lock pulls the prop lightly into his shoulder,
treating his backside as if it were eggshell !!

The Number 8 sets with head between the hips of the locks, feet offset as a
sprinter in the blocks, and leaning into and applying some force to the locks.
(see fig 6). The Number 8 binds around the hips rather than between the legs.
The flankers bind onto the lock between the shoulder blades, crouched with feet
offset, and shoulder nestled against the buttocks of the appropriate prop. The
outside foot is forward of the inside foot.

Engagement

Upon the command 'engage,' the Number 8 drives forward with both legs as does a
track sprinter, with extension of the rear leg preceding the front leg
momentarily. This rapid 1-2 action delivers a forward impulse against the
buttocks of the locks, pushing them forward against the front row and initiating
the Stretch-Shorten Cycle in their leg extensors. Simultaneously, the two
flankers do the same, applying a force against the props. The greater this
impulse from the Number 8 the greater will be the SSC effect, with accompanying
increase in rate of force production.

The two locks in response to the forward force applied by the Number 8 are
pushed forward and with a coordinated rapid extension of the legs provide a
propulsive force into the already moving front row, adding to the momentum
initiated by the flankers. If they choose to set with one foot slightly forward
that foot will advance to with the forward movement. All players, but especially
the locks must be practised in the techniques of reactive strength and respond
immediately to the push from behind. The rate of force development in their
extensors is increased by the pre-stretch or loading effect of the preparatory
position, and their drive forward complements the forward motion of the
continuing impulse from the Number 8.

The front row players, being in a slightly forward, off-balance position,
respond immediately to the push from the flankers and with body in optimum
position drive forward, as the force from the locks is added to the impulse.

Note: It is essential during this force application phase that all players must
be aware of the effect of pushing too low on the buttocks of the player in
front. Force applied far from the joint will cause the hip to flex which is
contrary to the required extension.

Contact

The impulse has begun with the Number 8 and as that first force is applied, the
player has brought the back foot forward to place it square with the front foot.
At contact of the two packs all players have both feet on the ground and in
position to provide maximal forces through optimum joint angles. The pack has
moved quickly, and players are in position to maintain that force application,
and resist forces applied by the opposition.

Safety

The greatest fear of every rugby player, coach, administrator and parent is that
of a player suffering a life threatening spinal injury. A player has a greater
chance of suffering such an injury when diving in the recreational swimming pool
or driving to practice (Dedrick, 1985) than when playing. However severe spinal
injuries do occur in rugby amongst all players, and safety must be one of our
considerations.

Coaches and players are competitive and quite consciously seek any available
advantage at scrum time. This advantage is not always in the spirit of the game,
and as demonstrated by the number of penalties, not always within the laws of
the game either. Unfortunately, the traditional head to head construction of the
scrum itself provides a fertile field for prospective neck injury, while also
providing an opportunity for dominance. The desire to dominate and the chance of
injury, do not sit well together. Perhaps the most effective illustration of
this conflict can be found in three quotes below.

Peter Milburn (1993) says, "A majority of injuries are found to occur at
engagement where the forces experienced by front-row playersÉ.can exceed the
structural limits of the cervical spine. These forces are a consequence of the
speed of engagement, and the weight (and number) of players involved in the
scrum."

Ken Quarrie, Injury Prevention Manager of the NZRU,(2001) says, "Players at
higher grades may be at relatively higher risk of injury because of the
increased size and power of players and the greater aggression with which the
game is played."

On the other hand, Graham Henry, coach of the 2001 British and Irish Lions to
Australia, said, "The scrum has become passive in the last two or three years
and I don't think it's good for the game. It's becoming a non-playing part of
the game and it's important we get it sorted before the test series." And, as
reported in the popular press, "It's important that the scrum maintains the
identity it has had over a long history and it doesn't become a part of the game
which is a non entity and embarrassing."

The conflicting points of view demonstrate that coaches and administrators of
the game feel that:

  it is important to do everything in our power to restrict the opportunity for
  cervical spine injuries in the rugby scrum
  any advantage gained is worth the risk.

The discussion that follows addresses those conflicting points of view.

Benefits

Without any doubt the, major attraction of T.I.M. is the advantage gained in
getting to the centre line faster than the opposition, with the accompanying
increased forces. However, the changed stance of players prior to engagement has
also provided some benefits that may well have increased player safety. Coaches
and players in teams using T.I.M. report a number of benefits:

  Increased scrum forces at impact. During the development of T.I.M. amongst
  various teams within the Canterbury (NZ) region, tests were conducted on an
  instrumented scrum machine with a professional pack, and a school 1st XV. In
  both cases, forces applied at impact were significantly greater after T.I.M
  had been learned than before. In addition, coaches and players reported
  increased impact forces, with the ensuing advantage of dominance prior to ball
  entry.

Increased ability to beat the opponent to the line. There is agreement amongst
  coaches and players that a significant aspect of T.I.M. has been the ability
  to beat the opponent to the centre line.

  A more comfortable front row prior to engagement, with the props set without
  having one foot forward to resist the pushing locks. Using T.I.M., the locks,
  rather than pushing forward, are pulling the front row back, which takes any
  pressure off those players and allows them to get well set in a balanced
  stance with head up and spine in line. At this stage, with no forward forces
  to be resisted, the front row may easily adjust hip height and prepare
  themselves for contact with minimal vertical/shear forces. In that 'pulled
  back' position, the heads of opposing forwards are slightly further away from
  each other, reducing the risk of a head clash. (see #7)

  At engagement all feet are on the ground and able to apply/resist maximum
  forces. In practice, the Number 8 utilises a sequential movement with the back
  foot coming forward to be placed parallel the other at contact. Locks in some
  packs have preferred a similar configuration, but the final position at impact
  has been characterised by an increased ability to maintain forces application.
  The position has become known as 16 feet.

  Scrum Unity. Front row players report that using T.I.M. there is a greater
  unity of the pack at contact. With the pack being driven from the back there
  is a bodily contact between players as they drive forward. Upon contact the
  complete mass of the pack is involved in the first contact, making better use
  of the total pack weight. Using previous systems with the front row leading
  the movement toward engagement, the front row makes contact first, followed a
  moment later by the locks coming in from behind.

  Scrum Binding. Using previous methods, it was essential that as the scrum set
  players were tightly bound before engagement. With T.I.M., players reported
  that they may set without the need for very tight binding. At the command
  'engage', the pack moves forward, driven from number 8, and players activate
  their tight binding techniques as they move forward.

  Time available for force development. In retrospect, reduced time was always a
  possibility. With any primary technique change, there must be other changes
  made as a consequence. With T.I.M., the changed posture of the front row has
  resulted in a noted decrease in the separation of the two front rows at
  'crouch and hold'. As the technique developed it was noticed that front row
  players were setting up slightly closer to the scrum machine. With two packs
  using the method, the two front rows have tended to 'set' closer together than
  traditionally. This reduced distance of course has the effect of reducing time
  to contact and may in fact reduce impact forces. Of course, if impact forces
  are in fact reduced, then there may well be a decreased risk of cervical
  trauma at impact.

Conclusion

While the method was developed originally to obtain an advantage in getting over
the centre line of the scrum, there have been benefits in terms of player
control and comfort, with the possibility of increased protection from traumatic
neck injury at engagement. Coaches and players are enthusiastic in their praise
for T.I.M. Players are more comfortable in setting the scrum; there is a greater
speed at engagement, and an increased unity of the pack at impact. Binding
techniques have changed in response to the changed sequence of forces. The scrum
itself seems better able to maintain a forceful position after impact, and the
role of the Number 8 player has changed considerably. These benefits of course
are anecdotal and based on player/coach opinions. We look forward with
anticipation to further research and the practical test of national team
success.

References
AAP: June 22, 2001.
Bartlett, R.M. (1999) Introduction to Sports Biomechanics. E. & F.N.Spon.
London.
Enoka, R. M. (1994) Neuromechanical Basis of Kinesiology. Champaign Ill. Kinetic
Books.
Milburn, P.D. (1989) Mechanics of a Rugby League Scrum. Proceedings of 8th
International Symposium of Biomechanics if Sports. W.E.Morrison ed. Footscray
Institute of Technology, Melbourne, Australia.
Milburn, P.D. (1993) Biomechanics of Rugby Union Scrummaging. Sports Medicine.
16(3) Adis International.
Mills, S.H. and Robinson, P.D. (2000). Assessment of Scrummaging Performance
Using a Pneumatically Controlled Individual Scrum Machine. Proceedings of 18th
International Symposium in Sports. Y.Hong & D. Johns ed. Chinese University of
Hong Kong.
Quarrie, K. (2001) Rugby Union Injuries to the Cervical Spine - A Report to the
New Zealand Rugby Union.
Quarrie K.L. and Wilson B.D., (2000) Force Production in the Rugby Union Scrum.
Journal of Sport Sciences. Vol 18
Robinson, P.D. and Mills, S.H. (2000) Relationship Between Scrummaging Strength
and Standard Field Tests for Power in Rugby. Proceedings of 18th International
Symposium in Sports. Y.Hong & D. Johns ed. Chinese University of Hong Kong.
Rodano, R. and Pedotti, A.(1987) A Qualitative Analysis of Thrust and Motor
Coordination in a Rugby Scrum. Proceedings of First World Congress of Science
and Football. T.Reilly et al ed. 1988. London E.& F.N.Spon.
Rodano, R. and Tosoni, A.(1992) La Mischia nel Rugby. Edir-ermes. Milano.
Rugby Smart. A Guide to Injury Prevention and Peak Performance. N.Z.Rugby Union
and Accident Compensation Corporation.
Scher, A.T., Crashing the Rugby Scrum - an Avoidable Cause of Cervical Spinal
Injury. Case Reports. South African Medical Journal. June 1982 Vol 61(24).
Van Ingen Schenau, G.J. On the Action of Bi-Articular Muscles, A Review.
Netherlands Journal of Zoology 40(3) 521-540 (1990).
Zatsiorski V.M. (1995) Science and Practice of Strength Training. Champaign Ill.
Kinetic Books.

------------------------------------------------------------------------------------------------------

To illustrate, an under 19 (schoolboy) rugby side scrum will generate 9.1kN of force,
so now you know </g>
www.WellingtonLive.co.nz



-- 
No virus found in this outgoing message.
Checked by AVG Free Edition. 
Version: 7.5.485 / Virus Database: 269.13.16/1004 - Release Date: 12/09/07 17:22