 Effect of the limited
interchange rule on players leaving the field at an NRL club
Click
to read the .pdf version The aim of this study was
to compare occasions where players left the field due to injury at a National
Rugby League (NRL) club before and after a change to the of the limited
interchange rule (from 1.9 to 1.2 players per team per game). interchange rule.
There were 141 games assessed under unlimited interchange and 94 games after the
introduction of the rule limiting teams to 12 interchanges per game. There was a
significant reduction in the rate of players leaving the field due to injury
after the institution Facial injuries, such as broken noses and lacerations,
were the injury categories most responsible for the reduction in players leaving
the field. The rate of players leaving the field through injury and being unable
to return was essentially unchanged (0.76 to 0.86 players per team per game).
There was no occasion under the new rule where a player was injured after all 12
interchange replacements had been used, which would have forced the team to
either play with one less player or keep a player on the field against medical
advice. There were also no occasions in any game where more than 4 players were
injured and unable to return, forcing the team to play ‘a man short’.
However on 3 occasions (twice under the old rule and once under the new rule), 4
players sustained an injury which prevented them from returning and therefore no
further interchanges were possible after the fourth player became unfit to
return. The new rule has resulted in a significant decrease in the number of
players leaving the field with a minor upper body injury to be ‘checked’ by
the medical staff. This consequence does theoretically increase the risk that a
player may continue to play with a serious upper body injury without being
assessed by the medical staff. Old rule (1998-2000) = Unlimited interchange between players New rule (2001-2002) = Limited interchange = maximum of 12 movements per team per game between the field and the interchange bench Introduction
The limited interchange
rule includes the provision that if a player needs to leave the field after 12
interchanges have been used then his team must play with a man short for the
time he is off the field. The only exception to a team being charged for an
interchange movement under the new rule is where a player is injured directly as
a result of illegal play by the opposition. In this circumstance, the referee
signals to the interchange steward that the player may be replaced without
charging an interchange movement to his team. It is notable that on occasions
where a referee forces a player to leave the field because of uncontrolled
bleeding (unless this was directly caused by illegal play), that the team must
either surrender an interchange to replace him or play with one less player
until he can return. The aim of this study was
to compare occasions where players left the field due to injury at an NRL club
before and after the change to the interchange rule, to assess the impact that
the rule change has had on the on-field management of injuries. Methods The medical staff at the club recorded all injuries presenting for treatment into an injury database. Included in the database were all occasions of players leaving the field (and being replaced) due to injury or illness and whether the player was subsequently able to return to the field or not. The scope of the study was all games for the club’s two senior grades (National Rugby League and New South Wales Rugby League First Division) over the regular season and finals. There were 141 team games
assessed before and 94 team games after the introduction of the limited
interchange rule. A comparison was made between the rates of players leaving the
field through injury before and after the rule change, and then also the rates
of players leaving the field and being unable to return before and after
the rule change. Results Table 1 and 2 list the
rates of players leaving the field before and after the introduction of the new
interchange rule. In table 1, all instances of players leaving the field are
included. In Table 2, only those instances where a player left the field and was
assessed as unfit to return are included. Table 1 shows that there
was a significant reduction in the rate of players leaving the field due to
injury after the institution of the limited interchange rule (from 1.9 to 1.2
players per team per game). Expressed as a risk reduction, players were 38% less
likely to leave the field due to injury after the institution of the new limited
interchange rule. The specific injuries that
were most responsible for the decrease in players leaving the field through
injury were facial fractures, head and neck lacerations and ‘other’ upper
limb injuries. Table 1
– Comparison of rates of players leaving the field through injury
* Significantly (p<0.5) less players leaving the field injured under
limited interchange # Significantly (p<0.5)
more players leaving the field injured under limited interchange Table 2
– Comparison of rates of players leaving the field through injury who
were unable to return
# Significantly (p<0.5) more players unable to return to field under
limited interchange On the other hand, table 2
shows that the rate of players leaving the field and being unable to return was
very similar for most categories. There was no category of injury that saw a
significant decrease in players being unable to return to the field due to
injury. Shoulder sprains and dislocations were significantly more likely to
prevent a player returning to the field after the institution of the new rule. There was no occasion
under the new rule in this study where all 12 interchange replacements had been
used and an injury forced the team to either play with one less player or keep a
player on the field against medical advice. There were also no occasions under
either rule where more than 4 players were injured and unable to return, forcing
the team to play ‘a man short’. There were two occasions under the old rule
and one under the new rule where 4 players sustained an injury which prevented
them from returning. In these 3 games, no further interchanges were possible
after the fourth player became unfit to return. Discussion
The advent of limited
interchange has led to a significant decrease in players leaving the field due
to injury at one NRL club. However, this decrease has not led to a significant
change in the number of players who are injured and unable to return. That is,
players who under unlimited interchange were coming off the ground to have minor
injuries checked (particularly to the upper body), and are now successfully
staying on the ground. There does not appear to be a major negative effect on
the overall rate of serious injuries due to this rule change. The one injury category
that had a significant increase (p<0.05) subsequent to the rule change is
shoulder sprains and dislocations. It is difficult to assess whether this is
just due to confounding factors or chance or whether the style of the game has
changed in the years subsequent to the rule change leading to a higher rate of
shoulder injury. It is possible that players who are more fatigued under the
current rules are tackling with poorer technique and are therefore more likely
to injury their shoulder. It is also possible that other confounding factors
(including chance) are responsible for the increase at this club over this time
period. The most controversial
aspect of the new rule from a medical viewpoint is the hypothetical situation
where a team has ‘run out of interchanges’ and a player is seriously injured
(e.g. fractured spinal vertebrae) but he does not leave the field as he does not
want to leave his team a player short. Obviously, if this situation occurred
then medical staff would be powerless to properly assess the player. This is
particularly the case under current NRL rules where doctors and physiotherapists
are not allowed to come on to field during play unless called on by the referee.
Coaches have a responsibility under the new system to always keep a spare
interchange available (using a maximum of eleven interchanges voluntarily) in
case of serious injury. A further controversy of
the current NRL rules is the charging of an interchange to a team who replaces a
bleeding player. If a player is required to leave the field by the referee
because of bleeding, teams have the option of not using a replacement. In this
case, medical staff can attempt to arrest the bleeding wound on the sideline
whilst playing with one less player. The data presented in this study shows a
substantial decrease in players leaving the field due to head and facial
lacerations. Under the limited interchange rule the club has more frequently
repaired head and facial lacerations on the sidelines with a staple gun
[3]
, to minimise the time that
the player is unavailable and without necessitating the use of two interchange
movements to substitute the player off and then back on. Until season 2003, the
British Super League, the world’s other major professional rugby league
competition, had an otherwise similar limited interchange rule except that
interchanges did not count where the player was forced to leave the field
through bleeding. The Super League has for 2003 changed its rule to charge
instances of bleeding as per the NRL rule. The argument for the NRL stance and
for the change in Super League is that it was previously alleged in the Super
League competition that on occasions players and trainers deliberately failed to
stop a tired player from bleeding in order to be granted a ‘free’
interchange by the referee for the ‘blood bin’. In Conclusion At the club studied, there
does not appear to have been a negative impact on injury overall from the change
made by the NRL to introduce a ‘limited interchange’ rule. A very similar
number of players were unable to return to the field due to injury in the period
before and after the rule change. However, there has been a marked decrease in
the number of players leaving the field with a minor upper body injury to be
‘checked’ by the medical staff. This documented reluctance of players to
leave the field to have minor injuries checked under the new rule theoretically
increase the risk that in the future on a rare occasion a player may refuse to
leave the field with a serious injury due to the new rule. For correspondence and
further information on NRL injuries, visit www.injuryupdate.com.au References
1.
Gibbs N. Injuries in professional rugby league. A three-year prospective
study of the South Sydney Professional Rugby League Football Club. Am J Sports Med 21(5):
696-700, 1993. 2.
Gissane C, Jennings D, White J, Cumine A. Injury in summer rugby league
football: the experiences of one club.
Br J Sports Med 32(2): 149-52, 1998. 3.
Orchard J. Video illustration of staple gun use to rapidly repair on
field laceration. British
Journal of Sports Medicine, accepted for publication. 4.
Phillips LH, Standen PJ, Batt ME. Effects of seasonal change in rugby
league on the incidence of injury. Br
J Sports Med 32(2): 144-8, 1998.
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