High chronic training loads and exposure to bouts of maximal velocity running reduce injury risk in elite Gaelic football

Abstract

Objectives:
To examine the relationship between chronic training loads, number of exposures to maximal velocity, the distance covered at maximal velocity, percentage of maximal velocity in training and match-play and subsequent injury risk in elite Gaelic footballers.

Design:
Prospective cohort design.

Methods:
Thirty-seven elite Gaelic footballers from one elite squad were involved in a one-season study. Training and game loads (session-RPE multiplied by duration in min) were recorded in conjunction with external match and training loads (using global positioning system technology) to measure the distance covered at maximal velocity, relative maximal velocity and the number of player exposures to maximal velocity across weekly periods during the season. Lower limb injuries were also recorded. Training load and GPS data were modelled against injury data using logistic regression. Odds ratios (OR) were calculated based on chronic training load status, relative maximal velocity and number of exposures to maximal velocity with these reported against the lowest reference group for these variables.

Results:
Players who produced over 95% maximal velocity on at least one occasion within training environments had lower risk of injury compared to the reference group of 85% maximal velocity on at least one occasion (OR: 0.12, p=0.001). Higher chronic training loads (≥4750AU) allowed players to tolerate increased distances (between 90 to 120m) and exposures to maximal velocity (between 10 to 15 exposures), with these exposures having a protective effect compared to lower exposures (OR: 0.22 p=0.026) and distance (OR=0.23, p=0.055).

Conclusions:
Players who had higher chronic training loads (≥4750AU) tolerated increased distances and exposures to maximal velocity when compared to players exposed to low chronic training loads (≤4750AU). Under- and over-exposure of players to maximal velocity events (represented by a U-shaped curve) increased the risk of injury.

Full text

Journal
of
Science
and
Medicine
in
Sport
20
(2017)
250–254
Contents
lists
available
at
ScienceDirect
Journal
of
Science
and
Medicine
in
Sport
journal
h
om
epa
ge:
www.elsevier.com/locate/jsams
Original
research
High
chronic
training
loads
and
exposure
to
bouts
of
maximal
velocity
running
reduce
injury
risk
in
elite
Gaelic
football
Shane
Malonea,b,∗,
Mark
Roeb,
Dominic
A.
Dorana,
Tim
J.
Gabbettc,
Kieran
Collinsb
aResearch
Institute
for
Sport
and
Exercise
Sciences,
Liverpool
John
Moores
University,
United
Kingdom
bGaelic
Sports
Research
Centre,
Institute
of
Technology
Tallaght,
Ireland
cGabbett
Performance
Solutions,
Australia
a
r
t
i
c
l
e
i
n
f
o
Article
history:
Received
25
April
2016
Received
in
revised
form
13
July
2016
Accepted
2
August
2016
Available
online
10
August
2016
Keywords:
Injury
prevention
Team
sport
Odds
ratios
Maximal
velocity
distance
a
b
s
t
r
a
c
t
Objectives:
To
examine
the
relationship
between
chronic
training
loads,
number
of
exposures
to
maximal
velocity,
the
distance
covered
at
maximal
velocity,
percentage
of
maximal
velocity
in
training
and
match-
play
and
subsequent
injury
risk
in
elite
Gaelic
footballers.
Design:
Prospective
cohort
design.
Methods:
Thirty-seven
elite
Gaelic
footballers
from
one
elite
squad
were
involved
in
a
one-season
study.
Training
and
game
loads
(session-RPE
multiplied
by
duration
in
min)
were
recorded
in
conjunction
with
external
match
and
training
loads
(using
global
positioning
system
technology)
to
measure
the
distance
covered
at
maximal
velocity,
relative
maximal
velocity
and
the
number
of
player
exposures
to
maximal
velocity
across
weekly
periods
during
the
season.
Lower
limb
injuries
were
also
recorded.
Training
load
and
GPS
data
were
modelled
against
injury
data
using
logistic
regression.
Odds
ratios
(OR)
were
calculated
based
on
chronic
training
load
status,
relative
maximal
velocity
and
number
of
exposures
to
maximal
velocity
with
these
reported
against
the
lowest
reference
group
for
these
variables.
Results:
Players
who
produced
over
95%
maximal
velocity
on
at
least
one
occasion
within
training
envi-
ronments
had
lower
risk
of
injury
compared
to
the
reference
group
of
85%
maximal
velocity
on
at
least
one
occasion
(OR:
0.12,
p
=
0.001).
Higher
chronic
training
loads
(≥4750
AU)
allowed
players
to
tolerate
increased
distances
(between
90
to
120
m)
and
exposures
to
maximal
velocity
(between
10
to
15
expo-
sures),
with
these
exposures
having
a
protective
effect
compared
to
lower
exposures
(OR:
0.22
p
=
0.026)
and
distance
(OR
=
0.23,
p
=
0.055).
Conclusions:
Players
who
had
higher
chronic
training
loads
(≥4750
AU)
tolerated
increased
distances
and
exposures
to
maximal
velocity
when
compared
to
players
exposed
to
low
chronic
training
loads
(≤4750
AU).
Under-
and
over-exposure
of
players
to
maximal
velocity
events
(represented
by
a
U-shaped
curve)
increased
the
risk
of
injury.
©
2016
Sports
Medicine
Australia.
Published
by
Elsevier
Ltd.
All
rights
reserved.
1.
Introduction
Training
load
has
been
reported
as
a
modifiable
risk
factor
for
subsequent
injury.1Several
studies
have
investigated
the
influence
of
training
workload
and
injury
risk
in
team
sports.
In
profes-
sional
rugby
union,
players1higher
1-week
(>1245
AU)
and
4-week
cumulative
loads
(>8651
AU)
were
associated
with
a
greater
risk
of
injury.
Furthermore,
Rogalski
et
al.2observed
that
larger
1-
weekly
(>1750
arbitrary
units,
OR
=
2.44–3.38),
2-weekly
(>4000
arbitrary
units,
OR
=
4.74)
and
previous
to
current
week
changes
in
load
(>1250
arbitrary
units,
OR
=
2.58)
were
significantly
related
∗Corresponding
author.
E-mail
address:
shane.malone@mymail.ittdublin.ie
(S.
Malone).
to
greater
injury
risk
throughout
the
in-season
phase
in
elite
Aus-
tralian
rules
football
players.
The
ability
to
produce
high
speeds
is
considered
an
important
quality
for
performance,
with
athletes
shown
to
achieve
85–94%
of
maximal
velocity
during
team
sport
match-play.3Well-developed
high-speed
running
ability
and
maximal
velocity
are
required
of
players
during
competition
in
order
to
beat
opposition
players
to
possession
and
gain
an
advantage
in
attacking
and
defensive
situations.4,5 In
order
to
optimally
prepare
players
for
these
maxi-
mal
velocity
and
high
speed
elements
of
match
play,
players
require
regular
exposure
to
periods
of
high-speed
running
during
training
environments6.
Recent
evidence
suggests
that
lower
limb
injuries
are
associated
with
excessive
high-speed
running
exposure.7,8
Within
elite
rugby
league
and
Australian
football
cohorts,
play-
ers
who
performed
greater
amounts
of
very
high-speed
running
http://dx.doi.org/10.1016/j.jsams.2016.08.005
1440-2440/©
2016
Sports
Medicine
Australia.
Published
by
Elsevier
Ltd.
All
rights
reserved.

S.
Malone
et
al.
/
Journal
of
Science
and
Medicine
in
Sport
20
(2017)
250–254
251
within
training
sessions
were
2.7
and
3.7
times
more
likely
to
sus-
tain
a
non-contact,
soft
tissue
injury
than
players
who
performed
less
very-high
speed
running.8,9 However,
these
studies
failed
to
assess
the
potential
impact
that
chronic
training
load
could
have
on
reducing
the
injury
risk
in
these
players.
Currently
there
is
a
lack
of
understanding
of
the
potential
benefits
of
maximal
velocity
expo-
sures
and
also
the
minimum
dose
required
to
provide
protection
against
injuries.
Recent
evidence
suggests
that
high
chronic
training
loads
can
offer
a
protective
stimulus
for
team
sport
athletes.10,11 Australian
rules
football
players
with
higher
1
week
training
loads
(>3519
AU)
were
at
reduced
risk
of
injury
(OR
=
0.199)
compared
to
players
exposed
to
lower
training
loads
(<3518
AU).12 Additionally
Cross
et
al.1have
reported
a
U-shaped
curve
for
training
load
and
injury
risk
in
elite
rugby
union
players
with
low
and
high
training
loads
increasing
injury
risk,
and
intermediate
loads
reducing
injury
risk.
High
aerobic
fitness
has
been
reported
to
offer
a
protective
effect
against
subsequent
lower
limb
injury
for
team
sport
players.6
Higher
training
loads
may
be
needed
to
provide
the
appropriate
stimulus
for
aerobic
fitness
improvements6with
lower
training
loads
potentially
placing
players
at
increased
risk
due
to
a
lack
of
exposure
to
the
physical
stimulus
required
for
competitive
play.6
Although
greater
amounts
of
high-speed
running
have
been
associated
with
injury
risk,
there
is
evidence
that
players
are
often
required
to
perform
maximal
efforts
over
short
to
moderate
dis-
tances
during
competition
and
training.13,14,15 Training
for
team
sport
ultimately
requires
a
balance
between
appropriately
pre-
scribed
training
loads
to
develop
the
required
physical
qualities
to
compete
while
also
allowing
the
appropriate
recovery
between
sessions
and
match-play
to
minimise
injury
risk
for
players.
Given
the
need
for
players
to
perform
maximal
efforts
during
match-play,
exposure
of
players
to
these
maximal
efforts
during
training
may
offer
a
“vaccine”
against
soft-tissue
injury.6However,
the
inter-
relationship
among
these
training
variables
and
potential
injury
risk
is
poorly
understood.
Therefore
the
aim
of
the
current
inves-
tigation
was
to
examine
exposure
to
maximal
velocity
events
as
a
potential
modifiable
risk
factor
for
injury
within
Gaelic
football.
Additionally
with
higher
chronic
training
loads
offering
a
protective
effect
from
injury
in
other
sports,
there
is
a
need
to
investigate
the
interaction
of
chronic
training
loads,
maximal
velocity
exposure,
and
injury
risk
within
Gaelic
football.
Accordingly,
we
explored
the
relationship
between
training
load,
the
number
of
maximal
veloc-
ity
exposures
during
training
and
match-play,
the
distance
covered
at
maximal
velocity
and
injury
risk
in
elite
Gaelic
football
players.
2.
Methods
The
current
investigation
was
a
prospective
cohort
study
of
elite
Gaelic
football
players
competing
at
the
highest
level
of
competi-
tion
in
Gaelic
football
(National
League
Division
1
and
All-Ireland
Championship).
Data
were
collected
for
37
players
(Mean
±
SD,
age:
24
±
3
years;
height:
179
±
5
cm;
mass:
79
±
7
kg)
over
one
season.
The
study
was
approved
by
the
local
institute’s
research
ethics
committee
and
written
informed
consent
was
obtained
from
each
participant.
The
intensity
of
all
competitive
match-play
and
training
pitch
based
sessions
(including
recovery
and
rehabilitation
sessions)
were
estimated
using
the
modified
Borg
CR-10
rate
of
perceived
exertion
(RPE)
scale,
with
ratings
obtained
from
each
individual
player
within
30
min
of
completing
the
match
or
training
session.16
Each
player
was
asked
to
report
their
RPE
for
each
session
confiden-
tially
without
knowledge
of
other
players’
ratings.
Each
individual
player’s
session
RPE
in
arbitrary
units
(AU)
was
then
derived
by
multiplying
RPE
and
session
duration
(min).16 Session-RPE
(sRPE)
has
previously
been
shown
to
be
a
valid
method
for
estimat-
ing
exercise
intensity.17 sRPE
was
then
used
to
calculate
4-week
chronic
workload
(i.e.,
4-week
average
acute
workload).18,19
Maximal
velocity
running
and
exposure
to
maximal
velocity
during
all
sessions
was
monitored
using
global
positioning
system
(GPS)
technology
(VXSport,
Lower
Hutt,
New
Zealand)
providing
data
at
4-Hz.
Players
were
assigned
individual
units
that
were
worn
across
all
sessions
to
account
for
any
inter-unit
variability.
Initially
players’
individual
maximal
velocity
was
assessed
during
a
max-
imal
velocity
test.
During
the
test,
dual
beam
electronic
timing
gates
were
placed
at
0-,
10-,
20-,
30-
and
40-m
(Witty,
Microgate,
Bolzano,
Italy).
Speed
was
measured
to
the
nearest
0.01
s
with
the
fastest
value
obtained
from
3
trials
used
as
the
maximal
velocity
score.
The
calculated
velocity
between
the
20
and
40
m
gates
was
used
as
a
measure
of
maximal
velocity.20 The
intra-class
correlation
coefficient
for
test–retest
reliability
and
typical
error
of
measure-
ment
for
the
10,
20,
30
and
40
m
sprint
tests
were
0.95,
0.97,
0.96
and
0.97
and
1.8,
1.3,
1.3
and
1.2%,
respectively.
Analysis
of
cal-
culated
speeds
revealed
a
significant
correlation
(r
=
0.85,
p
=
0.02)
between
GPS
and
timing
gate
measures,
with
no
significant
differ-
ence
between
speeds
measured
by
the
timing
gates
(31.2
km
h−1)
and
GPS
measures
(31.0
km
h−1)
(p
=
0.842)
therefore
allowing
for
maximal
velocity
to
be
tracked
with
a
high
degree
of
accuracy
with
the
GPS
system.
Maximal
velocity
exposures
were
recorded
when
a
player
covered
any
distance
(m)
at
their
own
individualised
max-
imal
velocity
(km
h−1)
during
training
or
match-play
events.
If
a
player
produced
a
maximum
velocity
in
training
or
match-play
that
exceeded
the
test
value,
this
became
the
players’
new
maxi-
mum
velocity
for
the
period.
During
this
period,
the
players’
ability
to
produce
maximal
velocity
was
also
tracked
in
relative
terms
by
expressing
data
as
a
percentage
of
their
maximal
velocity.
There-
fore
during
this
observational
period,
players’
number
of
maximal
velocity
exposures,
the
distance
covered
at
maximal
velocity
and
their
relative
maximal
velocity
were
tracked
over
weekly
periods
throughout
the
whole
season
in
line
with
the
internal
and
exter-
nal
training
load
measures.
Training
load
(sRPE),
maximal
velocity
distance,
the
number
of
maximal
velocity
exposures
and
the
per-
centage
of
maximal
velocity
achieved
were
then
analysed
across
acute
1-weekly
workload
periods
(Monday–Sunday).
Acute
work-
load
periods
were
compared
to
the
chronic
training
load
over
the
same
period
(previous
4-week
average
acute
workload).19
All
GPS
and
lower
limb
soft
tissue
injuries
were
classified
into
acute
1-weekly
blocks
and
chronic
4-weekly
blocks
using
a
bespoke
database.
Data
were
collected
from
95
pitch
based
training
sessions
from
November
through
September.
Each
player
participated
in
2–3
pitch
based
training
sessions
depending
on
the
week
of
the
sea-
son.
The
pitch
based
training
sessions
were
supplemented
by
2
gym
based,
strength
training
sessions.
The
duration
of
the
pitch
based
training
sessions
was
typically
between
60
and
130
min
depending
on
session
goals.
All
injuries
that
prevented
a
player
from
taking
full
part
in
all
training
and
match-play
activities
typically
planned
for
that
day,
and
prevented
participation
for
a
period
greater
than
24
h
were
recorded.
The
current
definition
of
injury
mirrors
that
employed
by
Brooks
et
al.21 and
conforms
to
the
consensus
time
loss
injury
definitions
proposed
for
team
sport
athletes.22,23 All
injuries
were
further
classified
as
being
low
severity
(1–3
missed
training
sessions);
moderate
severity
(player
was
unavailable
for
1–2
weeks);
or
high
severity
(player
missed
3
or
more
weeks).
Injuries
were
also
categorised
for
injury
type
(description),
body
site
(injury
location)
and
mechanism.2
SPSS
Version
22.0
(IBM
Corporation,
New
York,
USA)
and
R
(version
2.12.1)
software
were
used
to
analyze
the
data.
Descrip-
tive
statistics
were
expressed
as
means
±
SD
and
95%
confidence
intervals
of
maximal
velocity
running
loads
and
the
number
of
maximal
velocity
exposures
during
the
season.
Injury
incidence
was
calculated
by
dividing
the
total
number
of
injuries
by
the
total

252
S.
Malone
et
al.
/
Journal
of
Science
and
Medicine
in
Sport
20
(2017)
250–254
number
of
training
hours
and
match
hours.
These
hours
were
then
expressed
as
a
rate
per
1000
h.
The
95%
confidence
intervals
(CIs)
were
calculated
using
the
Poisson
distribution,
and
the
level
of
significance
was
set
at
p
≤
0.05.
Maximal
velocity
exposure
values
and
injury
data
(injury
vs.
no
injury)
were
then
modelled
using
a
logistic
regression
analysis
with
adjustment
for
intra-player
cluster
effects.
Data
were
initially
split
into
quartiles
(four
even
groups),
with
the
lowest
training
load
range
used
as
the
reference
group.
This
was
completed
for
relative
maximal
velocity,
weekly
maxi-
mal
velocity
distance
and
the
total
number
of
maximal
velocity
exposures.
Additionally,
to
better
understand
the
impact
of
pre-
vious
chronic
training
load
on
maximal
velocity
running,
training
data
was
divided
into
low
(≤4750
AU)
and
high
(≥4750
AU)
chronic
training
load
groups
using
a
dichotomous
median
split.
Maximal
velocity
distance,
maximal
velocity
exposures,
and
injury
data
were
summarised
at
the
completion
of
each
week.
Acute
and
chronic
training
load
were
calculated
as
described
previously.19 Previous
training
load
history
was
then
associated
with
players’
tolerance
to
maximal
velocity
distance,
maximal
velocity
exposures
and
injuries
sustained
in
the
subsequent
week.
Players
who
sustained
an
injury
were
removed
from
analysis
until
they
were
medically
cleared
to
return
to
full
training.
Odds
ratios
(OR)
were
calculated
to
deter-
mine
the
injury
risk
at
a
given
relative
percentage
of
maximal
velocity,
chronic
training
load,
number
of
maximal
velocity
expo-
sures,
and
distance
covered
(m)
at
maximal
velocity.
When
an
OR
was
greater
than
1,
an
increased
risk
of
injury
was
reported
(i.e.,
OR
=
1.50
is
indicative
of
a
50%
increased
risk)
and
vice
versa.
Based
on
a
total
of
91
injuries
from
3515
player-sessions,
the
calculated
statistical
power
to
establish
the
relationship
between
running
loads
and
soft-tissue
injuries
was
85%.
3.
Results
In
total,
91
time-loss
injuries
were
reported
across
the
season
(36
training
injuries
and
55
match
injuries).
A
rate
of
2.4
injuries
per
player
was
observed.
Overall,
match
injury
incidence
was
45.3/1000
h
(95%
CI:
41.9–53.8)
with
a
training
injury
incidence
of
6.9/1000
h
(95%
CI:
5.8–7.8).
The
total
match
and
training
volumes
reported
during
the
season
were
1210
h
and
5975
h
respectively.
Players
who
produced
over
95%
maximal
velocity
within
train-
ing
and
match-play
environments
in
the
preceding
week
had
a
lower
risk
of
injury
than
those
who
produced
lower
maximal
veloc-
ity
(OR:
0.12,
95%
CI
0.01–0.92,
p
=
0.001)
(Table
1).
On
average,
players
were
exposed
to
maximal
velocity
7
±
4
times
during
match
play
and
training
environments;
specifically
players
experienced
4
±
3
exposures
during
training
environments
and
3
±
1
exposures
during
match-play
environments.
When
considered
independent
of
chronic
training
load,
a
higher
risk
of
injury
was
observed
with
both
a
lower
and
higher
number
of
maximal
velocity
exposures
(OR
=
4.74,
95%
CI
1.14–8.76,
p
=
0.023)
(see
Supplementary
Fig.
S1
in
the
online
version
at
doi:
10.1016/j.jsams.2016.08.005).
Table
1
Relative
maximal
velocity
as
a
risk
factor
for
injury
in
elite
Gaelic
football
players.
Data
presented
as
OR
(95%
CI)
when
compared
to
a
reference
group.
External
load
calculation
In-season
OR
95%
Confidence
interval
p-Value
Exp
(B)
Lower
Upper
Relative
maximal
velocity
(%)
≤85%
(Reference)
1.00
Between
85
to
90%
0.72
0.75
2.21
0.336
Between
90
to
95%
0.22
0.10
1.22
0.026
≥95%
0.12
0.01
0.92
0.001
Table
2
Combined
effect
of
chronic
(4
week)
training
load
history
and
exposure
to
maxi-
mal
velocity
events
as
a
risk
factor
for
injury
in
elite
Gaelic
football
players.
Data
presented
as
OR
(95%
CI)
when
compared
to
a
reference
group.
Internal
training
load
In-season
OR
95%
Confidence
interval
p-Value
Exp
(B) Lower
Upper
Maximal
velocity
exposures
Low
chronic
training
load
(≤4750
AU)
≤5
(Reference)
1.00
Between
5
to
10
exposures
1.02
0.83
1.25
0.636
Between
10
to
15
exposures
0.99
0.28
1.22
0.787
≥15
exposures 3.38 1.60
6.75
0.001
Maximal
velocity
exposures
High
chronic
training
load
(≥4750
AU)
≤5
(Reference)
1.00
Between
5
to
10
exposures
0.72
0.75
2.21
0.236
Between
10
to
15
exposures 0.22
0.10
1.22
0.026
≥15
exposures
1.03
0.70
2.62
0.433
Table
3
Combined
effect
of
chronic
(4
week)
training
load
history
and
exposure
to
different
maximal
velocity
distances
as
a
risk
factor
for
injury
in
elite
Gaelic
football
players.
Data
presented
as
OR
(95%
CI)
when
compared
to
a
reference
group.
Internal
training
load
In-season
OR
95%
Confidence
interval
p-Value
Exp
(B) Lower
Upper
Total
weekly
distance
covered
at
maximal
velocity
(m)
Low
chronic
training
load
(≤4750
AU)
<60
m
1.00
Between
60
to
90
m
1.52
1.81
3.90
0.005
Between
90
to
120
m
1.72
0.05
1.11
0.016
Between
120
to
150
m
3.12
1.11
4.99
0.011
High
chronic
training
load
(≥4750
AU)
<60
m
1.00
Between
60
to
90
m
0.12
0.06
1.16
0.035
Between
90
to
120
m
0.23
0.10
1.33
0.055
Between
120
to
150
m
0.26
0.09
1.45
0.056
The
average
session
training
load
was
695
±
136
AU
during
the
study
period,
with
an
average
acute
weekly
training
load
of
3475
±
596
AU.
When
previous
training
load
was
considered,
play-
ers
with
a
higher
chronic
training
load
(≥4750
AU)
were
able
to
tolerate
increased
exposures
to
maximal
velocity
(between
10
to
15
exposures)
events,
with
these
having
a
protective
effect
compared
to
lower
exposures
(OR:
0.22
95%
CI
0.10–1.22
p
=
0.026).
Players
with
a
lower
chronic
training
load
(≤4750
AU)
were
at
increased
injury
risk
(OR:
1.44
95%
CI
1.28–2.22,
p
=
0.107)
when
exposed
to
similar
maximal
velocity
events
(between
10
to
15
exposures)
(Table
2).
The
average
seasonal
1-weekly
running
distance
covered
at
maximal
velocity
was
170
±
69
m.
Players
who
exerted
higher
chronic
training
loads
(≥4750
AU)
were
at
significantly
reduced
risk
of
injury
when
they
covered
1-weekly
maximal
velocity
dis-
tances
of
90
to
120
m
compared
to
the
reference
group
of
<60
m
(OR
=
0.23,
95%
CI
0.10–1.33,
p
=
0.055).
Conversely,
players
who
had
exerted
low
chronic
training
loads
(≤4750
AU)
and
covered
the
same
distance
of
90–120
m
were
at
significantly
higher
risk
of
injury
compared
to
the
reference
group
of
<60
m
(OR
=
1.72,
95%
CI
1.05–2.47,
p
=
0.016)
(Table
3).

S.
Malone
et
al.
/
Journal
of
Science
and
Medicine
in
Sport
20
(2017)
250–254
253
4.
Discussion
The
current
investigation
is
the
first
to
explore
the
relation-
ship
between
training
load,
maximal
velocity
exposures
and
injury
risk
in
elite
Gaelic
football
players.
Our
data
showed
that
when
players’
produced
over
95%
of
their
maximal
velocity
they
were
at
reduced
risk
of
subsequent
injury
(OR:
0.12)
(Table
1).
When
maxi-
mal
velocity
exposures
were
considered
independently
of
training
load
history
a
U-shaped
curve
was
shown
for
number
of
expo-
sures
and
subsequent
injury
risk
(see
Supplementary
Fig.
S1
in
the
online
version
at
doi:
10.1016/j.jsams.2016.08.005).
Interest-
ingly,
the
number
of
exposures
required
to
offer
a
“vaccine”
for
subsequent
injuries
was
related
to
the
previous
chronic
load
per-
formed
by
players.
The
current
investigation
showed
that
a
higher
chronic
training
load
(≥4750
AU)
allows
greater
exposure
to
maxi-
mal
velocity
running
which
in
turn
offers
a
protective
effect
against
injury.
However,
players
with
a
low
chronic
load
(≤
4750
AU)
were
at
increased
injury
risk
at
similar
maximal
velocity
exposures.
Our
data
highlight
that
the
ability
to
expose
players
to
their
maximal
velocity
is
a
function
of
their
chronic
training
load
history
with
maximal
velocity
exposure
protective
for
players
when
combined
with
higher
training
loads.
Practically,
our
data
suggest
that
players
should
be
exposed
to
periods
of
training
that
best
prepare
them
to
attain
higher
velocity
movements.
Our
study
is
the
first
to
investigate
the
impact
of
maximal
veloc-
ity
exposure
on
subsequent
injury
risk
in
an
elite
cohort
of
Gaelic
football
players.
We
observed
that
players
who
produced
≥95%
of
their
maximal
velocity
were
at
reduced
injury
risk
compared
to
players
who
produced
lower
relative
maximal
velocities
(OR:
0.12).
In
addition,
our
findings
suggest
that
players
with
moder-
ate
exposures
to
maximal
velocity
(>6–10)
were
at
reduced
injury
risk
compared
to
players
who
experienced
lower
(<5)
exposures
(OR:
0.24).
Conversely,
players
who
experienced
maximal
veloc-
ity
exposures
of
>10
were
at
a
significantly
higher
risk
of
injury
compared
to
the
reference
group.
The
current
data
suggests
that
moderate
exposure
to
maximal
velocity
running
can
protect
play-
ers
from
subsequent
injury
risk.
Previous
literature
has
supported
the
fact
that
a
moderate
exposure
to
high
intensity
periods
can
offer
a
protective
effect
for
team
sport
players.
Colby
et
al.9high-
lighted
that
players
who
covered
moderate
3-week
sprint
distances
(864–1453
m)
had
lower
injury
risk
compared
to
lower
and
higher
volume
groups.
Our
findings
support
the
exposure
of
players
to
these
maximal
efforts
within
training
situations
to
ensure
they
are
adequately
prepared
for
critical
moments
of
match-play.
We
found
that
players
with
higher
chronic
loads
(≥4750
AU)
experienced
increased
exposures
to
maximal
velocity,
with
this
increase
in
exposure
offering
a
protective
effect
against
injury.
This
might
be
explained
by
these
players
being
exposed
to
previous
training
load
that
improved
their
ability
to
tolerate
subsequent
load,
ultimately
reducing
their
risk
of
injury.
In
con-
trast,
players
with
low
chronic
loads
where
at
greater
risk
of
injury
when
exposed
to
the
same
number
of
maximal
veloc-
ity
exposures,
perhaps
reflecting
the
consequences
of
inadequate
exposure
to
a
sufficient
workload
over
the
previous
period.
Our
results
are
in
line
with
previous
investigations
from
rugby
league
that
have
suggested
that
higher
chronic
loads
protect
against
injury.10 Therefore
coaches
should
consider
that
the
prescrip-
tion
of
training
that
emphasises
reductions
in
training
load
may
actually
increase
athlete’s
susceptibility
to
injury
due
to
inad-
equate
chronic
loads
and
fitness
levels.6,24 However,
coaches
need
to
be
aware
that
high
chronic
workloads,
combined
with
large
spikes
in
acute
workload
have
previously
demonstrated
the
greatest
risk
of
injury
in
team
sport
players10;
this
would
appear
to
be
an
important
consideration
when
increasing
train-
ing
loads
in
order
to
return
players
to
competitive
play.25 Coaches
should
be
aware
that
although
exposure
to
maximal
velocity
has
a
protective
effect,
players
with
higher
chronic
training
loads
are
better
prepared
to
tolerate
subsequent
maximal
velocity
load.
The
current
data
has
shown
that
depending
on
previous
chronic
training
load
status
players
can
tolerate
more
intense
periods
of
training.
Players
with
higher
chronic
training
loads
were
able
to
cover
increased
weekly
distances
(120–150
m)
at
maximal
velocity
with
lower
subsequent
injury
risk
(OR:
0.26).
Interestingly
players
with
lower
chronic
loads
were
at
increased
risk
of
subsequent
injury
(OR:
3.12)
at
the
same
weekly
run-
ning
load
(120–150
m).
The
current
data
provides
information
that
advocates
players
covering
moderate
distance
at
their
indi-
vidual
maximal
velocity.
Coaches
must
be
aware
that
players
need
to
have
the
necessary
physical
qualities
in
order
to
toler-
ate
the
exposures
to
maximal
running
volumes6as
highlighted
by
the
difference
between
low
and
high
chronic
load
groupings.
This
is
supported
by
previous
observations8which
found
that
players
who
covered
more
distance
at
very-high
speed
(>9
m)
suffered
less
time
loss
from
injury
when
compared
to
those
who
covered
less
than
9
m.
Finally,
those
players
who
covered
greater
absolute
distances
at
high-speeds
(>190
m)
missed
fewer
matches
than
players
who
covered
less
distance
at
the
same
thresholds.8
There
are
some
limitations
of
this
study
that
should
be
con-
sidered.
Firstly,
all
conditioning
workloads
(cross-training
and
strength
training)
cannot
be
quantified
through
the
use
of
GPS
technology.
Research
incorporating
these
objective
measures
with
RPE-values
and
other
data
such
as
perceived
muscle
soreness,
fatigue,
mood,
and
sleep
ratings2,26,27 may
provide
additional
insight
into
the
training
load–injury
relationship
of
elite
Gaelic
football
players.
Additionally,
we
acknowledge
that
the
play-
ers’
injury
history
was
not
considered
and
is
recognised
as
an
important
factor
in
subsequent
injury
incidence.6,26 Finally
although
acceptable
validity
and
accuracy
was
reported
for
the
specific
GPS
units
used
within
the
current
study,
it
should
be
noted
that
previous
research
has
questioned
the
accuracy
of
GPS
for
the
measurement
of
high
speed
movements.28 To
reduce
injury
risk
in
Gaelic
football
the
application
of
maxi-
mal
velocity
exposures,
relative
maximal
velocity
and
distance
covered
at
maximal
velocity
should
be
considered
when
moni-
toring
and
modifying
players
weekly
workload
on
an
individual
basis.
5.
Conclusion
In
conclusion
when
maximal
velocity
exposures
were
consid-
ered
independently
of
training
load
history
a
U-shaped
curve
was
shown
for
number
of
exposures
and
subsequent
injury
risk.
Our
data
suggests
that
players
who
produce
≥95%
of
their
maximal
velocity
were
at
reduced
injury
risk
compared
to
players
who
pro-
duced
lower
relative
maximal
velocities.
Coaches
should
expose
players
to
high
percentages
of
maximal
velocity
within
training
sit-
uations
as
this
offers
a
potential
“vaccine”
against
subsequent
soft
tissue
injury.
Players
with
higher
chronic
training
loads
(≥4750
AU)
were
able
to
cover
increased
weekly
distances
(120–150
m)
at
max-
imal
velocity
with
lower
subsequent
injury
risk,
while
players
with
lower
chronic
loads
were
at
increased
risk
of
subsequent
injury
at
the
same
weekly
running
load.
Coaches
should
be
aware
that
play-
ers
need
to
partake
in
hard
but
well
planned
training
to
be
protected
from
subsequent
injury.
Finally,
our
findings
suggest
that
expo-
sure
of
players
to
maximal
velocity
running
should
be
mainstream
practice
in
elite
sport
in
order
to
adequately
prepare
players
for
the
demands
of
competition.
Coaches
should
modify
drills
within
training
to
allow
players
to
be
exposed
to
their
maximal
velocity
or
incorporate
linear
based
running
over
a
distance
that
allows
players
to
attain
these
maximal
velocities
within
the
training
environment.

254
S.
Malone
et
al.
/
Journal
of
Science
and
Medicine
in
Sport
20
(2017)
250–254
Practical
applications
•Exposure
of
players
to
maximal
velocity
running
should
be
main-
stream
practice
in
elite
sport
in
order
to
adequately
prepare
players
for
maximal
velocity
situations
during
match-play.
•Coaches
should
allow
for
situations
within
training
where
play-
ers
can
achieve
high
percentages
of
maximal
velocity
as
these
situations
offer
a
potential
protective
effect
against
injury.
•Players
who
produce
≥95%
of
their
maximal
velocity
are
at
reduced
injury
risk
compared
to
players
who
produced
lower
relative
maximal
velocities.
•Players
with
higher
chronic
training
loads
were
able
to
achieve
greater
exposures
to
maximal
velocity
running
at
reduced
risk.
Therefore,
physically
hard
but
well
planned
training
seems
an
effective
approach
of
preparing
players
for
maximal
velocity
components
of
training.
Acknowledgements
The
authors
would
like
to
acknowledge
with
considerable
gratitude
the
players,
coaches
and
medical
staff
for
their
help
throughout
the
study
period.
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Cross
MJ,
Williams
S,
Trewartha
G
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professional
rugby
union.
Int
J
Sports
Physiol
Perform
2016;
11(3):350–355.
http://dx.doi.org/10.1123/ijspp.2015-0187.
2.
Rogalski
B,
Dawson
B,
Heasman
J
et
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Training
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J
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Med
Sport
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Haddad
Al,
Simpson
BM,
Buchheit
M
et
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