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Training and game loads and injury risk in elite Australian footballers

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  • Gabbett Performance Solutions

Abstract and Figures

Objectives: To examine the relationship between combined training and game loads and injury risk in elite Australian footballers. Design: Prospective cohort study. Methods: Forty-six elite Australian footballers (mean±SD age of 22.2±2.9 y) from one club were involved in a one-season study. Training and game loads (session-RPE multiplied by duration in min) and injuries were recorded each time an athlete exerted an exercise load. Rolling weekly sums and week-to-week changes in load were then modelled against injury data using a logistic regression model. Odds ratios (OR) were reported against a reference group of the lowest training load range. Results: Larger 1 weekly (>1750 AU, OR=2.44-3.38), 2 weekly (>4000 AU, OR=4.74) and previous to current week changes in load (>1250 AU, OR=2.58) significantly related (p<0.05) to a larger injury risk throughout the in-season phase. Players with 2-3 and 4-6 years of experience had a significantly lower injury risk compared to 7+ years players (OR=0.22, OR=0.28) when the previous to current week change in load was more than 1000 AU. No significant relationships were found between all derived load values and injury risk during the pre-season phase. Conclusions: In-season, as the amount of 1-2 weekly load or previous to current week increment in load increases, so does the risk of injury in elite Australian footballers. To reduce the risk of injury, derived training and game load values of weekly loads and previous week-to-week load changes should be individually monitored in elite Australian footballers.
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Journal of Science and Medicine in Sport 16 (2013) 499–503
Contents lists available at ScienceDirect
Journal of Science and Medicine in Sport
journal homepage: www.elsevier.com/locate/jsams
Original Research
Training and game loads and injury risk in elite Australian footballers
Brent Rogalskia,b,, Brian Dawsona,b, Jarryd Heasmanb, Tim J. Gabbettc
aSchool of Sport Science, Exercise and Health, The University of Western Australia, Perth, Australia
bWest Coast Eagles Football Club, Perth, Australia
cSchool of Exercise Science, Australian Catholic University, Brisbane, Australia
article info
Article history:
Received 25 May 2012
Received in revised form 7 December 2012
Accepted 13 December 2012
Keywords:
Injury prevention
Load monitoring
Team sport
Odds ratios
abstract
Objectives: To examine the relationship between combined training and game loads and injury risk in
elite Australian footballers.
Design: Prospective cohort study.
Methods: Forty-six elite Australian footballers (mean ±SD age of 22.2 ±2.9 y) from one club were involved
in a one-season study. Training and game loads (session-RPE multiplied by duration in min) and injuries
were recorded each time an athlete exerted an exercise load. Rolling weekly sums and week-to-week
changes in load were then modelled against injury data using a logistic regression model. Odds ratios
(OR) were reported against a reference group of the lowest training load range.
Results: Larger 1 weekly (>1750 AU, OR= 2.44–3.38), 2 weekly (>4000 AU, OR=4.74) and previous to cur-
rent week changes in load (>1250 AU, OR = 2.58) significantly related (p< 0.05) to a larger injury risk
throughout the in-season phase. Players with 2–3 and 4–6 years of experience had a significantly lower
injury risk compared to 7+ years players (OR = 0.22, OR= 0.28) when the previous to current week change
in load was more than 1000 AU. No significant relationships were found between all derived load values
and injury risk during the pre-season phase.
Conclusions: In-season, as the amount of 1–2 weekly load or previous to current week increment in
load increases, so does the risk of injury in elite Australian footballers. To reduce the risk of injury,
derived training and game load values of weekly loads and previous week-to-week load changes should
be individually monitored in elite Australian footballers.
© 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
1. Introduction
Playing Australian football requires repeated physical contact
and movements involving endurance, speed and acceleration1
over match durations of 100+ min.2Recently, Australian Foot-
ball League (AFL) interchange rates have dramatically increased,
allowing players additional breaks throughout games, possibly
contributing to higher mean game speeds.3With greater player
physical demands,1,4 injury incidence and prevalence rates have
also increased.3During 2010, each AFL club (on average) expe-
rienced 38.6 new injuries, causing a player to miss one or more
games. Overall, player injuries resulted in an average of 153.8
missed games per club.3
Understanding potential mechanisms of sporting injuries is
important to AFL medical and conditioning staff, as they manage
their players to be fit for matches. Training and game overload is
one possible cause of injury, therefore monitoring these loads in
Corresponding author.
E-mail addresses: brent.rogalski@live.com,brentr@westcoasteagles.com.au
(B. Rogalski).
players is important. Measuring training and game loads exerted
by athletes can be done by multiplying session rating of perceived
exertion5(Borg CR10 RPE) and duration (min). Previous studies
have analysed the relationship between load exerted and injury risk
in team sports including sub-elite6and professional rugby league,7
soccer,8basketball9and cricket.10
Gabbett and Domrow6analysed training loads and injuries
of 183 sub-elite rugby league players, finding increases in odds
of injury in pre-season (OR = 2.12, p= 0.01), early competition
(OR = 2.85, p= 0.01) and late competition (OR = 1.50, p= 0.04)
phases, for each increase in a log (150 arbitrary units) of training
load. Orchard et al.10 reported cricket bowlers completing more
than 50 overs in a match had a significantly increased risk (1.77
times) of injury in the next 14–21 days compared to bowlers com-
pleting less than 50 overs. The delayed effect of the load of previous
weeks is important to consider when analysing load and injury
relationships.
Piggott et al.11 analysed the relationship of injury and illness
with weekly training load in 16 AFL players across a 15-week pre-
season training phase. No significant relationships were reported
between injuries or illness and training load across this period.
However, studies using a larger sample and conducted over a longer
1440-2440/$ – see front matter © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.jsams.2012.12.004
500 B. Rogalski et al. / Journal of Science and Medicine in Sport 16 (2013) 499–503
time period may provide a more comprehensive understanding of
the relationship between training load and injury in AFL players.
Each year approximately 4–8 new rookie players are drafted into
AFL clubs, coming primarily from junior competitions and State
leagues. Senior AFL players have significantly more lean body mass
and bone mineral density than State junior players,12 which is likely
a result of physical maturation from previous training and game
loads within the elite system. Greater movement demands in the
AFL compared to State leagues13 further highlights the increased
physical demands required of junior or sub-elite players in making
the transition into the professional AFL game and training environ-
ment. Therefore, exploring the training and game load tolerance
of players with different years of experience at an elite level is
important.
To date, studies of the training load-injury relationship of AFL
players are limited, with the only study performed restricted to
a small sample of AFL players over a pre-season period.11 There-
fore, the aim of the present study was to examine the relationship
between training and game loads and injury risk in AFL players
from a full club squad, across an entire season. Identifying a rela-
tionship between load and injury may allow club staff to make
more objective decisions on when players are at increased risk of
injury.
2. Methods
Elite (n= 46) Australian footballers were involved in this
prospective study. Their mean ±SD age, stature and body mass
were 22.2 ±2.9 years, 187.7 ±7.5 cm and 85.4 ±8.9 kg, respectively.
All were from one AFL club and competed in matches in the AFL
or Western Australian Football League (WAFL) during 2010. The
AFL team played 22 competition matches but did not qualify for
finals. All players provided informed written consent prior to par-
ticipation and all data were obtained anonymously. Ethics approval
was obtained from the Human Research Ethics Committee of The
University of Western Australia.
The 2010 season was split into two main phases to match
the training and game demands required of each period. Dur-
ing pre-season (November to mid-March), players performed 3
field sessions, 3 weights sessions, and several cross training and
running conditioning sessions each week. Late pre-season saw a
gradual reduction in field training loads with the introduction of
pre-season practice games. In-season (mid-March to late-August)
consisted of two weight sessions, one main field training session,
with two lighter field sessions planned around the main session,
followed by a game at the end of the week.
Intensity of training sessions and games were estimated by
each player using the modified Borg CR-10 RPE scale5approx-
imately 30 min following each session. Training and game load
arbitrary units (AU) for each player were then derived by multiply-
ing session-RPE by session/game duration (min). Measurements of
blood lactate concentration and heart rate have correlated strongly
with session-RPE in rugby league6and Australian football14,15
training, suggesting that session-RPE is a valid method for quan-
tifying training loads in team sports.
All injuries were categorised by the club’s physiotherapist and
defined as incidents resulting in a modified training program,
missed training sessions or games. Injuries were classified as being
low severity, resulting in training modification or 1–2 missed train-
ing sessions; moderate severity, where a player was unavailable
for 1–2 games; or high severity, where a player missed 3+ games.
Injuries were also categorised for injury type (description), body
site (injury location) and intrinsic (internal; overuse, overexer-
tion) or extrinsic (external; collision, contact) factors. The club’s
injury definition differs slightly from that of Orchard and Seward’s,3
in that all injuries, including those that limited a player’s capac-
ity to complete training, were taken into account in assessing a
load/injury relationship.
Each day a player was involved in a training session or game,
their previous 1, 2, 3 and 4 weekly individual loads were calcu-
lated. Relationships between training and game loads and injury
were investigated in two ways. Firstly, the likelihood that an accu-
mulation of load could contribute to an injury at a later date was
considered by examining the link between 1, 2, 3 and 4 weekly
cumulative loads and subsequent injury. Secondly, whether a large
increment in load between weeks contributed to an injury was also
explored. This involved analysing week-to-week change between
the current and previous week’s totals. Cumulative and absolute
changes in load are further explained in Supplementary figs. A, B,
C and D (online supplementary data). Load exposure values and
injury data (injury vs. no injury) were then modelled in a logistic
regression analysis. Data were divided into four groups, with the
lowest training and game load range being the reference group.
When an odds ratio (OR) was greater than 1, an increased odds of
injury was reported. Conversely, when an OR was less than 1, a
decreased odds of injury was reported. For an OR to be significant,
95% confidence intervals (CI) would not contain the null OR of 1.00.
Injury incidence was calculated by dividing total number of
injuries by exposure time and reported as rates per 1000 train-
ing and game hours. Chi square analysis compared the frequency
of injuries between pre-season and in-season periods. Differences
in training and game loads between players of different AFL expe-
rience (1, 2–3, 4–6 and 7+ years) were analysed using a one-way
ANOVA and group means compared using a Scheffé post hoc test.
Data were analysed using IBM SPSS Statistics 20.0 and reported as
means and 95% CI. Significance was accepted at p< 0.05.
3. Results
Additional data pertaining to classifications of pre-season and
in-season injuries are provided in (online) Supplementary Table A.
Injury incidence increased (2= 9.37, df = 1, p= 0.002) from
pre-season (21.9 per 1000 h) to in-season (32.8 per 1000 h)
(Supplementary Table B). The thigh (7.3 per 1000 h, 22.2%)
and hip/groin (5.9 per 1000 h, 18.1%) were the most com-
mon sites of injuries in-season, with the most common types
of injuries being muscle strains (10.7 per 1000 h, 32.6%) and
haematomas/contusions (9.3 per 1000 h, 28.5%). Extrinsic injuries
(18.9 per 1000 h, 57.6%) and intrinsic injuries (13.9 per 1000 h,
42.4%) were not different in rate of occurrence in-season.
Average field session loads decreased (p< 0.001) from pre-
season (151 AU) to in-season (97 AU) (Table 1). Game loads
from late pre-season practice matches (642 AU) were signif-
icantly lower (p< 0.001) than in-season competition matches
(912 AU). Similarly, session-RPE intensity measures were lower
in pre-season practice matches (8.5) than in-season competi-
tion matches (8.9), whereas field training intensities were lower
in-season (4.7) compared to pre-season (5.3) sessions. Aver-
age individual weekly loads were greater (p< 0.001) in pre-season
(2027 AU) than in-season (1651AU). Injury incidence in-season
was lowest for 1 year players (28.2 per 1000 h) and highest for
7+ year players (45.4 per 1000 h), however, no significant dif-
ferences between groups were found (Table 1). Players with 7+
years of AFL experience completed significantly (p< 0.01) less load
(29,371 AU) in-season, compared to 2–3 (40,788 AU) and 4–6
year (40,238 AU) players.
Players who exerted 1 weekly loads in-season of >1750 AU were
at significantly higher risk of injury compared to the reference
group of <1250 AU (OR =2.44, 95% CI 1.28–4.66, p= 0.007) (Table 2).
Similarly, players who had completed a 2 weekly load in-season
B. Rogalski et al. / Journal of Science and Medicine in Sport 16 (2013) 499–503 501
Table 1
Load type per session for season phases, total training and game loads (arbitrary units) and injury incidence for different years of AFL experience. Data are mean (95%
Confidence Intervals).
Pre-season In-season Whole-season
Playing experience (y) Injury incidence (per 1000 h)
1 year (n= 7) 12.4 (0.0–27.8) 28.2 (17.3–39.1) 22.0 (15.1–28.8)
2–3 years (n= 15) 23.3 (13.9–32.7) 34.6 (24.2–44.9) 28.7 (21.8–35.6)
4–6 years (n= 13) 24.8 (13.9–35.8) 33.9 (22.9–45.0) 29.2 (19.9–38.5)
7+ years (n= 11) 25.4 (8.3–42.6) 45.4 (7.7–83.1) 31.8 (11.2–52.3)
Training and game load (sum)
1 year 23,475 (20,811–26,140)*35,212 (32,201–38,223) 58,688 (53,399–63,976)
2–3 years 40,986 (38,541–43,430) 40,788 (37,705–43,872) 81,774 (76,693–86,855)
4–6 years 38,303 (34,714–41,891) 40,238 (37,603–42,873) 78,540 (73,522–83,559)
7+ years 33,611 (30,309–36,914)** 29,371 (23,764–34,978)62,982 (54,866–71,098)
Load type Mean load per session
Cross training 294 (286–301)a241 (231–250) 276 (270–282)
Field 151 (147–155)a97 (94–100) 125 (122–128)
Game 642 (612–617) 912 (898–925)b856 (842–871)
Running conditioning 113 (110–117) 111 (104–117) 113 (110–116)
Weights 268 (266–271)a231 (229–233) 250 (248–252)
Note: No significant differences were found between injury incidence in AFL years experience groups.
*1 year (p< 0.001) significantly lower than 2–3, 4–6 and 7+ years.
** 7+ years (p< 0.01) significantly lower than 2–3 years.
7+ years (p< 0.01) significantly lower than 2–3 and 4–6 years.
1 year and 7+ years (p< 0.01) significantly lower than 2–3 and 4–6 years.
aPre-season (p< 0.001) significantly greater load than in-season.
bIn-season (p< 0.001) significantly greater load than pre-season.
of >4000 AU were at significantly higher risk of injury compared
to the reference group of <2000 AU (OR = 4.74, 95% CI 1.14–19.76,
p= 0.033). Injury occurrence in-season was also higher for play-
ers who experienced a previous to current week change in load of
>1250 AU (OR = 2.58, 95% CI 1.43–4.66, p= 0.002) compared to the
reference group of <250 AU.
Players with 2–3 (OR = 0.22, 95% CI 0.07–0.68, p= 0.009) and 4–6
(OR = 0.28, 95% CI 0.10–0.82, p= 0.020) years of AFL experience were
found to have a significantly lower risk of injury compared to 7+
year players when a previous to current week change in load was
>1000 AU (Table 3). Interestingly, 1 year players had a significantly
lower injury risk (OR = 0.39, 95% CI 0.16–0.93, p= 0.035) when com-
pared to the 7+ year reference group when experiencing a 1 week
load of >1650 AU.
Table 2
In-season training and game load risk factors for injury in elite Australian footballers.
Load calculation In-season
OR 95% CI p-Value
Exp(B) Lower Upper Sign.
Cumulative load (sum)
1 week
<1250 AU (reference) 1.00
1250 AU to <1750 AU 1.95 0.98 3.85 0.056
1750 AU to <2250 AU 2.44 1.28 4.66 0.007
>2250 AU 3.38 1.69 6.75 0.001
2 weeks
<2000 AU (reference) 1.00
2000 AU to <3000 AU 2.98 0.70 12.66 0.138
3000 AU to <4000 AU 4.03 0.98 16.53 0.053
>4000 AU 4.74 1.14 19.76 0.033
Absolute change (±)
Previous to current week
<250 AU (reference) 1.00
250 AU to <750 AU 1.34 0.90 2.01 0.148
750 AU to <1250 AU 0.89 0.50 1.58 0.680
>1250 AU 2.58 1.43 4.66 0.002
Note: No significant odds ratios were calculated in the pre-season phase.
OR, odds ratio; CI, confidence intervals.
4. Discussion
The purpose of this study was to examine whether a relationship
existed between training and game loads and injury in AFL players.
These results indicate injury risk is significantly higher for players
who exert larger 1 (>1750 AU) and 2 weekly loads (>4000 AU) or a
large previous to current week increment (>1250 AU) in compari-
son to lower training and game load ranges (<1250 AU, <2000 AU,
<250 AU), respectively. These findings suggest that the training and
game loads of elite Australian football players should be individu-
ally monitored on a weekly basis.
Non-contact and soft tissue intrinsic injuries are considered
largely preventable, whereas contact and collision extrinsic injuries
are considered generally unavoidable.7A range of intrinsic (42.4%)
and extrinsic injuries (57.6%) were found during in-season. The
inclusion of extrinsic injuries within this study is consistent with
previous research6,8 as Gabbett and Jenkins16 reported training and
game loads in professional rugby league to be strongly correlated
Table 3
AFL years experience risk factors for injury above certain training and game load
values.
Load calculation In-season
OR 95% CI p-Value
Exp(B) Lower Upper Sign.
Cumulative load (sum)
1 week
>1650 AU
7+ years (reference) 1.00
1 year 0.39 0.16 0.93 0.035
2–3 years 0.74 0.43 1.25 0.258
4–6 years 0.67 0.38 1.17 0.160
Absolute change (±)
Previous to current week
>1000 AU
7+ years (reference) 1.00
1 year 0.14 0.02 1.13 0.065
2–3 years 0.22 0.07 0.68 0.009
4–6 years 0.28 0.10 0.82 0.020
Note: No significant odds ratios were calculated in the pre-season phase.
OR, odds ratio; CI, confidence intervals.
502 B. Rogalski et al. / Journal of Science and Medicine in Sport 16 (2013) 499–503
with contact injuries (r= 0.80, p< 0.01). However, intrinsic injuries
are thought to be more directly linked with training and game
loads.7A limitation of the injury classification within the present
study was that recurrent or new injuries were not documented.
The risk of injury in-season for elite Australian footballers
increased as the amount of 1 weekly load increased from the
range of 1750 AU to <2250 AU (OR = 2.44) and >2250 AU (OR = 3.38)
when compared to the reference group of <1250 AU. Gabbett and
Domrow6also found significant relationships between 1-weekly
training loads and injury risk in sub-elite rugby league players in
early (OR =2.85) and late (OR = 1.50) in-season periods.
As this study completed a rolling day-by-day analysis of train-
ing and game loads and injuries, it accounted for instances where
two games were played within a 6-day period (e.g. Sunday game
followed by a Saturday game). Injury rates of elite soccer players
who played 2 matches within a week were significantly higher
when compared to players involved in only 1 match.17 Although
this study analysed elite soccer players playing 2 matches within 4-
days, our results suggest that AFL players participating in 2 matches
within 6-days may be at an elevated risk of injury. However, more
specific research on the turnaround time between matches and
injury risk using a larger sample of teams is required.
After recovering from an injury, a player does not always have
sufficient time to gradually increase their week-to-week training
load prior to returning to large game loads. To our knowledge, this is
the first study to highlight the importance of monitoring the week-
to-week change in training and game loads. Players who exerted a
previous to current week change in load of >1250 AU were found to
be 2.58 times more likely to be injured in comparison to the refer-
ence group of <250 AU. Players returning from previous hamstring
injuries have been shown to have a 9% chance of re-injury within
the week of returning to matches.18 A more conservative approach
by gradually increasing the week-to-week training loads of previ-
ously injured AFL players, before large game loads occur, may result
in a reduced chance of re-injury. Potentially, players returning from
injury may benefit by being used as a substitute as a method to limit
their initial game load and reduce injury risk.
During pre-season, no significant relationships between weekly
or week-to-week changes of load and odds of injury were found.
Similarly, no relationships were reported between average weekly
pre-season training load and team injury incidence in elite rugby
league19 and AFL11 players. However, in a study analysing the pre-
season training loads and odds of injury of sub-elite rugby league
players, an increase in log of training load (150 AU) per week was
found to significantly increase the odds of injury (OR = 2.12).6There
is greater perceived control over the load exerted by elite play-
ers during pre-season, as session durations are usually planned
by experienced conditioning staff and intensities are predicted by
selecting activity/drill types (based on session-RPE averages). Play-
ers involved in this study would have had their pre-season training
loads closely monitored and modified, which may have influenced
the insignificant pre-season results found. Furthermore, the spe-
cific details of the training program of the AFL club involved within
the study are currently unavailable for publication, as they are con-
sidered highly confidential.
Musculoskeletal immaturity of 1 year AFL players12 was hypo-
thesised here to cause an increased injury risk per training and
game load, in comparison to 2–3 and 4–6 year players. However, no
significant relationships were found between load derived values
and injury risk. These results differ from a study reporting 1-weekly
training loads to significantly relate to traumatic injuries in elite
youth soccer players.8The in-season loads of the 1 year players
within our study were highly monitored and modified, resulting in
5000 AU lower loads compared to 2–3 and 4–6 year players. Due
to the strict load modification strategy of 1 year players, they were
not exposed to high weekly or week-to-week load changes and
recorded the lowest in-season injury incidence (28.2/1000 h). Con-
sequently, training and game load modification of immature first
year players entering the elite system may be useful for preventing
injuries. Reductions in pre-season training loads in sub-elite rugby
league players have also been found to reduce injury rates.20 The
influence of pre-season training load on in-season injury risk in
elite Australian footballers is an interesting concept which is yet to
be examined.
The best starting 22 AFL players are generally older and
more experienced21 and frequently have accelerated returns from
injury to full training and game loads, in an attempt to enhance
team performance. Consequently, they are generally exposed to
high week-to-week load increments. The 7+ year group had the
largest in-season injury incidence (45.4 per 1000 h) and therefore
completed significantly lower in-season loads (6000–11,000 AU)
compared to the less experienced groups. The injury risk of 2–3
(OR = 0.22) and 4–6 year players (OR= 0.28) was significantly lower
than 7+ year players when experiencing a previous to current week
change in load of >1000 AU. The body’s ability to respond to rapid
force changes or recover from fatigue has been speculated to slowly
diminish as age and experience increases.22 Therefore, care should
be taken when exposing 7+ year players to a large previous to cur-
rent week change in load. A confounding variable in the elevated
odds of injury in more experienced AFL players is possibly previous
injury history, as it has been reported as an independent predictor
of subsequent hamstring injuries.23 Future studies should analyse
multiple seasons of data to more thoroughly investigate the effect
of increasing experience on training and game loads and injury risk
in AFL players.
Minimising injury risk is vitally important in elite team sports,
as low injury rates can be critical to team performance.24 How-
ever, training programs must elicit fitness improvements so that
players are adequately prepared to endure the demands of compet-
itive games. No fitness observations were made to analyse whether
reductions in training load were detrimental to performance. Mon-
itoring of global positioning system information (distance, sprint
and accelerometer loads) and psychological data such as perceived
muscle soreness, fatigue, mood, and sleep ratings,18 may provide
extra insight into injury risk relationships in elite Australian foot-
ballers.
5. Conclusion
During an elite Australian football in-season, larger 1 (>1750 AU)
and 2 weekly loads (>4000 AU) and substantial previous to cur-
rent week change in load (>1250 AU) were found to significantly
increase injury risk when compared to lower training and game
load ranges (<1250 AU, <2000 AU, <250 AU), respectively. As a
method to reduce the risk of injury, derived training and game load
values of weekly loads and previous week-to-week load changes
should be monitored individually in elite Australian footballers.
Practical applications:
The non-invasive and simple session-RPE method is useful for
tracking training and game loads in respect to injury risk in elite
Australian footballers.
Weekly load sums and previous week-to-week changes in load
should be monitored in-season for individual elite Australian
footballers, as they are significantly related to injury risk.
Training and game load modification strategies for first year AFL
players may be important in achieving low injury incidence in
their first season.
Future in-season load management modifications could include
planned reduction in training or game loads (especially by being
the designated substitute, or player subbed out of game).
B. Rogalski et al. / Journal of Science and Medicine in Sport 16 (2013) 499–503 503
Acknowledgement
No external financial support was received for this study.
Appendix A. Supplementary data
Supplementary data associated with this article can be
found, in the online version, at http://dx.doi.org/10.1016/j.jsams.
2012.12.004.
References
[1]. Wisbey B, Montgomery PG, Pyne DB et al. Quantifying movement demands of
AFL football using GPS tracking. J Sci Med Sport 2010; 13(5):531–536.
[2]. Gray AJ, Jenkins DG. Match analysis and the physiological demands of Australian
football. Sports Med 2010; 40(4):347–360.
[3]. Orchard JW, Seward H. Injury report 2010: Australian Football League. Sport
Health 2011; 29(2):15–29.
[4]. Norton KI, Craig NP, Olds TS. The evolution of Australian football. J Sci Med Sport
1999; 2(4):389–404.
[5]. Foster C, Florhaug JA, Franklin J et al. A new approach to monitoring exercise
training. J Strength Cond Res 2001; 15(1):109–115.
[6]. Gabbett TJ, Domrow N. Relationships between training load, injury, and fitness
in sub-elite collision sport athletes. J Sports Sci 2007; 25(13):1507–1519.
[7]. Gabbett TJ. The development and application of an injury prediction model for
noncontact, soft-tissue injuries in elite collision sport athletes. J Strength Cond
Res 2010; 24(10):2593–2603.
[8]. Brink MS, Visscher C, Arends S et al. Monitoring stress and recovery: new insights
for the prevention of injuries and illnesses in elite youth soccer players. Br J Sports
Med 2010; 44(11):809–815.
[9]. Anderson L, Triplett-McBride T, Foster C et al. Impact of training patterns on
incidence of illness and injury during a women’s Collegiate basketball season. J
Strength Cond Res 2003; 17(4):734–738.
[10]. Orchard JW, James T, Portus M et al. Fast bowlers in cricket demonstrate up to
3- to 4-week delay between high workloads and increased risk of injury. Am J
Sports Med 2009; 37(6):1186–1192.
[11]. Piggott B, Newton MJ, McGuigan MR. The relationship between training load
and incidence of injury and illness over a pre-season at an Australian Football
League club. J Aust Strength Cond 2009; 17(3):4–17.
[12]. Veale JP, Pearce AJ, Buttifant D et al. Anthropometric profiling of elite junior
and senior Australian football players. Int J Sports Physiol Perform 2010;
5(4):509–520.
[13]. Brewer C, Dawson B, Heasman J et al. Movement pattern comparisons in elite
(AFL) and sub-elite (WAFL) Australian football games using GPS. J Sci Med Sport
2010; 13(6):618–623.
[14]. Middleton P. Relationship of training intensity measures to player rating of
perceived exertion during Australian rules football training drills [Honours The-
sis (unpublished)]. Perth, The University of Western Australia, 2007.
[15]. Scott TJ, Black C, Quinn J et al. Validity and reliability of the session
RPE method for quantifying training in Australian Football: a com-
parison of the CR10 and CR100 scales. J Strength Cond Res 2012.
http://dx.doi.org/10.1519/JSC.0b013e3182541d2e.
[16]. Gabbett TJ, Jenkins DG. Relationship between training load and injury in profes-
sional rugby league players. J Sci Med Sport 2011; 14(3):204–209.
[17]. Dupont G, Nedelec M, McCall A et al. Effects of 2 soccer matches in a
week on physical performance and injury rate. Am J Sports Med 2010; 38(9):
1752–1758.
[18]. Orchard JW. Recurrent hamstring injury in Australian football. Med Sci Sports
Exerc 1998; 30(5):S52.
[19]. Killen NM, Gabbett TJ, Jenkins DG. Training loads and incidence of injury during
the preseason in professional rugby league players. J Strength Cond Res 2010;
24(8):2079–2084.
[20]. Gabbett TJ. Reductions in pre-season training loads reduce training injury rates
in rugby league players. Br J Sports Med 2004; 38(6):743–749.
[21]. Young WB, Newton RU, Doyle TLA et al. Physiological and anthropometric char-
acteristics of starters and non-starters and playing positions in elite Australian
Rules football: a case study. J Sci Med Sport 2005; 8(3):333–345.
[22]. Maffey L, Emery C. What are the risk factors for groin strain injury in
sport? A systematic review of the literature. Sports Med 2007; 37(10):
881–894.
[23]. Gabbe BJ, Bennell KL, Finch CF et al. Predictors of hamstring injury at the elite
level of Australian football. Scand J Med Sci Sports 2006; 16(1):7–13.
[24]. Eirale C, Tol JL, Farooq A et al. Low injury rate strongly correlates
with team success in Qatari professional football. Br J Sports Med 2012.
http://dx.doi.org/10.1136/bjsports-2012-091040.
... These findings contrast with previous studies in other sports which have found a positive relationship between training load metrics and injury. Regarding elite Australian Footballers, Gabbett [38] found a reduction in absolute training load (sRPE-TL) resulted in a corresponding reduction in injuries, while Rogalski et al. [39] found that an increase in 1-2-week accumulated training load resulted in a higher risk of injury. It is very ...
... These findings contrast with previous studies in other sports which have found a positive relationship between training load metrics and injury. Regarding elite Australian Footballers, Gabbett [38] found a reduction in absolute training load (sRPE-TL) resulted in a corresponding reduction in injuries, while Rogalski et al. [39] found that an increase in 1-2-week accumulated training load resulted in a higher risk of injury. It is very difficult, however, to compare these studies, as not only are the sports vastly different (weight bearing/non-weight bearing), but so too are the weekly training loads, and the statistical analyses make it difficult to compare findings. ...
Article
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Training load monitoring is employed to quantify training demands, to determine individual physiological adaptions and to examine the dose-response relationship, ultimately reducing the likelihood of injury and making a meaningful impact on performance. The purpose of this study is to explore the relationship between training load and injury in competitive swimmers, using the session rate of perceived exertion (sRPE) method. Data were collected using a prospective, longitudinal study design across 104 weeks. Data were collected from 34 athletes centralised in two of Swim Ireland's National Centres. Bayesian mixed effects logistic regression models were used to analyse the relationship between sRPE-TL and medical attention injuries. The average weekly swim volume was 33.5 ± 12.9 km. The weekly total training load (AU) averaged 3838 ± 1616.1. A total of 58 medical attention injury events were recorded. The probability of an association between training load and injury ranged from 70% to 98%; however, evidence for these relationships was deemed weak or highly uncertain. The findings suggest that using a single training load metric in isolation cannot decisively inform when an injury will occur. Instead, coaches should utilise monitoring tools to ensure that the athletes are exposed to an appropriate training load to optimise physiological adaptation. Future research should strive to investigate the relationship between additional risk factors (e.g., wellbeing, lifestyle factors or previous injury history), in combination with training load and injury, in competitive swimmers.
... This is a result of league-wide use of global positioning systems (GPS) to collect data that are used primarily for performance and injury prevention. 20 The match demands of professional AF athletes have been previously established in peer-reviewed literature, 6,7,10,11,13,36,40,50 highlighting the large amounts of highspeed running (HSR) and sprinting completed by athletes. As a byproduct of these advancements, the public has a growing interest in the performance metrics of their favorite athletes. ...
... It is logical that HSR and sprinting should serve as key foci in a preseason program due to the previously reported high in-season demands. 6,7,10,11,13,36,40,50 Typically, athletes who complete higher volumes of training in the preseason are able to cover more distance during in-season match activities. 47 Moreover, a higher session rating of perceived exertion in the late preseason has the biggest influence on performance during the first 4 matches of the season. ...
Article
Background Australian Rules Football athletes complete long preseasons, yet injuries occur frequently at early stages of the competitive season. Little is known about the high-speed running (HSR) prescription during a preseason or whether players are adequately prepared for competition. This study described absolute and relative preseason and in-season HSR demands of 2 professional Australian football teams. Hypothesis HSR and sprinting volumes are significantly lower in elite Australian Rules football athletes during in-season compared with preseason. Study Design Cohort study. Level of Evidence Level 3. Methods During the 2019 season, HSR volume was collected for 2 professional Australian football teams (n = 55). Individual maximum speeds (V max ) were captured to calculate relative running speed thresholds, as reported in 5% increments from 70%V max to 100%V max . Results Weekly volume of running above 70%V max ( P = 0.01; r = 0.56) and 80%V max ( P = 0.01; r = 0.58) was significantly greater in the preseason than the in-season. The weekly volume completed above 90%V max was not significantly greater in the preseason than the in-season ( P = 0.10; r = 0.22). Individual variation in the distance completed at specific percentages of V max expressed as a coefficient of variation was reported as 51% at 71% to 80%V max , 39% at 81% to 90%V max , and 41% at 91% to 100%V max . Conclusion The volume of HSR completed by athletes is far greater in the initial 4 weeks of the preseason than in any other point in preseason or competitive phases. At the individual level, there is substantial variation in the distance covered. This supports the concept of a heavily individualized approach to high-speed prescription and monitoring. Clinical Relevance Practitioners should carefully consider individual variation regarding sprinting volume during both preseason and in-season when prescribing and monitoring training to improve on-field performance and reduce the risk of injury.
... Las características del fútbol llevan a cuantificar la carga interna mediante la percepción subjetiva de esfuerzo de sesión, método sencillo y no invasivo (Rogalski et al., 2013) que presenta correlaciones significativas con indicadores de carga externa, como la distancia recorrida o carga del jugador basado en acelerometría , a pesar de que no diferencia trabajos cortos de alta intensidad y trabajos longevos de baja intensidad (Soligard et al., 2016). Asimismo, la invasión tecnológica hace que la tecnología Global Positioning System (GPS) sea la más utilizada en el control de carga externa, puesto permite conocer el perfil físico de una manera fiable y válida y se considera más relevante en el contexto de reducir el riesgo de lesión (Buchheit, 2016), aunque también falta información y estudios que corroboren los algoritmos de carga del jugador (Scott et al., 2013). ...
... El control de carga conduce a que las lesiones por sobreuso o no contacto se consideren altamente predecibles y evitables (Rogalski et al., 2013), pero no se puede interpretar la relación carga de trabajo-lesión de manera aislada (Malone et al., 2018), limitarse a un número sería un error (Buchheit, 2016). La lesión presenta etiología multifactorial a diferentes escalas temporales, desde los constreñimientos personales, asociados a características individuales (fisiología, morfología, psicología), hasta los constreñimientos externos al sistema (clima, terreno, rival…) (Pol et al., 2018). ...
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Abstract: The objectives of the present study were (a) validate a tool to control the workload for a semiprofessional football team and (b) create a drill classification according to external load. A descriptive, observational and prospective study was carried out for 177 sessions of a team of the Spanish First Division U-19. The assessment tools were rate of perceived exertion (RPE 1:10) and accelerometry (Polar Team Pro ®) were recorded per session. External load and drills classification were related and two General Linear Model were proposed. Significant load management relationships between workload parameter and: specificity, exposition and RPE (p < 0,001) were observed. The General Linear Model proposed for the quantification of the external load relates to the proposed classification NA_v3 (R 2 = 0,87; p < 0,001). Finally, the results suggest the possibility of having an objective and valid tool for load management, without the need to have external load registration.
... Training is often associated with injuries in sports, with the relationship between training practices and injury risk being a key focus in sports science (Gabbett, 2010;Rogalski et al., 2013). The intensity and volume of training sessions and methods and the periodization of training play pivotal roles in influencing injury susceptibility (Hurley, 2016). ...
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Sports injuries pose significant challenges in athlete welfare and team dynamics, particularly in high-intensity sports like soccer. This study used machine learning algorithms to assess non-contact injury risk in professional male soccer players from physiological and mechanical load variables. Twenty-five professional male soccer players with a first-time, non-contact muscle injury were included in this study. Recordings of external load (speed, distance, and acceleration/deceleration data) and internal load (heart rate) were obtained during all training sessions and official matches over a 4-year period. Machine learning model training and evaluation features were calculated for each of nine different metrics for a 28-day period prior to the injury and an equal-length baseline epoch. The acute surge in the values of each workload metric was quantified by the deviation of maximum values from the average, while the variations of cumulative workload over the last four weeks preceding injury were also calculated. Seven features were selected by the model as prominent estimators of injury incidence. Three of the features concerned acute load deviations (number of sprints, training load score-incorporating heart rate and muscle load-and time of heart rate at the 90-100% of maximum). The four cumulative load features were (total distance , high speed and sprint running distance and training load score). The accuracy of the muscle injury risk assessment model was 0.78, with a sensitivity of 0.73 and specificity of 0.85. Our model achieved high performance in injury risk detection using a limited number of training load variables. The inclusion, for the first time, of heart rate related variables in an injury risk assessment model highlights the importance of physiological overload as a contributor to muscle injuries in soccer. By identifying the important parameters, coaches may prevent muscle injuries by controlling surges of training load during training and competition .
... These differences in workload management strategies are crucial for coaches and physical trainers to consider, as they can significantly influence the risk of injury and player performance. Previous research has shown that high loads increase the risk of injury (Gabbett, 2016) and that substantial modifications in the doses of microcycle to microcycle training are also a factor to take into account (Malone et al., 2017;Cross et al., 2016;Rogalski et al., 2013;Piggott et al., 2009). The management of this change (%) throughout the preseason by the two teams has also been remarkably different, with changes below 10% by Team2 for most of the variables. ...
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Purpose: the main aim of this study was to quantify and compare the weekly external loads of pre-season in two professional football teams. Methods: GPS devices monitored forty-five players in two teams daily in a five-week pre-season period. The external load measures were: number of sessions, total duration, acceleration load (aLoad), total distance (TD), distance at >21 km·h-1 (TD21), distance at >24 km·h-1 (TD24) and Player-Load® (PL). Results: there were differences in the weekly external load between both teams. Team1 trained 30% more time and training sessions than Team2, so the weekly load for all external load variables was higher except for aLoad and TD21 for W1 (Team2>Team1, p<0.05). These differences between teams were not similar for all weeks, with higher differences in weeks 2, 3, and 4. While Team2 proposed a distribution more stable and progressive in high-speed distances (TD21 and TD24) among weeks, Team1 used the inverted U model. In this line, variations between weeks were lower for Team2 (from -4% to 38%) than for Team1 (from -26% to 1,653%). Conclusions: The study's main conclusion was that in addition to a load management with an inverted U model, more widespread in professional football, a more stable and progressive distribution strategy can be proposed in pre-season in a professional setting. Keywords: GPS, training load, team sports, periodization, monitoring.
... Though the primary goal of coaching staff should be to determine a workload strategy that maximizes benefits while minimizing costs, both strategies of underload and overload increase the risk of injury. Excessive accumulations and significant changes in load, leading to prolonged fatigue status, have been identified as primary risk factors [43]. Conversely, an excessively reduced load can also negatively impact performance by leaving players underprepared for the demands of competition. ...
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This study examined the impact of training load periodization on neuromuscular readiness in elite football players using the Locomotor Efficiency Index (LEI) as a measure of performance optimization. Throughout the 2021/22 and 2022/23 seasons, 106 elite male players (age: 19.5 ± 3.9 years) from an Italian professional football club were monitored using Global Positioning Systems (GPS) external load data. The LEI was derived from a machine learning model, specifically random forest regression, which compared predicted and actual PlayerLoad™ values to evaluate neuromuscular efficiency. Players were categorized by weekly LEI into three readiness states: bad, normal, and good. Analysis focused on the variation in weekly LEI relative to weekly load percentage variation (large decrease, moderate decrease, no variation, moderate increase, large increase), which included total distance, high-speed distance (above 25.2 km/h), and mechanical load, defined as the sum of accelerations and decelerations. Statistical analysis showed significant differences only with variations in total distance and mechanical load. Specifically, reducing weekly loads improved LEI in players in lower readiness states, while maintaining or slightly increasing loads promoted optimal readiness. This approach enables coaches to tailor training prescriptions more effectively, optimizing workload and recovery to sustain player performance throughout a demanding season.
... The 10.8 injuries per 1000 h of participation observed is comparable to previous research in similar sub-elite female AF cohorts (9.6 injuries per 1000 h of participation), and markedly lower than the 27.4 and 42.4 injuries per 1000 h of participation previously reported in elite male 20 and female 16 AF, respectively. It is likely that elite female AF athletes are at a greater risk of injury compared to sub-elite athletes, which is supported by the most recent AFLW injury report (2022), where injury incidence was 23.7 injuries per 1000 h of participation. ...
... 32 Traditional sport has extensively researched how day-to-day psychological and physical demands impact injury risk through the implementation of workload monitoring. [33][34][35][36][37][38][39][40] For example, large increases in acute workload have been associated with increased injury risk, 33 with intensity and duration of load proportionally increasing risk. 35 However, such a model has yet to be substantiated in an occupational setting, in particular firefighting. ...
Article
Objective To determine the impact of emergency call volume on exertion, autonomic activity, and sleep among urban structural firefighters. Methods Thirty-four firefighters wore a wrist-based monitor to track sleep and autonomic parameters and rated their level of perceived exertion (RPE) and subjective sleepiness after a 24-hour shift. Predictive variables included total run time and total run time after 11:59 PM. Results Total run time and sleep duration accounted for RPE and subjective sleepiness; while total run time and total run time after 11:59 PM accounted for sleep durations on-duty. Conclusions The current results suggest emergency call volume is associated with indicators of exertion and sleep. As such, call volume tracking is an important consideration for departments to ensure personnel readiness and wellness and provide a method of tracking the occupational demands experienced by firefighters on-duty.
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Objective This study reviewed the current state of machine learning (ML) research for the prediction of sports-related injuries. It aimed to chart the various approaches used and assess their efficacy, considering factors such as data heterogeneity, model specificity and contextual factors when developing predictive models. Design Scoping review. Data sources PubMed, EMBASE, SportDiscus and IEEEXplore. Results In total, 1241 studies were identified, 58 full texts were screened, and 38 relevant studies were reviewed and charted. Football (soccer) was the most commonly investigated sport. Area under the curve (AUC) was the most common means of model evaluation; it was reported in 71% of studies. In 60% of studies, tree-based solutions provided the highest statistical predictive performance. Random Forest and Extreme Gradient Boosting (XGBoost) were found to provide the highest performance for injury risk prediction. Logistic regression outperformed ML methods in 4 out of 12 studies. Three studies reported model performance of AUC>0.9, yet the clinical relevance is questionable. Conclusions A variety of different ML models have been applied to the prediction of sports-related injuries. While several studies report strong predictive performance, their clinical utility can be limited, with wide prediction windows or broad definitions of injury. The efficacy of ML is hampered by small datasets and numerous methodological heterogeneities (cohort sizes, definition of injury and dependent variables), which were common across the reviewed studies.
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Perceptions of wellness are often used by athletes and coaches to assess adaptive responses to training. The purpose of this research was to describe how players were coping with the demands of elite level Australian football over a competitive season using subjective ratings of physical and psychological wellness and to assess the ecological validity of such a monitoring approach. Twenty seven players completed ratings for nine items (fatigue, general muscle, hamstring, quadriceps, pain/stiffness, power, sleep quality, stress, wellbeing). Players subjectively rated each item as they arrived at the training or competition venue on a 1 - 5 visual analog scale, with 1 representing the positive end of the continuum. A total of 2,583 questionnaires were analysed from completions on 183 days throughout the season (92 ± 24 per player, 103 ± 20 per week; mean ± SD). Descriptive statistics and multi-level modelling were used to understand how player ratings of wellness varied over the season and during the week leading into game day and whether selected player characteristics moderated these relationships. Results indicated that subjective ratings of physical and psychological wellness were sensitive to weekly training manipulations (i.e., improve steadily throughout the week to a game day low, p < 0.001), to periods of unloading during the season (i.e., a week of no competition, p < 0.05) and to individual player characteristics (e.g., muscle strain after a game was poorer in players with high maximum speed, p < 0.01). It is concluded that self-reported player ratings of wellness provide a useful tool for coaches and practitioners to monitor player responses to the rigorous demands of training, competition and life as a professional athlete.
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Background Although the incidence of football injuries should relate to team success there is little empirical evidence. Objective We investigated the relationship between injury incidence and team success in Qatar first-division football clubs. Methods Using a prospective cohort study design, we captured exposure and injuries in Qatar male elite football for a season. Club performance was measured by total league points, ranking, goal scored, goals conceded and number of matches won, drawn or lost. Results Lower injury incidence was strongly correlated with team ranking position (r=0.929, p=0.003), more games won (r=0.883, p=0.008), more goals scored (r=0.893, p=0.007), greater goal difference (r=0.821, p=0.003) and total points (r=0.929, p=0.003). Conclusions Lower incidence rate was strongly correlated with team success. Prevention of injuries may contribute to team success.
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The purpose of this study was to examine and compare the criterion validity and test-retest reliability of the CR10 and CR100 rating of perceived exertion (RPE) scales for team sport athletes that undertake high intensity, intermittent exercise. Twenty one male Australian football (AF) players (age: 19.0 ± 1.8 years, body mass: 83.92 ± 7.88 kg) participated the first part (Part A) of this study which examined the construct validity of the session-RPE (sRPE) method for quantifying training load in AF. Ten male athletes (age: 16.1 ± 0.5 years) participated in the second part of the study (Part B), which compared the test-retest reliability of the CR10 and CR100 RPE scales. In Part A, the validity of the sRPE method was assessed by examining the relationships between sRPE, and objective measures of internal (i.e. heart rate) and external training load (i.e. distance travelled), collected from AF training sessions. Part B of the study assessed the reliability of sRPE through examining the test-retest reliability of sRPE during three different intensities of controlled intermittent running (10 km·hr, 11.5 km·hr and 13 km·hr). Results from Part A demonstrated strong correlations for CR10- and CR100-derived sRPE with measures of internal training load (Banisters TRIMP and Edwards TRIMP) (CR10: r = 0.83 and 0.83, and CR100: r = 0.80 and 0.81, p<0.05). Correlations between sRPE and external training load (Distance, higher speed running and player load) for both the CR10 (r = 0.81, 0.71 and 0.83) and CR100 (r = 0.78, 0.69 and 0.80) were significant (p<0.05). Results from Part B demonstrated poor reliability for both the CR10 (31.9% CV) and CR100 (38.6% CV) RPE scales following short bouts of intermittent running. Collectively, these results suggest both CR10 and CR100 derived sRPE methods have good construct validity for assessing training load in AF. The poor levels of reliability revealed under field testing indicate that the sRPE method may not be sensible to detecting small changes in exercise intensity during brief intermittent running bouts. Despite this limitation, the sRPE remains a valid method to quantify training loads in high intensity, intermittent team sport.
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Although the potential link between running loads and soft-tissue injury is appealing, the evidence supporting or refuting this relationship in high-performance team sport athletes is nonexistent, with all published studies using subjective measures (e.g., ratings of perceived exertion) to quantify training loads. The purpose of this study was to investigate the risk of low-intensity (e.g., walking, jogging, total distances) and high-intensity (e.g., high acceleration and velocity efforts, repeated high-intensity exercise bouts) movement activities on lower body soft-tissue injury in elite team sport athletes. Thirty-four elite rugby league players participated in this study. Global positioning system data and the incidence of lower body soft-tissue injuries were monitored in 117 skill training sessions during the preseason and in-season periods. The frailty model (an extension of the Cox proportional regression model for recurrent events) was applied to calculate the relative risk of injury after controlling for all other training data. The risk of injury was 2.7 (95% confidence interval 1.2-6.5) times higher when very high-velocity running (i.e., sprinting) exceeded 9 m per session. Greater distances covered in mild, moderate, and maximum accelerations and low- and very low-intensity movement velocities were associated with a reduced risk of injury. These results demonstrate that greater amounts of very high-velocity running (i.e., sprinting) are associated with an increased risk of lower body soft-tissue injury, whereas distances covered at low and moderate speeds offer a protective effect against soft-tissue injury. From an injury prevention perspective, these findings provide empirical support for restricting the amount of sprinting performed in preparation for elite team sport competition. However, coaches should also consider the consequences of reducing training loads on the development of physical qualities and playing performance.
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There has been no previous investigation of the concurrent validity and reliability of the current 5 Hz global positioning system (GPS) to assess sprinting speed or the reliability of integrated GPS-accelerometer technology. In the present study, we wished to determine: (1) the concurrent validity and reliability of a GPS and timing gates to measure sprinting speed or distance, and (2) the reliability of proper accelerations recorded via GPS-accelerometer integration. Nineteen elite youth rugby league players performed two over-ground sprints and were simultaneously assessed using GPS and timing gates. The GPS measurements systematically underestimated both distance and timing gate speed. The GPS measurements were reliable for all variables of distance and speed (coefficient of variation [CV] = 1.62% to 2.3%), particularly peak speed (95% limits of agreement [LOA] = 0.00 ± 0.8 km · h(-1); CV = 0.78%). Timing gates were more reliable (CV = 1% to 1.54%) than equivalent GPS measurements. Accelerometer measurements were least reliable (CV = 4.69% to 5.16%), particularly for the frequency of proper accelerations (95% LOA = 1.00 ± 5.43; CV = 14.12%). Timing gates and GPS were found to reliably assess speed and distance, although the validity of the GPS remains questionable. The error found in accelerometer measurements indicates the limits of this device for detecting changes in performance.
Article
Objectives: To examine the usefulness of selected physiological and perceptual measures to monitor fitness, fatigue and running performance during a pre-season, 2-week training camp in eighteen professional Australian Rules Football players (21.9±2.0 years). Design: Observational. Methods: Training load, perceived ratings of wellness (e.g., fatigue, sleep quality) and salivary cortisol were collected daily. Submaximal exercise heart rate (HRex) and a vagal-related heart rate variability index (LnSD1) were also collected at the start of each training session. Yo-Yo Intermittent Recovery level 2 test (Yo-YoIR2, assessed pre-, mid- and post-camp, temperate conditions) and high-speed running distance during standardized drills (HSR, >14.4 km h(-1), 4 times throughout, outdoor) were used as performance measures. Results: There were significant (P<0.001 for all) day-to-day variations in training load (coefficient of variation, CV: 66%), wellness measures (6-18%), HRex (3.3%), LnSD1 (19.0%), but not cortisol (20.0%, P=0.60). While the overall wellness (+0.06, 90% CL (-0.14; 0.02) AU day(-1)) did not change substantially throughout the camp, HRex decreased (-0.51 (-0.58; -0.45)% day(-1)), and cortisol (+0.31 (0.06; 0.57) nmol L(-1)day(-1)), LnSD1 (+0.1 (0.04; 0.06) ms day(-1)), Yo-YoIR2 performance (+23.7 (20.8; 26.6) m day(-1), P<0.001), and HSR (+4.1 (1.5; 6.6) m day(-1), P<0.001) increased. Day-to-day ΔHRex (r=0.80, 90% CL (0.75; 0.85)), ΔLnSD1 (0.51 (r=0.40; 0.62)) and all wellness measures (0.28 (-0.39; -0.17)<r<0.25 (0.14; 0.36)) were related to Δtraining load. There was however no clear relationship between Δcortisol and Δtraining load. ΔYo-YoIR2 was correlated with ΔHRex (r=0.88 (0.84; 0.92)), ΔLnSD1 (r=0.78 (0.67; 0.89)), Δwellness (r=0.58 (0.41; 0.75), but not Δcortisol. ΔHSR was correlated with ΔHRex (r = -0.27 (-0.48; -0.06)) and Δwellness (r=0.65 (0.49; 0.81)), but neither with ΔLnSD1 nor Δcortisol. Conclusions: Training load, HRex and wellness measures are the best simple measures for monitoring training responses to an intensified training camp; cortisol post-exercise and LnSD1 did not show practical efficacy here.
Article
The purpose of this research was to investigate the validity and the reliability of 5-Hz MinimaxX global positioning system (GPS) units measuring athlete movement demands. A team sport simulation circuit (files collected from each unit = 12) and flying 50-m sprints (files collected from each unit = 34) were undertaken, during which the total distance covered; peak speed; player load; the distance covered; time spent and number of efforts performed walking, jogging, running, high-speed running, and sprinting were examined. Movement demands were also separately categorized into low-intensity activity, high-intensity running, and very high-intensity running. The results revealed that GPS was a valid and reliable measure of total distance covered (p > 0.05, percentage typical error of measurement [%TEM] < 5%) and peak speed (p > 0.05, %TEM 5-10%). Further, GPS was found to be a reliable measure of player load (%TEM 4.9%) and the distance covered, time spent, and number of efforts performed at certain velocity zones (%TEM <5% to >10%). The level of GPS error was found to increase along with the velocity of exercise. The findings demonstrated that GPS is capable of measuring movement demands performed at velocities <20 km·h(-1), whereas more caution is to be exercised when analyzing movement demands collected by using GPS velocities >20 km·h(-1).