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Introduction
A competitive game of professional rugby league is a high-im-
pact collision sport played over approximately 90 min. Like other
football codes, rugby league has been characterized as a high-in-
tensity sport that combines intermittent bouts of very intense
anaerobic exercise interspersed with longer lower-intensity peri-
ods of aerobic exercise. Due to these activity demands, rugby
league players require both a high level of muscular strength
and power combined with a well-developed aerobic capacity.
Additionally, other physiological factors such as increased speed,
speed-endurance, agility and quickness are considered impor-
tant for success in rugby league [22].
Abstract
The purpose of this study was to examine the influence of over-
reaching on muscle strength, power, endurance and selected bio-
chemical responses in rugby league players. Seven semi-profes-
sional rugby league players (V
˙
O
2max
= 56.1 ± 1.7 mL· kg
–1
·min
–1
;
age = 25.7 ± 2.6 yr; BMI = 27.6 ± 2.0) completed 6 weeks of pro-
gressive overload training with limited recovery periods. A short
7-day stepwise reduction taper immediately followed the over-
load period. Measures of muscular strength, power and endur-
ance and selected biochemical parameters were taken before
and after overload training and taper. Multistage fitness test run-
ning performance was significantly reduced (12.3%) following
the overload period. Although most other performance measures
tended to decrease following the overload period, only peak
hamstring torque at 1.05 rad· s
–1
was significantly reduced
(p < 0.05). Following the taper, a significant increase in peak
hamstring torque and isokinetic work at both slow (1.05 rad ·s
–1
)
and fast (5.25 rad ·s
–1
) movement velocities were observed. Min-
imum clinically important performance decreases were mea-
sured in a multistage fitness test, vertical jump, 3-RM squat and
3-RM bench press and chin-up
max
following the overload period.
Following the taper, minimum clinically important increases in
the multistage fitness test, vertical jump, 3-RM squat and 3-RM
bench press and chin-up
max
and 10-m sprint performance were
observed. Compared to resting measures, the plasma testoster-
one to cortisol ratio, plasma glutamate, plasma glutamine to glu-
tamate ratio and plasma creatine kinase activity demonstrated
significant changes at the end of the overload training period
(p < 0.05). These results suggest that muscular strength, power
and endurance were reduced following the overload training, in-
dicating a state of overreaching. The most likely explanation for
the decreased performance is increased muscle damage via a de-
crease in the anabolic-catabolic balance.
Key words
Athlete monitoring fatigue · recovery · hormones · team sport ·
overtraining
Training & Testing
116
Affiliation
1
School of Leisure, Sport and Tourism, University of Technology, Sydney, Australia
2
School of Health and Human Performance, Central Queensland University, North Rockhampton, Australia
3
School of Medical Sciences, RMIT University, Bundoora, Australia
Correspondence
Aaron Coutts Ph.D. · School of Leisure, Sport and Tourism · University of Technology ·
Kuring-gai Campus · P.O. Box 222 · Lindfield, NSW 2070 · Sydney · Australia · Phone: + 612 9514 5188 ·
Fax: + 612 9514 5195 · E-mail: aaron.coutts@uts.edu.au
Accepted after revision: March 27, 2006
Bibliography
Int J Sports Med 2007; 28: 116 – 124 © Georg Thieme Verlag KG · Stuttgart · New York ·
DOI 10.1055/s-2006-924145 · Published online July 11, 2006 ·
ISSN 0172-4622
A. Coutts
1
P. Reaburn
2
T. J. Piva
3
A. Murphy
1
Changes in Selected Biochemical, Muscular Strength,
Power, and Endurance Measures during Deliberate
Overreaching and Tapering in Rugby League Players
Downloaded by: Central Queensland University. Copyrighted material.
The physical conditioning programs prescribed for rugby league
players usually consist of a high volume of resistance training
that focuses on strength and power development, aerobic fitness
training, speed and agility sessions, as well as skill and tactical
development sessions. Like most high-level team sport athletes,
rugby league players often complete a large volume of high-in-
tensity training during the preseason preparation period so that
these physical capacities can be optimized prior to the competi-
tion season. These high training loads may increase the risk of
rugby league players developing overreaching (OR) or over train-
ing (OT).
High training loads with insufficient periodization of recovery
periods has been suggested to cause OR and OT in team sport
players, such as soccer [18, 25], European handball [8] and bas-
ketball [14]. To date, there have only been a few studies that have
examined the influence of OR on muscular strength, power and
endurance in team sport athletes [8,18]. These studies have
shown that when inappropriate physical training is completed
with inadequate recovery or regeneration, both reduced strength
performance and physiological function ensues. For example,
Kraemer et al. [18] demonstrated that soccer players entering a
competition with symptoms of OR such as low plasma testoster-
one concentration and elevated plasma cortisol, experienced
performance reductions in 20-yard sprint velocity, vertical jump
height and peak torque production during a maximal isokinetic
leg extension in the course of an 11-week soccer season. This
study highlighted that biochemical measures could be used to
identify fatigue in team sport athletes during the season. How-
ever, at present, there is still relatively little information about
the usefulness of these markers monitoring for fatigue in team
sport athletes.
Relatively few studies have systematically examined the use of
biochemical measures for monitoring fatigue and recovery in
team sport athletes [3 –5,15, 25]. In these studies, various hor-
monal [3 –5, 25], hematological [34], and immunological [5]
parameters have been used to identify early signs of OR/OT.
However, in accordance with similar studies that have been con-
ducted on endurance trained athletes [10], these studies have not
been able to provide clear and consistent biochemical markers of
impending OR/OT for team sport athletes.
The aim of this research was to examine the influence of over-
reaching on muscle strength, power and endurance characteris-
tics in rugby league players. This is the only investigation, to
date, to deliberately induce a state of OR in rugby league players
or team sport players in general. Additionally, this study is also
the first to examine changes in various performance and bio-
chemical markers of OR/OT in a team sport using a prospective
overload-training study. In accordance with similar research
with endurance athletes [9], it was hypothesized that increased
physical training will result in decreased performance and phys-
iological function, but will not significantly alter biochemical
markers previously used to identify OR/OT.
Methods
Subjects
Seven rugby league players (V
˙
O
2max
= 56.1 ± 1.7 ml· kg
–1
·min
–1
or
170.4 ± 8.2 mL ·kg bm
0.75
· min
–1
; age = 25.7 ± 2.6 yrs; BMI = 27.6 ±
2.0) from the same club volunteered to participate in the study.
The club competed in a state level rugby league competition
(Queensland Cup, Australia), which is the highest level of compe-
tition in the state for regional teams and players. Prior to partic-
ipation in this study, all players received written and verbal ex-
planation of the study informing them of all risks and benefits
associated with participation. Written informed consent was
then obtained. University Human Ethics Review Panel approval
was given for all experimental procedures.
Physical training
All subjects completed six weeks of physical training that in-
cluded 5 –7 sessions · week
–1
of field-based specific rugby league
training, aerobic endurance development, resistance, skill and
speed/agility training. The physical training in this study was
completed during the specific preparation period of the training
season and commenced 8 weeks prior to the first official compe-
tition match of the season. The physical training program was
designed to progressively overload the players during the initial
six weeks so that a state of OR was induced. The mean training
duration was progressively increased from ∼ 6 to 13 h ·week
–1
during the 6-week overload training period, through the addi-
tion of both resistance training, match play and rugby league
specific training (Table 4). The training load and monotony for
each subject was calculated according to the methods of Foster
et al. [6]. This method has previously been shown to be useful
for measuring a team sport athlete’s perception of physical train-
ing loads [17].
Following the 6 weeks of physical training, all subjects com-
pleted the same taper. A step-reduction taper consisting of three
field sessions and two resistance training sessions was com-
pleted over a 7-day period (Fig. 1). During the taper, there was a
reduction in both training time (55 %) and training intensity
(17.4%).
Resistance training
All players completed the same 7-week periodized resistance-
training program during the study. Resistance training sessions
were completed 2 –3 days· week
–1
. The resistance training exer-
cises prescribed during the overload period and taper are shown
in Tables 1 and 2, respectively. The resistance exercises com-
pleted on day 1 and 2 in Tables 1 and 2 were alternated through-
out the training period. The weight on the bar for core exercises
was calculated according to the methods suggested by Baker [1].
The players were encouraged to adjust these weights if they were
too heavy or too light. When training loads were altered, players
were instructed to inform the chief investigator. A detailed de-
scription of the resistance training periodization is shown in Ta-
ble 3. All resistance-training sessions were completed with at
least 24-h recovery from the previous resistance training session.
Testing procedures
Various physiological and performance measures were taken in
the 24 h prior to commencing the 6-week training protocol, fol-
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
117
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lowing the 6-week overload training and at the completion of the
7-day taper. Additionally, to determine the time-course of
changes in endurance shuttle running performance, the multi-
stage fitness test (MSFT) was conducted 24 h prior to training,
following the overload training period, and 5 days of the taper.
All measures were taken under standardized conditions and at
the same time of day.
Performance tests
All subjects were tested for various anthropometric, muscular
endurance, strength and power measures before and after the
training and taper periods. All tests, except the MSFT, were con-
ducted following 24 h of rest. The MSFT was measured during the
final day of training during the taper (day 5). Anthropometry
measures of the sum of nine skinfolds, body mass, stature and
girths were taken by a trained anthropometrist using standard
laboratory methods [27].
Multistage fitness test
Endurance performance was measured using the MSFT, using
previously reported methods [28]. For this test, the subjects were
required to run back and forth along a 20-m grassed track, keep-
ing in time with a series of audio signals from a compact disk
(Australian Coaching Council, Canberra, ACT). The running speed
was progressively increased until the players reached volitional
exhaustion. MSFT performance was taken as final distance trav-
elled when the player reached volitional fatigue. The intraclass
correlation coefficient (ICC) for test-retest reliability and typical
error of measurement (TEM) for the MSFT were 0.93 and 3.5%,
respectively.
Isoinertial strength testing
Muscle strength testing included a standardized warm-up fol-
lowed by a 3-RM parallel squat, 3-RM bench press and chin-up
maximum (chin-up
max
). The 3-RM parallel squat and bench press
testing procedures included two to three warm-up sets of five to
Table 1 Resistance training exercises completed during the 6-week
training overload period
Day 1 Day 2
Prone hamstring flicks* internal/external shoulder
Box jumps (40 cm)* bench throw*
Hang clean* push press*
Back squat underhand weighted chin-ups
Deadlift DB incline bench press
Barbell step-ups (40 cm) front military press
Hami-glut-raise abdominal circuit
* Power exercises
Fig.1 Mean (± SD) daily training load
(AU = Arbitrary unit).
Table 2 Resistance training exercises completed during the 7-day
taper period
Day 1 Day 2
Prone hamstring flicks internal/external shoulder
Full squat hang clean*
Bench throw* power shrug*
Clean pull* split jerk*
Push press* narrow grip bench press
Hami-glut-raise close grip pulldown
Abdominal circuit
* Power exercises
Table 3 Description of prescribed resistance training completed
during the 7-week training period
Week 1 2 3 4 5 6 Taper
Repetitions
per set
8765655
Sets per session 23 24 25 27 27 30 18– 21
Goal intensity
(%1-RM)*
78.5 81 83.5 86 83.5 86 55
Rest period
(min)
2222222.5
Sessions· week
–1
2233332
* General goal intensities are given only as a guide. Power exercises were com-
pleted at lighter %1-RM than strength exercises and the actual weight was individ-
ualized by the coach
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
118
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eight repetitions with light to moderate resistance. A successful
parallel squat required the thigh to descend to a parallel position,
where the trochanter head of the femur was in the same horizon-
tal plane as the superior border of the patella. A successful bench
press required the bar to be slowly lowered to the chest of the
subject and returned to full extension of both elbow joints. The
subjects were required to keep their hips and feet on the bench
and floor, respectively, at all times during each lift attempt. The
reliability of parallel squat (ICC: r = 0.96 and TEM% 2.32) and
bench press (ICC: r = 0.98 and TEM% 1.5) measures for this group
was high.
The chin-up
max
test was completed at least 10 min after the
bench press test. During this test, the subjects were instructed
to attempt as many full, unassisted, chin-ups as possible until vo-
litional fatigue. Each chin-up was completed on a horizontal bar
raised 2.5 m above the floor. A successful chin-up required the
subject to start with their chin above the horizontal bar and to
lower their body until full extension in both elbows and then lift
their body weight until the subjects chin returned to the starting
position. If assistance was offered by a spotter during any lifting
attempt, then the subject was instructed to stop. Subjects were
allowed three chin-up
max
trials with the highest number of repe-
titions being recorded. The reliability of the chin-up
max
test (ICC:
r = 0.99 and TEM% 2.6) for this group was high.
Speed
Running speed was assessed by 10-m and 40-m sprint times us-
ing electronic timing gates (Swift, Lismore, Australia) with the
photo-electric cells set at approximately chest height. Timing
gates were positioned in a straight direction at 10 m and 40 m
from a marked starting point. On an audible command, the play-
ers sprinted as quickly as possible along the 40-m course. Timing
commenced when the photoelectric cells positioned at the start
were initiated. Time to cover the 10-m and 40-m distance was
measured to the nearest 0.01 s, with the faster of two trials being
recorded. The reliability of 10-m (ICC: r = 0.91 and TEM % 2.0) and
40-m (ICC: r = 0.91 and TEM% 1.9) sprint tests was high.
Isokinetic strength
Isokinetic strength of the knee extensors and knee flexors (dom-
inant leg) was measured using an isokinetic dynamometer (Bio-
dex 3.0, Biodex Corporation, Shirley, NY, USA), which recorded
instantaneous muscular torques at preset constant angular ve-
locities of 1.05 rad· s
–1
and 5.25 rad ·s
–1
. Prior to beginning the
isokinetic strength assessment, subjects completed a standard-
ized 5-min warm-up of cycling on a cycle ergometer (Monark
818E, Monark, Stockholm, Sweden) at a cadence of 50 rpm with
a load of 0.5 kp. The subject was then seated on the dynamome-
ter in an adjustable chair, and stabilized by straps so that the axis
of rotation of the knee joint was aligned with the axis of rotation
of the dynamometer shaft. A resistance pad was positioned on
the thigh proximal to the knee joint so that the knee extensors
and flexors could be isolated. Straps were used to stabilize the
upper body, hips and nondominant leg. The cuff of the dyna-
mometers’ lever arm was attached proximal to the medial mal-
leoli. All positions were recorded and standardized to assure reli-
ability of testing conditions.
Prior to each test set, a series of submaximal trials at each testing
velocity were conducted to prepare them for each test. Concen-
tric strength of the knee extensors and flexors was determined
during one set of three maximal concentric contractions of the
quadriceps and hamstring muscles through a 90
8
range of mo-
tion at 1.05 rad ·s
–1
and 5.25 rad· s
–1
. The highest gravity-cor-
rected torque produced (Nm) during each set was taken as the
maximal isokinetic strength for that velocity. Total work (J) com-
pleted for each set at both lifting velocities was also calculated
during each testing session.
Vertical jump
Vertical jump (VJ) height was assessed using a Vertec
®
jumping
device consisting of a series of moveable marker vanes spaced
at 1-cm intervals (Sports Imports, Columbus, OH, USA). Each
subject stood side-on to the Vertec
®
with their heels placed on
the ground. Prior to each test jump, the subjects were asked to
reach upward as high as possible fully elevating the shoulder to
displace the zero reference vane. The take-off was from two feet
with no preliminary steps or shuffling. An arm swing and coun-
ter movement was used with the subject jumping as high as pos-
sible to displace the vane. The height of the jump (cm) was calcu-
lated as the difference between the highest vane reached and the
zero reference vanes. Each subject performed three trials, with
the best of these trials being recorded. The reliability of VJ mea-
sures for this test was high (ICC: r = 0.97 and TEM% 2.1).
Biochemistry
Testosterone, cortisol, adrenocorticotrophic hormone (ACTH),
creatine kinase (CK), erythrocytes, hemoglobin, hematocrit, plas-
ma glutamine and glutamate measures were taken prior to, and
following the 6-week overload period and also following the 7-
day taper. All hematological measures were taken in a fasted
state between 5:30 and 7:30 a.m. in the mornings of testing to
avoid circadian variations.
Table 4 Mean training load, monotony and frequency measured during the study period (mean ± SD)
Measure Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Taper 6-week train-
ing period
Training load (AU) 1387 ± 105 1811 ± 159
#
2285 ± 121
#
2403 ± 167
#
2712 ± 219
#
3296 ± 298
#
1420 ± 25
#
2316 ± 86
Monotony 1.35 ± 0.07 1.17 ± 0.10
#
1.85 ± 0.13
#
1.51 ± 0.23
#
2.00 ± 0.16
#
1.84 ± 0.10 1.29 ± 0.01
#
1.57 ± 0.32
Sessions
completed
556667535
#
Significantly different to previous measure (p < 0.05); AU = arbitrary unit
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
119
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Blood samples were taken by a trained phlebotomist in a quiet
laboratory room maintained at constant temperature (20–
23
8
C). All subjects were asked to refrain from drinking coffee,
tea, chocolate or cola drinks that morning or the previous even-
ing, as well as avoiding alcohol during the previous 24-h period.
All blood samples were taken with the subject in a resting, seated
position, following 20 min of seated rest. Three 10-mL samples
(1 × lithium heparin tubes [10 mL]; 1 × pre-chilled ethylenedia-
minetera-acteic acid (EDTA) [10 mL]; 1 × serum separator tube
(SST) tube [10 mL]) of blood were collected from the antecubital
vein on each occasion, using a winged cannula attached to a va-
cutainer (Becton Dickinson, Rutherford, NJ, USA) bleeding sys-
tem. All samples were then stored within an ice-bath immedi-
ately following collection. The lithium heparin tubes were cen-
trifuged for 5 min at 4000 g. The samples were then transported
in a refrigerated transport pack for immediate analysis. Once the
samples arrived at the diagnostic laboratory (approximately
10 min), they were prepared for analysis.
Plasma total testosterone was determined via a solid-phase
125
I
radioimmunoassay using a gamma radiation counter (LKB Wal-
lac, St Albans, UK). Plasma cortisol was determined via immuno-
assay, through a fluorescence polarization immunoassay (FPIA)
using a TDx/TDxFLx analyser (Axysm, Abbott, Irving, TX, USA).
Hematocrit, hemoglobin and erythrocyte number were deter-
mined with a Coulter
®
MaxM A/L Flow Cytometer (Coulter Elec-
tronics Limited, Luton, UK). Plasma glutamine and glutamate
were also determined enzymatically using the method of Lund
[21]. All blood analyses, except for ACTH, were conducted at Dr.
T. B. Lynch Research and Diagnostic Laboratories, Rockhampton,
Australia. All diagnostic laboratories used in this study held cur-
rent quality assurance certification (ISO 9001).
Statistical analyses
The means and standard deviations (SD) were calculated for each
dependent variable. The data were analyzed using an analysis of
variance (ANOVA) for repeated measures to determine if there
were differences between each testing occasion. When a signifi-
cant F-value was achieved, Scheffé post hoc test procedures were
used to locate the difference between the means. The minimum
clinically important difference (MCID), or smallest worthwhile
change perceived to be practically significant for the average ath-
lete, was calculated for most performance variables. MCID was
determined to be greater than the typical error of measurement
in the performance tests [16]. The MCID for MSFT, vertical jump,
3-RM bench press, 3-RM squat, chin-up
max
, 10-m sprint and 40-
m sprint were 1.4 mL ·kg
–1
·min
–1
, 1.3 cm, 1.7 kg, 3.3 kg, 0.4 reps,
0.04 s and 0.10 s, respectively. Pearson correlation coefficients
were calculated to determine relationships between selected
variables. The SPSS statistical software package, version 11.5
(SPSS Inc., Chicago, IL, USA), was used for statistical calculations.
The level of significance was set at p ≤ 0.05.
Results
Physical training
In the present study, all subjects completed 6 weeks of progres-
sive overload training (Table 4). Training duration was progres-
sively increased for each week followed by a significant reduc-
tion in training load during the 7-day taper (p < 0.001) (Table 5).
The training time during the taper period was ∼ 55% less than the
previous training week. The training intensity was significantly
lower in the taper than the final week of the overload period
(RPE: 4.6 ± 0.2 vs. 3.8 ± 0.1; p < 0.01). The time spent during both
field and resistance training during the week prior to the taper
and during the 7-day taper can be seen in Table 5. During the 6-
week overload period, significantly more time (90 %, p < 0.001)
was spent in field training compared to resistance training.
Physiology and performance
Table 6 shows the physiological variables that changed signifi-
cantly during the 6-week overload training period. There were
significant main effects observed in MSFT performance over time
(p < 0.01) during the 6-week training period and five-day taper. A
significant correlation was observed between the change in
MSFT performance and the change in training load (r = – 0.84;
p < 0.001).
Peak torque developed by both the knee extensors and flexors
and the total amount of work completed at a movement velocity
of 1.05 rad· s
–1
was significantly decreased following the over-
load period (p < 0.05) and significantly increased following the
taper (p < 0.05). MCID (reductions) were observed for MSFT, VJ,
3-RM bench press, 3-RM squat and chin-up
max
performance
following the overload training period. In contrast, MCID (in-
creases) were observed in MSFT, VJ, 10-m sprint, isoinertial 3-
RM bench press, isoinertial 3-RM squat and chin-up
max
perform-
ance following the taper period. The only MCID for improve-
ments in performance from before training to following taper
was in chin-up
max
.
Biochemistry
Table 7 shows hormonal changes during the 6-week overload
training period. The testosterone to cortisol (T/C) ratio was sig-
nificantly decreased with overload training (p < 0.05). No signifi-
cant changes were observed in plasma cortisol measures. Addi-
Table 5 Training time (min) for the field and resistance training during the study period (mean ± SD)
Training Mode Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Taper 6-week training period
Field training (min) 239 ± 5 267 ± 6
#
326 ± 7
#
339 ± 27 350 ± 6 562 ± 16
#
185 ± 3
#
332 ± 78
Resistance training (min) 104 ± 3 135 ± 24
#
205 ± 14 221 ± 25 262 ± 15 170 ± 24 147 ± 8
#
197 ± 63
Combined training (min) 343 ± 5 402 ± 23
#
531 ± 12
#
560 ± 27
#
612 ± 18
#
732 ± 38
#
332 ± 9
#
531 ± 134
#
Significantly different to previous measure (p < 0.05)
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
120
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tionally, there were no significant changes in any hormonal val-
ues during the taper (p > 0.05).
Table 8 shows the changes in the hematological variables during
the course of the training and taper periods. CK activity signifi-
cantly increased during the 6-week training period. No signifi-
cant changes were observed over time in erythrocyte number,
hematocrit or hemoglobin. Significant changes in CK activity
(p < 0.01) were measured during the taper.
There were no significant changes in plasma glutamine concen-
tration over the 6-week overload training period. However, plas-
ma glutamate was significantly elevated at the end of the train-
ing period (p < 0.05). Accordingly, the glutamine to glutamate ra-
tio (Gln/Glu) was also significantly lower at the end of the train-
ing period (p < 0.05) (Table 8). During the taper, plasma gluta-
mate (p < 0.05) and Gln/Glu (p < 0.05) were significantly de-
creased.
Discussion
The purpose of this research was to examine the influence of OR
on muscle strength, power and endurance characteristics in rug-
by league players. The present findings show that with deliberate
OR, semi-professional rugby league players have a decreased ca-
pacity to produce force at slower movement velocities. Addition-
ally, the present results also demonstrate that inappropriate
high-intensity training for rugby league may also cause a tempo-
rary reduction in MSFT and thus aerobic endurance performance.
In this study, 7 semi-professional rugby league players were de-
liberately overreached by increasing resistance training, endur-
ance and rugby league specific skill training workloads over a 6-
week period. Training load was progressively increased during
the 6-week overload period by increasing training frequency
and duration, which lead to a reduction in MSFT performance.
The 12.3% reduction in MSFT performance during the overload
period is well above the typical error of measurement for this
test (3.5 %) showing that there was both a practically [16] and
statistically significant reduction in maximal aerobic running
performance. Previous research has shown V
˙
O
2max
to decrease
following increased training loads in endurance-trained athletes
[9, 20, 33], but not in team sport players [4, 35]. The decreased
MSFT performance following the 6-week overload training in
the present study may be due to a number of physiological and
biochemical factors such as reduced muscle glycogen levels, in-
creased muscle damage, or simply due to acute fatigue diminish-
ing maximal effort. The significant reduction in the T/C ratio and
elevated CK activity following the 6-week overload training peri-
Table 7 Hormonal variables of OR rugby league players during 6
weeks of overload training and 7-day taper (mean ± SD)
Measure Pre-
training
Post-
training
Taper
Testosterone (ng · dL
–1
) 573 ± 114 471 ± 129 545 ± 111
Cortisol (
μ
g·dL
–1
) 21.2 ± 6.6 22.8 ± 4.7 21.7 ± 4.0
T/C ratio 31.4 ± 6.6 22.11 ± 5.4* 23.9 ± 3.1*
Values are means ± SD; T/C = testosterone to cortisol ratio; * significantly different
to pretraining (p < 0.05)
Table 8 Mean (± SD) hematological measures during a 6-week over-
load training and 7-day taper period
Measure Pre-
training
Post-
training
Taper
Creatine kinase
(U · L
–1
)
414 ± 171 1329 ± 1003* 498 ± 402*
Erythrocytes
(·10
6
·mm
–3
)
5.07 ± 0.32 4.98 ± 0.34 5.01 ± 0.10
Hemoglobin (g · dL
–1
) 155.6 ± 6.5 152.3 ± 4.4 153.6 ± 6.0
Hematocrit (%) 46.1 ± 2.1 45.1 ± 1.7 45.6 ± 2.2
Glutamine
(
μ
mol · L
–1
)
0.542 ± 0.067 0.491 ± 0.060 0.525 ± 0.036
Glutamate
(
μ
mol · L
–1
)
0.117 ± 0.014 0.143 ± 0.029* 0.120 ± 0.015
Gln/Glu ratio 4.70 ± 0.78 3.54 ± 0.81* 4.41 ± 0.50
* Significantly different to pretraining (p < 0.05)
Table 6 Performance and physiological variables during 6 weeks of
overload training and 7-day taper (mean ± SD)
Measure Pretraining Post-training Taper
Body mass (kg) 86.1 ± 10.0 85.3 ± 9.4 85.3 ± 9.6
MSFT (m) 2291 ± 127 2054 ± 199*
M
2437 ± 67
#M
Vertical jump (cm) 61.7 ± 10.6 59.4 ± 9.6
M
62.4 ± 9.9
M
Running speed
10 m (s) 1.89 ± 0.09 1.92 ± 0.11 1.88 ± 0.10
M
40 m (s) 5.42 ± 0.18 5.46 ± 0.20 5.44 ± 0.19
Isoinertial strength
3-RM squat (kg) 141.2 ± 21.8 133.9 ± 18.2
M
143.6 ± 24.8
M
3-RM bench press
(kg)
115.0 ± 18.7 109.3 ± 17.9
M
115 ± 17.3
M
Chin-up
max
(reps) 15.6 ± 1.9 13.4 ± 2.1
M
16.0 ± 1.7
M
Isokinetic strength and power
1.05 rad·s
–1
Peak quadriceps
torque (Nm)
222.4 ± 50.6 164.5 ± 19.5* 239.5 ± 38.2
#
Peak hamstrings
torque (Nm)
151.8 ± 44.9 117.3 ± 20.4* 135.6 ± 16.2
#
Set work (J) 967 ± 244 724 ± 116* 1074 ± 152
#
*
5.25 rad · s
–1
Peak quadriceps
torque (Nm)
149.1 ± 20.9 162.8 ± 15.0 176.2 ± 28.7
Peak hamstrings
torque (Nm)
96.5 ± 11.8 108.4 ± 13.6 128.1 ± 22.3*
Set work (J) 603 ± 83 705 ± 91 770 ± 103*
#
Significantly different to previous measure (p < 0.05); * significantly different to
pretraining (p < 0.05);
M
minimally clinically important difference compared to pre-
vious measure
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
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od suggests that the players were in a catabolic state with elevat-
ed levels of muscle damage when the MSFT performance was re-
duced. Although there were not significant correlations between
the changes in physiological measures and performance, it is
likely that these factors did contribute to the reduction in aerobic
performance.
There were no statistically significant changes in VJ or isoinertial
strength tests in the present study. Nonetheless, MCID changes
were identified for these test measures. For example, the reduc-
tion in VJ, isoinertial 3-RM bench press, isoinertial 3-RM squat
and chin-up
max
tests during the overload training period were
- 3.7 %, – 5.0 %, – 5.3% and – 13.8%, respectively. Since the reduc-
tion in each test score was greater than the respective typical
error of measurement, it is suggested that the changes in each
of these tests are of practical importance.
Significant reductions in peak torque developed by the knee flex-
ors at 1.05 rad ·s
–1
were observed following the overload training
period. In contrast to our initial hypothesis, we found that knee
flexor and extensor strength measured at slower speeds
(1.05 rad ·s
–1
) was significantly reduced during OR. However,
there was a nonsignificant increase in isokinetic knee extensor
and flexor strength at faster movement velocities (5.25 rad · s
–1
).
The results suggest that the training undertaken during the 6-
week overload period in this study, which consisted of a 68 %
greater time spent in field training than resistance training, had
a greater negative influence on the type I motor units than the
type II motor units. This phenomenon was also previously ob-
served in 11 elite college level starting soccer players whose peak
isokinetic knee extensor strength was reduced at 1.05 rad ·s
–1
,
but not 5.25 rad ·s
–1
during an 11-week soccer season [18]. These
previous investigators suggested that the majority of training for
soccer players mainly involved type I motor units and, therefore,
they were the most effected by the insufficient recovery period.
Furthermore, other studies have suggested that the type I myosin
heavy chains (MHC) are more affected by run training than re-
sistance training [12]. Accordingly, the greater volume of lower
intensity “on legs” exercise (e.g., running and skill training; see
Table 5) in this study may explain why the isokinetic strength at
the lower speeds were more affected than the higher speeds dur-
ing the overload training period.
In the present study, hormone and other blood measures were
assessed in order to elucidate the mechanisms underlying the
changes in muscular strength and power with fatigue and recov-
ery. The hormone results show a nonsignificant tendency for a
reduction in testosterone concentration and an increase in corti-
sol concentration following the overload training period (Table
7). There was also a significant reduction in the T/C ratio follow-
ing the overload period. These results agree with other similar
research that show that monitoring T/C ratio measures maybe
useful for monitoring adaptation and recovery to training and
match play stress in team sport athletes [3]. A limitation in the
practical application of the results of this study to field is that
venipuncture is required which can be intimidating for some
players. To overcome this limitation, coaches and scientists may
like to consider measuring T/C ratio using noninvasive salivary
samples [3].
A reduction in the T/C ratio is generally considered as an indica-
tor of the bodies “anabolic-catabolic balance” and has previously
been considered a useful tool for diagnosing OR/OT. It is possible
that the change in T/C ratio was due to inadequate recovery be-
tween exercise sessions at the end of the overload period, which
also reduced the rate of muscle protein and glycogen resynthesis,
increased muscle damage and increased inflammation, which
ultimately lead to reduced ability to generate force. The reduced
ability to generate muscular force may also be related to muscu-
lar performance measures such as speed, VJ and isoinertial
strength.
It is also likely that short-term peripheral fatigue may partially
explain the diminished muscular strength, power and endurance
performance following the overload training period. A recent re-
view clearly demonstrated that muscle damage can result in im-
mediate and prolonged reduction in muscle force generating ca-
pacity in both isotonic and isokinetic tests [2]. The measures of
muscle damage in the present study, CK activity and plasma glu-
tamate, were both significantly elevated at the end of the over-
load period, which coincided with significant changes in isoki-
netic force at slow velocity and practical reductions in isoinertial
strength measures. These results are in agreement with many
previous studies showing that overreached athletes usually suf-
fer considerable levels of muscle trauma [7,19, 31].
Recent investigators have suggested that elevated plasma gluta-
mate levels can be used to identify impaired recovery from high-
intensity training or an inadequate recovery period [30]. The
present results are in agreement with previous studies that have
shown increased plasma glutamate and reduced exercise per-
formance following intensified training periods [11, 30]. Gluta-
mate along with glutamine has a role in acid-base balance and
de novo synthesis of nucleotides, and is also an important regu-
lator of protein synthesis and degradation [29]. Due to these
properties, it is most likely that glutamate plays an important
role in the repair/regenerative responses to daily muscle loading.
Accordingly, we hypothesize that the decreased muscle gluta-
mate observed in the present study may also be associated with
reduced strength performance following the overload training
period. Further research needs to be completed to determine
the role that glutamate plays in these processes.
Recent studies have also shown the Gln/Glu ratio to decrease fol-
lowing intensified training with levels lower than 3.58 suggest-
ed, indicating a state of OR [11, 30]. In agreement with these pre-
vious studies, the significant change in the Gln/Glu ratio ob-
served in the current study appeared to be due to increased plas-
ma glutamate levels rather than a reduction in glutamine con-
centration alone. Furthermore, we also measured a rebound ef-
fect following the taper where plasma glutamate decreased and
glutamine levels increased so that the Gln/Glu ratio returned to
levels previously suggested to represent that athletes were toler-
ating training [30]. The failure of the Gln/Glu ratio to return to
pretraining levels, in the present study, may suggest a longer
taper period may have been warranted. This is supported by re-
cent research that has suggested that tapers up to 28 days can
show improvements adaptations in physiology and performance
[23, 24].
Coutts A et al. Overreaching in Team Sports … Int J Sports Med 2007; 28: 116–124
Training & Testing
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This study, to our knowledge, is the first to report on endurance,
strength, power and biochemical changes during a preseason
taper in team sport athletes. Most performance tests tended to
improve following the seven-day taper, suggesting some adapta-
tion had taken place. Following the taper, only isokinetic mea-
sures of set work at 1.05 and 5.25 rad· s
–1
and peak hamstring
torque at 5.25 rad ·s
–1
were significantly improved from baseline
measures following the 7-day taper. Notably, however, most oth-
er performance variables (MSFT, VJ, 3-RM squat, 3-RM bench
press, chin-up
max
and 10-m sprint) demonstrated MCID changes
with tapering. Combined, these results show that a short, step-
wise taper can concurrently improve endurance, strength and
power measures in team sport athletes.
The MCID increases in MSFT, VJ and 10-m sprint performance,
combined with the significant increases in isokinetic strength,
show that muscular strength, power and endurance were im-
proved with the short taper. It is most likely that the improve-
ments in performance are related to changes in muscle fiber
properties. Previous studies have shown activity specific changes
in myocellular size, power and contractility are dependent upon
the type of training completed during the taper [12,26, 32].
Despite all biochemical variables reported in this study tending
to return to baseline values, only CK activity was significantly
changed during the taper, suggesting that training intensity was
reduced or an increased tolerance to training loads occurred.
These findings agree with the majority, but not all previous re-
search employed tapers of between 6 –28 days in duration with
endurance athletes [24]. To our knowledge, no studies have ex-
amined CK activity in response to tapering in team sport ath-
letes. However, previous investigators suggested that CK activity
has extremely high variability amongst individual athletes and
that significant reductions in CK activity are observable during a
reduction in training loads following days of intensive, prolonged
exercise [13]. The most likely cause for the reduction in CK activ-
ity during the taper in the present study is a reduction in the
damage to tissue cell membrane from both the repeated strenu-
ous exercise and direct muscle trauma. On this basis, we suggest
that CK can be used to monitor for acute recovery from heavy
training loads in team sport athletes.
In conclusion, this study showed that when relatively large loads
of aerobic endurance, resistance, speed and skill training with in-
adequate periods for recovery are completed, reductions in phys-
ical performance could occur. This type of inappropriate training
can cause a reduction in the T/C ratio, increased CK activity, in-
creased plasma glutamate concentrations and decreased Gln/
Glu ratio. The reduction in performance with OR appears to be
related to the type of training completed. For example, in this
study, a large volume of training that recruited mostly slower
motor units was completed (i.e., field vs. resistance training)
and consequently, performance at slower lifting speeds (which
recruit these slower motor units) were most negatively affected.
The present results also demonstrated that if a stepwise reduc-
tion taper is completed following a period of OR, super compen-
sation in muscular strength, power and endurance may occur.
This super compensation appears to be related to increased
anabolism and a decrease in muscle damage.
Acknowledgements
This research was kindly supported by Dr. T. B. Lynch Pathology
Research Laboratories, Rockhampton, Australia.
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