Relationship Between Pre-Game Free Testosterone Concentrations and Outcome in Rugby Union.

Abstract

Purpose:
To assess the measures of salivary free testosterone and cortisol concentrations across selected rugby union matches according to game outcome.

Methods:
Twenty-two professional male rugby union players were studied across 6 games (3 wins and 3 losses). Hormone samples were taken 40 min before the game and 15 min after. The hormonal data were grouped and compared against competition outcomes. These competition outcomes included wins and losses and a game-ranked performance score (1-6).

Results:
Across the entire team, pregame testosterone concentrations were significantly higher during winning games than losses (P = 5.8 × 10-5). Analysis by playing position further revealed that, for the backs, pregame testosterone concentrations (P = 3.6 × 10-5) and the testosterone-to-cortisol ratio T:C (P = .038) were significantly greater before a win than a loss. Game-ranked performance score correlated to the team's pregame testosterone concentrations (r = .81, P = .049). In backs, pregame testosterone (r = .91, P = .011) and T:C (r = .81, P = .05) also correlated to game-ranked performance. Analysis of the forwards' hormone concentrations did not distinguish between game outcomes, nor did it correlate with game-ranked performance. Game venue (home vs away) only affected postgame concentrations of testosterone (P = .018) and cortisol (P = 2.58 × 10-4).

Conclusions:
Monitoring game-day concentrations of salivary free testosterone may help identify competitive readiness in rugby union matches. The link between pregame T:C and rugby players in the back position suggests that monitoring weekly training loads and enhancing recovery modalities between games may also assist with favorable performance and outcome in rugby union matches.

Full text

324
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ORIGINAL INVESTIGATION
International Journal of Sports Physiology and Performance, 2014, 9, 324 -331
http://dx.doi.org/10.1123/IJSPP.2013-0106
© 2014 Human Kinetics, Inc.
Relationship Between Pregame Concentrations
of Free Testosterone and Outcome in Rugby Union
Christopher M. Gaviglio, Blair T. Crewther, Liam P. Kilduff,
Keith A. Stokes, and Christian J. Cook
Purpose: To assess the measures of salivary free testosterone and cortisol concentrations across selected rugby
union matches according to game outcome. Methods: Twenty-two professional male rugby union players were
studied across 6 games (3 wins and 3 losses). Hormone samples were taken 40 min before the game and 15
min after. The hormonal data were grouped and compared against competition outcomes. These competition
outcomes included wins and losses and a game-ranked performance score (1–6). Results: Across the entire
team, pregame testosterone concentrations were signicantly higher during winning games than losses (P = 5.8
× 10
–5
). Analysis by playing position further revealed that, for the backs, pregame testosterone concentrations
(P = 3.6 × 10
–5
) and the testosterone-to-cortisol ratio T:C (P = .038) were signicantly greater before a win
than a loss. Game-ranked performance score correlated to the team’s pregame testosterone concentrations (r
= .81, P = .049). In backs, pregame testosterone (r = .91, P = .011) and T:C (r = .81, P = .05) also correlated
to game-ranked performance. Analysis of the forwards’ hormone concentrations did not distinguish between
game outcomes, nor did it correlate with game-ranked performance. Game venue (home vs away) only affected
postgame concentrations of testosterone (P = .018) and cortisol (P = 2.58 × 10
–4
). Conclusions: Monitoring
game-day concentrations of salivary free testosterone may help identify competitive readiness in rugby union
matches. The link between pregame T:C and rugby players in the back position suggests that monitoring weekly
training loads and enhancing recovery modalities between games may also assist with favorable performance
and outcome in rugby union matches.
Keywords: salivary hormones, competition, monitoring, endocrine
Rugby union is a sport characterized by a high degree
of aggressive impacts and interactions (eg, grappling for
possession of the ball), with forwards generally involved
in more body-contact situations than the backs.
1
In
general the forwards are required to gain and retain pos-
session of the ball. Conversely, the backs spend greater
time in free running while controlling the possession of
the ball obtained by the forwards.
2
Testosterone and cortisol have been studied in rela-
tion to training and performance outcomes in sport.
3–5
For example, testosterone concentrations are related
to the neuromuscular expression of speed, power, and/
or strength.
6,7
Mood states such as competitiveness,
drive, persistence, and contribution to winning are also
associated with higher testosterone levels,
8
along with
aggressive and dominant behaviors.
9
Given these associa-
tions, the measurement of testosterone before training or
competition could help predict a favorable performance
outcome in sports that rely on these physiological and
behavioral actions.
The reporting of preevent testosterone concentra-
tions as a predictor of successful outcomes in sport is
equivocal. A study of elite fencers suggested that higher
blood testosterone concentrations increased their chance
for success,
10
and a similar trend was noted in judoists,
11
although there was no clear distinction between hormone
concentration and outcome. In separate studies on judo-
ists
12
and tennis players,
13
pregame testosterone concen-
trations also showed no relevance to either wins or losses.
Links between the competition responses of both
free and serum (total) testosterone and sporting out-
comes are also equivocal.
13–16
In wrestlers, the pregame
to postgame competition changes in serum testosterone
and cortisol concentrations were indicators for success
in competition,
14
and a similar trend for only serum
testosterone was seen in winners in the same sport.
17
In
tennis, the difference between winners and losers was
also seen in the rise in mean testosterone from pregame
to immediately postmatch.
13
However, in basketball
16
no
signicant difference between the free testosterone and
Gaviglio is with the School of Human Movement Studies, Uni-
versity of Queensland, St Lucia, QLD, Australia. Crewther and
Cook are with the Hamlyn Centre, Imperial College, London,
UK. Kilduff is with the College of Engineering, Swansea
University, Swansea, UK. Stokes is with the Dept for Health,
University of Bath, Bath, UK.

Testosterone and Competition Outcome 325
cortisol responses and game outcomes were observed, but
the testosterone response did show a signicant relation-
ship between the score:time-playing ratio, an indicator
of individual participation and perception in the outcome
of that game.
The testosterone-to-cortisol ratio (T:C) has been
examined as a putative marker of the anabolic to catabolic
hormonal balance in the body. This ratio was originally
hypothesized as an indicator of overtraining and recovery
from intensive physical activity,
18
although more recent
investigations have queried its validity.
19,20
Few studies
have investigated the relationship between T:C and per-
formance outcomes in sport. As a predictive marker in
golfers,
21
a low T:C was related to lower scores (ie, better
performance). In elite rugby union players, a postmatch
decline in T:C was reported after 2 matches in conjunction
with a pregame increase across a 3-game period, although
game outcomes were not reported.
22
Previous research has often included only 1 or 2
competitive events (and often weeks apart). Thus, the
purpose of this study was to improve on this by exam-
ining game-day measures of salivary free testosterone
and cortisol concentrations and the related outcomes of
professional rugby union across 6 consecutive games. We
hypothesized that salivary free-testosterone concentra-
tions and T:C would be higher before a win (vs a loss)
and that both measures would correlate to a game-ranked
performance score.
Methods
Subjects
Twenty-two male rugby union players from a professional
rugby union team were recruited for this study. The age,
height, and body-mass details for participants are pre-
sented as a team and for the 2 major positional groupings
(forwards and backs) in Table 1. Subjects were informed
of the study protocols and signed informed consent before
testing began, and ethics approval was obtained from a
university ethics committee.
Design
This study was conducted midseason over the course of
6 weeks. Players continued to train midweek according
to their usual training schedules, and the games were
played during the weekend on a home-and-away basis.
On each of the days immediately before testing, players
were encouraged to sleep well (>7 h), consume a good
breakfast (each player standardized across testing ses-
sions), and maintain their uid intake (at least 750 mL)
during the 2 hours before each testing session. During the
course of this study, the subjects were not on medications
other than several for asthma control.
Hormone Assessment
Saliva samples were taken at times chosen to minimize
any interruption of the players’ game preparation and to
keep diurnal consistency in sampling. Saliva was used due
to its ease of compliance, low invasiveness, and ability to
track the biologically active “free” hormone.
23
Pregame samples were taken 40 minutes before the
start of the game. Postgame samples were taken 15 min-
utes either after the player was substituted off the eld
or after the game’s completion. For each test, a 2-mL
saliva sample was collected and stored at –20°C before
analysis. Saliva was assayed for testosterone and cortisol
concentrations by a private commercial laboratory (HFL
Sport Science Laboratories, UK) using commercially
available kits (Salimetrics Enzyme Immunoassay Kits,
Salimetrics, USA) according to the manufacturer’s
instructions. Interassay coefcients of variation (based
on low and high control samples) for testosterone and
cortisol were both <10%.
Game Day-Performance
Game-day performance was determined by the overall
outcome, being a win, loss, or draw, based on the nal
score. A game-ranked performance score (1–6, 6 being
the best score possible) was also assigned to each game
(Table 2).
The win percentage was calculated from historical
data (obtained via http://www.premiershiprugby.com)
gathered from all of the games played against that relevant
opposition (Table 3).
Statistical Analyses
Pregame and postgame hormone concentrations and
hormonal changes across each game (perigame) were
tabulated for each player, game, and result. The perigame
hormone value was calculated by dividing the postgame
Table 1 Physical Characteristics of the Rugby Union Forwards
and Backs, Mean (SD)
Team (N = 22) Backs (n = 11) Forwards (n = 11)
Age (y) 27.8 (4.0) 27.1 (3.5) 28.4 (4.4)
Height (cm) 186.9 (7.7) 184.1 (6.6)* 189.1 (8.0)
Body mass (kg) 103.4 (11.6) 93.8 (8.0)*** 111.0 (7.8)
Signicantly different from forwards: *P < .1, ***P < .01.

326 Gaviglio et al
hormone value by the pregame hormone value (post-
game ÷ pregame = perigame). The hormone results for
winning and losing were compared using paired t tests.
Comparisons were conducted on the team data (team) and
for the 2 different positional groups in the team (backs
and forwards). To determine if game venue (home or
away) affected our results, the hormone data were pooled
according to game venue and compared using paired t
tests. The bivariate relationships between the hormonal
variables and the game-ranked outcomes were assessed
using Pearson product–moment correlations. The level
of signicance was set at P ≤ .05.
Results
The pregame, postgame, and perigame measures of
testosterone, cortisol, and T:C are presented in Table 4.
Table 2 Results and Classifications for Each of the Rugby Games Played
Score Outcome Classification Clarification notes on appointing classification
1 Loss Bad Due to amount of points lost by and poor skill decision making and execution during the
game.
2 Loss Unlucky A game that could have been won. A result of a close score or a game that was lost in
the last few minutes.
3 Draw Draw
4 Win Average A game resulting in a close score or that was won in the last few minutes. A perceived
lack of dominance during the game.
5 Win Good A win where the team played well against the opposition. A good performance not nec-
essarily reected by the score line.
6 Win Good + A dominant win. Reected usually by the quality of the opponent (good) and the score
line.
Note: Score = game-ranked performance score; outcome = game result.
Table 3 Game-Day Information for Elite Rugby Union Players
Game Outcome Rating Score Game venue Historical win %
1 Loss Bad 1 Home 70%
2 Loss Unlucky 2 Away 37%
3 Win Average 4 Home 50%
4 Loss Bad 1 Away 50%
5 Win Good+ 6 Home 48%
6 Win Good 5 Away 63%
Note: Outcome = game result; rating = subjective performance rating; score = game-ranked per-
formance score.
Table 4 Salivary Hormone Concentrations of Elite Rugby Union Players on Game Day, Mean (SD)
Measure
Game 1
(loss) Game 2 (loss) Game 3 (win) Game 4 (loss) Game 5 (win) Game 6 (win)
Pregame testosterone (pg/mL) 78 (22) 99 (31) 121 (44) 94 (33) 111 (41) 114 (32)
Pregame cortisol (μg/dL)
0.3 (0.2) 0.3 (0.1) 0.4 (0.7) 0.2 (0.1) 0.2 (0.1) 0.3 (0.1)
Pregame T:C ratio 435 (177) 533 (334) 553 (338) 506 (324) 721 (377) 494 (232)
Postgame testosterone (pg/mL) 133 (52) 154 (58) 143 (86) 159 (81) 143 (68) 198 (94)
Postgame cortisol (μg/dL)
0.9 (0.5) 0.7 (0.4) 0.6 (0.5) 0.6 (0.2) 0.6 (0.3) 1.0 (0.5)
Postgame T:C ratio 264 (105) 270 (148) 363 (256) 237 (137) 237 (64) 233 (108)
Perigame testosterone 1.8 (0.7) 1.7 (0.8) 1.4 (1.2) 1.7 (0.9) 1.5 (0.9) 1.8 (0.9)
Perigame cortisol 3.1 (1.7) 3.9 (2.8) 2.9 (3.2) 5.3 (7.5) 5.3 (5.6) 4.0 (3.1)
Perigame T:C ratio 0.6 (0.6) 0.6 (0.3) 0.9 (0.9) 0.7 (0.3) 0.4 (0.2) 0.5 (0.2)
Abbreviations: T:C = testosterone-to-cortisol. Note: Perigame = postgame ÷ pregame hormone concentration.

Testosterone and Competition Outcome 327
Table 3 outlines the corresponding game information
and results. Table 3 also shows the subjective game rat-
ings, game-ranked score, and other relevant information
such as game venue and historical win percentage against
the corresponding opposition. Historical win percentage
had no obvious effect on pregame hormone levels. Game
venues (home vs away) only had an effect on postgame
testosterone (P = .018) and postgame cortisol (P = 2.58
× 10
–4
) concentrations, both being higher in away games
(Table 5).
As a team, pregame testosterone concentrations were
signicantly higher before a win (P = 5.8 × 10
–5
) than a
loss (Table 6). For the backs, pregame testosterone (P =
3.6 × 10
–5
), T:C (P = .038), and postgame testosterone (P
= .045) concentrations were signicantly greater before
a win than a loss (Table 6). We found no signicant dif-
ferences between the forwards’ hormonal concentrations
(pregame, postgame, and perigame) across the different
match outcomes.
We found signicant correlations between pregame
testosterone concentration and game-ranked outcome
for both the team (r = .81, P = .049) and backs (r = .91,
P = .011; Figure 1). The pregame T:C for the backs was
the only other variable that correlated with game-ranked
outcomes (r = .81, P = .05—Figure 2).
Discussion
Our results suggest that differences seen in the pre-
game testosterone discriminate strongly between game
outcomes. This held across a more subjective, detailed
classication of game outcome.
Pregame testosterone as an indicator of team out-
come in sport has not, to our knowledge, been presented
previously. There is considerable literature from individ-
ual-based sport
11,13–16,24
linking the outcomes of games
and combat bouts (wrestling and judo) to testosterone
concentrations, generally across a single day of bouts
or a single game, but pregame testosterone is not well
presented as a predictive factor. “Snapshot” studies are
extremely difcult to interpret as testosterone shows very
large variability across time.
25
Our study was somewhat
unique in allowing us to follow the same team across 6
games, removing some of the noise associated with this
variability. The longitudinal approach taken in this study
allowed a more comprehensive understanding of pregame
testosterone relationships to game outcome, while also
testing the stability of these outcomes. Arguably this
Table 5 Comparison of Hormone
Concentrations According to Game Venue
(Home and Away), Mean (SD)
Measure Home Away
Pregame testosterone (pg/
mL) 104 (40) 103 (32)
Pregame cortisol (μg/dL)
0.3 (0.4) 0.3 (0.1)
Pregame T:C ratio
571 (326) 510 (292)
Postgame testosterone (pg/
mL) 140 (68) 171 (80)**
Postgame cortisol (μg/dL)
0.6 (0.3) 0.8 (0.5)***
Postgame T:C ratio
285 (164) 246 (131)
Perigame testosterone
1.6 (0.9) 1.8 (0.9)
Perigame cortisol
3.8 (3.9) 4.4 (4.8)
Perigame T:C ratio
0.7 (0.6) 0.6 (0.4)
Abbreviations: T:C = testosterone-to-cortisol. Note: Perigame = post-
game ÷ pregame hormone concentration.
Signicantly different from home: **P < .05, ***P < .01.
Table 6 Comparison of Salivary Hormones According to Outcome (Win or Loss) for All Games,
Mean (SD)
Team (N = 22) Backs (n = 11) Forwards (n = 11)
Measure Win Loss Win Loss Win Loss
Pregame testosterone (pg/mL) 115 (39)*** 91 (28) 127 (43)*** 86 (22) 112 (33) 97 (32)
Pregame cortisol (μg/dL)
0.3 (0.3) 0.2 (0.1) 0.5 (0.5) 0.3 (0.1) 0.2 (0.1) 0.2 (0.2)
Pregame T:C ratio 589 (316)* 491 (278) 552 (367) ** 390 (147) 614 (271) 575 (336)
Postgame testosterone (pg/mL) 161 (83) 149 (63) 164 (60)** 134 (46) 160 (99) 160 (74)
Postgame cortisol (μg/dL)
0.7 (0.4) 0.7 (0.4) 0.7 (0.3) 0.6 (0.3) 0.7 (0.5) 0.8 (0.4)
Postgame T:C ratio 277 (143) 257 (130) 258 (135) 273 (153) 294 (146) 244 (107)
Perigame testosterone 1.8 (1.0) 1.7 (0.8) 1.4 (0.6) 1.6 (0.6) 1.7 (1.3) 1.8 (0.9)
Perigame cortisol 4.1 (3.9) 4.1 (4.0) 3.9 (3.5) 2.8 (1.6) 4.2 (3.9) 5.3 (5.0)
Perigame T:C ratio 0.6 (0.5) 0.6 (0.4) 0.7 (0.6) 0.7 (0.4) 0.6 (0.3) 0.5 (0.4)
Abbreviations: T:C = testosterone-to-cortisol. Note: Perigame = postgame ÷ pregame hormone concentration.
Signicantly different from loss: *P < .1, **P < .05, ***P < .01.

328 Gaviglio et al
nding may be a peculiarity of this team and group of
individuals but certainly suggests merit in repeating this
across other teams.
There is reasonable rationale for using free testos-
terone as a pregame predictive tool. Individual variance
in free-testosterone concentrations has been linked to
aggressive and dominant behavior
9,14,15
and to the expres-
sion of maximal power and short-distance (time) speed.
6
Expressed across several individuals in a team, it is not
hard to speculate the advantages of these attributes in a
game of rugby. The pregame T:C also showed a moder-
ated correlation to game outcome, but this of course may
simply reect changes in testosterone concentrations and
the lack of statistical change in cortisol. Some studies
have suggested the use of T:C as a measure of recovery,
with a high T:C indicative of positive anabolic state
18
;
hence, speculatively, it is possible that a higher T:C in
the current study indicates that players’ recovery was
Figure 1 — Relationship between pregame (Pre) salivary testosterone and game-ranked outcome. Game-ranked outcome: 1 = bad
loss, 2 = unlucky loss, 4 = average win, 5 = good win, and 6 = good win +. Regression lines presented for the team, backs, and
forwards. Error bars represent standard error.
Figure 2 — Relationship between the pregame (Pre) salivary testosterone-to-cortisol (T/C) ratio and game-ranked outcome. Game-
ranked outcome: 1 = bad loss, 2 = unlucky loss, 4 = average win, 5 = good win, and 6 = good win +. Regression lines presented for
the team, backs, and forwards. Error bars represent standard error.

Testosterone and Competition Outcome 329
better before winning outcomes. The ability to recover
is of particular importance across a rugby season due to
the weekly exposures and extremely physical demands
of the sport.
Beyond the supporting role for testosterone in perfor-
mance, there are many other factors that are responsible
for outcome during a game (eg, refereeing decisions,
weather, skill execution, and opponents’ performance).
Home-versus-away hormonal data and historical statisti-
cal win/loss data did not show any causality on pregame
salivary hormones. Studies
26,27
have shown that playing
at home can offer both psychological and hormonal
advantages for some athletes when compared with an
opponent’s home ground. Further to this, it could be
plausible that the opposition team also inuenced the
anticipatory level of pregame testosterone, due to perfor-
mance expectations based on previous matches played.
However, we could not conclude from our results that
these specic factors had a direct effect on pregame levels
of salivary hormones, in particular, testosterone. The
players involved in this study were well-seasoned elite
athletes who at the time were a championship contending
team. The driving factors behind their success may have
been a collective and internal effort, thereby minimizing
external distractions detrimental to performance (eg,
game venue).
Such a theory, however, needs more investigation
across a larger number of games. This point highlights
that although hormone status of an athlete is important,
there are many other factors that contribute to game
outcome that may not be controllable. As such, pregame
measurement of free-testosterone concentration has
probability value but only among numerous other factors.
We saw no strong evidence to support an effect of
game outcome on perigame testosterone. This observation
is somewhat in contrast to ndings in other sports.
13–17
However, in those other sports the observation is complex
with dependencies on gender, situation of measurement,
team “culture,” and individual perceptions (eg, team
outcome vs individual perception of self-performance),
to name a few examples. Preliminary data (unpublished)
that we have collected suggest that the relationship of
testosterone changes (pregame to postgame) to game
outcome is team-culture dependent, being stronger in
teams that share strongly in the outcome rather than in
individual performance.
Examining the results by playing position (forwards
vs backs) gave some interesting additional observations.
Pregame testosterone concentrations and T:C in the backs
were the only hormonal measures to show signicance
to the game outcomes. Forwards showed no signicant
relationship between any game-day hormonal measure
and the outcomes. Initially these results surprised us,
considering the requirements of the game, given that
forwards are involved ostensibly in more contact and
aggressive situations than the backs.
2
The backs clearly
spend more time in free running at speed
2
but also in a
considerable degree of aggressive encounters and contact
at high speed,
28
and these ndings parallel a recent study
on elite rugby union players where the salivary testos-
terone concentrations of players, especially the backs,
correlated to speed, power, and strength.
6
We acknowledge that statistically only 6 games were
followed; however, the results seen in this study add to
those seen in other sporting contexts
13,14,16
and present the
novel nding of a strong relationship between pregame
testosterone concentrations and rugby outcome.
It is also important to acknowledge that the costs
of performing such an intensive and comprehensive
sampling collection are high, and this argues against the
use of hormones as a routine monitoring tool. We also
acknowledge the limitations of using saliva over blood
sampling to determine hormonal status. Although blood
samples are needed to substantiate the actual status of
gonadal function, elite athletes’ situation does not easily
allow the opportunity to obtain blood. On the other
hand, using saliva to analyze endogenous hormones
is noninvasive and stress-free.
29
Salivary testosterone
and cortisol concentration measures correlate well with
the blood hormones, especially the free hormone that
initiates the biological response at target tissue
23
and
the bioavailable hormone that is potentially available to
tissue.
30
So although we are not able to understand the
mechanism behind gonadal function under competitive
stress, we are still able to obtain valuable descriptive
data of elite athletes in real competitive situations. This
type of data is lacking in the current literature, and this
study helps provide that necessary rst step to understand
such responses.
In conclusion, this study presented a strong associa-
tion between concentrations of free testosterone before
games and actual game outcomes in professional rugby
players across 6 matches. Given that there are physical
and psychological methods by which free-testosterone
concentrations can be acutely elevated, it would be
interesting to see if an acute prematch change in testos-
terone could subsequently affect game performance and
outcome.
Practical Applications
The current ndings suggest a link between pregame free-
testosterone levels and success in an aggressive, contact-
based professional team sport. At present, the cost and
time to analyze pregame hormonal data are too high and
too slow, respectively, to suggest routine use. However,
examining how physical and psychological methods can
acutely alter prematch testosterone concentrations and
how training-week actions inuence it offers potential
avenues for managing performance on game week and
improving team readiness to compete on game day. In
addition, exploring the link between game-day T:C and
performance in rugby backs suggests that the monitor-
ing of training and game loads (eg, through the use of
global positioning system technology) and employment
of appropriate recovery techniques may also assist with
optimal game-day preparation.

330 Gaviglio et al
Acknowledgments
The authors declare that they have no conict of interest.
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