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A number of intermittent team sports require that two consecutive periods of play (lasting for ~30-45 min) are separated by a 10-20 min half-time break. The half-time practices employed by team-sports players generally include returning to the changing rooms, temporarily relaxing from the cognitive and physical demands of the first half, rehydration and re-fuelling strategies, addressing injury or equipment concerns, and receiving tactical instruction and coach feedback. However, the typically passive nature of these actions has been associated with physiological changes that impair performance during the second half. Both physical and cognitive performances have been found to decline in the initial stages of subsequent exercise that follows half-time. An increased risk of injury has also been observed during this period. Therefore, half-time provides sports scientists and strength and conditioning coaches with an opportunity to optimise second-half performance. An overview of strategies thought to benefit team-sports athletes is presented; specifically, the efficacy of heat maintenance strategies (including passive and active methods), post-activation potentiation, hormonal priming, and modified hydro-nutritional practices are discussed. A theoretical model of applying these strategies in a manner that compliments current practice is also offered.
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REVIEW ARTICLE
Half-Time Strategies to Enhance Second-Half Performance
in Team-Sports Players: A Review and Recommendations
Mark Russell Daniel J. West Liam D. Harper
Christian J. Cook Liam P. Kilduff
ÓSpringer International Publishing Switzerland 2014
Abstract A number of intermittent team sports require
that two consecutive periods of play (lasting for
*30–45 min) are separated by a 10–20 min half-time
break. The half-time practices employed by team-sports
players generally include returning to the changing rooms,
temporarily relaxing from the cognitive and physical
demands of the first half, rehydration and re-fuelling
strategies, addressing injury or equipment concerns, and
receiving tactical instruction and coach feedback. How-
ever, the typically passive nature of these actions has been
associated with physiological changes that impair perfor-
mance during the second half. Both physical and cognitive
performances have been found to decline in the initial
stages of subsequent exercise that follows half-time. An
increased risk of injury has also been observed during this
period. Therefore, half-time provides sports scientists and
strength and conditioning coaches with an opportunity to
optimise second-half performance. An overview of strate-
gies thought to benefit team-sports athletes is presented;
specifically, the efficacy of heat maintenance strategies
(including passive and active methods), post-activation
potentiation, hormonal priming, and modified hydro-
nutritional practices are discussed. A theoretical model of
applying these strategies in a manner that compliments
current practice is also offered.
Key Points
Passive half-time practices impair performance in
the initial stages of the second half of team-sports
competition.
The efficacy of heat maintenance strategies, post-
activation potentiation, hormonal priming, and
modified hydro-nutritional practices have been
shown in isolated studies.
1 Introduction
A number of intermittent team sports, such as Association
football (soccer), rugby league and union, Gaelic sports
(e.g. Gaelic football and hurling), team handball, field
hockey and Australian rules football are played over con-
secutive periods (normally 30–45 min durations) that are
separated by a temporary pause in play at the mid-way
point; a period known as half-time which is 10–20 min
long. While the regulations of the various sports dictate the
practices that can be performed during half-time, empirical
observations highlight that players primarily aim to relax
mentally from the cognitive and physical demands of the
first half of match-play, rehydrate and re-fuel, attend to
M. Russell (&)
Department of Sport, Exercise and Rehabilitation, Health and
Life Sciences, Northumbria University, Northumberland Street,
Newcastle-upon-Tyne NE1 8ST, UK
e-mail: mark.russell@northumbria.ac.uk
D. J. West L. D. Harper
Health and Life Sciences, Northumbria University,
Newcastle-upon-Tyne NE1 8ST, UK
C. J. Cook
School of Sport, Health and Exercise Sciences,
Bangor University, Bangor, UK
L. P. Kilduff
Applied Sports Technology Exercise and Medicine Research
Centre (A-STEM), Swansea University, Swansea, UK
123
Sports Med
DOI 10.1007/s40279-014-0297-0
injury or equipment concerns, engage in personal reflec-
tion, and receive tactical instruction and coach feedback in
preparation for the second half. Indeed, Towlson et al. [1]
reported that soccer players primarily return to the dressing
room to engage in tactical discussion, receive medical
treatment and consume nutritional ergogenic aids during
the half-time break.
However, during the initial stages of the second half,
numerous authors have reported that reductions in key
aspects of team-sport performance occur. For example,
Mohr et al. [2] showed that as many as 20 % of elite soccer
players have their least intense 15-min period in a match
during the initial part of the second half. Weston et al. [3]
also highlighted that selected physical performance mark-
ers of soccer players and referees decreased between 45
and 60 min when compared with the first 15 min of soccer
match-play. In respect to cognitive performance, as very
often success in team sports is determined by the profi-
ciency of skilled actions, the increase in response accuracy
observed during the first 30 min of intermittent exercise
was attenuated upon restarting exercise after half-time [4].
It therefore appears that half-time practices influence sub-
sequent performance during the initial stages of the second
half, a statement supported by intervention studies that
have demonstrated that attenuated losses in body temper-
ature lead to favourable responses in isolated performance
tests and game-related activities [5,6].
A significant increase in injury risk has also been
reported in the first 20 min of the second half [7]. Analysis
of ten Premier League soccer matches has highlighted that
of the injuries occurring in the second half, the greatest
number of actions causing injury were elicited in the first
15 min of this period [8]. Additionally, Ekstrand et al. [9]
have reported that the incidence of soccer-match injuries
show an increasing tendency over time in both the first and
second halves. Interestingly, the perception of increased
injury risk immediately after the half-time break is also
shared by practitioners involved in the delivery of half-time
activities for soccer players [1].
Factors contributing to increased injury risk are likely
multifaceted; however, Greig [10] reported that while the
concentric strength of both the knee extensors and flexors
was maintained throughout 90 min of intermittent tread-
mill running, a speed-dependent fatigue effect observed in
indices of eccentric hamstring strength did not normalise
during a passive half-time period. Specifically, when using
isokinetic dynamometry, eccentric peak torque measure-
ments taken after half-time were reduced when compared
with the start of the recovery period, a finding that was
statistically significant at higher movement speeds. As a
result, the authors postulated that susceptibility to muscular
strain injury is likely to increase during explosive ballistic
actions, such as those requiring high levels of acceleration
and deceleration. Notably, the number of deceleration
efforts performed in the first 15 min of the second half of
soccer match-play is lower than that observed during the
opening phase of a match [11].
Evidence from studies that have employed passive half-
time practices further highlight the subsequent impairments
of performance capacities observed throughout the second
half [3,5,6,1214]. Consequently, the physiological
changes relating to muscle (T
m
) and core (T
core
) tempera-
ture [6,1316], acid-base balance [17] and glycaemic
response [1820] which arise from passive periods com-
parable in length to those observed during half-time (i.e.
*15 min) may therefore contribute to a reduction in play
performance in the first part of the second half. Notably,
Krustrup et al. [21] observed a *1.3 °C reduction in
quadriceps T
m
during half-time in assistant soccer referees.
Although a desire to enforce tactical superiority [22] and
residual ergogenic effects resulting from the warm-up [23]
have been cited to artificially elevate the pace of play in the
initial stages of a match and thus influence subsequent
comparisons to observations made during this interval [12],
transient reductions in performance during the initial stages
of the second half have been confirmed using a more robust
statistical approach (i.e. when variables are expressed in
relative and thus comparable terms: mmin
-1
)[12]. It is
therefore clear that half-time provides an additional
opportunity on the day of competition to optimise perfor-
mance during the second half.
However, as time pressures, cooperation of the coach/
manager and concerns over impairing a player’s psycho-
logical preparations have been cited as barriers to the use of
specific ergogenic strategies during the half-time period
[1], it is clear that any modification to half-time protocols
must complement current practice. The time-course of
activities performed during a typical half-time period is
outlined in Fig. 1. Although likely to vary between dif-
ferent sports and according to individual team practices,
Towlson et al. [1] reported that *2 min of the soccer half-
time period consists of player’s making their way back to
the changing rooms. Thereafter, although tactical de-
briefing and medical and nutritional practices occupy the
most time (*5 min), personal preparation, addressing
playing kit/equipment concerns, receiving video feedback
and engaging in player/coach interactions also occur during
this break in play. Additionally, a *3-min period of re-
warm-up activities that are performed either on the pitch or
within the stadia may precede the second half of soccer
match-play [1].
In summary, although often considered crucial for pri-
marily tactical reasons, physiologically, half-time can be
viewed as a recovery period following the previous bout of
match-play, a preparatory period preceding subsequent
competition, or a period of transition between the two
M. Russell et al.
123
halves [24]. Given the transient changes in physical and
cognitive performance that have been found to occur fol-
lowing the half-time break [24,6,12,14], and the evi-
dence which suggests that the perception [1], and incidence
[7,8], of injury risk is elevated in the initial stages of the
second half, half-time provides an additional opportunity
on the day of a match to influence subsequent competitive
performance. Therefore, the purpose of this review was
twofold: (1) to present an overview of the literature
examining practices that may have application to the half-
time strategies of players involved in team sports; and (2)
to provide a theoretical model of application of such
strategies in the context of current practice. Computerised
literature searches were performed in the PubMed, Google
Scholar and SPORTDiscus databases between May 2014
and November 2014. The following keywords were used in
different combinations: ‘half time’, ‘recovery’, ‘soccer’,
‘football’, ‘rugby’, ‘handball’, ‘Gaelic’, ‘hockey’, ‘poten-
tiation’, ‘performance’, ‘hydration’, ‘carbohydrate’, ‘caf-
feine’, ‘priming’, ‘heat maintenance’, ’re-warm up’, ‘warm
up’, ‘testosterone’. All titles were scanned and relevant
articles were retrieved for review. In addition, the reference
lists from both original and review articles retrieved were
also reviewed and relevant publications known to the
authors were also obtained.
2 Half-Time Strategies to Enhance Second-Half
Performance in Team-Sports Players
2.1 Heat Maintenance Strategies
Nearly every athletic competition is preceded by a warm-
up. Typically, varying intensities of exercise, dynamic
stretching and technical practice are performed so that
preparedness for subsequent activity is optimised. While
the ergogenic effects of the warm-up have been proposed
to relate to non-temperature-related mechanisms (e.g. ele-
vated baseline oxygen consumption, post-activation
potentiation [PAP], increased mental preparedness, etc.
[25,26]), previous research also highlights the role of T
m
on performance.
Notably, Mohr et al. [6] observed initial elevations of
both T
m
and T
core
during the first half of a soccer match;
however, during a passive half-time period both T
m
and
T
core
dropped in excess of 1 °C. Sargeant [27] highlighted
the importance of changes in T
m
on subsequent perfor-
mance by demonstrating that every 1 °C reduction in T
m
corresponded to a 3 % reduction in lower-body power
output. Moreover, findings from studies reporting attenu-
ated losses of T
m
and concomitant protection of physical
performance in team-sports players following an active re-
warm-up [5,6,13] further substantiate the importance of
attenuating body temperature losses during half-time.
However, despite an acknowledgement that attenuating
losses in body temperature impact positively on subsequent
exercise performance, intermittent sports players do not
frequently use active re-warm up strategies in the applied
setting [1]. Indeed, despite periods of warm-up preceding
the first half of competition, only 58 % of practitioners
questioned have reported performing re-warm-up activities
before the second half, a finding that may be attributed to
the limited time (*3 min) available for such activities [1].
Furthermore, a lack of co-operation from the coach/man-
ager and a perceived negative impact upon the psycho-
logical preparations of players have also been proposed as
barriers to explain the inconsistent use of an active re-
warm-up during the half-time period. Additionally, in
sports such as rugby where the number of collisions is high,
considerable time may also be required for provision of
Fig. 1 Current model of strategies employed during a typical 15-min half-time period
Half-Time Strategies in Team Sports
123
medical attention at half-time. Therefore, half-time prac-
tices that are easily administered and which attenuate
temperature loss and thus protect the temperature-related
mechanisms that aid subsequent performance warrant fur-
ther investigation.
2.1.1 Passive Heat Maintenance Strategies
The use of specific methods (e.g. heated clothing, outdoor
survival jackets, and heating pads) which seek to attenuate
body temperature loss is known as passive heat mainte-
nance [28]. Such strategies are easily applied to the desired
muscle groups to maintain T
m
, and thus the temperature-
mediated pathways that aid performance [15]. For exam-
ple, repeated sprint performance and lower-body peak
power outputs were greater than observed in a control trial
when professional rugby union players wore a survival
garment during the post-warm-up recovery period [15].
Furthermore, the decline in lower-body peak power output
observed post-warm-up was significantly associated
(r=0.71) with the decline in T
core
[15].
In professional rugby union players who wore a survival
jacket during a simulated half-time period, muted losses of
T
core
(-0.74 ±0.08 % vs. -1.54 ±0.06 %) throughout
the 15-min period were observed versus a passive condition
[16]. The drop in T
core
over the simulated half-time was
significantly associated with reduced peak power output at
the start of subsequent exercise (r=0.63). In support of
previous authors [28,29], we proposed that the preserva-
tion of temperature-mediated pathways contributed to the
improved physical performances observed after the half-
time break.
Maintenance of T
m
during the half-time period is
therefore likely to attenuate decrements in subsequent
performance, especially during the initial stages of suc-
cessive exercise. Passive heat maintenance offers an
effective and practical method for preserving body tem-
perature, which helps to combat the decrements in per-
formance that may occur through the loss of T
m
.
However, further research into strategies that seek to
attenuate losses in body temperature and that have
application to team-sports players is warranted. Although
encouraging players to wear specific garments is recom-
mended and has proven beneficial [15,16,29], some
players (e.g. those receiving injury treatments) may find
this strategy restrictive when such clothing is worn during
half-time. Other methods of maintaining body temperature
during the half-time break should therefore be considered;
speculatively, the effects of increased changing-room
temperatures (within tolerable limits) may confer perfor-
mance advantages during subsequent exercise. However,
it is likely that modified hydration strategies are required
if such protocols are administered so that the potential
ergolytic effects resulting from impaired hydration status
are minimised.
2.1.2 Active Heat Maintenance Strategies (Half-Time Re-
Warm-Up)
Moderate-intensity running commencing after 7 min of a
half-time recovery period has been found to attenuate a
1.5 °C reduction in T
m
and protect the 2.4 % decrements in
mean sprint performance observed under passive control
conditions [6]. Moreover, the half-time decrease in T
m
was
correlated to the reduction in sprint performance observed
over half-time (r=0.60). Edholm et al. [5] reported sim-
ilar magnitudes of sprint performance maintenance and
attenuated losses in jump performance following a low-
intensity half-time re-warm-up. Additionally, intermittent
agility exercise, whole-body vibration, small-sided games
and lower-body resistance exercises performed during half-
time have been found to be beneficial [13,30].
Active re-warm-ups may also benefit skilled, as well as
physical, performances executed in the second half. For
example, 7 min of low-/moderate-intensity activity and
light calisthenics performed towards the end of half-time
improved performance during an actual match as less
defensive high-intensity running and more ball possession
was observed in the second half [5]. In support of the
findings of Edholm et al. [5], skilled performance during an
isolated technical assessment has also been reported to be
maintained when small-sided games incorporating skilled
actions are performed during a simulated half-time break
[30]. However, while active re-warm-ups appear beneficial,
consideration must be given to the duration of the activities
performed in the context of applied practice.
2.2 Post-Activation Potentiation
The ability of a muscle group to produce force can be
influenced by the previous contractive history of the same
muscle group [31]. The mechanisms of this transient
improvement in physical performance are suggested to
relate to enhanced motor neuron recruitment, a more
favourable central input to the motor neuron and/or an
enhanced Ca
2?
sensitivity of actin–myosin myofilaments
[32]. Despite a large body of evidence supporting the
ergogenic effects of a preload stimulus [33], not all studies
have demonstrated performance improvements as a num-
ber of factors modulate the PAP response (e.g. the strength
of the participant, volume and type of the preload stimulus,
and the duration of recovery between the preload stimulus
and subsequent activity) [32]. When considering the
potential application of PAP during the half-time period of
team sports, the type of activities performed and the timing
of the preload stimulus are likely to be of primary interest.
M. Russell et al.
123
2.2.1 Timing between the Preload Stimulus
and Subsequent Activity
Improved physical performance attributable to PAP fol-
lowing a preload stimulus is a function of both muscle
fatigue and potentiation that simultaneously co-exist.
Optimised recovery between the preload stimulus and the
subsequent exercise therefore favours an acute enhance-
ment of subsequent performance as the effects of potenti-
ation persist for longer than the effects of fatigue [34].
Additionally, the time demands associated with established
half-time practices (Fig. 1) are likely to influence the
decision of whether to recommend performing a preload
stimulus to team-sports players.
Between 0 and 24 min has previously been reported to
separate the conditioning exercise and the subsequent
explosive activity. Power output, peak rate of force
development and countermovement jump height were
significantly elevated above baseline values at 8 min of
recovery for the majority (i.e. 70 %) of professional rugby
players who performed repeated assessments (i.e. baseline,
*15 s and every 4 min) of explosive activity in the 24 min
following a preload stimulus (i.e. three sets of three repe-
titions at 87 % 1-repetition maximum [1RM] squat) [31], a
finding that has since been confirmed [33]. From a practical
perspective, the transient nature of the PAP response means
that the benefit to performance may be limited to the initial
stages of a player’s involvement in subsequent competi-
tion. However, this is the period whereby decrements in
performance attributable to passive practices have been
shown to be at their greatest [16].
From studies where heavy-resistance exercise has been
used to induce PAP, explosive lower-body power produc-
tion is consistently compromised immediately after the
preload stimulus [33]. Therefore, should practitioners
consider the use of PAP during half-time, the preload
stimulus should be timed relative to the start of match-play
in order to minimise the effects that a transient reduction in
performance may have upon subsequent competition.
2.2.2 Type of Preload Stimulus Performed
Heavy (i.e. 75–95 % 1RM) resistance exercise has been
used as the preload stimulus in the majority of studies
examining the PAP phenomenon [33]. However, at half-
time this approach may not be feasible as issues relating to
access to facilities at away venues has previously been
reported [1]. Methods of stimulating PAP that have less
equipment demands and/or may be better tolerated by
players and coaches on the day of competition provide
attractive alternatives. Notably, ballistic activities such as
weighted jumps are associated with the preferential
recruitment of type 2 motor units [35], and may therefore
be utilised as a PAP stimulus. Furthermore, plyometric
exercise has also been found to potentiate sprint perfor-
mance [36].
Using jumps performed against a resistance of 2 % body
mass (via a weighted vest) that were incorporated into a
dynamic warm-up, improved jumping performance has
subsequently been observed in the following 2 min [37].
Similarly, Chen et al. [38] reported improvements in
countermovement jump height following multiple sets of
depth jumps. Turner et al. [36] recently reported that
*75 s of alternate-leg bounding performed with (?10 %
body mass) and without (body mass only) a weighted vest,
potentiated subsequent sprint performance when compared
with a control trial. Notably, a greater enhancement of
sprint performance was observed in the body mass plus
10 % trial when compared with the body mass only trial,
and this increase was related to the baseline speed of
participants.
Practitioners may therefore wish to recommend plyo-
metric activities during the final stages of half-time to
enhance subsequent performance. Notably, the shorter
durations of PAP-inducing exercise are likely to be better
tolerated when compared with those typically used in
active re-warm-up studies (*7 min). However, consider-
ation should also be given to the fact that a transient
reduction in performance is commonly observed in the
immediate period (i.e. \3 min) following the preload
stimulus [33] and that the effects of PAP as a specific half-
time strategy have not been directly examined.
2.3 Hormonal Priming
High-intensity exercise can promote rapid changes in the
hormonal milieu postulated to benefit subsequent exercise
performance [39,40]. Indeed, in a workout performed
2 min after a short-duration (*40 s) maximal exercise
bout that elevated salivary testosterone concentrations,
improved strength performance was observed in profes-
sional rugby players [40]. Acute modification of the hor-
monal environment induced by the bout of sprint-cycle
exercise was reported to have contributed to the improve-
ment of subsequent exercise performance [40]. In support
of this finding, previous authors have observed improved
upper-body strength profiles following the systemic ele-
vation of endogenous hormones via prior lower-body
resistance exercise [41].
Interestingly, a number of authors have also reported
that the content of videos watched prior to exercise can
influence hormonal responses and subsequent physical
performance. For example, in professional rugby players,
Cook and Crewther [42] observed improvements in squat
strength 15 min after watching short (4 min) video clips
that included aggressive, training, erotic or humorous
Half-Time Strategies in Team Sports
123
content. Notably, the aggressive video caused significant
increases in salivary testosterone that exceeded all other
video types and improved squat performance more so than
either the erotic or humorous clips. Moreover, viewing
footage 75 min before a match that showed successful skill
executions performed by an athlete, which was reinforced
with positive coach feedback, promoted the highest pre-
game testosterone concentrations and best subsequent
performance ratings [43]. Conversely, presenting footage
of successful skill executions of opposing players while
providing cautionary coach feedback, induced an enhanced
stress response [43].
While the direct effect of specific hormonal priming
strategies administered during the half-time break have not
yet been examined, and assuming that the relationships
between pre-match testosterone concentrations and match
performance [44] remain true, it is plausible that strategies
which elevate free testosterone employed during the half-
time break may improve subsequent match performance.
As shown in Fig. 1, half-time often includes a period of
tactical instruction, be it either individual or team-based,
which may utilise video playback [1]. Therefore, modifi-
cation of the footage and feedback presented to the players
may offer a simple strategy to improve subsequent per-
formance. Furthermore, high-intensity exercise, perhaps
used as part of a half-time re-warm-up, may also optimise
the hormonal milieu that contributes to improved exercise
performance thereafter.
2.4 Carbohydrate Consumption
When soccer has been used as the modality of exercise,
numerous authors have reported that muscle glycogen
concentrations reduce throughout both simulated and
actual match-play [45,46]. Consequently, team-sports
players are often encouraged to acutely consume carbo-
hydrates on the day of competition. Such recommendations
usually include guidance to ingest carbohydrates in the
hours before exercise, throughout competition and during
breaks in play, such as at half-time [47]. The proposed
mechanisms of ingesting carbohydrates relate to an effort
to spare muscle glycogen and to maintain blood glucose
concentrations for the duration of a match [4850]. How-
ever, the physiological response to carbohydrates con-
sumed during exercise, such as a match, differs to that
observed when carbohydrates are consumed in the non-
exercising state [51], similar to half-time.
Under normal physiological conditions, ingesting car-
bohydrates that increase blood glucose concentrations in a
passive state elicits an increase in insulin synthesis and
secretion from the bcells of the islets of Langerhans.
Insulin, in an attempt to normalize blood glucose concen-
trations, subsequently decreases lipolysis and increases
glucose uptake in liver, skeletal muscle and fat cells [51].
Conversely, hyperglycaemic responses are observed during
high-intensity exercise by the actions of counter-regulatory
hormones, including catecholamines, cortisol and growth
hormone [51]. Given the pattern of competitive match-play
in team-sports competition, it is surprising that the influ-
ence of carbohydrate supplementation on the glycaemic
response to a bout of exercise that is completed after a
period of recovery from a previous bout of exercise has
received little attention.
Ingestion of a 6 % sucrose-electrolyte beverage before
(i.e. within 2 h of commencing exercise and within 5 min
of starting each half) and during (i.e. every 15 min of
exercise) simulated soccer-specific exercise attenuated a
reduction in post-exercise shooting performance (assessed
during an isolated soccer skills test) [19]. However, in
support of data reported by Bangsbo et al. [52], exogenous
carbohydrate provision before and during soccer-specific
exercise reduced blood glucose concentrations during the
initial stages of the second half by *30 %, a finding that
has since been confirmed in both simulated and actual
soccer match-play [18,20]. Most likely, this exercise-
induced rebound glycaemic response is explained by the
previously active muscles increasing glucose uptake, low-
ered catecholamine concentrations, and reduced stimula-
tion of liver glycogenolysis at the start of the second half
[52].
It appears that cerebral glucose availability is
impaired when blood glucose concentrations fall below
3.6 mmolL
-1
[53], and cognitive performance decre-
ments occur when blood glucose concentrations fall
below 3.4 mmolL
-1
[5463], concentrations that rep-
resent those previously reported in soccer players [20,
64]. As the quality of cognitive and physical perfor-
mances executed during and after soccer-specific exer-
cise appear to be influenced by changes in blood
glucose concentrations, strategies that maintain glyca-
emia for the full duration of match-play represent an
opportunity to achieve maximum soccer performance. A
number of factors, including the glycaemic index of the
carbohydrate consumed, timing of consumption and the
dose consumed, are likely to modulate the efficacy of
carbohydrates consumed on the day of competition [65].
In this review we present an overview of studies that
have application to these factors in the context of the
half-time break.
2.4.1 Glycaemic Index
Commercially-available sports drinks generally tend to
consist of between 6 and 10 % concentrations of high-
glycaemic index carbohydrates (e.g. maltodextrin).
Ingesting high-glycaemic index carbohydrates while in a
M. Russell et al.
123
non-exercising state, such as that observed during the ini-
tial phases of half-time, results in rapid increases in post-
prandial blood glucose concentrations. However,
consumption of high-glycaemic index carbohydrates in the
hour before exercise has also been reported to lower blood
glucose concentrations 15–30 min after starting subsequent
activity [55,66], a response attributed to free fatty acid
inhibition which increases carbohydrate usage throughout
isolated exercise bouts performed soon after carbohydrate
ingestion [55].
As highlighted in Sect. 2.4, we have consistently
reported that consuming sucrose-electrolyte beverages
before, and throughout, simulated soccer match-play
caused transient reductions in blood glucose concentrations
in the initial stages of the second half of soccer-specific
exercise [19,20,67]. However, low glycaemic index car-
bohydrates prolong the delivery of glucose to the systemic
circulation. Indeed, mean and peak oxidation rates of iso-
maltulose have been reported to be 50 and 42 % lower than
the oxidation rates of sucrose, respectively, when ingested
at the same rate (1.1 gmin
-1
)[68]. Although the effects of
different glycaemic index carbohydrates consumed during
the half-time period remain to be examined, it is plausible
that a reduced rate of digestion and absorption of low-
glycaemic index carbohydrates prolongs blood glucose
concentrations that have typically been found to decline in
the second half of intermittent activity.
2.4.2 Timing of Ingestion
Consistent evidence provided from studies requiring that
carbohydrates are consumed before a single bout of exer-
cise demonstrate that the timing of pre-exercise carbohy-
drate ingestion can influence subsequent metabolic
responses. For example, Moseley et al. [69] investigated
the metabolic response to 75 g of glucose ingested 15, 45
or 75 min before exercise. Plasma glucose and insulin
concentrations were significantly elevated immediately
before exercise in the 15-min feeding group, whereas the
lowest insulin concentrations were observed when carbo-
hydrate was ingested 75 min before exercise. Similarly,
ingestion of a 20 % fructose solution 15 min before the
second half of an intermittent cycling protocol resulted in
reductions in blood glucose concentrations compared with
pre half-time values for 40 min of the second half [24].
Consequently, the timing of carbohydrate ingestion during
the half-time period has the potential to influence respon-
ses; however, no studies have systematically examined the
influence of modifying the timing of carbohydrates pro-
vided during half-time in soccer players.
2.4.3 Dose Consumed
In studies that have employed continuous exercise proto-
cols and have focused on water absorption as a priority, the
detrimental effects observed on gastric emptying and
intestinal absorption have led to recommendations that
beverages containing between 5 and 8 % carbohydrates are
consumed during exercise [68,70,71]. However, when
intermittent exercise is performed, limited data currently
exist about the effects of providing additional carbohy-
drates (9 % solutions). Notably, ingestion of a 20 % glu-
cose solution has been reported to enhance sprint capacity
after 90 min of intermittent cycling [24], and a dose-
dependent relationship exists between the amount of car-
bohydrate consumed and indices of cognitive function in
non-exercising participants [72].
In recreational soccer players, greater blood glucose
concentrations have been observed from 75 min onwards
relative to a fluid–electrolyte placebo when a 9.6 % car-
bohydrate–electrolyte beverage was consumed before and
during (including at half-time) a simulated soccer match
[18]. Interestingly, differences in glycaemic responses were
observed despite similarities in blood glucose concentra-
tions between conditions at the 60 min time point
(*4.0 mmolL
-1
). As the pre-exercise carbohydrate dos-
age appears to elicit similar glycaemic responses [68,73],
and that the rebound hypoglycaemic response appears to
decay within the initial stages of exercise when high-gly-
caemic index carbohydrates are consumed [24,69], it is
plausible that provision of additional carbohydrates at half-
time may afford ergogenic effects in the latter stages of a
match; however, this remains to be confirmed.
2.4.4 Interactions between Carbohydrate Ingestion
and a Half-Time Re-Warm-Up
It is well established that high-intensity exercise can elicit a
hyperglycaemic response in both clinical and non-clinical
populations. An exercise-induced catecholamine release
inhibits pancreatic b-cell activity [74]; therefore, elevated
blood glucose concentrations result from exogenous car-
bohydrate provision during exercise. It is therefore plau-
sible that a combination of high-intensity exercise
performed during the half-time period, as well as simul-
taneous carbohydrate ingestion, could feasibly maintain
blood glucose concentrations thereafter. In support of this,
Achten et al. [68] observed that ingestion of 600 ml of a
concentrated maltodextrin drink consumed during a 25-min
cycle warm-up that included isolated sprint bouts,
increased catecholamine concentrations, blunted the insulin
Half-Time Strategies in Team Sports
123
response and actually increased blood glucose concentra-
tions at the onset of exercise. Although reductions in blood
glucose concentrations were observed after 20 min of
subsequent continuous exercise, these differences were
non-significant. Consequently, a half-time re-warm-up that
includes a high-intensity component, combined with the
ingestion of carbohydrates, may prove beneficial for team-
sports players who experience an exercise-induced rebound
glycaemic response. However, this is yet to be determined
when carbohydrates are provided during recovery from
previous activity and when the exercise performed is
intermittent in nature.
2.4.5 Carbohydrate Mouth Rinsing
Mouth-rinsing carbohydrate solutions can positively influ-
ence the perception of effort during subsequent exercise
and facilitate peak power output during the initial stages of
repeated sprint tests [75,76]. The mechanisms proposed
relate to the excitation of reward and motor control centres
in the brain [77] and an enhanced corticomotor pathway
excitability [78] induced by oral receptor stimulation.
Whether the presence of carbohydrate in the mouth can
facilitate improvements in subsequent performance when
used as a half-time strategy remains to be investigated;
however, the benefits of mouth swilling observed during
exercise provide a rationale for using this strategy at half-
time.
2.5 Caffeine Consumption
The ergogenic effects of caffeine (a central nervous system
stimulant) in team-sport athletes have been proposed to
relate to the attenuation of fatigue-related decrements in
skilled performances, concentration or cognitive function
as opposed to enhanced endurance capacity [79]. With
respect to soccer skill performance, the efficacy of caffeine
is unclear [65] despite the mean sprinting performances of
recreational players being improved when doses of
6mgkg
-1
body mass were co-ingested with
142 ±3gh
-1
of carbohydrate [18]. Additionally, the
mean performance of rugby passes made during an isolated
technical test over the duration of a simulated match was
improved when caffeine was ingested [80]. Therefore,
caffeine consumed during half-time may be efficacious for
subsequent performance.
When considering whether to recommend caffeine use
during half-time, the time-course of peak systemic con-
centrations of caffeine and/or its metabolites following
acute ingestion is likely to be of interest to practitioners.
Whether caffeine is consumed in either the fed or fasted
state appears to influence the rate of subsequent appearance
in the circulation [71]. Nevertheless, when the mechanisms
of action are reliant upon absorption via the lower gastro-
intestinal tract, peak concentrations of caffeine and/or its
metabolites are generally realised within 1 and 3 h of
ingestion. However, the efficacy of drug administration has
been proposed to be related to its speed of absorption [81]
and the ergogenic effects of caffeine have also been
attributed to the antagonism of receptors in the upper
gastrointestinal tract facilitating a central modulation of
motor unit activity and adenosine receptor stimulation [82].
In the last decade, caffeinated chewing gums have
become commercially available and have been associated
with significantly faster absorption times when compared
with a traditional pill-based administration modality [83].
For example, Ryan et al. [81] have recently observed
improved cycling performance when caffeinated gum
containing 300 mg of caffeine was provided 5 min before
exercise. Interestingly, providing the same dose of caffei-
nated gum 60 and 120 min prior to the start of exercise
negated the ergogenic effects observed. Despite very few
studies having investigated the effects of this novel method
of caffeine delivery, early evidence suggests that caffei-
nated gum may benefit the performance of intermittent
team-sports players. Furthermore, the time-course of
effects of action of caffeinated gums mean that they could
plausibly be consumed during half-time.
3 Model of Theoretical Application
As reviewed, the transition from a period of exercise to rest
and back to exercise replicates the general demands of a
number of team sports. This pattern of activity induces a
number of physiological effects that appear to influence
performance during subsequent exercise. Notably,
impaired performance has been observed during the initial
stages of the second half. Therefore, when seeking to
optimise performance throughout the full duration of
competition, half-time is an opportunity to employ specific
strategies that seek to maintain performance throughout the
second half.
However, the match-day practices of professional teams
are often very structured and rigid in nature. It is therefore
important that any proposed modification to the half-time
period seeks to complement, rather than replace, existing
protocols. Therefore, practical recommendations concern-
ing the implementation of such strategies may be beneficial
for the sports scientist and/or strength and conditioning
coach. In this review we present a theoretical model of
organising a 15-min half-time period to incorporate both
the practices currently employed and the strategies that we
have proposed to acutely enhance performance (Fig. 2).
While this proposed theoretical model may appear quite
complex, applied practitioners are encouraged to interpret
M. Russell et al.
123
our recommendations within the context of the require-
ments of their specific sports. Speculatively, these recom-
mendations may also have application outside of the
context of the half-time break as some sports (e.g. rugby
league) allow rolling interchanges and therefore players
may experience extended breaks in play between consec-
utive match involvements.
In order to attenuate the losses in body temperature
observed during the half-time break, strategies that seek to
maintain temperature-mediated pathways [15] should be
considered. Heated clothing, outdoor survival jackets and
heating pads can be applied with relatively little inconve-
nience to athletes, and have proved beneficial when seeking
to attenuate reductions in performance attributable to T
m
loss [15,16,29]. Furthermore, an increased changing-room
temperature may also prove worthwhile; however, this
remains to be explored.
At some point throughout half-time, individualised
footage of successful player skill executions supported by
affirmative positive cues from a coach may also benefit a
player’s subsequent performance [43]. However, it should
be noted that if such videos focus upon the successful skill
executions of opposing players while cautionary coach
feedback is provided, an enhanced stress response can be
observed [43]. Furthermore, acute bouts of high-intensity
exercise may prove beneficial in terms of priming the sys-
temic hormonal environment for subsequent exercise [40].
Active re-warm-ups administered in the final stages of
half-time improve subsequent physical and technical per-
formance by attenuation of the reductions in body tem-
perature seen when passive half-time practices are
performed [5,6,13,14]. As PAP has been observed fol-
lowing short-duration plyometric activities [36], such
exercises, when used as part of a re-warm-up strategy, may
serve as a time-efficient method of improving subsequent
performance.
Due to the mechanisms of action, the presence of caf-
feine and carbohydrate in the mouth has been found to
facilitate motor output and improve subsequent exercise
[76,81]. However, based upon literature examining the
efficacy of caffeine, if the duration between ingestion and
subsequent exercise is prolonged, the ergogenic effects of
these substances can be lost [81]. Therefore, within the
final stages preceding the restart of competition, the pro-
vision of caffeinated gum (with subsequent expectoration
before competition recommences) and carbohydrate solu-
tions (for the purposes of mouth swilling) should be con-
sidered (Fig. 2).
Finally, when seeking to minimise perturbations in
blood glucose concentrations that have consistently been
observed when recommencing the second half of exercise,
it is plausible that half-time strategies relating to the con-
sumption of exogenous energy (i.e. carbohydrates) could
be optimised by modifying the glycaemic index of the
beverage consumed, the timing of ingestion, the amount of
carbohydrate consumed and/or by combining ingestion
with a half-time re-warm-up. Therefore, consideration of
these factors should be given, especially in players deemed
to be susceptible to reduced blood glucose concentrations
upon restarting exercise.
Fig. 2 Theoretical model of strategies suggested during a 15-min half-time period
Half-Time Strategies in Team Sports
123
4 Conclusion
Periods of reduced activity between successive exercise
bouts have been found to influence an array of physio-
logical responses. Furthermore, reduced physical and
cognitive performance, as well as increased risk of injury,
have been identified in the initial stages of the second half
of team-sport competition. Therefore, the support of pre-
vious authors for the use of heat maintenance strategies,
half-time re-warm-ups (including actions to induce PAP),
hormonal priming, and caffeine and carbohydrate con-
sumption means that a method which combines a number
of these strategies for use on the day of competition may be
of interest to sports scientists and strength and conditioning
coaches involved with team sports. In addition to
appraising the evidence of these isolated strategies, we
have presented a practical model that allows combination
of a number of interventions that could theoretically elicit
additive effects over the use of such strategies in isolation.
However, given the differences that exist between sports in
half-time regulations (e.g. duration of break, access to
pitch, etc.), and players’ normal practices, we recommend
that the model is interpreted with considerable flexibility,
and we acknowledge that some adjustment is likely
dependent upon the players involved.
Acknowledgments No sources of funding were used to assist in the
preparation of this review. The authors have no potential conflicts of
interest that are directly relevant to the content of this review.
References
1. Towlson C, Midgley AW, Lovell R. Warm-up strategies of
professional soccer players: practitioners’ perspectives. J Sports
Sci. 2013;31(13):1393–401.
2. Mohr M, Krustrup P, Bangsbo J. Fatigue in soccer: a brief review.
J Sports Sci. 2005;23(6):593–9.
3. Weston M, Batterham AM, Castagna C, et al. Reduction in
physical match performance at the start of the second half in elite
soccer. Int J Sports Physiol Perform. 2011;6(2):174–82.
4. Greig M, Marchant D, Lovell R, et al. A continuous mental task
decreases the physiological response to soccer-specific intermit-
tent exercise. Br J Sports Med. 2007;41(12):908–13.
5. Edholm P, Krustrup P, Randers MB. Half-time re-warm up
increases performance capacity in male elite soccer players.
Scand J Med Sci Sports. Epub 30 Apr 2014.
6. Mohr M, Krustrup P, Nybo L, et al. Muscle temperature and
sprint performance during soccer matches: beneficial effect of re-
warm-up at half-time. Scand J Med Sci Sports. 2004;14(3):
156–62. doi:10.1111/j.1600-0838.2004.00349.x.
7. Hawkins RD, Fuller CW. Risk assessment in professional foot-
ball: an examination of accidents and incidents in the 1994 World
Cup finals. Br J Sports Med. 1996;30(2):165–70.
8. Rahnama N, Reilly T, Lees A. Injury risk associated with playing
actions during competitive soccer. Br J Sports Med. 2002;36(5):
354–9.
9. Ekstrand J, Hagglund M, Walden M. Injury incidence and injury
patterns in professional football: the UEFA injury study. Br J
Sports Med. 2011;45(7):553–8.
10. Greig M. The influence of soccer-specific fatigue on peak is-
okinetic torque production of the knee flexors and extensors. Am
J Sports Med. 2008;36(7):1403–9.
11. Russell M, Sparkes W, Northeast J et al. Changes in acceleration
and deceleration capacity throughout professional soccer match-
play. J Strength Cond Res. (In press).
12. Lovell R, Barrett S, Portas M, et al. Re-examination of the post
half-time reduction in soccer work-rate. J Sci Med Sport.
2013;16(3):250–4.
13. Lovell R, Midgley A, Barrett S, et al. Effects of different half-
time strategies on second half soccer-specific speed, power and
dynamic strength. Scand J Med Sci Sports. 2013;23(1):105–13.
doi:10.1111/j.1600-0838.2011.01353.x.
14. Lovell RJ, Kirke I, Siegler J, et al. Soccer half-time strategy
influences thermoregulation and endurance performance. J Sports
Med Phys Fitness. 2007;47(3):263–9.
15. Kilduff LP, West DJ, Williams N, et al. The influence of passive
heat maintenance on lower body power output and repeated sprint
performance in professional rugby league players. J Sci Med
Sport. 2013;16(5):482–6. doi:10.1016/j.jsams.2012.11.889.
16. Russell M, West DJ, Briggs MA, et al. A passive heat mainte-
nance strategy implemented during a simulated half-time
improves lower body power output and repeated sprint ability in
professional Rugby Union players. PLOS One (in press).
17. Russell M, Kingsley MI. Changes in acid-base balance during
simulated soccer match play. J Strength Cond Res. 2012;26(9):
2593–9.
18. Kingsley M, Penas-Ruiz C, Terry C, et al. Effects of carbohy-
drate-hydration strategies on glucose metabolism, sprint perfor-
mance and hydration during a soccer match simulation in
recreational players. J Sci Med Sport. 2014;17(2):239–43.
19. Russell M, Benton D, Kingsley M. Influence of carbohydrate
supplementation on skill performance during a soccer match
simulation. J Sci Med Sport. 2012;15(4):348–54. doi:10.1016/j.
jsams.2011.12.006.
20. Russell M, Benton D, Kingsley M. Carbohydrate ingestion before
and during soccer match play and blood glucose and lactate
concentrations. J Athl Train. 2014;49(4):447–53.
21. Krustrup P, Mohr M, Bangsbo J. Activity profile and physio-
logical demands of top-class soccer assistant refereeing in rela-
tion to training status. J Sports Sci. 2002;20(11):861–71.
22. Weston M, Drust B, Gregson W. Intensities of exercise during
match-play in FA Premier League referees and players. J Sports
Sci. 2011;29(5):527–32.
23. Russell M, Rees G, Kingsley MI. Technical demands of soccer
match play in the English championship. J Strength Cond Res.
2013;27(10):2869–73. doi:10.1519/JSC.0b013e318280cc13.
24. Sugiura K, Kobayashi K. Effect of carbohydrate ingestion on
sprint performance following continuous and intermittent exer-
cise. Med Sci Sports Exerc. 1998;30(11):1624–30.
25. Bishop D. Warm up I: potential mechanisms and the effects of
passive warm up on exercise performance. Sports Med.
2003;33(6):439–54.
26. Bishop D. Warm up II: performance changes following active
warm up and how to structure the warm up. Sports Med.
2003;33(7):483–98.
27. Sargeant AJ. Effect of muscle temperature on leg extension force
and short-term power output in humans. Eur J Appl Physiol
Occup Physiol. 1987;56(6):693–8.
28. West DJ, Dietzig BM, Bracken RM, et al. Influence of post-
warm-up recovery time on swim performance in international
M. Russell et al.
123
swimmers. J Sci Med Sport. 2013;16(2):172–6. doi:10.1016/j.
jsams.2012.06.002.
29. Cook C, Holdcroft D, Drawer S, et al. Designing a warm-up
protocol for elite bob-skeleton athletes. Int J Sports Physiol
Perform. 2013;8(2):213–5.
30. Zois J, Bishop D, Fairweather I, et al. High-intensity re-warm-ups
enhance soccer performance. Int J Sports Med. 2013;34(9):
800–5. doi:10.1055/s-0032-1331197.
31. Kilduff LP, Owen N, Bevan H, et al. Influence of recovery time
on post-activation potentiation in professional rugby players.
J Sports Sci. 2008;26(8):795–802. doi:10.1080/026404107017
84517.
32. Tillin NA, Bishop D. Factors modulating post-activation poten-
tiation and its effect on performance of subsequent explosive
activities. Sports Med. 2009;39(2):147–66. doi:10.2165/00007
256-200939020-00004.
33. Gouvea AL, Fernandes IA, Cesar EP, et al. The effects of rest
intervals on jumping performance: a meta-analysis on post-acti-
vation potentiation studies. J Sports Sci. 2013;31(5):459–67.
doi:10.1080/02640414.2012.738924.
34. Hamada T, Sale DG, MacDougall JD, et al. Interaction of fibre
type, potentiation and fatigue in human knee extensor muscles.
Acta Physiol Scand. 2003;178(2):165–73. doi:10.1046/j.1365-
201X.2003.01121.x.
35. Desmedt JE, Godaux E. Ballistic contractions in man: charac-
teristic recruitment pattern of single motor units of the tibialis
anterior muscle. J Physiol. 1977;264(3):673–93.
36. Turner AP, Bellhouse S, Kilduff L et al. Post-activation poten-
tiation of sprint acceleration performance using plyometric
exercise. J Strength Cond Res. Epub 2 Sep 2014.
37. Faigenbaum AD, McFarland JE, Schwerdtman JA, et al.
Dynamic warm-up protocols, with and without a weighted vest,
and fitness performance in high school female athletes. J Athl
Train. 2006;41(4):357–63.
38. Chen ZR, Wang YH, Peng HT, et al. The acute effect of drop
jump protocols with different volumes and recovery time on
countermovement jump performance. J Strength Cond Res.
2013;27(1):154–8. doi:10.1519/JSC.0b013e3182518407.
39. Goto K, Ishii N, Kurokawa K, et al. Attenuated growth hormone
response to resistance exercise with prior sprint exercise. Med Sci
Sports Exerc. 2007;39(1):108–15.
40. Crewther BT, Cook CJ, Lowe TE, et al. The effects of short-cycle
sprints on power, strength, and salivary hormones in elite rugby
players. J Strength Cond Res. 2011;25(1):32–9.
41. Hansen S, Kvorning T, Kjaer M, et al. The effect of short-term
strength training on human skeletal muscle: the importance of
physiologically elevated hormone levels. Scand J Med Sci Sports.
2001;11(6):347–54.
42. Cook CJ, Crewther BT. Changes in salivary testosterone con-
centrations and subsequent voluntary squat performance follow-
ing the presentation of short video clips. Horm Behav.
2012;61(1):17–22. doi:10.1016/j.yhbeh.2011.09.006.
43. Cook CJ, Crewther BT. The effects of different pre-game motiva-
tional interventions on athlete free hormonal state and subsequent
performance in professional rugby union matches. Physiol Behav.
2012;106(5):683–8. doi:10.1016/j.physbeh.2012.05.009.
44. Gaviglio CM, Crewther BT, Kilduff LP, et al. Relationship
between pregame concentrations of free testosterone and outcome
in rugby union. Int J Sports Physiol Perform. 2014;9(2):324–31.
45. Bendiksen M, Bischoff R, Randers MB, et al. The Copenhagen
Soccer Test: physiological response and fatigue development.
Med Sci Sports Exerc. 2012;44(8):1595–603.
46. Krustrup P, Mohr M, Steensberg A, et al. Muscle and blood
metabolites during a soccer game: implications for sprint per-
formance. Med Sci Sports Exerc. 2006;38(6):1165–74.
47. Williams C, Serratosa L. Nutrition on match day. J Sports Sci.
2006;24(7):687–97.
48. Convertino VA, Armstrong LE, Coyle EF, et al. American Col-
lege of Sports Medicine position stand. Exercise and fluid
replacement. Med Sci Sports Exerc. 1996;28(1):1–7.
49. Coyle EF. Fluid and fuel intake during exercise. J Sports Sci.
2004;22(1):39–55. doi:10.1080/0264041031000140545.
50. Coyle EF, Montain SJ. Carbohydrate and fluid ingestion during
exercise: are there trade-offs? Med Sci Sports Exerc. 1992;24(6):
671–8.
51. Astrand P-O, Rodahl K. Textbook of work physiology: physio-
logical bases of exercise. New York: McGraw-Hill; 1986.
52. Bangsbo J, Iaia FM, Krustrup P. Metabolic response and fatigue
in soccer. Int J Sports Physiol Perform. 2007;2(2):111–27.
53. Boyle PJ, Nagy RJ, O’Connor AM, et al. Adaptation in brain
glucose uptake following recurrent hypoglycemia. Proc Natl
Acad Sci U S A. 1994;91(20):9352–6.
54. Stevens AB, McKane WR, Bell PM, et al. Psychomotor perfor-
mance and counterregulatory responses during mild hypoglyce-
mia in healthy volunteers. Diabetes Care. 1989;12(1):12–7.
55. Costill D, Coyle E, Dalsky G, et al. Effects of elevated plasma
FFA and insulin on muscle glycogen usage during exercise.
J Appl Physiol. 1977;43:695–9.
56. Maran A, Crepaldi C, Trupiani S, et al. Brain function rescue
effect of lactate following hypoglycaemia is not an adaptation
process in both normal and type I diabetic subjects. Diabetologia.
2000;43(6):733–41.
57. Maran A, Lomas J, Macdonald IA, et al. Lack of preservation of
higher brain function during hypoglycaemia in patients with
intensively-treated IDDM. Diabetologia. 1995;38(12):1412–8.
58. Fanelli C, Pampanelli S, Epifano L, et al. Relative roles of insulin
and hypoglycaemia on induction of neuroendocrine responses to,
symptoms of, and deterioration of cognitive function in hypo-
glycaemia in male and female humans. Diabetologia. 1994;37(8):
797–807.
59. Fanelli C, Pampanelli S, Epifano L, et al. Long-term recovery
from unawareness, deficient counterregulation and lack of cog-
nitive dysfunction during hypoglycaemia, following institution of
rational, intensive insulin therapy in IDDM. Diabetologia.
1994;37(12):1265–76.
60. Widom B, Simonson DC. Glycemic control and neuropsycho-
logic function during hypoglycemia in patients with insulin-
dependent diabetes mellitus. Ann Intern Med. 1990;112(12):
904–12.
61. Fanelli CG, Epifano L, Rambotti AM, et al. Meticulous preven-
tion of hypoglycemia normalizes the glycemic thresholds and
magnitude of most of neuroendocrine responses to, symptoms of,
and cognitive function during hypoglycemia in intensively trea-
ted patients with short-term IDDM. Diabetes. 1993;42(11):
1683–9.
62. Veneman T, Mitrakou A, Mokan M, et al. Effect of hyperketo-
nemia and hyperlacticacidemia on symptoms, cognitive dys-
function, and counterregulatory hormone responses during
hypoglycemia in normal humans. Diabetes. 1994;43(11):1311–7.
63. Holmes CS, Koepke KM, Thompson RG, et al. Verbal fluency
and naming performance in type I diabetes at different blood
glucose concentrations. Diabetes Care. 1984;7(5):454–9.
64. Ekblom B. Applied physiology of soccer. Sports Med. 1986;3(1):
50–60.
65. Russell M, Kingsley M. The efficacy of acute nutritional inter-
ventions on soccer skill performance. Sports Med. 2014;44(7):
957–70.
66. Chryssanthopoulos C, Hennessy LC, Williams C. The influence
of pre-exercise glucose ingestion on endurance running capacity.
Br J Sports Med. 1994;28(2):105–9.
Half-Time Strategies in Team Sports
123
67. Russell M, Kingsley M. Influence of exercise on skill proficiency
in soccer. Sports Med. 2011;41(7):523–39. doi:10.2165/
11589130-000000000-00000.
68. Achten J, Jentjens RL, Brouns F, et al. Exogenous oxidation of
isomaltulose is lower than that of sucrose during exercise in men.
J Nutr. 2007;137(5):1143–8.
69. Moseley L, Lancaster GI, Jeukendrup AE. Effects of timing of
pre-exercise ingestion of carbohydrate on subsequent metabolism
and cycling performance. Eur J Appl Physiol. 2003;88(4–5):
453–8. doi:10.1007/s00421-002-0728-8.
70. Schedl HP, Maughan RJ, Gisolfi CV. Intestinal absorption during
rest and exercise: implications for formulating an oral rehydration
solution (ORS). Proceedings of a roundtable discussion. April
21–22, 1993. Med Sci Sports Exerc. 1994;26(3):267–80.
71. Skinner TL, Jenkins DG, Folling J, et al. Influence of carbohy-
drate on serum caffeine concentrations following caffeine
ingestion. J Sci Med Sport. 2013;16(4):343–7. doi:10.1016/j.
jsams.2012.08.004.
72. Messier C, Pierre J, Desrochers A, et al. Dose-dependent action
of glucose on memory processes in women: effect on serial
position and recall priority. Brain Res Cogn Brain Res. 1998;7(2):
221–33.
73. Short KR, Sheffield-Moore M, Costill DL. Glycemic and insu-
linemic responses to multiple preexercise carbohydrate feedings.
Int J Sport Nutr. 1997;7(2):128–37.
74. Galbo H, Christensen NJ, Holst JJ. Catecholamines and pancre-
atic hormones during autonomic blockade in exercising man.
Acta Physiol Scand. 1977;101(4):428–37.
75. Rollo I, Williams C. Effect of mouth-rinsing carbohydrate solu-
tions on endurance performance. Sports Med. 2011;41(6):
449–61.
76. Beaven CM, Maulder P, Pooley A, et al. Effects of caffeine and
carbohydrate mouth rinses on repeated sprint performance. Appl
Physiol Nutr Metab. 2013;38(6):633–7. doi:10.1139/apnm-2012-
0333.
77. Chambers ES, Bridge MW, Jones DA. Carbohydrate sensing in
the human mouth: effects on exercise performance and brain
activity. J Physiol. 2009;587(Pt 8):1779–94.
78. Gant N, Stinear CM, Byblow WD. Carbohydrate in the mouth
immediately facilitates motor output. Brain Res. 2010;1350:
151–8.
79. Foskett A, Ali A, Gant N. Caffeine enhances cognitive function
and skill performance during simulated soccer activity. Int J Sport
Nutr Exerc Metab. 2009;19(4):410–23.
80. Stuart GR, Hopkins WG, Cook C, et al. Multiple effects of caf-
feine on simulated high-intensity team-sport performance. Med
Sci Sports Exerc. 2005;37(11):1998–2005.
81. Ryan EJ, Kim CH, Fickes EJ, et al. Caffeine gum and cycling
performance: a timing study. J Strength Cond Res.
2013;27(1):259–64. doi:10.1519/JSC.0b013e3182541d03.
82. Kalmar JM. The influence of caffeine on voluntary muscle acti-
vation. Med Sci Sports Exerc. 2005;37(12):2113–9.
83. Kamimori GH, Karyekar CS, Otterstetter R, et al. The rate of
absorption and relative bioavailability of caffeine administered in
chewing gum versus capsules to normal healthy volunteers. Int J
Pharm. 2002;234(1–2):159–67.
M. Russell et al.
123
... During the half-time period, acid-base balance and glycemic response changes may further affect performance in the initial stage of the second half. 1 The total distance covered and the distance covered at high speed were shown to be reduced in the first 15-min of the second half when compared with the corresponding period of the first half. 2 In addition to reporting diminished physical output, studies have observed impaired cognitive performance between the first and second halves. ...
... Specifically, the increase in response accuracy observed during the first 30-min of intermittent exercise was attenuated in the first 15-min of the second half. 1,3 Therefore, half-time practices appear to influence subsequent performance during the initial stages of the second half. 1 Adopting appropriate recovery strategies at half-time to help players service their cognitive needs and restore their physical strength could help maintain or even improve performance in the initial stage of the second half. ...
... 1,3 Therefore, half-time practices appear to influence subsequent performance during the initial stages of the second half. 1 Adopting appropriate recovery strategies at half-time to help players service their cognitive needs and restore their physical strength could help maintain or even improve performance in the initial stage of the second half. ...
Article
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Background Mindfulness-based intervention (MBI) as a psychological treatment is adopted in the sports field, but its effect during competition has not been explored. This study investigated the acute effect of a brief MBI on athletes’ cognitive function after a 45-min, lab-based soccer protocol. Methods In a single-blind randomized counter-balanced crossover design, 17 male soccer players completed two main trials—an MBI trial and a control trial. The MBI trial was provided with a brief MBI after 45-min exercise; the control trial was instead assigned a travel-related audio to listen to at that time. In each main trial, cognitive function (i.e., Stroop task for inhibition; Corsi-block tapping task for working memory), salivary cortisol, blood lactate and mental fatigue were measured at baseline (pretest) and after the intervention (posttest). The cerebral oxygenation status was recorded using functional near-infrared spectroscopy during the cognitive function test. Results The brief MBI improved working memory performance in terms of both reaction time (pre vs. post, P = 0.02, d = 0.71) and accuracy (pre vs. post, P = 0.009, d = 0.58), supported by eliciting increased oxyhemoglobin concentration in the prefrontal cortex of the brain. Whereas a slightly better cognitive performance for MBI trial than control trial at posttest (P = 0.37, d = 0.32) accompanied by a lower oxyhemoglobin concentration. A lower mental fatigue level (P = 0.05, d = 0.6) and lower cortisol concentration (P = 0.04, d = 0.65) were observed in the MBI trial than in the control trial after the intervention at posttest. The decreased cortisol concentration correlated with increased inhibition performance in the MBI trial. Conclusion The acute effect of MBI on athletes’ mental fatigue and cortisol concentration was detected, and the beneficial effect on working memory was preliminarily supported. In general, MBI is recommended to be adopted at half-time of a soccer game.
... Consequently, athletes and coaches continue to design their routines based solely on their experience [7]. This is a matter of concern since the passive nature of the competition breaks leads to a decline in physical and cognitive performance and increases the risk of injury [8]. Thus, coaches and sports scientists need to have valuable information at hand regarding how to develop RW-U to optimize athletes' performance and reduce injury risk. ...
... For instance, Hammami et al. [5] specifically reviewed investigations focused on soccer, while Silva et al. [7] examined the efficacy of RW-U activities in explosive sports and exclusively included studies involving experienced athletes, regardless of their design. The latter is a point to consider producing the highest level of scientific evidence, as systematic reviews should be based on the inclusion and detailed analysis of the randomized controlled trials (RCTs) published on the subject so far [8]. Finally, Russell et al. [9] carried out a broad review of the effects of different strategies to improve sports performance after breaks. ...
... The study's samples ranged from 7 to 22 participants (age range: 16-33 years), with a competitive level varying from amateur to elite. Participants were soccer players in seven studies [11,12,16,[21][22][23][24], two studies involved rugby players [8,13], two investigations proposed an intermittent sport-like activity [17,19], and three trials included active people [14,15,20]. ...
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Background and Objectives: The passive nature of rest breaks in sport could reduce athletes’ performance and even increase their risk of injury. Re-warm-up activities could help avoid these problems, but there is a lack of research on their efficacy. This systematic review aimed at analyzing the results of those randomized controlled trials (RCTs) that provided information on the effects of re-warm-up strategies. Materials and Methods: Four electronic databases (Web of Science, Scopus, PubMed, and SPORTDiscus) were searched from their inception to January 2021, for RCTs on the effects of re-warm-up activities on sports performance. Interventions had to be implemented just after an exercise period or sports competition. Studies that proposed activities that were difficult to replicate in the sport context or performed in a hot environment were excluded. Data were synthesized following PRISMA guidelines, while the risk of bias was assessed following the recommendations of the Cochrane Collaboration. Results: A total of 14 studies (178 participants) reporting data on acute or short-term effects were analyzed. The main outcomes were grouped into four broad areas: physiological measures, conditional abilities, perceptual skills, and sport efficiency measures. The results obtained indicated that passive rest decreases physiological function in athletes, while re-warm-up activities could help to improve athletes’ conditional abilities and sporting efficiency, despite showing higher fatigue levels in comparison with passive rest. The re-warm-up exercise showed to be more effective than passive rest to improve match activities and passing ability. Conclusions: Performing re-warm-up activities is a valuable strategy to avoid reducing sports performance during prolonged breaks. However, given that the methodological quality of the studies was not high, these relationships need to be further explored in official or simulated competitions.
... timing) of these factors could have been ignored. In this respect, and on the basis of the aforementioned and other recent reviews on this topic [12,[19][20][21], we suggest the consideration of other potential moderators of PAPE factors ( Figure 2). ...
... Meanwhile, the timing for implementation of the CAs (i.e. how the conditioning stimuli are distributed over time) is another moderator that has received less attention and that may include both intra-session effort distribution as set configuration [17,29] and delayed potentiation effects as is commonly observed in in team sports with re-warm-up [20,30] and priming strategies [21,31]. Interestingly, although there is a body of evidence suggesting an enhancement of power performances for up to 48 hours after a CA [21], it is not clear if this delayed potentia- tion has some physiological association with classic PAP and PAPE mechanisms. ...
... re-warm-up refers to strategies designed to maintain or recover the elevated body temperature and neuromuscular capacity of a previous warm-up. While body temperature could be passively maintained with heated garments [59], the use of PAPE strategies would seem appropriate to increase muscle performances [20,59]. This is especially important during halves of competitive matches in team sports [20]. ...
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In this review, we will present and critically discuss how different conditioning exercises can be implemented in training, testing, and competition for the enhancement of performances in different sports, via post-activation performance enhancement and other delayed potentiation responses. The potentiation approaches described here include warming up, testing and monitoring, re-warm-up and priming strategies, and complex training. The post-activation performance enhancement responses can be best described following the new taxonomy, which allows the identification of the best strategies in every specific sport setting. This requires identifying the post-activation performance enhancement factors, which are the conditioning activity, the verification test, the population of athletes; and potential moderators (i.e. exercise type and loading, timing; recovery interval, target exercise, performance parameter; training background, age, and sex). The inherent limitations to these approaches, including the gaps in literature requiring further studies, may be overcome in practice by using individualized approaches.
... However, there seems to be a proportional association between the specificity and the intensity of the CA and PAPE which has been similarly defined in many warm-up practices (2,13,14). This concept suggests that athletes could optimize prior to performing a maximal activity by using a CA similar in nature and intensity to the expected outcome (15). ...
... Coaches would closely emulate the tasks and skills required in competition within the warm-up phase to affect this specificity principle. There is a positive performance correlation between a sport and its warm-up processes (14). Similarly, a common theme relating to the effectiveness of PAPE, is how closely the CA relates to the outcome task (25). ...
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Postactivation performance enhancement (PAPE) is a principle that an acute bout of high intensity voluntary exercise is followed by an enhancement in strength, speed or power production. As an integral part of the warm-up, this study intended to show a direct correlation between intensity, specificity and the outcome of a maximal task of sprint accelerations compared to a previously defined weighted plyometric intervention. In a randomised controlled, double-blind trial, adult professional footballers undertook 20m maximal sprint accelerations at a baseline and at 2 and 6 minutes post-intervention after 1 of 3 interventions; 2 repetitions of 20m sprint accelerations (S), 3x10 alternative leg weighted bounding (P) and control (C). All the baseline outcomes were similar between the groups. Relative to the baseline there was a significant improvement for S over 10m and 20m at 2 minutes of 0.12m.s⁻¹ and 0.11m.s⁻¹ and at 6 minutes of 0.11m.s⁻¹ and 0.12m.s⁻¹. Relative to the baseline P also had a significant improvement over 10m and 20m at 2 minutes 0.09m.s⁻¹ and 0.09m.s⁻¹ and at 6 minutes of 0.11m.s⁻¹ and 0.09m.s⁻¹ There was also a significant improvement in C between 2 and 6 minutes post-intervention at 10m and 20m of 0.06m.s⁻¹ and 0.08m.s⁻¹. There was no significant difference between the interventions and C. This finding suggests that a maximal sprint acceleration may enhance the outcome of a subsequent maximal sprint acceleration at 2 minutes, but the latter results could not be directly attributed to the interventions as previous testing is likely to have influenced these outcomes.
... In soccer, re-warm-up (RWU) may increase players' readiness to perform actions at different intensity levels [1] at the start of the second half of a match, thereby enhancing their athletic performance [2]. Indeed, RWU strategies have demonstrated that soccer players' acute explosive performance improved during the first minutes of the second half of the match [3][4][5]. ...
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ABSTRACT: This systematic review aimed to (1) identify and summarize studies that have examined the effects of re-warm-up (RWU) protocols on the physical performance of soccer players (vertical height jump and sprinting time) and (2) establish a meta-comparison between performing a re-warm-up and not performing one regarding the outcomes of the aforementioned outcomes. A systematic review of EBSCO, PubMed, Scielo, SPORTDiscus, and Web of Science databases was performed on January 12th, 2021, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. From the 892 studies initially identified, four studies were reviewed, and three of these were included in the present meta-analysis. Compared to a control condition, there was a moderate effect of RWU on vertical height jump (ES = 0.66; p = 0.001; I2 = 0.0%). However, compared to a control condition, there was a trivial effect of RWU on linear sprint time (ES = 0.19; p = 0.440; I2 = 38.4%). The nature of RWU enhances the performance of players with an emphasis on actions requiring vertical jumps. Therefore, the results provide essential and crucial information that soccer coaching staff can use to improve the performance of their teams. The reduced number of studies available for meta-analysis may have magnified the impact of heterogeneity on linear sprint time findings. More high-quality studies, with homogeneous study designs, may help to clarify the potential benefits of RWU on linear sprint time.
... The present results suggest that strength and conditioning coaches should give particular attention to design and implement warm-up routines that lead to moderate (1-3°C) increases in muscle temperature and, more importantly, to customize the warm-up to the needs and demands of the environmental conditions. Recent review papers provide detailed recommendations on the development of effective warm-up protocols (Racinais & Oksa, 2010;Russell et al., 2015;Silva et al., 2018;West et al., 2016). During the halftime break in basketball and other team sports, athletes who were already in the game should remain active to prevent reductions in muscle temperature, while substitutions must use re-warm-up strategies to reestablish a higher muscle temperature and be ready to enter the game. ...
Article
Purpose: We performed two studies to investigate: the minute-by-minute changes in muscle temperature following a 20-min warm-up routine (Study-1) and the impact of the typical post-warm-up period of inactivity on the performance of basketball athletes (Study-2). Method: In Study-1, 26 males (age: 23.6 ± 6.2 yr; BMI: 24.1 ± 3.1 kg/m2) performed a 20-min cycling warm-up and then rested for 20 min. Tibialis anterior muscle temperature was assessed throughout. In Study-2, six male professional basketball players (age: 24.9 ± 4.6 yr; BMI: 25.5 ± 1.8 kg/m2) performed a series of basketball performance tests after a 20-min warm-up, as well as 9-min and 23-min into a post-warm-up period of inactivity. Results: On average, muscle temperature increased by 0.1°C every minute during warm-up and dropped by the same amount every minute during inactivity. The increase during warm-up and the decrease during inactivity were higher at the start of each period. A 9-min inactivity period is accompanied by 3.8 ± 0.6% reduction in countermovement jump (p = .046). A 23-min inactivity period is accompanied by 7.3 ± 0.7% reduction in lay-up points (p = .027). Conclusion: These two studies show that a 20-min warm-up routine increases muscle temperature but this benefit is lost after a typical post-warm-up inactivity period in high-level basketball, leading to reductions in certain aspects of athletic performance.
... What we actually do know is that these meetings are usually conducted in a way that the coach delivers the speech while the players are passive listeners. 12 It is therefore clear that more information on the content and efficacy of these meetings is needed. ...
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This study was designed to explore coaches' half-time speeches and whether players perceive these speeches as having an impact on their performance later in the game. A mixed-methods convergent design was used. Participants were nine male basketball players aged 19-34 (M = 27, SD = 4.76) from a team playing in the Israeli Basketball Premier League, as well as their head coach (aged 41) and two assistant coaches (aged 51 and 34). Data were collected on the coach's speeches at half-time in games during the regular season. In addition, face-to-face semi-structured interviews with the players and the two assistant coaches were conducted at midseason. The average speech duration was approximately 3 min, and messages were delivered at an average pace of one theme every 13 s. The most frequent theme was psychological , with more negative themes delivered compared to positive ones. Psychological themes appeared 50% more than informational. We discuss the differences in the features of the talks between games in which the team was trailing at half-time, and games in which they reached half-time with a leading score. A surprising gap exists between the participants' perception regarding the contribution of the half-time speech to players' performance, and the actual score at the end of the game.
... Another crucial point was the large number of goals right after the half-time break. In this context, we recommend re-warm-up as a way to prepare athletes for the second half [30,31], mitigating the consequences of inactivity during the half-time. ...
... The guidelines for PAPE using HRT exist within narrow parameters with a high proportion of non-responders prompting cautionary recommendations from investigators to individualise the delay times after the conditioning activity (CA) to achieve the desired effect (Wilson et al., 2013). However, there seems to be a proportional association between the specificity and the intensity of the CA and PAPE which has been similarly defined in many warm-up practices (van den Tillaar et al., 2019;Burkett, Phillips, & Ziuraitis, 2005;Russell, West, Harper, Cook, & Kilduff, 2015). This concept suggests that athletes could optimise prior to performing a maximal activity by using a CA similar in nature and intensity to the expected outcome (Suchomel, Comfort, & Lake, 2017). ...
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Background: Postactivation performance enhancement (PAPE) is a principle that suggests that an acute bout of high intensity voluntary exercise will be followed by an improvement in strength, power, and speed of a subsequent task. This study intended to demonstrate how a maximal vertical jump can enhance the outcome of a subsequent vertical jump compared to a multiple jump series and a control. Methods: In a randomised controlled, double blind trial, adult professional soccer players (n = 69) undertook maximal vertical jumps at baseline and at 2 and 6 minutes post-intervention after 1 of 3 interventions; 2 repetitions of a maximal vertical jump (VJ), 40 repetitions of a multiple jump series (MJ) or a walking control (CON). Results: All baseline outcomes were similar between all the groups. Relative to the baseline there was a significant improvement for VJ in jump height and power output at 2 minutes of 1.89cm and 114.45W and relative to the baseline, MJ also had a significant improvement at 2 minutes of 1.51cm and 91.60W. By 6 minutes both groups had reverted to baseline values. There was no change in CON across the experiment and no significant difference between CON and the interventions. Conclusions: These findings suggests that 2 maximal vertical jumps may enhance the outcome of a subsequent maximal vertical jump after 2 minutes and as much as a series of 40 jumps. However, these enhancements were not sustained for a further 4 minutes in either group.
Article
We present data displaying course-based undergraduate research experiences (CUREs) effectiveness in providing authentic cutting-edge research experiences to undergraduates, which both private and government organizations recognize as essential. A total of 68 students were enrolled in this research with 50 students being in a traditional laboratory course and 18 students participating in the CURE implemented laboratory. Results from mid- and postsemester surveys were compared to assess knowledge and attitude. Knowledge showed no change; however, students who experienced the CURE responded with increased enjoyment, strong feelings of scientific contribution, and high project ownership, and overall they were more confident in research than their non-CURE peers.
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Despite limited scientific evidence supporting their effectiveness, warm-up routines prior to exercise are a well-accepted practice. The majority of the effects of warm up have been attributed to temperature-related mechanisms (e.g. decreased stiffness, increased nerve-conduction rate, altered force-velocity relationship, increased anaerobic energy provision and increased thermoregulatory strain), although non-temperature-related mechanisms have also been proposed (e.g. effects of acidaemia, elevation of baseline oxygen consumption (V̇O2) and increased postactivation potentiation). It has also been hypothesised that warm up may have a number of psychological effects (e.g. increased preparedness). Warm-up techniques can be broadly classified into two major categories: passive warm up or active warm up. Passive warm up involves raising muscle or core temperature by some external means, while active warm up utilises exercise. Passive heating allows one to obtain the increase in muscle or core temperature achieved by active warm up without depleting energy substrates. Passive warm up, although not practical for most athletes, also allows one to test the hypothesis that many of the performance changes associated with active warm up can be largely attributed to temperature-related mechanisms.
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While warm up is considered to be essential for optimum performance, there is little scientific evidence supporting its effectiveness in many situations. As a result, warm-up procedures are usually based on the trial and error experience of the athlete or coach, rather than on scientific study. Summarising the findings of the many warm-up studies conducted over the years is difficult. Many of the earlier studies were poorly controlled, contained few study participants and often omitted statistical analyses. Furthermore, over the years, warm up protocols consisting of different types (e.g. active, passive, specific) and structures (e.g. varied intensity, duration and recovery) have been used. Finally, while many studies have investigated the physiological responses to warm up, relatively few studies have reported changes in performance following warm up. The first part of this review critically analyses reported changes in performance following various active warm-up protocols. While there is a scarcity of well-controlled studies with large subject numbers and appropriate statistical analyses, a number of conclusions can be drawn regarding the effects of active warm up on performance. Active warm up tends to result in slightly larger improvements in short-term performance (10 seconds, but 2). While active warm up has been reported to improve endurance performance, it may have a detrimental effect on endurance performance if it causes a significant increase in thermoregulatory strain. The addition of a brief, task-specific burst of activity has been reported to provide further ergogenic benefits for some tasks. By manipulating intensity, duration and recovery, many different warm-up protocols may be able to achieve similar physiological and performance changes. Finally, passive warm-up techniques may be important to supplement or maintain temperature increases produced by an active warm up, especially if there is an unavoidable delay between the warm up and the task and/or the weather is cold. Further research is required to investigate the role of warm up in different environmental conditions, especially for endurance events where a critical core temperature may limit performance.
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Reduced physical performance has been observed following the half-time period in team sports players, likely due to a decrease in muscle temperature during this period. We examined the effects of a passive heat maintenance strategy employed between successive exercise bouts on core temperature (Tcore) and subsequent exercise performance. Eighteen professional Rugby Union players completed this randomised and counter-balanced study. After a standardised warm-up (WU) and 15 min of rest, players completed a repeated sprint test (RSSA 1) and countermovement jumps (CMJ). Thereafter, in normal training attire (Control) or a survival jacket (Passive), players rested for a further 15 min (simulating a typical half-time) before performing a second RSSA (RSSA 2) and CMJ's. Measurements of Tcore were taken at baseline, post-WU, pre-RSSA 1, post-RSSA 1 and pre-RSSA 2. Peak power output (PPO) and repeated sprint ability was assessed before and after the simulated half-time. Similar Tcore responses were observed between conditions at baseline (Control: 37.06±0.05°C; Passive: 37.03±0.05°C) and for all other Tcore measurements taken before half-time. After the simulated half-time, the decline in Tcore was lower (-0.74±0.08% vs. -1.54±0.06%, p<0.001) and PPO was higher (5610±105 W vs. 5440±105 W, p<0.001) in the Passive versus Control condition. The decline in PPO over half-time was related to the decline in Tcore (r = 0.632, p = 0.005). In RSSA 2, best, mean and total sprint times were 1.39±0.17% (p<0.001), 0.55±0.06% (p<0.001) and 0.55±0.06% (p<0.001) faster for Passive versus Control. Passive heat maintenance reduced declines in Tcore that were observed during a simulated half-time period and improved subsequent PPO and repeated sprint ability in professional Rugby Union players.
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As the acceleration and deceleration demands of soccer are currently not well understood, this study aimed to profile markers of acceleration and deceleration capacity during professional soccer match-play. This within-player observational study required reserve team players from a Premier League club to wear 10 Hz Global Positioning System units throughout competitive matches played in the 2013/2014 competitive season. Data is presented for players who completed four or more games during the season (n = 11) and variables are presented according to six 15 min intervals (I1-6: 00:00-14:59 min, 15:00-29:59 min, 30:00-44:59 min, 45:00-59:59 min, 60:00-74:59 min, 75:00-89:59 min). During I6, the distance covered (total, per minute, and at high intensity), number of sprints, accelerations (total and high intensity), decelerations (total and high intensity), and impacts were reduced compared to I1 (all P ≤ 0.05). The number of high intensity impacts remained unchanged throughout match-play (P > 0.05). These findings indicate that high intensity actions and markers of acceleration and deceleration capacity are reduced in the last 15 min of the normal duration of match-play. Such information can be used to increase the specificity of training programmes designed for soccer players while also giving further insight in to the effects of 90 min of soccer-specific exercise. Interventions that seek to maintain the acceleration and deceleration capacity of players throughout the full duration of a soccer match warrant investigation.
Article
Hypoglycaemia unawareness, is a major risk factor for severe hypoglycaemia and a contraindication to the therapeutic goal of near-normoglycaemia in IDDM. We tested two hypotheses, first, that hypoglycaemia unawareness is reversible as long as hypoglycaemia is meticulously prevented by careful intensive insulin therapy in patients with short and long IDDM duration, and that such a result can be maintained long-term. Second, that intensive insulin therapy which strictly prevents hypoglycaemia, can maintain long-term near-normoglycaemia. We studied 21 IDDM patients with hypoglycaemia unawareness and frequent mild/severe hypoglycaemia episodes while on “conventional” insulin therapy, and 20 nondiabetic control subjects. Neuroendocrine and symptom responses, and deterioration in cognitive function were assessed in a stepped hypoglycaemia clamp before, and again after 2 weeks, 3 months and 1 year of either intensive insulin therapy which meticulously prevented hypoglycaemia (based on physiologic insulin replacement and continuous education, experimental group, EXP, n=16), or maintenance of the original “conventional” therapy (control group, CON, n=5). At entry to the study, all 21 IDDM-patients had subnormal neuroendocrine and symptom responses, and less deterioration of cognitive function during hypoglycaemia. After intensive insulin therapy in EXP, the frequency of hypoglycaemia decreased from 0.5±0.05 to 0.045±0.02 episodes/patient-day; HbA1C increased from 5.83±0.18 to 6.94±0.13% (range in non-diabetic subjects 3.8–5.5%) over a 1-year period; all counterregulatory hormone and symptom responses to hypoglycaemia improved between 2 weeks and 3 months, with the exception of glucagon which improved at 1 year; and cognitive function deteriorated further as early as 2 weeks (p<0.05). The improvement in responses was maintained at 1 year. The improvement in plasma adrenaline and symptom responses inversely correlated with IDDM duration. In contrast, in CON, neither frequency of hypoglycaemia, nor neuroendocrine responses to hypoglycaemia improved. Thus, meticulous prevention of hypoglycaemia by intensive insulin therapy reverses hypoglycaemia unawareness even in patients with long-term IDDM, and is compatible with long-term near-normoglycaemia. Because carefully conducted intensive insulin therapy reduces, not increases the frequency of moderate/severe hypoglycaemia, intensive insulin therapy should be extended to the majority of IDDM patients in whom it is desirable to prevent/delay the onset/progression of microvascular complications.
Article
To assess the relative roles of insulin and hypoglycaemia on induction of neuroendocrine responses, symptoms and deterioration of cognitive function (12 cognitive tests) during progressive decreases in plasma glucose, and to quantitate glycaemic thresholds, 22 normal, non-diabetic subjects (11 males, 11 females) were studied on four occasions: prolonged fast (n=8, saline euglycaemia study, SA-EU), stepped hypoglycaemia (plasma glucose plateaus of 4.3, 3.7, 3 and 2.3 mmol/l) or euglycaemia during insulin infusion at 1 and 2 mU·kg−1·min−1 (n=22, high-insulin hypoglycaemia and euglycaemia studies, HI-INS-HYPO and HI-INS-EU, respectively), and stepped hypoglycaemia during infusion of insulin at 0.35 mU· kg−1·min−1 (n=9, low-insulin hypoglycaemia study, LO-INS-HYPO). Insulin per se (SA-EU vs HI-INS-EU), suppressed plasma glucagon (∼20%) and pancreatic polypeptide (∼30%), whereas it increased plasma noradrenaline (∼R10%, p<0.05). Hypoglycaemia per se (HI-INS-HYPO vs HI-INS-EU) induced responses of counterregulatory hormones (CR-HORM), symptoms and deteriorated cognitive function. With the exception of suppression of endogenous insulin secretion, which had the lowest glycaemic threshold of 4.44±0.06 mmol/l, pancreatic polypeptide, glucagon, growth hormone, adrenaline and cortisol had similar glycaemic thresholds (∼3.8-3.6 mmol/l); noradrenaline (3.1±0.0 mmol/l), autonomic (3.05±0.06 mmol/l) and neuroglycopenic (3.05±0.05 mmol/l) symptoms had higher thresholds. All 12 tests of cognitive function deteriorated at a glycaemic threshold of 2.45±0.06 mmol/l, but 7 out of 12 tests were already abnormal at a glycaemic threshold of 2.89±0.06 mmol/l. Although all CR-HORM had a similar glycaemic threshold, the lag time of response (the time required for a given parameter to increase) of glucagon (15±1 min) and growth hormone (14±3 min) was shorter than adrenaline (19±3 min) and cortisol (39±4 min) (p<0.05). With the exception of glucagon (which was suppressed) and noradrenaline (which was stimulated), insulin per se (HI-INS-HYPO vs LO-INS-HYPO) did not affect the responses of CR-HORM, and did not influence the symptoms or the cognitve function during hypoglycaemia. Despite lower responses of glucagon, adrenaline and growth hormone (but not thresholds) in females than males, females were less insulin sensitive than males during stepped hypoglycaemia.
Article
Formulation of oral rehydration solutions (ORS) is reviewed in the context of methods for measuring absorption of water and component substrates, transport mechanisms of substrates and water, requirements of the athlete, and effects of exercise on absorption. The triple lumen tube intubation perfusion method is the optimal technique for obtaining absorption data from the human small intestine during rest and exercise. Factors that must be considered when interpreting absorption data obtained by this technique include the role of the mixing segment in altering composition of the infused solution, defining optimal segment length, effects of ORS osmolality, and absorption of ''nonabsorbed'' indicators. Absorption data are applicable only to the test segment and may lack relevance to ORS transport proximal and distal to the test segment. Absorption rate of an ORS measured by perfusion may not correlate with absorption rate following ingestion. Transport of water, electrolytes, carbohydrates, and other solutes including glutamine and amino acids is considered in relation to ORS formulation. Factors affecting absorption of an ORS including the unstirred layer, motility, intestinal blood flow, and maximal absorptive capacity pf the alimentary tract are considered. Exercise per se at 30-70% VO2max far 60-90 min probably has minimal effects in limiting absorption of an ORS. Consideration relevant to supplying needs of the athlete during prolonged exercise in relation for ORS formulation are discussed.