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Journal of Applied Sport Psychology
ISSN: 1041-3200 (Print) 1533-1571 (Online) Journal homepage: http://www.tandfonline.com/loi/uasp20
Beat the Heat: Effects of a Motivational Self-Talk
Intervention on Endurance Performance
Antonis Hatzigeorgiadis, Khelifa Bartura, Christos Argiropoulos, Nikos
Comoutos, Evangelos Galanis & Andreas Flouris
To cite this article: Antonis Hatzigeorgiadis, Khelifa Bartura, Christos Argiropoulos, Nikos
Comoutos, Evangelos Galanis & Andreas Flouris (2017): Beat the Heat: Effects of a Motivational
Self-Talk Intervention on Endurance Performance, Journal of Applied Sport Psychology, DOI:
10.1080/10413200.2017.1395930
To link to this article: http://dx.doi.org/10.1080/10413200.2017.1395930
Accepted author version posted online: 24
Oct 2017.
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Beat the Heat: Effects of a Motivational Self-Talk Intervention on Endurance Performance
Antonis Hatzigeorgiadis, Khelifa Bartura, Christos Argiropoulos, Nikos Comoutos, Evangelos
Galanis, & Andreas Flouris
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Department of Physical Education & Sport Science, University of Thessaly
Running head: self-talk in the heat
Address for Correspondence
Antonis Hatzigeorgiadis
Department of Physical Education & Sport Science
University of Thessaly
Trikala, 42100
Greece
Tel: +30 24310 47009
ahatzi@pe.uth.gr
E-mail addresses of co-authors
Khelifa Bartura: kbartura@gmail.com
Christos Argiropoulos: xr.argiropoulos@hotmail.com
Nikos Comoutos: nzourba@pe.uth.gr
Evangelos Galanis: v.galanis@hotmail.com
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Andreas Flouris: andreasflouris@gmail.com
Abstract
The study examined the effects of a motivational self-talk intervention on endurance cycling
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performance in hot conditions. Participants were 16 physically active adult males. After a
baseline VO2 peak assessment and two training session participants completed a 30min cycling
trial in a hot environment (35ºC, 45% relative humidity), while maintaining a steady rate of
perceived exertion. Participants of the intervention group produced greater power output during
the final third of the trial. Findings suggest that the self-talk strategy seems to have compromised
the aversive effects of the demanding environmental conditions, and provide support for the
psychobiological model of endurance performance.
Key words: self-talk mechanisms, psychobiological model, stressful environment, RPE, cycling
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Beat the Heat: Effects of a Motivational Self-Talk Intervention on Endurance Performance
The links between thought and action have led sport psychologists to developing self-regulation
strategies and implement interventions aimed to enhance performance through the regulation of
cognitions. Self-talk interventions have attracted considerable research interest in recent years,
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and there is now robust evidence for the effectiveness of self-talk strategies through systematic
(Tod, Hardy, & Oliver, 2011) and meta-analytic reviews (Hatzigeorgiadis, Zourbanos, Galanis,
& Theodorakis, 2011). In particular, the meta-analysis has revealed an overall effect size (d) of
0.48, suggesting that self-talk can meaningfully facilitate learning and enhance performance in
sport tasks. In addition, a number of potential moderators that may regulate the size of the effect
were identified, showing that (a) self-talk interventions were more effective for fine compared to
gross tasks, and for novel compared to well learned tasks, (b) that instructional self-talk was
more effective for fine compared to gross tasks, and that instructional self-talk was more
effective for fine tasks compared to motivational self-talk; and (c) that intervention including
self-talk training were more effective than those not including training.
The differential effects of different self-talk types were already suggested through the
matching hypothesis introduced by Theodorakis, Weinberg, Natsis, Douma, and Kazakas (2000),
who argued that instructional self-talk should be more effective for fine tasks whereas
motivational self-talk for gross tasks. This postulation has received partial support in subsequent
studies (e.g. Hatzigeorgiadis, Theodorakis, & Zourbanos, 2004) and the meta-analysis (e.g.
Hatzigeorgiadis et al., 2011). Moreover, there is evidence that other factors should also be
considered when developing self-talk plans, such as skill level of participants (Hardy, Begley
and Blanchfield, 2015) and prior experience with the task (Zourbanos, Hatzigeorgiadis, Bardas,
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& Theodorakis, 2013). Considering that different self-talk types may yield different effects, the
idea that self-talk may operate through different mechanisms was forwarded. Hardy, Oliver, and
Tod (2009) introduced a conceptual model describing four clusters of mechanisms that could
help explain the effects of self-talk on performance: cognitive, motivational, affective, and
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behavioral mechanisms. The model provided direction and helped advancing research on selftalk mechanisms. Eventually, Galanis, Hatzigeorgiadis, Zourbanos, and Theodorakis (2016)
reviewed the relevant research and provided insights onto the attentional and motivational
mechanisms. Mostly relevant to the interests of this study, they described cognitive, affective and
behavioural aspects of motivation that may explain the effectiveness of self-talk strategies for
performance. Within this framework, Galanis et al. (2016) identified the psychobiological model
of endurance performance (Marcora, Bosio, & de Morree, 2008; Marcora, Staiano, & Manning,
2009) as particularly pertinent for the interpretation of the facilitating effects of self-talk for
endurance performance.
The psychobiological model of endurance performance considers endurance performance
from a motivational perspective, and posits that exhaustion, which limits the ability to sustain
aerobic exercise intensity and leads to the regulation of pace and task termination, is created by
conscious decision. The model identifies five psychological factors determining the conscious
regulation of pace and performance termination: one motivational factor, namely potential
motivation, and four cognitive factors, perception of effort, knowledge of the distance/time to
cover and distance/time remaining, and previous experiences of perception of effort during tasks
of varying intensity and duration. Among those factors perception of effort, described as the
conscious sensation of how hard, heavy and strenuous exercise is (Marcora, 2010), has been
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considered the most influential one. In constant intensity endurance tasks (e.g., Marcora et al.,
2009), or tasks where the regulation of pace is decided externally (e.g., Marcora et al., 2008), it is
predicted that increases in perceptions of effort beyond the individual‟s tolerance level will cause
termination of effort. In self-paced endurance tasks (e.g., Pageaux, Lepers, Dietz, & Marcora,
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2014), it is predicted that reduced perceptions of effort will lead to pace increase, whereas
increased perceptions of effort will lead to pace reduction, until the exertion of further effort is
deemed unwanted or unlikely to lead to goal attainment due to the difficulty of the task, thus
causing the termination of effort (Wright, 2008). Hence, any physiological or psychological
factor affecting perception of effort may influence endurance performance.
Self-talk strategies, and in particular motivational self-talk, has been shown to have
important motivational effects. Two studies with young tennis players have shown that using
motivational self-talk helped increasing self-efficacy (Hatzigeorgiadis, Zourbanos, Goltsios, &
Theodorakis, 2008) and self-confidence (Hatzigeorgiadis, Zourbanos, Mpoumpaki, &
Theodorakis, 2009), and reducing cognitive anxiety (Hatzigeorgiadis et al., 2009). Moreover, it
has been found that in an experimental swimming task participants using motivational self-talk
reported increased effort compared to participants using technical instruction self-talk
(Hatzigeorgiadis, 2006). Considering its motivational foundations the psychobiological model of
endurance performance provides a useful framework for the interpretation of the facilitating
effects of self-talk strategies, and in particular motivational self-talk, on endurance performance.
Two recent studies have explored the effectiveness of motivational self-talk in endurance
performance in combination with ratings of perceived exertion (RPE) and psychophysiological
variables through different outcome measures. Blanchfield, Hardy, de Morree, Staino, and
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Marcora (2014) used a time to exhaustion design to examine the effectiveness of a motivational
self-talk intervention on a cycling endurance task. Their results showed that the self-talk group
had greater cycling time to exhaustion and reported lower RPE during the task. In addition, they
found (a) no difference in facial electromyography (EMG) which was assessed as a
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psychophysiological measure of perceived effort during and near to the completion of the time to
exhaustion test, (b) no differences in heart rate during and at completion of the test, and (c) no
differences on blood lactate concentration 3min post-completion. In a similar study, but using a
time trial design, Barwood, Corbett, Wagstaff, McVeigh, and Thelwell (2015) examined the
effect of motivational self-talk on 10km cycling performance. They found that the motivational
self-talk group produced a higher power output, which was matched by higher oxygen
consumption, whereas no differences in RPE were reported. In both studies a perceptual
interpretation of the beneficial self-talk effects was forwarded. In the first because participants
cycled for more while reporting lower perception of exertion, whereas in the second because
participants produced greater power output while reporting similar perceptions of exertion; thus
both providing support to the psychobiological model of endurance performance and the fit of
self-talk interventions within this model.
An aspect of human performance that has received minimal attention in relation to the
use of self-talk strategies is performance under environmentally stressful conditions, such as
heat, which cause performance decrements. Galloway and Maughan (1997) argued that
performance impairments become progressively greater as heat stress increases, and perceptions
of fatigue play an important role in this process (Nielsen & Nybo, 2003). Gonzalez-Alonso et al.
(1999) argued that the early occurrence of fatigue during exercise in hot conditions can be
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attributed to the elevated core temperature. Moreover, Flouris and Schlader (2015) reported that
increases in skin and, to a lesser extent, core temperature may reduce drive and motivation to
perform in hot environments (in particular for prolonged exercise). However, they noted that
knowledge on this topic is currently based on anecdotal evidence and that further research is
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required to fully elucidate the links between thermoregulation, motivation, and performance.
Importantly, there is evidence supporting that elevated body temperature causes increased
perception of exertion during submaximal exercise in the heat (Armada-da-Silva, Woods, &
Jones 2004; Simmons, Mundel, & Jones, 2008). Thus, the psychobiological model or endurance
performance seems of great relevance in explaining performance differences in hot conditions. In
the sole study that examined the effects of self-talk in the heat, Wallace et al. (2016) examined
the effects of a motivational self-talk intervention on a cycling to exhaustion task. They found
that the self-talk group following the intervention managed to significantly prolong nearmaximal exercise before stopping while reporting similar perceptions of effort compared to
baseline. They attributed that effect to the continuous reappraisal of participants‟ desire to
voluntarily terminate exercise and perception of fatigue.
Considering the findings regarding the effectiveness of motivational self-talk in
endurance performance in relation to the accompanying RPE effects, and in addition the links
between exercise in hot condition and RPE, the use of self-talk strategies seems a useful tool for
attenuating the influence of fatigue and motivational losses when performing in the heat. The
present study aimed to examine the effectiveness of a motivational self-talk intervention on an
endurance cycling task under conditions of elevated heat. In particular, the study examined the
power output during 30min of cycling at a constant RPE in a hot environment (35ºC, 45%
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relative humidity). In addition, psychological (thermal sensation and thermal comfort) and
physiological (oxygen consumption, respiratory quotient, core temperature, skin temperature,
and muscle temperature) variables were assessed. These variables are the most widely used
indicators for assessing heat stress and the effect of internal and environmental factors (Flouris &
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Cheung, 2010a). Based on the evidence regarding the effectiveness of self-talk and the
psychobiological model of endurance performance we expected that under conditions of constant
RPE the self-talk group would produce higher output over the 30min of cycling.
Method
Participants
The study was conducted according to the principles expressed in the Declaration of
Helsinki and was approved by the Institution‟s Ethics Review Board (protocol no. 777). A total
of 16 healthy (no history of respiratory, metabolic, muscular, or cardiovascular pathologies) male
sport science students (age M = 22.5 years, SD = 4.9; height M = 1.81m, SD = 0.06, body mass
M = 78.44, SD = 9.19 kg; percent of body fat M = 11.23, SD = 3.51, peak oxygen uptake M =
51.19, SD = 7.84 ml·kg-1·min-1) volunteered following a call asking for fit males to participate
in an endurance cycling task in hot conditions, in return of a peak oxygen uptake (VO2peak)
assessment. Participants were informed of all experimental procedures, associated risks, and
discomforts, and provided written consent. The participants were randomly allocated into control
(n = 8) and self-talk (n = 8) groups. Independent samples t-tests showed no differences between
the two groups in height, t(14) = 1.09, p = .29, body mass, t(14) = 0.16, p = .87, percent body
fat, t(14) = 0.42, p = .68, VO2peak, t(14) = 0.51, p = .62.
Experimental Design
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During a preliminary session, participants received an orientation to the instrumentation
and the experimental protocols. Thereafter, a total of four visits to the laboratory were scheduled
for each participant within a period of five days. All visits took place between 11:00-14:00 h
(starting at the same time for each participant) and were scheduled as follows: a VO2peak test
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was conducted on day 1; training sessions were conducted on day 2 and day 3; no study activities
were planned on day 4; an experimental session was conducted on day 5.
On day 1, all participants underwent a VO2peak test on a cycloergometer (Monark
Ergomedic 874, Vansbro, Sweden) as described by Flouris, Metsios, Jamurtas, and Koutedakis
(2010). In brief, the test involved a 3-minute warm-up period of steady-state cycling at 60 W,
followed by increments of 30W·min-1 until exhaustion. Pedalling rate was maintained at 60 rpm
throughout. An automated gas analyser (Oxycon Mobile, CareFusion, San Diego, USA) was
used to record respiratory variables every 5 sec while individuals inspired room air. The
VO2peak (ml·kg-1·min-1) was defined as the highest oxygen uptake during the test, taken as the
mean of the two highest consecutive 5-sec recordings.
During days 2 and 3, all participants were trained on the cycloergometer. The training
involved a 2min warm-up period of steady-state cycling at 60W, followed by increments of 30W
every 2min. The exercise lasted a total of 12min and cadence was maintained at 60rpm
throughout. To familiarize participants with the RPE, they were asked to report it on a 15-point
Borg scale from 6 (no exertion at all) to 20 (maximal exertion) just before every increment in
cycloergometer resistance. Participants of the control group received no further
feedback/guidance prior to, during, or after each training session. Participants of the self-talk
group received a brief introduction on the use of self-talk strategies and subsequently trained
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using self-talk cues. Specifically, they were given the opportunity to choose their cues among a
list of relevant motivational cues typically used to boost motivation and effort such as, “let‟s go”,
“come on”, “keep going”, “stronger”, “hold on” (Zourbanos, Hatzigeorgiadis, Chroni,
Theodorakis, & Papaioannou, 2009), or to devise their own self-talk cues that would help them
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increase their motivation. The RPE measures that were taken every 2min were also used as a
trigger for self-talk; that is, participants were instructed to use their self-talk cues every time they
were asked to report their RPE. At the end of the training sessions, as a manipulation check,
participants of the self-talk group were asked to report how often they used their cues. On day 4,
there was no experimental activity and all participants were advised to refrain from intense
exercise (running, swimming, cycling, weight lifting, etc.) as well as other excessive stressors.
On day 5, all participants underwent the experimental session. They were instructed to
ingest at least 0.5L of water approximately 30min before their arrival at the lab. To ensure
appropriate hydration levels (Flouris & Cheung 2010a), upon arrival and before any testing had
begun, urine void (80mL) was collected in polyethylene specimen jars (Fisher Scientific,
Pittsburgh) for the determination of urine specific gravity using a refractometer (Atago, Tokyo,
Japan). Euhydration was defined as urine specific gravity <1.02 according to internationallyaccepted standards (American College of Sports Medicine; Sawka, Burke, Eichner, Maughan,
Montain, & Stachenfeld, 2007). All participants achieved euhydration, and no experimental
sessions required rescheduling. Thereafter, participants had their body mass measured using a
precision weighing scale (Ver. 5.3, KERN & Sohn GmbH, Balingen, Germany), they were given
cotton t-shirt and shorts to wear, and had the instruments for temperature and oxygen uptake
(VO2) applied on their body. Following instrumentation, participants entered an environmental
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chamber with ambient temperature and relative humidity set at 35°C (SD = 0.5) and 45% (SD =
2), respectively, following a previously recommended protocol (Hartley, Flouris, Plyley, &
Cheung, 2012). They were asked to exercise on the cycloergometer for 30min at a cadence of
60rpm while maintaining a RPE of 14 (corresponding to an intensity between „somewhat hard‟
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and „hard‟, Borg, 1970) by appropriately regulating pedalling resistance. The exercise intensity
of 14 RPE was specifically selected so that, when coupled with the stress of the environmental
conditions, caused sufficient strain to elicit voluntary changes in power output; however, not
stressful enough to cause volitional fatigue prior to the completion of the 30-minute protocol
(Hartley et al., 2012). No fluid consumption was allowed during the exercise protocol, while
participants were given no information or feedback regarding time and/or pedalling resistance
except a reminder to maintain an RPE of 14 every 5min. At that time, participants of the self-talk
group were also reminded to use their self-talk cues. At a 5min interval, thermal comfort and
thermal sensation were assessed. All participants successfully completed the 30min cycling
exercise in the heat. All assessments were conducted by two trained researchers, who were
simultaneously present at all occasions, and measurements of the targeted variables were
conducted using identical pre-calibrated equipment. The ambient conditions in the laboratory
(i.e., outside the environmental chamber) were set to normal indoor conditions for temperature
(23-24°C) and relative humidity (50-60%) during all sessions. Throughout the 5-day study
period, participants were asked to refrain from intense exercise, other excessive stressors,
alcohol, and the use of over-the-counter medications. They were also asked to refrain from
consuming caffeine for 12 hours before the experimental session.
Measurements
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Power output
Power output during the experimental session for the entire 30min exercise protocol was
calculated using the following equation and the data was fragmented into six interval taking
averages at every 5min for the data analysis:
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Power Output (W) = pedal revolutions/min · 6 meters/revolution · resistance (kp)
Oxygen consumption
Oxygen consumption (VO2 in ml·kg-1·min-1) and the respiratory quotient (i.e., the ratio of
carbon dioxide production to oxygen consumption) were recorded throughout the exercise
protocol using an automated gas analyser (Oxycon Mobile, CareFusion, San Diego, USA) every
5sec while participants inspired room air through a facemask.
Temperature
Core, skin, and muscle temperatures were recorded throughout exercise in the
experimental session at 8sec intervals using the Temperature Monitor 100 (Biomnic Ltd.,
Trikala, Greece) interfaced with a computer so that temperatures could be monitored
continuously. Core temperature was evaluated via exhaled air using previously-described
procedures (Flouris & Cheung 2010b) and the Exhaled Temperature Module of the Temperature
Monitor 100. The system is inserted within the exhaled air canals of the gas analyzer used to
assess VO2 and uses a thermistor (400 series, Mon-A-Therm, Mallinkrodt Medical, USA) to
record exhaled temperature.
Skin temperature was measured at 4 sites using thermistors (400 series, Mon-A-Therm,
Mallinkrodt Medical, USA) attached to the skin with surgical tape. Mean skin temperature (Tsk)
was subsequently calculated using a weighted average of four sites in accordance with
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Ramanathan (1964). Temperature of the tibialis anterior muscle was measured using the
insulation disk technique as previously described (Flouris, Dinas, Tsitoglou, Patramani,
Koutedakis, & Kenny, 2015). For the analysis the temperature data were fragmented into six
interval taking averages at every 5min.
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Use of self-talk
The use of self-talk during the training and the experimental sessions was assessed using
two protocols (Hatzigeorgiadis et al., 2009). The first involved the use of self-talk during training
for the participants of the self-talk group. Participants were asked to indicate how frequently they
were using their self-talk cues on a 10-point scale, from 1 (not at all) to 10 (all the time). The
second protocol involved the use of self-talk for the experimental testing. Participants in the selftalk group were asked to indicate (a) how frequently they were using their chosen self-talk cues,
(b) whether they were using some other type of self-talk, (c) if so, what were they saying to
themselves, and (d) if so, how often, on a 10-point scale (1 = few times, 10 = all the time).
Participants of the control group were also inquired regarding the possible use of self-talk in the
post-intervention competition. In particular, they were informed that athletes frequently say
things to themselves while performing and were asked to indicate after the final test (a) whether
they systematically used any form of self-talk during the experimental trial, (b) if so, what was
that, and (c) if so, to what degree (1 = not at all, 10 = all the time).
Thermal comfort and thermal sensation
Perceptions of thermal comfort and thermal sensation were assessed every 5min using the
scales by Gagge, Stolwijk, and Hardy (1967). Thermal comfort was reported on a scale from 1
(comfortable) to 5 (extremely uncomfortable) with increments of 0.5, and thermal sensation on a
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scale from 0 (unbearably cold) to 10 (unbearably hot) with increments of 1, and 5 set as
thermoneutral.
Results
Manipulation check and control measures
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Use of self-talk in training and experimental testing
Participants of the experimental group reported consistent use of self-talk during both
training (M = 8.25, SD = 1.16) and experimental testing (M = 8.75, SD = 1.04). Some
participants reported using additional motivational self-talk cues during the final assessment
(e.g., I can do it, I‟m doing well, I will make it), however not systematically (scored up to 3 on
the 10-point scale). No instructional self-talk cues were reported. Moreover, no participant from
the control group reported consistent use of self-talk during the experimental testing. Some
participants reported using motivational type cues, but not a systematic way (scored up to 4 on
the 10-point scale).
Urine specific gravity (USG)
An independent sample t-test showed no significant differences in urine specific gravity
before the onset of the experimental trial, t(14) = 0.57, p = .58, thus controlling for differences in
the levels of hydration between the two groups before the experimental trial (M = 1.016, SD =
0.003 and M = 1.015, SD =0.003, for the control and experimental groups respectively).
RPE
Two-way (2 × 6) mixed measures ANOVA with one repeated factor (time: six 5min
intervals) and one independent factor (group: experimental, control) were calculated to test for
differences in RPE throughout the 30min of exercising as a function of group. The analysis
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revealed a non-significant group by time interaction, Greenhouse-Geisser F(5, 10) = 2.09, p =
.11, ε = .65. RPE throughout the 30min of cycling exercise is displayed in Figure 1.
Experimental measures
Two-way (2 × 6) mixed measures ANOVA with one repeated factor (time: six 5min
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intervals) and one independent factor (group: experimental, control) were calculated to test for
differences in the experimental variables throughout the 30min of exercising as a function of
group.
Power output
For power output the analysis revealed a significant group by time interaction,
Greenhouse-Geisser F(5, 10) = 14.28, p < .01, partial η2 = .51, ε = .47. Examination of the
pairwise comparisons per time revealed that (a) for the control group power output increased
from min 5 to min 10 (p < .01) and then decreased steadily from min 10 to 15 (p < .01), from
min 15 to 20 (p < .01), and from min 20 to 25 (p < .01), but not significantly from min 25 to 30
(p = .35), and (b) for the experimental group power output increased from min 5 to min 10 (p <
.01) and then did not change significantly throughout the rest of the exercising time; from min 10
to 15 (p = .47), from min 15 to 20 (p = .78), and from min 20 to 25 (p = .44), and from min 25 to
30 (p = .09). Examination of the pairwise comparisons per group showed that there were no
significant differences between the two groups at min 5 (p = .06), at min10 (p = .49), at min 15
(p = .83), and at min 20 (p = .12), however a significant difference was observed for min 25 (p <
.01) and min 30 (p < .01), when the self-talk group produced more power than the control group.
Performance output throughout the 30min of cycling exercise is displayed in Figure 2.
Physiological measures
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Oxygen consumption and respiratory quotient. For oxygen consumption the analysis
revealed a significant group by time interaction, Greenhouse-Geisser F (5, 10) = 4.68, p < .05,
partial η2 = .28, ε = .35. Examination of the pairwise comparisons per time revealed that (a) for
the control group VO2 increased from min 5 to min 10 (p < .01), then did not change
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significantly from min 10 to 15 (p = .16), from min 15 to 20 (p = .17), and from min 20 to 25 (p
= .11), and decreased significantly from min 25 to 30 (p < .01), and (b) for the experimental
group VO2 increased from min 5 to min 10 (p < .01), did not change significantly from min 10
to 15 (p = .92), from min 15 to 20 (p = .32) and from min 20 to 25 (p=32), and increased from
min 25 to 30 (p < .05). Examination of the pairwise comparisons per group showed that there
were no significant differences between the two groups at min 5 (p = .93), at min 10 (p = .67), at
min 15 (p = .96), at min 20 (p = .65), at min 25 (p = .20), and at min 30 (p = .08). Oxygen
consumption throughout the 30min of cycling exercise is displayed in Figure 3. For respiratory
quotient the analysis revealed a non-significant group by time interaction, Greenhouse-Geisser F
(5, 10) = 1.88, p = .17, ε= .47.
Temperature. For core temperature, skin temperature, and muscle temperature the
analyses revealed non-significant time by group interaction effects; for core temperature,
Greenhouse-Geisser F (5, 10) = 1.07, p = .36, ε = .42; for skin temperature, GreenhouseGeisser, F (5, 10) = 0.31, p = .71, ε = .35; and for muscle temperature Greenhouse-Geisser, F (5,
10) = 0.51, p = .55, ε = .29.
Psychological measures
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For thermal comfort and thermal sensation the analysis revealed non-significant group by
time interaction effects; for thermal comfort, Greenhouse-Geisser, F (5, 10) = 2.03, p = .14, ε =
.46, and for thermal sensation Greenhouse-Geisser, F (5, 10) = 0.81, p = .47, ε = .47.
Discussion
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The self-talk literature has expanded in recent years and self-talk interventions have
attracted significant research attention. The innovative aspect of this study was examining the
effectiveness of a motivational self-talk intervention on performance in a physically, and
consequently psychologically, stressful environment (elevated heat); thus extending recent
research on the potential of the psychobiological model of endurance performance (Marcora et
al., 2008) to explain the effectiveness of motivational self-talk strategies (Blanchfield et al.,
2014), and exploring, in parallel to performance, changes on psychological and physiological
variables. Overall, the results showed that the motivational self-talk intervention group
maintained a steady output throughout the duration of the task, whereas the output of the control
group declined after the first third of the task; consequently, the self-talk group produced greater
power than the control group, in particular during the latest sections of the experimental trial. At
the same time, in line with the experimental manipulations, no differences in the patterns of
perceived exertion were recorded between the two groups throughout the trial. These findings
provide support for the effectiveness of self-talk strategies in the demanding environment of
heat, but also for the potential of the psychobiological model to justify the facilitating effects of
self-talk on performance under pressure.
Marcora et al. (2008) found that mental fatigue may limit physical tolerance
independently of any cardiorespiratory and musculoenergetic changes. Subsequently, reviewing
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the relevant literature argued that perceptions of effort are independent of afferent feedback from
skeletal muscles, heart, and lungs (Marcora et al., 2009). In the present study participants of the
two groups reported similar perceptions of exertion throughout the task, while the experimental
group produced greater output during the later stages of the task, during which oxygen
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consumption for the control group decreased and for the experimental group increased. This
evidence seems to align with Marcora et al.‟s (2009) postulations, which provided the basis for
the psychobiological model of endurance performance.
Furthermore, perception of effort is the key determinant of the psychobiological model.
When perception of effort is increased through physical or mental fatigue individuals will reduce
the pace to compensate for that change in perceived effort. Accordingly, to maintain a steady
RPE participants of the control group reduced their pace, thus producing lower output; whereas
this was not the case for participants of the self-talk group. The model also postulates that any
physiological or psychological strategies that can help regulating individuals‟ perceptions of
effort can benefit endurance performance. The use of motivational self-talk seems to have played
this role, as participants of the self-talk group, in contrast to those of the control group,
maintained their pace while keeping a steady RPE. Blanchfield et al. (2014) in their time to
exhaustion study argued that the perceptual effect of motivational self-talk delayed the point at
which participants felt exhausted and terminated the task. In this study, it could be argued that
motivational self-talk helped participants maintain steady RPE despite the effects of heat that has
been shown to increase RPE.
The analysis regarding oxygen consumption, revealed a significant group by time
interaction effect. Oxygen consumption gradually decreased for the control group, whereas for
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the self-talk group remained stable and increased during the late stages of the trial. Despite the
lack of significance in the between subjects comparisons, the pattern identified for VO2 in the
within subjects comparisons resembled those of power output. Increased oxygen demands during
exercise in the heat were recently highlighted as one of the determinants of performance-related
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behavior (Flouris & Schlader, 2015). To maintain perceptions of effort steady under conditions
of elevated oxygen demands, participants of the control group reduced effort input during latest
stage of the task. In contrast, for participants of the experimental group, who maintained a steady
output throughout, increased oxygen demands were evidenced during the latest stage of the task.
The results showed no significant differences between the two groups for changes in
respiratory quotient, which reflects the body‟s muscles substrate utilization (Colak & Ozcelik,
2002). In general, both groups were primarily reliant on carbohydrates during the 30min cycling
protocol in the heat. Also, no significant differences between the two groups were found for
changes in body temperature and thermal perceptions. Core, skin, and muscle temperatures
increased throughout the trial for both groups, and so did thermal sensation and thermal comfort,
which have been associated with increased body temperature, increased skin temperature, and
sweating (Gagge et al., 1967). Bruck and Olschewski (1987) found that in hot conditions, the
motivation to continue exercising and the drive to exercise gradually declined. Hartley et al.
(2012) concluded that the thermal environment influences voluntary power output and
physiological responses while cycling at a constant perceived effort. The thermal stress that was
generated through the experimental conditions in this experiment may have caused the decreased
output produced by the control group. In contrast, the self-talk group, managed to overcome the
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effect of thermal stress on perceived effort, despite the similar to the control group thermal
perceptions, and this led to finally achieving greater output.
Endurance tasks are best performed at higher levels of arousal (Gould, Greenleaf, &
Krane 2002; Landers & Arent, 2010). Accordingly, motivational self-talk, which focuses on
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increasing effort, energy and positive affect (i.e., arousal), can have significant impact on
endurance cycling performance in the heat, as a high positive effect size was identified (d = .79).
Hatzigeorgiadis et al. (2011) in their meta-analytic study found an overall moderate positive
effect size (d = .48), and also a moderate effect size for learned tasks (d = .41), and a lower effect
for tasks requiring strength and endurance (d = .26). Self-talk seemed to be effective in
enhancing power output in this laboratory experiment to a larger extent, as identified by the
effect size, thus suggesting that the effectiveness of self-talk strategies (particularly motivational
self-talk cues) may be more effective for endurance performance in extreme environments.
The experimental design was developed on the principle of keeping participants‟ RPE
stable across the trial. In real-life exercise settings, athletes determine effort input almost
completely based on their perceived exertion. Normally, this is not the case in a controlled
laboratory environment where participants receive a multitude of information and input and/or is
requested to exercise at a specific intensity. In this light, the “RPE clamp” protocol is one of the
advantages of this study, as it allowed us to truly test voluntary central control of performance.
Furthermore, the present study adopting a design different to the time-to exhaustion and the
time-trial designs that have been adopted in previous studies (Barwood, Corbett, Wagstaff,
McVeigh, & Thelwell, 2015, Blanchfield et al., 2014; Wallace et al., 2016), strengthens the
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support for the psychobiological model of endurance performance through a different
methodological perspective.
Two methodological issues should be identified at this point to address potential
limitations of this research; the limited sample size and the between-subject design that was
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adopted. With regard to the sample, the requirements of the experimental procedures involving
extended physiological measures and, importantly, the physical demands of the task was
apparently a restricting factor for the recruitment of participants, which limited our sample and
subsequently the power of the study. With regard to the design, adopting a repeated design
including a baseline assessment in similar conditions would have restricted error variance
associated with individual variability. Given the demands of the task we opted for a between
subject design, yet performed the VO2peak test on the same cycloergometer to control for
individual differences at baseline. Moreover, including a sham group would have further
increased our confidence for the findings; nevertheless, during the training sessions participants
of both experimental and control groups received equal time of treatment, thus the possibility of
a social facilitation effect is rather weak. Finally, from a theoretical perspective, a limitation of
this and other studies testing the tenets of the psychobiological model of endurance performance
is the lack of controlling measures regarding potential motivation that is also considered to
influence endurance performance. Thus, future studies should adopt design that either control or
assess participants‟ motivation towards goal attainment.
Despite the above limitations the present study provides valuable evidence for the
understanding of self-talk effectiveness in endurance performance, offers support for the
psychobiological model of endurance performance as a potential self-talk mechanism, and
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provides important directions for self-talk research. In addition to the recommendation for future
research evolving from the limitations of the study, future research should also consider other
potential mechanisms that may operate to explain the facilitating effects of self-talk on
endurance performance, as the different self-talk mechanisms are likely to operate in tandem
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(Hardy, 2006). Towards this direction, but also considering the importance of multidisciplinary
approaches, the inclusion of psychophysiological measures, such as heart rate variability will
help to examine the functioning of the autonomous nervous system and its relationships with
perceptions of exertion. Moreover, considering findings linking perception of effort to response
inhibition processes suggesting that these two functions involve similar brain areas (Pageaux et
al., 2014), neurophysiological measures involving self-talk related brain activation would be of
particular interest for the understanding of self-talk effectiveness.
From an applied perspective, the implications of the findings are important. The heat is
widely recognized as a performance hindering factor for endurance tasks. Athletes compete more
and more often in environmentally demanding conditions, following the global increase of
environmentally extreme phenomena and in particular heat, but also the quest for challenge (e.g.,
the yearly Marathon de Sables in Morocco). Therefore, strategies that can help regulate
perceptions and subsequent efforts, such as motivational self-talk, are likely to facilitate
performance. Practitioners, coaches and athletes should therefore develop and train self-talk
plans for to be prepared to deal with expected, and importantly unexpected, hot environmental
conditions, to maximize tolerance and minimize performance losses.
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Table 1. Descriptive statistics for all variables measured during the cycling trial.
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min5
RPE
min10
M
output (W)
VO2
M
SD
0.8
0
1
77.0
2.8
103.0
12.5
98.4
16.1
92.4
19.7
87.7
24.9
89.2
27.9
6
3
5
3
4
4
4
8
5
6
5
8
24.5
4.7
9
5
0.75
14.4
0.95
3
5.09
0.72
5.29
SD
0.80
6.44
SD
0.95
3
30.1
6
M
15.1
3
31.1
1
M
14.6
4
31.8
31.94
SD
min30
13.5
14.6
M
min25
SD
RQ
SD
min20
M
14.19
Power
min15
30.7
8.37
0
9.23
4
0.0
0.90
1.01
0.08
34.97
0.96
0.99
0.08
0.98
0.06
0.96
0.06
0.96
0.07
8
Temperatu
re – Core
Temperatu
34.7
0.9
35.2
35.8
1.09
35.8
0.99
0.82
1
2
0
3
2
9
33.7
0.4
34.9
35.2
35.5
35.8
1
8
36.2
0.3
34.46
re – Skin
35.5
0.98
0.60
0.67
1
0.71
9
0.73
7
0.83
9
Temperatu
re –
36.8
36.65
3
0.51
5
36.9
0.63
5
37.0
0.66
3
37.1
0.82
6
0.88
8
Muscle
Thermal
0.8
2.43
comfort
2.81
0.89
3.09
0.84
3.37
0.86
3.71
0.89
3.84
0.78
3
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Thermal
0.5
7.19
sensation
7.63
0.80
8.06
0.68
8.25
0.57
8.63
0.50
8.69
0.60
4
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Figure Captions
16
RPE
control group
15.5
15.5
self-talk group
15
14.75
15
14.88
14.75
14.5
14
14.25
13.75
14.13
14.38
14.25
14.13
13.5
13.25
13
12.5
12
min 5
min 10
min 15
min 20
min 25
min 30
Figure 1. Group by time interaction for RPE.
Figure 2. Group by time interaction for power output.
Figure 3. Group by time interaction for VO2.
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120
110
Power output
control group
108.75
self-talk group
105.75
99.38
100
101.25
100.13
102.38
97.5
90
80
78.38
84.75
75.75
70
73.13
69.75
60
min 5
min 10
min 15
31
min 20
min 25
min 30
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40
VO2
control group
37.5
self-talk group
35,08
35
33,58
32,82
32.5
30
31,57
31.9
32
31,72
30,32
27.5
25
22.5
27,74
24,11
26.4
23,88
20
min 5
min 10
min 15
32
min 20
min 25
min 30
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