Acceptance and Commitment Therapy
Improves Exercise Tolerance in
, DENNIS JENSEN
, JAMIE CASSOFF
, FEI GU
, and BA
Department of Psychology, McGill University, Montreal, Quebec, CANADA; and
Department of Kinesiology and Physical
Education, McGill University, Montreal, Quebec, CANADA
IVANOVA, E., D. JENSEN, J. CASSOFF, F. GU, and B. KNA
¨UPER. Acceptance and Commitment Therapy Improves Exercise
Tolerance in Sedentary Women. Med. Sci. Sports Exerc., Vol. 47, No. 6, pp. 1251–1258, 2015. Purpose: To test the efficacy of an acute
intervention derived from acceptance and commitment therapy (ACT) for increasing high-intensity constant work rate (CWR) cycle
exercise tolerance in a group of low-active women age 18–45 yr. The secondary goals were to examine whether ACT would reduce
perceived effort and improve in-task affect during exercise and increase postexercise enjoyment. Methods: In a randomized controlled
trial, 39 women were randomized to either the experimental (using ACT-based cognitive techniques and listening to music during the
CWR exercise tests) or a control group (listening to music during the CWR exercise tests). Before (CWR-1) and after the intervention
(CWR-2), participants completed a CWR cycle exercise test at 80% of maximal incremental work rate (W
) until volitional exhaustion.
Results: On average, ACT (n= 18) and control (n= 21) groups were matched for age, body mass index, weekly leisure activity scores,
(all P90.05). Exercise tolerance time (ETT) increased by 15% from CWR-1 to CWR-2 for the ACT group (392.05 T146.4 vs
459.39 T209.3 s; mean TSD) and decreased by 8% (384.71 T120.1 vs 353.86 T127.9 s) for the control group (P= 0.008). RPE were
lower (e.g., by 1.5 Borg 6–20 scale units at 55% of ETT, Pe0.01) during CWR-2 in the ACT versus that in the control group. By
contrast, ACT had no effect on in-task affect. Exercise enjoyment was higher after CWR-2 in the ACT group versus that in the control
group (PG0.001). Conclusions: An acute ACT intervention increased high-intensity ETT and postexercise enjoyment and reduced
perceived effort in low-active women. Further investigations of ACT as an effective intervention for enhancing the established health
benefits of high-intensity exercise need to be provided. Key Words: ACCEPTANCE AND COMMITMENT THERAPY, EXERCISE
TOLERANCE, RPE, EXERCISE ENJOYMENT
Physical inactivity is an independent risk factor for
increased cardiometabolic morbidity and mortality
(30). Nevertheless, only 3.2% of women in North
America meet the recommended physical activity guidelines
(46). High-intensity exercise offers comparable or superior
health benefits (e.g., improved cardiorespiratory fitness) as
low- or moderate-intensity exercise in both clinical and
healthy populations (16). In fact, patients with cardiac dis-
eases gain equivalent health benefits after a 12-wk low-
volume, high-intensity intervention (10 1-min cycling
intervals at È90% of maximal work rate [W
]) compared to
a less time-efficient moderate-intensity intervention (30 min
of continuous cycling at È60% W
) (9). In addition to
time efficiency, recent research showed that 10 wk of high-
intensity exercise training was associated with a 2.3-fold
greater improvement (+17.9% vs 7.9%) in V
patients with coronary artery disease than 10 wk of training
at moderate intensities (40).
Theoretical and empirical research, however, suggests
that participation in high-intensity activities may be under-
mined by perception of effort (as measured by RPE) (5) and
negative affect (as measured by pain ratings or the Feeling
Scale [FS]) (20), particularly among women (33,41). The
psychobiological model of endurance performance (37),
based on the motivational intensity theory (7), suggests that
exercise tolerance is based on the perception of effort (i.e.,
how hard, heavy, and strenuous exercise is being perceived)
(36) and on potential motivation (i.e., the maximum effort an
individual is willing to exert). Consequently, factors that can
target either or both components of the model may have the
potential to increase exercise tolerance (e.g., Blanchfield et al.
 and Marcora et al. ). In regards to affective responses
to exercise, the Dual-Mode Model (DMM) (10), based on
the hedonic theory of motivation (11), states that pleasant or
unpleasant responses during exercise are determined by the
Address for correspondence: Elena Ivanova, M.A., Department of Psychol-
ogy, McGill University, 1205 Dr. Penfield Avenue, Stewart Biology Building,
Montreal, QC, Canada H3A 1B1; E-mail: email@example.com.
Submitted for publication July 2014.
Accepted for publication September 2014.
Supplemental digital content is available for this article. Direct URL citations
appear in the printed text and are provided in the HTML and PDF versions of
this article on the journal’s Web site (www.acsm-msse.org).
MEDICINE & SCIENCE IN SPORTS & EXERCISE
Copyright Ó2014 by the American College of Sports Medicine
Copyright © 2015 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
interaction of cognitive factors (e.g., self-efficacy) and in-
teroceptive feedback (e.g., physical discomfort) during ex-
ercise. The exercise intensity influences the relative salience
of each factor in regulating the exercise-related affective
responses (10). Primarily, an increase in exercise intensity
(e.g., above the ventilatory threshold) is accompanied by a
decline in effect for most individuals because the intero-
ceptive cues stimulated by the exercise become more salient
(10). Consequently, to effectively manage the demands of
exercising, optimal techniques that improve affective re-
sponses to exercise and reduce perceived effort need to be
identified, with the aim to sustain exercise tolerance at in-
tensities that confer health benefits (e.g., Rognmo et al.
). Research efforts have so far focused on the use of
diverting attention/distraction (e.g., listening to music) and
association techniques (e.g., self-talk with a focus on the
exercise experience), with some evidence that distraction
techniques can have positive effects on RPE and in-task
effect at low and moderate intensities (e.g., 60% and 75%
of maximal HR) (6), whereas association techniques may
decrease perceived effort at higher intensities (e.g., 80%
of maximal work rate) (4). As the exercise intensity in-
creases (e.g., 90% V
) (45), distraction techniques such
as music become less effective at reducing perceived effort
and maintaining exercise tolerance. Indeed, a comprehen-
sive review of the literature showed that music has limited
effects on reducing perceived effort during exercise at in-
tensities above the anaerobic threshold (29). According
to the effort-related model (44), sustaining attention on an
external stimulus like music becomes effortful during high-
intensity workloads owing to difficulties with diverting
attention away from interoceptive (sensory) feedback. It
follows that alternative cognitive strategies to distraction are
required to help individuals better cope with the perceived
effort during strenuous exercise. An important study by
Blanchfield et al. (4) recently found that 12 recreationally
) men and women
randomly assigned to a 2-wk motivational self-talk (i.e., an
associative technique) intervention reported greater mean
improvements in perceived effort and exercise duration
during high-intensity constant work rate (CWR) cycle ex-
ercise testing at 80% of maximal work rate (W
) than a
group of 12 age-, sex-, and V
-matched adults ran-
domly assigned to usual exercise without self-talk inter-
vention control group. It remains to be determined, however,
whether similar improvements in perceived effort at high-
intensity exercise performance can be achieved through
an acute (single-session) application of cognitive techniques
in physically inactive women, namely, women who are most
in need of such improvements (e.g., Schaeffer et al. ).
Acceptance and commitment therapy (ACT) is a form of
psychotherapy (21) that is widely used in clinical settings for
the treatment and management of psychological disorders,
and more recently, it has been applied to health-related be-
haviors, including cigarette smoking cessation (17), self-
management of diabetes (19), and weight loss (15). One of
the core assumptions in ACT is that negative and unpleasant
feelings and experiences are neither good nor bad, but rather
a facet of human life (21). Thus, acceptance-based tech-
niques focus on increasing an individuals’ willingness to
experience aversive feelings, thoughts, and sensations, with-
out trying to change or eliminate them (8,34). We proposed
that acceptance-based techniques can help to improve af-
fective responses, reduce perceived effort, and increase ex-
ercise tolerance during a high-intensity exercise test because
ACT teaches individuals how to accept and defuse from the
unpleasant internal experiences (e.g., exercise-related pain),
in turn, for a behavior that they value (i.e., physical activity).
Empirical evidence provides convincing support for the use
of cognitive techniques derived from ACT (22) rather than
suppression or distraction techniques (e.g., Masedo and
Esteve ) in helping individuals to tolerate physical dis-
comfort and pain. For example, a study of 219 young adults
by Masedo and Esteve (38) randomized to the ACT inter-
vention group were È60% and 20% more tolerant to the
pain and distress associated with the cold pressor test than
individuals randomized to the suppression and spontaneous
coping intervention groups, respectively. In light of these
findings, the general aim of our theoretically grounded and
randomized study was to examine the potential benefits of
two cognitive techniques derived from ACT on exercise
tolerance time (ETT) during a high-intensity cycle exercise
test in apparently healthy, young, and low-active women.
Our primary aim, therefore, was to test the hypothesis that a
single session of ACT training will improve high-intensity
) CWR cycle ETT in these women. The sec-
ondary aims were to examine whether these improvements
in ETT are accompanied by improvements in perceived ef-
fort, in-task affect, and postexercise enjoyment.
Thirty-nine nonsmoking, low-active, and nonpregnant or
nursing women age 18–45 yr (23 T5 yr; mean TSD) with no
known or suspected cardiometabolic, pulmonary, and/or
musculoskeletal disorder(s) and not taking psychotropic med-
ications took part in this study.
Experimental Design, Randomization, and Procedures
As illustrated in Figure 1, this was a single-center, pretest–
posttest, parallel-group, randomized controlled trial. The study
protocol received ethical approval from the Institutional Re-
view Board of the Faculty of Medicine at McGill University
(IRB no. A00-B39-12B) in accordance with the Declaration
After providing written informed consent, eligible individ-
uals recruited by word of mouth and posted announcements
in Montreal and the surrounding areas and participated in two
testing visits separated by Q48 h and completed within 1 wk.
http://www.acsm-msse.org1252 Official Journal of the American College of Sports Medicine
Copyright © 2015 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
Participants were asked to avoid caffeine and/or energy drinks
before testing and to not exercise 24 h before testing.
Visit 1 included the completion of baseline questionnaires
followed by an exercise test until volitional exhaustion on
an electronically braked cycle ergometer (Ergoline 800s;
SensorMedics, Yorba Linda, CA) for familiarization pur-
poses and for the determination of W
. Incremental exer-
cise tests consisted of a steady-rate resting period of 3 min
followed by 25-W increases in work rate (starting at 25 W)
to the point of volitional exhaustion: W
was defined as
the highest cycle work rate the participant was able to sus-
tain for Q30 s. The criterion for stopping the incremental
exercise test was volitional exhaustion, which was assessed
by 1) instructing the participants to give a clear indication
(verbal or by waving their hand) that they have reached their
absolute maximum effort and/or 2) by informing the par-
ticipant that the test will be terminated if the pedal cadence
falls below 50 revolutions per minute (rpm). Verbal encour-
agements were provided.
Visit 2 included two CWR cycle exercise tests at 80%
until volitional exhaustion: one before (CWR-1) and
another after (CWR-2) the ACT or control intervention (see
below). The time between the two CWR exercise tests was
approximately 50 min (È40-min intervention and È10-min
preparatory and waiting period); refer to Figure 1 for a flow-
chart of the study design. High-intensity CWR cycle exercise
tests to exhaustion were selected because they permit opti-
mal control of workload and are as sensitive as cycle time-
trial tests to detect changes in ETT (our primary outcome
variable) in response to an intervention (1). The criterion for
stopping the submaximal incremental exercise tests was
volitional exhaustion, and the same instructions were pro-
vided to participants as during the incremental exercise test
(Visit 1). Verbal encouragements were not provided. CWR
exercise tests consisted of 1) a steady-rate resting period of
3 min, 2) a 1-min warm-up at 25% W
while listening to
music followed by a step increase in work rate to 80% W
with participants cycling to volitional exhaustion while lis-
tening to music, and 3) a 3-min cool-down period. Partici-
pants provided ratings to the FS, the Felt Arousal Scale (FAS),
and Borg_s 6–20 category ratio scale of perceived effort at
rest, within the last 15 s of every second minute during ex-
ercise and immediately after peak was reached. Similarly, par-
ticipants were asked to identify whether they had an associative
or distractive thought using the Association/Dissociation Scale
within the first 15 s of every second minute during exercise
and immediately after peak was reached. The scales presented
during the exercise tests were shown in a fixed order. Imme-
diately after the 3-min cool-down period, participants com-
pleted the FS, FAS, Physical Activity Enjoyment Scale (PACES),
and responded to the manipulation check items, with all the
scales presented in a fixed order. The manipulation check
items included the following: 1) ‘‘How confident are you that
you learned the acceptance-based techniques that we taught
you?,’’ with responses ranging from 1 (not at all confident) to
5 (very confident); and 2) ‘‘How frequently did you use the
acceptance-based techniques during the last cycle exercise
test?,’’ with responses ranging from 1 (never) to 5 (all the
time). ETT was defined as the duration of loaded pedaling.
Online randomization software (www.randomization.com)
was used to assign eligible participants to either of the two
interventions upon arrival to the laboratory for testing. The
research assistants conducting CWR-1 and CWR-2 exercise
tests were blinded to the group allocation, whereas the ACT
interventionist (E.I.) was not present during exercise testing
at Visit 2.
ACT intervention. Participants randomized to the ex-
perimental group received a one-time È40-min intervention
(and additional È10 min in preparatory/waiting period) in
which they were taught cognitive defusion and acceptance
techniques for coping with aversive physical discomfort
(e.g., leg discomfort) and negative affect (e.g., boredom)
during CWR-2. The intent of cognitive defusion was to help
participants disentangle their physical sensations (e.g.,
burning legs) from their thoughts (e.g., ‘‘I must stop exercis-
ing’’) and behaviors (e.g., quit exercising). Acceptance tech-
niques were used to help increase participants_willingness
to experience consequences of a valued behavior (e.g., exer-
cising) that may carry unpleasant physical sensations, without
trying to change, control, or eliminate them (22). To illustrate
both techniques, metaphors (adapted from Hayes et al. )
and an experiential exercise involving the use of an ice
cube were utilized. The manual is available as a supplemental
FIGURE 1—Flowchart diagram of the trial.
ACT TECHNIQUES AND EXERCISE DURATION Medicine & Science in Sports & Exercise
Copyright © 2015 by the American College of Sports Medicine. Unauthorized reproduction of this article is prohibited.
material online. [See table, Supplemental Digital Content 1,
Acceptance-based techniques (defusion + acceptance),
No-ACT intervention. Participants randomized to the
no-ACT intervention control group watched a short video and
created concrete goals for when, where, and how they would
increase their overall physical activity levels upon study
completion. Time spent with the interventionist (È40 min)
and the preparatory and waiting period (È10 min) was
matched to that of the ACT condition. After È50 min, the
participants completed CWR-2 and were asked to refer to
the music as a means of coping with the high intensity.
During both CWR exercise tests, the participants listened
to music (using headphones) that they selected according to
their own preference from four genres: Pop, Hip-Hop and
R&B, Electronic Dance, and Alternative Rock. Twelve songs
from each of the aforementioned genres were selected from
the Billboard Canadian Hot 100 (2011–2013) and scanned
using BeatScanner software: only songs with a tempo of
135–140 beats per minute (considered optimal for high-
intensity exercise) (28) were included. Eligible songs were
then purchased from Yes!Music Fitness, downloaded to
iTunes, and synchronized to an Apple iPod Touch.
HR. This was monitored at rest and during exercise using
a Polar HR monitor with chest band (Lachine, QC, Canada).
RPE. These were measured using Borg_s 6–20 category
ratio scale (5), where ‘‘6’’ represents ‘‘no exertion at all’’ and
‘‘20’’ represents ‘‘maximal exertion.’’
In-task affective responses. The circumplex model
guided the selection of measures used to repeatedly assess
affect during the CWR exercise tests. Specifically, affect can
be defined by two dimensions: 1) affective valence (pleasure–
displeasure) assessed by the FS (20), with responses ranging
from j5 (very bad) to +5 (very good); and 2) perceived
activation (low-high) assessed using the FAS (42), with re-
sponses ranging from 1 (low arousal) to 6 (high arousal). Both
the FS and FAS are single-item measures that can be repeat-
edly administrated over a short period. The FS demonstrates
strong concurrent and discriminant validity (12,42).
Attentional focus. The Association/Dissociation Scale
(43) is a 10-point bipolar scale, with 1 representing associa-
tion (e.g., thoughts related to the exercise) and 10 representing
dissociation (e.g., distraction-related thoughts). This scale has
established concurrent validity (3).
Physical activity enjoyment scale. The PACES (31),
an 18-item measure incorporating a 7-point Likert scale
(e.g., 1 [It is very pleasant or I dislike it] to 7 [It is no fun at
all or I like it]), was administered immediately after the cool-
down period of CWR-1 and CWR-2. The PACES has good
predictive and discriminant validity (31).
All statistical analyses were implemented by SAS 9.3, and
power analysis was conducted using G*Power 3 (13). On
the basis of past findings on the effectiveness of ACT tech-
niques on promoting physical activity adherence (8), we
determined a priori that Q36 individuals (Q18 per group)
were required to detect a moderate effect size of G
on our primary outcome variable (ETT) with >and power
set at 0.05 and 0.80, respectively. The ETT variables were
positively skewed, and natural log transformations were
applied to the original variables before the main analysis
(14). Owing to the variability in ETT for each participant, in-
task affect (FS), activation (FAS), RPE, and association/
dissociation were generated through linear interpolations
between obtained adjacent values and anchored at baseline,
20% of ETT, 40% of ETT, 55% of ETT, and at peak exercise.
Baseline characteristics between the groups were com-
pared using independent-sample t-tests and analyzed only
for the participants who completed all testing sessions. Mixed-
effect model was estimated using PROC MIXED, and con-
trasts were specified in the model to compare ETT from
CWR-1 and CWR-2 both within and between groups and
to test the associations between the groups (ACT vs control)
and the repeated measurements during CWR-2 (RPE, FS,
FAS, association/dissociation) and immediately after the
CWR-2 (FS, FAS, and PACES). Owing to the technical dif-
ficulties in data collection, some outcome variables contained
missing values, which were accommodated for by using the
full information maximum likelihood estimator in PROC
MIXED. An advantage of using the full information maxi-
mum likelihood estimator is that the observation in which
the outcome variable is missing can be used in parameter
estimation. Otherwise, in conventional repeated-measures
ANOVA, the observation would be deleted. Also, the mixed-
effect model gives the flexibility of specifying a patterned
covariance structure for model residuals. In this study, we
specified a first-order autoregressive AR(1) structure in PROC
MIXED for residuals. The AR(1) structure is appropriate for
data collected from repeated measures designs (27).
Forty-seven participants were recruited. Of these, seven
participants failed to complete all testing sessions (e.g., be-
cause of dizziness) and were excluded from data analysis.
One participant was excluded because she reported engaging
in regular physical activity for 96 months before study par-
ticipation. Thirty-nine participants were thus included in the
analyses (Fig. 1): ACT (n= 18) versus control (n= 21).
These participants had an average weekly leisure activity
score (Godin-Leisure Time Exercise Questionnaire) of 13 T
12 units, indicating that they were insufficiently active,with
24 units or more reflecting sufficiently active (18). The ma-
jority of the participants identified as East Asian (44.7%) and
white (39.5%), with the remaining participants identified as
http://www.acsm-msse.org1254 Official Journal of the American College of Sports Medicine
South Asian (13.2%), African (2.6%), Aboriginal (2.6%),
Biracial (5.3%), or Middle Eastern (5.3%). Body mass index
, peak incremental cycle HR (HR
), and peak
incremental cycle RPE for all 39 participants were 21.7 T
(range = 14.8–39.7 kgIm
), 130 T30 W (82% T
16% predicted; range = 49%–119%; ), 179 T15 beats per
minute (96% T7% predicted; range = 68%–109%), and 18.0 T
1.5 (range = 14–20) Borg 6–20 scale units, respectively. These
findings suggest that, on average, our participants were normal
weight, low-active, and that they gave a maximal/near-maximal
effort during exercise at Visit 1. The ACT and control groups were
well matched for age (24 T6vs22T5 yr), BMI (22.6 T5.4
vs 20.9 T2.4 kgIm
), average weekly leisure activity scores
(11 T12 vs 15 T12 units), W
(83% T18% vs 81% T15%
(94% T9% vs 97% T5% predicted), cycle
work rate at 80% W
(100 T23 vs 108 T25 W), and HR
responses to CWR-1 and CWR-2 (all P90.05).
Manipulation check for the ACT group. Participants
understood the ACT-based techniques and used them fre-
quently during CWR-2: 83% of the ACT group reported feel-
ing ‘‘confident’’ or ‘‘very confident’’ that they learned the ACT
techniques. When asked if they frequently applied the tech-
niques during the CWR-2 exercise test, 88.9% endorsed op-
tions 4 (no verbal anchor) and 5 (representing ‘‘all the time’’)
on the 5-point Likert scale.
ETT. As hypothesized, a significant group–time inter-
action was observed for ETT: F
= 0.05 (see Fig. 2). The ETT at CWR-1 was 392.05 T
146.4 and 384.71 T120.1 s for the ACT and control groups,
respectively (P= 0.98). After the intervention, ETT was
higher for the ACT group (459.39 T209.3 s) than for the
control group (353.86 T127.9 s): post hoc planned contrasts
indicated that ETT increased by 15% from CWR-1 to CWR-2
for the ACT group (F
=4.94,P= 0.03) and decreased by
8% for the control group (P=0.09).
RPE. As expected, a significant group–time interaction
was observed for RPE: F
=5.92,P= 0.0002, pseudo R
0.81 (see Fig. 3). Planned contrasts revealed a significant
difference in Borg 6–20 scale RPE values between the ACT
and control group at 40% (12.4 T2.8 vs 14.2 T2.2 units;
= 9.81, P= 0.002) and 55% (14.0 T2.8 and 15.4 T2.3
Borg 6–20 scale units; F
= 6.70, P= 0.01) of ETT.
Attentional focus, in-task affect, and exercise
enjoyment. Contrary to our expectations, a group–time
interaction for in-task affect (F
= 1.01, P= 0.41) or
activation levels during CWR-2 and after immediately post
= 1.42, P= 0.22) were not observed. By
contrast, a significant group–time interaction was observed
for perceived exercise-related enjoyment (F
= 21.61, PG
0.0001, pseudo R
= 0.172): pairwise comparisons showed
no significant change in exercise enjoyment post CWR-1 (P=
0.68), whereas exercise enjoyment after CWR-2 was signif-
icantly higher in the ACT group versus that in the control
group (95.6 T13.7 vs 78.6 T18.9 arbitrary units; F
P= 0.008). The exercise enjoyment scale further demon-
strated high internal consistency: Cronbach >was 0.90 and
0.96 for CWR-1 and CWR-2 exercise tests, respectively.
Lastly, a group–time interaction was not observed for at-
tentional allocation during CWR-2 (F
To our knowledge, this is the first randomized controlled
study to show that an acute ACT intervention improved
high-intensity cycle ETT by È15% in apparently healthy,
young, normal-weight, and low-active women. In keeping
with the psychobiological model of endurance (37), the
present study further showed that ACT-induced improve-
ments in ETT were associated with improvements inperceived
effort and ratings of postexercise enjoyment. Furthermore, our
findings complement the results of a randomized trial by
Blanchfield et al. (4) who recently showed that a 2-wk mo-
tivational self-talk intervention improved both ETT and
perceived effort during CWR cycle exercise testing at 80%
in healthy, young recreationally active men and women.
In addition, although DMM based on hedonic theory of ex-
ercise motivation (10) provides an important understanding
of the mechanisms associated with affective responses dur-
ing exercise, these findings demonstrate that DMM cannot
FIGURE 2—Exercise tolerance time means TSEM for the control and
ACT condition at CWR-1 (preintervention 80% W
exercise test) and
CWR-2 (postintervention 80% W
FIGURE 3—Mean RPE at baseline, 20%, 40%, and 55% of exercise
tolerance and peak (100%) for the control and ACT condition during
CWR-2 (postintervention 80% W
ACT TECHNIQUES AND EXERCISE DURATION Medicine & Science in Sports & Exercise
fully predict exercise tolerance among low-active individuals.
The differential effect of affect and perceived effort on exer-
cise behavior is elucidated by the fact that different theoretical
and neurobiological mechanisms influence perceived effort
and affective responses. Specifically, based on DMM, affec-
tive responses are influenced by afferent feedback from sen-
sory receptors (e.g., chemoreceptors) that reach the affective
centers of the brain (e.g., amygdala) (10), whereas perception
of effort is generated by corollary discharges from motor to
sensory areas of the cerebral cortex (35). The role of ACT in
influencing the neurobiological signals associated with per-
ceived effort remains to be determined by using neurophysi-
ological methods and study designs. Moreover, future research
needs to establish the long-term effect of these findings in
relation to improving exercise adoption, maintenance, and,
ultimately, health outcomes. The psychobiological model of
exercise (37) based on the motivational intensity theory (7)
can be used to guide this research. On the basis of the model,
hypotheses can be generated with regard to how perception of
effort may affect exercise-related decisions, for instance
whether to engage or not with exercise, or when to disengage
during exercise (i.e., volitional exhaustion).
An increase in high-intensity exercise tolerance among
low-active women carries a twofold significance. First, a
pervasive barrier to physical activity is lack of time (26),
thereby prolonging exercise tolerance at high intensities may
be a time-efficient alternative to low- and moderate-intensity
activities with potentially important implications for adher-
ence (32). Second, increasing exercise duration at high in-
tensities (e.g., 80% W
) may confer important health
benefits including improvements in insulin sensitivity in
sedentary, overweight, or obese adults (24) and in aerobic
working capacity/cardiorespiratory fitness (e.g., V
and cardiometabolic risk factors (e.g., blood pressure) in
healthy and clinical populations (9,16,23). Considering that
ACT increased high-intensity exercise tolerance by È15%,
application of this simple psychological intervention with
sedentary populations may be associated with vital improve-
ments in health outcomes. Randomized, controlled, and lon-
gitudinal studies are necessary in this regard.
Another finding of the present study that may carry im-
portant implications for health and adherence was that the
use of ACT techniques reduced perceived effort at an in-
tensity of exercise at which distractive techniques (e.g.,
music) have previously been shown to become less effective
in reducing perceived effort (29). It is noteworthy that,
contrary to our expectations, the ACT techniques did not
improve in-task affect, which is in support of the DMM,
stating that affect is predominantly unpleasant during exer-
cise above the ventilatory threshold (10). Whether or not
ACT techniques such as those used in our study are capable
of improving in-task affect during exercise at lower inten-
sities (e.g., 50% W
) requires further investigation.
The mechanism explaining the observed changes in per-
ceived effort using ACT techniques remains less clear. The
finding that perception of effort was reduced after the ACT
training may be explained by motivational intensity theory
(7,49), which postulates that actual effort is withheld for
difficult tasks because ‘‘Ieffort requirements exceed what
the performer is capable of doing’’ (49, p. 686). Hence, the
individual discontinues effort because it is perceived as in-
effective, as opposed to because the individual is not willing
to engage in the behavior (49). The ACT techniques thus
may have reduced perception of effort indirectly through
increasing the perceived ability to perform the high-intensity
exercise task (4). This hypothesized cognitive mechanism,
however, needs to be examined in future research investi-
gations. Differences in attention allocation cannot account
for the perception of effort because both groups were asso-
ciating (focusing on the physical sensations) throughout the
exercise session, as opposed to distracting. This supports the
Effort-Related Model, which states that association pre-
dominates at high intensities (44). This model further sug-
gests that both association and diverting attention may
reduce perceived effort at low and moderate intensities but
not at high intensities. In contrast, research on individual
differences in attention allocation shows that individuals
whose dominant attentional style is association report lower
perceived effort at high intensities than individuals whose
dominant attentional style is dissociation (e.g., 85% of HR
reserve) (25). To address the inconsistent findings on the
efficacy of association during high-intensity exercise, future
research needs to identify the cognitive mechanisms (e.g.,
active association with cognitive interpretations imposed on
the physiological sensations vs passive association of mon-
itoring body sensations) that lead to the effectiveness of as-
sociation techniques. ACT techniques may be one possible
cognitive mechanism with implications for enhancing asso-
ciation during high-intensity exercise. Lastly, the present
study results also suggest that use of ACT techniques may
improve postexercise enjoyment, even in the absence of var-
iations in music and exercise setting (i.e., external factors that
may affect enjoyment), which may have important implica-
tions for physical activity adoption and adherence (48). Fu-
ture research efforts are required to further understand the
relation between perceived effort and postexercise enjoy-
ment and their relationship to exercise adherence.
The CWR exercise tests until volitional exhaustion were
completed before and after intervention on the same day,
which had the potential to undermine the effect of the
ACT intervention on measured parameters by exacerbating
perceived effort and decreasing enjoyment and exercise
tolerance during CWR-2 versus CWR-1 in this sample of
low-active women. Therefore, the same-day testing may
have undermined the È15% increase in ETT and the RPE.
Nevertheless, women randomly assigned to the ACT inter-
vention demonstrated significantly greater mean improve-
ments in ETT, perceived effort, and exercise enjoyment
from CWR-1 to CWR-2 than those women randomized to
http://www.acsm-msse.org1256 Official Journal of the American College of Sports Medicine
the no-ACT intervention control group. Furthermore, al-
though the exercise test used in this study is not relevant to
the current exercise guidelines (47), an improvement in ex-
ercise tolerance at high intensities can help individuals with
high-intensity interval training, which can be a time-efficient
alternative to exercising at lower intensity levels for longer, and
it is associated with equivalent health improvements (e.g., Gibala
et al. ).
Women were characterized as ‘‘low active’’ based on their
responses to the Godin-Leisure Time Questionnaire (18) with-
out the use of objective assessment (e.g., accelerometers).
Nevertheless, the Godin-Leisure Time Questionnaire has pre-
viously been shown to be significantly related to objective
measures (e.g., CalTrac accelerometer) of physical activity (r=
0.45, PG0.01) assessed during a 1-wk period (39). Further-
more, mean values of W
were 82% of the age-, sex-, and
height-predicted normal values (n= 39), thus supporting our
participants_self-report of being low active.
Music is widely used by exercisers for its real and/or
perceived psychological benefits (e.g., affect, motivation). It
follows that our use of music during preintervention and
postintervention CWR exercise tests increased the ecologi-
cal validity of our study and its findings. The generaliz-
ability of our findings may be limited to apparently healthy,
young, and low-active women. Furthermore, our interven-
tion was acute (single-session) and we cannot comment on
the potential benefits of repeated ACT interventions on
measures of high-intensity exercise performance. Thus, fu-
ture research should examine the potential performance-
enhancing effects of short- and long-term ACT interventions
in various other healthy (e.g., elderly, endurance-trained
athletes) and clinical samples of men and women. Moreover,
future research needs to establish whether it was the accep-
tance, cognitive defusion, or a combination of both ACT
techniques that was the active ingredient in the reduction in
perception of effort found in the present study.
In summary, the novel results from this randomized con-
trolled study suggest that psychological techniques derived
from ACT can be used in combination with music to help
low-active women to perform high-intensity exercise for lon-
ger while also feeling less perceived effort and experiencing
more enjoyment. Ultimately, the observed reduction in per-
ception of effort and behavioral benefits derived from the
ACT intervention, if sustained, may be associated with im-
proved physical activity adoption and adherence with atten-
dant health benefits. In this regard, the theoretically grounded
findings of our study provide a rationale for further investi-
gation of short- and long-term ACT interventions to enhance
the established health benefits of high-intensity exercise train-
ing in both health and disease.
E.I. was supported by the Coca-Cola Company Doctoral Student
Grant on Behavior Research Fund from the American College of
Sports Medicine Foundation, by the Fonds de la Recherche en sante
du Que´ bec (FRSQ) doctoral research fellowship, and by the Canadian
Psychological Association Foundation Student Research Grant Awards.
D.J. was supported by a Chercheurs-Boursier Junior 1 salary award
from the FRSQ and by a William Dawson Research Scholars Award
(McGill University). The authors would like to thank Daniel Kopala-
Sibley for his thoughtful comments and statistical advice; Sabrina
Cesare, Monique du Boulay, Diane Moliva, Liseanne Nelson, and Regina
Yung for their assistance with data collection; and all the women who
volunteered their time and efforts to participate in this study. The au-
thors thank the anonymous reviewers for their comments that helped
to strengthen the article.
The authors declare that there are no conflicts of interest.
The findings from the present study do not constitute endorse-
ment by the American College of Sports Medicine.
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