Psychology of Sport and Exercise 28 (2017) 1e10

Contents lists available at ScienceDirect

Psychology of Sport and Exercise
journal homepage: www.elsevier.com/locate/psychsport

More efﬁcient, perhaps, but at what price? Pleasure and enjoyment
responses to high-intensity interval exercise in low-active womenwith obesity
Emily S. Decker a, Panteleimon Ekkekakis b, *abDivision of Renal Diseases and Hypertension, University of Colorado Denver, United States
Department of Kinesiology, Iowa State University, 237 Forker Building, Ames, IA 50011, United Statesa r t i c l e i n f o

a b s t r a c t

Article history:
Received 26 May 2016
Received in revised form
22 August 2016
Accepted 14 September 2016
Available online 14 September 2016

Objectives: Fewer than 1.5% of women with obesity in the USA are physically active at recommended
levels. High-intensity interval exercise (HIIE) has been proposed as a possible solution to the problem of
low activity, based on the dual promise of accelerating the accrual of beneﬁts while reducing the timecommitment. However, concerns have been raised about the appeal and sustainability of HIIE. The
purpose of this study was to compare during-exercise affective valence and post-exercise enjoyment inresponse to a bout of HIIE and a longer, isocaloric bout of moderate-intensity continuous exercise (MICE).
Design: Within-subjects experiment.
Methods: Low-active women with obesity (N ¼ 24) completed one bout of HIIE (3-min warm-up, four 3min intervals of recumbent cycling at 115% of Watts at the ventilatory threshold, four 2-min periods ofactive recovery at 85% of Watts at the ventilatory threshold, 5-min cool-down) and one bout of MICE (3min warm-up, 25 min of recumbent cycling at 90% of Watts at the ventilatory threshold, 5-min cooldown) in counterbalanced order. The Feeling Scale (FS) was administered during exercise and the
Physical Activity Enjoyment Scale (PACES) was administered after cool-down.
Results: Differences were found for both FS (condition by time interaction: p < 0.001, h2 ¼ 0.27) and
PACES (p ¼ 0.04, d ¼ 0.38), with both outcomes favoring MICE.
Conclusions: The lower pleasure and enjoyment associated with HIIE compared to MICE underscore theimportance of considering not only physiological adaptations but also the appeal and sustainability of
HIIE for low-active women with obesity.
© 2016 Elsevier Ltd. All rights reserved.

Keywords:
Aerobic interval training
Affective valence
Enjoyment
Tolerability
Adherence

Compliance with physical activity recommendations among
American adults remains low, posing a challenge to public-healthresearchers and practitioners. Objective assessments of physicalactivity with accelerometry from the National Health and Nutrition
Examination Survey (N ¼ 3522) show that only 3.2% of American
adults accumulate at least 30 min of moderate-intensity physicalactivity, in bouts of at least 10 min, on at least 5 days per week
(Tudor-Locke, Brashear, Johnson, & Katzmarzyk, 2010). Importantly, noncompliance varies by both sex and body-mass-index(BMI) category. Women with obesity, a segment of the population
now estimated to comprise 36% of adult women (Flegal, Carroll, Kit,
& Ogden, 2012) and projected to comprise 45e52% by 2030 (Wang,
McPherson, Marsh, Gortmaker, & Brown, 2011), exhibit the lowest* Corresponding author.
E-mail address: ekkekaki@iastate.edu (P. Ekkekakis).
http://dx.doi.org/10.1016/j.psychsport.2016.09.005
1469-0292/© 2016 Elsevier Ltd. All rights reserved.

levels of physical activity. Speciﬁcally, fewer than 1.5% of womenwith obesity do the minimum amount of physical activity recommended for health promotion (Tudor-Locke et al., 2010). On
average, women with obesity are estimated to perform only
13.8 min of moderate- and 10.8 s of vigorous-intensity physicalactivity daily (Archer et al., 2013).
The aetiology of this extremely low level of physical activity is
unknown and there is presently no evidence base to support
practice guidelines for addressing the problem (Ekkekakis, Vazou,
Bixby, & Georgiadis, 2016). The dearth of information is reﬂectedin position statements by American (Donnelly et al., 2009) andEuropean (Fogelholm, Stallknecht, & Van Baak, 2006) organizations, which detail how much physical activity adults with obesity
should be doing and why but contain no guidance on methods ofpromotion and implementation that can encourage sustained
participation.

2

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

1. Approaches to exercise prescription: tortoise versus hare
Two fundamentally different approaches to exercise prescription have evolved in practice. The traditional approach calls formoderate-intensity continuous exercise (MICE) of prolonged
duration. The preference for MICE is based on three main arguments (Smart & Ismail, 2013): (a) it provides an adequate stimulus
for clinically meaningful adaptations in cardiometabolic parameters, (b) it entails low risk of injury and other adverse events, and (c)it is presumed to be tolerable for most individuals. Thus, thisapproach is presently advocated by most scientiﬁc bodies. For
example, the American College of Sports Medicine (2014) recommends that, for adults with obesity, the intensity should be set
initially at 40e60% of oxygen uptake or heart rate reserve and theduration at 30 min, with progression to intensities over 60% andduration of 60 min, as long as participants are “capable and willing”(p. 320).
On the other hand, two characteristics of MICE may contributeto the low participation among adults with obesity. First, critics
have noted that “moderate activity provides little metabolic stressand, as a result, confers little improvement in aerobic ﬁtness andminimal weight loss,” thus causing frustration and making dropout“a rational decision” (O'Donovan & Shave, 2007, p. 434). Second,since, like most adults, adults with obesity cite “lack of time” as theprimary reason for their low activity (e.g., Andersen & Jakicic,2009), authors have noted that recommendations requiring aminimum daily investment of 30e60 min are “totally unrealistic
and largely unattainable for the majority of the populace” (Bird &Hawley, 2012, p. 314).
The alternative approach, namely high-intensity interval exercise (HIIE), was originally developed as a training method for athletes but has been proposed as appropriate for public health in thelast decade (e.g., Gaesser & Angadi, 2011; Gibala & McGee, 2008;
Gillen & Gibala, 2014; Rehn, Winett, Wisløff, & Rognmo, 2013).
This suggestion has had a profound impact on the research literature and exercise programs on a global scale, presumably becauseof the promise of addressing the two aforementioned limitations ofMICE (i.e., accelerating the accrual of beneﬁts while reducing thetime commitment). Thus, in recent years, HIIE has been proposed as
an appropriate intervention speciﬁcally for individuals with obesity(Boutcher, 2011), diabetes (Bird & Hawley, 2012), and the metabolic
syndrome (Kessler, Sisson, & Short, 2012). Proponents argue that,by providing a stronger stimulus to the cardiorespiratory system,
HIIE may accelerate gains in aerobic capacity compared to MICE
(Elliott, Rajopadhyaya, Bentley, Beltrame, & Aromataris, 2015;
Milanovic, Sporis, & Weston, 2015; Weston, Wisløff, & Coombes,2014). Moreover, HIIE may yield beneﬁts similar to MICE for arange of cardiometabolic parameters, as well as reductions in bodymass and waist circumference, but with a shorter time commitment (Hwang, Wu, & Chou, 2011).

Importantly, these arguments are based on the belief that, besides its cardiometabolic beneﬁts, HIIE “remains popular in thegeneral public” (Jung et al., 2016, p. 2) and is “very enjoyable”(Kilpatrick, Jung, & Little, 2014, p. 14). Authors claim that, comparedto MICE, participants report “highest enjoyment” when engaged in
HIIE (Kilpatrick et al., 2014, p. 14). Reportedly, this is due to “adecreased subjective feeling of fatigue, breathlessness, andmonotony” (Juneau et al., 2014, p. S403). Researchers who sharethese views have suggested that, due to the intermittent nature of
HIIE, the well-characterized negative relationship between exercise
intensity and affective responses (Ekkekakis, Parﬁtt, & Petruzzello,2011) may not apply in the case of HIIT (Jung et al., 2016).
On the opposite side of the debate, skeptics have pointed outthat the evidence in support of HIIE is still evolving. Citing limited
evidence on efﬁcacy and safety, the American Heart Association has
determined that, for patients with cardiovascular disease, HIIE“cannot yet be broadly recommended” (Fletcher et al., 2013, p. 915).
Similarly, other experts have concluded that, for patients with heart
failure, “there is currently insufﬁcient evidence to supplant acontinuous [MICE] approach with this new [exercise training]model” (Arena, Myers, Forman, Lavie, & Guazzi, 2013, p. 104).
Indeed, randomized trials of patients with coronary artery disease
and heart failure found no evidence of superiority of HIIE over MICE
in cardiovascular outcomes, including maximal aerobic capacity(Conraads et al., 2015; Støylen et al., 2012).
Skeptics have also expressed concerns about HIIE possibly
raising the risk of injury, discomfort, nonadherence, and dropout(e.g., De Feo, 2013; Keteyian, 2012). Speciﬁcally, HIIE has beenfound to be associated with a higher rate of adverse events during
exercise or within the 24 h postexercise in patients with cardiometabolic diseases, leading reviewers to warn that “caution
must be taken” (Levinger et al., 2015, p. 62). Other authors haveemphasized that, in considering the beneﬁt-to-risk ratio of highexercise intensity, the effects on parameters beyond the cardiovascular system, such as the health of the brain, should not be
overlooked. It is still unknown, for example, how elevated stresshormone levels (e.g., cortisol), changes in electrolyte balance,
inﬂammation, hypoxia, and oxidative stress associated with highintensity exercise may inﬂuence brain structure and function(Tarumi & Zhang, 2015). Lucas, Cotter, Brassard, and Bailey (2015)
have also warned that “the potential dangers of [HIIE] to thebrain are not trivial,” in part due to increasing “the risk of hyperperfusion injury predisposing to stroke or blood-brain barrier
breakthrough” (p. 905). Finally, while most available randomized
trials are underpowered to investigate differences in adherence, in
one trial with inactive overweight and obese adults in a community
setting, the researchers attributed the minimal effect of HIIE on
aerobic capacity to the higher participant attrition, lower session
attendance, and lower percentage of prescribed exercise completed
among HIIE participants than those assigned to MICE (Lunt et al.,2014).

2. The great intensity debate
The HIIE-vs-MICE debate has become polarized and heated,with strong opinions being expressed from both sides (Biddle &Batterham, 2015; Del Vecchio, Gentil, Coswig, & Fukuda, 2015;
Hardcastle, Ray, Beale, & Hagger, 2014; Holloway & Spriet, 2015;
Jung, Little, & Batterham, 2016; Wisløff, Coombes, & Rognmo,2015). Proponents of HIIT are “convinced that HIIT is superior to
MICE” (Juneau, Hayami, Gayda, Lacroix, & Nigam, 2014, p. S403)
and “believe that the time to introduce high-intensity exercise to
the whole community has come” (Rehn et al., 2013, p. 5). Thus, theyassert that “HIIT should play a central role in health activity
guidelines to maximize the beneﬁts of physical activity globally”(Wisløff et al., 2015, p. 5216).

3. The appeal of HIIE remains undetermined: methodologicalchallenges
The appeal of HIIE in different populations remains an open
empirical question (Jung et al., 2016). Over a decade ago, Coyle(2005) wrote that “a feeling of severe fatigue” is “the 'price' for[the] effectiveness and remarkable time efﬁciency” of HIIE (p.
1983). Since then, research has focused on two constructs of central
importance to how exercise is experienced, namely (a) affective
valence (i.e., pleasure versus displeasure), typically rated on asingle-item scale during exercise, and (b) enjoyment, typicallymeasured with a multi-item questionnaire after exercise. Both affective valence (Ekkekakis & Dafermos, 2012; Rhodes & Kates,

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e102015) and enjoyment (Rhodes, Fiala, & Conner, 2009) have beenfound to be associated with physical activity.
Investigations of affect and enjoyment in response to HIIE sessions among healthy adults have been contradictory. Some authors
claim that HIIE “may be a viable alternative to continuous
moderate-intensity exercise prescriptions” (Jung, Bourne, & Little,
2014, p. 16). Others have concluded that HIIE “leads to signiﬁcant
increase in negative emotions both during and after the exercise in
sedentary subjects,” which may in turn “hinder the adherence tophysical activity” (Saanijoki et al., 2015, p. 2610).
The apparent inconsistency of experimental results may be due
to several methodological differences. First, there is a risk ofparticipant self-selection bias, with most studies having been
conducted with young, healthy, active, and ﬁt college students,
many enrolled in exercise-science programs. Results based on such
samples arguably have limited generalizability to the general adult
population, which is characterized by high body mass and low
activity. For example, in a study cited nearly 100 times, the authors
reported that a bout of HIIE resulted in higher enjoyment scoresthan a bout of MICE, a ﬁnding that was discussed as potentially“relevant for improving exercise adherence” (Bartlett et al., 2011, p.
547). However, the eight young male participants (mean age 25 ± 5years), despite being described as “recreationally active,” had amaximal aerobic capacity above the 95th percentile for their age(57 ml,kg1,min1). On the other hand, the 28 sedentary men(mean age 47 ± 5 years) studied by Saanijoki et al. (2015) had amaximal aerobic capacity at the 20th percentile for their age on
average (34 ml,kg1,min1). In another study, the men had an
average aerobic capacity at the 65th percentile (45 ml,kg1,min1)
but the women at the 15th percentile (28 ml,kg1,min1) and yet
no analyses by gender were reported (Jung et al., 2014).
A second possible contributor to the inconsistency in the results
reported thus far is the choice of intensities characterized as “highintensity” in HIIE bouts and as “moderate intensity” in MICE bouts.
Intensities are commonly selected without reference to a guiding
physiological framework, thus occasionally resulting in misleading
conclusions. For example, in one study, because physiological drift
and the slow component of oxygen uptake (Jones et al., 2011) were
not taken into account, a condition described as “moderate-intensity” continuous exercise was, in fact, performed at consistently
higher heart rate than a comparator condition described as “heavyintensity” interval exercise (Kilpatrick, Greeley, & Collins, 2015).
Likewise, a condition described as “heavy-intensity” continuous
exercise was, in fact, performed at higher heart rate than acomparator condition described as “severe-intensity” interval exercise. Since conditions described as being of lower intensity wereconsistently of higher intensity and vice versa, any conclusions
framing the study as a comparison between HIIE and MICE must bequestioned.
Problems are also evident in studies cited as supporting theconclusion that HIIE is experienced as less pleasant than MICE. For
example, in one such study, each 2-min high-intensity interval
consisted of exercise at 100% of peak oxygen uptake, while recovery
periods lasted for only 57 ± 10 s (Oliveira, Slama, Deslandes,
Furtado, & Santos, 2013). However, it is well established that exercise in the “severe” range of intensity (i.e., from the level ofcritical power to peak oxygen uptake) can only be sustained for a
few minutes and this range of tolerance is further shortened withrepeated bouts and short recovery periods (Bailey, Vanhatalo,
Wilkerson, DiMenna, & Jones, 2009; Coats et al., 2003; Ferguson
et al., 2007). The diminished tolerance in such protocols is presumed to be due to the depletion of high-energy phosphate andglycogen stores in muscles, as well as the incomplete removal of
metabolites and restoration of pH levels (Jones, Vanhatalo, Burnley,
Morton, & Poole, 2010). Thus, despite the fact that the (male)3

participants in the study by Oliveira et al. (2013) were young (24 ± 4years) and ﬁt (48 ± 7 ml,kg1,min1, 75th percentile), it is perhaps
unsurprising that more than half (8 of 15) could not complete the
HIIE condition.
A third issue that has likely contributed to the inconsistency inprevious results is the relative duration of the HIIE and MICE sessions. HIIE sessions have been compared to MICE sessions that wereas short as 20 min (Kilpatrick et al., 2015; Martinez, Kilpatrick,
Salomon, Jung, & Little, 2015) or as long as 40 min (Jung et al.,2014; Saanijoki et al., 2015) or even 50 min (Bartlett et al., 2011).
Moreover, since the main argument supporting the promotion of
HIIE in the domain of public health is its time efﬁciency (e.g., Bird &Hawley, 2012; Gibala & McGee, 2008; Gillen & Gibala, 2014), one
would expect HIIE sessions to be compared to MICE sessions thatare longer. However, some studies have compared HIIE and MICE
sessions of equal duration (e.g., Kilpatrick et al., 2015) or even HIIE
sessions that were longer than MICE (Martinez et al., 2015).
A fourth potential contributor to the inconsistencies in previous
results is the method of affect assessments. Previous research has
established that ratings of pleasure-displeasure track changes in
exercise intensity closely, reliably worsen over time when the intensity exceeds the ventilatory threshold, and exhibit a robust
positive rebound when the exercise stops or the intensity is
reduced (Ekkekakis et al., 2011). Therefore, for the assessment
protocol to faithfully represent the presumably dynamic changes inpleasure-displeasure during a bout of HIIE, ratings must be obtained from participants at least at the highest point of the “peaks”(i.e., at the end of recovery periods) and the lowest point of the“valleys” (i.e., at the end of the high-intensity intervals). However,in some studies, ratings were obtained at the midpoint of the interval and recovery periods (Jung et al., 2014), thus missing thepeaks and valleys and misrepresenting the shape of the affective
response. In other studies, ratings were obtained only after thehigh-intensity intervals, thus capturing the affective response to
the cessation of intense exercise rather than the response to thehigh-intensity intervals themselves (Oliveira et al., 2013; Saanijoki
et al., 2015). Finally, in studies in which ratings were obtained“during the last 15 s” (Kilpatrick et al., 2015, p. 247) or “during thelast 10 s” (Martinez et al., 2015, p. 141) of the high-intensity intervals, the bipolar rating scale of pleasure-displeasure was presented side-by-side with a unipolar scale of enjoyment, asking
respondents to “indicate how much you are enjoying this exercise
session.” This juxtaposition, and the associated variance transfer,
may have introduced a biasing effect on ratings of pleasuredispleasure. In particular, the phrase “how much you are enjoying” (a typical example of a “loaded” or “leading” question) and the
instruction to rate the degree of enjoyment without permitting
respondents to indicate any degree of aversion may have negatively
impacted the validity of pleasure-displeasure assessments during
exercise.
Thus far, the affective and enjoyment responses to HIIE andMICE among low-active adults with obesity or other cardiometabolic risk factors have not been compared in a study speciﬁcally designed and powered for this purpose. In a study of only 8
patients with type 2 diabetes (mean age 63 years, mean BMI
32 kg,m2), the anticipated enjoyment of future HIIE sessions was
rated highly (~8 out of 9, with 9 being “very enjoyable”) but there
was no comparison to MICE (Little et al., 2011). A study of 19 young,sedentary, overweight or obese men (mean age 23 years, mean BMI
31 kg,m2), whose maximal aerobic capacity (35 ml,kg1,min1)
was “poor” (bottom 20% for their age), showed that repeated 1-min
intervals at 100% of maximal capacity yielded nearly ﬁvefold larger
declines in pleasure (6.9 versus 1.4-point drop on an 11-point scale)than intervals at 70% (Boyd, Simpson, Jung, & Gurd, 2013). On theother hand, there was no difference in anticipated enjoyment

4

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10(“How enjoyable would it be for you to do high-intensity interval
training 3 days per week?”), with both groups averaging more than
6 out of 7 (with 7 being “extremely enjoyable”). Finally, in a study of
10 overweight or obese adults (8 women), with mean age of 41
years, mean BMI of 36 kg,m2, and estimated maximal aerobic
capacity of 22 ml,kg1,min1 (i.e., “very poor”), the authors
concluded that “there were no signiﬁcant differences” (p. 838) for
either during-exercise affective valence or post-exercise enjoyment
between HIIE and MICE conditions (Little, Jung, Wright, Wright, &Manders, 2014). The lack of a statistically signiﬁcant difference,
however, was likely due to the low statistical power afforded by thesmall sample, since there was a medium-size difference in theratings of during-exercise valence (d ¼ 0.56) and a small-tomedium difference in post-exercise enjoyment (d ¼ 0.28), both infavor of MICE.
4. The present study
While there is no universal deﬁnition of HIIE, the core feature of
HIIE is the alternation between (a) intervals of “‘all-out’ effort” or an
intensity “close to that which elicits VO2peak (i.e., >90% of VO2peak),”lasting “from a few seconds to up to several minutes” and (b) periods of passive or active recovery (“rest or low-intensity exercise”)
lasting “up to a few minutes” (Gibala & McGee, 2008, p. 58). To
appropriately calibrate the intensity and the volume of HIIE bouts
for different populations, it has been suggested that “future studies
should examine modiﬁed interval-based approaches” (Gibala &McGee, 2008, p. 62). This call has led to the emergence of two
broad categories of HIIE (Kessler et al., 2012): (a) “sprint interval
training” (SIT) typically involves 4e6 cycles of 30-s bursts at “allout” (i.e., maximal or supramaximal) intensity, whereas (b) “aerobic interval training” (AIT) typically involves 4e6 cycles of exercise
at 80e95% of maximal capacity, each lasting for 3e4 min. Becauseof reports of nausea and light-headedness during sessions of SIT(e.g., Richards et al., 2010), the present study focused on AIT.
Thus, the purpose of the present study was to compare the effects of a session of HIIE/AIT and a session of MICE on duringexercise affective valence and post-exercise enjoyment in lowactive women with obesity. Previous research has shown thatwomen with obesity report lower levels of pleasure across theentire range of exercise intensity than their non-obese counterparts(Ekkekakis, Lind, & Vazou, 2010) and the difference may growlarger at higher intensities (da Silva et al., 2011). Thus, when asked
to choose between higher intensity or longer duration, more
women with obesity choose lower intensity, even if this means
exercising for a longer period of time (Fogelholm, KukkonenHarjula, Nenonen, & Pasanen, 2000). On the other hand, according to anecdotal accounts from a study of patients with the metabolic syndrome (mean age 55 years, mean BMI 30 kg,m2),
participants “found it motivating to have a varied procedure tofollow” whereas participants in a moderate-intensity walking
condition “found it 'quite boring' to walk continuously during thewhole exercise period” (Tjønna et al., 2008, p. 352). Intermittent
activity is also perceived as more rewarding or enjoyable thancontinuous activity by non-obese children (Barkley, Epstein, &Roemmich, 2009) and ﬁt young adults (e.g., Bartlett et al., 2011).
Thus, given the contradictory prior evidence, no directional hypothesis regarding the affective and enjoyment responses to asession of HIIE/AIT and a session of MICE could be formulated.
5. Methods
5.1. Participants
An initial power analysis assuming an effect size of d ¼ 0.6 for acomparison between two dependent means on the primary
outcome, namely ratings of affective valence (pleasure-displeasure)during exercise (Ekkekakis et al., 2010), and alpha of 0.05, indicatedthat 24 participants were required to reach 80% statistical power.
Participants were recruited via (a) invitations e-mailed to all faculty, staff, and students of a large university in the Midwestern
United States and (b) ﬂiers posted throughout the community andcampus, distributed at local super-markets, and inserted into the
local Sunday newspaper.
Our goal was to evaluate the potential of HIIE/AIT as an exercise
intervention among women with obesity exercising in unsupervised settings rather than under medical supervision. Thus, wetargeted recruitment to asymptomatic participants with no morethan two cardiovascular risk factors (i.e., obesity and sedentary
lifestyle) and, therefore, no more than “moderate” risk (ACSM,
2014). Speciﬁcally, the inclusion criteria were (a) age of 18e54
years, (b) obesity (BMI  30 kg,m2), (c) fewer than 30 min ofmoderate-intensity physical activity per day on most days of theweek, based on responses to a 7-day physical activity recall interview, (d) no reported change in physical activity habits over the
past 6 months, (e) a medical examination in the last 12 months thatrevealed no contraindications to vigorous exercise, (f) “apparently
healthy” status determined by negative responses to all questions
on the Physical Activity Readiness Questionnaire (Thomas, Reading,& Shephard, 1992), and (g) no current injuries or ailments. Exclusion criteria were smoking, hypertension, dyslipidemia, impaired
fasting glucose, and use of any medication that could inﬂuencecardiovascular or metabolic responses to exercise, consistent withthe risk stratiﬁcation criteria speciﬁed by ACSM (2014).
Of 488 women who expressed interest, 38 met eligibility
criteria. Of those, 7 did not schedule or attend their ﬁrst session and1 had a change in health status prior to enrollment that prevented
participation. Of the 30 individuals enrolled, 6 dropped out due tothe following reasons: injury unrelated to the study (n ¼ 2);
discomfort from the face mask (n ¼ 2); personal reasons (n ¼ 1);
inability to complete the HIIE/AIT session (n ¼ 1). Thus, 24 women
were included in the analyses (see Table 1 for demographic andanthropometric characteristics).
5.2. Measures
5.2.1. Affective valence
The core affective dimension of affective valence (i.e., pleasuredispleasure) was designated the primary outcome variable. It wasassessed with the Feeling Scale (FS; Hardy & Rejeski, 1989). The FS
Table 1
Descriptive statistics (M ± SD) for demographic, anthropometric, and physiologicalcharacteristics of the participants (N ¼ 24).
M ± SDAge (years)
Age Range (years)
Height (cm)Body Mass (kg)Body Fat (%)
Body Mass Index (kg,m2)
Obesity Class I, II, III (nI, nII, nIII)
Systolic Blood Pressure (mmHg)a
Diastolic Blood Pressure (mmHg)a
Baseline Heart Rate (beats,min1)aVO2peak (L,min1)VO2peak (mL,kg1,min1)
Ventilatory Threshold (L,min1)
Ventilatory Threshold (ml,kg1,min1)
Ventilatory Threshold (%VO2peak)a39.25 ± 11.23
19e53
164.15 ± 7.19
94.20 ± 12.81
44.00 ± 4.27
34.96 ± 4.46
11, 11, 2
127.06 ± 12.77
79.42 ± 9.80
76.21 ± 10.66
1.77 ± 0.31
19.05 ± 3.67
1.08 ± 0.16
11.64 ± 2.12
61.57 ± 6.24

Average of two measurements, prior to the HIIE/AIT and MICE bouts.

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

is an 11-point, single-item, bipolar rating scale commonly used forthe assessment of affective responses during exercise. The scale
ranges from 5 to þ5. Anchors are provided at zero (“Neutral”) andat all odd integers, ranging from “Very Good” (þ5) to “Very Bad”
(5).
5.2.2. Enjoyment
Post-exercise enjoyment was designated a secondary outcome.
It was assessed with the Physical Activity Enjoyment Scale (PACES;
Kendzierski & DeCarlo, 1991). The PACES consists of 18 semanticdifferential items, with the opposites separated by a 7-point scale(e.g., 1: “I enjoy it”; 7: “I hate it”). Respondents are instructed to“rate how [they] feel at the moment about the physical activity[they] have been doing.” Validation studies have shown a negative
correlation with boredom and a signiﬁcant prediction of choice
between different activities (Kendzierski & DeCarlo, 1991). In thepresent study, the internal consistency of the questionnaire washigh (Cronbach's alpha coefﬁcient of 0.98 and 0.97 after MICE and
HIIE/AIT, respectively).
5.2.3. Perceived exertion
The perception of exertion during exercise was another secondary outcome. It was assessed with the extensively validated
Rating of Perceived Exertion (RPE; Borg, 1998), a 15-point scaleranging from 6 (“No exertion at all”) to 20 (“Maximal exertion”).
5.2.4. Descriptive assessments
Additional anthropometric and physiological assessments werecarried out to characterize the sample and provide manipulation
checks. Speciﬁcally, body mass and body composition were
measured with a bioelectrical impedance analyzer with integrated
electronic scale (model BF-626, Tanita, Tokyo, Japan). Stature wasmeasured with a wall-mounted stadiometer. Oxygen uptake (VO2)
was measured with a metabolic cart (model TrueOne 2400, ParvoMedics, Salt Lake City, UT, USA), calibrated before each use.
5.3. Procedures
5.3.1. Experimental design
The study included three sessions of stationary recumbent
cycling, a non-weight-bearing modality appropriate for adults withobesity: (a) an incremental test to volitional termination, todetermine VO2peak and ventilatory threshold (VT), (b) a session of
HIIE/AIT, and (c) an isocaloric session of MICE, the latter two performed in computer-determined random and counterbalanced
order.
5.3.2. Incremental exercise test
The ﬁrst session included a familiarization period, intended tomake participants feel comfortable in the laboratory environmentand give them an opportunity to ask questions. Additionally, allparticipants read and signed an informed consent document,
approved by the Institutional Review Board, in which the purposeof the study was described generically as “investigation of physiological and psychological responses to exercise.” The participants
were then ﬁtted with a nose-and-mouth breathing face mask
(model 8920/30, Hans Rudolph, Kansas City, MO, USA), equippedwith an ultralow-resistance one-way valve (model 2700, Hans
Rudolph). A gel sealant (model 7701, Hans Rudolph) was applied to
the face mask to prevent air leaks. The exercise test was performed
on a recumbent cycle ergometer (Corival Recumbent, Lode BV,
Groningen, Netherlands) equipped with a wide, well-cushioned
seat. Participants began cycling against a workload of 20 W for
3 min, followed by a 10 W,min1 ramp until volitional termination.
The highest 60-s average of VO2 was designated VO2peak.

5

5.3.3. VT determination
Gas exchange data were analyzed ofﬂine to determine the VT,
using the three-method procedure proposed by Gaskill et al. (2001)
and computerized by Ekkekakis, Lind, Hall, and Petruzzello (2008).
The three methods included (a) the V-slope, based on a change inslope in the relationship between VCO2 and VO2, (b) the method ofventilatory equivalents, based on a rise in VE/VO2 without a concurrent rise in VE/VCO2, and (c) the method of excess CO2, based on
an increase in excess CO2 from steady state. All data were converted
to 20-s averages before analysis to reduce noise. Three experienced
investigators analyzed the data independently. Determination of
the VT required agreement between at least two of the three.
5.3.4. Workload determination
Energy expenditure is a central consideration in exercise interventions for adults with obesity. Although it has been suggested
that the higher intensity of HIIE should raise excess post-exercise
oxygen consumption and, thus, result in total 24-h energy expenditure (TEE) matching that associated with MICE, the increase in
TEE resulting from bouts of HIIE may be small (e.g., ~10%, Sevits
et al., 2013). Consequently, it remains unclear whether HIIE canraise TEE to the same extent as MICE (Hazell, Olver, Hamilton, &Lemon, 2012; Kelly, King, Goerlach, & Nimmo, 2013; Skelly et al.,2014). Thus, given the focus of the present study on obesity, thebouts of HIIE/AIT and MICE were designed to be isocaloric,
consistent with other studies of participants with obesity and themetabolic syndrome (Martins et al., 2016; Tjønna et al., 2008).
Equating caloric expenditure was accomplished with extensive
pilot-testing, taking into account several competing considerations
and addressing the methodological issues identiﬁed in the introduction. Speciﬁcally: (a) the session of MICE had to last ~30 min (asper physical activity recommendations; Haskell et al., 2007) and be
performed at an intensity that would allow the low-active participants to complete the session without stopping, (b) the highintensity intervals had to reach intensities consistent with HIIT(~90% VO2peak), (c) the duration of the high-intensity intervals had
to be tolerable for four repetitions, (d) the intensity of the HIIE
active-recovery periods had to be low enough to allow participants
sufﬁcient recovery before the next high-intensity interval and, atthe same time, high enough to make a substantial contribution tothe overall energy expenditure of the session, and (e) the HIIT
session had to be shorter than MICE.
Based on evidence on the relation between exercise intensityand pleasure-displeasure, the intensities were set in relation to the
VT (Ekkekakis et al., 2011). Speciﬁcally, the session of MICE consisted of (a) 3-min warm-up (20 Watts), (b) 25 min of cycling at 90%of the Watts corresponding to the VT (to attenuate the slow
component of VO2 and reduce drift), and (c) 5-min cool-down (20Watts). The session of HIIT consisted of (a) 3-min warm-up (20Watts), (b) alternation between four 3-min intervals of cycling at
115% of the Watts corresponding to the VT and four 2-min periodsof active recovery at 85% of the Watts corresponding to the VT (totalof 20 min), and (c) 5-min cool-down (20 Watts).
5.3.5. Outcome assessment protocol
The self-report rating scales were kept out of the ﬁeld of vision
during exercise and were presented (on laminated posters) only at
predetermined intervals. Participants indicated their choices bypointing to a number and the researcher conﬁrmed their choices byreading the number in a neutral tone of voice. During the HIIE/AIT
bout, the FS and RPE were administered (in random order, to prevent systematic variance transfer) during the last 15 s of each highintensity and active-recovery period (a total of 8 times, at min 2:00,
5:00, 7:00, 10:00, 12:00, 15:00, 17:00, 20:00). During the MICE bout,
the FS and RPE were administered (also in randomized order) in the6

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

last 15 s of each 2:30-min period (a total of 10 times, at min 2:30,
5:00, 7:30, 10:00, 12:30, 15:00, 17:30, 20:00, 22:30, 25:00). In order
to compare responses at equivalent time points despite thedifferent durations of the HIIE/AIT and MICE bouts, the 10 data
points from the MICE bout were divided in two sets of 5 and asecond-degree polynomial regression was ﬁtted to each segment(for each participant). The regression parameters were then used toestimate the FS and RPE values at the following eight percentages ofbout duration (matching the assessment time points during the
HIIE/AIT bout): 10%, 25%, 35%, 50%, 60%, 75%, 85%, and 100%.
Additionally, the FS was administered immediately prior to each
exercise bout, immediately after the bout, immediately after thecool-down, and 10, 20, and 30 min after exercise. The PACES was
administered immediately after the cool-down in both conditions.
5.3.6. Statistical analyses
Data were analyzed with condition-by-time repeated-measures
analyses of variance (ANOVAs). When the sphericity assumption
was violated, the Greenhouse-Geisser correction was applied to thedegrees of freedom. Signiﬁcant interactions were followed by
Bonferroni-corrected pairwise comparisons.

showed a main effect of Condition, F(1, 23) ¼ 14.42, p < 0.05,
h2 ¼ 0.39, a main effect of Time, F(2.66, 61.11) ¼ 34.92, p < 0.001,
h2 ¼ 0.60, and a Condition by Time interaction, F(3.29,
75.68) ¼ 8.48, p < 0.001, h2 ¼ 0.27. Post-hoc tests showed FS to besigniﬁcantly lower during HIIE/AIT than MICE at the end of eachhigh-intensity interval, 25% (d ¼ 0.78), 50% (d ¼ 0.95), 75%(d ¼ 0.76), and 100% (d ¼ 0.69) of bout duration. FS ratings
declined during the bouts in both conditions but the decrease waslarger during HIIE/AIT (3.46 ± 2.04 units) than MICE (2.25 ± 1.62
units), t (23) ¼ 2.37, p ¼ 0.026. Speciﬁcally, during MICE, thedecrease from baseline was signiﬁcant (p < 0.0014, after Bonferroni
correction) at 60% (d ¼ 0.84), 75% (d ¼ 1.01), 85% (d ¼ 1.18), and100% (d ¼ 1.43), whereas, during HIIE/AIT, the decrease was signiﬁcant at 25% (d ¼ 1.28), 35% (d ¼ 0.92), 50% (d ¼ 1.56), 60%(d ¼ 1.26), 75% (d ¼ 1.61), 85% (d ¼ 1.26), and 100% (d ¼ 1.92). At theﬁnal assessment, FS ratings averaged slightly below zero in the
HIIE/AIT condition (0.04 ± 1.94, where 0 is “neutral” and 1 is“fairly bad”) but were still positive in MICE (1.13 ± 1.34, where 1 is“fairly good”). The conditions did not differ before or after thebouts. These data are illustrated in Fig. 2, panel a.
6.3. Enjoyment

6. Results
6.1. Manipulation check
A comparison of the caloric expenditures of the HIIE/AIT(M ¼ 197 kcal) and MICE (M ¼ 203 kcal) sessions was nonsigniﬁcant, t (23) ¼ 1.33, p ¼ 0.198, d ¼ 0.22. As shown in
Fig. 1, during the HIIE/AIT bout, %VO2peak averaged 90.12% ± 12.96%
during the high-intensity intervals (where  91% VO2max is
considered “near maximal to maximal”; ACSM, 2014, p. 165) and
64.92% ± 11.12% during the periods of active recovery (where 64%
VO2max is the upper boundary of “moderate” intensity). The overall
average was 77.52% ± 11.16%. During the MICE bout, %VO2peak was
66.11% ± 10.04%, with a drift from 61.59% ± 12.05% at 2:30 to
69.57% ± 13.58% at 25:00. During HIIE/AIT, %VO2 at VT averaged
146.21% ± 13.14% during the high-intensity intervals and105.37% ± 14.57% during the periods of active recovery. The overall
average was 125.79% ± 11.73%. During MICE, %VO2 at VT averaged
109.66% ± 19.10%, with a drift from 100.18% ± 17.61% at 2:30 to113.69% ± 23.56% at 25:00.
6.2. Affective valenceA 2 (Conditions) by 9 (Time points: pre, 10%, 25%, 35%, 50%, 60%,
75%, 85%, 100% of bout duration) repeated-measures ANOVA on FS

100%

A paired t-test on PACES scores showed a signiﬁcant difference
between conditions, t (23) ¼ 2.14, p ¼ 0.04, d ¼ 0.38, with higherscores after MICE (90.79 ± 22.60) than after HIIE/AIT(82.25 ± 21.76).
6.4. Perceived exertion
A 2 (Conditions) by 8 (Time points: 10%, 25%, 35%, 50%, 60%, 75%,
85%, 100% of bout duration) repeated-measures ANOVA on RPE
showed a main effect of Condition, F(1, 23) ¼ 6.24, p < 0.001,
h2 ¼ 0.21, a main effect of Time, F(3.32, 76.37) ¼ 71.34, p < 0.001,
h2 ¼ 0.76, and a Condition by Time interaction, F(3.4,
78.05) ¼ 34.25, p < 0.001, h2 ¼ 0.60. Post-hoc tests showed RPE tobe signiﬁcantly higher during MICE at 10% (d ¼ 0.66) and during
HIIE/AIT at the end of each high-intensity interval, namely 25%(d ¼ 1.41), 50% (d ¼ 1.37), 75% (d ¼ 1.17), and 100% (d ¼ 1.40) of boutduration. Compared to 10%, RPE increased signiﬁcantly (p < 0.0018,
after Bonferroni correction) at each time point during MICE, from25% (d ¼ 0.39) to 100% (d ¼ 1.08). While the increases from 10%
during HIIE/AIT across the recovery periods were of similar
magnitude to those observed during MICE, from 35% (d ¼ 0.71) to85% (d ¼ 1.15), the increases during the high-intensity intervals
were much larger, from 25% (d ¼ 2.27) to 100% (d ¼ 3.25). At theﬁnal assessment, the average RPE was 15.21 ± 1.79 in HIIE/AIT
160%

(a)

90%

140%

%VO2 at VT%VO2peak

(b)

150%

80%
70%
60%

130%
120%
110%
100%

HIIE/AIT
MICE

90%
50%

10% 25%35% 50%60% 75%

Bout Duration

85% 100%

80%

10% 25%35% 50%60% 75%85% 100%

Bout Duration

Fig. 1. Percentages of peak oxygen uptake (VO2peak, panel a) and the oxygen uptake corresponding to the ventilatory threshold (VO2 at VT, panel b) achieved during the HIIE/AITand MICE bouts.

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

5.0
4.5

7

(a)

4.0

Feeling Scale (FS)

3.5
3.0
2.5
2.0
1.5
1.0
0.5

HIIE/AIT

0.0

MICE

-0.5

Rating of Perceived Exertion (RPE)

20

(b)

Post-30’

Post-20’

Post-10’

Post-cool-downPost-0’

100%

85%

75%

60%

50%

35%

25%

10%

Pre

-1.0

HIIE/AIT
MICE

18

16

14

12

10

8

6
10%

25%

35%

50%

60%

75%

85%

100%

Bout Duration
Fig. 2. Feeling Scale scores (FS, panel a) and ratings of perceived exertion (RPE, panel b) in response to the HIIE/AIT and MICE bouts. Note: For FS, *p < 0.0055 (for the comparison
between conditions after Bonferroni adjustment). For RPE, *p < 0.00625 (for the comparison between conditions after Bonferroni adjustment); **p < 0.001.

(where 15 is “hard/heavy”) compared to 12.50 ± 2.00 in MICE
(where 11 is “light” and 13 is “somewhat hard”). These data areillustrated in Fig. 2, panel b.
7. Discussion
In the contemporary exercise-science, medical, and publichealth literatures, HIIE is widely described as a promising
approach to exercise prescription that can accelerate the accrual ofﬁtness and health beneﬁts while also circumventing the primary
perceived barrier to exercise participation, namely lack of time.
However, since most exercise-induced adaptations are quickly
reversible following nonadherence or dropout, the success of thismethod in the realm of public health hinges on whether it can beshown to be not only effective and safe but also appealing, tolerable, and sustainable in the long run. In anticipation of pragmatic

trials with adequate post-intervention follow-ups that can evaluate
adherence, research has focused on how the pleasure and enjoyment responses to HIIE compare to those resulting from traditional
MICE. The purpose of the present study was to address this question by focusing on women with obesity, a growing segment of theadult population characterized by alarmingly low levels of physicalactivity.
The results suggest that, in the present sample, and with thespeciﬁc HIIE/AIT and MICE protocols tested in this study, the HIIE/
AIT bout was experienced as signiﬁcantly harder, less pleasant, andless enjoyable than MICE. While the women also reported
increasing levels of perceived exertion and diminishing levels ofpleasure during MICE, the slopes of change over time were steeper
during HIIE/AIT than MICE, leading to signiﬁcant and meaningfulcondition by time interactions in both FS (h2 ¼ 0.27) and RPE(h2 ¼ 0.60).

8

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

The mean FS score during the bout of MICE was 2.00 ± 1.22,
whereas the mean score during HIIE/AIT was 1.25 ± 1.47, resulting
in a 0.75-unit difference and a “medium” effect (d ¼ 0.56). During
HIIE, however, focusing on the average rating may be misleading.
Although the ratings during the periods of active recovery(1.93 ± 1.29) did not differ from those during MICE (d ¼ 0.06),
ratings during the high-intensity intervals (0.57 ± 1.78) showed a
1.43-unit difference or a “large” effect (d ¼ 0.94). Based on evidence
on the association between during-exercise affective valence andphysical activity behavior, these differences are likely consequential. Prospective studies with healthy low-active adults (18e65
years, mean BMI 28 kg,m2) have shown that a 1-unit difference in
FS ratings during exercise can translate to 38e41 min (Williams
et al., 2008) or 15e29 min of additional at-least moderate-intensity physical activity per week (Williams, Dunsiger, Jennings, &Marcus, 2012). While FS scores after the HIIE/AIT and MICE bouts
did not differ, the evidence suggests that post-exercise affective
valence is not signiﬁcantly associated with physical activity(Ekkekakis & Dafermos, 2012; Rhodes & Kates, 2015).
The difference in post-exercise enjoyment approached a “medium” effect (d ¼ 0.38). A meta-analysis of 45 studies using
semantic-differential measures of enjoyment, including the PACES,
yielded an average correlation of r ¼ 0.44 with physical activity
behavior. This approximates a “large” effect size (i.e., r ¼ 0.50),
making enjoyment the strongest known correlate of physical activity (Rhodes et al., 2009).
Although a robust difference in RPE between HIIE/AIT and MICE
was to be expected, it is noteworthy that the difference between
the average RPE during MICE (12.29 ± 2.87) and that during thehigh-intensity intervals of HIIE/AIT (14.32 ± 1.73) was 2.03 units,
representing a “large” effect (d ¼ 0.86). In a previous study ofwomen with obesity who had undergone an exercise weight-loss
intervention, RPE during a bout of walking was associated with
reduced physical activity and increased weight regain one year
after the intervention (each 0.5-unit increase in RPE was associatedwith a 1-kg weight regain; Brock et al., 2010).
A fuller understanding of the possible implications of theobserved differences in affective valence and enjoyment for physical activity behavior requires placing them in the context of previous research on behavioral decision making. Studies on painful
medical procedures and other unpleasant stimuli has demonstrated that the retrospective evaluation of such episodes does not
reﬂect either the total or the average level of pleasure-displeasureexperienced during the episodes. Instead, research has shown
that, while the duration of the episode appears to be of minimal
importance (Fredrickson & Kahneman, 1993), three features of theaffective experience are most consequential: (a) the magnitude ofthe (positive or negative) affective peak(s), (b) the slope (rate ofchange) of affect during the episode, and (c) the affect at the end of
the episode (Ariely, 1998; Ariely & Carmon, 2000; Ariely &Zauberman, 2003; Redelmeier & Kahneman, 1996). Assumingthat post-exercise enjoyment represents a global evaluation of thepreceding bout, it is noteworthy that the difference in PACES scores
between HIIE/AIT and MICE were signiﬁcantly correlated with thedifference in negative peaks in FS ratings (r ¼ 0.50, p ¼ 0.013), thedifference in FS slopes (r ¼ 0.58, p ¼ 0.003), the difference in FS
ratings just before the end of the bouts (r ¼ 0.46, p ¼ 0.025), and thedifference in FS ratings immediately after the bouts (r ¼ 0.59,
p ¼ 0.002). In each of these important features of the affective
experience of exercise, the HIIE/AIT bout yielded more negative
results than the MICE bout, namely a larger negative peak
(3.63 ± 2.03 vs 2.54 ± 1.50, t ¼ 2.85, p ¼ 0.009, d ¼ 0.61), a steeper
negative slope over time (0.14 ± 0.10 vs 0.07 ± 0.06, t ¼ 3.18,
p ¼ 0.004, d ¼ 0.82), lower FS ratings just before the end of thebout (0.04 ± 1.94 vs 1.13 ± 1.33, t ¼ 3.04, p ¼ 0.006, d ¼ 0.70), andlower FS ratings immediately after the bout (0.71 ± 2.12 vs 1.96 ±
1.76, t ¼ 2.90, p ¼ 0.008, d ¼ 0.64).
The challenge of offering adults with obesity exercise experiences that are pleasant (or at least not unpleasant) has been discussed in the literature (Ekkekakis et al., 2016, 2010; Mattsson,€ssner, 1997). Consistent with previous studies ofLarsson, & Ro
women with obesity (Ekkekakis et al., 2010; Hulens, Vansant,Lysens, Claessens, & Muls, 2001), the peak aerobic capacity of theparticipants in the present sample, expressed relative to their bodymass, was “very poor” compared to age-group norms (i.e., bottom
5%; American College of Sports Medicine, 2014). Just as importantly,
their VT occurred, on average, at less than 3.5 metabolic equivalent
units (METs). To put this ﬁgure in perspective, examples of activities
corresponding to 3.5 METs and, therefore, exceeding the average VTof the women in this sample, include such casual everyday activities as walking at 2.8e3.2 miles per hour on a level, ﬁrm surface
without carrying extra weight, washing the car, cleaning windows,
preparing food, using a leaf blower, picking fruit off trees, andﬁshing from a standing position. These examples illustrate thechallenge faced by exercise professionals, and adults with obesity
themselves, in ﬁnding exercise or physical activity opportunities
likely to yield pleasant (or at least non-unpleasant) experiences.
Moreover, the present data show that, while the workload for the
MICE bout was set below (90%) the Watts corresponding to VT, theparticipants could not maintain %VO2-at-VT steady, resulting in adrift to 113.69% within 25 min. Thus, while the bout started withinthe “moderate” range of intensity (61.59% VO2peak), it ended at thelow end of the “vigorous” range (69.57% VO2peak) in terms of VO2,
though not in terms of RPE (12.50). Given the sensitivity ofpleasure-displeasure ratings to intensities exceeding the VT(Ekkekakis et al., 2011), the gradual decline of FS scores during
MICE (up to 2.25 units from baseline) is cause for concern but inline with previous evidence (da Silva et al., 2011; Ekkekakis et al.,2010).
In evaluating the data reported herein, readers must take into
account the limitations of the study. Neither the sample of participants nor the methods described here can be considered representative of all “women with obesity” or “HIIE” in general. The
participants represent a select sample of adult women who, despite
their obesity and low activity levels, were free of chronic diseases
and medication. Women with obesity encountered in clinicalpractice may have more than two risk factors and, thus, may exhibit
even less tolerance to both HIIE and MICE. Likewise, given theabundance of possible HIIE protocols, the protocol used in thepresent study should be considered as only one of a multitude ofpossible options. Other combinations of intervals and recovery
periods may yield different results. In particular, if keeping energy
expenditure equal to MICE is not required, so-called “low-volume”
HIIE, with shorter high-intensity intervals and longer and/or lowerintensity recovery periods, warrants attention. Future studies
should also expand the scope of the present investigation to samples of men, adults with different health and ﬁtness proﬁles, and,
importantly, intervention programs with long-term monitoring ofadherence and dropout patterns.
In conclusion, in a sample of low-active women with obesity, about of HIIE/AIT was rated as less pleasant and less enjoyable thanan isocaloric bout of MICE. These results underscore the importanceof considering the appeal and sustainability of high-intensity
exercise.

References
American College of Sports Medicine. (2014). ACSM's guidelines for exercise testingand prescription (9th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.
Andersen, R. E., & Jakicic, J. M. (2009). Interpreting the physical activity guidelines

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10
for health and weight management. Journal of Physical Activity and Health, 6,
651e656.
bert, J. R., Lau, E. Y., Wang, X., Shook, R. P., et al. (2013).
Archer, E., Hand, G. A., He
Validation of a novel protocol for calculating estimated energy requirements
and average daily physical activity ratio for the US population: 2005-2006.
Mayo Clinic Proceedings, 88, 1398e1407.
Arena, R., Myers, J., Forman, D. E., Lavie, C. J., & Guazzi, M. (2013). Should highintensity-aerobic interval training become the clinical standard in heart failure? Heart Failure Reviews, 18, 95e105.
Ariely, D. (1998). Combining experiences over time: The effects of duration, intensity changes and on-line measurements on retrospective pain evaluations.
Journal of Behavioral Decision Making, 11, 19e45.
Ariely, D., & Carmon, Z. (2000). Gestalt characteristics of experiences: The deﬁning
features of summarized events. Journal of Behavioral Decision Making, 13,191e201.
Ariely, D., & Zauberman, G. (2003). Differential partitioning of extended experiences. Organizational Behavior and Human Decision Processes, 91, 128e139.
Bailey, S. J., Vanhatalo, A., Wilkerson, D. P., DiMenna, F. J., & Jones, A. M. (2009).
Optimizing the “priming” effect: Inﬂuence of prior exercise intensity and recovery duration on O2 uptake kinetics and severe-intensity exercise tolerance.
Journal of Applied Physiology, 107, 1743e1756.
Barkley, J. E., Epstein, L. H., & Roemmich, J. N. (2009). Reinforcing value of intervaland continuous physical activity in children. Physiology and Behavior, 98, 31e36.
Bartlett, J. D., Close, G. L., MacLaren, D. P., Gregson, W., Drust, B., & Morton, J. P.
(2011). High-intensity interval running is perceived to be more enjoyable thanmoderate-intensity continuous exercise: Implications for exercise adherence.
Journal of Sports Sciences, 29, 547e553.
Biddle, S. J. H., & Batterham, A. M. (2015). High-intensity interval exercise training
for public health: A big HIT or shall we HIT it on the head? International Journalof Behavioral Nutrition and Physical Activity, 12, 95.
Bird, S. R., & Hawley, J. A. (2012). Exercise and type 2 diabetes: New prescription foran old problem. Maturitas, 72, 311e316.
Borg, G. (1998). Borg’s perceived exertion and pain scales. Champaign, IL: Human
Kinetics.
Boutcher, S. H. (2011). High-intensity intermittent exercise and fat loss. Journal of
Obesity, 2011, 868305.
Boyd, J. C., Simpson, C. A., Jung, M. E., & Gurd, B. J. (2013). Reducing the intensity andvolume of interval training diminishes cardiovascular adaptation but not
mitochondrial biogenesis in overweight/obese men. PLoS ONE, 8, e68091.
Brock, D. W., Chandler-Laney, P. C., Alvarez, J. A., Gower, B. A., Gaesser, G. A., &Hunter, G. R. (2010). Perception of exercise difﬁculty predicts weight regain informerly overweight women. Obesity, 18, 982e986.
Coats, E. M., Rossiter, H. B., Day, J. R., Miura, A., Fukuba, Y., & Whipp, B. J. (2003).
Intensity-dependent tolerance to exercise after attaining VO2 max in humans.
Journal of Applied Physiology, 95, 483e490.
Conraads, V. M., Pattyn, N., De Maeyer, C., Beckers, P. J., Coeckelberghs, E.,
Cornelissen, V. A., … Vanhees, L. (2015). Aerobic interval training and continuous training equally improve aerobic exercise capacity in patients with coronary artery disease: The SAINTEX-CAD study. International Journal of Cardiology,
179, 203e210.
Coyle, E. F. (2005). Very intense exercise-training is extremely potent and time
efﬁcient: A reminder. Journal of Applied Physiology, 98, 1983e1984.
De Feo, P. (2013). Is high-intensity exercise better than moderate-intensity exercise
for weight loss? Nutrition, Metabolism, and Cardiovascular Diseases, 23,1037e1042.
Del Vecchio, F. B., Gentil, P., Coswig, V. S., & Fukuda, D. H. (2015). Commentary:“Why sprint interval training is inappropriate for a largely sedentary population.” the satisfaction that moves us: Sprint interval training as an exercise
method for sedentary individuals. Frontiers in Psychology, 6, 1359.
Donnelly, J. E., Blair, S. N., Jakicic, J. M., Manore, M. M., Rankin, J. W., & Smith, B. K.
(2009). Appropriate physical activity intervention strategies for weight loss andprevention of weight regain for adults. Medicine and Science in Sports and Exercise, 41, 459e471.
Ekkekakis, P., & Dafermos, M. (2012). Exercise is a many-splendored thing but forsome it does not feel so splendid: Staging a resurgence of hedonistic ideas in
the quest to understand exercise behavior. In E. O. Acevedo (Ed.), The Oxford
handbook of exercise psychology (pp. 295e333). New York: Oxford University
Press.
Ekkekakis, P., Lind, E., Hall, E. E., & Petruzzello, S. J. (2008). Do regression-based
computer algorithms for determining the ventilatory threshold agree? Journalof Sports Sciences, 26, 967e976.
Ekkekakis, P., Lind, E., & Vazou, S. (2010). Affective responses to increasing levels of
exercise intensity in normal-weight, overweight, and obese middle-aged
women. Obesity, 18, 79e85.
Ekkekakis, P., Parﬁtt, G., & Petruzzello, S. J. (2011). The pleasure and displeasurepeople feel when they exercise at different intensities: Decennial update andprogress towards a tripartite rationale for exercise intensity prescription. Sports
Medicine, 41, 641e671.
Ekkekakis, P., Vazou, S., Bixby, W. R., & Georgiadis, E. (2016). The mysterious case of
the public health guideline that is (almost) entirely ignored: Call for a research
agenda on the causes of the extreme avoidance of physical activity in obesity.
Obesity Reviews, 17, 313e329.
Elliott, A. D., Rajopadhyaya, K., Bentley, D. J., Beltrame, J. F., & Aromataris, E. C.
(2015). Interval training versus continuous exercise in patients with coronary
artery disease: A meta-analysis. Heart Lung and Circulation, 24, 149e157.

9Ferguson, C., Whipp, B. J., Cathcart, A. J., Rossiter, H. B., Turner, A. P., & Ward, S. A.
(2007). Effects of prior very-heavy intensity exercise on indices of aerobic
function and high-intensity exercise tolerance. Journal of Applied Physiology, 103,812e822.
Flegal, K. M., Carroll, M. D., Kit, B. K., & Ogden, C. L. (2012). Prevalence of obesity andtrends in the distribution of body mass index among US adults, 1999-2010.
Journal of the American Medical Association, 307, 491e497.
Fletcher, G. F., Ades, P. A., Kligﬁeld, P., Arena, R., Balady, G. J., Bittner, V. A., et al.
(2013). Exercise standards for testing and training: A scientiﬁc statement fromthe American heart association. Circulation, 128, 873e934.
Fogelholm, M., Kukkonen-Harjula, K., Nenonen, A., & Pasanen, M. (2000). Effects ofwalking training on weight maintenance after a very-low-energy diet in premenopausal obese women: A randomized controlled trial. Archives of Internal
Medicine, 160, 2177e2184.
Fogelholm, M., Stallknecht, B., & Van Baak, M. (2006). ECSS position statement:
Exercise and obesity. European Journal of Sport Science, 6, 15e24.
Fredrickson, B. L., & Kahneman, D. (1993). Duration neglect in retrospective evaluations of affective episodes. Journal of Personality and Social Psychology, 65,
45e55.
Gaesser, G. A., & Angadi, S. S. (2011). High-intensity interval training for health andﬁtness: Can less be more? Journal of Applied Physiology, 111, 1540e1541.
Gaskill, S. E., Ruby, B. C., Walker, A. J., Sanchez, O. A., Serfass, R. C., & Leon, A. S.
(2001). Validity and reliability of combining three methods to determine
ventilatory threshold. Medicine and Science in Sports and Exercise, 33,
1841e1848.
Gibala, M. J., & McGee, S. L. (2008). Metabolic adaptations to short-term high-intensity interval training: A little pain for a lot of gain? Exercise and Sport Sciences
Reviews, 36, 58e63.
Gillen, J. B., & Gibala, M. J. (2014). Is high-intensity interval training a time-efﬁcient
exercise strategy to improve health and ﬁtness? Applied Physiolology Nutrition
and Metabolism, 39, 409e412.
Hardcastle, S. J., Ray, H., Beale, L., & Hagger, M. S. (2014). Why sprint interval training
is inappropriate for a largely sedentary population. Frontiers in Psychology, 5,1505.
Hardy, C. J., & Rejeski, W. J. (1989). Not what, but how one feels: The measurementof affect during exercise. Journal of Sport and Exercise Psychology, 11, 304e317.
Haskell, W. L., Lee, I. M., Pate, R. R., Powell, K. E., Blair, S. N., Franklin, B. A., et al.
(2007). Physical activity and public health: Updated recommendation for adults
from the American college of Sports medicine and the american heart association. Medicine and Science in Sports and Exercise, 39, 1423e1434.
Hazell, T. J., Olver, T. D., Hamilton, C. D., & Lemon, P. W. R. (2012). Two minutes ofsprint-interval exercise elicits 24-hr oxygen consumption similar to that of 30
min of continuous endurance exercise. International Journal of Sport Nutrition
and Exercise Metabolism, 22, 276e283.
Holloway, T. M., & Spriet, L. L. (2015). CrossTalk opposing view: High intensity interval training does not have a role in risk reduction or treatment of disease.
Journal of Physiology, 593, 5219e5221.
Hulens, M., Vansant, G., Lysens, R., Claessens, A. L., & Muls, E. (2001). Exercise capacity in lean versus obese women. Scandinavian Journal of Medicine and Sciencein Sports, 11, 305e309.
Hwang, C. L., Wu, Y. T., & Chou, C. H. (2011). Effect of aerobic interval training on
exercise capacity and metabolic risk factors in people with cardiometabolic
disorders: A meta-analysis. Journal of Cardiopulmonary Rehabilitation and Prevention, 31, 378e385.
Jones, A. M., Grassi, B., Christensen, P. M., Krustrup, P., Bangsbo, J., & Poole, D. C.
(2011). Slow component of VO2 kinetics: Mechanistic bases and practical applications. Medicine and Science in Sports and Exercise, 43, 2046e2062.
Jones, A. M., Vanhatalo, A., Burnley, M., Morton, R. H., & Poole, D. C. (2010). Criticalpower: Implications for determination of VO2max and exercise tolerance.
Medicine and Science in Sports and Exercise, 42, 1876e1890.
Juneau, M., Hayami, D., Gayda, M., Lacroix, S., & Nigam, A. (2014). Provocative issues
in heart disease prevention. Canadian Journal of Cardiology, 30, S401eS409.
Jung, M. E., Bourne, J. E., & Little, J. P. (2014). Where does HIT ﬁt? An examination of
the affective response to high-intensity intervals in comparison to continuous
moderate- and continuous vigorous-intensity exercise in the exercise intensityaffect continuum. PLoS ONE, 9, e114541.
Jung, M. E., Little, J. P., & Batterham, A. M. (2016). Commentary: Why sprint interval
training is inappropriate for a largely sedentary population. Frontiers in Psychology, 6, 1999.
Kelly, B., King, J. A., Goerlach, J., & Nimmo, M. A. (2013). The impact of high-intensity
intermittent exercise on resting metabolic rate in healthy males. European
Journal of Applied Physiology, 113, 3039e3047.
Kendzierski, D., & DeCarlo, K. J. (1991). Physical activity enjoyment Scale: Twovalidation studies. Journal of Sport and Exercise Psychology, 13, 50e64.
Kessler, H. S., Sisson, S. B., & Short, K. R. (2012). The potential for high-intensity
interval training to reduce cardiometabolic disease risk. Sports Medicine, 42,489e509.
Keteyian, S. J. (2012). Swing and a miss or inside-the-park home run: Which fate
awaits high-intensity exercise training? Circulation, 126, 1431e1433.
Kilpatrick, M. W., Greeley, S. J., & Collins, L. H. (2015). The impact of continuous andinterval cycle exercise on affect and enjoyment. Research Quarterly for Exercise
and Sport, 86, 244e251.
Kilpatrick, M. W., Jung, M. E., & Little, J. P. (2014). High-intensity interval training: A
review of physiological and psychological responses. ACSM's Health and Fitness
Journal, 18(5), 11e16.

10

E.S. Decker, P. Ekkekakis / Psychology of Sport and Exercise 28 (2017) 1e10

Levinger, I., Shaw, C. S., Stepto, N. K., Cassar, S., McAinch, A. J., Cheetham, C., et al.
(2015). What doesn't kill you makes you ﬁtter: A systematic review of highintensity interval exercise for patients with cardiovascular and metabolic diseases. Clinical Medicine Insights, Cardiology, 9, 53e63.
Little, J. P., Gillen, J. B., Percival, M. E., Safdar, A., Tarnopolsky, M. A., Punthakee, Z.,
et al. (2011). Low-volume high-intensity interval training reduces hyperglycemia and increases muscle mitochondrial capacity in patients with type 2 diabetes. Journal of Applied Physiology, 111, 1554e1560.
Little, J. P., Jung, M. E., Wright, A. E., Wright, W., & Manders, R. J. (2014). Effects ofhigh-intensity interval exercise versus continuous moderate-intensity exercise
on postprandial glycemic control assessed by continuous glucose monitoring inobese adults. Applied Physiology Nutrition and Metabolism, 39, 835e841.
Lucas, S. J., Cotter, J. D., Brassard, P., & Bailey, D. M. (2015). High-intensity interval
exercise and cerebrovascular health: Curiosity, cause, and consequence. Journalof Cerebral Blood Flow and Metabolism, 35, 902e911.
Lunt, H., Draper, N., Marshall, H. C., Logan, F. J., Hamlin, M. J., Shearman, J. P., et al.
(2014). High intensity interval training in a real world setting: A randomized
controlled feasibility study in overweight inactive adults, measuring change inmaximal oxygen uptake. PLoS ONE, 9, e83256.
Martinez, N., Kilpatrick, M. W., Salomon, K., Jung, M. E., & Little, J. P. (2015). Affective
and enjoyment responses to high-intensity interval training in overweight-toobese and insufﬁciently active adults. Journal of Sport & Exercise Psychology,
37(2), 138e149. http://dx.doi.org/10.1123/jsep.2014-0212.
Martins, C., Kazakova, I., Ludviksen, M., Mehus, I., Wisløff, U., Kulseng, B., et al.
(2016). High-intensity interval training and isocaloric moderate-intensity
continuous training result in similar improvements in body composition andﬁtness in obese individuals. International Journal of Sport Nutrition and Exercise
Metabolism, 26, 197e204.
€ ssner, S. (1997). Is walking for exercise too
Mattsson, E., Larsson, U. E., & Ro
exhausting for obese women? International Journal of Obesity and Related
Metabolic Disorders, 21, 380e386.
Milanovic, Z., Sporis, G., & Weston, M. (2015). Effectiveness of high-intensity interval training (HIT) and continuous endurance training for VO2max improvements: A systematic review and meta-analysis of controlled trials. Sports
Medicine, 45, 1469e1481.
O’Donovan, G., & Shave, R. (2007). British adults’ views on the health beneﬁts ofmoderate and vigorous activity. Preventive Medicine, 45(6), 432e435. http://dx.doi.org/10.1016/j.ypmed.2007.07.026.
Oliveira, B. R., Slama, F. A., Deslandes, A. C., Furtado, E. S., & Santos, T. M. (2013).
Continuous and high-intensity interval training: Which promotes higher
pleasure? PLoS ONE, 8, e79965.
Redelmeier, D. A., & Kahneman, D. (1996). Patients' memories of painful medical
treatments: Real-time and retrospective evaluations of two minimally invasive
procedures. Pain, 66, 3e8.
Rehn, T. A., Winett, R. A., Wisløff, U., & Rognmo, O. (2013). Increasing physical activity of high intensity to reduce the prevalence of chronic diseases andimprove public health. Open Cardiovascular Medicine Journal, 7, 1e8.
Rhodes, R. E., Fiala, B., & Conner, M. (2009). A review and meta-analysis of affective
judgments and physical activity in adult populations. Annals of Behavioral
Medicine, 38, 180e204.
Rhodes, R. E., & Kates, A. (2015). Can the affective response to exercise predict future
motives and physical activity behavior? A systematic review of published evidence. Annals of Behavioral Medicine, 49, 715e731.

Richards, J. C., Johnson, T. K., Kuzma, J. N., Lonac, M. C., Schweder, M. M.,
Voyles, W. F., et al. (2010). Short-term sprint interval training increases insulin
sensitivity in healthy adults but does not affect the thermogenic response to badrenergic stimulation. Journal of Physiology, 588, 2961e2972.
Saanijoki, T., Nummenmaa, L., Eskelinen, J. J., Savolainen, A. M., Vahlberg, T.,
Kalliokoski, K. K., et al. (2015). Affective responses to repeated sessions of highintensity interval training. Medicine and Science in Sports and Exercise, 47,2604e2611.
Sevits, K. J., Melanson, E. L., Swibas, T., Binns, S. E., Klochak, A. L.,
Lonac, M. C., … Bell, C. (2013). Total daily energy expenditure is increased
following a single bout of sprint interval training. Physiological Reports, 1,e00131.
da Silva, S. G., Elsangedy, H. M., Krinski, K., de Campos, W., Buzzachera, C. F.,
Krause, M. P., et al. (2011). Effect of body mass index on affect at intensities
spanning the ventilatory threshold. Perceptual and Motor Skills, 113, 575e588.
Skelly, L. E., Andrews, P. C., Gillen, J. B., Martin, B. J., Percival, M. E., & Gibala, M. J.
(2014). High-intensity interval exercise induces 24-h energy expenditure
similar to traditional endurance exercise despite reduced time commitment.
Applied Physiology, Nutrition, and Metabolism, 39, 845e848.
Smart, N. A., & Ismail, H. (2013). Is it safer and more beneﬁcial to work heart failure
patients harder? An editorial commentary. Clinical Cardiology, 36, 638e639.
Støylen, A., Conraads, V., Halle, M., Linke, A., Prescott, E., & Ellingsen, Ø. (2012).
Controlled study of myocardial recovery after interval training in heart failure,
SMARTEX-HF: Rationale and design. European Journal of Preventive Cardiology,
19, 813e821.
Tarumi, T., & Zhang, R. (2015). The role of exercise-induced cardiovascular adaptation in brain health. Exercise and Sport Sciences Reviews, 43, 181e189.
Thomas, S., Reading, J., & Shephard, R. J. (1992). Revision of the physical activity
readiness questionnaire (PAR-Q). Canadian Journal of Sport Sciences, 17,338e345.
Tjønna, A. E., Lee, S. J., Rognmo, Ø., Stølen, T. O., Bye, A., Haram, P. M., et al. (2008).
Aerobic interval training versus continuous moderate exercise as a treatment
for the metabolic syndrome: A pilot study. Circulation, 118, 346e354.
Tudor-Locke, C., Brashear, M. M., Johnson, W. D., & Katzmarzyk, P. T. (2010).
Accelerometer proﬁles of physical activity and inactivity in normal weight,
overweight, and obese U.S. men and women. International Journal of Behavioral
Nutrition and Physical Activity, 7, 60.
Wang, Y. C., McPherson, K., Marsh, T., Gortmaker, S. L., & Brown, M. (2011). Healthand economic burden of the projected obesity trends in the USA and the UK.
Lancet, 378, 815e825.
Weston, K. S., Wisløff, U., & Coombes, J. S. (2014). High-intensity interval training inpatients with lifestyle-induced cardiometabolic disease: A systematic review
and meta-analysis. British Journal of Sports Medicine, 48, 1227e1234.
Williams, D. M., Dunsiger, S., Ciccolo, J. T., Lewis, B. A., Albrecht, A. E., & Marcus, B. H.
(2008). Acute affective response to a moderate-intensity exercise stimulus
predicts physical activity participation 6 and 12 months later. Psychology ofSport and Exercise, 9, 231e245.
Williams, D. M., Dunsiger, S., Jennings, E. G., & Marcus, B. H. (2012). Does affective
valence during and immediately following a 10-min walk predict concurrent
and future physical activity? Annals of Behavioral Medicine, 44, 43e51.
Wisløff, U., Coombes, J. S., & Rognmo, Ø. (2015). CrossTalk proposal: High intensity
interval training does have a role in risk reduction or treatment of disease.
Journal of Physiology, 593, 5215e5217.