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Martins, Catia, Stensvold, Dorthe, Finlayson, Graham, Holst, Jens, Wisloff,Ulrik, Kulseng, Bard, Morgan, Linda, & King, Neil A.(2015)Effect of moderate- and high-intensity acute exercise on appetite in obeseindividuals.Medicine & Science in Sports & Exercise, 47 (1), pp. 40-48.

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https://doi.org/10.1249/MSS.0000000000000372

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https://eprints.qut.edu.au/80100/

https://doi.org/10.1249/MSS.0000000000000372

1

Title: Effect of moderate and high intensity acute exercise on appetite in obese individuals

Catia Martins1,2; Dorthe Stensvold3; Graham Finlayson4; Jens Holst5; Ulrik Wisloff3; Bård

Kulseng1,2; Linda Morgan6 and Neil A. King7

1 Obesity Research Group, Department of Cancer Research and Molecular Medicine, Faculty

of Medicine, Norwegian University of Science and Technology, Trondheim, Norway; 2 Center for Obesity, Department of Surgery, St. Olav Hospital – Trondheim University

Hospital, Trondheim, Norway 3 K.G. Jebsen Center for Exercise in Medicine at Department of Circulation and Medical

Imaging, Trondheim, Norway. 4 BioPsychology Group, Institute of Psychological Sciences, University of Leeds, Leeds,

United Kingdom

5 Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark

6 Department of Nutrition and Metabolism, University of Surrey, Guildford, UK 7 Institute of Health and Biomedical Innovation, Queensland University of Technology,

Brisbane, Australia

Corresponding author: Catia Martins

Institutt for Kreftforskning og molekylær medisin

Medisinsk teknisk forskningssenter

Olav Kyrres gt. 9, N-7489 Trondheim - Norway

email: [email protected]

Running title: Acute exercise and appetite in the obese

Word count: 3970 words

Funding: Liaison Committee between the Central Norway Regional Health Authority (RHA)

and the Norwegian University of Science and Technology (NTNU).

Conflict of interest: The authors declare that there is no conflict of interest that would

prejudice the impartiality of this scientific work.

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Abstract:

Purpose: The impact of acute exercise, and exercise intensity, on appetite control in obese

requires further study. The aim of this study was to compare the effects of acute isocaloric

bouts (250kcal) of high-intensity intermittent cycling (HIIC) and moderate-intensity

continuous cycling (MICC), or short-duration HIIC (S-HIIC) (125kcal), and a resting control

condition, on the appetite hormones responses, subjective feelings of appetite, energy intake

(EI) and food reward in overweight/obese individuals.

Methods: Randomized cross-over study in twelve overweight/obese volunteers. Participants

were assigned to the control, MICC, HIIC and S-HIIC conditions, 1 week apart, in a counter-

balanced order. Exercise was performed 1 hour after a standard breakfast. An ad libitum test

lunch was served 3h after breakfast. Fasting/postprandial plasma samples of insulin, acylated

ghrelin (AG), polypeptide YY3-36 (PYY3-36) and glucagon-like peptide 1 (GLP-1) and

subjective feelings of appetite were measured every 30 minutes for 3h. Nutrient and taste

preferences were measured at the beginning and end of each condition using the Leeds Food

Preference Questionnaire

Results: Insulin levels were significantly reduced and GLP-1 levels significantly increased

during all exercise bouts, compared with rest. AG plasma levels were lower in the MICC and

HIIC, but not S-HIIC, compared with control. There were no significant differences for PYY3-

36 plasma levels, hunger or fullness ratings, EI or food reward.

Conclusion: Our findings suggest that, in overweight/obese individuals, isocaloric bouts of

moderate or high-intensity exercise lead to a similar appetite response. This strengthens

previous findings in normal-weight individuals that acute exercise, even at high intensity does

not induce any known physiological adaptation that would lead to increased EI.

Keywords: ghrelin, polypeptide YY, glucagon-like peptide 1, food reward

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Introduction:

1. Obesity has become a global epidemic worldwide (33). This picture is undeniably linked to a

decrease in physical activity (PA) levels over the past few decades, driven by dramatic

changes in lifestyle (31). Although the role of PA in preventing weight gain is widely

accepted (12), its impact on weight loss, in the absence of energy restriction, seems to be only

modest (25). The ability of exercise to create a negative energy balance (EB) relies directly on

its ability to increase energy expenditure (EE), but also indirectly on its potential to modulate

energy intake (EI) and appetite (16, 18). It has already been shown that the lower than

expected weight loss experienced by some in response to an exercise intervention can be

explained, at least partially, by a compensatory increase on EI (15).

2. Appetite is controlled by a series of complex processes in the brain and multiple hormones

released peripherally (for a review see Blundell, 2006 (3)). Determining how acute exercise

impacts on appetite will provide a better understanding of its role on food intake and body

weight homeostasis. Moreover EI responses to acute exercise may also be influenced by

changes in the hedonic system, with changes for example in food preferences (2).

3. The majority of the studies, in normal-weight individuals, indicates that acute exercise does

not increase hunger or EI, even at high intensities, and that exercise is, therefore, able to

induce a short-term negative EB (18). Acute exercise does not seem to influence total ghrelin

(TG) (an orexigenic hormone) concentrations (18), and several studies have shown a

significant suppression in the active component of the hormone, acylated ghrelin (AG), in

response to high-intensity exercise (5, 13, 20), but not brisk walking (14). Moreover, exercise

has been shown to increases the release of satiety hormones such as polypeptide YY (PYY)

and glucagon-like peptide 1(GLP-1) in normal-weight individuals (19). Overall, the available

evidence suggests that acute exercise does not induce physiological adaptations leading to

increased EI in the short-term (18).

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4. However, few studies have been performed in the obese. Ueda and colleagues (2009) reported

no change in TG and a significant increase in PYY and GLP-1 plasma levels with moderate-

intensity exercise (compared with rest), in normal-weight and obese men (29). Marzullo and

collaborators (2008) also showed no change in TG with maximal exercise, in normal-weight

and obese individuals, despite a significant suppression in AG (20). Finally, Westerterp-

Plantenga and collaborators (1997) reported a significant suppression in hunger and EI after

2h of cycling at 60% max workload in normal-weight and obese men (32).

5. Three recent reviews/meta-analysis, including obese individuals, have addressed the impact of

exercise on appetite (8, 23, 24). They have concluded that there is little or no evidence that

acute exercise affects energy or macronutrient intake, therefore, being able to produce a short-

term negative energy deficit (8, 23). Moreover, acute exercise is associated with positive

changes in appetite-related hormones, supressing levels of AG, while simultaneously

increasing levels of satiety peptides (PYY, GLP-1 and pancreatic polypeptide) (24).

6. High-intensity intermittent exercise, in which high intensity work is interspersed with low-

intensity work, has been shown to be a time saving and sustainable exercise method, even in

the untrained obese patient, with good results on body weight and composition,

cardiovascular fitness and insulin resistance (4). However, few studies have compared the

impact of different intensities of acute bouts of exercise on appetite, and they were performed

in trained normal-weight men (6, 7, 28) and did not standardise the energy expenditure of the

exercise bouts (6, 28). In a recently published study, Sim and colleagues (2013) reported a

lower ad libitum EI after high-intensity intermittent cycling (HIIC) and very-HIIC, compared

with control and a significantly lower AG plasma levels after very-HIIC compared with the

other conditions in overweight inactive men (26). However, this study included men only,

who were not obese, and exercise was performed in fasting. This has limitations concerning

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generalization of the results to other populations and in conditions where exercise is

performed in the postprandial state, which is the case in the majority of the situations.

7. The primary objective of this study was to investigate the effects of acute isocaloric bouts of

HIIC and moderate-intensity continuous cycling (MICC) (250kcal) (and a short bout of HIIC

(average 9 minutes – 125kcal)), in comparison with a resting control condition, on the

postprandial release of appetite-regulating hormones, subjective feelings of appetite,

subsequent EI and food reward in overweight/obese individuals. We hypothesized that an

isocaloric session of HIIC would result in a larger reduction in AG and hunger, a larger

increase in satiety peptides and a greater reduction in subsequent EI compared with MICC

(and that the short-bout of HIIC would produce the same appetite changes as MICC).

8.

Methods:

Subjects

9. Twelve healthy but sedentary overweight/obese volunteers (five males and seven females),

not currently dieting to lose weight and weight stable on the previous 3 months (≤2kg

variation), were recruited for this study. Participants had an average (±SD) age of 33.4±10.0

years, an average (±SD) BMI of 32.3±2.7 kg/m2 and an average (±SD) VO2max of 30.5±4.9

ml/kg/min.

10. The exclusion criteria were as follows: a restraint score derived from the Three Factor Eating

Behaviour Questionnaire>12 (TFEQ) (30), history of coronary heart disease, type 1 or type 2

diabetes, anaemia, gout, depression or other psychological disorders, eating disorders, drug or

alcohol abuse within the last two years, current medication known to affect appetite or induce

weight loss and hypertension.

11. This study was conducted according to the guidelines laid down in the Declaration of Helsinki

and was approved by the regional Ethics Committee (Midt-Norge, Trondheim, Norway) (Ref.

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2010/444-1). Written informed consent was obtained from all participants before enrolling in

the study.

Study design

12. This was a randomised cross-over study with four conditions. Participants acted as their own

controls and were assigned to the four experimental conditions: control, MICC, HIIC and S-

HIIC, 1 week apart, in a counter-balanced order.

Detailed protocol

13. Participants were asked to attend the Research Unit five times: one preliminary familiarisation

session and four experimental conditions: control, MICC and HIIC isocaloric sessions

designed to induce a 250kcal energy deficit and S-HIIC designed to induce an energy deficit

of 125kcal.

14. In order to reduce the inherent variability, participants were instructed to refrain from

exercising and from drinking alcohol and caffeine 24h prior to and on the day of each

experimental condition. Participants were also asked to record on a food diary everything they

ate and drank for dinner on the day before the first experimental condition and asked to

consume exactly the same type and amount of food for dinner on the day before the other

three conditions. Participants were interviewed in the morning of each experimental condition

in order to check their compliance with these requirements.

15. In the preliminary session, anthropometric data were collected and cardiovascular fitness

(VO2max) was measured on a cycle ergometer (Ergomedic 839E, Monark 2008, Sweden)

using the system Oxigen Pro (Viasys Healthcare, Hoechberg, Germany). The test started with

a 5 min warm up with a resistance of 50W and afterwards the workload was gradually

increased by 20W every 2 minutes and participants asked to maintain a cadence between 60-

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70 rpm. An expiratory exchange ratio (RER) of 1.05 or above, was set as the criterion for

achieving VO2max. Heart rate was continuously recorded during the test using a heart rate

(HR) monitor (Polar type 610; Polar Electro Oy). Maximal heart rate was defined by adding

five beats to the highest heart rate value obtained during the VO2max test.

16. For the four experimental conditions, participants were asked to arrive at approximately 8.00,

having fasted for at least 10 hours (water was permitted ad libitum during this time), and a

cannula was inserted into an antecubital vein. A fasting blood sample was taken and

participants were instructed to consume a standard breakfast (time = zero), consisting of

bread, orange juice, milk, cheese, and jam (600 kcal, 17% protein, 35% fat, and 48%

carbohydrate) within 10 min. After that, serial blood samples were taken at regular intervals

for a period of 3h (30, 60, 80, 100, 120, 150 and 180 minutes) and analysed for haemoglobin,

haematocrit, insulin, AG and PYY3-36 and GLP-1.

17. Participants were asked to rate their subjective feelings of hunger, fullness and desire to eat

using 10cm visual analogue scales (VAS) throughout each study morning, at different time

points (right before each blood sample), as previously described (11). The reward value of

food was measured using a computer-based behavioural procedure called the Leeds Food

Preference Questionnaire (LFPQ) (10), immediately before and after each condition. The

LFPQ provides measures of explicit liking (EL), implicit wanting (IW) and relative food

preference (FP) according to the shared sensory properties of foods.

18. Three hours after breakfast, participants were placed in individual rooms, presented with a

standardized lunch and instructed to rate the taste and palatability of the food presented (and

afterwards to eat as much or as little as they wanted, from the food presented). The

standardized ad libitum lunch test meal consisting of 10 ¼ of sandwiches, 300g of strawberry

yoghurt and 60g of crisps, in excess of expected consumption (1358kcal, 53g P, 61g fat, 133g

carbohydrates). Participants were asked in advance to rank four sandwiches’ fillings (ham,

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cheese, salami and liver paste) by order of preference. Participants were then offered their

second most liked option.

19. Participants were then allowed to leave the Research Unit, but were asked to use an

AiperMotion 440PC accelerometer (Aipermon GmbH & Co. KG, Munich, Germany) to

measure PA levels, until retiring to bed. They were also asked to write down everything they

ate and drank for the rest of the day in a food diary, to estimate cumulative EI over that day

(lunch plus subsequent EI till bedtime). Dietary analysis was performed using Mat på Data

5.0 program (Landsforeningen for kosthold og helse, Oslo, Norway).

Experimental conditions

20. During the resting condition, participants remained seated, but were allowed to read, write or

use a computer. During the exercise conditions, participants performed one of three exercise

sessions, one hour after breakfast. Water was allowed ad bibitum in all four conditions. Each

exercise session started with a 5 min warm-up and finished with a 5-min cool down. The

MICC consisted of cycling at 70% maxHR. The HIIC consisted of bouts of 8s sprinting (all

out) and 12 s of turning the pedals very slowly (20-30 rpm). Participants were asked to follow

a pre-recorded tape which prompted them to start and stop cycling so that the work:rest ratio

was 8s:12s. The resistance used was that needed to increase the participant’s HR to 85-90%

maxHR. The S-HIIC was the same as the HIIC but for only half duration. The duration of

each exercise session was individually designed (based on data collected during the VO2max

test), in order to induce a 250kcal (MICC and HIIC) or 125kcal (S-HIIC) energy deficit. HR

was measured continuously, during each exercise session, using a HR monitor (Polar F1 –

Polar Electro Oy, Kempele, Finland). Average duration of each exercise session was 27±6,

18±3 and 9±2 minutes for the MICC, HIIC and S-HIIC sessions, respectively. Average HR

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during exercise was 133±8 (71±1% maxHR), 162±11 (86±2.5% maxHR) and 160±9

(85±3.5% maxHR) beats per minute, for the MICC, HIIC and S-HIIC sessions, respectively.

Hormone and metabolite measurement

21. Venous blood was collected into regular EDTA tubes for the measurement of haemoglobin

and haematocrit and EDTA-coated tubes containing 500 KIU aprotinin (Pentapharm, Basel,

Switzerland)/ml whole blood for the measurement of insulin and gut peptides. Haemaglobin

and haematocrits were measured using standard haematological procedures. The other EDTA

tubes containing aprotinin were then centrifuged at 2000 g for 10 minutes and kept at –80° C

for later analyses. For the measurement of AG, 50 μl of a 1 N hydrochloric acid solution and

10 μl of Phenylmethylsulfonyl fluoride (Sigma, Schnelldorf, Germany) (10 mg/ml of

isopropanol) was added to each ml of plasma immediately after centrifugation. All samples

were batch analysed at the end of the study to reduce inter-assay variability.

22. Insulin, AG and PYY3-36 were quantified using human-specific RIA kits (Linco Research, St

Charles, USA) and GLP-1 using an in house RIA method. GLP-1 concentrations in plasma

were measured by RIA after extraction of plasma with 70 % ethanol (vol/vol, final

concentration) as previously described (20). Carboxy-terminal GLP-1 immunoreactivity was

determined using antiserum 89390 which has an absolute requirement for the intact amidated

carboxy-terminus of GLP-1 (7-36) amide and crossreacts less than 0.01% with carboxy-

terminally truncated fragments and 89% with GLP-1 (9-36) amide, the primary metabolite of

dipeptidyl-peptidase IV mediated degradation. The sum of the two components (total GLP-1

concentration) reflects the rate of secretion of the L-cell.

23. The sensitivity of the assays was 14 pmol/L for insulin, 7.8 pg/ml for AG, 1 pmol/L for GLP-

1 and 2 pmol/l for PYY3-36. All samples were assayed in duplicate and samples from the

10

same participant (all 4 legs) were analysed in the same batch. The intra-assay coefficient of

variation was of <10% for insulin and AG and <5% for GLP-1 and PYY3-36.

Statistical analysis

24. Statistical analysis was carried out using SPSS version 13.0 (SPSS Inc., Chicago, IL). All the

variables were checked regarding their normal distribution using the Shapiro-Wilk test and

data expressed as mean ± SEM, unless otherwise stated.

25. Differences in fasting/postprandial levels of metabolites and hormones and appetite sensations

between the experimental conditions were assessed by a repeated measure ANOVA using

experimental condition and time as independent variables. Due to significant differences in

hemoglobin plasma levels and hematocrit (see results section) among conditions, suggesting

hemoconcentration during the exercise legs, plasma levels of the appetite hormones measured

were adjusted for hematocrit (by multiplying by baseline hematocrit/hematocrit at a specific

time point). The area under the curve (AUC) for plasma levels of appetite related hormones

and subjective feeling of appetite was calculated from before to 180 min after breakfast using

the trapezoidal rule (baseline measurements were taken into account). Differences among

experimental conditions were assessed by repeated measures ANOVA. Post hoc analysis,

with Bonferroni adjustment, was used to perform multiple comparisons.

26. Relative energy intake (REI), at the lunch test meal, was calculated by subtracting the

estimated EE during the exercise and rest sessions (180 minutes) from their respective lunch

EI. EE during the three hours at the Research Unit was estimated based on the assumption that

participants were allowed to read, write, work with the computer, etc, corresponding to a

MET=1.3 (1). EE during the MICC and HIIC was the same as the control condition + 250kcal

and for the S-HIIC, the same as the control condition + 125kcal. Differences in absolute and

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relative EI and macronutrient intake at lunch, and absolute energy and macronutrient intake

throughout the day among conditions, were assessed by repeated measured ANOVA. Post hoc

analysis, with Bonferroni adjustment, was used to perform multiple comparisons.

27. The reward value of food (explicit liking and implicit wanting response measures and relative

food preference) was analyzed using two 4x2 design ANOVA (experimental condition x time

(pre/post) for high fat relative to low fat food.

Results:

Hemoglobin and hematocrit

28. Hemoglobin plasma levels and hematocrit changes over time in the four conditions can be

seen in figure 1. There was a significant effect of time (P<0.0001) and a condition*time

interaction (P<0.0001) on both hemoglobin and hematocrit. Hemoglobin plasma levels

experienced a peak during exercise (quickly returning to control levels once the exercise

stopped) in the three exercise conditions (Figure 1a). A similar pattern was observed for

hematocrit (Figure 1b).

Appetite-related hormones

29. Plasma levels of insulin, AG, PYY3-36 and GLP-1 overtime in the different conditions can be

seen in figure 2.

30. A significant effect of time (P<0.0001) and a condition*time interaction (P<0.0001) were

observed on insulin plasma levels, but no main effect of condition (P>0.05) (Figure 2a).

Insulin plasma levels showed a peak at t=30 minutes and decreased gradually afterwards in

the control rest condition. In the exercise conditions, a pronounced reduction was observed

12

during the exercise period (60-80 minutes), with an increase being observed shortly

afterwards. No significant effect of condition was observed on insulin AUC (see

supplementary table 1).

31. A significant effect of time (P<0.0001) and condition (P<0.001), but no interaction, were

observed on AG plasma levels (Figure 2b). AG plasma levels decreased after breakfast

consumption with a nadir between 60-100 minutes and experienced a gradual increase

afterwards. Moreover, AG plasma levels were significantly reduced in the MICC and HIIC

conditions (P<0.05) (but not S-HIIC), compared with control. No significant difference was

observed in AG plasma levels between the MICC and HIIC conditions. A significant effect of

condition was observed on AG AUC (P=0.001), with AG AUC being significantly lower in

the MIIC and HIIC compared with control (P=0.02 and P=0.037, respectively) (see


32. A significant effect of time (P<0.0001), but no effect of condition or interaction, was

observed on PYY3-36 plasma levels (Figure 2c), which increased gradually following breakfast

consumption. No significant effect of condition was observed on PYY AUC (see


33. A significant effect of time (P<0.0001) and a condition*time interaction (P<0.0001), but no

main effect of condition (P>0.05), were observed on GLP-1 plasma levels. GLP-1 plasma

levels peaked at around 30 minutes and decreased afterwards in the control rest condition.

GLP-1 plasma levels were higher in the exercise conditions, compared with the control rest

condition, during and in the post-exercise period. No significant effect of condition was

observed on GLP-1 AUC (see supplementary table 1).

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Subjective feelings of appetite and subsequent food intake

34. Subjective feelings of appetite can be seen in figure 3.

35. There was a significant effect of time (P<0.0001), but no effect of condition or interaction on

hunger and fullness ratings (figure 3a and 3b). For desire to eat, there was a significant effect

of time (P<0.001) and a time*condition interaction (P<0.05), but no main effect of condition

(figure 3c). Desire to eat ratings decreased immediately after breakfast consumption and

decreased afterwards and were lower in the exercise conditions compared with rest, during the

exercise period. No significant effect of condition was observed for hunger, fullness or desire

to eat AUC (see table, SDC1. AUC for subjective feelings of appetite and appetite-related

hormones in the different conditions).

36. Energy and macronutrient intake at lunch, after each condition, and throughout the day can be

seen in table 1. There were no significant differences in absolute energy or macronutrient

intake, at lunch or throughout the day, among conditions. There was a significant effect of

condition on REI at lunch (P<0.0001). Post hoc analysis showed that REI in the control

condition was significantly higher than in the exercise conditions (P<0.0001 for MICC,

P=0.002 for HIIC and P=0.01 for S-HIIC). REI after MIIC was also significantly lower than

after the S-HIIC (P<0.0001).

Physical activity levels throughout the day after each experimental condition

37. Time spent on different activities, throughout the day, in the different conditions can be seen

in table 2. No significant differences were observed on sedentary time or time spent walking

or fast walking among conditions. A significant effect of condition was observed on time

spent active (P=0.029). Further post hoc analysis, however, did not reveal any significant

difference in active time among conditions.

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Food Reward

38. Explicit liking, implicit wanting and relative preference scores can be seen in table 3. Mean

scores were positive in all experimental conditions indicating that HF foods were more

rewarding, on average, than LF foods. There were no significant differences in the reward

value of high fat foods between conditions or over time (and no interaction between condition

and time) according to measures of explicit liking, implicit wanting or relative preference.

Discussion:

39. To the best of our knowledge, this is the first study to evaluate the role of exercise intensity on

appetite responses to acute bouts of exercise in overweight/obese individuals. Our hypothesis

that an isocaloric session of HIIC would result in a larger reduction in AG and hunger, a

larger increase in satiety peptides and a greater reduction in subsequent EI compared with

MICC was not confirmed.

40. In one of the few studies performed in obese individuals, Ueda and colleagues (2009) showed

that 60 minutes of cycling at 50% VO2max leads to a significant suppression in insulin, a

significant increase in PYY and GLP-1, and no changes in TG or subjective appetite feelings

in obese men (29). It is difficult to ascertain why, in the present study, exercising at an even

higher intensity was unable to increase PYY3-36 plasma levels. However, given the larger

exercise-induced energy deficit in Ueda and colleagues (2009) study, compared with ours

(~600kcal compared with 250kcal), it is possible that a larger energy deficit would be needed

to induce an increase in the postprandial release of PYY. Moreover, it is difficult to compare

studies which measured total PYY (PYY1-36) with studies measuring its active component

PYY3-36, since it remains unknown the conversion rate of total PYY (PYY1-36) to PYY3-36 and

only PYY3-36 has satiety properties.

15

41. In contrast to the majority of the studies performed in normal-weight individuals (18), a

transient suppression of hunger during exercise was not observed in the present study.

However, subjective feelings of desire to eat were lower during exercise (compared with rest),

regardless of the exercise condition. Westerterp-Plantenga and colleagues (1997), in a study

including both normal-weight and obese men, reported a significant suppression of hunger

after 2h of cycling at 60% of max workload (compared with a resting condition).

Unfortunately, analysis was not performed separately in obese men (32). Again, it is possible

that the larger exercise-induced EE in that study, compared with ours, has contributed to the

differences in outcome.

42. Absolute energy and macronutrient intake at the lunch test meal was similar regardless of the

experimental condition. However, REI was negative and significantly lower after the exercise

conditions compared with control. No significant differences were observed in absolute

energy and macronutrient intake throughout the day among conditions. However, taking into

account that sedentary and active time also did not differ among conditions, a lower REI and

subsequent negative EB, would be expected after acute exercise. This is in accordance with

Ueda and colleagues (2009) study, where a reduction in absolute and relative EI after 60

minutes of cycling at 50%VO2max, was reported in obese men (29).

43. Few studies have investigated the impact of exercise intensity on appetite. Ueda and

colleagues (2009) (28) looked at the impact of cycling at 50% or 75%VO2max (or rest) for 30

min on PYY3-36 and GLP-1 plasma levels, in normal-weight trained men. They reported a

larger increase in PYY3–36 plasma levels at higher intensity, despite a similar increase in GLP-

1 levels and a similar reduction in absolute EI and hunger feelings in both exercise conditions

(28). Kissileff and colleagues (1990) looked at the impact of strenuous (90 W) or moderate

(30 W) intensity cycling for 40 minutes (or rested) on food intake 15 minutes afterwards, in

normal-weight or overweight women. Food intake after exercise was significantly less after

16

the strenuous than after the moderate exercise in the normal-weight women but was similar in

obese women (17). The above evidence seems to suggest that high intensity exercise would,

not only, induce a larger suppression in orexigenic signals (AG), but also a larger release of

satiety signals (PYY3-36). However, the two last mentioned studies (17, 28) used non-

isocaloric bouts of exercise. Therefore, it is impossible to ascertain if the differences are due

to exercise intensity or to the larger energy deficit induced by the high-intensity exercise bout.

A recently published study in trained normal-weight men, using isocaloric bouts of HIIC and

MICC showed a significant suppression of hunger and a significant increase in PYY3-36

concentrations during/after exercise, especially during the HIIT, and no difference in ad

libitum EI (7).

44. In the present study, in overweight/obese individuals, using isocaloric bouts of moderate and

high intensity exercise, no significant impact of exercise intensity was observed on appetite

hormones, subjective feelings of appetite or EI. Exercise intensity, by itself, does not seem, at

least in overweight/obese individuals, to have an impact on appetite. In a recently published

study, Sim and colleagues (2013) randomly assigned overweight sedentary men to isocaloric

bouts of MICC (60% VO2peak), HIIC (60 s at 100% VO2peak: 240 s at 50% VO2peak), very-HIIC

(15 s at 170% VO2peak:60 s at 32% VO2peak) and control in a counterbalanced order. They

showed, as in our study, no differences in subjective appetite among conditions, but a lower

ad libitum EI after HIIC and very-HIIC compared with control and significantly lower AG

plasma levels after very-HIIC compared with the other conditions (26). However, that study

recruited overweight men and the exercise was performed in fasting. Moreover, the much

higher exercise intensity employed in that study, compared to ours, at levels that would be

difficult to sustain in the obese population, is likely to explain the different outcomes.

45. Few studies on the effects of exercise on appetite have included measures of food reward.

Finlayson et al (2009) reported an increase in implicit wanting for foods varying in fat content

17

and sweet taste, after moderate intensity cycling (compared to no exercise), but only in those

participants who increased their EI after exercise (9). Taylor & Oliver (2009) reported that

exercise transiently decreased cravings for chocolate (compared with rest) (27). In the present

study, we found no difference in liking, implicit wanting or relative preference for high fat

food relative to low fat food. These findings suggest that the overall mean pattern of food

reward was stable. However, the large standard deviation of scores indicates a broad range of

between-subject variability.

46. Our study presents with both strengths and limitations. The main strength of our study is its

design (crossover) and the fact that we measured several aspects of appetite (subjective

feelings, plasma levels of several appetite-related hormones, EI and food reward). As a

limitation, we have not accounted for phase of menstrual cycle, known to impact on energy

and macronutrient intake (22) and food reward (21, 22). However, given our design

(crossover randomised with 4 legs), we believe phase of menstrual cycle had a minor impact

on our results. Even though we aimed to look at the impact of exercise intensity on appetite,

the MICC and HIIC differed both in intensity and continous/discontinuous. However, given

that the intervals of active resting in the HIIC were so short (12s), the HR was all the time at

85-90% maxHR. It would be impossible to perform continuous high intensity exercise

inducing an energy expenditure of 250kcal in this patient group (inactive overweight/obese

individuals). Our protocol with exercise (or rest) being performed one hour after breakfast

and, the lunch test meal being presented three hours after breakfast, was used in order to

simulate a typical day, since exercise is usually performed in the postprandial state. Several

other studies looking at the impact of acute exercise on appetite have used a similar order of

events (19, 28, 29, 32).

47. In conclusion, our findings show that in overweight/obese individuals, acute isocaloric bouts

of moderate or high-intensity exercise lead to a similar appetite response. Both suppress

18

insulin and AG and increase the postprandial release of GLP-1, without affecting PYY3-36

plasma levels and have no impact on hunger or fullness, despite reducing desire to eat. This

together with a significant reduction in REI in all exercise conditions, and no changes in

activities patterns throughout the day, strengthen previous findings in normal-weight

individuals that acute exercise, even at high intensity, is able to induce a negative EB, without

stimulating physiological compensatory adaptations at the level of the appetite control system.

Acknowledgements:

48. Catia Martins was supported by a PostDoctoral grant from the Liaison Committee between

the Central Norway Regional Health Authority (RHA) and the Norwegian University of

Science and Technology (NTNU). We would like to thank all the participants that took part in

this study for their time and enthusiasm and Mrs. Sissel Salater for her help with cannulation.

The results of the present study do not constitute endorsement by ACSM.

Conflict of interest:

49. The authors declare that there is no conflict of interest that would prejudice the impartiality of

this scientific work.

19

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Figures legend:

Figure 1a. Hemoglobin plasma level profiles (g/dl), after a 600kcal breakfast, for: control (♦),

moderate intensity continuous cycling (MICC) (□), high intensity intermittent cycling (▲) and

short-duration HIIC (SHIIC) (X). Values represent means ± SEM for 12 subjects. Repeated

measures ANOVA showed a significant effect of time (P<0.0001) and a significant

condition*time interaction (P<0.0001).

Figure 1b. Hematocrit level profiles after a 600kcal breakfast for: control (♦), moderate

intensity continuous cycling (MICC) (□), high intensity intermittent cycling (▲) and short-

duration HIIC (SHIIC) (X). Values represent means ± SEM for 12 subjects. Repeated



Figure 2a. Insulin plasma level profiles (pmol/L) after a 600kcal breakfast for: control (♦),





24

Figure 2b. Acylated ghrelin plasma level profiles (pg/ml), after a 600kcal breakfast, for:

control (♦), moderate intensity continuous cycling (MICC) (□), high intensity intermittent

cycling (▲) and short-duration HIIC (SHIIC) (X). Values represent means ± SEM for 12

subjects. Repeated measures ANOVA showed a significant effect of time (P<0.0001) and

condition (p<0.001), but no interaction

Figure 2c. PYY plasma level profiles (pmol/L), after a 600kcal breakfast for: control (♦),



measures ANOVA showed a significant effect of time (P<0.0001), but no effect of condition

or interaction.

Figure 2d. GLP-1 plasma level profile (pmol/L), after a 600kcal breakfast, for: control (♦),





Figure 3a. Profiles of subjective feelings of hunger (cm), after a 600kcal breakfast, for:



subjects. Repeated measures ANOVA showed a significant effect of time (P<0.0001), but no

effect of condition or interaction.

25

Figure 3b. Profiles of subjective feelings of fullness (cm), after a 600kcal breakfast, for:



subjects. Repeated measures ANOVA showed a significant effect of time (P<0.0001), but no

effect of condition or interaction.

Figure 3c. Profiles of subjective feelings of desire to eat (cm), after a 600kcal breakfast, for:



subjects. Repeated measures ANOVA showed a significant effect of time (P<0.0001), and a

time*condition interaction (p<0.05).

26

Table . SDC1. AUC for subjective feelings of appetite and appetite-related hormones in the

different conditions

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