breakfast consumption and exercise interact to affect cognitive performance and mood later in the...
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Breakfast consumption and exercise interact to affect cognitive performance and
mood later in the day: a randomized controlled trial
R.C. Veasey, J.T. Gonzalez, D.O. Kennedy, C.F. Haskell, E.J. Stevenson
PII: S0195-6663(13)00148-7
DOI: http://dx.doi.org/10.1016/j.appet.2013.04.011
Reference: APPET 1817
To appear in: Appetite
Received Date: 29 October 2012
Revised Date: 12 April 2013
Accepted Date: 14 April 2013
Please cite this article as: Veasey, R.C., Gonzalez, J.T., Kennedy, D.O., Haskell, C.F., Stevenson, E.J., Breakfast
consumption and exercise interact to affect cognitive performance and mood later in the day: a randomized controlled
trial, Appetite (2013), doi: http://dx.doi.org/10.1016/j.appet.2013.04.011
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Breakfast consumption and exercise interact to affect cognitive performance and mood 1
later in the day: a randomized controlled trial 2
R.C.Veaseya,*, J. T. Gonzalez
a, D.O. Kennedy
a, C.F. Haskell
a, E.J. Stevenson
a 3
aBrain, Performance and Nutrition Research Centre, Faculty of Health and Life Sciences, 4
Northumbria University, Newcastle, Tyne and Wear, NE18ST, UK. 5 6 7 *Corresponding author: [email protected] (Rachel Veasey) 8
9 Not for publication: +44 (0)191 243 7253 10 11
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Abstract 33
The current study assessed the interactive effect of breakfast and exercise on cognition and 34
mood. Twelve active males completed four trials; no breakfast-rest, breakfast-rest, no 35
breakfast-exercise or breakfast-exercise in a randomized, cross-over design. The trials 36
consisted of; breakfast or fast, a 2h rest, exercise (treadmill run) or equivalent rest, a 37
chocolate milk drink, a 90min rest and an ad libitum lunch. Cognitive performance and 38
mood were recorded frequently throughout each trial. Data was analysed as pre-exercise/rest, 39
during and immediately post exercise/rest and post-drink. No effects were found prior to 40
consumption of the drink. Post-drink, fasting before exercise increased mental fatigue 41
compared to consuming breakfast before exercise and fasting before rest. Tension increased 42
when breakfast was consumed at rest and when exercise was undertaken fasted compared to 43
omitting breakfast before rest. Breakfast before rest decreased Rapid Visual Information 44
Processing task speed and impaired Stroop performance. Breakfast omission improved Four 45
Choice Reaction Time performance. To conclude, breakfast before exercise appeared 46
beneficial for post-exercise mood even when a post-exercise snack was consumed. Exercise 47
reversed post-breakfast cognitive impairment in active males. 48
49
Trial registration: clinicaltrials.gov NCT01229345 50
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Keywords 52
Breakfast; Exercise; Cognition; Mood; Active males 53
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Introduction 57
Past research has explored the effects of pre-exercise nutrition on physical performance, 58
forming a set of guidelines for athletes and the active population to follow. For example, it is 59
recommended that carbohydrate is consumed prior to exercise to improve endurance capacity 60
(American Dietetic Association, 2009) . However, achieving optimal physical performance is 61
often not the sole motivation for exercise. Performance is a multi-dimensional paradigm, 62
which also encompasses aspects of cognition and mood. An acute bout of sub-maximal 63
exercise has been shown to improve some facets of cognitive performance, such as reaction 64
time (Etnier, et al., 1997) and decision making (Adam, Teeken, Ypelaar, Verstappen, & Paas, 65
1997; McMorris & Graydon, 1996), as well as mood (Scully, Kremer, Meade, Graham, & 66
Dudgeon, 1998), an effect often thought to be caused by increased arousal during the 67
recovery period (Lambourne & Tomporowski, 2010). Many of the general population 68
exercise regularly for these additional health benefits instead of, or in addition to, physical 69
performance enhancement. It has been found that consuming CHO during exercise can 70
enhance these cognitive (Ali & Williams, 2009; Collardeau, Brisswalter, Vercruyssen, 71
Audiffren, & Goubault, 2001) and mood (Lieberman, Falco, & Slade, 2002) effects 72
demonstrating an interaction between nutritional state and exercise on post-exercise cognitive 73
performance. 74
The timing of exercise likely influences pre-exercise nutritional intake. When exercise is 75
undertaken in the morning, it is perhaps more common to remain fasted due to lack of time. 76
Some individuals may choose to exercise in a fasted state due to the associated increase in fat 77
oxidation (Backhouse, Williams, Stevenson, & Nute, 2007; Gonzalez, Veasey, Rumbold, & 78
Stevenson, 2013). Although this may be beneficial if weight loss is a main goal of exercise, 79
if breakfast is ommitted to achieve this, dietary guidelines which state that breakfast 80
consumption is important for health and wellbeing are contradicted (NIfHaC, 2006). The 81
positive health benefits of consuming breakfast include mood enhancement (Kral, Heo, 82
Whiteford, & Faith, 2012) and improvement in some aspects of cognitive performance, in 83
particular, memory [for review see (Marangoni, et al., 2009)]. These benefits have been 84
attributed to its timing, consumed first thing in the morning, breaking the overnight fast and it 85
is thought that breakfast may be vital for optimum cognitive function at this point (Benton & 86
Parker, 1998; Pollitt & Mathews, 1998). Although the acute mood-enhancing effects of 87
breakfast do tend to diminish after a few hours (Smith, Clark, & Gallagher, 1999), consuming 88
a mid-morning snack has been shown to improve declining mood following a large breakfast 89
(Benton, Slater, & Donohoe, 2001). Even if guidelines for exercise recovery are followed and 90
energy is replaced immediately following exercise [for example, by consuming chocolate 91
milk (Karp, et al., 2006; Thomas K, 2009)], omitting breakfast and inducing a further energy 92
deficit through exercise following an overnight fast may have detrimental cognitive and 93
mood effects later in the day. 94
Trials which have investigated the effect of consuming or omitting breakfast prior to exercise 95
on cognitive performance and mood are uncommon in the literature and have produced 96
diverse results (Hill, Whitehead, & Goodwin, 2011; Paul, Rokusek, Dykstra, Boileau, & 97
Layman, 1996; Vermorel, Bitar, Vernet, Verdier, & Coudert, 2003). In a cross-sectional 98
study by Vermoral et al. (2003), it was suggested that when adolescents have a morning 99
physical education lesson they require a substantial breakfast for cognitive benefits later in 100
the day (Vermorel, et al., 2003). Recently, there was no difference identified in the mood 101
state of swimmers who either consumed or omitted CHO before a morning training session 102
(Hill, et al., 2011) although Paul et al. (1996) reported an increase in mental fatigue during 103
the recovery period following a 90min cycle if breakfast was omitted rather than consumed 104
beforehand, but found no effect on cognition. However, no study to date has looked at the 105
interactive effect of breakfast consumption or omission prior to exercise or rest on cognitive 106
performance and mood in the same sample, which may be an important factor (Hubert, King, 107
& Blundell, 1998). Therefore the focus of the present paper was to assess the effect of 108
breakfast consumption and breakfast omission prior to rest or exercise, followed by a post-109
exercise recovery drink to assess cognitive performance and mood response. It was 110
hypothesized that consuming breakfast prior to exercise would elicit the most beneficial 111
cognitive performance and mood effects following a morning run. 112
Methods 113
Initial screening/Preliminary measurements 114
Ethical approval for the study protocol was granted by the Ethics Committee from the School 115
of Life Sciences at Northumbria University. Prior to participation volunteers gave written 116
informed consent. All participants confirmed that they were non-smokers, in good health and 117
free from social drugs, medication and herbal and dietary supplements at an initial screening 118
visit. Participants had no history of, or current, head trauma, learning difficulties, attention 119
deficit hyperactivity disorder (ADHD), dyslexia, migraines or gastric problems, a good 120
standard of English, equivalent to that of a native English speaker and were not high caffeine 121
consumers (<600mg per day). A further criterion for inclusion in the study was that 122
participants were at least moderately physically active, exercising for at least 30 minutes 5 123
times per week (confirmed using the International Physical Activity Questionnaire 124
[IPAQ;(Craig, et al., 2003)] and were able to run for 1h continuously. 125
Screening also comprised the collection of demographic information and training and 126
familiarisation with the cognitive tasks and experimental procedures. The battery of 127
cognitive tasks was repeated 3 times during this session to decrease the chance of learning 128
effects during main trials. Participants undertook two preliminary tests to establish 1) the 129
relationship between V˙ O2 and running speed on a flat treadmill using a 16-min test, and 2) 130
their V˙ O2max using an incremental treadmill test whereby the gradient was increased by 131
1%⋅min-1
to exhaustion as previously described in full detail (Williams, Nute, Broadbank, & 132
Vinall, 1990). The running speed equivalent to 60% of each participant‟s V˙ O2max was then 133
determined and the duration of exercise needed at this intensity to expend 2.9MJ was 134
calculated for each individual. The within subjects design with matched energy expenditure 135
during exercise intended to eradicate any significant effects that varying exercise durations 136
may have had on the results. On the day preceding the first trial, participants were required 137
to keep a record of their food intake and physical activity which was replicated the day 138
preceding subsequent trials. All 12 participants who attended the screening visit also 139
successfully completed the study. 140
Participants 141
Twelve, healthy, active men participated in the study. Their mean ± SD age, height, body 142
mass (BM), Body Mass Index (BMI) and maximal oxygen uptake (V˙ O2max) were 23.2 ± 143
2.4 y, 177.6 ± 7.0 cm, 77.2 ± 5.3 kg, 24.5 ± 2.0 kg/m2 and 50.7 ± 1.2 mL · kg
_1 · min
_1, 144
respectively. Participants abstained from alcohol and vigorous exercise for 24 h and fasted 145
for 12 h, prior to the start of each trial. 146
Cognitive and Mood Measures 147
The cognitive tasks and mood measures selected had shown previous sensitivity to nutritional 148
and/or exercise interventions. All tasks and visual analogue scales were administered using 149
the Computerised Mental Performance Assessment System (COMPASS, Northumbria 150
University), a programme used to present computerized standard psychometric tests. 151
COMPASS has been used in several previous nutritional intervention studies and has been 152
shown to be sensitive to acute cognitive enhancement and impairment with a variety of 153
substances [e.g. (Haskell, Kennedy, Wesnes, & Scholey, 2005; Jackson, Deary, Reay, 154
Scholey, & Kennedy, 2012; D. Kennedy, et al., 2010; D. O. Kennedy, et al., 2011; Scholey, 155
et al., 2010; Wightman, Haskell, Forster, Veasey, & Kennedy, 2012)]. Presentation of tasks 156
and mood scales was via a laptop computer. All responses were recorded via a button 157
response box (comprising buttons for Yes/No, Left/Right, Blue/ Green/Yellow /Red and a 158
central reaction time button). Each set of tasks took approximately 13 min to complete. 159
Participants were tested individually and were required to wear ear defenders throughout the 160
cognitive tasks to minimise noise distraction. 161
Simple Reaction Time (SRT; ~90 sec) 162
An arrow pointing upwards appeared in the centre of the computer screen at irregular 163
intervals (between 1 and 3.5 sec). The participant was instructed to press the centre button on 164
the response pad when the arrow appeared, responding as quickly and as accurately as 165
possible. The task was scored for overall reaction time (RT) to 30 stimuli. 166
167
Stroop task (~2 min) 168
Words describing one of four colours („RED‟, „YELLOW‟, „GREEN‟, „BLUE‟) were 169
presented in different coloured fonts in the centre of the computer screen. The participant 170
pressed one of four coloured response buttons in order to identify the font colour (e.g., if the 171
word „GREEN‟ was presented in a blue font, the correct response would be to respond with 172
the blue button). The presented words were either „congruent‟ (word and font are the same 173
colour) or „incongruent‟ (word and font are different colours) and were presented in a random 174
order. In total, 120 words were presented. The task was scored for RT and accuracy of 175
responses to „congruent‟ and „incongruent‟ words. 176
Four Choice Reaction Time (FCRT; ~90 sec) 177
Four direction arrow keys were displayed on the computer screen. The arrows „lit up‟ at 178
irregular intervals (between 1 and 3.5 sec), one at a time. Participants were instructed to use 179
the index finger of their dominant hand to press the corresponding button on the response pad 180
(left/right/up/down) when an arrow became lit, responding as quickly and as accurately as 181
possible. In total, 32 stimuli were presented. The task was scored for RT and accuracy of 182
responses. 183
N-Back (~2 min) 184
A series of single letters appeared on the screen, presented one at a time. If the letter that 185
appeared was also presented 3 letters previously in the series, participants were asked to press 186
the „YES‟ button on the response pad and if the letter that appeared was not presented 3 187
letters previously in the series, to press the „NO‟ button on the response pad, responding as 188
quickly and accurately as possible to every letter presented. In total, 36 stimuli were 189
presented, encompassing 12 target pairs. The task was scored for RT and accuracy. 190
Rapid visual information processing task (RVIP; 5 min) 191
A series of single digit numbers between 1 and 9 appeared on the screen continuously at a 192
rate of 100 per min-1
for 5 minutes. Participants were required to use the index finger of their 193
dominant hand to press the centre button on the response box, reacting as quickly and 194
accurately as possible, when they identified three odd or even digits presented in succession. 195
Eight correct target strings were presented each minute. The task was scored for percentage 196
of target strings correctly detected, average RT for correct detections and number of false 197
alarms. 198
Mental Fatigue and Task Difficulty Visual Analogue Scales 199
Two single visual analogue scales measuring mental fatigue and task difficulty were 200
completed at the end of each set of tasks. Each scale was labelled “not at all” (left end of 201
scale) and “extremely” (right end of scale). 202
Mood and Physical State Visual Analogue Scales 203
A set of mood and physical state visual analogue scales [adapted from (Rogers, Richardson, 204
& Elliman, 1995)] were completed before each set of cognitive tasks measuring subjective 205
ratings of mood and physical state (“relaxed,” “alert,” “jittery,” “tired,” “tense,” “headache, ” 206
“overall mood”). Participants were asked to click on a 100mm line on the computer screen to 207
grade their current subjective status for each state. Each scale was labelled “not at all” (left 208
end of scale) and “extremely” (right end of scale), except for “overall mood” which was 209
labelled “very bad” and “very good”. During exercise trials, participants also completed a 210
single VAS immediately following the exercise session rating to what extent they enjoyed the 211
run. 212
All VAS scales were scored as mm along the line towards „extremely‟. 213
Treatments/Test meals 214
The nutritional content of the breakfast, snack and lunch provided in the study are detailed in 215
Table 1. Participants were given a maximum of 15 min to consume the breakfast. The post-216
exercise/rest snack was served at room temperature and participants were instructed to finish 217
the drink within 5 min. Participants confirmed verbally that the drink was well liked. 218
Each portion of the ad libitum lunch was prepared in advance and re-heated in the microwave 219
for 2.5 minutes as required. 220
Procedure/ Experimental protocol (Fig. 1) 221
Each participant completed four trials, in a randomised, cross-over design, consisting no 222
breakfast and rest (NB NE), breakfast and rest (B NE), no breakfast and exercise (NB E) or 223
breakfast and exercise (B E). The first trial was undertaken between 48 h and 14 days of the 224
initial screening visit. Trials were separated by ≥48 hours and all trials were performed under 225
similar laboratory conditions. Trials began at 0730 h (±15 min). After confirming 226
compliance to the study restrictions, a baseline completion of the cognitive tasks and mood 227
scales was then undertaken, before participants were administered the test breakfast or 228
remained fasted. During the 2 h rest period which followed, cognitive performance and 229
mood were measured at 60 and 120 min. In between these periods, participants were allowed 230
to read, write or watch a DVD. In the exercise trials (NB E and B E), participants then 231
completed a treadmill run at 60% of their V˙ O2, until 2.9MJ had been expended with heart 232
rate and rate of perceived exertion (RPE) measured at 10 min intervals throughout. Exercise 233
intensity was maintained throughout this period via an online gas analysis system (Metalyzer 234
3B, 164 Cortex, Germany). On rest days (NB NE and B NE), participants rested for the 235
equivalent amount of time. Cognitive performance and mood were reassessed before 236
participants were administered a test drink, followed by a 90 min rest period where cognitive 237
performance and mood was assessed at 30 and 75 min. This was followed by an ad libitum 238
lunch where participants were asked to consume enough food to feel satisfied to a normal 239
level. After lunch, they completed the cognitive tasks and mood scales for a final time and 240
were then free to leave the laboratory. Heart rate was monitored throughout each trial using 241
telemetry (Polar T31 transmitter, Polar Electro Oy, HQ, Professorintie 5, FIN-90440 242
Kempele, Finland). Water intake was recorded during each first rest trial and first exercise 243
trial and was approximately matched in the subsequent rest and exercise trials. 244
245
2.8 Statistical Analysis 246
Data was split into three distinct parts for analysis: Post-breakfast (assessing the effects of 247
breakfast consumption vs. breakfast omission only), during and/or immediately post-248
exercise/rest (to assess the immediate interaction between the breakfast and exercise 249
interventions) and from post drink (to assess the cognitive responses to the test drink). For 250
each analysis, change values from the same baseline were used. 251
Cognitive task repetition was used to calculate sample size. Based on the 4 repetitions 252
completed after both interventions had taken place, a power calculation revealed that a 253
sample size of 12 would provide statistical power to detect large effects above 80% with an 254
alpha level of .05 (Faul, Erdfelder, Lang, & Buchner, 2007). Before the main statistical 255
analysis, paired sample t tests were used to compare pre-dose baseline data to assess for 256
differences in performance across the study days. Scores for each individual task outcome 257
(SRT, Stroop, FCRT, N-back, RVIP, mental fatigue VAS, difficulty VAS and mood and 258
physical state VAS) were analysed as „change from baseline‟ using Minitab 16 (Minitab Ltd, 259
Coventry, UK). Separate analysis was conducted for data collected pre-exercise/rest (two-260
way repeated measures AVOVA, breakfast (NB = 0, B = 1) x repetition) and during and post 261
exercise/rest (two-way repeated measures ANOVA [repetition × breakfast (NB = 0, B = 262
1)×exercise(NE = 0, E = 1)]) and post-drink (two-way repeated measures ANOVA [repetition 263
× breakfast (NB = 0, B = 1)×exercise(NE = 0, E = 1)]). The latter analysis also allowed the 264
detection of any main effects of breakfast (irrespective of exercise) and of exercise 265
(irrespective of breakfast). Planned comparisons (using t tests calculated with the Mean 266
Squares Error) were then employed to show where the significance lay in significant 267
interactions shown by the ANOVA, which were corrected using Bonferroni where 268
appropriate. An alpha level of .05 was used for all statistical tests. Means ± Standard Error 269
Mean are reported for significant findings. 270
Results 271
There were no significant differences between mean baseline scores for any of the treatment 272
conditions or outcome measures. Significant main effects and interactions for COMPASS 273
tasks, mood and physical state VAS are reported below. Due to a data capture error only 11 274
participants were included in the N-back and Stroop analysis and 9 in the RVIP analysis. 275
Post-breakfast Analysis 276
No effects on cognitive performance or mood were observed during the 2h post-breakfast 277
period. 278
Post-exercise/Rest Analysis 279
No cognitive performance or mood variable effects were observed immediately following the 280
exercise or rest period. 281
Post-drink Analysis 282
Cognitive Performance 283
No effects were observed for the simple reaction time or N-back tasks or task difficulty. 284
Four Choice Reaction Time 285
No interactions between breakfast and exercise were observed for this task. A main effect of 286
breakfast on FCRT accuracy was observed [F (1, 10) = 5.04, p = .046] with a lower 287
percentage of correct responses seen when breakfast was consumed (-0.4 ± 0.4%) compared 288
to omitted (1.1 ± 0.5%; Fig. 2). 289
Stroop 290
A significant exercise x breakfast interaction was observed for Stroop task accuracy [F (1, 291
7)=7.84, p = .019]. Comparisons revealed poorer accuracy in the B NE condition (-0.4 ± 292
0.6%) compared to the B E condition (0.6 ± 0.6 %; t(10) = 3.96, p = .001) the NB E condition 293
(-0.4 ± 0.5%; t(10) = 3.13, p = .013) and the NB NE condition (1.5 ± 0.5%, t(10) = 4.71, p < 294
.001; Fig. 3a). 295
296
Rapid Visual Information Processing task 297
A significant exercise x breakfast interaction was observed for the RVIP task [F (1, 5)=10.74, 298
p = .011]. Comparisons revealed a quicker RT in the NB NE condition (-14.6 ± 6.5ms) than 299
in the B NE condition (25.8 ± 9.1ms; t(8) = 3.23, p = .010; Fig. 3b). 300
301
Mental fatigue ratings 302
A significant breakfast x exercise interaction was seen [F (1, 8) = 11.89, p = .005] with 303
significantly higher mental fatigue ratings reported in the NB E condition (25.9 ± 2.7mm) 304
compared to the NB NE (10.9 ± 2.9; t(11) = 3.60, p = .003) and B E condition ( 11.1 ± 305
2.6mm; t(11) = 3.55, p = .003; Fig. 3c). 306
307
Mood and Physical State VAS 308
No significant effects of breakfast or exercise on ratings of relaxation, alertness, jitteriness, 309
tiredness or overall mood were observed. 310
Tension ratings 311
A breakfast x exercise interaction was found for ratings of tension [F (1, 8) = 9.75, p = .010]. 312
Tension was significantly higher in the B NE (3.8 ± 2.9mm) and NB E (5.8 ± 2.5mm; t(11) = 313
3.13, p = .013) conditions compared to the NB NE condition (-12.5 ± 2.1; t(11) = 2.79, p = 314
.036; Fig. 3d). 315
316
Heart rate, RPE and Exercise Enjoyment VAS 317
There were no significant differences observed for RPE or enjoyment VAS ratings during the 318
exercise trials. Due to a large amount of missing data points, data for heart rate was not 319
analysed. 320
Discussion 321
This study investigated the effects of breakfast consumption or omission prior to exercise or 322
rest on cognitive performance and mood in healthy, habitually active males. The results 323
suggest that breakfast consumption and exercise interact to influence some aspects of 324
cognitive performance and mood. 325
Significant effects were only observed following consumption of the drink. Breakfast had a 326
negative impact on Four Choice Reaction Time (FCRT) accuracy, irrespective of exercise 327
intervention. Consumption of breakfast, as opposed to fasting, prior to rest also reduced speed 328
of Rapid Visual Information Processing (RVIP) and Stroop task accuracy, with exercise or 329
omitting breakfast reversing the latter effect. Breakfast omission prior to exercise led to 330
significantly higher mental fatigue ratings than breakfast omission prior to rest or breakfast 331
consumption prior to exercise. An increase in tension was also seen when exercise was 332
undertaken in a fasted state and when breakfast was consumed followed by rest, as compared 333
to no breakfast followed by rest. 334
The findings of decrements to performance following breakfast may seem surprising in light 335
of research demonstrating a positive effect of breakfast [for review see (Hoyland, Lawton, & 336
Dye, 2008)] . However, the majority of positive effects of breakfast have been shown on tests 337
of delayed verbal memory. Reaction time is often reported to decrease with increased feelings 338
of hunger (Fischer, Colombani, & Wenk, 2004), and impairment in concentration following a 339
high caloric breakfast has also been reported (Michaud, Musse, Nicolas, & Mejean, 1991). It 340
is important to note that decrements following breakfast were only demonstrated when 341
measured at least 3 hours later and following consumption of a chocolate drink. It is possible 342
that these detrimental findings in the current study reflect a positive effect of the drink only 343
observed when breakfast has not been consumed, or a negative outcome of the interaction 344
between breakfast and the drink. 345
Paul et al., (1996) failed to find any effect of breakfast consumption prior to cycling on 346
cognitive performance, whereas in the current study negative effects of breakfast on RVIP 347
reaction time and Stroop accuracy were eradicated by combining with an exercise bout. 348
The literature does suggest that exercise is stimulating (Lambourne & Tomporowski, 2010) 349
and an increase in arousal post-exercise can decrease RT (Etnier, et al., 1997) and facilitate 350
the speed of decision making (Adam, et al., 1997; McMorris & Graydon, 1996). Similarly, 351
higher tension ratings reported in the current study when exercise was undertaken, or 352
breakfast was consumed, in isolation were eradicated by combining breakfast consumption 353
and exercise. In line with the current finding of mitigation of mental fatigue through the 354
consumption of breakfast prior to exercising, Paul et al., (1996) previously reported lower 355
ratings of post-exercise central fatigue following breakfast consumption, rather than 356
omission, prior to cycling (Paul, et al., 1996). The authors suggested that the protein in the 357
breakfast likely attenuated an exercise-induced rise in brain serotonin, a neurotransmitter 358
known to increase fatigue sensitivity (Newsholme E.A., Acworth, & Blomstrand, 1987), 359
although physical fatigue during exercise measured using RPE was not affected by prior 360
breakfast consumption, a finding replicated in the current study. In addition, brain 361
requirements for fuel (i.e. glucose) may be high during the post-exercise recovery period (Ide, 362
Horn, & Secher, 1999); if fuel availability is poor, this could be detrimental for mood 363
(Benton & Parker, 1998; Pollitt & Mathews, 1998). Consuming a high CHO meal prior to 364
exercise may reduce this effect by increasing pre-exercise glycogen stores (Hargreaves, 365
Hawley, & Jeukendrup, 2004). These results suggest that consuming breakfast before 366
exercise is beneficial for post-exercise mental state, supporting the original hypothesis. 367
However, it has also been previously reported that breakfast consumption or omission prior to 368
swimming does not alter post-exercise mood (Hill, et al., 2011), suggesting that exercise 369
mode can influence how pre-exercise nutritional state alters post-exercise mood. 370
371
It is important to note that whilst the majority of participants in this study were habitual 372
breakfast consumers, four participants (25%) did not consume breakfast often enough to be 373
classed as habitual consumers. Although there is some evidence to suggest that long-term 374
breakfast habits may influence response to acute breakfast consumption (Halsey, et al., 2012; 375
Pereira, et al., 2011), given that consuming breakfast prior to exercise was not a completely 376
novel situation for any of the participants, it is unlikely this would have significantly 377
influenced the results. Another caveat in the current study was that tolerance to the 378
nutritional interventions was not measured. Although participants confirmed verbally that the 379
test drink and pasta lunch were well liked, some participants did not find the test breakfast 380
pleasant to eat. Findings showing that consuming breakfast which is different in composition 381
from that which is normally consumed can negatively affect mood (Lluch, Hubert, King, & 382
Blundell, 2000) may explain the detrimental impact of breakfast in the current study. 383
Information on the habitual morning exercise routine of this sample would have also been 384
beneficial when assessing the effect of the chosen interventions. 385
Currently, this data only extends to males. Conducting a similar study using a female 386
population, who are generally under-represented in the literature, would add to knowledge in 387
this research area. 388
This is believed to be the first study to establish the effect of consuming or omitting a 389
breakfast meal prior to exercise or rest on cognitive performance and mood. The results 390
suggest that in habitually active males, poorer pre-exercise nutritional state can negatively 391
influence mood state post-exercise after a post-exercise snack. Also, breakfast can adversely 392
affect cognitive performance, an effect reversed by undertaking exercise. 393
394
Acknowledgements 395
This study was completed as part of the PhD of R.C.V., funded by Northumbria University. 396
Data collection was conducted by R.C.V and J.G. All authors contributed to the study design 397
and to the writing of the manuscript. All authors read and approved the final manuscript. The 398
authors declare that they have no conflicts of interest. 399
400
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Figure Legends 528
Fig. 1. Study Schematic 529
Fig. 2. The effect of breakfast consumption or omission (B or NB) on Four Choice Reaction 530 Time accuracy following a mixed-macronutrient drink in active males. Values are change 531
from baseline ± SEM, (n = 12, *p<.05) 532
Fig. 3. The effects of prior breakfast consumption or omission (B or NB) and exercise or rest 533
(E or NE) on (a) Stroop accuracy (n = 11), (b) Rapid Visual Information Processing task 534 reaction time (n = 9), (c) mental fatigue (n = 12) and (d) tension (n = 12) following a mixed-535 macronutrient drink in active males. Values are change from baseline ± SEM, (*p<.05; 536
**p<.01; *** p<.001) 537
538
Table 1. Nutritional content of study foods
kJ/Kcal
Carbohydrate
(g)
Protein
(g)
Fat
(g)
Fibre
(g)
Breakfast
72g Syrup flavour porridge
oats 1129/271 48 6 5 6
360ml Semi-skimmed milk 752/180 17 13 7 0
Total 2560/451 65 19 18 6
Snack
250ml Chocolate milk 713/175 25 8 4 2
Lunch
125g Penne Pasta 1863/444 90 15 2 1
250g Bolognase pasta sauce 440/110 15 2 4 6
15g Oilve Oil 555/135 0 0 15 0
40g Cheddar Cheese 686/249 Trace 10 14 0
Total 3544/938 105 27 35 7
539
Fig. 1 540
541
542
Fig. 2 543
544
545
Fig. 3 546
547
548
549
This study examined the interaction between breakfast and exercise in active males
When breakfast was ommitted, post-exercise mental fatigue increased
Where breakfast inhibited cognitive function, exercise reversed this effect
Breakfast consumption prior to exercise may benefit mood