Exercise-cognition interaction : neuroscience perspectives

489 Pages·2016·10.871 MB·English

by  McMorris, Terry

EXERCISE–
COGNITION
INTERACTION

NEUROSCIENCE PERSPECTIVES
T M M
erry c orris
Department of Sport and Exercise Science, University of
Chichester, Chichester, West Sussex, UK
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Contributors
Lori J.P. Altmann Department of Speech, Language Jo Corbett Department of Sport and Exercise
and Hearing Sciences, University of Florida, Gaines- Science, Faculty of Science, University of Ports-
ville, FL, USA mouth, Portsmouth, UK
Soichi Ando Graduate School of Informatics and Flávia Gomes de Melo Coelho Institute of Biosci-
Engineering, University of Electro-Communications, ences, UNESP, Univ. Estadual Paulista, Physi-
Chofu, Tokyo, Japan cal Activity and Aging Lab (LAFE), Rio Claro,
Michel Audiffren Research Institute on Cogni- São Paulo, Brazil; Department of Sports Sciences,
tion and Learning (UMR CNRS 7295), Sport Sci- UFTM, Univ. Federal do Triângulo Mineiro, Ubera-
ences Faculty, University of Poitiers, Poitiers, ba, Minas Gerais, Brazil
France Catherine L. Davis Georgia Prevention Institute, Med-
Anne-Claude V. Bédard Department of Applied ical College of Georgia, Department of Pediatrics,
Psychology and Human Development, Ontario In- Georgia Regents University, Augusta, GA, USA
stitute for Studies in Education, University of To- Jennifer L. Etnier Department of Kinesiology,
ronto, Toronto, Ontario, Canada University of North Carolina at Greensboro,
Tal Dotan Ben-Soussan Research Institute for Greensboro, NC, USA
Neuroscience, Education and Didactics, Patrizio Sebastião Gobbi Institute of Biosciences, UNESP,
Paoletti Foundation for Development and Com- Univ. Estadual Paulista, Physical Activity and
munication, Assisi, Italy; Bar-Ilan University, Ra- Aging Lab (LAFE), Rio Claro, São Paulo, Brazil
mat-Gan, Israel
Ben Godde Jacobs Center on Lifelong Learning
Olga G. Berwid Department of Behavioral Sciences, and Institutional Development, Jacobs University,
York College of the City University of New York, Bremen, Germany
Jamaica, NY, USA
John Gunstad Department of Psychological Sciences,
Dawn Bowers Department of Clinical & Health
Kent State University, Kent, OH, USA
Psychology, University of Florida, Gainesville,
FL, USA Madeleine E. Hackney Atlanta VA Center for
Visual and Neurocognitive Rehabilitation, Division
Henning Budde Medical School Hamburg, Fac-
of General Medicine and Geriatrics, Department of
ulty of Human Sciences, Department of Pedagogy,
Medicine, Emory University School of Medicine,
Hamburg, Germany; Reykjavik University, School
Decatur, GA, USA
of Science and Engineering, Department of Sport
Science, Reykjavik, Iceland Beverley J. Hale Department of Sport and Exercise
Science, University of Chichester, Chichester, West
Eduardo E. Bustamante Georgia Prevention Insti-
Sussex, UK
tute, Medical College of Georgia, Department of
Pediatrics, Georgia Regents University, Augusta, G.F. Hamilton Department of Psychology, The
GA, USA Beckman Institute, University of Illinois at Urbana-
Yu-Kai Chang Graduate Institute of Athletics Champaign, Urbana, IL, USA
and Coaching Science, National Taiwan Sport Chris J. Hass Department of Applied Physiology
University, Guishan Township, Taoyuan County, and Kinesiology, University of Florida, Gainesville,
Taiwan (R.O.C.) FL, USA
ix
x
CONTRIBUTORS
Keita Kamijo Faculty of Sport Sciences, Wase- Caterina Pesce Department of Movement, Human
da University, Mikajima, Tokorozawa, Saitama, and Health Sciences, Italian University Sport and
Japan Movement “Foro Italico”, Rome, Italy
Flora Koutsandréou Medical School Hamburg, Fac- Aaron T. Piepmeier Department of Kinesiol-
ulty of Human Sciences, Department of Pedagogy, ogy, University of North Carolina at Greensboro,
Hamburg, Germany; University of Bern, Institute Greensboro, NC, USA
of Sport Science, Bern, Switzerland J.S. Rhodes Department of Psychology, The Beckman
Cynthia E. Krafft MIND Institute, Department of Institute, University of Illinois at Urbana-Champaign,
Psychiatry and Behavioral Sciences, University of Urbana, IL, USA
California Davis, Sacramento, CA, USA Ruth Ferreira Santos-Galduróz Institute of Biosci-
Jesper Krogh Department of Medicine, Center of ences, UNESP, Univ. Estadual Paulista, Physical
Endocrinology and Metabolism, Copenhagen Uni- Activity and Aging Lab (LAFE), Rio Claro, São
versity Hospital Herlev, Herlev, Denmark Paulo, Brazil; Center of Mathematics, Computing
Michael J. Mackenzie Department of Behavioral and Cognition, UFABC, Univ. Federal of ABC, Santo
Health & Nutrition, University of Delaware, New- André, São Paulo, Brazil
ark, DE, USA David J. Schaeffer Department of Neuroscience,
Edward McAuley Department of Kinesiology & University of Georgia, Athens, GA, USA
Community Health, University of Illinois at Urbana- Chia-Hao Shih Department of Kinesiology, Univer-
Champaign, Urbana, IL, USA sity of North Carolina at Greensboro, Greensboro,
Jennifer E. McDowell Department of Neuroscience, NC, USA
University of Georgia, Athens, GA, USA John Sproule Institute of Sport, PE and Health Sci-
Terry McMorris Department of Sport and Exercise ences, University of Edinburgh, Edinburgh, Scot-
Science, University of Chichester, Chichester, West land, UK
Sussex, UK Anthony Turner Institute of Sport, PE and Health
Lindsay Miller Department of Psychiatry and Hu- Sciences, University of Edinburgh, Edinburgh,
man Behavior, Warren Alpert Medical School of Scotland, UK
Brown University, Providence, RI, USA Thays Martins Vital Institute of Biosciences, UN-
Claudia Niemann Institute of Human Move- ESP, Univ. Estadual Paulista, Physical Activity and
ment Science and Health, Technische Universitaet Aging Lab (LAFE), Rio Claro, São Paulo, Brazil;
Chemnitz, Chemnitz, Germany; Jacobs Center on Instituto Federal Goiano - Campus Morrinhos,
Lifelong Learning and Institutional Development, Morrinhos, GO, Brazil
Jacobs University, Bremen, Germany Claudia Voelcker-Rehage Institute of Human
Joe R. Nocera Atlanta VA Center for Visual and Movement Science and Health, Technische Uni-
Neurocognitive Rehabilitation, Department of versitaet Chemnitz, Chemnitz, Germany; Jacobs
Neurology, Emory University School of Medi- Center on Lifelong Learning and Institutional
cine, Decatur, GA, USA Development, Jacobs University, Bremen, Germany
Sarah C. O’Neill Department of Psychology, City Michelle W. Voss Department of Psychological
College of the City University of New York, New and Brain Sciences, Aging Mind and Brain Initia-
York, NY, USA; Department of Psychology, Gradu- tive (AMBI), The University of Iowa, Iowa City,
ate Center of the City University of New York, New IA, USA
York, NY, USA Mirko Wegner University of Bern, Institute of Sport
Maria Pedersen Department of Clinical Physiology Science, Bern, Switzerland
and Nuclear Medicine, Copenhagen University Krystle E. Zuniga Nutrition & Foods, Texas State
Hospital Herlev, Herlev, Denmark University, San Marcos, TX, USA
C H A P T E R
1
History of Research into the Acute
Exercise–Cognition Interaction:
A Cognitive Psychology Approach
Terry McMorris
Department of Sport and Exercise Science, University of Chichester, Chichester, West Sussex, UK
INTRODUCTION
a theoretical underpinning for hypothesiz-
ing that acute exercise would have an effect
In this chapter, we examine the develop- on cognition was Davey (1973). He saw exercise
ment of theoretical underpinnings for an acute as being a stressor, which could affect arousal in
exercise effect on cognition, from the earliest the same way as other stressors, such as anxiety,
research until the emergence of recent neurosci- temperature, and white noise. Davey, therefore,
entific research. We also examine the extent to turned to Yerkes and Dodson’s (1908) arousal–
which empirical research supported the behav- performance theory to develop his hypotheses.
ioral and cognitive rationales and how failure Yerkes and Dodson claimed that when arousal
to provide strong support led to a revision of is low, performance will be poor but, as arousal
these theoretical underpinnings. The overall aim rises to a moderate level, performance will
of writing this chapter is to provide the reader become optimal. However, if arousal continues
with an outline of the background of theory and to rise, performance will return to a level equal
research, which has led to the current study of to that shown during low levels of arousal.
the acute exercise–cognition interaction from a When plotted graphically, performance dem-
neuroscientific perspective. onstrates an inverted-U curve and, as a result,
Yerkes and Dodson’s theory became known
as inverted-U theory. Based on this, Davey
Development of Theoretical Rationales
claimed that at rest and during low-intensity
The earliest research was atheoretical (e.g., exercise, cognitive performance would be poor.
Gutin & Di Gennaro, 1968a; McAdam & Wang, When exercise intensity rose to a moderate
1967; Meyers, Zimmerli, Farr, & Baschnagel, 1969). level, performance would be optimal, but fur-
It appears to have simply been down to the ther increases in exercise intensity would mean
whims of the researchers. The first to provide a return to a poor level of performance.
Exercise-Cognition Interaction
1
http://dx.doi.org/10.1016/B978-0-12-800778-5.00001-3 © 2016 Elsevier Inc. All rights reserved.
2
1. A COGNITIVE PSYCHOLOGY APPROACH
Yerkes and Dodson (1908) showed empiri- Delignières, Brisswalter, & Legros, 1994) and later
cally, with mice, that task complexity acted as ourselves (McMorris & Graydon, 1996a, 1996b,
a moderator with regard to the purity of the 1997; McMorris & Keen, 1994) turned to what
inverted-U curve. They found that if a task was some call allocatable resources theories but others
easy, the curve was skewed toward the higher call cognitive–energetical theories (Kahneman,
end of the arousal continuum, but if the task 1973; Sanders, 1983). These theories still predict
was complex, it was skewed the other way. In an inverted-U effect on performance but the theo-
other words, easy tasks require comparatively ries are multidimensional and as such are better
high levels of arousal for optimal performance, able to explain interactions between the stressor
whereas complex tasks require comparatively and the task.
low levels of arousal. Kahneman (1973) believed that individu-
Inverted-U theory continues to play a major als have a limited amount of resources. The
role as an underlying theory with regard to amount is not fixed but flexible. He claimed that
acute exercise–cognition research, but most cog- as arousal rises, the number of resources avail-
nitive psychologists also include adaptations of able, within the brain, increases. Like Yerkes and
Yerkes and Dodson’s (1908) theory. Several (e.g., Dodson, he argued that this increase is benefi-
Allard, Brawley, Deakin, & Elliott, 1989; Fleury, cial for performance up to a certain point, after
Bard, & Carrière, 1981; Isaacs & Pohlman, 1991) which there will be a return to baseline levels. It
have drawn on Easterbrook’s (1959) cue utili- is here that Kahneman disagrees with Yerkes and
zation theory. Easterbrook felt that Yerkes and Dodson. To Kahneman, increases in arousal are
Dodson’s theory failed to provide a rationale not the only factor affecting performance. The
for how arousal would affect performance in increase in the number of resources, as arousal
an inverted-U fashion. Following a number of increases to a moderate level, will only result in
experiments into effects of arousal on dual task improvements in performance if the person allo-
performance, Easterbrook claimed that increases cates the resources to the task in hand.
in arousal from low to high levels results in a The allocation of resources to task relevant
narrowing of focus of attention. He stated that information is said to be undertaken by cogni-
when arousal level is low, the individual has too tive effort (more often just referred to as effort)
broad an attentional focus and attends to both and depends on the individual’s allocation
relevant and irrelevant information; as a result policy. Kahneman believed that there are four
performance is poor. As arousal rises, however, factors affecting this policy, what he termed
attention reaches an optimal level, when only enduring dispositions, momentary intentions,
task relevant cues are processed. This corre- evaluation of task demands, and the effects of
sponds to the top of the inverted-U curve in Yer- arousal. Enduring dispositions are the rules of
kes and Dodson’s theory. If arousal continues to involuntary attention, e.g., familiar and novel
rise, however, attention will narrow further and stimuli will be attended to automatically.
even relevant cues will be missed, hence a dete- Momentary intentions refer to the instructions
rioration in performance. given to the individual for that particular task
Yerkes and Dodson’s (1908) and Easterbrook’s at that moment in time. Perhaps of greatest
(1959) theories remained the most popular importance is the evaluation of task demands.
theories for researchers to use as the theoreti- According to Kahneman, the person decides
cal underpinnings for their hypotheses until whether or not they have sufficient capacity, at
the 1990s. At this time, first the Poitiers group that moment, to be able to do what is required
(e.g., Arcelin, Delignières, & Brisswalter, 1998; of them. Finally, the effects of arousal refers to
Brisswalter, Arcelin, Audiffren, & Delignières, the available channel capacity at that moment
1997; Collardeau, Brisswalter, & Audiffren, 2001; in time.
InTRoduCTIon 3
Kahneman (1973) believed that during mod- Audiffren (2009) and Audiffren, Tompo-
erate levels of arousal, effort can easily allocate rowski, and Zagrodnik (2009) saw Hockey’s
resources to the task. This does not differ from (1997) cognitive–energetical theory, sometimes
Yerkes and Dodson (1908) or Easterbrook (1959); called compensatory control theory, as being
however, during high levels of arousal, Kahne- particularly useful in explaining the acute exer-
man believed that the individual would not be cise–cognition interaction. Hockey’s model is
able to allocate resources to the task. In these mostly concerned with how the individual per-
circumstances, evaluation of task demands will forms under stress. He claimed that we have
tend to lead to the perception that the task can- two performance regulation loops, the effort-
not be successfully completed, while enduring ful control loop and the automatic control loop.
dispositions may lead to the individual focusing The role of the automatic control mechanism,
on their feelings of distress or excitement. which functions without effort, is to undertake
Sanders (1983) took a similar approach to the regulation of well-learned skills. It includes
Kahneman (1973) but there were some differ- a mechanism called the action monitor, which
ences. Sanders argued that the different stages compares target outcomes with actual out-
of cognitive processing needed to be energized comes. If a discrepancy is detected, adjustments
by different energetical mechanisms. He termed in resource allocation are made. However, even
these arousal, activation, the evaluation mecha- with well-learned skills, when under stress task
nism, and effort. Arousal was seen as a readi- demands can affect performance. The role of the
ness to process input and activation as a motor effortful control loop is to maintain performance
readiness to respond. The role of the evaluation despite interference from stressors. Hockey saw
mechanism is to provide effort with information this loop as containing a mechanism similar
concerning performance outcome and, perhaps to that of Sanders’ evaluation mechanism,
more importantly, the physiological states of which he called the effort monitor mechanism.
the arousal and activation mechanisms. This is It is assumed to be sensitive to the demands
vital because effort is responsible for energizing placed on the automatic control mechanism and
response choice but also has the job of control- whether or not it is coping. This information
ling and coordinating arousal and activation. is passed to the supervisory controller, which
Sander’s model draws a great deal from the decides on the compensatory action to be taken
model proposed by Pribram and McGuinness in order to solve the problem. This can be by
(1975), which could be described as a cognitive increasing effort, if that is deemed possible, or
neuroscience model. by adjusting the individual’s goals downwards,
Pribram and McGuinness (1975), after examin- if the goal demands are perceived as being
ing the neuropsychological evidence for arousal, unobtainable.
decided that it was more accurate to divide what Although individual researchers differed in
Kahneman (1973) had called arousal into three their choice of theory or model, almost all fol-
distinct but interacting systems, which they lowed an inverted-U approach. Moreover, few
called arousal, activation, and effort. Arousal was voiced any objections to the notion that acute
defined as being “phasic physiological responses exercise is a stressor; therefore, it will affect cog-
to input” (p. 115), e.g., when a batter in baseball or nition in the same way as any other stressor.
cricket is facing a pitcher or bowler, their alertness My colleague Peter Keen and I (McMorris &
and attention increase. Activation was seen as “a Keen, 1994) did suggest caution when equat-
tonic physiological readiness to respond” (p. 115), ing exercise-induced arousal with emotionally
e.g., the batter readies her/himself to hit the ball. induced arousal. We argued that when physi-
Effort was described as the coordinating activity of ological changes are the result of exercise, they
the arousal and activation systems. “are induced and mediated by the activated
4
1. A COGNITIVE PSYCHOLOGY APPROACH
musculature and are responding to exercise Later, my colleague Jan Graydon and I (McMorris
load, i.e., attempting to maintain homeostasis. & Graydon, 1996b) questioned whether inverted-
Somatic arousal rising from emotions, however, U theory provided an effective underpinning for
is induced by the brain and destroys homeosta- hypotheses formation in acute exercise–cogni-
sis” (p. 129). We accepted that exercise is a stressor tion interaction studies. We claimed that drive
and were quite happy with the idea that moder- theory (Hull, 1943; Spence, 1958) might provide
ate intensity exercise would induce optimal per- a more valid rationale. According to drive theory,
formance but we were not convinced that heavy increases in arousal will result in an improvement
exercise would necessarily be perceived as being in performance if habit strength is high. If habit
distressful by the individual. Our argument was strength is low, increases in arousal will either
that someone with a heart rate of 180 bpm, who have no effect or will result in a breakdown in per-
was exercising maximally, was still in a state of formance. Hull and Spence asserted that the equa-
homeostasis. As long as the individual did not tion is further complicated by the incentive value
perceive the task demands as being beyond his/ of completing the task. They stated that there will
her capabilities, they would not demonstrate be an interaction between arousal, habit strength,
very high levels of arousal and therefore cogni- and incentive value. This interaction could be
tive performance may not return to a level equal explained by the formula, P = D × H × I, where P
to that during low-intensity exercise. is performance, D is drive or arousal, H is habit
Although we (McMorris & Keen, 1994) ques- strength, and I is incentive value. Habit strength
tioned equating even maximal intensity exercise refers to the level of automaticity of the skill. Given
with very high levels of emotionally induced this theory, performance of well-learned skills
arousal, we did believe that an inverted-U effect may actually improve as arousal rises. However,
would be demonstrated but it would possibly if habit strength is low, the profile might show no
need the individual to attempt to undertake supra- effect or demonstrate a deterioration at high levels
maximal intensity exercise for it to manifest itself. of arousal (see Figure 1).
FIGURE 1 Arousal–performance interaction according to drive theory.
InTRoduCTIon 5
McMorris and Graydon (1996b) also pointed a linear improvement in performance would be
to Douchamps’ (1988) theory of operational demonstrated. This is similar to Hull’s (1943)
performance as a possible theoretical underpin- claims for well-learned tasks (see Figure 1).
ning for an acute exercise–cognition interaction. Tasks that require holding information in short-
Douchamps claimed that arousal was tridimen- term memory would, however, be negatively
sional in nature and he argued that there are affected by high levels of arousal but not mod-
energetic, computational, and emotional dimen- erate levels. For these tasks, they hypothesized
sions. He believed that the central nervous sys- a deterioration during higher levels of arousal.
tem (CNS) gives priority to the dimension that is Tasks demanding both sustained information
most highly aroused at the expense of the other transfer and short-term memory could show
dimensions. According to Douchamps, energetic an inverted-U effect. The sustained information
arousal is a readiness to act physically and, there- transfer factor would be facilitated by increased
fore, only positively affects motor acts. Thus, arousal and on-task effort, so there would be an
acute exercise would have a negative effect on improvement in performance at moderate lev-
cognition. Douchamps’ argument is based on the els of arousal. However, during high levels of
notion of limited CNS resources; therefore, if one arousal, the negative effects on the short-term
dimension is allocated more resources, it must memory processes would be inhibited, thus
be at the expense of other dimensions. This has negating the positive effects on sustained infor-
similarities to reticular formation hypofrontality mation transfer. Hence, there would be a return
theory (Dietrich & Audiffren, 2011) (see Chapter to baseline levels of performance.
7). Douchamps’ theory is probably only relevant
Summary
when exercise is heavy, similar to transient hypo-
frontality theory (Dietrich, 2003), the forerunner All of the theories were devised to explain the
of reticular formation hypofrontality theory. effects of arousal and/or stress on performance in
Adam, Teeken, Ypelaar, Verstappen, and Paas general, including cognition. No theory is based
(1997) also moved away from the inverted-U on exercise alone. Authors using these theories
theories, choosing Humphreys and Revelle’s to underpin their hypotheses in acute exercise–
(1984) theory as the underpinning for their cognition interaction studies assumed that exer-
study. Humphreys and Revelle saw arousal as cise is a stressor and will affect cognition in the
being a state of “alertness, vigor, peppiness, and same way as other stressors. Most are inverted-
activation” (p. 157) and effort as being a “moti- U theories but demonstrate some differences to
vational state commonly understood to mean one another. Kahneman (1973) saw arousal as
trying hard or being involved in a task” (p. 158). being unidimensional; however, Sanders (1983)
They described allocation of resources to a task divided it into arousal and activation. Both,
as “on-task effort” (p. 158). Humphreys and however, believed that effort is the key in allo-
Revelle did not believe in the pure inverted-U cating resources to the task. Kahneman (1973),
relationship between arousal and performance. Sanders (1983), and Hockey (1997) claimed that
They saw increases in arousal as being benefi- there are evaluation processes that provide effort
cial to what they termed “sustained informa- (the supervisory controller in Hockey’s model)
tion transfer tasks” (p. 154), but detrimental to with the necessary information to aid allocation
short-term memory tasks. By sustained infor- policy. Thus, we can say that these theories have
mation transfer tasks, they meant tasks that many similarities. Although drive theory dif-
primarily require attention and alertness. They fers in many areas, it too involves an evaluation
believed that both increases in arousal and on- process of sorts, with its determination of the
task effort would facilitate performance. Hence, incentive value.
6
1. A COGNITIVE PSYCHOLOGY APPROACH
EMPIRICAL RESEARCH Harvard Step Test protocol. Meyers et al. (1969)
used a similar step-up protocol but had subjects
A literature search using the computer data- work for 5 min. McAdam and Wang’s (1967)
bases PsycARTICLES, PsycINFO, PubMed, subjects carried out a run–jog–walk protocol
SPORTDiscus, and Web of Knowledge was for 10 min. According to the authors, this was
undertaken. Key words used in the searches “designed to work up a mild sweat, but not to
were combinations of “acute,” “exercise,” fatigue” (p. 209). It is easy to criticize such pro-
“cognition,” “cognitive function,” “cogni- tocols but we should remember that exercise
tive performance,” “reaction time,” “response physiology, as we know it today, was only in its
time,” “accuracy,” “error,” “working memory,” infancy. In fact, in most countries it was nonex-
“short-term memory,” “long-term memory,” istent. The situation was to change for the better
“memory,” “recall,” “executive function,” “cen- following Tomporowski and Ellis’ (1986) semi-
tral executive,” “oddball,” “visual search,” nal review. Tomporowski and Ellis criticized
“attention,” “anticipation,” “coincidence antici- unscientific protocols and the lack of a theoreti-
pation,” “decision making,” “flanker task,” cal framework behind most studies. While we
“Simon task,” “Sternberg test,” “Wisconsin card have looked at developments in the latter in the
sorting task,” “Tower of London,” and “Tower previous section, here we will examine changes
of Hanoi.” In addition, reference lists from in research designs that have occurred since
empirical reports and reviews were examined. Tomporowski and Ellis’ review.
Studies were included if they were performed Some research following Tomporowski and
on healthy individuals; the exercise intervention Ellis’ (1986) paper displayed the same exercise
required the activation of large muscle groups; protocol weakness as the early research, e.g.,
repeated measures, within-subject design, were Lawless (1988) had participants run on the spot
used; data were provided showing the intensity for 120 s prior to cognitive testing, while Beh
of the exercise with reference to a maximum or (1989) had her participants do 60 s of step-ups
threshold; exercise intensity was based on objec- before testing. These designs are obviously lack-
tive measures; the range of measures for a spe- ing in control, we simply have no idea about the
cific intensity was not >10% maximum volume intensity of exercise. However, Tomporowski
of oxygen uptake (V˙ O ) or equivalent; and and Ellis’ main criticism was concerned with
2MAX
the dependent variables were objective. Studies a failure to take account of individual differ-
including pharmacological treatments were not ences in capacity. For example, Davey (1973)
included. had all participants work at 420 kg/m over
Before examining the findings of these stud- 15 s; 840 kg/m over 30 s; 2800 kg/m over 2 min;
ies it is important to look at two issues with the 4200 kg/m over 5 min; and 7000 kg/m over
design of the research, which will aid our under- 10 min, regardless of their own level of fitness.
standing of the results, namely the exercise pro- He failed to take into account the fact that indi-
tocols used, especially the exercise intensities, viduals’ maximum workloads differ, therefore
and the types of task used. although these absolute workloads are identical,
they are at different percentages of each individ-
ual’s maximum. Hence, the relative intensities
Exercise Protocols
are not identical.
Early research was not only atheoretical but Some studies prior to Tomporowski and Ellis’
the nature of the exercise protocols left much to (1986) review had probably inadvertently taken
be desired. Gutin and Di Gennaro (1968a) had into consideration individual differences with
subjects undertake 1 min of step-ups, using the regard to fatigue. The authors of these studies