Integrating Theoretical Approaches to Promote Physical Activity Leonard H. Epstein
Research on the promotion of physical activity has been based on a variety of conceptualmodels. These models generally target one level of analysis, such as the individual,community, or the environment, and differ in their relative contact with basic or appliedscience. There have been limited attempts to develop approaches that target multiple levelsof analysis and can stimulate basic and applied research.
Theoretical integration in a multidiscliplinary field such as promotion of physical activityshould take into account that social, behavioral, and biomedical colleagues may usedifferent explanatory models, and use different approaches to the development ofscientific knowledge. This essay argues for the development of integration of theory acrossmultiple domains that can incorporate methods and findings of basic and appliedscientists, and that uses language and methods common to social, behavioral, andbiomedical scientists.
Behavioral choice theory is presented as an example of one theoretical approach thatbridges different approaches to physical activity intervention, and that can stimulate bothbasic and applied research on physical activity. Behavioral research on choice was discussedin relationship to basic research, human laboratory research, and community and clinicalresearch.
Implications of behavioral choice theory for community and environmental change wasdiscussed. The essay ends with ideas for future directions in integration of theory forphysical activity research. Medical Subject Headings (MeSH): physical fitness; health promotion; leisure activities (recreation); models, theoretical; behavior (Am J Prev Med 1998;15(4):257–265) 1998 American Journal of Preventive Medicine
mental laws that influence behavior, while applied
research uses knowledge gained in basic work. Anotherdistinction among scientific approaches is the concep-
Withinactivityasamajorpublichealthprob- tualization of methods of inquiry as “bottom up” or
“top down.” Bottom up approaches attempt to under-
suggested to modify physical activity. The
stand a phenomenon by examining the building blocks
Surgeon General’s report on physical activity provides
of the phenomenon. Basic scientists are often inter-
an excellent overview of a variety of conceptual ap-
ested in understanding how the component parts work,
proaches to increasing physical activity.1 This report
and then attempting to relate the component to the
presents eight different models of behavior change that
integrated organism. The top down approach argues
are focused at three levels of analysis: individual, inter-
that you have to study the integrated organism in the
context in which the organism normally behaves. Pro-
There are distinctions other than level of analysis
ponents of the top down approach believe that studying
that can be drawn between approaches to research on
the component parts separately will not inform you
the promotion of physical activity. One distinction is
how they work together in the complex organism.
the extent to which research is basic or applied. Basic
Differentiation of theoretical approaches to a prob-
research is designed to develop knowledge on funda-
lem broadens the scope of intellectual inquiry byincluding a variety of assumptions, investigative para-
From the Department of Psychology, University at Buffalo, Buffalo,
digms, and methods of inquiry. It takes time and a body
of research to understand the strengths and limitations
Address Correspondence to: Dr. L.H. Epstein, Department of
of different theoretical perspectives. As a field matures,
Psychology, University at Buffalo, Park Hall, Box 604110, Buffalo,New York 14260-4110.
a more parsimonious theory or conceptual approach is
1998 American Journal of Preventive Medicine
needed that can address issues across levels of analysis,
level of analysis, and conceptualize problems using
providing a common language and set of concepts that
tools of basic and applied sciences.
are relevant to the field. The research questions thatare asked become refined, and answers often shift from
Behavioral Economics or Behavioral Choice Theory
complex interactions in multivariate models to morebasic mechanisms that operate for selected groups of
Behavioral economics, or behavioral choice theory,5,6 is
a theoretical approach that attempts to understand
There is another challenge for researchers interested
decision making and how time and responses are
in the promotion of physical activity. This area of
allocated given the options available. The theory is
research usually involves multidisciplinary collabora-
based in part on basic research on learning,7 cognitive
tions. For example, a team might include specialists in
psychology and decision making,8,9 and economics.10
behavior change, health care, and exercise physiology,
As will be illustrated in the next section, this theoretical
interested in increasing activity, the effect of exercise
approach has been used to guide basic and applied
on a disease process, and quantification of the changes
research across individual, community, and environ-
in fitness that mediate the changes in health outcome,
mental levels of analysis. Behavioral choice theory may
respectively. These investigators address different as-
also be useful in bridging the gap between social and
pects of the problem using theories and methods
behavioral science and biomedical researchers. New
comprehensive theories have combined biological con-
Members of a multidisciplinary team can benefit
trol theory2 and learning theory4 with many common
from theoretical approaches that are relevant to bio-
constructs in behavioral choice theory and biological
medical as well as social and behavioral scientists.
control theory. In addition, behavioral choice theory
However, there are several factors that may impede a
includes a strong tradition of theory building anddeductive research, as well an equally strong tradition
common theoretical approach in multidisciplinary re-
of inductive, or empirical, approaches to knowledge
search. First, the working models and approaches to
acquisition.5 A similarity in approaches to knowledge
theory that biomedical researchers often use are very
acquisition in the social and behavioral and biomedical
different from those used by social and behavioral
sciences may make it easier to develop integrated
science researchers. Biomedical researchers often use a
model of physiological regulation based on homoeo-static control and positive and negative feedback.2 Thismodel is generally not used in most social and behav-
ioral science theories, with exceptions.3,4 Second, most
There are several general principles that can be derived
biomedical researchers use a combination of empiri-
from research on basic behavioral choice theory. These
cally derived (inductive) and deductive theoretical
principles can be applied to sedentary individuals, who,
models to approach a problem. Many social science
given the opportunity between sedentary and physically
approaches are strongly tied to deductive models of
active alternatives, will reliably choose the sedentary
inquiry, and research that is not theory-based, or does
alternative. First, choice of an alternative depends on
not conform to the use of deductive models, is consid-
the behavioral cost.11 Thus, even very powerful phar-
ered inferior and less likely to yield new scientific
macological reinforcers, such as addictive drugs, are
knowledge. This bias disregards the fact that theory
subject to the demands of cost. This general principle
building can include both inductive (empirical) and
provides an empirical basis for policy decisions that
deductive (model testing) approaches. Both ap-
attempt to reduce demand by increasing the cost of a
proaches contribute to knowledge, and major advances
substance.12,13 The choice of being sedentary is very
in a field are often based on new approaches and a
responsive to cost,14–16 and reducing the accessibility of
paradigm shift, rather than knowledge derived from
sedentary behaviors or increasing the cost of being
deductive theory testing. It is likely that a combination
sedentary are both methods for reducing sedentary
of inductive and deductive approaches is best.
The goal of this essay is to present a brief overview of
A second general principle is that the choice and
behavioral choice theory, and show how this theory can
reinforcing value of a commodity depends in part on
incorporate methods and findings relevant to basic and
the available alternatives. Providing a reinforcing alter-
applied investigators, using bottom up and top down
native can shift choice, without changing cost or avail-
approaches, across multiple levels of analysis. The goal
ability of the usual choice. For example, Higgins and
is not to present this as the best approach to research
colleagues17 have demonstrated that cocaine self-ad-
on promoting physical activity, but rather to illustrate
ministration (10 mg unit dose) in cocaine users can be
how investigators interested in modifying physical ac-
reduced by providing alternative monetary reinforcers
tivity can utilize theories that address more than one
(up to $20.00). While subjects may generally choose to
American Journal of Preventive Medicine, Volume 15, Number 4
be sedentary, choice may shift if the sedentary behavior
immediately available. This phenomenon has been
is not valued as highly as the active alternative.
labeled impulsive behavior, and individual differences
The reinforcing value of the alternative is not static,
in the shift from more valuable to less valuable alterna-
but may change over time or be modified by other
tive is an index of impulsivity. Subjects who switch
behaviors. Experience with the alternative can influ-
quickly as the more valuable reinforcer is delayed are
ence the extent to which an alternative can substitute
more impulsive. This is very relevant to physical activity
for the usual choice. For example, Carrol and col-
since some of the benefits of being active are delayed,
leagues studied the relative reinforcing value of cocaine
while benefits of sedentary alternatives may be imme-
versus water sweetened with glucose and saccharin.18
diately experienced. This self-control paradigm is cen-
For animals who were dependent on cocaine, animals
tral to understanding choice and decision making21
chose cocaine almost exclusively. However, for animals
and has provided interesting individual differences in
who first had experience with sweetened water, they
the reinforcing value of food in humans.22
were less likely to become dependent on cocaine,
Behavioral choice theory is based in part on under-
suggesting that access to an alternative reinforcer re-
standing factors that influence the reinforcing value of
duced the development of drug dependence. A similar
an alternative, and thus behavioral choice theory makes
effect of experience with the nondrug reinforcer has
contact with biological mechanisms involved in rein-
been observed on the development of cocaine self-
forcement. There is considerable interest in neuro-
administration in primates.19 The observation that ex-
sciences in identifying the biological mechanisms of
perience with an alternative nondrug reinforcer can
reinforcement, and progress has been made in identi-
influence the development of dependence is important
fying the biological basis of psychostimulant drugs and
as we consider how to increase activity. Early exposure
food.23,24 One of the major new theories on psychobi-
to an active lifestyle may protect some from the rein-
ological mechanisms for drug reinforcement include
both the dopaminergic and opioid systems. Robinson
A third general principle is that choice is important
and Berridge23 argue that the opioid system is involved
to motivate people to obtain a reinforcer. For example,
in liking, or the affective quality of a stimulus, and the
Wolffgramm20 and colleagues compared rats provided
opioid system contributes to the motivational drive to
access to a choice of alcohol or water, to rats forced to
obtain the stimulus, which is regulated primarily by the
consume alcohol by providing that as the only fluid
dopaminergic system. These two systems can be acti-
option, versus a control group that had access only to
vated independently. Long-term drug reinforcement,
water. After eight months of access to alcohol, the rats
and perhaps mechanisms for many nonpharmacologi-
were tested for dependence, and then abstained from
cal reinforcers, depend on activation of the dopaminer-
alcohol for three months. Rats were then reintroduced
gic system, and people may be motivated to use drugs
to alcohol to test the extent to which alcohol became a
even in situations where they report not liking the drug.
reinforcer. Only rats who were given the choice to
Behaviors such as physical activity may not be moti-
consume alcohol during development of dependence
vated exclusively by positive reinforcement. Many stud-
chose to drink it. Being forced to consume alcohol did
ies have used a negative reinforcement model for
not establish alcohol as a reinforcer. Similarly, rats had
exercise, focusing on stress reduction and negative
choice or forced access to opiates for 30 weeks, were
affect reduction as motivations to be physically active.25
tested for dependence, and then were abstinent for 19
Robinson and Berridge23 acknowledge that negative
weeks. Only animals that initially chose the opiate
reinforcement can make a contribution to motivated
self-administered it later. Thus, in order for these
behaviors such as drug use, but they argue that in many
powerful drugs to become reinforcers, consumption
situations, and for many people, the positively reinforc-
had to be voluntary, rather than forced. If people
ing effects of the drug predominate. This may be a
perceive that they are forced to initiate activity pro-
relevant distinction for physical activity, since the posi-
grams as part of treatment, but do not perceive that
tively reinforcing effects of activity have not received as
they chose to be active, they may not be motivated to
much attention as the stress-reducing effects of physical
make being physically active part of their lifestyle.
A fourth general principle is that choice depends in
Behavioral genetics may yield important insights into
part on the delay between choosing and receiving the
factors that influence physical activity as a reinforcer.
alternatives. In many choice situations, the outcomes
Significant progress has been made in the genetics of
are delayed from the responses. When human subjects
the dopaminergic system for drug susceptibility and
are provided a choice of two reinforcers immediately
food.26 There has been considerable interest in the
available, subjects reliably choose the more valuable
genetics of fitness, and genetic responses to training,27
reinforcer. But as the more valuable reinforcer is
but to my knowledge there are no data that would link
delayed, subjects may switch from the more valuable
genetics to individual differences in reinforcing or
delayed reinforcer to the less valuable reinforcer that is
physical activity more then lower valued sedentary
The observation that children are more physically
Although physical activity is part of a healthy lifestyle,
active when the alternative is a lower preference seden-
approximately 40% of the population remains com-
tary behavior suggests that reducing access to high-
pletely sedentary and the majority of the United States
preference sedentary behaviors may increase activity.
population is not active enough to derive health bene-
We found in a series of laboratory studies that reinforc-
fits from their physical activity.1,28 The majority of
ing obese children for decreasing high-preference sed-
leisure time, and increasingly more work time, is spent
entary activities such as television watching and video
being sedentary. Inactivity is a significant public health
game playing was associated with increases in physical
activity that are similar to the changes that occur when
Some people find exercise to be very reinforcing,
physical activity is reinforced.15,16 These studies also
and engage in physical activity on nearly a daily basis.
suggest that sedentary activities do not readily substi-
Others find sedentary activities more reinforcing. One
tute for each other. If sedentary activities were com-
important variable that may influence physical activity
pletely substitutable, children would replace all prior
is obesity. Epstein et al.14 found that when obese and
time spent in high-preference sedentary activities with
nonobese children were given the choice between
time engaged in low-preference sedentary activities.
sedentary and active alternatives, they chose to spend
Liking of activity is often considered to be an impor-
the majority of their time being sedentary. However,
tant influence on activity, but liking represents a differ-
when the cost of being sedentary was increased, a direct
ent construct than reinforcing value, with a different
relationship was observed between the degree of obe-
psychobiological basis.23 To test the influence of liking
sity and substitutability of physically active for sedentary
of different physical activities on choice, Epstein et al.14
behaviors. Very obese children did not switch to phys-
gave children the choice of a highly liked sedentary
ical activities despite large disparities in the work re-
activity and either a highly liked physical activity or a
quired to obtain access to sedentary versus physical
least liked physical activity. When the sedentary and
physical activity options were equally available in both
The cost of being physically active is related to the
tasks, children chose to be sedentary. Children de-
accessibility of physical activity, and it is not surprising
creased their choice of being sedentary with increasing
that accessibility is correlated with activity levels.29 In a
cost for sedentary activity, but the point of switching to
laboratory test of the influence of accessibility on
physical activity was the same regardless of whether the
choice of sedentary and physically active alternatives,30
physical activity option was highly liked or least liked.
we randomized sedentary male college students to
If sedentary behaviors are more reinforcing for some
groups that varied the proximity of sedentary and
people than being active, perhaps sedentary behaviors
physical activities, with near defined as immediately
can be used to reinforce these people for being more
accessible in the same room and far as a 5-minute walk.
active. Saelens and Epstein32 studied whether making
When sedentary alternatives were near, subjects chose
sedentary activities such as video game playing and
to be sedentary, but when sedentary activities were far
watching movies on a videocassette recorder contin-
and physical activities were near, subjects spent the
gent on riding the cycle ergometer would increase
entire session being physically active. The requirement
physical activity. In a control group, being active or
of making people walk for 5 minutes to get access to
sedentary was freely available. Children in the contin-
sedentary activities was enough to shift their choice to
gent group dramatically increased their physical activity
physical activity. This makes a strong case for reducing
to get access to television activities even though other
proximity to sedentary behaviors to prompt the choice
sedentary activities were freely available, whereas those
in the control group remained sedentary. There may be
How powerful are different sedentary behaviors in
considerable potential for motivating activity by arrang-ing access to sedentary activities that are normally freely
competing with being active? Saelens and Epstein31
provided children the choice between physical activityand high- or low-preference sedentary activities, withpreference defined by the amount of time the child
spent in that activity during a baseline session. Children
choose to be more physically active when given thechoice between low-preference sedentary activity and
One of the first studies to highlight the choice among
physical activity than when the choice was between
active alternatives was by Brownell and colleagues33
high-preference sedentary activity and physical activity.
who observed over 45,000 choices of people taking the
Highly valued sedentary activities may compete with
stairs or an escalator in a shopping mall, train station,
American Journal of Preventive Medicine, Volume 15, Number 4
and bus terminal. After collecting baseline data, a
tions that involve decision making as intervening vari-
colorful sign depicting a heart using the stairs was
ables in activity level. For example, the stages-of-change
placed at the choice point between the escalator and
model uses the construct of decisional balance theory
stairs. The use of the stairs doubled, and remained
to understand why people choose to be active or not.41
doubled over 15 days. The use of stairs decreased when
This approach is based on rational choice theory, in
the sign was removed. These results show that small
which people weigh the pluses and minuses of their
prompts to be active may alter choice of physical
decisions, and respond on the basis of a hypothetical
activity. The influence of a sign to modify stair versus
balance sheet. Contemporary decision and choice the-
ories have recognized limitations of rational choice
Wolffgramm and Heyne20 found that in basic animal
theories, and have attempted to include additional
research, choice of a behavior is important for motiva-
variables in the decision-making process.6,42,43 Behav-
tion to repeat that behavior. In naturalistic settings,
ioral choice theory may represent an approach that
perception of choice may be as important as actual
extends beyond rational choice theory to improve the
control of choice. Thompson and Wankel35 studied
prediction of choice. An example of the influence of
females who had enrolled at a health club and were
psychological variables on choice is research on impul-
randomized to one of two groups. Subjects were asked
sive behavior and self-control that provides subjects
their activity preferences, and then randomized to
with a choice between alternatives that are provided at
groups who were provided a standardized exercise
different points after the choice, such as a pencil now,
program set up by the staff, or subjects were told their
or five dollars in two weeks. This choice depends not
program was based on individual preferences. At the
only on the rational choice of which is more valuable,
end of the six weeks, adherence was significantly
but also individual differences in waiting for the larger,
greater for subjects who perceived that they had choice
over their exercise program, versus those who did nothave choice.
The generalizability of laboratory studies that reduce
access to sedentary behaviors14 was tested for obese
children participating in family-based weight controlprograms. Children and their families were random-
Behavioral choice theory has been extended to com-
ized to groups in which they were reinforced for being
munity interventions and used to influence policy
more active, reinforced for being less sedentary, or
decisions for important community problems such as
reinforced for the combination of the two.36 All chil-
drug use,12,13 energy conservation,44 and obesity.45 One
dren were provided the same dietary changes. At one
extension of behavioral choice theory is to increase the
year, the best changes in obesity were seen for children
cost of drugs, thereby reducing their use. Increasing
reinforced for reducing sedentary behaviors. Each
the tax on drugs can reduce demand, but the influence
group showed similar changes in fitness. The improve-
will be greater in situations in which the reinforcing
ment in weight control was probably due in part to shift
value is less, as in new users, or situations in which there
in allocation of time from sedentary to physically active
are other powerful alternative reinforcers.12 Likewise,
alternatives, and to a decrease in eating opportunities
taxing can influence food consumption. Brownell has
as time in sedentary behaviors was decreased.
argued that the increase in obesity is due to a toxic
There are additional studies that suggest that in-
environment that fosters increased intake of food and
creased choice and control are related to better adher-
decreases activity. Taxing snack foods significantly re-
ence to activity programs. King and colleagues random-
duced snack food intake in California,46 which is easy to
ized sedentary elderly adults to structured aerobic
understand given the vast options available to consum-
exercise conditions at exercise sites versus home-based
ers of acceptable food alternatives. Obviously, increased
exercise where subjects had more flexibility regarding
cost of engaging in a behavior will be less effective if
when and where to exercise. Long-term results showed
better maintenance for the home-based, rather than
There are potential monetary incentives that could
site-based exercise programs.37 Perri and colleagues
be used to influence physical activity at the community
similarly showed that home-based exercise programs
level. Incentives could include reduced insurance pre-
were superior to site-based programs for the treatment
miums for regular exercisers, or tax rebates for busi-
of obesity.38 More flexible, lifestyle activity programs
nesses that arrange environments that promote activity,
are also associated with better weight loss up to two
or direct reinforcement for regular exercise, with the
years after initiation of treatment in obese children.39,40
amount of exercise related to the amount of rebate at a
Behavioral choice theory provides a rich theoretical
health club. It might be interesting to consider taxing
framework for understanding how people make
people for car use, with the money being used to
choices, and therefore may be able to improve predic-
increase access to active modes of transportation to
work. Pay-per-view television, more costly movies, and
people who lived within two miles of work, and had safe
increasing the cost of video games might influence the
level of sedentary behavior, though it is difficult to
Finally, as community, environmental, and policy
imagine the circumstances that would give rise to these
approaches to physical activity are considered, it is
important to keep in mind the importance of choice
It is not necessary to use monetary incentives to
and the perception of control in developing options for
promote physical activity. Behavioral choice theory
being active. There is a delicate balance between ag-
suggests that environmental changes that both increase
gressively promoting, encouraging, and reinforcing
the proximity and convenience of physical activity and
physical activity and the need to boost self-regulation
decrease access to sedentary activities can increase
and control. At a policy level, it is often assumed that
physical activity. Unfortunately, environments have be-
restriction of things that are bad for you is the best
come saturated with labor-saving and convenient sed-
approach, and the more restriction, the better the
entary activities that decrease the need to be physically
approach will work. However, restriction is a powerful
active. It is possible that such sedentary environments
method for increasing the reinforcing value of the
have increased the value of sedentary activities or
behavior that is being restricted. Reduction can also
decreased the value of physical activity, both of which
take place by reinforcing people for reducing their
would contribute to higher rates of sedentary activity.
behavior, rather than restricting access to the behavior.
Interventions that increase access to opportunities for
For example, we were able to increase activity and
being active, such as creating bicycle lanes, providing
decrease liking of being sedentary more by reinforcing
more opportunities for children to be active, and
sedentary children for being less sedentary than by
ensuring that indoor walking is available for inclement
removing the television, VCR, and computer games
weather, may have some impact on activity. Likewise,
reducing access to sedentary behaviors may have animpact on activity, as people have to make choices
about new ways to allocate time. It is logical thatinterventions that both increase access to active oppor-
The purpose of this paper was to encourage investiga-
tunities as well as decreasing access to sedentary behav-
tors to integrate theoretical perspectives that address
iors are most likely to have long-term success.
multiple levels of inquiry. This includes paradigms
There are many things that are possible in contem-
within the social and behavioral sciences that may
porary workplaces that could increase activity by mod-
target different levels of influence, as well as paradigms
ifying lifestyles. A great example of a choice situation in
that can bridge basic and applied interests, as well as
many workplaces is the choice to take the elevator or
top-down or bottom-up approaches to knowledge ac-
the stairs. This choice may be influenced not only by
the motivation to be more active, but by accessibility to
This paper dealt with one approach, behavioral
elevator or stairs. It is more common to have easy access
choice theory, that can serve as an example of a theory
to an elevator that is well lighted and freshly painted,
that can organize and stimulate research across multi-
while the stairs are hidden, locked, or dirty. It would be
ple levels. This discussion will focus on two issues,
interesting to assess stair use in situations in which the
future directions in theory integration for physical
stairs are easily accessible and brightly lit, with music
activity, and future directions for behavioral choice
activated by the footsteps, while the elevator is hard to
theory in physical activity research.
find and dimly lit. Choice of stair use over escalator orelevator is a good target for environmental studies, as
Future Directions in Theory Integration for
research has shown it may be relatively easy to
Physical Activity
The incorporation of increased activity into lifestyles
Physical activity research has benefitted from social and
is one of the most interesting new approaches to
behavioral science research, whereas physical activity
promoting physical activity. One very important com-
research in biomedicine has often contributed to fun-
ponent of lifestyle exercise is using transportation as a
damental new knowledge. Attempts to assess whether
form of exercise. Walking or bicycling to work would
social and behavioral science research in physical activ-
provide the opportunity for many people to get all the
ity can develop fundamental new knowledge or theory
exercise they needed in a day, without the need to find
additional time to be active. Businesses would need to
Theories can be developed in part from new princi-
provide opportunities for employees to have lockers
ples or advances in fields other than social and behav-
and a place to shower to take advantage of using
ioral science. There are numerous examples of this in
transportation as a form of physical activity. It would be
regard to basic theory construction. For example, be-
interesting to evaluate this by studying a sample of
havioral choice theory has borrowed considerably from
American Journal of Preventive Medicine, Volume 15, Number 4
economic theory,6 behavioral momentum theory has
haviors is needed. People may be inactive because they
borrowed from physics,47 and new approaches to nutri-
find sedentary behaviors reinforcing and/or because
tional assessment have borrowed from developments in
they do not like to be physically active. Individual
differences may assist investigators in matching inter-
The use and development of theoretical approaches
ventions with the characteristics of the sedentary sub-
that are accessible to both biomedical and social and
jects. If there are individual differences, are they influ-
behavioral scientists are needed. When possible, inte-
enced by genetic factors? Will developing a better
grative approaches that utilize common theoretical
understanding of genetics and reinforcement provide
constructs should be encouraged. An excellent exam-
clues to why people differ in their motivation to be
ple of this is the use of negative feedback theory in
active? Are these individual differences influenced by
learning? Can environments be arranged that maxi-
Differences in use of inductive and deductive theo-
mize the development of a motivation to be active?
rizing across social and behavioral sciences and bio-
Ideas about choice of being active, rather than forced
medical sciences should be better appreciated, and
activity; the use of activity as a reinforcer, rather than an
both approaches to knowledge acquisition integrated
instrumental response; pairing physical activity with
in future theoretical development for physical activity.
pleasant associations; and the arrangement of environ-
More rigorous evaluation of what constitutes theory
ments that foster physical activity and suppress being
and theoretical models is needed, rather than elevating
sedentary may provide theoretical constructs that can
ideas and conceptual approaches to physical activity as
theories. It should be possible to confirm, or discon-
Can deprivation of physical activity be used to make
firm, theories applied to physical activity research, such
activity more reinforcing? As deprivation increases the
that some theories are tested and discarded. It is
reinforcing value of food, can deprivation increase the
generally the case that lists grow, rather than shrink,
reinforcing value of being active? According to disequi-
with more research. No one wants to offend particular
librium theory of reinforcement,50 reducing physical
groups of investigators, and few theories are discon-
activity below baseline levels would result in an increase
in the reinforcing value of activity. It would be interest-
It is common in the social and behavioral sciences to
ing to determine if these brief shifts in reinforcing
make distinctions regarding controlling variables or
value could be used to produce more permanent shifts
mechanisms in terms of opposing classes of indepen-
in the level, and reinforcing value of activity.
dent variables, such as mind versus body, psychological
Behavioral economic analyses of physical activity
versus physiological, or environmental versus genetic,
bring into focus the significant impact that environ-
when the distinction is more an issue of level of analysis
ments have on our choices. More research is needed
than difference. A better appreciation of the integra-
that focuses on the influence of environmental context
tion of these positions in physical activity research is
to increase access to activity, increase the reinforcing or
punishing influence of the environment on physicalactivity, and establish the influence of the environmenton reducing access to sedentary activities. Future Directions for Behavioral Choice Theory
Is the low level of physical activity in part due to
Considerable progress has been made in understand-
environmental constraints on activity, or prompts to be
ing the substitutability of sedentary and active behav-
inactive, and might more progress be obtained by
iors, as well as substitutability within classes of sedentary
focusing on environmental and policy issues than on
behaviors. People will shift from being sedentary to
being active if the cost of being sedentary increases,14
Research is needed on behaviors that compete with
and people will not choose sedentary behaviors if access
being active. How reinforcing is it for some people to
to them is reduced.30 The types or variety14,49 of
be sedentary, and can we develop physically active
physical activities used as alternatives to being sedentary
substitutes to being sedentary? If this is not possible for
have not influenced physical activity when the alterna-
some people, how much constraint is required on the
tive is highly liked and preferred sedentary behaviors.
sedentary alternatives to shift choice from being seden-
However, the types of sedentary behaviors provided as
alternatives to the physical activities may be very rele-
Research on the reinforcing value of physical activity
vant. Reducing access to highly preferred sedentary
is needed that focuses on distinctions among physical
behaviors shifts activity, while reducing access to less
activities made by exercise physiologists that influence
preferred sedentary behaviors has little effect on
fitness. For example, is exercise intensity related to the
motivation to be physically active? Are there important
Additional research on individual differences in the
motivational differences among types of activities, such
reinforcing value of physical activity or sedentary be-
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Comentarios a la última Declaración de Helsinki, emitida en octubre de 2013 Pau Ferrer Salvans Institut Borja de Bioètica Secretario del CEIC del Hospital de San Juan de Dios de Barcelona Como es sabido la Declaración de Helsinki (DH) (1) es un documento de referencia, que desde el año 1964, en que fue publicada por primera vez, sirve de guía ética a los médicos que quieren
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