activity as any bodily movement that is produced by the skeletal muscles and which
results in the expenditure of energy. Of course, for any significant health benefits to be
derived from such energy expenditure, the activity would have to be well above resting
levels. Thus physical activity may be divided informally into such categories as
“moderate” (e.g., walking briskly) and “vigorous” (e.g., jogging, running). Another
popular distinction within this construct is that between “leisure time” physical activity
(where people choose to expend energy in the service of some hobby or interest) and
“occupational” physical activity (which is undertaken in the context of one’s job or
domestic setting). “Exercise” is usually regarded as being a sub-category of physical
activity. In other words, it is understood as a leisure-time physical activity that people
engage in for the purpose of developing physical fitness (which can be defined broadly as
“the ability to perform work satisfactorily”; Gauvin and Spence, 1995, p. 435). More
precisely, exercise is the “planned, structured, repetitive bodily movements that someone
engages in for the purpose of improving or maintaining” (Buckworth and Dishman, 2002,
p. 28) physical fitness or health. Of course, there is considerable overlap between the
terms “physical activity” and “exercise”. So, in keeping with the recommendation of
Biddle and Mutrie (2001), this chapter will use the term “exercise” to designate such
structured, leisure-time types of physical activity as walking, running, “keep fit” activities
and participation in recreational sports. By the way, psychologists distinguish between
two types of exercise behaviour: “acute” and “chronic” activity. Whereas acute exercise
refers to a single, relatively short bout of exercise, the criterion for chronic exercise is
that it is conducted several times a week for relatively long periods of time. They also
distinguish between the intensity with which the exercise is conducted. Interestingly,
recent research by Westerterp (2001) suggests that short bursts of high-intensity exercise
(e.g., “working out” in the gym) may not be as beneficial to health as is engaging in low-
intensity physical activities such as walking. Apparently, strenuous exercisers tend to
compensate for bouts of energy expenditure by doing less activity for the remainder of
the day!
In general, psychology researchers regard exercise as a multifaceted construct. For
example, it can include various types of physical behaviour which people perform alone
(e.g., a set of fitness exercises that one engages in before going to work) or in groups
(e.g., dance classes). It also includes activities that are categorised as being either
competitive (e.g., sport) or non-competitive (e.g., leisure pursuits) and “aerobic” (e.g.,
vigorous actions such as jogging which stimulate pulmonary and cardiovascular systems)
or “anaerobic” (e.g., less intense activities such as golf). In summary, despite its wide
variety of referents, the term “exercise” always involves the idea of exertion. This
exertion can be undertaken either as a means to an end (e.g., when climbing the stairs to
one’s office because the elevator is broken) or as an end in itself (e.g., going for a long
walk for the intrinsic pleasure of the activity itself; see also Chapter 2). Interestingly, we
shall see later in the chapter that the question of whether or not exercise has a purpose
and context has important implications for people’s willingness to adhere to it. Thus
Morgan (2001) argued that “Factor P”—a sense of purpose—is missing from many
exercise regimes that people adopt at present. In particular, he criticised much of the
exercise behaviour that people undertake in gymnasia as being “non-purposeful” because
it involves a great deal of “walking or running on a treadmill to nowhere, climbing stairs
to nowhere, cycling and rowing... to nowhere” (p. 372). It is not surprising, he suggested,
Sport and exercise psychology: A critical introduction 216