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EDITORIAL
‘‘Workload’’ – time to abandon?
As sport and exercise scientists, we are interested in
the scientific study of factors that influence the ability
to perform exercise. This study could be from the
standpoint of individual disciplines such as biome-
chanics, nutrition, physiology or psychology, but
increasingly approaches tend to be inter- or multi-
disciplinary. Irrespective of the approach, we are
bound by the principles of science and in particular
the Syste`me International d’Unite´s, or SI as it is
more commonly known to native speakers of
English. This system is characterized by universally
agreed terms and their associated quantities, units,
and symbols. Indeed, this is the name given to the
Royal Society’s 54-page handbook that was pub-
lished in 1975 by the Society’s Symbols Committee.
An important part of our work involves assess-
ments of individuals’ abilities to perform exercise,
which in turn requires the design and completion of
exercise challenges. These challenges can then
quantify the severity with which someone was
exercising or the ‘‘amount’’ of exercise that they
could perform to explore how they respond and
adapt to such exercise.
In spite of its shortcomings highlighted by
Knuttgen (1978) nearly 30 years ago, the term
‘‘workload’’ is still frequently though erroneously
used to indicate severity. Let us consider the term
carefully. The first part – ‘‘work’’ – implies that
mechanical work was done. That is, when:
A force moves its point of application such that
some resolved part of the displacement lies along
the line of action of that force.
(Hopper, 1973, p. 121)
In essence, it is calculated as the product of the
force in newtons (N) multiplied by the distance (m)
through which the force was applied and the units are
joules (J). In ‘‘workload’’, the implication is that
‘‘load’’ is the resistance experienced during the
performance of the work, and hence should be
referred to in newtons. For isometric activity, there is
no external mechanical work done, so ‘‘workload’’ is
simply inapplicable.
Moreover, it is not the mechanical work that is
necessarily important, it is the rate with which the
work is performed that is key. This is mechanical
power and the units are J s
71
, i.e. watts (W).
In the case of cycle ergometry, it is common to
read in a manuscript’s methods section, ‘‘The initial
workload was 100 W and this was increased by x W
per minute until the participant reached volitional
exhaustion’’. Similarly, in the context of running it is
not unusual to read something like, ‘‘Participants ran
at a workload of 10 km h
71
’’. These are units of
speed, not work or load. In both of these examples,
the use of the term ‘‘workload’’ is simply incorrect;
its use does not conform to the principles of the SI.
So, what is the alternative? Remember, we are
trying to describe the severity with which someone is
exercising. A suitable term is ‘‘intensity’’, a term that
was advocated by Knuttgen (1978). This term has
been adopted by some physiologists to describe
domains of exercise as moderate, heavy, very heavy,
and severe (Whipp, 1996). These domains are
categorized according to oxygen up take and con-
centrations of blood lactate and H
þ
. In fact, these are
not intens ities per se; they are physiological effects of
different intens ities.
The term ‘‘intensity’’ is universal and can be used
to describe all forms of exercise. It is only the units
that change according to the circumstances: new-
tons for isometric activity, watts for instance during
cycling, and metres per second (speed) for say
running and swimming. Moreover, the intensities
can be expressed as a percentage of maximal values
(i.e. maximal force, maximal power or maximal
speed). It is tempting to express physiological
responses such as heart rate and oxygen uptake as
proportions of their respective maxima. This might
be permissible for intensities performed at steady
state – that is, with little or no contribution from
anaerobic mechanisms – but when anaerobic meta-
bolism does contribute and the slow-component of
oxygen uptake occurs, permission has to be re-
scinded.
Ratings of perceived exertion can be used to gauge
an individual’s perceptions of severity to imposed
intensities (Borg, 1998).
The expression ‘‘intensity of exe rcise’’ should be
used to describe exercise challenges and the term
‘‘workload’’ should be banished from the lexicon of
exercise sciences. It is exceptionally rare – if it occurs
Journal of Sports Sciences, December 2006; 24(12): 1237 – 1238
ISSN 0264-0414 print/ISSN 1466-447X online Ó 2006 Taylor & Francis
DOI: 10.1080/02640410601072757
at all – for the use of the term fully to match the
principles and detail of the SI. ‘‘Intensity’’ can be
used universally – that is, irrespective of the form of
exercise. The adoption of the term means that
biomechanical, nutritional, physiological, and psy-
chological effects of exercise can be examined from a
firmer scientific base.
EDWARD WINTER
Sport Performance Section Editor
E-mail: e.m.winter@shu.ac.uk
References
Borg, G. (1998). Borg’s Perceived Exertion and Pain Scales.
Champaign, IL: Human Kinetics.
Hopper, B. J. (1973). The mechanics of human movement. London:
Crosby, Lockwood, Staples.
Knuttgen, H. G. (1978). Force, work, power and exercise.
Medicine and Science in Sports, 10, 227 – 228.
Whipp, B. J. (1996). Domains of aerobic function and their
limiting parameters. In J. M. Steinacker & S. A. Ward (Eds.),
The physiology and pathophysiology of exercise tolerance (pp. 83 –
89). New York: Plenum Press.
1238 Editorial
