Authors: Marcus Yung and Richard Wells
How do we measure neuromuscular fatigue at the workplace? The Toronto CRE-MSD workshop (PDF)
Fatigue can be defined in multiple ways, but it is a phenomenon that is generally associated with terms such as weariness, exhaustion, tiredness, sleepiness, and weakness. In occupation settings, fatigue has been used to describe both work and the human body, where energy was seen as the limiting factor in production1. As new forms of work emerged, so has increased levels of physical and mental fatigue2,3.
In the short term, fatigue is linked to increased risk of accidents, which might result in fatal and non-fatal injury. In the longer-term, fatigue may be a precursor to the development of work-related musculoskeletal disorders5, and may lead to compromised immune function and other adverse health outcomes, including myalgia, chronic fatigue syndrome, and burnout2. Fatigue has also been cited as an important intermediary in the relationship between ergonomic risk factor and work performance deficits, i.e., quality and productivity4. In Canada, abnormal levels of self-perceived fatigue is found in up to 20% of the working population5.
Fatigue manifests itself in various forms, so a single test to measure fatigue is not reasonable. Because different measures provide information on different fatigue processes, fatigue should be evaluated by a multidisciplinary approach3 with a complementary set of measures6. However, given the large number of measures and detection methods, this begs the question, which measures are most efficacious to detect fatigue in the workplace?
A
workshop,
consisting
of
14
researchers,
was
convened
to
critically
evaluate
fatigue
measures
from
different
research
disciplines
and
perspectives.
At
the
beginning
of
the
workshop
the
group
operationally
defined
fatigue.
The
definition
considered
potential
effects
of
fatigue
in
occupational
tasks,
its
potential
impact
on
the
health
and
wellbeing
of
the
individual,
but
did
not
confine
fatigue
to
a
single
mechanism
or
impairment
of
a
specific
system.
Fatigue
is
a
process
that
results
in
the
impairment
of
wellbeing,
capacity,
and/or
performance
as
a
result
of
[work]
activity.
The
workshop
was
then
segmented
based
on
four
areas
of
discussion.
First,
researchers
were
asked
to
identify
general
outcome
domains
potentially
affected
by
fatigue.
Second,
discussion
centered
on
potential
sub-outcomes
and
effects
within
each
outcome
domain.
Third,
potential
causes
and
physiological
mechanisms
for
these
sub-outcomes
and/or
effects
were
identified.
And
lastly,
fatigue
measurement
and
detection
methods
were
reviewed
to
best
address
the
quantification
of
the
proposed
causes
and
mechanisms.
This
workshop
structure
shifted
the
focus
onto
the
outcomes
and/or
effects
of
fatigue
to
help
identify
measures
that
could
be
meaningful
for
workplace
evaluation.
Participants
identified
57
unique
measures
based
on
4
outcome
domains:
work
performance
and
quality,
injury
and
disorders,
illnesses,
and
discomfort.
Common
measures
were
grouped
together
and
directly
linked
to
outcome
domains.
By
doing
so,
measures
that
would
be
useful
as
indices
for
multiple
workplace
fatigue
outcomes
were
documented.
Three
measures
were
linked
to
all
four
main
outcome
domains:
questionnaires
and
fatigue
scales;
Borg’s
rating
of
perceived
exertion/discomfort
scales,
and
visual
analog
scales.
Conclusion
By assembling expert opinion from multiple research perspectives and disciplines, fatigue measures and detection methods were identified for workplace investigations. Fatigue researchers arrived to 57 unique measures, three were linked to all four outcome domains (work performance & quality, injury & disorders, illness & wellness, and discomfort). These measures should be considered for inclusion into a larger test battery of fatigue measures. However, the results of this workshop serve as a guide and it is the researcher or practitioner’s discretion to select appropriate detection methods.
Key messages
- Fatigue is linked to both short and longer-term health outcomes.
- A workshop was convened to identify fatigue measures which are feasible for workplace use.
- Fatigue was defined as: a process that results in the impairment of wellbeing, capacity, and/or performance as a result of [work] activity.
- Fifty-seven unique measures were identified from four fatigue outcome domains: work performance and quality; injury and disorders; illnesses and discomfort.
- Measures linked to all four domains were questionnaires & fatigue scales, Borg’s RPE/RPD scales, visual analog scales.
Implications for the prevention of MSD
Fatigue may be a precursor or potential biomarker for long-term outcomes, including MSD. Therefore, fatigue may be a useful risk indicator and a design and evaluation tool.
However, a single test to measure a single function is not reasonable. We confirm that fatigue is complex, involving multiple mechanisms, and can be measured by multiple measurements and detection methods.
Three measures were linked to multiple fatigue outcomes and should be considered for inclusion, as part of a larger test battery of fatigue measures, to detect fatigue at the workplace.
References
- Hockey, R. (2013). The psychology of fatigue: Work, effort and control. Cambridge University Press: Cambridge, UK.
- Kajimoto, O. (2007). “Development of a Method of Evaluation of Fatigue and its Economic Impacts.” In Fatigue Science for Human Health, edited by Y. Watanabe, B. Evengård, B. H. Natelson, L. A. Jason, and H. Kuratsune, 33-46. Toyko, Japan: Springer.
- Saito, K. (1999). Measurement of fatigue in industries. Ind. Health, 37, 134-142.
- Kolus, A., Yung, M., Neumann, W.P., Wells, R.P. (2014). Neuromuscular fatigue as an intermediary in production errors. Presented at Industrial & Systems Engineering Research Conference (ISERC). Montréal, Québec.
- Iridiastadi, H., & Nussbaum, M. A. (2006). Muscle fatigue and endurance during repetitive intermittent static efforts: development of prediction models. Ergonomics, 49, 344-360.
- Yung, M., Bigelow, P. L., Hastings, D. M., & Wells, R. P. (2014). Detecting within- and between- day manifestations of neuromuscular fatigue at work: An exploratory study. Ergonomics,57,1562-1573.DOI: 10.1080/00140139.2014.934299.
Last updated: 2016
Disclaimer: Position papers are funded by the Centre of Research Expertise for the Prevention of Musculoskeletal Disorders, which receives funding through a grant provided by the Ontario Ministry of Labour. The views expressed are those of the authors and do not necessarily reflect those of the Centre nor of the Province.