Introduction
Bioelectric signals provide an extraordinary opportunity to discover and quantify
a wealth of phenomena associated with the organs that generate them. In addition,
they provide extensive potentially valuable information for medical doctors (MDs),
physiotherapists (PTs), occupational therapists (OTs), and movement scientists (MSs),
for functional diagnosis, patient path management, evaluation of patient recovery
and progress, and to document or quantify the effectiveness of treatments/trainings.
Clinical researchers and engineers have expected that such information would be highly
welcomed by clinicians because of the evidence that such information would add to
their rehabilitative activity. This has not been the case for surface EMG (sEMG),
a fact that motivated this Frontiers project, as well as the publication of a number
of tutorials and consensus papers (1–5), and some EU efforts since 1999 (6). A recent
Frontiers e-book illustrated sEMG scientific/technical innovations but did not address
the “barrier” problem (7).
This Frontiers Project presents 18 contributions from 7 countries and 80 authors (33
engineers, 16 MDs, 18 PTs and OTs, and 13 MSs) who are highly respected experts in
the many fields of sEMG. The general problem is addressed in Campanini, Disselhorst-Klug
et al., while results of interviews are presented in Manca et al., Feldner et al.,
and Cappellini et al. as well as the situation in specific countries (Manzur-Valdivia
and Joel Alvarez-Ruf; Portero et al.), and teaching/communication experiences (De
la Fuente et al.; McManus et al.). Specific clinical applications concerning neurorehabilitation,
gait analysis, sport, kinesiology, exoskeletons, occupational medicine, and ergonomics,
are discussed in Cappellini et al., Agostini et al., Felici and Del Vecchio, Goffredo
et al., Medved et al., Steele et al., Pilkar et al., Campanini, Cosma et al., Ranavolo
et al., and Disselhorst-Klug and Williams.
The disciplines listed are not the top branches of medicine in terms of funding and
general attention. Their impact is measured in terms of function recovered, improved
quality of life or prevented deterioration, and social costs (Ranavolo et al.; Martin
and Acosta-Sojo). These “quantities” are not easy to measure. The focus on the clinical
impact of quantitative assessments of movement and of the so called “hard sciences”
to the rehabilitation field is relatively recent (8–10).
There is general agreement that the barriers limiting the clinical use of sEMG are
cultural/educational and technical/administrative.
Cultural and Educational Barriers
The education of PTs and OTs varies considerably across countries. France offers a
1+4 year non-academic degree; some countries offer a clinical doctorate (DPT, DOT).
Proper interpretation of sEMG requires both technical and clinical competencies. Should
these two different types of expertise be merged into a single professional expert,
or in two distinct professional figures?
Some universities (TU Delft, Erasmus MC, and LUMC
1
) started training a “clinical technologist” who is a registered healthcare professional
carrying out tests and signal processing independently. This new figure has been well-received
by the local clinical community (see text footnote 1). Manca et al. indicate that,
in reply to their questionnaire, “… the professional figure of ‘human motion analyst’
was put forward by some respondents as a possible reference to manage sEMG assessments
in the clinical setting.” Some interviewees in the work of Cappellini et al. made
similar propositions.
The alternative option of integrating technical knowledge into the training of PTs,
OTs, MSs, and other health operators, finds approval but few implementation efforts.
A research group integrating clinicians from Brazil and Chile promoted a Winter School
to integrate knowledge about sEMG into the background of clinical operators (De la
Fuente et al.). Other authors propose that practical experience working with sEMG
should be embedded into education in the form of workshops or course placements to
effectively promote its use, and outline a basic tutorial which could be used as a
tool for teaching or self-guided learning (McManus et al.). A new medical degree addressing
technological issues
2
has been activated in Italy. Masters in Advanced Technologies in Rehabilitation are
currently offered by other institutions to MDs, PTs, OTs, and MSs
3
,
4
.
The need for increased technical training of clinical operators and of their educators
is generally recognized by all contributors to the project. The publication of open
access teaching material
5
, as well as tutorials and consensus papers is in this direction [(1, 2, 4, 5); Felici
and Del Vecchio]. However, freely available tutorials are still not sufficient, since
“publishing our work in journals is essential—but publication of research is not,
by itself, sufficient if our goal is to support clinical practice. People follow the
lead of other people they know and trust when they decide whether to take up an innovation
and change the way they practice!” (11). Lack of knowledge of books and journals in
the field is common.
The lack of a Ph.D. degree in Physiotherapy, preliminary to the academic training
of professors, the lack of research and publication record by PTs (12), and the poor
technical and instrumental education of operators lead to a vicious cycle that is
hard to break:
No teaching of sEMG applications→No clinical competence in the use of sEMG→Few clinical
publications and no grant requests in the field for large clinical studies on sEMG→No
experience acquired at the academic level→No academic training of qualified professors→No
teaching of sEMG applications. Conclusion: undemonstrated utility of the method.
Is the user and caregiver perspective a key untapped resource in the design, implementation,
and use of sEMG devices as indicated by Feldner et al.? Probably not for clinical
measurements but the perspective of clinical operators should be considered (13).
There is general agreement by clinicians about the potential clinical usefulness of
sEMG as shown in Table 2 in [Manca et al.; Cappellini et al.; (13)]. The interviews
carried out by these authors indicate that sEMG “provides unique information on neuromuscular
function that is not offered by other assessment techniques/tools.” Large consensus
was reached in Manca et al., among 80% to 97% of the 35 respondents interviewed as
well as among others interviewed by Cappellini et al. who found that “sEMG use was
considered to substantially enhance the quality of patient's assessment.” The slow
dissemination of this knowledge seems to be a barrier to clinical translation.
Some contradictions are linked to the fact that (as opposed to ECG) visual analysis
and interpretation of sEMG is not easy. However, improper muscle coordination and
timing (e.g., in gait analysis) can be readily detected visually. Nonetheless, the
interpretation of this information requires a thorough comprehension of biomechanics,
of the existing boundaries to movement consequent to pathology and, more generally,
several years of expertise (Manca et al.; Campanini, Cosma et al.). Lack of time seems
to be one of the main reasons behind this barrier (see the section below).
Difficult interpretation of sEMG without specific education/training was reported
by 21 out of 28 interviewees (Cappellini et al.) as well as insufficient education/practice
during refresher courses (reported by 20/28), and inadequate education and training
of PTs and MDs on sEMG (reported by 17/28). This is another vicious cycle since adequate
education, in turn, reduces time for learning and clinical application.
Technical and Administrative Barriers
Most clinical research studies involving sEMG have been carried out by engineers and
life-scientists in research centers, on small groups of 10–50 subjects. Larger clinical
trials are few because they must be carried out within health institutions where engineers
are rarely present and clinical operators may lack the competence, the support, and
the time to carry them out (Campanini, Disselhorst-Klug et al.).
This is another barrier leading to the undemonstrated utility of the method. The absence
of academic positions implies that research in physiotherapy must be carried out in
parallel with the very time demanding routine of traditional clinical procedures.
The lack of a clinical market is the cited reason for manufacturing equipment being
mostly oriented to the much smaller research market. As a consequence, clinical operators
consider sEMG technology limited to research, cumbersome to use, time-consuming, and
expensive.
Some users suggest that clinical sEMG systems should be inexpensive and simple to
use, and incorporate some intelligence for correcting errors of the user by automatically
eliminating power line interference, movement artifacts, or other problems. This raises
the following interesting question: should technology adapt, with some internal intelligence
and higher cost, to the lack of competence of the users, or should user competence
be increased so that technology can be simpler, cheaper, better managed, and controlled?
Unquestionably, there is a need for standard protocols based on extensive clinical
trials (as was done for ECG and EEG), but the initial effort of the SENIAM project
(6) and its extensions (4, 5, 14) did not trigger subsequent clinical initiatives.
Preparing guidelines and protocols requires funding, time, and active participation
of MDs, PTs, OTs, and MSs.
On another related issue, the number of publications about methodologies for sEMG
analysis is overwhelming and confusing. Twenty-four years ago Hodges and Bui (15)
tested 27 methods for determining muscle activity onset time. There are many more
today. The number of methods to monitor sEMG spectral changes is also huge, ranging
from Fourier to wavelet, and from entropy to fractal analysis. Most of these approaches
will have limited meaning to clinicians. There is a need to define a limited number
of clinically tested reliable algorithms and best practices to use with (or propose
to) trained clinical investigators. In addition, the temptation to address complex
problems, such as dynamic sEMG, have produced at least as many approaches, generating
additional confusion. Perhaps the teacher's attention should first be focused on well-tested
methods for studying relatively simple situations, such as the timing of muscle activation
during gait in well-controlled conditions (Disselhorst-Klug and Williams) along with
the contribution to clinical decision-making (Campanini, Cosma et al.). Scientific
societies should address this issue.
Lack of time seems to be a major multifaceted barrier (Feldner et al.; Martin and
Acosta-Sojo). The application and connection of electrodes is indicated as time-consuming.
This is no longer true with the use of wireless systems but knowledge about proper
electrode positioning is required to promote time saving (14, 16–18). Time is needed
for PTs, OTs, and MSs to learn and practice these techniques. Formal academic teaching
would reduce time spent in the clinical environment, but the lack of leaders/clinicians
devoted to full-time teaching and research (doctoral students, researchers, and associate/full
professors) is another main barrier.
Administrative issues are also relevant because all clinical activities are coded
and reimbursed or documented by the clinician according to such codes. Only gait analysis
is coded in a few countries. Most other sEMG-based investigations are not.
Only a few insurance companies reimburse basic sEMG examinations. Institutional stakeholders
should outline the fact that muscle assessment for proper treatment selection would
likely generate savings, rather than cost increases (Campanini, Cosma et al.).
As indicated by Martin and Acosta-Sojo “…EMG does not provide information about life-threatening
conditions, although it can provide useful information about health- or profit-threatening
conditions.”
Furthermore, in stroke patients “surface EMG would supply information for better assessment
of deficits as well as rehabilitation progress and/or efficacy” [Martin and Acosta-Sojo;
(19)]. In the (not so) long run, personalized treatment based on personalized assessment
(Campanini, Cosma et al.) would reduce the weight of ineffective therapies, increase
insurance profits, and reduce costs for national health systems.
Conclusions
Several negative factors, inconsistencies, and contradictions are outlined in the
project. On the one hand, rehabilitation clinicians; (a) recognize the value and need
for formal education to enable more rigorous and clear evidence highlighting the benefits
of sEMG; and (b) assert that the opportunities to pursue it are inadequate due to
administrative and time resource limitations. On the other hand, many textbooks (14)
and the abundant free resources available [(1, 2, 4–6); see text footnote 5
6
] are not exploited, either in schools or for continuing education. Increasing their
quantity and quality has not been as useful as expected. Vicious cycles can be broken;
(a) by extending the number of years required for a clinical degree; and (b) by opening
opportunities for higher education and research promoted by scientific associations,
the EU, and other national/international bodies.
Removing administrative obstacles is equally important to lighten the workload of
clinical operators, leaving time for applying and investigating more recent and well-documented
techniques. Doing so would promote experience-based technical improvements, prime
virtuous cycles incrementing knowledge, applications, market, and reducing the commercial
prices of devices.
Introducing new professional figures such as rehabilitation engineers or clinical
technologists (see text footnote 1), alongside clinical operators, would substantially
reduce (but would not eliminate) the need for technical training of the latter. As
rehabilitation technology is rapidly developing, such figures will become necessary
very shortly and early training of these operators is certainly appropriate. The clinical
responsibilities of these two professional figures should be defined soon. Finally,
a common language for proper communication must be available on both sides to understand
the information carried by sEMG.
Author Contributions
All authors contributed equally to the preparation of the Editorial.
Conflict of Interest
The authors declare that the research was conducted in the absence of any commercial
or financial relationships that could be construed as a potential conflict of interest.