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Effective intervention for low back pain (LBP) can include feedback in one form or other. Although extrinsic feedback (EF) can be provided in a number of ways, most research has not considered how different EF characteristics (e.g. timing and content) influence treatment outcomes. A systematic search related to feedback and LBP was performed on relevant electronic databases. This narrative review aims to describe the forms of feedback provision in the literature regarding management of LBP, and to discuss these in light of previously recommended principles for the use of extrinsic feedback. The present review found support for the provision of EF that focuses on content characteristics including program feedback, summary results feedback, and external focus of attention. Temporal characteristics should enhance the use of intermittent or self-selected feedback. The literature does not support the provision of concurrent or constant EF. As much of the literature related to EF in the management of LBP has not considered content and timing characteristics we have identified future research directions that will clarify the use of content and timing characteristics of EF relative to the management of LBP.
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Systematic Review
Extrinsic feedback and management of low back pain: A critical review of the
literature
Daniel Cury Ribeiro
a
,
*
, Gisela Sole
a
, J. Haxby Abbott
b
, Stephan Milosavljevic
a
a
Centre for Physiotherapy Research, School of Physiotherapy, University of Otago, 325 Great King Street, Dunedin 9016, New Zealand
b
Orthopaedic Surgery eMedical and Surgical Sciences, Dunedin School of Medicine, University of Otago, Dunedin, 913, New Zealand
article info
Article history:
Received 5 May 2010
Received in revised form
22 November 2010
Accepted 13 December 2010
Keywords:
Feedback
Rehabilitative ultrasound imaging
Back pain
Exercise therapy
abstract
Effective intervention for low back pain (LBP) can include feedback in one form or other. Although
extrinsic feedback (EF) can be provided in a number of ways, most research has not considered how
different EF characteristics (e.g. timing and content) inuence treatment outcomes. A systematic search
related to feedback and LBP was performed on relevant electronic databases. This narrative review aims
to describe the forms of feedback provision in the literature regarding management of LBP, and to discuss
these in light of previously recommended principles for the use of extrinsic feedback. The present review
found support for the provision of EF that focuses on content characteristics including program feedback,
summary results feedback, and external focus of attention. Temporal characteristics should enhance the
use of intermittent or self-selected feedback. The literature does not support the provision of concurrent
or constant EF. As much of the literature related to EF in the management of LBP has not considered
content and timing characteristics we have identied future research directions that will clarify the use
of content and timing characteristics of EF relative to the management of LBP.
Ó2010 Elsevier Ltd. All rights reserved.
1. Introduction
Motor control feedback can be dened as information provided
by different sensory receptors as a consequence of a movement
(Shumway-Cook and Woollacott, 2007). Such feedback informs
about the effect of actions, and is designed to help improve the
quality of adaptive responses (Schmidt and Wrisberg, 2008).
Information provided by the sensory system is called intrinsic
feedback, while the information provided via an external source
(another person or instrument) can be described as extrinsic feed-
back (EF) (or, augmented feedback) (Schmidt and Wrisberg, 2008).
Depending on the type of task, intrinsic feedback provides suf-
cient information to help execute or improve task performance.
Nonetheless, there can be situations where motor improvements
are very difcult to achieve without the support of EF (Guadagnoli
et al., 1996), such as in individuals whose intrinsic feedback is
impaired, in which case (re)learning of a task can be complex
(Herbert et al., 2008).
EF has been used by physiotherapists in the management of
patients with specic neuro-musculoskeletal conditions (Dozza
et al., 2005; Magnusson et al., 2008; Durham et al., 2009), such as
low back pain (LBP) and Parkinson disease. Different EF devices
include verbal feedback (Durham et al., 2009), visual feedback for
postural control and weight bearing symmetry (Brumagne et al.,
2008a; Hlavackova et al., 2009), audio feedback (Dozza et al.,
2005; Wong and Wong, 2008), and rehabilitative ultrasound
imaging feedback (Teyhen et al., 2005). EF is argued to enhance:
a) central nervous system facilitation of optimal sensory-motor
loops; b) patient awareness, condence and volitional control over
specic physiological processes; c) motivation; and d) reinforce-
ment for repetition of successful actions (Huang et al., 2006;
Schmidt and Wrisberg, 2008).
Patients with LBP are thought to have an impaired intrinsic
feedback system (Descarreaux et al., 2005; Panjabi, 2006;
Brumagne et al., 2008b) with an alteration in muscular response
(Sterling et al., 2001; Jacobs et al., 2009). The adverse alteration of
proprioception is thought to play an important role in the main-
tenance of symptoms and motor impairments (OSullivan et al.,
2003; Dolan and Green, 2006; Panjabi, 2006). The intrinsic feed-
back system can be altered due to disrupted paraspinal muscle
spindle input, as well as, imprecise central processing, causing
lumbar position sense decits (Brumagne et al., 2000). In addition,
partial ruptures of spinal ligaments leads to imprecise feedback
input to the central neural system, causing reduced postural
awareness and altered motor recruitment patterns (Panjabi, 2006).
*Corresponding author. University of Otago, Centre for Physiotherapy Research,
School of Physiotherapy, University of Otago, PO Box 56, Dunedin 9015, New Zea-
land. Tel.: þ64 3 479 5422, fax: þ64 3 479 8414.
E-mail address: daniel.cury.ribeiro@gmail.com (D.C. Ribeiro).
Contents lists available at ScienceDirect
Manual Therapy
journal homepage: www.elsevier.com/math
1356-689X/$ esee front matter Ó2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.math.2010.12.001
Manual Therapy xxx (2011) 1e9
Please cite this article in press as: Ribeiro DC, et al., Extrinsic feedback and management of low back pain: A critical review of the literature,
Manual Therapy (2011), doi:10.1016/j.math.2010.12.001
Examples reported in the literature are the delayed contraction of
transversus abdominis muscle in subjects with LBP (Hodges, 1999),
the localized atrophy and reduced capacity of actively recruit the
lumbar multidus muscle (Wallwork et al., 2009), as well as,
increased spinal co-contraction (Newton-John et al., 1995; Marras
et al., 2000) which increases spinal load (Marras et al., 2000). It is
considered that EF is a useful procedure that facilitates or augments
the information provided by the somato-sensory system (Henry
and Teyhen, 2007).
The successful provision of EF depends on the selection of
different features (Park et al., 2000; van Vliet and Wulf, 2006).
Characteristics of feedback (e.g. when to provide EF, what type of
information to be delivered) during motor learning have been
discussed in depth (Newell, 1976;Hebert and Landin, 1994;
McNevin et al., 1994;Smith et al., 1997; Park et al., 2000;
Guadagnoli and Lee, 2004) and its implications for rehabilitation
have been presented (Winstein and Knecht, 1990; Winstein, 1991;
McNevin et al., 2000). These characteristics have been recently
investigated during rehabilitation procedures for specic neuro-
muscular dysfunctions such as stroke (van Vliet and Wulf, 2006)
and LBP (Herbert et al., 2008). However, the studies investigating
the use of feedback towards managements of LBP are still limited
(Henry and Teyhen, 2007). The aim of this narrative review is to
describe the forms of feedback provision in the literature regarding
management of LBP, and to discuss these in light of previously
recommended principles for the use of EF.
2. Methods
The electronic search identied studies that have included the
use of EF on the management of LBP. The following databases were
used: Medline (1950eAugust 2010), CINAHL (1982eAugust 2010),
PsycINFO (1967eAugust 2010), Embase (1947 August 2010). Addi-
tional searches used the PEDro database, as well as searches of
rehabilitation journals including: Manual Therapy, Physiotherapy,
Physical Therapy, Archives of Physical Medicine and Rehabilitation,
Journal of Orthopaedic and Sports Physical Therapy (JOSPT). The
search strategy was developed in consultation with a faculty
librarian. The key words and the combination used for each data-
base are described in Table 1. In addition, reference lists of retrieved
articles were scanned for appropriate studies. Language restriction
was not imposed.
Studies were included if they involved a randomized control
trial of subjects, with or without LBP, exposed to a period of training
or treatment using feedback instruments (with or without the
addition of verbal or tactile feedback) that focused on motor
learning. Studies were excluded if they had any other study design,
were narrative or systematic reviews, if the focus of the study was
on behavioral feedback, or ergonomic training, or if it was not
related to motor training.
The quality scores for those studies were assessed by the PEDro
database (http://www.pedro.org.au). For studies not assessed by
the PEDro database, we report our quality assessment ndings
using the PEDro instrument (http://www.pedro.org.au). Two
reviewers (DCR, JHA) independently assessed each study. Differ-
ences were resolved by consensus. A third reviewer (GS) was
available to adjudicate unresolved differences.
In order to establish the recommended principles for the use of
EF, the following textbooks were reviewed (Magill, 2003;
Shumway-Cook and Woollacott, 2007; Schmidt and Wrisberg,
2008), as were published articles related to motor learning and
control. To identify these studies, an electronic search, through the
same databases previously described, was conducted and the
following key words used were: motor learning, motor control,
feedback, extrinsic feedback, knowledge of results, and knowledge
of performance.
3. Results
A total of 311 articles were found and 17 studies met the
inclusion criteria. The identication, screening, eligibility and
inclusion processes are described in Fig. 1. Main term denitions for
content and timing characteristics of feedback provision are
described in Table 2.
Study design description, as well as, main content and timing
characteristics of EF found in the studies identied through the
electronic search are outlined in Tables 3e5, respectively. From the
17 included studies, 6 studies (Henry and Westervelt, 2005; Teyhen
et al., 2005; Van et al., 2006; Worth et al., 2007; Herbert et al., 2008;
Magnusson et al., 2008) have compared use of EF with no use of EF
in the intervention regime (Table 3); their main ndings are pre-
sented in Table 6. The other 11 studies (Bush et al., 1985; Donaldson
et al., 1994; Ferreira et al., 20 07; Flor et al., 1983; Hides et al., 1996;
Newton-John et al., 1995; Niemisto et al., 2003; Nouwen, 1983;
Rasmussen-Barr et al., 2003; Stuckey et al., 1986; Vasseljen and
Fladmark, 2010) have used EF as part of treatment/motor training
management; however have not conducted a comparative effec-
tiveness study of EF. As a consequence, all comments regarding the
effectiveness of EF provision will be based on the former 6 studies.
The latter 11 studies are presented and the way EF was provided is
narratively described and compared to the recommendation
summary for EF provision. The PEDro quality assessment results are
reported in Table 3.
Before specically describing the extracted data related to the
use of EF in the management of LBP, a summary of existing
recommendations related to EF in motor learning is presented in
two domains: content feedback and timing feedback. LBP feedback
characteristics are then reviewed and compared with this summary
of existing recommendations.
4. Recommendations for the use of EF
The provision of EF can target different sensory channels (visual,
kinesthetic, and verbal knowledge of results). Sarlegna et al. (2007)
tested how adaptive control during reaching movements was
Table 1
Results for electronic databases searches.
Database Keywords Number of studies
PsycInfo (1) Back pain;
(2) Biofeedback Training;
(3) Biofeedback;
(4) Feedback;
(5) 2 or 3 or 4;
(6) 1 and 5.
39
Embase (1) Feedback system;
(2) Low back pain;
(3) Backache;
(4) 2 or 3;
(5) 1 and 4.
182
Medline (1) Low back pain;
(2) Feedback;
(3) Feedback, Sensory;
(4) Biofeedback, Psychology;
(5) 2 or 3 or 4;
(6) 1 and 5.
34
Cinahl (1) Low back pain;
(2) Feedback;
(3) Biofeedback;
(4) Extrinsic Feedback;
(5) 2 or 3 or 4;
(6) 1 and 5.
54
D.C. Ribeiro et al. / Manual Therapy xxx (2011) 1e92
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Manual Therapy (2011), doi:10.1016/j.math.2010.12.001
affected by different sensory channels and found there were no
differences in motor adaptation between the different feedback
groups. This study supports the concept that sensory-motor
adaptation is a multi-sensory exible process and its efciency
seems to be independent of a specic sensory channel (e.g. Vision,
audition, or kinesthesia) (Sarlegna et al., 2007). In spite of which
sensory channel is targeted, clinicians must therefore decide the
most effective way to provide EF for their patients.
Extrinsic feedback can be provided in two forms: knowledge of
results and knowledge of performance (Schmidt and Wrisberg,
2008). Knowledge of results informs about the outcome or
achieving the goal/target of a determined task, whereas, knowledge
of performance feedback informs about the characteristics of
a performed movement or task (Magill, 2000). The characteristics
of such EF can have positive, detrimental or null inuence on the
motor learning outcomes (Wulf et al., 1994). For this reason, before
providing EF, content and timing characteristics should be carefully
selected (Butki and Hoffman, 2003; Guadagnoli and Kohl, 2001;
Ishikura, 2005).
4.1. Content characteristics
In the present review, content characteristics are considered as
features related to the focus of intervention of the EF (program or
parameter), the way EF results are provided (summarized, aver-
aged, or error magnitude ee.g. accepting some minor faults as
a successful try), and the type of focus of attention associated with
the feedback (Table 2). Skill complexity, feedback redundancy and
subject experience have an important effect on learning outcomes
from EF (Guadagnoli and Lee, 2004; Janelle et al., 1997; Park et al.,
2000). When learning a new but easy task, EF does not necessarily
result in enhancement of learning. While learning a complex task,
provision of EF seems to enhance motor performance (Fredenburg
et al., 2001). When there is sufcient intrinsic information, EF
provision will not necessarily induce better learning outcomes
(Guadagnoli et al., 1996). In this case, it is generally accepted that
the therapist should direct and assist the subject to correctly
identify and use the available intrinsic feedback information during
task execution (Schmidt and Wrisberg, 2008). The more novel the
task and less experienced the participant; the more useful EF is
likely to be (Guadagnoli et al., 1996; Guadagnoli and Lee, 2004).
4.1.1. Program and parameter feedback
Learning a new task involves the acquisition of a generalized
motor pattern followed by the renement of specic execution
parameters (Schmidt and Wrisberg, 2008). Different types of
instruction feedback can be used to improve motor learning
during these two phases. Program feedback provides information
regarding the general movement pattern, while parameter feed-
back provides information of a specic component of the entire
movement pattern (Schmidt and Wrisberg, 2008). Both forms of
feedback can be provided prescriptively or descriptively. The
former describes errors and suggests how to correct them while
the latter only describes the errors (Schmidt and Wrisberg, 2008).
Records identified through
database searching
(n = 309)
Additional records identified
through other sources
(n = 2)
Records after duplicates removed
(n = 283)
Records screened
(n = 283)
Records excluded (n = 264):
- Not RCT, narrative
reviews, guidelines,
unrelated to motor training
of low back muscles, focus
on behavioral feedback, and
focus on lifting ergonomic
training feedback.
Full-text articles
assessed for eligibility
(n = 19)
Full-text articles excluded
with reasons (n= 2):
- Included patients with
other musculoskeletal
disorders (n = 1)
- Related to psychological
behavioural feedback
(n = 1)
Studies included in
qualitative synthesis
(n = 17)
Fig. 1. Selection process.
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Manual Therapy (2011), doi:10.1016/j.math.2010.12.001
Better results are often obtained when prescriptive feedback is
provided.
4.1.2. Amount of information during feedback provision
The quantity and precision of EF can interfere in the learning
process (Guadagnoli et al., 1996;Ishikura, 2005). Summary feed-
back, which provides information after a specic number of trials,
has shown to be superior, when compared to EF provided after
every trial (Gable et al., 1991). Average feedback provides mean
values (mean error or performance score) of a group of trials (Wulf
and Schmidt, 1996), it is considered to deteriorate movement
parameter learning (Wulf and Schmidt, 1996), but to be superior to
every trial EF. During every trial feedback, subjects ignore intrinsic
feedback information and become excessively dependent on EF
(Ranganathan and Newell, 2009a; Salmoni et al., 1984).
4.1.3. Performance bandwidth (error magnitude)
Another important issue is to determine the error magnitude
(performance bandwidth) that should be followed by feedback
(Butler et al., 1996; Lai and Shea, 1999; Smith et al., 1997). For
example, isolated contraction for lumbar multidus can be
considered as successful when no pelvic tilt is performed
concomitantly, and multidus muscle thickening can be visualized
on the rehabilitative ultrasound imaging screen (Herbert et al.,
2008). In this example, the physiotherapist might consider
a performance as successful even when small amount of pelvic tilt
movement occur simultaneously to multidus muscle contraction.
Some studies support the idea that changing the bandwidth size
during motor task trials does not alter motor outcomes (Goodwin
and Meeuwsen, 1995; Lai and Shea, 1999). Conversely, Smith
et al. (1997) found that a larger bandwidth (10%, when compared
to 0 and 5%) has been associated with better retention outcomes.
The use of bandwidth for EF provision enhances motor learning if
qualitative knowledge of results feedback is provided when motor
outcome is included within the bandwidth (Butler et al., 1996). In
other words, subjects need to be aware that non-provision of EF
means performance was considered either correct or within a pre-
determined error tolerance (Butler et al., 1996).
4.1.4. Focus of attention
EF can be applied in a form that drives learners attention to
body movement characteristics (internal focus of attention) or to
the effect of the movement (external focus of attention) (Wulf et al.,
2002). Better motor learning outcomes are related to the use of
external focus of attention (Shea and Wulf, 1999; McNevin et al.,
2000; Wulf et al., 2009). The reasons for this are unclear,
however, it seems that attempts to control the movement itself
would interfere in automatic motor control processes and, conse-
quently, lead to deteriorated outcomes (McNevin et al., 2000). The
use of an external focus of attention likely facilitates or sustains
automatic pathways of motor control and improve motor perfor-
mance (Wulf et al., 2009).
4.2. Timing characteristics
The excessive use of EF can lead to dependency and, conse-
quently, promote detrimental or null effects on learning process
(Winstein and Schmidt, 1990; Park et al., 20 00;Butki and Hoffman,
2003). Concurrent or terminal (immediate or delayed) EF, as well
as, the frequency of EF are critical features of application during
motor learning (Magill, 2003; Schmidt and Wrisberg, 2008). EF can
be provided during every trial (constant), concurrent to the task
execution, immediately after task execution or, after a period of
time following the end of the task (delayed).
4.2.1. Concurrent and terminal feedback provision
Whether to provide EF concurrent to or after task execution is
a decision to be made by the physiotherapist. Published literature
does not support the use of concurrent EF, unless there is impaired
intrinsic feedback or insufcient information intrinsic to the task
(Park et al., 2000; Magill, 2003; Ranganathan and Newell, 2009a).
This might be the case for LBP patients, who were shown to have
impaired intrinsic feedback (Newcomer et al., 2000). Otherwise,
concurrent EF has a strong negative guidance effect (Winstein et al.,
1996; Schmidt and Wulf, 1997). One possible reason might be
related to EF obliterating the use of intrinsic feedback. Learners
become dependent on EF during the acquisition phase and,
consequently, when EF is removed, subjects are not able to perform
the task correctly (Anderson et al., 2005). Even though concurrent
visual feedback has been shown to be detrimental (Wulf and
Schmidt, 1997), the provision of concurrent audio feedback is
benecial for motor learning (Konttinen et al., 2004). Concurrent
visual feedback appears to induce a different neural pathway when
compared to the execution of atask without visual EF. However, the
reasons for the better retention results from learning with audio
feedback are unclear.
Delayed EF improves motor learning outcomes (Magill, 2003;
Anderson et al., 2005). It is possible that, by delaying the feedback
provision for a few seconds or minutes after movement execution,
subjects have time to better explore their intrinsic feedback and
relate it to the motor outcome. When EF is provided, they can then
compare the intrinsic feedback information to that provided by the
EF (Anderson et al., 2005). However, the optimal delay interval for
providing EF has yet to be determined (Magill, 2003).
4.2.2. Frequency of feedback provision
Additionally, providing EF after every trial (100% EF) appears to
deteriorate motor learning, when compared to intermittent EF (e.g.
Table 2
Main term denitions for content and timing characteristics.
Content characteristics
Program feedback Feedback related to the
general pattern of movement.
Parameter feedback Feedback related to a specic
component (part) of the whole
movement pattern.
Summary feedback Feedback is pooled and
provided after a specic
number of trials.
Average feedback Feedback provided refers to mean
values (mean error or performance
score) of a group of trials.
Bandwidth
(error magnitude)
The amount of error that is
considered to distinguish between
successful and unsuccessful trials.
Internal focus of attention Feedback drives learners attention
to body movement characteristics.
External focus of attention Feedback drives learners attention
to the effect of the movement.
Timing characteristics
Concurrent feedback Feedback is provided simultaneous
to task execution.
Terminal feedback Feedback is provided after
task execution.
Immediate Feedback is provided immediately
after task execution;
Delayed Feedback provision is delayed
after the end of the task execution.
Frequency
Constant Feedback is provided at every trial.
Reduced Feedback is provided for a fraction
of trials (e.g. 30%).
Self controlled Feedback provision depends on
learners decision.
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50%, 20% or 10% EF) (Salmoni et al., 1984; Winstein and Schmidt,
1990; Weeks and Kordus, 1998; Park et al., 2000). Weeks and
Kordus (1998) found that uninjured learners, who received 33%
relative frequency of knowledge of performance feedback, per-
formed better when compared to 100% relative EF during a soccer
throw-in task. The authors suggested that reduced frequency
Table 3
Study description.
Author (Year) Population Intervention Nature of EF
(KP or KR)
Type
of EF
Instrument/
Principle
PEDro
Score
Vasseljen and Fladmark,
2010
109 chronic LBP
patients
8-week intervention (8 sessions) G1:
Low load exercise (stabilization focused on
transverses abdominis) with USI ;G2:
High load exercise; G3: General exercise.
KP Visual USI 6/10
a
Magnusson et al. (2008) 26 LBP patients 5-week intervention (10 sessions) G1:
Conventional physiotherapy; G2:
Conventional
physiotherapy + biofeedback
KP Visual, auditory,
success rates, reports
Postural 3/10
b
Herbert et al. (2008) 30 healthy
participants
4-week intervention (8 sessions):
multidus muscle exercise G1: constant
USI;
G2: variable USI
KR (verbal)
KP (visual)
Visual
Verbal
USI 5/10
a
Ferreira et al. (2007) 240 chronic
LBP patients
8-week intervention (12 sessions) G1:
General exercise; G2: Motor control
exercise + USI; G3: Manipulative therapy
KP Visual USI 8/10
b
Worth et al. (2007) 19 LBP patients Teaching abdominal hollowing exercise
and retention test after 4 days. G1verbal
and palpatory feedback; G2: USI
KP Visual USI 5/10
b
Van et al. (2006) 25 healthy subjects Teaching isometric contraction of
multidus
muscle. G1: Knowledge of results; G2:
Knowledge of results and performance.
KR (amount of
increase
in muscle thickness)
and
KP (visual observation
of muscle contraction)
Visual, report USI 4/10
a
Teyhen et al. (2005) 30 LBP patients G1: lumbar stabilization exercise; G2:
lumbar stabilization exercise + USI; Both
groups received 1 session followed
short-term re-assessment (3 min after
session).
Retention test was carried out after 4 days
(all patients received home exercises).
KP Visual USI 7/10
b
Henry and Westervelt
(2005)
48 healthy
participants
Teaching abdominal hollowing exercise
and
retention test after 4 days. G1: minimal
verbal
feedback; G2: verbal and palpatory
feedback;
G3: verbal, palpatory and USI
KP Verbal, tactile
and visual
USI 6/10
a
Rasmussen-Barr et al.
(2003)
47 LBP patients 6-week treatment (one session/week).
G1: Stabilizing group (PBU);
G2: Manual treatment group
KP Pressure PBU 5/10
b
Niemisto et al. (2003) 240 LBP patients 4-week intervention (one session/week).
G1: Manipulation and stabilizing exercise
(abdominal drawing-in maneuver);
G2: Physician consultation
KP and KR Pressure, visual and
tactile
PBU 8/10
b
Hides et al. (1996) 39 LBP patients 4-week intervention G1: Medical
management; G2: Medical management
and stabilization exercises
KP Visual USI 7/10
b
Newton-John et al. (1995) 44 LBP patients 8-week intervention (2x/week).
G1: Cognitive behavior therapy;
G2: EMG Biofeedback; G3: Wait list control
KP Not adressed EMG 3/10
b
Donaldson et al. (1994) 36 chronic LBP G1: EMG Biofeedback, G2: Relaxation;
G3: Education
Not adressed Not adressed EMG 5/10
b
Stuckey et al. (1986) 24 chronic LBP 8 sessions (45 min each) G1: EMG
feedback;
G2: Relaxation training; G3: Placebo
condition
KP Visual and auditory EMG 4/10
b
Bush et al. (1985) 72 chronic LBP 8 sessions (period of intervention unclear)
G1: Paraspinal EMG feedback; G2: Placebo;
G3: No intervention
KP Auditory EMG 4/10
b
Nouwen (1983) 20 LBP patients 3-week intervention (5x/week). G1: EMG
Biofeedback; G2: Wait list control
KP Visual and auditory EMG 5/10
b
Flor et al. (1983) 24 chronic LBP G1: EMG feedback; G2: Pseudo therapy;
G3: Conventional medical treatment
KP Auditory EMG 4/10
b
G1: group 1; G2: group 2; G3: group 3; EF ¼extrinsic feedback; KP ¼knowledge of performance; KR ¼knowledge of results; PBU ¼pressure biofeedback unit; USI -
¼ultrasound imaging; EMG ¼electromyopgrahic feedback.
a
PEDro score assessed by the authors.
b
PEDro score reported from www.pedro.org.au.
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eliminates learners dependence on the provision of EF (Weeks and
Kordus, 1998). A possible explanation for reduced retention with
100% EF is that EF is a guide for motor execution and learners
cannot guide themselves appropriately by task-intrinsic feedback
when it is removed (Salmoni et al., 1984; Winstein et al., 1994;
Anderson et al., 2005; Ranganathan and Newell, 2009).
Better outcomes were found if the decision for receiving feed-
back was controlled by the learner (Chiviacowsky and Wulf, 2002,
2005). Self-controlled feedback tends to be requested after
performances learners believed to be successful (Chiviacowsky and
Wulf, 2002, 2005, 2007). The reason why learners ask for EF after
good trials and why it is more effective than a rigid schedule of
feedback is unclear (Chiviacowsky and Wulf, 2002). However,
recent results point to motivation, where knowledge about
successful trials induces learners to reproduce the successful motor
pattern (Chiviacowsky and Wulf, 2002, 2007). These ndings
indicate that providing feedback after good trials is superior than
after incorrect trials, nonetheless, it is uncertain whether it can be
applied to different motor tasks (Chiviacowsky and Wulf, 2007).
5. Feedback provision for the management of LBP
Different types of EF have been used during management of LBP
using various conceptual frameworks (Table 3). Positive results
from these studies are likely related to sensory-motor adaptation
occurring independently of type of EF. Even though, the selection of
optimal content and timing characteristics might inuence motor
adaptation. The provision of EF in the management of LBP is dis-
cussed in light of previously described principles for the use of EF.
5.1. Content characteristics
5.1.1. Program and parameter feedback
One study (Magnusson et al., 2008) provided program feedback,
while all other studies focused on parameter feedback (Table 4).
The reason may be that therapists believe that LBP patients need to
improve specic features of movement patterns in order to
enhance the quality of such performed movements. Examples
reported in the literature, where parameter feedback was used,
include delayed contraction of transversus abdominis muscle
(Hodges, 1999), localized atrophy and reduced capacity to actively
recruit the lumbar multidus muscle (Wallwork et al., 2009), as
well as, increased amount of spinal co-contraction (Flor and
Birbaumer, 1993; Newton-John et al., 1995; Marras et al., 2000)
increasing spinal loads (Marras et al., 2000). Nonetheless, it is
considered that motor program training and, consequently,
program feedback can enhance neural reorganization and motor
control (Shepherd, 2001; van Vliet and Heneghan, 2006). Since
motor control acquisition is task-specic, the isolated training of
a component of the movement might not be as useful as the
training of the functional task itself (Shepherd, 2001; van Vliet and
Heneghan, 2006; Shumway-Cook and Woollacott, 2007).
5.1.2. Amount of information during feedback provision
Two studies have provided summary EF (Herbert et al., 2008;
Magnusson et al., 2008). In addition, Herbert et al. (2008) results
support the provision of variable feedback schedule for improve-
ment of multidus muscle recruitment. The literature supports the
provision of summary EF for motor learning, indicating that it has
a better inuence on acquisition of a motor skill compared to EF
provided at the end of every trial (Schmidt et al., 1990; Guadagnoli
et al., 1996). However, other research suggests that there is an
optimal number of performance attempts prior to provision of
summary feedback (Schmidt et al., 1990). Theoretically, as the
complexity of the task is increased, the number of trials to be
included in the summary feedback is reduced (and consequently,
the frequency of feedback is increased) (Guadagnoli and Lee, 2004;
Schmidt and Wrisberg, 2008). Task difculty will be related to
personal previous motor experience and the task itself (Guadagnoli
and Lee, 2004). However, for subjects with LBP, it is important to
consider the disruption magnitude of the intrinsic feedback system
(OSullivan et al., 2003; Brumagne et al., 2008b), since subjects with
increased proprioceptive disruption might benet from more
frequent EF. Nonetheless, this has not been investigated in the LBP
population.
5.1.3. Performance bandwidth (error magnitude)
Two studies (Henry and Westervelt, 2005; Magnusson et al.,
2008) have used performance bandwidth during training of
abdominal hollowing maneuvers in healthy subjects (Henry and
Westervelt, 2005) and during rehabilitation program for LBP
(Magnusson et al., 2008). The former has used it for the control
group and the latter used it as a form of progression for reha-
bilitation spinal exercises. None of these studies have assessed
the effect of different bandwidth magnitudes on clinical
outcomes.
Table 4
Content characteristics.
Content Characteristics
Author (Year) Program Parameter Summary Average Bandwidth Focus of attention (Internal or External)
Vasseljen and Fladmark, 2010 No Yes No No No Not addressed
Magnusson et al. (2008) Yes Yes Yes No Yes External
Herbert et al. (2008) No Yes Yes (VAR group) No No Not addressed
Ferreira et al. (2007) No Yes No No No Not addressed
Worth et al. (2007) No Yes No No No Not addressed
Van et al. (2006) No Yes Yes No No Not clear (G1); External (for G2)
Teyhen et al. (2005) No Yes No No No Not addressed
Henry and Westervelt (2005) No Yes No No Yes (Control) Not addressed
Rasmussen-Barr et al. (2003) No Yes No No No Not addressed
Niemisto et al. (2003) No Yes No No No Not addressed
Hides et al. (1996) No Yes No No No Not addressed
Newton-John et al. (1995) No Yes No No No Not addressed
Donaldson et al. (1994) No Yes Not adressed Not adressed Not adressed Not adressed
Stuckey et al. (1986) No Yes No No No External
Bush et al. (1985) No Yes No No No Not addressed
Nouwen (1983) No Yes No No No Not addressed
Flor et al. (1983) No Yes No No No Not addressed
VAR ¼variable provision of EF group; CON ¼constant provision of EF group.
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5.1.4. Focus of attention
The use of external focus of attention on motor learning in
patients with LBP has not been compared to internal focus of
attention. Literature from the motor learning eld suggests that EF
should be provided with an external focus of attention (Shea and
Wulf, 1999; Wulf et al., 2009). Similar results were found for
subjects with Parkinson disease (Wulf et al., 2009), who presented
a reduction on postural instability when instructed to perform
a task with an external focus of attention.
Magnusson et al. (2008) used an external focus of attention in
their trial of LBP treatment while Van et al. (2006) used external
focus of attention in healthy subjects during isometric contraction
of multidus muscle. Their ndings support the use of EF as an
additional tool for rehabilitation of LBP and training of multidus
muscle contraction. However, other studies do not support better
learning or clinical outcomes from using EF (Henry and Westervelt,
2005; Teyhen et al., 2005; Worth et al., 2007; Herbert et al., 2008).
These four studies (Henry and Westervelt, 2005; Teyhen et al.,
2005; Worth et al., 2007; Herbert et al., 2008) provided visual
feedback to subjects and it is not clear what type of focus of
attention was provided. The different ndings between those of
Van et al. (2006) and Worth et al. (2007) might be related, at least
partially, to the type of focus of attention used. While results by Van
et al. (2006) support the provision of EF (even during the retention
test, the EF group performed better), Worth et al. (2007) found the
feedback group performed better only during immediate assess-
ment. At the retention test, no difference was found between
groups (Table 6).
5.2. Timing characteristics
5.2.1. Concurrent and terminal feedback provision
Rehabilitative ultrasound imaging (visual EF) has been used to
enhance contraction of transversus abdominis (Worth et al., 2007).
However, Henry and Westervelt (2005) and Teyhen et al. (2005)
found provision of rehabilitative ultrasound imaging (visual EF)
did not enhance the ability to perform the abdominal drawing-in
maneuvre (Table 6). Although different explanations are presented
by the authors (Henry and Westervelt, 2005; Teyhen et al., 2005), it
is possible that the use of concurrent visual feedback inuenced the
results. On the other hand, the ndings from Van et al. (2006)
support the provision of concurrent feedback (Table 6). Due to
the conicting evidence, it is clear more research is needed to
clarify this topic.
5.2.2. Frequency of feedback provision
Only one study tested how frequency of EF affected motor
learning in LBP (Herbert et al., 2008) and found reduced EF
frequency is better for motor learning purposes (Table 6). In the
present review, rehabilitative ultrasound imaging feedback was
considered as a form of parameter feedback (Table 2), aiming to
improve the control over specic muscles (generally multidus or
transversus abdominis), instead of providing information about the
general movement pattern. Interestingly, the ndings from Herbert
et al. (2008) are in contrast with other authors (Salmoni et al., 1984;
Winstein and Schmidt, 1990; Weeks and Kordus, 1998; Park et al.,
2000). Herbert et al. (2008) found reduction of EF frequency to be
useful for acquisition of parameters of fundamental pattern of
movement. Nonetheless, reduced frequency of EF appears to have
only a small inuence on the parameters of the fundamental
Table 5
Timing characteristics
Author Concurrent Terminal Frequency
(Year) Immediate Delayed Constant Reduced frequency Self-controlled
Vasseljen and Fladmark, 2010 Yes Not clear Not clear Not clear No No
Magnusson et al. (2008) Yes Yes No Yes No No
Herbert et al. (2008) Yes (CON group) Yes (CON group) Yes (VAR group) Yes (CON group) Yes (VAR group) No
Ferreira et al. (2007) Yes No No Yes No No
Worth et al. (2007) No Yes No Yes No No
Van et al. (2006) Yes (G2) Yes (G1) No Yes No No
Teyhen et al. (2005) Yes No No Yes No No
Henry and Westervelt (2005) Yes (verbal & visual) Not clear Not clear Yes No No
Rasmussen-Barr et al. (2003) Yes No No Yes No No
Niemisto et al. (2003) Yes No No Yes No No
Hides et al. (1996) Yes Not clear Not clear Yes No No
Newton-John et al. (1995) Not addressed No No Not addressed Not addressed Not addressed
Donaldson et al. (1994) Yes Not addressed Not addressed Not addressed Not addressed Not addressed
Stuckey et al. (1986) Yes No No Yes No No
Bush et al. (1985) Yes No No Yes No No
Nouwen (1983) Yes No No Yes No No
Flor et al. (1983) Yes No No Yes No No
VAR ¼variable provision of EF group; CON ¼constant provision of EF group.
Table 6
Main ndings for studies that compared the use or not of extrinsic feedback on
training or rehabilitation management.
Author (year) Main ndings
Magnusson et al.
(2008)
Patients allocated in the feedback group presented
enhanced scores for VAS, SF-36 and kinematic measures.
Herbert et al. (2008) Variable feedback provision resulted in better multidus
muscle recruitment, when compared to constant feedback
provision. During the retention test, the variable feedback
group also performed better.
Worth et al. (2007) The provision of ultrasound imaging improved short-term
performance for abdominal hollowing exercise,
nonetheless, retention test results demonstrated no
differences between the two groups.
Van et al. (2006) Participants that received ultrasound imaging feedback
improved motor recruitment for multidus muscle and,
also, performed better during retention test.
Teyhen et al. (2005) Adding feedback did not improve contraction of
transverses abdominis muscle. One possible reason could
be insufcient training period.
Henry and
Westervelt
(2005)
The use of ultrasound imaging improved short-term
performance for lumbar stabilization exercise (specic
contraction for transverses abdominis). However,
retention test results demonstrated no differences
between the three feedback groups.
VAS ¼visual analogue scale; SF-36 ¼short form (SF) e36 questionnaire.
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pattern of movement (e.g. movement time, amplitude, speed),
when motor learning related to manual tasks, such as striking keys
in a board, was analyzed (Lai and Shea, 1998, 1999; Schmidt, 2003).
Although this consideration is only based on the results of one
study related to LBP (Herbert et al., 2008), further questions
include: how does pain experience, in subjects with LBP, inuence
motivations and patterns of neural processing, when compared to
healthy participants, when (re)learning a task?; and how does
adaptive reorganization of motor cortex (Tsao et al., 2008),
considered to be present in LBP subjects, inuence motor learning?
Magnusson et al. (2008) provided constant EF during the
intervention period. Even though that is argued to have a detri-
mental effect on motor learning (Lai and Shea, 1999), their results
were favourable for the use of EF. It is important to highlight that
the authors provided EF with the following recommended char-
acteristics: program and parameter feedback, an external focus of
attention, and summary feedback. It is possible that these charac-
teristics have prevailed over the negative effect of providing
constant EF. Moreover, the authors have used three different types
of EF: visual, auditory and success rates reports, as well as, variable
bandwidth (with increase in bandwidth precision as treatment
progressed). Thus the use of bandwidth seems to be useful when
followed by some form of instructional feedback (Butler et al.,
1996).
Six studies (Flor et al., 1983; Nouwen, 1983; Bush et al., 1985;
Stuckey et al., 1986; Donaldson et al., 1994; Newton-John et al.,
1995) have used the painetensionepain cycle as the theoretical
framework to support the use of electromyographic feedback for
LBP (Table 3). Nonetheless, other recent conceptual pain models
have been proposed and, it is clear that pain experience has a more
complex interaction with motor control response (Hodges and
Moseley, 2003; Moseley, 2003; Arendt-Nielsen and Graven-
Nielsen, 2008). No studies were found that investigated the use
of electromyographic feedback to improve specic muscle
recruitment for individuals with LBP.
There are other types of feedback commonly used by manual
therapists that were not included in the present review. One
example is the use of adhesive medical tape (Selkowitz et al., 2007;
Greig et al., 2008) as a feedback tool for rehabilitation. If tape is
used with the aim of augmenting the intrinsic feedback, then, the
same principles described above could be considered.
5.2.3. Future research directions
We found no evidence for a number of areas related to LBP and
EF. Whether there are differences between knowledge of perfor-
mance or knowledge of results EF on LBP outcomes; as well as, how
parameter or program EF, different focus of attention, immediate or
delayed terminal feedback and self-controlled EF inuence LBP
outcomes still need to be claried.
Considering the signicant and clinically relevant outcomes
presented by Magnusson et al. (2008), the use of postural feedback
requires further exploration. The way in which postural feedback
inuences motor control in subjects with LBP needs to be identied.
Finally, it is possible that different LBP clinical presentations will
respond in different ways to the provision of EF in its various forms.
This is an area that has considerable scope for research where
clarication of optimal responses has important clinical promise.
Additionally, we suggest that future research could, also, investigate
the use of electromyographic feedback in LBP rehabilitation.
6. Implications for clinical practice
Physiotherapists should consider the strong inuence that
feedback can have on motor learning as well as rehabilitation
outcomes. Since the literature related to LBP and EF still needs to
explore a number aspects related to optimal EF delivery, recom-
mendations are based on the available literature primarily related
to the motor learning eld, which has focused mainly in healthy
subjects. Generally speaking, physiotherapists should provide EF
with the following content characteristics: program feedback,
summary results feedback, and external focus of attention. With
regards to timing characteristics, concurrent and constant feedback
should be avoided. Reduced frequency or self-selected feedback has
stronger support and should be provided.
Acknowledgments
Support was provided by the University of Otago (PhD Schol-
arship). The authors would like to thank Mr. Richard German
(Faculty Librarian) in assisting with the electronic search strategy
for this study.
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D.C. Ribeiro et al. / Manual Therapy xxx (2011) 1e99
Please cite this article in press as: Ribeiro DC, et al., Extrinsic feedback and management of low back pain: A critical review of the literature,
Manual Therapy (2011), doi:10.1016/j.math.2010.12.001
... In addition, the timing of feedback varies from terminal feedback, which is provided after a task sequence, to concurrent (realtime) feedback, which is provided directly (concurrent to) when certain preset threshold levels are exceeded. Augmented feedback has been used in a wide range of application areas such as sports (Galloway 2011, Kos and Umek 2018), rehabilitation (Ribeiro et al. 2011, Araujo et al. 2017, Wang et al. 2017, computer work (Madeleine et al. 2006, de Korte et al. 2008, surveillance operations (Bazazan et al. 2019) and manual handling (Vignais et al. 2013, Lind et al. 2020c, Kamachi et al. 2021. ...
... In a systematic literature review, Ribeiro et al. (2011) found support for the effectiveness of augmented feedback in the prevention of low back pain (LBP), whilst there are still single studies reporting no significant effects on reducing MSDs prevalence (Meijer et al. 2009) or discomfort (de Korte et al. 2008). Several studies indicate that posturecorrection feedback (error amplification feedback), i.e., which provide feedback signals to the operator when performing undesired movements, can be effective to induce motor learning (Sigrist et al. 2013, Liu et al. 2018) especially among skilled users (Milot et al. 2010, Sigrist et al. 2013. ...
... Several studies indicate that posturecorrection feedback (error amplification feedback), i.e., which provide feedback signals to the operator when performing undesired movements, can be effective to induce motor learning (Sigrist et al. 2013, Liu et al. 2018) especially among skilled users (Milot et al. 2010, Sigrist et al. 2013. However, concurrent correction feedback may hamper the body´s intrinsic feedback system, and can reinforce feedback dependence if provided too often or for too long (Lam et al. 2011, Ribeiro et al. 2011, Buchanan and Wang 2012, Patterson et al. 2013. Doss et al. (2018) studied the combined effect of verbal feedback and concurrent posture-correction audio feedback in three different types of simulated patient transfer tasks. ...
Article
Vibrotactile feedback training may be used as a complementary strategy to reduce time in demanding postures in manual handling. This study evaluated the short- and medium-term effects of concurrent posture-correction vibrotactile feedback training on trunk inclination exposure in real manual sorting work. Fifteen warehouse workers completed the training and the follow-up sessions. Trunk inclination angles were recorded using the ambulatory Smart Workwear System. Questionnaires were used for assessing system usability, perceived physical exertion and work ability. The results showed reduced time in trunk inclination >30°, >45° and >60°, and reductions in the 90th, 95th and 99th percentile trunk inclination angles, when receiving feedback and immediately after feedback withdrawal. No significant reduction was retained after one and three weeks. The wearer comfort was scored high, and the feedback did not increase the perceived cognitive demands. No significant effects attributed to changed trunk inclination exposure were observed for perceived physical exertion or work ability. The training program has the potential of contributing to reduced trunk inclination exposure in the short-term. Future studies are needed to evaluate if improvements of the feedback training can transfer the short-term results to retained median- and long-term effects.Practitioner Summary: A two-day training program with concurrent posture-correction vibrotactile feedback can contribute to reduced exposure of trunk inclination in real manual sorting work in the short term. More research is needed on how to design the feedback training programs in order to be effective in the long term.
... Most of the literature assessing how different characteristics of EF impact on motor control and learning involved mainly on asymptomatic individuals (Chiviacowsky and Wulf, 2002;Gentile, 1998;Lametti and Watkins, 2016;Schmidt and Wrisberg, 2008;Scholl Schell et al., 2020;Wulf and Lewthwaite, 2016). According to those studies, some EF characteristics can help improve motor learning and while other characteristics can hinder motor learning (Ribeiro, Sole, Abbott, and Milosavljevic, 2011b). For example, feedback provided with summarized results, with external focus of attention, intermittent, delayed, and with reduced or self-controlled frequency led to better outcomes compared to feedback with internal focus of attention, provided constantly and concurrently (Chiviacowsky and Wulf, 2002;Henry and Teyhen, 2007;Herbert, Heiss, and Basso, 2008;Milosavljevic, 2011a, 2011b;van Vliet and Wulf, 2006;Wulf, 2013;Wulf and Lewthwaite, 2016). ...
... This makes it harder to assess the impact of different EF characteristics on clinical outcomes. Two systematic reviews reported that included studies did not adequately report the characteristics of EF used in studies assessing its effectiveness in the management of patients with neck or lower back pain (Araujo, Scholl Schell, and Ribeiro, 2017;Ribeiro, Sole, Abbott, and Milosavljevic, 2011b). Given the small number of studies exploring how different characteristics of EF impact clinical outcomes, physical therapists possibly lack knowledge about the different characteristics and their possible influence on clinical outcomes. ...
... However, the timing characteristics used by participants were not in agreement with the best evidence from the literature. For example, constant feedback delivery during exercises is not recommended (Chiviacowsky and Wulf, 2002;Henry and Teyhen, 2007;Ribeiro, Sole, Abbott, and Milosavljevic, 2011b). Few participants performed retention tests following intervention. ...
Article
Objectives This study aimed to identify the knowledge about the different characteristics of and the use of extrinsic feedback (EF) by Brazilian physical therapists. Methods This is a cross-sectional study, and we used an internet-based survey with questions about knowledge and application of extrinsic feedback in clinical practice. We analyzed the responses in relation to the best available evidence on motor control and learning. We recruited Brazilian registered physical therapists from different regions in Brazil. Participants’ demographics and survey responses were analyzed using descriptive statistics. Results Two hundred and forty-six Brazilian physical therapists participated in the study. Most participants affirmed not knowing the definition of EF (55.69%), confirmed using some form of EF in their clinical practice (86.59%), and reported using it in 50% to 90% of their patients (26.42%). Brazilian physical therapists reported using mainly summary feedback (69.10%) with external focus of attention (63.41%). Participants reported using concurrent feedback (82.83%) and delivered it after every exercise repetition (63.82%). Most participants (43.09%) did not assess learning retention. Answers were similar regardless of education level or time from graduation. Conclusions The results of this survey suggest that Brazilian physical therapists do not have sufficient knowledge about the different characteristics of EF; however, they do consider EF useful and use it for most of their patients. Brazilian physical therapists adopted adequate content characteristics of EF but not adequate use of timing characteristics of EF.
... The most common multimodal feedback interaction was auditory and visual [71,74,75]. Most studies applied concurrent bandwidth feedback [67,69,73,[75][76][77]79,80] (i.e., a feedback prompt when a movement variable exceeds a pre-determined set-point (feedback trigger) during the activity/task [131,132]; and in conjunction with a pre-determined time period [68,71,72,74,78] (Table 4); the remaining studies used terminal bandwidth feedback (feedback post-activity) [70] and summary feedback in addition to visual, auditory and vibrotactile feedback [74]. ...
... In other sectors of health research, the retention of learned movement behaviour from WIST was shown for arm-hand movement in stroke rehabilitation [43,150] and lower limb running biomechanics [44]. Previous research on the retention of skills following feedback has indicated that a fading schedule of feedback is most effective for motor-relearning and for learned skills to be retained, suggesting that gradually reducing the dependence on external feedback improved the intrinsic feedback mechanisms and subsequent motor re-learning to occur [44,132,151]. Though, the retention of skills following feedback is seldom evaluated [146]; hence, further post-evaluation research is required. ...
... Analogous to improvements in posture or movement behaviour, the likelihood of retaining learnt behaviour to reduce pain appears to be dependent on longer periods of feedback interaction. However, extrinsic feedback dependency may arise from a longer duration of concurrent feedback dominance, causing the user to be less responsive their body's own internal or intrinsic feedback mechanisms [132]. Hence, WIST feedback latency during rehabilitation studies must be considered. ...
Article
Full-text available
Background: Wearable inertial sensor technology (WIST) systems provide feedback, aiming to modify aberrant postures and movements. The literature on the effects of feedback from WIST during work or work-related activities has not been previously summarised. This review examines the effectiveness of feedback on upper body kinematics during work or work-related activities, along with the wearability and a quantification of the kinematics of the related device. Methods: The Cinahl, Cochrane, Embase, Medline, Scopus, Sportdiscus and Google Scholar databases were searched, including reports from January 2005 to July 2021. The included studies were summarised descriptively and the evidence was assessed. Results: Fourteen included studies demonstrated a ‘limited’ level of evidence supporting posture and/or movement behaviour improvements using WIST feedback, with no improvements in pain. One study assessed wearability and another two investigated comfort. Studies used tri-axial accelerometers or IMU integration (n = 5 studies). Visual and/or vibrotactile feedback was mostly used. Most studies had a risk of bias, lacked detail for methodological reproducibility and displayed inconsistent reporting of sensor technology, with validation provided only in one study. Thus, we have proposed a minimum ‘Technology and Design Checklist’ for reporting. Conclusions: Our findings suggest that WIST may improve posture, though not pain; however, the quality of the studies limits the strength of this conclusion. Wearability evaluations are needed for the translation of WIST outcomes. Minimum reporting standards for WIST should be followed to ensure methodological reproducibility.
... Two systematic reviews reported that different types of digital feedback, for instance, from electromyography [11,23] or ultrasound data [23], on muscle activity have been investigated more frequently for their use in exercising interventions for LBP than postural feedback from digital tools. Some studies have already investigated exercise interventions on postural feedback on trunk movements in clinical settings in people with LBP [24][25][26][27]. ...
... Two systematic reviews reported that different types of digital feedback, for instance, from electromyography [11,23] or ultrasound data [23], on muscle activity have been investigated more frequently for their use in exercising interventions for LBP than postural feedback from digital tools. Some studies have already investigated exercise interventions on postural feedback on trunk movements in clinical settings in people with LBP [24][25][26][27]. ...
... The use of movement feedback from wearable sensors in exercise interventions is a promising approach to improve interventions. The detailed properties of the feedback given are likely to have an impact on the success of an intervention [22,23]. Continuous feedback received during a task performance is generally seen as disadvantageous for learning [22,23]. ...
Article
Full-text available
Background: Physical exercise is a common treatment for people with low back pain (LBP). Wearable sensors that provide feedback on body movements and posture during exercise may enhance postural balance and motor control in people with LBP. Objective: This study aims to investigate whether physical exercising with postural feedback (EPF) improves postural balance, motor control, and patient-reported outcomes in people with LBP. Methods: The study was an assessor-blinded 2×2 factorial trial. We planned to recruit 80 participants with nonspecific LBP who did not receive treatment for LBP. In addition, we aimed to recruit 40 patients with chronic, nonspecific LBP who were receiving exercise therapy (ET) at the University Hospital Zurich. Both ET patients and participants without treatment were randomized to receive either an additional EPF intervention or no additional intervention. This resulted in four different combinations of interventions: ET+EPF, ET, EPF, and no intervention. The participants underwent outcome assessments at inclusion (T1); 3 weeks later, at randomization (T2); after an intervention period of 3 weeks with a predefined exercise schedule for participants receiving EPF (T3); and after an additional 6 weeks, during which participants assigned to the EPF groups could exercise as much as they wished (T4). Patients receiving ET completed their regularly prescribed therapies during the study period. Balance was assessed during quiet standing on a force platform, and motor control was assessed during a lifting task and a waiter’s bow task. Physical activity was recorded using an activity tracker and the participants’ mobile phones during the study. The predefined EPF schedule consisted of nine sessions of 20 minutes of exercise with a tablet and inertial measurement unit sensors at home. Participants performed a series of trunk and hip movements and received feedback on their movements in a gamified environment displayed on the tablet. Results: The first participant was recruited in May 2019. Data collection was completed in October 2020, with 3 patients and 32 eligible people without therapy who passed the eligibility check. Conclusions: Although it will not be possible to investigate differences in patients and people without other therapies, we expect this pilot study to provide insights into the potential of EPF to improve balance in people with LBP and adherence to such interventions.
... One is to convey the current exposure level (real-time exposure level) via concurrent (real-time) feedback. The other way is accumulated exposure level (using terminal feedback [72]), which is derived from a longer measurement period, ranging from minutes to hours, depending on the application. Depending on the need, different types of feedback modalities can be provided, such as visual on a screen, auditory through earphones, or tactile via haptic actuators [41]. ...
... The chosen feedback modality (i.e., concurrent feedback) is intended for short training periods of about 10-30 min. For longer training periods, other feedback modalities should be considered, such as terminal feedback where the feedback is provided after task execution [72]. While this application uses haptic feedback as a strategy to mimic and augment intrinsic signals of discomfort or pain, other feedback modalities might be suitable, such as visual or auditory feedback [41]. ...
... Alternatively, augmentation of sound work techniques strategies could have been used. As previous studies have concluded, the use of both concurrent feedback and error augmentation may be less efficient when feedback is provided for longer time periods and may increase the risk of inhibiting the wearer from responding to cues provided by the body´s intrinsic feedback system [72]. This might also result in extrinsic feedback dependency [88][89][90]. ...
Article
Full-text available
Work-related musculoskeletal disorders are a major concern globally affecting societies, companies, and individuals. To address this, a new sensor-based system is presented: the Smart Workwear System, aimed at facilitating preventive measures by supporting risk assessments, work design, and work technique training. The system has a module-based platform that enables flexibility of sensor-type utilization, depending on the specific application. A module of the Smart Workwear System that utilizes haptic feedback for work technique training is further presented and evaluated in simulated mail sorting on sixteen novice participants for its potential to reduce adverse arm movements and postures in repetitive manual handling. Upper-arm postures were recorded, using an inertial measurement unit (IMU), perceived pain/discomfort with the Borg CR10-scale, and user experience with a semi-structured interview. This study shows that the use of haptic feedback for work technique training has the potential to significantly reduce the time in adverse upper-arm postures after short periods of training. The haptic feedback was experienced positive and usable by the participants and was effective in supporting learning of how to improve postures and movements. It is concluded that this type of sensorized system, using haptic feedback training, is promising for the future, especially when organizations are introducing newly employed staff, when teaching ergonomics to employees in physically demanding jobs, and when performing ergonomics interventions.
... Extrinsic feedback (or augmented feedback) is an extremely relevant topic when looking at movement enhancement strategies. Extrinsic feedback is defined as any feedback source that is given besides intrinsic feedback (Ribeiro, Sole, Abbott, & Milosavljevic, 2011;Robert, Sambasivan, & Levin, 2017;Schmidt & Wrisberg, 2008). Different external feedback strategies may enhance or diminish one's ability to learn a new task or improve the execution skilled movement (de Araujo, Scholl Schell, & Ribeiro, 2017;Ribeiro et al., 2011;Wulf & Lewthwaite, 2016) including focus of attention. ...
... Extrinsic feedback is defined as any feedback source that is given besides intrinsic feedback (Ribeiro, Sole, Abbott, & Milosavljevic, 2011;Robert, Sambasivan, & Levin, 2017;Schmidt & Wrisberg, 2008). Different external feedback strategies may enhance or diminish one's ability to learn a new task or improve the execution skilled movement (de Araujo, Scholl Schell, & Ribeiro, 2017;Ribeiro et al., 2011;Wulf & Lewthwaite, 2016) including focus of attention. Focus of attention is one of the most important strategies to provide external feedback during movement cueing (Wulf, 2013;Wulf & Lewthwaite, 2016). ...
... Focus of attention is one of the most important strategies to provide external feedback during movement cueing (Wulf, 2013;Wulf & Lewthwaite, 2016). Focus of attention is usually divided in internal focus of attention (IF), when the focus is on the body components, or external focus of attention (EF), when the focus in on environmental effect of the movement (Ribeiro et al., 2011). ...
Article
Objective To evaluate the effects of three different foci of attention (internal, external and mixed) on motor learning using craniocervical flexion test in inexperienced participants. Methods Ninety healthy young adults, with no experience in the task, practiced the craniocervical flexion test under three different focus of attention: a) Mixed Focus (internal plus external), b) Internal Focus, and c) External Focus. We assessed immediate, post-training, and retention (one week after the last training session) aspects of motor learning by quantifying (i) the activity of the superficial cervical flexors muscles, (ii) craniocervical range of motion, and (iii) the performance on the craniocervical flexion test. Results None of the groups showed any significant immediate, post-training, or retention effects on superficial neck flexors activity and craniocervical range of motion progression. At immediate assessment, mixed focus had greater craniocervical flexion performance than external (MD 0.9, 95%CI 0.2 to 1.5), and internal foci (MD 1.4, 95%CI 0.8 to 2.1). At post-training, mixed focus led to better craniocervical performance compared to external (MD 1.6, 95%CI 0.8 to 2.4) and internal foci (MD 2.7, 95%CI 1.9 to 3.5). External focus had better scores on the craniocervical flexion test performance than internal focus (MD 1.1, 95%CI 0.3 to 1.9). Results remained similar at retention, with mixed focus being superior to internal (MD 2.3, 95%CI 1.7 to 3) and external foci (MD 1.5, 95%CI 0.9 to 2.1) on craniocervical flexion test performance. Similarly, the performance on the craniocervical flexion test performance remained similar at retention between external and internal foci (MD 0.9, 95%CI 0.2 to 1.5). Conclusion In inexperienced asymptomatic participants, different foci of attention were not able to change cervical muscle activity and craniocervical range of motion during the craniocervical flexion test. Mixed focus was better than external and internal focus on the craniocervical flexion test. These findings were retained after one week.
... A literatura sugere que algumas características (de conteúdo e temporais) de feedback extrínseco aceleram a (re)aprendizagem motora, enquanto outras características, inclusive, retardam a (re)aprendizagem. 2 Boa parte dessas informações é baseada na literatura de controle e aprendizagem motora e, portanto, essas informações devem ser interpretadas com cautela. Porém alguns estudos conduzidos com pacientes com disfunções musculoesqueléticas também apresentam informações preliminares que confirmam os resultados de estudos da área de pesquisa de controle e aprendizagem motora. ...
... The ability to maintain an upright sitting posture during prolonged computer work may be difficult if there is no sufficient and accurate intrinsic feedback through proprioceptive sensations. Ribeiro et al. [40] addressed the importance of extrinsic feedback to help execute or improve motor performance in situations where motor improvements are difficult to achieve. Extrinsic feedback is thought to enhance the somatosensory system and restore optimal motor control [41,42]. ...
Article
Full-text available
Prolonged sitting combined with an awkward posture might contribute to the increased risks of developing spinal pain. Maintaining an upright sitting posture is thus often suggested, especially nowadays when people spend longer periods in the sitting posture for occupational or leisure activities. Many types of assistive devices are commercially available to help computer users maintain an upright sitting posture. As the technology advances, wearable sensors that use microelectromechanical technology are designed to provide real-time biofeedback and promote adjusting posture actively. However, whether such wearable biofeedback sensors could assist adjusting sitting posture in computer users during prolonged typing remains unknown. This study aimed to investigate the effects of a wearable biofeedback sensor on maintaining an upright sitting posture. Twenty-one healthy young adults were recruited and performed a 1-h computer typing task twice, with and without using the active biofeedback device. The sagittal spinal posture during computer typing was measured using a three-dimensional motion analysis system. Using the wearable biofeedback sensor significantly decreased the neck flexion (p < 0.001), thoracic kyphotic (p = 0.033), and pelvic plane (p = 0.021) angles compared with not using the sensor. Computer users and sedentary workers may benefit from using wearable biofeedback sensors to actively maintain an upright sitting posture during prolonged deskwork.
Conference Paper
View Video Presentation: https://doi.org/10.2514/6.2022-0509.vid We conducted a human-in-the-loop study of an aircraft flight task to investigate the effectiveness of concurrent bandwidth feedback to improve human performance without increasing cognitive workload when compared to a control group. The Structural Model of the human pilot was investigated to model the results of the aircraft feedback study to better understand how the subjects' performance was changed by exposure to the feedback. We estimated the values of the parameters in the model using a novel parameter identification technique and used the model to estimate the crossover frequency of the combined pilot/vehicle system. The results of this technique were validated using the crossover frequencies identified by an ARX technique, the comparison with which showed good agreement. Linear mixed effect models were used to evaluate how each structural model parameter changed between groups over the course of the experiment. The result of this statistical test led us to propose the extension of the model to include a new term, Kf, which accumulates with exposure to feedback, and which is linearly added to the normal error sensing and gain compensation, Ke. We found evidence that this term accumulates when subjects are exposed to a sufficient amount of feedback over the course of a given trial and that including this term allows for the difference in performance between the control and feedback groups.
Article
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A randomized prospective cohort study of participants with chronic low back pain, seeking physical therapy, with follow-up at weeks 6 and 28. Effects of conventional physiotherapy and physiotherapy with the addition of postural biofeedback were compared. To evaluate the benefits of postural biofeedback in chronic low back pain participants. Biofeedback using electromyographic signals has been used in chronic low back pain with mixed results. Postural feedback had not been previously used. Demographic and psychological baseline data along with range of motion were analyzed from a sample of 47 chronic participants with low back pain randomized into conventional physiotherapy with or without the addition of postural biofeedback. After 6 months, there were 21 dropouts. The participants with biofeedback had markedly improved status in visual analog pain scales, short form-36, and range of motion. The study strongly suggests that postural feedback is a useful adjunct to conventional physiotherapy of chronic low back pain participants.
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66 chronic low back pain sufferers (aged 20–65 yrs) were randomly divided into 3 equal groups. Ss completed a psychological test battery that included the Beck Depression Inventory and the State-Trait Anxiety Inventory; pain monitoring measures, including the McGill Pain Questionnaire (MPQ); and measurement of paraspinal electromyogram (EMG). One group then received paraspinal EMG biofeedback, 1 group received placebo treatment, and the 3rd group received no intervention. All Ss were reassessed immediately after treatment and at 3-mo follow-up. Results show that all groups showed significant reductions in pain, anxiety, depression, and paraspinal EMG following treatment and at follow-up, but there were no differences between groups. A regression analysis failed to identify Ss' characteristics that predicted positive outcome in the biofeedback group. However, high scores on the Evaluative scale of the MPQ and high hypnotizability were significant predictors of positive outcome for the placebo group. It is concluded that paraspinal EMG biofeedback is not a specific treatment for chronic low back pain in a nonhospitalized population. (31 ref)
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This study examined the effectiveness of augmented auditory feedback on the performance and learning of a precision shooting task. Participants included Finnish conscripts (N = 30) who were randomly assigned to one of three groups: auditory feedback group (AFb), knowledge-of-results group (KR), and nontraining control group (Control). Data collection consisted of a pretest, a 4-week acquisition phase, a posttest, and two tests of retention. The effectiveness of the treatment was evaluated in terms of performance outcome, i.e., shooting result. Concurrent auditory feedback related to rifle stability did not facilitate shooting performance in a practice situation. In the posttest and retention tests, the participants in the AFb group displayed more accurate shooting performance than those in the KR and Control groups. Findings suggest that a non-elite shooter's performance can be improved with a 4-week auditory feedback treatment. Given that the learning advantage persisted for delayed retention tests, the observed improvement in skill acquisition was due to relatively permanent variables rather than to temporary effects.
Article
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Relative frequency of knowledge of results (KR) is the proportion of KR presentations to the total number of practice trials. Three experiments are reported in which the effects of variations in acquisition KR relative frequency were examined. Experiment 1 showed that a markedly reduced KR relative frequency during practice was as effective for learning as measured by various retention tests, compared with a 100% KR practice condition. In Experiments 2 and 3, when the scheduling of KR was manipulated so that the number of KR trials was systematically lowered across practice, a reduced average relative frequency enhanced learning as measured by a delayed no-KR retention test (Experiment 2) and a retention test in which KR was provided (Experiment 3). Results are inconsistent with predictions from an acquisition-test specificity hypothesis and conventional motor learning theories and thus suggest a revision in the principles governing the role of KR for motor learning. Empirical support is provided for the KR guidance hypothesis (A. W. Salmoni et al; see record 1984-22348-001) and for various encoding-retrieval operations associated with spaced retrieval practice. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Article
This study examined the effects of variations in relative frequency of knowledge of performance (KP) on acquisition, retention, and transfer of form for a multilimb closed sport skill. Two groups received either 100% relative frequency of KP or 33 % relative frequency of KP while learning the soccer throw-in skill. Participants were boys between the ages of II and 14 years who were unfamiliar with the skill. Participants performed a 30-trial acquisition phase in which KP was provided about one of eight aspects of form. Following acquisition, five trial retention and transfer (to a target at a different distance than experienced in acquisition) tests were administered at 5 min, 24 hi; and 72 he Although no group differences were found for accuracy scores, the 33% group had higher form scores in acquisition and all retention and transfer tests. It was concluded that reducing the relative frequency of KP eliminated a dependency on KP to guide performance in acquisition, which was beneficial for maintaining form in conditions in which KP teas absent.
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Neurorehabilitation is increasingly taking account of scientific findings. Research areas directing stroke rehabilitation are neurophysiology; adaptability to use and activity; biomechanics; skill learning; and exercise science (task, context specificity). Understanding impairments and adaptations enables a reappraisal of interventions-for example, changes in motor control resulting from impairments (decreased descending inputs, reduced motor unit synchronization), secondary soft tissue changes (muscle length and stiffness changes) are adaptations to lesion and disuse. Changes in interventions include increasing emphasis on active exercise and task-specific training, active and passive methods of preserving muscle extensibility. Training has the potential to drive brain reorganization and to optimize functional performance. Research drives the development of training programs, and therapists are relying less on one-to-one, hands-on service delivery, making use of circuit training and group exercise and of technological advances (interactive computerized systems, treadmills) which increase time spent in active practice. Emphasis is on skill training, stressing cognitive engagement and practice, aiming to increase strength, control, skill, endurance, fitness, and social readjustment. Rehabilitation services remain slow to make the changes necessary to upgrade environments, attitudes, and rehabilitation methodologies to those shown to be more scientifically rational and for which there is evidence of effectiveness.
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Examines some critical definitional and experimental-design problems that underlie the principles of knowledge of results (KR) and learning, the KR literature, and how newer principles of KR lead to notions of how KR works in human motor-learning situations. KR is defined as augmented feedback, where the KR is additional to those sources of feedback that are naturally received when a response is made. Transfer tests, usually under no-KR conditions, are essential for unraveling the temporary effects of KR manipulations from their relatively permanent learning effects. When this is considered, the literature reveals findings that produce reasonable agreement, although there are a number of inconsistencies in studies examining the same variables. When learning vs performance effects of KR are separated, a number of contradictions occur; new principles that emerge include the notion that KR acts as guidance, that it is motivating or energizing, and that it has a role in the formation of associations. It is suggested that KR may guide an S to the proper target behavior, with other processes (e.g., simple repetition) being the critical determinants of learning. (4 p ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved).
Article
The application of single motor unit biofeedback training (SMUBT) techniques was compared to traditional therapies in treating chronic low back pain (CLBP). Thirty-six volunteers (who experienced daily pain for 7 years in the T8 to S1 area) were randomly assigned to one of three treatments; SMUBT, relaxation training, or an educational program. The pain level and electromyographic activity of all subjects were assessed by a person blind to the treatment; before, immediately after, and 90 days after treatment. The SMUBT group reported immediately decreased pain which was maintained at 90 days, the relaxation group showed no changes, while the education group reported decreased pain at 90 days. The EMG results showed decreased amplitude and bilateral differences for the SMUBT and education groups. A 4-year follow-up revealed the SMUBT group remained symptom free. Implications and discussion of the results concludes the paper.