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REVIEW Open Access
Neuromuscular training to enhance sensorimotor
and functional deficits in subjects with chronic
ankle instability: A systematic review and best
evidence synthesis
Jeremiah O’Driscoll
1
and Eamonn Delahunt
2,3*
Abstract
Objective: To summarise the available evidence for the efficacy of neuromuscular training in enhancing
sensorimotor and functional deficits in subjects with chronic ankle instability (CAI).
Design: Systematic review with best evidence synthesis.
Data Sources: An electronic search was conducted through December 2009, limited to studies published in the
English language, using the Pubmed, CINAHL, Embase, and SPORTDiscus databases. Reference screening of all
included articles was also undertaken.
Methods: Studies were selected if the design was a RCT, quasi RCT, or a CCT; the patients were adolescents or
adults with confirmed CAI; and one of the treatment options consisted of a neuromuscular training programme.
The primary investigator independently assessed the risk of study bias and extracted relevant data. Due to clinical
heterogeneity, data was analysed using a best-evidence synthesis.
Results: Fourteen studies were included in the review. Meta-analysis with statistical pooling of data was not
possible, as the studies were considered too heterogeneous. Instead a best evidence synthesis was undertaken.
There is limited to moderate evidence to support improvements in dynamic postural stability, and patient
perceived functional stability through neuromuscular training in subjects with CAI. There is limited evidence of
effectiveness for neuromuscular training for improving static postural stability, active and passive joint position
sense (JPS), isometric strength, muscle onset latencies, shank/rearfoot coupling, and a reduction in injury recurrence
rates. There is limited evidence of no effectiveness for improvements in muscle fatigue following neuromuscular
intervention.
Conclusion: There is limited to moderate evidence of effectiveness in favour of neuromuscular training for various
measures of static and dynamic postural stability, active and passive JPS, isometric strength, muscle onset latencies,
shank/rearfoot coupling and injury recurrence rates. Strong evidence of effectiveness was lacking for all outcome
measures. All but one of the studies included in the review were deemed to have a high risk of bias, and most
studies were lacking sufficient power. Therefore, in future we recommend conducting higher quality RCTs using
appropriate outcomes to assess for the effectiveness of neuromuscular training in overcoming sensorimotor deficits
in subjects with CAI.
Keywords: ankle sprain, ankle instability, ankle injury, rehabilitation, injury prevention
* Correspondence: eamonn.delahunt@ucd.ie
2
School of Public Health, Physiotherapy and Population Science, University
College Dublin, Dublin, Ireland
Full list of author information is available at the end of the article
O’Driscoll and Delahunt Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2011, 3:19
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© 2011 O’Driscoll and Delahunt; licensee BioMed Central Ltd. This is an Open Access article distribut ed under the terms of the Creative
Commons Attri bution License (http://creativecommons.org /licenses/by/2.0), which permits unrestricte d use, distribution, and
reproductio n in any medium, provided the original work is properly cited.
Introduction
The ankle joint is the second most common injured
body site in sport with lateral ankle sprains being the
most common type of ankle injury [1]. Thus, ankle
sprains are one of the most frequently encountered
musculoskeletal injuries. Ankle sprains, account for
between 3% and 5% of all Emergency Department atten-
dances in the UK, with about 5,600 incidences per day
[2]. It is probable that many more attend primary care
facilities, such as General Practitioners and sports
clinics, and thus the true incidence may well be under-
estimated. In the acute phase, ankle sprains are asso-
ciated with pain and loss of function, and one quarter of
all injured people are unable to attend school or work
for more than seven days [3].
Unfortunately, the current misconception is that ankle
sprains are simple innocuous injuries. This misconcep-
tion is ill placed and up to 30% of people who incur a
“simple”ankle sprain will report persistent symptoms
such as pain, swelling, decreased function, feelings of
ankle joint instability and recurrent sprains. The generic
term for these persistent symptoms is chronic ankle
instability (CAI).
CAI has recently been defined as an encompassing
term used to classify a subject with both mechanical
and functional instability of the ankle joint [4]. Further-
more according to the definition put forth by Delahunt
et al [4], to be classified as having CAI, residual symp-
toms such as episodes of ankle joint ‘’giving way’’ and
feelings of ankle joint instability should be present for a
minimum of 1 year post-initial sprain. Mechanical
instability (MI) of the ankle joint is characterized by
excessive inversion laxity of the rear foot or excessive
anterior laxity of the talocrural joint. As a result, joint
range of motion is beyond the normal expected physio-
logical or accessory range of motion for that joint [4].
Functional instability (FI) of the ankle joint refers to a
situation whereby a subject reports experiencing fre-
quent episodes of ankle joint ‘’giving way’’ and feelings
of ankle joint instability [4].
The well accepted paradigm put forth by Hertel [5]
suggests that the development of CAI is dependent
upon the interaction of various mechanical and sensori-
motor insufficiencies. Mechanical insufficiencies include
excessive joint laxity, restricted accessory joint gliding
and micro-subluxations. Sensorimotor insufficiencies
include alterations in muscle activation patterns,
impaired postural stability, and altered movement pat-
terns during gait and other functional activities.
The high rate of ankle sprains sustained during activ-
ities of daily living, occupational endeavour and across
all sports, as well as the severity and subsequent nega-
tive consequences associated with the development of
CAI motivates attention for preventive measures against
this type of injury. Exercises to improve neuromuscular
control in subjects with CAI are advocated throughout
the literature [6-10], yet there remains little unequivocal
evidence regarding their effectiveness. Therefore, the
primary aim of this systematic review was to assess the
efficacy of neuromuscular training in enhancing sensori-
motor function in subjects with CAI.
Methodology
Literature Search
The literature search was conducted in two stages. For
stage one, an initial electronic search was performed
and studies were evaluated for inclusion. Stage two con-
sisted of a hand search of the reference lists of the arti-
cles selected in stage one. The electronic search using
pre-defined search terms was restricted to English-lan-
guage publications found in the following databases
through December 2009: PubMed (National Library of
Medicine, Bethesda, MD), Embase, CINAHL, and
SPORTDiscus. The latter two databases were searched
simultaneously using EBSCOhost (EBSCO Industries,
Inc, Birmingham, AL). The reference lists of all included
articles were then checked for additional pertinent stu-
dies. The primary investigator (PI) conducted the search
(see additional file 1)
Article Inclusion and Exclusion Criteria
Once the search had been completed, titles and
abstracts of the retrieved articles were reviewed by the
PI. For final inclusion the articles had to fulfil all of the
following criteria:
1) study design had to be either a randomized con-
trolled trial (RCT), a quasi RCT, or a clinical con-
trolled trial (CCT).
2) one of the treatment options had to consist of a
neuromuscular training programme (e.g. postural
stability training, strength training, etc).
3) each study had to use an inclusion criterion of
giving way or frequent sprains, or to have described
the target condition as functional ankle instability
(FAI), FI or CAI.
Studies using mixed group design (i.e. groups contain-
ing subjects with CAI/FI and healthy controls) were
excluded from the review. Studies which assessed the
additional effect of adjunctive therapies to neuromuscu-
lar training such as taping and stochastic resonance
[6,10] were included. However for such studies (i.e. stu-
dies examining the additional effect of adjunctive thera-
pies), results and effect sizes were acquired for the
neuromuscular training groups only. The additional
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effects of adjunctive interventions were deemed to be
beyond the scope of this study.
Risk of Bias Assessment
Risk of bias in the included studies was assessed by the
PI, using the Cochrane collaboration’s tool for assessing
such risk [11]. This tool was adapted for the objective of
this review and consists of 5 domains, with 11 items in
total (see additional file 2). Each item was rated as ‘yes’,
‘no’,or‘unsure’. Studies with 6 or more points on the
risk of bias assessment were regarded as having a low
risk of bias. This risk of bias tool has previously been
utilised by van Rijn et al [12] to investigate the effective-
ness of additional supervised exercises compared to con-
ventional treatment alone in patients with acute ankle
sprains.
Data Extraction
The PI extracted relevant data from the included stu-
dies. The study characteristics extracted included infor-
mation on the target population (gender, history of the
condition, sample size etc.), presence of concomitant
MI, training protocols implemented, outcome measures
and significant findings. In cases of uncertainty about
the extracted data from the included studies a second
reviewer was consulted.
Where feasible the core findings of each article were
expressed as effect sizes (ES). If possible, these measures
were extracted directly from the article. For articles in
which this information was not presented, as was gener-
ally the case, effect sizes were calculated using mean
values and a pooled standard deviation in accordance
with the methods described by Cohen [13]. Effect sizes
between 0.2 and 0.49 can be interpreted as weak, 0.5 to
0.79 as medium, and greater than 0.8 as strong [13].
Furthermore, 95% confidence intervals were also
calculated.
Outcome measures were grouped into the following
categories:
■Static postural stability
■Dynamic postural stability
■Joint position sense
■Strength measures
■Muscle onset latencies
■Joint kinematic data
■Muscle fatigue values
■Patient perceived stability
Data Analysis
The main comparisons of this review were time (i.e. pre
and post intervention within the CAI group), and group
(i.e. between CAI group and control group) training
effects of various neuromuscular training programmes
on commonly used sensorimotor outcomes to assess for
treatment efficacy in subjects with CAI. Due to the clin-
ical heterogeneity of the trials concerning population,
intervention and outcome measures, statistical pooling
was not possible. Therefore the data was analysed using
a best evidence synthesis as advocated by van Tulder et
al [14]. This rating system consists of 4 levels of scienti-
fic evidence based on the quality of the included studies:
1) Strong evidence; provided by generally consistent
findings in multiple RCTs assessed as having low
risk of bias.
2) Moderate evidence; provided by generally consis-
tent findings in one RCT assessed as having low risk
of bias, and one or more RCTs assessed as having
high risk of bias, or by generally consistent findings
in multiple RCTs assessed as having high risk of
bias.
3) Limited or conflicting evidence; only one RCT
(assessed as having either a low or high risk of bias),
or inconsistent findings in multiple RCTs.
4) No available evidence; no published RCTs that
have assessed for interventional effect.
Results
Literature Search
Our electronic search resulted in 5142 potentially rele-
vant articles. After reviewing titles and abstracts 24
potentially relevant articles remained. Of these, 12 arti-
cles met our inclusion criteria after reviewing the full
text. A further 2 relevant articles were retrieved after
checking the reference lists of included studies. Hence a
total of 14 articles were included in this review. The
search strategy and results are presented in Figure 1.
Assessment of Bias
Figure 2 presents the overall assessment of the risk of
bias. The assessment of the risk of bias for the indivi-
dual studies is presented in Table 1. Thirteen of the stu-
dies were assessed as having high risk of bias, whilst
only one was deemed to be of low risk. The most preva-
lent shortcomings were found in the items relating to
blinding (patient, care provider, outcome assessor), allo-
cation concealment, randomisation, and the acceptability
of compliance rates.
Description of Included Studies
Tables 2, 3, 4, 5, 6, 7, 8 and 9 present the characteristics
of the included studies. Neuromuscular training in the
included studies consisted of a wide variety of proprio-
ceptive and strength training drills. Some studies also
implemented protocols combining both interventions.
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Embase
PubMed
SPORTDiscus
Articles retrieved for more
detailed evaluation
(n=703)
Potentially relevant articles identified and screened for retrieval
(n=5142)
SEARCH
CINAHL
Articles excluded based on title
(n=4439)
Potentially relevant articles identified
and screened for retrieval
(n=24)
Articles excluded based on
abstract
(n=679)
Articles excluded for failing to meet
inclusion criteria
(n=12)
Articles retrieved from the
reference lists of included articles
(n=2)
Articles included in the systematic review
(n=14)
Figure 1 Flow chart for manuscript review process.
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The included studies were considered too heterogeneous
to perform a meta-analysis. Therefore, we refrained
from pooling and performed a best evidence synthesis.
Furthermore, the contrasting nature of the various types
of proprioceptive and strength training made it impossi-
ble to execute an analysis grouped by type of interven-
tion. For that reason, we described the results of the
main comparisons per outcome measure. Tables 10, 11,
12 and 13 present the results of the studies per outcome
measure.
Effectiveness of Neuromuscular Training
Static Postural Stability
Static postural stability impairments have frequently
been associated with CAI [15-17], and have predicted
anklespraininjuryinphysicallyactiveindividuals
[18,19]. Hence, the assessment of static postural stability
in single leg stance (SLS) is one method of determining,
the efferent, or muscular response to afferent
stimulation.
Nine studies described static postural stability as an
outcome measure, all of which had a high risk of bias
[6-8,10,20-24]. Static postural stability was measured
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Timing of outcome assessment similar?
Compliance acceptable?
Co-interventions avoided?
Groups similar at baseline?
Intention to treat analysis?
Drop-out rate described?
Outcome assessor blinded?
Care provider blinded?
Patient blinded?
Allocation concealed?
Adequate randomisation?
Yes
No
Unsure
Figure 2 Results of risk of bias assessment: [frequency (%) of scores per item (yes, no, unsure)].
Table 1 Results of the risk of bias (+ = yes; - = no; ? =
unsure)
1234567891011
1.Bernier & Perrin, 1998 [20] ? ? -? ?+?+? ? +
2.Docherty et al, 1998 [29] ? ? - ? ? - ? + + ? ?
3.Rozzi et al, 1999 [21] - - - ? ? ? ? + ? ? ?
4.Matsusaka et al, 2001 [6] ? ? - - ? ? ? + ? ? +
5.Eils & Rosenbaum, 2001
[22]
??-????+? ? +
6.Kaminski et al, 2003 [32] ? ? - ? ? - ? + ? ? ?
7.Powers et al, 2004 [23] ??--+-??? ? +
8.Clark & Burden, 2005 [31] ? ? - - ? - ? + ? ? +
9.Kynsburg et al, 2006 [30] - ? - ? ? - ? + ? ? +
10.Ross et al, 2007 [10] ? ? - ? ? - ? + ? ? ?
11.Hale et al, 2007 [7] ?? - - ?+?+? ? +
12.McKeon et al, 2008 [8] + + - ? ? - ? + ? ? +
13.McKeon et al, 2009 [35] + + - - - + + + + ? +
14.Han et al, 2009 [24] ? ? - - ? + + + ? ? +
1 = Adequate randomisation?; 2 = Allocation concealed?; 3 = Patient blinded?;
4 = Care provider blinded?; 5 = Outcome assessor blinded?; 6 = Drop-out rate
described?; 7 = Intention to treat analysis?; 8 = Groups similar at baseline?;
9 = Co-interventions avoided?; 10 = Compliance acceptable?; 11 = Timing of
outcome assessment similar?
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Table 2 Characteristics of the included studies
Author Study
Population
Presence
of MI
Groupings/Intervention Outcome Measures Significant Findings Within Group Effect
Sizes
Between Group Effect
Sizes
Bernier &
Perrin,
1998 [20]
48 males &
females with
FAI
Not
specified
Control group (n = 14) - no
intervention
Sham electrical stimulation
group (n = 14)
Training group (n = 17) -
static & dynamic balance
training 3 times a week × 6
weeks
SI & MES in SLS for 4 conditions:
stable platform with eyes open
and eyes closed, and dynamic
platform with eyes open and
eyes closed
Active and passive JPS data for 7
positions:
15° inversion, 0° degrees neutral,
and 10° of eversion, performed at
0° and 25° of plantarflexion.
Maximum inversion in 25°
plantarflexion was also assessed
Training group showed significant MES
improvements over the other 2 groups
in AP & ML directions for the stable
platform and dynamic platform
conditions respectively with eyes closed
Significant within training group
improvements were also noted in the A/
P and M/L directions for both conditions
with eyes closed
MES - stable platform,
eyes closed:
A/P direction: 1.08;
95% CI (10.52-30.48)
M/L direction: 1.09;
95% CI (5.28-25.72)
MES - dynamic
platform, eyes closed:
A/P direction: 0.71;
95% CI (68.27-78.73)
M/L direction: 0.958;
95% CI (65.25-74.75)
MES - stable platform,
eyes closed:
A/P direction: 0.99
95% CI (12.13-31.87)
M/L direction: 0.92; 95%
CI (12.63-33.37)
MES - dynamic platform,
eyes closed:
A/P direction: 0.52; 95%
CI
(63.9-81.10)
M/L direction: 0.55; 95%
CI
(60.9-78.1)
Docherty
et al,
1998 [29]
20 healthy
college
students (10
males, 10
females)
with FAI
Not
specified
Training group (n = 10) -T-
band strengthening 3 times
a week × 6 weeks
Control group (n = 10) - no
intervention
Dorsiflexor and evertor isometric
muscle strengths
Active JPS data collected at 20°
for inversion & plantarflexion, &
at 10° for eversion and
dorsiflexion
Significant beween group interactions
for dorisflexion and eversion strength,
and inversion, and plantarflexion JPS
Significant improvements in all strength
and JPS measures post-test within the
training group
Dorsiflexion strength:
2.99; 95% CI (38.51-
45.39)
Eversion strength:
0.83; 95% CI (34.42-
41.48)
Inversion JPS: 0.98;
95% CI (2.38-7.22)
Eversion JPS: 0.77;
95% CI (1.55-5.15)
Dorsiflexion JPS: 0.85;
95% CI (1.56-4.54)
Plantarflexion JPS: 1.51;
95% CI (2.51-6.79)
Dorsiflexion strength:
2.93;
95% CI (39.31-45.19)
Eversion strength: 1.94;
95% CI (27.77-44.93)
Inversion JPS: 1.32; 95%
CI (2.92-6.28)
Plantarflexion JPS: 1.56;
95% CI (2.06-4.84)
MI = mechanical instability; FAI = functional ankle instability, SI = stability index, MES = modified equilibriu m score, JPS = joint position sense, A/P = anterior-posterior, M/L = medial/lateral
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Table 3 Characteristics of the included studies (continued)
Author Study Population Presence
of MI
Groupings/Intervention Outcome Measures Significant Findings Within Group Effect
Sizes
Between Group Effect
Sizes
Rozzi et al,
1999 [21]
26 active university
students (15 male, 11
female) with and without
FAI
Not specified Training group (n = 13) -
unilateral static and
dynamic Biodex stability
training 3 times a week ×
4 weeks
Healthy control group
(n = 13) - identical training
to the FAI group
Biodex generated SIs,
recorded for 4 conditions:
involved limb at levels 2
and 6, and uninvolved
limb at levels 2 and 6
AJFAT scores.
Subjects in both groups
demonstrated significant post-
training improvements in
balance ability at stability
levels 2 and 6
Post-training AJFAT scores
were significantly better for
both groups
SI at level 2: 1.13;
95% CI (2.25-6.31)
SI at level 6: 0.73;
95% CI (1.09-2.47)
AJFAT Scores: 2.39;
95% CI (19.47-23.41)
No significant between
group effect for SI at
level 2 or 6 & AJFAT
Matsusaka
et al, 2001
[6]
22 university students (10
women, 12 men) with
unilateral FAI
Present in 73%
of subjects, as
evidenced by a
+ve anterior
drawer sign
Tape and exercise group
(n = 11, 7 with MI) - ankle
disc training 5 times per
week × 10 weeks with
ankle tape in situ
Exercise only group
(n = 11, 9 with MI) -
identical programme
without ankle tape in situ
Healthy adult group
(n = 21) -tested once to
determine normal range of
rectangular area values
Postural sway was
quantified using
rectangular area values
taken pretest and at
2,3,4,5,6,8, and 10 weeks of
training
In the exercise only group
postural sway values improved
significantly after 6 weeks and
were within the normal range
after 8 weeks
Exercise only group:
Rectangular area
values at 6 weeks:
1.501
12.2-15.5
Rectangular area
values at 8 weeks:
1.921
11.6-14
No significant between
group effect at 6 & 8
weeks
MI = mechanical instability; FAI = functional ankle instability, +ve = positive; SI = stability index, AJFAT = ankle joint function al assessment tool
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Table 4 Characteristics of the included studies (continued)
Author Study Population Presence
of MI
Groupings/
Intervention
Outcome Measures Significant Findings Within Group Effect
Sizes
Between Group
Effect Sizes
Eils &
Rosenbaum,
2001 [22]
30 subjects (18 male,
12 female) with 48
unstable ankles
Not specified Training group (n =
20, 31 unstable ankles)
- multi-station
proprioceptive
exercises once per
week × 6 weeks
Control group (n = 10,
17 unstable ankles) -
no intervention
Passive JPS was assessed
for 10° and 20° of
dorsiflexion, and 15° and
30° of plantarflexion
Postural Sway in M/L and
A/P directions as well as
sway distance was assessed
in SLS
MRTs of TA, PL, and PB
following a sudden
inversion perturbation
Frequency of recurrence at
one year follow up
In the exercise group the results
showed significant improvements in
JPS (except for 10° of DF), postural
sway measures, as well as a
significant increase in MRTs for PL
and PB
A significant reduction in frequency
of ankle sprains at one year follow
up was also noted within the
exercise group
JPS at 20° DF: 0.71;
95% CI (1.22-1.68)
JPS at 15° PF: 0.90;
95% CI (1.6-2.2)
JPS at 30° PF: 0.86;
95% CI (1.87-2.43)
Mean Error: 0.98; 95%
CI (1.57-1.93)
Postural Sway, std dev
M/L: 0.26; 95% CI
(4.14-4.66)
Postural Sway, max
sway M/L: 0.48; 95%
CI (20.01-22.69)
Postural Sway, total
sway distance: 0.41;
95% CI (423.66-498.64)
MRT of PL: 0.50; 95%
CI (60.96-65.44)
MRT of PB: 0.54; 95%
CI (66.4-70.9)
No significant
between group
difference was
observed
Kaminski et
al, 2003 [32]
38 (22 men, 16
women) subjects
with FAI
Not specified Strength training
group - T-band
strengthening of
invertors & evertors 3
times per week × 6
weeks
Proprioception training
group - “T-band kicks”
3 times per week × 6
weeks
Coupled strength &
proprioception group -
both exercise
protocols combined
Control group no
intervention
Isokinetic strength
measures of average torque
and peak torque eversion
to inversion (E/I) ratios,
calculated at 30°/sec and
120°/sec
No significant differences in average
torque or peak torque E/I ratios for
any of the groups
No significant within
group effect was
observed
No significant
between group
difference was
observed
MI = mechanical instability; FAI = functional ankle instability; JPS = joint position sense; A/P = anterior-posterior; M/L = medial/lateral; SLS = single leg stance; MRT = muscle reaction time; TA = tibialis anterior; PL =
peroneus longus; PB = peroneus brevis
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Table 5 Characteristics of the included studies (continued)
Author Study
Population
Presence
of MI
Groupings/
Intervention
Outcome Measures Significant Findings Within Group
Effect Sizes
Between
Group Effect
Sizes
Powers
et al,
2004
[23]
38 subjects
(22 males,
16 females)
with
unilateral
FAI
Absent on
examination
Strength training
group - theraband
strength training 3
times a week × 6
weeks
Proprioceptive
training group
-proprioceptive
training involving “T-
band kicks”3 times
a week × 6 weeks
Combination
training group
-performed a
combination of both
training protocols 3
times a week × 6
weeks
Control group - no
intervention
Muscle fatigue was
determined using
the median power
frequency (fmed)
from an EMG signal
for TA and PL
COP values for A/P
and M/L directions,
and the mean
overall deviations
from COP were
obtained
No significant effects of
any intervention on
measures of muscle fatigue
and static balance
No significant
within group
effect was
observed
No significant
effect between
group effect
was observed
Clarke
and
Burden,
2005
[31]
19 male
subjects
with FAI
Absent on
examination
Control group (n =
9) - no intervention
Exercise group (n =
10) - wobble board
training 3 times a
week × 4 weeks
MRTs were measured
for TA, and PL in
response to sudden
inversion
AJFAT scores
The exercise group showed
a significant decrease in
muscle onset latency for
both TA and PL, and a
significant improvement in
AJFAT scores
TA = 1.29
PL = 1.20
Both effect sizes
were reported in
the paper
without
presentation of
mean ± SD
values
Data was
presented in
graphical
format without
the reporting of
mean ± SD
values
MI = mechanical instability; FAI = functional ankle instability; EMG = electromyography, TA = tibialis anterior; PL = peroneus longus; COP = center of pressure; A/
P = anterior-posterior; M/L = medial/lateral; MRT = muscle reaction time; AJFAT = ankle joint functional assessment tool; SD = standard deviation
Table 6 Characteristics of the included studies (continued)
Author Study
Population
Presence
of MI
Groupings/
Intervention
Outcome Measures Significant Findings Within
Group
Effect
Sizes
Between
Group
Effect
Sizes
Kynsburg
et al,
2006 [30]
20 subjects
(10 males,
10
females):10
with
unilateral
FAI, 10
healthy
matched
controls
Not specified FAI training group
(n = 10) -single leg
proprioceptive
training 3 times
per week × 6
weeks
Healthy control
group (n = 10) -
no intervention
Active JPS was measured
using the slope-box test
for 11 different slope
amplitudes in 4
directions (anterior,
posterior, lateral, and
medial).
Within the training group
there was a significant
improvement in JPS error
in the posterior direction,
as well as an overall
improvement of the mean
absolute estimate error
Posterior
JPS: 0.47;
95% CI
(1.76-5.0)
Cumulative
JPS: 0.40;
95% CI
(1.99-5.43)
Insufficient
data
Control
group
mean ± SD
values are
not
reported in
the paper
Ross et al,
2007 [10]
30 subjects
(16 females,
14 males)
with FAI
Majority of
subjects had MI
(67% with a
positive anterior
drawer, 76%
with talar tilt
laxity)
Coordination
training group (n =
10) - single leg
coordination
training 3 times a
week × 6 weeks
SR coordination
training group (n =
10) - identical
exercises but
received SR
stimulation during
training
Control group (n =
10) - no
intervention
COP measures: A/P sway
velocity, M/L sway
velocity, M/L standard
deviation, M/L maximum
excursion, and area
The control and
coordination group
posttest outcomes were
not significantly different
for any of the measures
recorded
No
significant
within
group
effect was
observed
No
significant
effect
between
group
effect was
observed
MI = mechanical instability; FAI = functional ankle instability; JPS = joint position sense; COP = center of pressure; A/P = anterior-posterior; M/L = medial/lateral
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using a multitude of different measures thereby making
comparisons between studies extremely difficult. Bernier
and Perrin [20] looked at the effect of 6 weeks of static
and dynamic postural stability training on sway index
(SI) measures, and modified equilibrium scores (MES).
Measures were taken for weight-bearing SLS under both
static and dynamic conditions, with and without visual
cues. Outcomes were obtained for both the anteropos-
terior (AP) and mediolateral (ML) directions. Based on
this one high risk RCT there is limited evidence for
both time and group effect for a number of static and
dynamic MES scores post training, namely the stable
platform AP, and dynamic platform ML conditions. For
two other MES conditions, namely the stable platform
ML, and dynamic platform AP conditions, there was
limited evidence of time but not group effect following
the intervention. This effect was only apparent whilst
subjects were tested under the eyes closed condition. No
such effect was evident under the eyes open test condi-
tion. Based on the same high risk RCT there is limited
evidence of neither time nor group effect for neuromus-
cular training for any of the 8 different SI measurements
(i.e. stable and dynamic platform conditions in the AP
and ML directions, with and without visual cues), or the
4 other MES conditions (i.e. stable and dynamic plat-
form conditions in the AP and ML directions, with eyes
open).
Based on another high risk study [21], which investi-
gated the effect of 6 weeks of theraband strengthening
in various planes of talocrural and subtalar joint motion,
there is limited evidence of both time and group effect
for two Biodex Stability System generated stability
indices obtained in SLS.
McKeon et al [8] assessed the effect of 4 weeks of pos-
tural stability training drills that emphasised dynamic
stabilisation in SLS on a variety of centre of pressure
(COP) excursion, and time-to- boundary (TTB) mea-
sures obtained in SLS. The COP measures included a
95% confidence ellipse, velocity, range, and standard
deviation (SD), and were ascertained for both the AP
and ML directions with and without visual cues. The
TTB measures included the absolute minimum TTB,
mean of TTB minima, and SD of TTB minima, in both
AP and ML directions with eyes open and eyes closed.
Based on this single high risk RCT there is limited evi-
dence for time and group improvements for COP velo-
city values in a ML direction under the eyes closed
condition post training. There is also limited evidence of
both time and group effects for a number of TTB mea-
sures including the absolute minimum TTBML, mean
minimum TTBML, mean minimum TTBAP, and SD
minimum TTBAP, all of which occurred under the eyes
closed test condition. There was limited evidence of
neither group nor time effect following neuromuscular
training for any of the other COP or TTB measures
evaluated. Based on another high risk RCT [22], which
looked at the effect of 6 weeks of multi-station proprio-
ceptive exercises on COP excursions, there is limited
evidence to support a time effect for COP total mea-
sures with eyes open following training.
Based on three high risk RCTs [6,8,10], there is con-
flicting evidence regarding improvements in time and
group effect for COP area values assessed in SLS, with
eyes closed following neuromuscular training. Matsusaka
et al [6], and Ross et al [10] looked at the efficacy of sin-
gle leg coordination training over 10 and 6 weeks
Table 7 Characteristics of the included studies (continued)
Author Study
Population
Presence
of MI
Groupings/Intervention Outcome
Measures
Significant Findings Within Group
Effect Sizes
Between
Group Effect
Sizes
Hale
et al,
2007
[7]
48 subjects
(28 females,
20 males),
29 with CAI
and 19
healthy
controls
Not
specified
FAI training group (n =
16) - 4 weeks of training
which addressed ROM,
strength, neuromuscular
control, and functional
tasks. Subjects visited the
lab on 6 occasions over
the 4 weeks, and
exercised 5 times per
week at home
FAI control group
(n = 13) - no intervention
Healthy control group
(n = 19) - no intervention
COP velocity in SLS
with eyes open
and closed
SEBT measures
taken in all 8
directions
FADI and FADI-
Sport scores
Following rehabilitation,
the FAI group had
significantly greater SEBT
reach improvements on
the involved limb than
the other two groups in
the posteromedial,
posterolateral, and lateral
directions as well as the
mean of all 8 reach
directions. Similarly, the
CAI-rehab group showed
showed significant
improvements over the
CAI-control group, and
the healthy group, for
FADI and FADI-Sport
scores
Pre to post-test
scores are presented
in the paper for the
CAI group as
follows (values are
presented as %
change):
P/M: 0.07; 95%
CI (0.02-0.12)
L: 0.09; 95%
CI (0.04-0.08)
P/L: 0.12; 95%
CI (0.06-0.18)
FADI: 7.30; 95%
CI (2.47-12.13)
FADI Sport: 11.10;
95% CI (6.35-15.86)
Insufficient
data was
presented for
the
calculation of
between
group effect
sizes
MI = mechanical instability; CAI = chronic ankle instability; ROM = range of movement; COP = center of pressure; SEBT = Star Excursion Balance Test; FADI = foot
and ankle disability index; P/M = posterior-medial; L = lateral; P/L = posterior-lateral
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respectively, whilst McKeon et al [8] assesed the efficacy
of 4 weeks of balance training that emphasised dynamic
stabilisation in SLS. Based solely on the study by Ross et
al [10], there is limited evidence of no effectiveness fol-
lowing training for time or group improvements in ML
COP Max measures with eyes open. Based on two high
risk RCTs [22,23], there is moderate evidence of no
effectiveness for strength or proprioceptive training on
COP ML and AP measures when assessed with eyes
open. Based on two other high risk RCTs [8,10] there is
moderate evidence of no effect for both time and group
conditions for ML COP velocity, or ML COP SD values
when assessed with eyes open. Furthermore based on
these two studies there is moderate evidence of no
group effect for AP COP velocity measures, and con-
flicting evidence regarding time effect after training,
when assessed with eyes open.
Based on one other high risk RCT [24] there is limited
evidence of no effect for both time and group conditions
for total distance travelled when assessed with eyes
open.
Dynamic Postural Stability
Two high risk studies [7,8] described dynamic postural
stability as an outcome measure. Both studies utilised
the Star Excurion Balance Test (SEBT). Deficits in
dynamic balance, as measured by the SEBT, have consis-
tently been demonstrated in those with CAI [25-27].
Hale et al [7] looked at between group differences for
all 8 directions of the SEBT, whereas McKeon et al [8]
analysed time and group effects in the anterior, postero-
medial and posterolateral directions only. Based on
these two studies there is moderate evidence of group
effect for improvements in reach distance in the poster-
omedial and posterolateral directions of the SEBT fol-
lowing neuromuscular training. There is moderate
evidence of no group effect in the anterior direction.
Based solely on the study by McKeon et al [8], there is
limited evidence of time effect in the posteromedial and
posterolateral directions. Based on the study by Hale et
al [7], there is limited evidence of group effect in the lat-
eral direction, and for the mean of all 8 directions of the
SEBT. There is limited evidence of no effectiveness, or
no available evidence to support time or group effects
for all other components of the SEBT.
Joint Position Sense
Another proprioceptive measure commonly used to assess
for improvements post training in subjects with CAI is
joint position sense (JPS). Mechanoreceptors are sensitive
to pressure and tension caused by dynamic movement
and static positions. Hence if mechanoreceptor function is
Table 8 Characteristics of the included studies (continued)
Author Study
Population
Presence
of MI
Groupings/
Intervention
Outcome Measures Significant Findings Within Group Effect
Sizes
Between Group
Effect Sizes
McKeon
et al,
2008 [8]
31
physically
active
individuals
(12 males,
19 females)
with a
history of
FAI
Not
specified
CAI balance
training group
(n = 16) -
balance
training that
emphasised
dynamic
stabilisation in
SLS 3 times per
week × 4
weeks
CAI control
group (n = 15)
-no
intervention
FADI and FADI-Sport
scores
COP excursion
measures including a
95% confidence
ellipse, velocity, range
and SD
TTB measures
including the absolute
minimum TTB, mean
of TTB minima, and
SD of TTB minima in
the A/P and M/L
directions with eyes
open and closed
SEBT measures in the
A/P, P/M, and P/L
directions
The balance training
group had significant
improvements in the
FADI and the FADI-
Sport scores, in the
magnitude and
variability of TTB
measures with eyes
closed, and in reach
distances in the
posteromedial and
posterolateral
directions of the SEBT.
Only one of the
summary COP-based
measures (velocity of
COPML, eyes closed)
significantly changed
after balance training
FADI Scores: 0.98;
95% CI (86.35-92.85)
FADI-Sport Scores:
1.25; 95% CI
(72.0-82.9)
Absolute Min TTB M/
L eyes closed: 0.8;
95% CI (0.48-0.56)
Mean Min TTB M/L
eyes closed: 0.6; 95%
CI (1.77-2.23)
Mean min TTB A/P
eyes closed: 0.41;
95% CI (4.93-6.43)
SD Min TTB A/P eyes
closed: 0.75; 95%
CI (3.05-3.97)
Velocity of COP A/P
eyes open: 0.07; 95%
CI (0.64-0.84)
Velocity of COP M/L
eyes closed: 0.52;
95% CI (1.85-2.27)
SEBT P/M reach: 0.64;
95% CI (0.81-0.93)
SEBT P/L reach: 0.67;
95% CI (0.76-0.88)
FADI Scores: 0.68;
95% CI
(82.13-92.97)
FADI-Sport Scores:
1.63; 95% CI
(70.09-81.21)
Absolute Min TTB M/L
eyes closed: 0.60; 95%
CI (0.49-0.57)
Mean Min TTB M/L
eyes closed: 0.54; 95%
CI (1.79-2.25)
MeanMinTTB A/P
eyes closed: 0.32; 95%
CI (4.76-6.09)
SD Min TTB A/P eyes
closed: 1.18; 95%
CI (3.02-3.86)
Velocity of COP A/P
eyes open: 0.38; 95%
CI (0.66-0.8)
Velocity of COP M/L
eyes closed: 0.42; 95%
CI (1.81-2.23)
SEBT P/M reach: 1.83;
95% CI (0.82-0.9)
SEBT P/L reach: 1.0;
95% CI (0.77-0.88)
MI = mechanical instability; CAI = chronic ankle instability; FADI = foot and ankle disability index; COP = center of pressure; TTB = time-to-boundary;
SD = standard deviation; SEBT = Star Excursion Balance Test; A/P = anterior-posterior; M/L = medial/lateral; P/M = posterior-medial; P/L = posterior-lateral;
Min = minimum
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disrupted as is the case in subjects with CAI this often pre-
sents as reduced acuity in sensing joint position thereby
leading to increased joint position errors. Konradsen and
Magnusson [28] reported that an inversion error greater
than 7 degrees would equal a 5 mm drop of the lateral
border of the foot, which would lead to a hyper-invered
foot position at initial contact therefore increasing the
potential for injury.
In total 4 high risk studies looked at JPS. Bernier and
Perrin [20], and Docherty et al [29] looked at active JPS
in non weight-bearing (NWB) following 6 weeks of bal-
ance training, and strength training respectively. Kyns-
burg et al [30] looked at active JPS in WB using the
slope box method of analysis pre and post 6 weeks of
proprioceptive training. NWB passive JPS was also ana-
lysed in 2 studies [20,21] following 6 weeks of proprio-
ceptive training. Based on one high risk RCT [29] there
is limited evidence of both time and group effects for
significant improvements in joint acuity for 20 degrees
inversion, 10 degrees dorsiflexion, and 20 degrees
plantarflexion following neuromuscular training. Based
on two studies [20,29] there is conflicting evidence
regarding time effect, and moderate evidence of no
group effect for improvement in JPS for 10 degrees of
eversion. Based on the study by Bernier and Perrin [20]
there is limited evidence of neither time nor group
effect for active or passive angle reproduction at 15
degrees inversion, 0 degrees of neutral, 10 degrees of
eversion, the aforementioned angles repeated at 25
degrees of plantarflexion, or maximal inversion which
was defined as minus 5 degrees from each individual’s
maximum inversion active range. There is limited evi-
dence of time effect in the posterior and combined
directions of active WB JPS based on the high risk study
by Kynsburg et al [30]. Based on the same study there is
limited evidence of no time effect in the anterior, medial
and lateral directions. Group effects were not analysed
in this study. Based on another high risk study [22]
there is limited evidence of time effect improvements in
angle reproduction for 10 and 20 degrees of
Table 9 Characteristics of the included studies (continued)
Author Study Population Presence
of MI
Groupings/
Intervention
Outcome
Measures
Significant
Findings
Within Group
Effect Sizes
Between Group
Effect Sizes
McKeon
et al,
2009
[35]
31 physically active
individuals (12
males, 19 females)
Not
specified
CAI balance
group (n = 17)
- training
designed to
challenge
recovery of
single limb
balance 3 times
per week × 4
weeks
CAI control
group (n = 15)
-no
intervention
Kinematic
measures of
rearfoot inversion/
eversion, shank
rotation, and the
coupling
relationship of
these two
segments
throughout the
gait cycle were
taken whilst
walking and
running
A significant
decrease was
noted in the
shank/rearfoot
coupling variabilty
during walking as
measured by the
deviation phase
within the balance
training group, and
between the
balance training
group and the
control group at
post-test
Shank/rearfoot
coupling: 0.62; 95%
CI (11.71-17.59)
Shank/rearfoot
coupling: 0.59; 95%
CI (11.42-17.89)
Han
et al,
2009
[24]
40 subjects (20
males, 20 females)
Not
specified
CAI exercise
group (n = 10)
- resisted “T-
band kicks”3
times per week
× 4 weeks
CAI control
group (n = 10)
-no
intervention
Healthy normals
exercise group
(n = 10) -
exercise
programme as
per CAI exercise
group
Healthy normals
control group
(n = 10) - no
intervention
TDT of the COP in
SLS at 4 and 8
weeks
Balance training
significantly
improved in
subjects with and
without a history
of FAI.
Furthermore, the
exercise
programme caused
a significant
improvement in
balance for the FAI
exercise group
when compared to
the FAI control
group and the
healthy normal
group
Insufficient data
No mean ± SD data
presented for
calculation
Insufficient data
No mean ± SD data
presented for
calculation
MI = mechanical instability; CAI = chronic ankle instability; TDT = total distance travelled; COP = center of pressure; SLS = single leg stance; SD = standard
deviation
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Table 10 Results of studies per outcome
OUTCOME DESCRIPTION STUDIES TIME
EFFECT
GROUP
EFFECT
BEST EVIDENCE
SYNTHESIS (TIME)
BEST EVIDENCE
SYNTHESIS (GROUP)
Static Postural
Stability
S.I. for 8 conditions
Stable platform (E.O) AP 1 HR RCT NO NO LENE LENE
Stable platform (E.O) ML 1 HR RCT NO NO LENE LENE
Stable platform (E.C) AP 1 HR RCT NO NO LENE LENE
Stable platform (E.C) ML 1 HR RCT NO NO LENE LENE
Dynamic platform (E.O) AP 1 HR RCT NO NO LENE LENE
Dynamic platform (E.O) ML 1 HR RCT NO NO LENE LENE
Dynamic platform (E.C) AP 1 HR RCT NO NO LENE LENE
Dynamic platform (E.C) ML 1 HR RCT NO NO LENE LENE
MES for 8 conditions
Stable platform (E.O) AP 1 HR RCT NO NO LENE LENE
Stable platform (E.O) ML 1 HR RCT NO NO LENE LENE
Stable platform (E.C) AP 1 HR RCT YES YES LEOE LEOE
Stable platform (E.C) ML 1 HR RCT YES NO LEOE LENE
Dynamic platform (E.O) AP 1 HR RCT NO NO LENE LENE
Dynamic platform (E.O) ML 1 HR RCT NO NO LENE LENE
Dynamic platform (E.C) AP 1 HR RCT YES NO LEOE LENE
Dynamic platform (E.C) ML 1 HR RCT YES YES LEOE LEOE
Biodex Generated
Stability Indices
Involved limb at level 2 1 HR RCT YES YES LEOE LEOE
Involved limb at level 6 1 HR RCT YES YES LEOE LEOE
COP Values
COP Area (E.O) 3 HR RCTS YES, NO,
NO
YES, NO, NO CE CE
COP M/L (E.O) 2 HR RCTS NO, NO NO, NO MENE MENE
COP A/P (E.O) 2 HR RCTS NO, NO NO, NO MENE MENE
COP Total (E.O) 1 HR RCT YES N/A LEOE LEOE
A/P COP vel (E.O) 2 HR RCTS NO, YES NO, NO CE MENE
A/P COP vel (E.C) 1 HR RCT NO NO LENE LENE
M/L COP vel (E.O) 2 HR RCTS NO, NO NO, NO MENE MENE
M/L COP vel (E.C) 1 HR RCT YES YES LEOE LEOE
A/P COP sd (E.O) 1 HR RCT NO NO LENE LENE
A/P COP sd (E.C) 1 HR RCT NO NO LENE LENE
M/L COP sd (E.O) 2 HR RCTS NO, NO NO, NO MENE MENE
M/L COP sd (E.C) 1 HR RCT NO NO LENE LENE
M/L COP Max (E.O) 1 HR RCT NO NO LENE LENE
COP Area (E.C) 1 HR RCT NO NO LENE LENE
Range of COP AP (E.O) 1 HR RCT NO NO LENE LENE
Range of COP AP (E.C) 1 HR RCT NO NO LENE LENE
Range of COP ML (E.O) 1 HR RCT NO NO LENE LENE
Range of COP ML (E.C) 1 HR RCT NO NO LENE LENE
COP vel (E.O) 1 HR RCT N/A NO NAE LENE
COP vel (E.C) 1 HR RCT N/A NO NAE LENE
E.0. = eyes open
E.C. = eyes closed LEOE = limited evidence of effectiveness
HR RTC = high risk randomised controlled trial
CE = conflicting evidence
LR RTC = low risk randomized controlled trial
MENE = moderate evidence, no effectiveness
LENE = limited evidence, no effectiveness
NAE = no available evidence
S.I. = stability index
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dorsiflexion, as well as 15 and 30 degrees of plantarflex-
ion. Again group effects were not calculated in this
study.
Muscle Onset Latencies
Electromyography (EMG) has been used in the assess-
ment of neuromuscular control as it allows the timing
and degree of muscle activity to be determined during
functional tasks. Two high risk studies [22,31] looked at
muscle onset latencies in response to a sudden inversion
perturbation of the ankle joint. Based on the study by
Eils and Rosenbaum [22] which looked at muscle reac-
tion times (MRTs) in response to 30 degrees of sudden
inversion perturbation there is limited evidence of a
prolonged time effect for the peroneus longus (PL) and
peroneus brevis (PB) MRTs following 6 weeeks of pro-
prioceptive training. Whilst this finding was at odds
with the reduction in muscle onset latencies that was
anticipated, the authors did however report on a more
synchronised reaction of the PL and tibialis anterior
(TA) in stabilising the ankle joint after sudden perturba-
tion. Based on the same study there is limited evidence
of no time effect improvement for TA onset post intere-
vention. The authors failed to describe group effects.
BasedonthestudybyClarkeandBurden[31],which
recorded MRTs in response to a sudden 20 degree
inversion of the ankle via a trapdoor mechanism, there
Table 11 Results of studies per outcome
OUTCOME DESCRIPTION STUDIES TIME
EFFECT
GROUP
EFFECT
BEST EVIDENCE
SYNTHESIS (TIME)
BEST EVIDENCE
SYNTHESIS (GROUP)
Static Postural
Stability (cont.)
Time to Boundary
(TTB) Measures:
Abs. Min TTBML (E.O) 1 HR RCT NO NO LENE LENE
Abs. Min TTBML (E.C) 1 HR RCT YES YES LEOE LENE
Abs. Min TTBAP (E.O) 1 HR RCT NO NO LENE LENE
Abs. Min TTBAP (E.C) 1 HR RCT NO NO LENE LENE
Mean Min TTBML (E.O) 1 HR RCT NO NO LENE LENE
Mean Min TTBML (E.C) 1 HR RCT YES YES LEOE LENE
Mean Min TTBAP (E.O) 1 HR RCT NO NO LENE LENE
Mean Min TTBAP (E.C) 1 HR RCT YES YES LEOE LENE
SD Min TTBML (E.O) 1 HR RCT NO NO LENE LENE
SD Min TTBML (E.C) 1 HR RCT NO NO LENE LENE
SD Min TTBAP (E.O) 1 HR RCT NO NO LENE LENE
SD Min TTBAP (E.C) 1 HR RCT YES YES LEOE LENE
Total Distance
Travelled Measure
Involved limb 1 HR RCT NO NO LENE LENE
Dynamic Postural
Stability
SEBT Measures
Anterior 2 HR RCTS N/A, NO NO, NO LENE MENE
Posterior 1 HR RCT N/A NO N/A LENE
Lateral 1 HR RCT N/A YES N/A LEOE
Medial 1 HR RCT N/A NO N/A LENE
Anteromedial 1 HR RCT N/A NO N/A LENE
Anterolateral 1 HR RCT N/A NO N/A LENE
Posteromedial 2 HR RCTS N/A, YES YES, YES LEOE MENE
Posterolateral 2 HR RCTS N/A, YES YES, YES LEOE MENE
Mean of all 8 directions 1 HR RCT N/A YES N/A LEOE
Abs. Min = absolute minimum
Mean Min = mean minimum
SD Min = standard deviation of the minimum
TTBAP = time to boundary anteroposteriorly
TTBML = time to boundary mediolaterally
SEBT = star excursion balance test
HR RCT = high risk randomized controlled trial
LENE = limited evidence, no effectiveness
LEOE = limited evidence of effectiveness
MENE = moderate evidence, no effectiveness
E.0. = eyes open E.C. = eyes closed
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is limited evidence for time and group improvements for
both TA and PL reaction times following 4 weeks of
wobble board training.
Strength
Strength ratios have also been used to detect post training
improvements in subjects with CAI. Two high risk studies
looked at strength measures. Docherty et al [29] assessed
isometric dorisflexor and evertor strengths using a
handheld dynamometer after 6 weeks of resisted thera-
band exercises. Kaminski et al [32] looked at isokinetic
eversion/inversion (E/I) strength ratios after theraband
strengthening, proprioceptive training incorporating
“T-band kicks”, and a combination of both protocols. This
ratio expresses the viewpoint of the evertors acting con-
centrically to counteract the violent inversion mechanism
in an open kinetic chain, and/or the invertors acting
Table 12 Results of studies per outcome
OUTCOME DESCRIPTION STUDIES TIME
EFFECT
GROUP
EFFECT
BEST EVIDENCE
SYNTHESIS (TIME)
BEST EVIDENCE
SYNTHESIS (GROUP)
Joint Position
Sense (JPS)
Active JPS (NWB)
15° Inversion 1 HR RCT NO NO LENE LENE
20° Inversion 1 HR RCT YES YES LEOE LEOE
15° Inversion at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
Maximal Inversion 1 HR RCT NO NO LENE LENE
10° Eversion 2 HR RCTS NO, YES NO, NO CE MENE
10° Eversion at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
0° Neutral 1 HR RCT NO NO LENE LENE
0° Neutral at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
10° Dorsiflexion 1 HR RCT YES YES LEOE LEOE
20° Plantarflexion 1 HR RCT YES YES LEOE LEOE
Active JPS (WB)
Anterior 1 HR RCT NO N/A LENE NAE
Posterior 1 HR RCT YES N/A LEOE NAE
Lateral 1 HR RCT NO N/A LENE NAE
Medial 1 HR RCT NO N/A LENE NAE
Overall 1 HR RCT YES N/A LEOE NAE
Passive JPS (NWB)
15° Inversion 1 HR RCT NO NO LENE LENE
15° Inversion at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
Maximal Inversion 1 HR RCT NO NO LENE LENE
10° Eversion 1 HR RCT NO NO LENE LENE
10° Eversion at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
0° Neutral 1 HR RCT NO NO LENE LENE
0° Neutral at 25°
plantarflexion
1 HR RCT NO NO LENE LENE
10° Dorsiflexion 1 HR RCT YES N/A LEOE NAE
20° Dorsiflexion 1 HR RCT YES N/A LEOE NAE
15° Plantarflexion 1 HR RCT YES N/A LEOE NAE
30° Plantarflexion 1 HR RCT YES N/A LEOE NAE
NWB = non-weight bearing
WB = weight-bearing
HRRCT = high risk randomised control trial
LENE = limited evidence, no effectiveness
LEOE = limited evidence of effectiveness
CE = conflicting evidence
MENE = moderate evidence, no effectiveness
NAE = No available evidence
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Table 13 Results of studies per outcome
OUTCOME DESCRIPTION STUDIES TIME
EFFECT
GROUP
EFFECT
BEST EVIDENCE
SYNTHESIS (TIME)
BEST EVIDENCE
SYNTHESIS (GROUP)
Muscle Onset Latencies Muscle Reaction
Times
30° Tilt TA 1 HR RCT NO N/A LENE NAE
20° Inversion TA 1 HR RCT YES N/A LEOE NAE
30° Tilt PL 1 HR RCT YES N/A LEAE NAE
20° Inversion PL 1 HR RCT YES N/A LEOE NAE
30° Tilt PB 1 HR RCT YES N/A LEAE NAE
Strength Isometric Strength
Isometric
Dorsiflexion
1 HR RCT YES YES LEOE LEOE
Isometric Eversion 1 HR RCT YES YES LEOE LEOE
Isokinetic E/I
Ratios
Average Torque at
30°/sec
1 HR RCT NO NO LENE LENE
Peak Torque at 30°/
sec
1 HR RCT NO NO LENE LENE
Average Torque at
120°/sec
1 HR RCT NO NO LENE LENE
Peak Torque at
120°/sec
1 HR RCT NO NO LENE LENE
Muscle Fatigue
Median Power
Frequency TA
1 HR RCT NO NO LENE LENE
Joint Kinematics
Rearfoot Position 1 LR RCT NO NO LENE LENE
Shank Rotation 1 LR RCT NO NO LENE LENE
Shank/Rearfoot
Coupling
1 LR RCT YES YES LEOE LEOE
Frequency of Injury
Recurrence
Incidence at 1 year
follow up
1 HR RCT YES N/A LEOE NAE
Patient Perceived
Functional Stability
AJFAT 2 HR RCTS YES, YES YES, N/A MEOE LEOE
FADI 2 HR RCTS N/A, YES YES, YES LEOE MEOE
FADI-Sport 2 HR RCTS N/A, YES YES, YES LEOE MEOE
TA = tibialis anterior
MEOE = moderate evidence of effectiveness
PL = peroneus longus
AJFAT = ankle joint functional assessment tool
PB = peroneus brevis
FADI = foot and ankle disability index
LENE = limited evidence, no effectiveness
HR RCT = high risk randomised controlled trial
LEOE = limited evidence of effectiveness
LR RCT = low risk randomised controlled trial
MENE = moderate evidence, no effectiveness
NAE = no available evidence
LEAE = limited evidence, adverse effect
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eccentrically to slow the lateral displacement of the tibia in
a closed kinetic chain scenario. Based on the study by
Docherty et al [29] there is limited evidence of both time
and group effects for isometric dosiflexion and eversion
strengths following this type of neuromuscular training.
Based on the study by Kaminski et al [32] there is limited
evidence of neither time nor group effect for average or
peak torques calculated at 30 degrees/second and 120
degrees/second for any of the training groups.
Muscle Fatigue
It has been show that muscle fatigue can significantly
impair postural control [33,34]. Thus, it is plausible that
improvements in muscle strength and endurance
through training would improve stability. One high risk
RCT [23] looked at measures of median power fre-
quency (fmed) from an EMG signal to assess for
improvements in measures of muscle fatigue in the TA
and PL following either resisted strength training, pro-
prioceptive training, or a combination of both. Based on
this study there is limited evidence of neither time nor
group effect for improvements in measures of muscle
fatigue for any of the training groups.
Joint Kinematics
One low risk RCT [35] looked at joint kinematics whilst
walking and running on a threadmill. Kinematic mea-
sures of rearfoot inversion/eversion, shank rotation, and
the coupling relationship between these two segments
was analysed throughout the gait cycle whilst walking
and running. Based solely on this study there is limited
evidence of both time and group improvements for
improved shank/rearfoot coupling variability during
walking as measured by the deviation phase following 4
weeks of balance training. There is limited evidence of
neither time nor group effectiveness for improvement in
measures of rearfoot position, or shank rotation during
walking or running. Equally there is limited evidence of
no effect for time nor group improvements for shank/
rearfoot coupling whilst running following balance
training.
Frequency of Recurrence
Incidence of recurrence at one year follow up was
assessed by only one high risk RCT [22]. Based on this
study there is limited evidence of time effect following
the 6 week neuromuscular intervention. The authors did
not report on group effects.
Patient Perceived Stability
Four high risk studies looked at patient perceived stabi-
lity scales as an outcome measure. Two trials [21,31]
utilised the Ankle Joint Functional Assessment Tool
(AJFAT), to assess for the efficacy of 4 weeks of balance
training. Two further studies [7,8] used both the Foot
and Ankle Disability Index (FADI), and it’ssport’ssub-
section the FADI-Sport to assess for the effectiveness of
4 weeks of balance training on patient perceived
stability. The AJFAT is a 12 part questionnaire with the
overall score calculated by totalling the point values
from the 12 questions (maximum score = 48). The
higher the overall score the greater the perceived func-
tional ability of the involved ankle. The FADI is another
questionnaire used to quantify self reported disability in
subjects with CAI. The FADI contains 26 items related
to activities of daily living, and the FADI-Sport contains
8 items that evaluate perceived disability due to foot
and ankle injury in endeavours associated with physical
activity and sports participation.
Whilst the validity and reliablity of the AJFAT has yet
to be established, the reliability and sensitivity of both
components of the FADI have previously been reported
in subjects with and without FAI [36]. The study by
Clarke and Burden [31] looked at time effect only,
whereas that of Hale et al [7] looked at group effects
only. Hence based on the studies by Rozzi et al [21] and
Clarke and Burden [31] there is moderate evidence of
time effect improvement in AJFAT scores post neuro-
muscular training. Based solely on the study by Rozzi et
al [21] there is limited evidence for group effect. Based
on the studies by Hale et al [7], and McKeon et al [8]
there is moderate evidence of group effect for improve-
ments in both FADI and FADI-Sport scores respectively.
BasedpurelyonthestudybyMcKeonetal[8]thereis
limited evidence of time effect for improvements in
both the FADI and FADI-Sport scores.
Discussion
This review summarised the evidence for the effective-
ness of neuromuscular training on a variety of sensori-
motor and functional deficits in subjects with CAI. In
general, this overview revealed only moderate or limited
evidence in favour of neuromuscular training, according
to outcome measures of static and dynamic postural sta-
bility, active and passive JPS, isometric strength, muscle
onset latencies, shank-rearfoot coupling, patient per-
ceived stability, and frequency of recurrence. However,
for none of the outcome measures strong evidence in
favour of neuromuscular training was found.
Theaforementionedevidenceisbasedonalimited
number of studies (n = 14), with a maximum of eight
studies per outcome measure. In these studies neuro-
muscular training was defined as either proprioceptive
drills, strength training, or a combination of both. How-
ever, the specific mechanisms of training were quite var-
ible in terms of the mode, frequency, and the duration
of the training period. Training protocols varied from 1
session per week for 6 weeks [22], to 5 times per week
for 10 weeks [6]. In addition, heterogeneity among the
studies was observed concering the study populations in
terms of the presence or absence of concommitant MI,
and outcome assessment. Furthermore, all but one of
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the studies included in the review were assessed as hav-
ing a high risk of bias. Therefore, we refrained from sta-
tistical pooling of the results of the individual studies,
and instead conducted a best evidence synthesis.
The assesment of risk of bias resulted in almost 93%
of the studies identified as having high risk. The thresh-
old to differentiate between low and high risk of bias
studies was based on the methodological study of van
Tulder et al [14] in which they assessed the validity of
the Cochrane Collaboration’s tool for assessing the risk
of bias in trials with back-pain interventions. In this
study a threshold of 50% or less was associated with
bias, therefore similar to van Rijn et al [12] it was
decided that studies with 6 or more points were
regarded as high risk studies. Critical items in the risk
of bias assessment were items on randomisation (item
1), allocation concealment (item 2), and blinding (items
3,4, and 5).
None of the studies scored positively on patient or
care provider blinding, which is devoted to the fact that
the setting of physical therapy often does not lend itself
to the blinding of patients or care givers. All of the stu-
dies scored “unclear"on the item concerning compliance,
and in 86% of the studies it was unclear whether or not
co-interventions were avoided. Hence, these studies are
more susceptible to selection bias, and as a conse-
quence, the generalisability of the results in this review
is adversely effected.
There are a number of plausible explanations to
account for the variability in findings among certain stu-
dies, and the failure of others to produce statistically sig-
nificant results. In the studies pertaining to static joint
stability [6-8,10,20-24] measures taken in the absence of
visual cues tended to producemoremeaningfulresults
than those where visual input was retained. Vision is an
extremely important sense for the control of balance. It
is believed that even when somatosensory input is dis-
rupted due to injury, visual information can provide an
adequate amount of feedback to compensate for deficits
in the central pathways or the vestibular system [37,38].
Hence, it was perhaps unsurprising that when this com-
pensatory mechanism is removed through closing the
eyes, deficits in the sensorimotor system become more
apparent. This may be an important consideration for
researchers to bear in mind when selecting outcome
measures in the future.
Another possible reason for the inconsistent findings
among studies is the lack of sensitivity of the measures
chosen to detect post training improvements. Many of
the studies in the review used traditional COP excursion
values to assess for interventional efficacy [6-8,10,22-24].
Unfortunately, these measures have been shown not to
be particularly sensitive in detecting CAI related pos-
tural control deficits, when compared to TTB measures
[17]. TTB measures have also been shown to be more
sensitive than traditional COP excursion (COPE) mea-
sures in detecting post training improvement in subjects
with FAI [8]. These findings may go some way towards
explaining why COPE measures have failed to show sig-
nificant post-training improvements in a number of the
studies reviewed. In many of the other studies particu-
larly those relating to strength and JPS [20,22,29,30,32],
failure to reveal significant post training effects may be
best understood from a mode specificity standpoint,
wherebythedisparitybetween training protocols and
the outcomes used to assess for efficacy appears to be
too great. Researchers examining the area of CAI need
to recognise that when subjects are trained using a spe-
cific protocol, outcomes that closely resemble the inter-
vention are best suited to assess for treatment effect.
Relating to the studies looking at muscle onset latencies
[22,31], differences in outcome can be accounted for to
some degree due to the different algorithms used to cal-
culate muscle onset latencies. Greater standardisation of
testing protocols is required in order for meaningful
comparisons to be made.
Furthermore, the majority of studies included in the
review examined the efficacy of a specific treatment
strategy such as balance training or strength training
in isolation. Due to the multi-faceted nature of CAI
which cannot be adequately explained through the
dichotomy of MI and FI [5], a more comprehensive
treatment approach combiningstrengthening,proprio-
ceptive training, and functional retraining may be
more effective in improving lower extremity function
and preventing recurrent injury. Addressing local
arthrokinematic impairments may also help elicit
greater improvements for various outcomes. Following
on from this, it may then be beneficial to develop a
treatment or impairment based classification system
that addresses the multi-factorial nature of the condi-
tion. Classification of individuals with CAI into differ-
ent groups based on impairments or treatment
response may lead to more efficient conservative man-
agement in the future.
Only one of the studies reviewed [22], looked at recur-
rence rates at one year follow-up. Hence there is cer-
tainly a need for more studies to examine interventional
efficacy in the longer term. It is of paramount impor-
tance to know if immediate post-training improvements
are maintained, and whether or not these improvements
carry over to a long-term reduction in symptoms and
prevention of injury recurrence. Further research is
necessary before any meaningful conclusions can be
drawn regarding the efficacy for neuromuscular training
leading to improvements in joint kinematics and muscle
fatigue. The findings to date relating to patient per-
ceived functional stabilitylookpromising,though
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further reseach will be required to corroborate these
preliminary results.
Although deemed to be outside the scope of this
review a number of authors have advocated the use of
adjuctive therapies such as taping and stochastic reso-
nance stimulation combined with neuromuscular train-
ing. Preliminary findings indicate earlier and superior
results than training alone [6,10]. Such additional inter-
ventions certainly warrant further investigation. Thera-
pies providing a greater treatment effect than
neuromuscular training alone may well have implica-
tions for improved function, a reduction in injury recur-
rence, and reduced treatment costs.
Conclusion
In conclusion, this review showed moderate or limited
evidence of effectiveness in favour of neuromuscular
training, according to the outcome measures of static
and dynamic postural stability, active and passive JPS,
isometric strength, muscle onset latencies, shank-rear-
foot coupling and injury recurrence rates. For none of
the outcome measures strong evidence of effectiveness
was found. However, only a small number of studies
[14] were eligible for inclusion in the review. Most stu-
dies were assessed as having a high risk of bias, and
most studies were lacking power. Therefore we recom-
mend conducting further high-quality RCTs with suffi-
cient power to assess for the effectiveness of
neuromuscular training in subjects with CAI. Such stu-
dies should also consider the importance of mode speci-
ficity of training, and the implementation of outcome
measures with adequate sensitivity to detect interven-
tional effect
Additional material
Additional file 1: Search terms. Search terms used for the identification
of studies.
Additional file 2: Source of risk bias. Items used for the assessment of
risk bias.
Author details
1
Mount Carmel Hospital, Dublin, Ireland.
2
School of Public Health,
Physiotherapy and Population Science, University College Dublin, Dublin,
Ireland.
3
Institute for Sport and Health, University College Dublin, Dublin,
Ireland.
Authors’contributions
JOD and ED conceived and performed the study and drafted the
manuscript. All authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 17 February 2011 Accepted: 22 September 2011
Published: 22 September 2011
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doi:10.1186/1758-2555-3-19
Cite this article as: O’Driscoll and Delahunt: Neuromuscular training to
enhance sensorimotor and functional deficits in subjects with chronic
ankle instability: A systematic review and best evidence synthesis.
Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology 2011 3:19.
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