The implementation of resistance training principles in exercise interventions for lower limb tendinopathy: A systematic review

Abstract

Objectives: The primary purpose of this systematic review is to examine the literature on resistance training interventions for lower limb tendinopathy to evaluate the proportion of interventions that implemented key resistance training principles (specificity, progression, overload, individualisation) and reported relevant prescription components (frequency, intensity, sets, repetitions) and reported intervention adherence. Design: Two reviewers performed a qualitative systematic review after screening titles and abstracts based on eligibility criteria. Identified papers were obtained in 2 full text, with data extracted regarding the implementation of resistance training principles. Included articles were evaluated by the Cochrane risk of bias tool, with a scoring tool out of 10 used for implementation and reporting of the 5 key principles. Scientific databases were searched in November 2020 and included Medline, CINAHL, AMED, and Sportsdiscus. Results:52 randomised controlled trials investigating resistance training in five different lower limb tendinopathies were included. Although most studies considered the principles of progression (92%) and individualisation (88%), only 19 studies (37%) appropriately described how this progression in resistance was achieved, and only 18 studies (35%) reported specific instruction on how individualisation was applied. Adherence was considered in 27 studies (52%), with only 17 studies (33%) reporting the levels of adherence. In the scoring criteria, only 5 studies (10%) achieved a total maximum score of 10, with 17 studies (33%) achieving a maximum score of 8 for implementing and reporting the principles of specificity, overload, progression and individualisation. Conclusion: There is meaningful variability and methodological concerns regarding the application and reporting of resistance training principles, particularly progression and individualisation, along with intervention adherence throughout studies. Collectively, these findings have important implications for the prescription of current resistance training interventions, including the design and implementation of future interventions for populations with lower limb tendinopathies.

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This article was last modified on December 28th, 2020.
Received: 28 December 2020
Supplementary materials:
For correspondence:
Ianburton_10@hotmail.co.uk
The implementation of resistance training principles in
exercise interventions for lower limb tendinopathy: A
systematic review
Ian Burton MSc, CSCS.
Physiotherapist, Angus HSCP, NHS Tayside, Dundee, United Kingdom
Please cite as: Burton, I. (2020). The implementation of resistance training
principles in exercise interventions for lower limb tendinopathy: A systematic
review. SportRxiv doi: 10.31236/osf.io/8etvu
ABSTRACT
Objectives: The primary purpose of this systematic review is to examine the
literature on resistance training interventions for lower limb tendinopathy to
evaluate the proportion of interventions that implemented key resistance training
principles (specificity, progression, overload, individualisation) and reported
relevant prescription components (frequency, intensity, sets, repetitions) and
reported intervention adherence.
Design: Two reviewers performed a qualitative systematic review after screening
titles and abstracts based on eligibility criteria. Identified papers were obtained in

2
full text, with data extracted regarding the implementation of resistance training
principles. Included articles were evaluated by the Cochrane risk of bias tool, with
a scoring tool out of 10 used for implementation and reporting of the 5 key
principles. Scientific databases were searched in November 2020 and included
Medline, CINAHL, AMED, and Sportsdiscus.
Results: 52 randomised controlled trials investigating resistance training in five
different lower limb tendinopathies were included. Although most studies
considered the principles of progression (92%) and individualisation (88%), only
19 studies (37%) appropriately described how this progression in resistance was
achieved, and only 18 studies (35%) reported specific instruction on how
individualisation was applied. Adherence was considered in 27 studies (52%), with
only 17 studies (33%) reporting the levels of adherence. In the scoring criteria,
only 5 studies (10%) achieved a total maximum score of 10, with 17 studies
(33%) achieving a maximum score of 8 for implementing and reporting the
principles of specificity, overload, progression and individualisation.
Conclusion: There is meaningful variability and methodological concerns
regarding the application and reporting of resistance training principles,
particularly progression and individualisation, along with intervention adherence
throughout studies. Collectively, these findings have important implications for the
prescription of current resistance training interventions, including the design and
implementation of future interventions for populations with lower limb
tendinopathies.
Introduction
Recent evidence has highlighted the enormous global burden of musculoskeletal
disorders, with approximately 1.3 billion prevalent cases and 121,300 deaths due to
musculoskeletal disorders in 2017, as well as 138.7 million disability-adjusted life
years (Safiri et al. 2020). Tendinopathies of the lower limb represent some of the
most common musculoskeletal disorders, with a high prevalence in both the
general sedentary population and athletic individuals (Minetto et al. 2020;

3
Ganestam et al. 2016; Riel et al. 2019). Prevalent tendinopathies such as Achilles,
patellar and plantar heel cause chronic pain, disability, functional and activity
limitations and impaired quality of life (Abat et al. 2017). Despite a range of
treatment options being available, exercise and particularly different forms of
resistance training are most often implemented and recommended, however only
moderate long-term effectiveness for improving pain and function has been
demonstrated (Girgis and Duarte, 2020; Cardoso et al. 2019; Riel et al. 2019;
Dimitrios 2015). Recently, the extent of heterogeneity within tendinopathy
populations has been highlighted, with a host of individual factors been shown to
influence risk and onset of tendinopathy, as well as outcomes to treatment such
as resistance training (Steinmann et al. 2020). Therefore, the response of
individuals to exercise interventions can be diverse and multifactorial, due to the
interactions of a plethora of factors (Ferreira et al. 2020; Dean et al. 2017).
Response to resistance training may be dependent on tendinopathy type and stage
on the continuum, duration, age, individual intrinsic and extrinsic factors as well
as exercise parameters such as the type, dose, duration, frequency, volume and
intervention adherence (Barratt et al. 2017; Morrissey 2015). Therefore, it is
plausible that applying a generic and standardised resistance training approach to
a largely heterogenous tendinopathy population may reduce the full potential
utility of the approach for improving outcomes in tendinopathy.
Resistance training interventions are typically based on the key core resistance
training principles of specificity, overload and progression, which when applied
appropriately can ensure sufficient challenge and adaptation of the human
neuromuscular system (Fleck 2011; Fleck and Kraemer 2014; Haff and Triplett
2015). Although not considered a core principle of resistance training, the principle
of individualisation has recently received increased attention and when exercise
interventions are individually tailored, outcomes have been shown to be improved
compared to standardised interventions (Jones et al. 2016; Mann et al. 2014;
Borressen and Lambert 2009). Individualisation of exercise prescription may also
be highly relevant in tendinopathy due to its heterogenous nature, and as such
leading tendinopathy researchers and clinicians have stressed the importance of
individualising exercise treatments to improve outcomes (Abat et al. 2017;
Silbernagel et al. 2014). Implementing key resistance training principles can help

4
to appropriately manipulate key training variables such as training load, volume
and duration, which may impact on clinical outcomes (Hasani et al. 2020).
Consequently, given the importance of optimising the key resistance training
principles within tendinopathy treatment interventions, determining the extent to
which these scientific principles are currently implemented may be considered
integral for guiding further research and clinical recommendations for
tendinopathy (Malliaras et al. 2015). It is essential that the scientific principles of
resistance training are correctly applied and reported within interventions, in order
to achieve optimal exercise dosages and stimulus, and to allow for an appropriate
evaluation of their feasibility and effectiveness within tendinopathy populations.
Therefore, a systematic evaluation of the individual components, principles and
prescription of resistance training within the current lower limb tendinopathy
literature is warranted.
Despite the plethora of systematic reviews examining the effectiveness of exercise
interventions for lower limb tendinopathies, including resistance training, there
have been no comprehensive reviews examining the application and reporting of
key resistance training principles within interventions (Clifford et al. 2020; Van
der Vlist et al. 2020; Vander Doelen et al. 2020; Lim et al. 2018; Malliaras et al.
2013; Murphy et al. 2019; Babatunde et al. 2018; Challoumas et al. 2019). It
could be considered a highly important objective to determine the extent to which
the key scientific training principles have been implemented due to inadequate
long-term outcomes of resistance training for lower limb tendinopathies
(Silbernagel 2014; Riel 2019). Despite this importance, the application of key
principles has not been adequately investigated and reported in previous
systematic reviews. An understanding of the current adoption of resistance
training principles may present an avenue for improving the implementation of
key principles appropriately, which may improve the utility of resistance training
interventions and long-term outcomes for tendinopathy patients.

5
Objective
The primary purpose of this systematic review was to examine the current
literature on resistance training interventions for lower limb tendinopathies and
evaluate the proportion of studies that implemented key resistance training
principles (specificity, progression, overload, individualisation) and reported
relevant prescription components (frequency, intensity, sets, repetitions) and
reported adherence.
METHODS
Design
This was a qualitative systematic review with a priory eligibility criterion
established and applied to the search strategy prior to conducting literature
searches.
Eligibility criteria
This review considered randomised controlled trials (RCTs) only for eligibility for
inclusion. To be considered for inclusion, RCTs must have investigated a primary
resistance training intervention, either in isolation or combined with another
treatment in adults with lower limb tendinopathy. Specific tendinopathies included
patellar, Achilles, and gluteal tendinopathy, posterior tibial tendon dysfunction and
plantar heel pain. Studies published in peer-reviewed journals and in English
language were considered for inclusion.
Data sources

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Scientific databases were searched in November 2020 and included Medline,
CINAHL, AMED, Sportsdiscus. Search terms related to the included lower limb
tendinopathies and resistance training were entered in different combinations as
Medical Subject Heading (MESH) terms and keywords where appropriate. All terms
were applied and modified specifically to each database. Manual searches of
reference lists from other systematic reviews of resistance training interventions
for lower limb tendinopathy were conducted to retrieve any additional articles.
Databases were searched from 2000 to 2020. The year 2000 was chosen to ensure
seminal work is not missed as clinical research in this area began around this time.
Including findings from studies published more than 20 years ago may not be
relevant due to advances in both research methodologies and clinical practice for
tendinopathy. Studies published in a language other than English were only
included if a translation was available as translation services are not available to
the authors.
Article selection
Two reviewers independently screened the title and abstracts of every citation
found in the literature search to decide eligibility, with any disagreements resolved
through discussion. Identified articles considered relevant were obtained in full-
text and independently assessed against the eligibility criteria by both reviewers.
Any disagreements were resolved through discussion and consensus with an
independent third reviewer if required. The search results are reported in
accordance with the PRISMA guidelines and are presented in figure 1, which
outlines the results of the comprehensive searches.
Data extraction
Relevant data from included studies were systematically extracted into pre-
determined templates under the following headings: population, tendinopathy
diagnosed, sample size, outcome measures, outcomes (table 3), and details on

7
resistance training principles and the training interventions used (table 4). The
relevant details from each study were independently extracted and rated by both
reviewers according to the definitions of each resistance training principle, as
outlined in tables 1 and 2. Appropriate inclusion and reporting of a training
principle were assigned a ‘Y’, with ‘NR’ assigned if the principle was not reported
in the study. If it was unclear whether a training principle was appropriately
included, ‘UC’ was assigned to the principle. Characteristics of each training
intervention according to the FITT principles of frequency, intensity, time and type
of exercise, together with details on specific exercises used, prescribed repetitions
and sets were also extracted. An overview of extracted details on the description
of components of training interventions and their principles is provided in table 4.
Each study was assigned a separate score rating for each of the key resistance
training principles and adherence, based on application of the principle within the
study design and for adequate reporting of the principle within the study.
Appropriate application of each principle was assigned a score of 1, and 0 was
applied for inadequate description of the principle or if it was not used in the study.
A total score for the resistance training principles and adherence was obtained for
each study in the review, with a maximum score of 10 available per study. Details
of the scoring criteria are provided in table 2.
Risk of bias
Included studies were critically appraised by two independent reviewers at study
level for methodological quality in the review using the standardized Cochrane risk
of bias tool on Covidence. Any disagreements that arose between the reviewers
were resolved through discussion or with a third reviewer. The results of critical
appraisal are reported in narrative form, and in a graph. All studies meeting the
inclusion criteria, regardless of their methodological quality, underwent data
extraction and synthesis and were included in the review. Seven criteria were
appraised for RCTs. Item three which pertained to blinding was included but not
considered highly relevant in final scoring and grading of recommendations, given
that interventions could not be blinded. Therefore, a maximum high-quality score
of 6 or 7 could be achieved, with all included studies scoring at least 4/7, which
was considered a moderate quality score (figure 2).

8
Table 1: Resistance training principles and training intervention criteria
assessed
Principle
Criteria for this review
Specificity: Training and desired
adaptations should be specific to the
tendinopathy and relevant to desired
outcomes
Appropriate population targeted and
intervention designed to improve
primary outcome
Progression: to allow for continuous
adaptations, resistance or load must
be increased providing a greater stress
to the body
Training intervention was stated to be
progressive with gradual increases in
frequency, sets, repetitions, resistance
or loading throughout intervention
Overload: for the intervention to
improve strength, greater than normal
stress and training volume must occur
above current training levels
Interventions included baseline
strength testing or rationale that
intervention was of sufficient intensity
and volume relative to baseline
capacity
Individualisation: Training is tailored to
the individual to allow for consideration
of individual factors and training
response
Training intervention considered
methods to individually tailor exercises
stimulus based on an individual’s own
factors or training response
Component of training
Description
Frequency
How many times per week or day
Intensity
Measurement method: RM, %RM, RPE,
pain level
Time
Duration of session
Sets
How many sets of each exercise
Repetitions
How many repetitions of each exercise
or target number of repetitions
Exercise selection
Outline and description of specific
exercises used in intervention
Adherence
Was adherence to the training
intervention monitored and reported?

9
Table 2: Scoring of the application and reporting of key training principles
Principle/
criterion
Description
Score
Specificity
Design: have the
authors designed the
intervention to achieve
desired outcomes? 1/10
Reporting: have the
authors adequately
described the
intervention specificity?
1/10
2/10
Overload
Design: have the
authors appropriately
manipulated training
variables to achieve
desired outcomes? 1/10
Reporting: have the
authors adequately
described the
intervention training
variables? 1/10
2/10
Progression
Design: have the
authors appropriately
manipulated training
variables to adequately
progress the
intervention? 1/10
Reporting: have the
authors adequately
described how
intervention progression
was achieved and
assured? 1/10
2/10
Individualisation
Design: have the
authors appropriately
manipulated training
variables to adequately
individually tailor the
intervention? 1/10
Reporting: have the
authors adequately
described how
individually tailoring the
intervention was
achieved and assured?
1/10
2/10
Adherence
Design: have the
authors appropriately
designed and described
methods for monitoring
adherence? 1/10
Reporting: have the
authors adequately
reported individual
adherence to training
and training dose
achieved? 1/10
2/10

10
Figure 1: PRISMA study flow diagram
From: Moher D, Liberati A, Tetzlaff J, Altman DG, The PRISMA Group (2009). Preferred Reporting Items for Systematic
Reviews and Meta-Analyses: The PRISMA Statement. PLoS Med 6(6): e1000097. doi:10.1371/journal.pmed100009
Figure 2: Risk of bias summary
Number of additional records
identified through other sources
(N=2)
Number of records identified
through a systematic search
(N=6188)
Number of records after duplicates
removed (N=4960)
Number of records
screened (title and
abstract) (N=4960)
Number of records
excluded (N=4772)
Number of full-text
articles assessed for
eligibility (N=188)
Number of articles
excluded based on study
design (N=136)
Number of articles included
(N=52)
Number of articles
assessed for quality
(N=52)
Number of articles
excluded on critical
appraisal (N=0)
Identification
Screening
Eligibility
Included

11

12

13
Figure 3: Risk of bias graph
Data synthesis
The results from extraction are presented in a narrative synthesis and a summary
of findings was tabulated (table 3) and included study characteristics, sample size,
duration and outcomes together with a summary of the key training principles.
The application of training components such as specific exercises, repetitions, sets
and intensity is included in table 4. The total number of studies that applied each
training principle and reported intervention components was calculated into
percentages based on the proportion of studies reporting a principle relative to
the total number of included studies.
RESULTS
Study characteristics
An outline of the characteristics of included studies, such as intervention groups,
sample size and outcomes are presented in table 3, with resistance training
principles presented in table 4. A total of 6188 records were identified in the
comprehensive literature search, with 188 selected for full-text review (figure 1).
A total of 52 RCTs involving 2487 participants met the review inclusion criteria,

14
with 136 studies being excluded due to wrong study design, mainly not being
RCTs. Achilles tendinopathy was the most common tendinopathy investigated (26
studies), followed by patellar (16), plantar heel (4), gluteal (3), and tibialis
posterior (3). All studies investigated a resistance training intervention, with most
doing so in isolation, while 4 studies investigated resistance training combined
with another intervention, either corticosteroid injection or orthoses. Eccentric
resistance training (40 studies) was the most common resistance training type
investigated, with concentric (3), isometric (3), isotonic (3) heavy slow resistance
(7) and combined or general training approaches (4) also investigated. The
duration of training interventions ranged from 4 to 26 weeks, with 44 studies
(85%) using a 12-week intervention. All studies adopted outcome measures which
assessed pain and function outcomes of the interventions, with other measures
including quality of life and tendon structure through ultrasonography. Pain was
measured by VAS scales in 26 studies, and NRS in 3 studies. The VIS-A was used
to measure function in 18 studies, VISA-P in 10 studies and the FFI in 5 studies.
Cochrane risk of bias scores ranged from 1-6, with no studies achieving a
maximum score of 7. This was largely since resistance training interventions
cannot be blinded, therefore all studies had high risk of bias for this criterion.
Therefore, if a score of 6 was considered the maximum score, only 7 of 52 studies
achieved this score, highlighting the high risk of bias throughout many included
studies.
Application of key principles
An overview of the application of key resistance training principles within included
studies is presented in table 4. All studies (100%) appropriately implemented the
principle of specificity by targeting the resistance training to the pathological
tendon with the aim of improving pain and function. The principle of overload was
appropriately applied in 48/52 studies (92%), in the form of progressively
increasing resistance throughout the intervention. The principle of progression
was implemented in 48/52 studies (92%), however only 19 studies (37%)
appropriately described how this progression in resistance was achieved and with
what load, most commonly with small increases in external weight. Increased

15
resistance was applied by using a progressively loaded backpack in 31 studies
(60%), with 5 studies (10%) reporting using weight machines, and 4 studies using
resistance bands (8%). Incremental increases in resistance ranged from 0.9-5kg,
with 5kg being the most common as reported in 12 studies (23%). The principle
of individualisation through individually tailoring training was applied in 46/52
studies (88%), with 39 studies tailoring training based on pain response, four on
exercise technique, two on as much volume as possible per session and one study
used a BORG scale to tailor intensity. Of the studies that considered
individualisation, only 18 studies (35%) reported specific instruction on how this
was applied, such as by following pain scales to a certain level before adjusting
resistance. Adherence was considered in 27 studies (52%), most commonly in the
form of an exercise adherence diary. However, only 17 studies (33%) reported
the levels of adherence to the prescribed training intervention. In the scoring
criteria, a maximum score of 8 was possible for application and reporting of
resistance training principles only, and a total score of 10 with adherence included.
Only 5 studies (10%) achieved a total maximum score of 10, with 17 studies
(33%) achieving a maximum score of 8 for implementing and reporting the
principles of specificity, overload, progression and individualisation.
Reporting of resistance training components
All but one study failed to report the frequency of training sessions (98%).
Frequency ranged from 2 to 7 days per week, and 2 to 14 sessions per week. All
but two studies (96%) failed to report the intensity of the prescribed training
intervention. Intensity was prescribed either using a percentage of 1 repetition
maximum (RM) or most commonly as a target RM for a session, such as 10-15
RM. Although the duration of the entire intervention was reported in all studies
(100%), the duration of each session was only reported in 7 studies (13%). All,
but two studies (96%) reported the number of sets and repetitions of exercise.
Sets ranged from 1-12, with one study including as many sets as possible (Riel et
al. 2019), and repetitions per set ranged from 3-30, with one study including as
many repetitions as possible (Stevens and Tan 2014). All studies reported the
specific exercises used, with eccentric or isotonic heel raises being implemented

16
in 33 studies (63%), with 13 studies using eccentric decline squats (25%). The
most reported resistance training prescription throughout the interventions was
the parameters of the ‘Alfredson’ protocol, with 25 studies (48%) using the
original protocol or slight modifications from it. The parameters of the Alfredson
protocol include training twice per day, seven days per week, with 6 sets of 15
repetitions, totalling 180 repetitions per day, progressed with increased resistance
by adding weight to a backpack as able. The protocol involves two variations of a
standing heel raise exercise performed on a step, one performed with the knee
straight to target the gastrocnemius and the other with the knee flexed to target
the soleus muscles (Alfredson 1998).
Discussion
The primary purpose of this systematic review was to examine the current
literature on resistance training interventions for lower limb tendinopathies and
evaluate the proportion of studies that implemented key resistance training
principles (specificity, progression, overload, individualisation) and reported
relevant prescription components (frequency, intensity, sets, repetitions) and
reported adherence. A total of 52 RCTs investigating resistance training in five
different lower limb tendinopathies were included. The principles of specificity,
overload, progression and individualisation were applied and reported to varying
degrees throughout studies, along with consideration of exercise adherence.
Although most studies considered the principles of progression (92%) and
individualisation (88%), only 19 studies (37%) appropriately described how this
progression in resistance was achieved, and only 18 studies (35%) reported
specific instruction on how individualisation was applied. Adherence was
considered in 27 studies (52%), with only 17 studies (33%) reporting the levels
of adherence to the prescribed training intervention, which raises significant
concerns regarding the levels of exercise dosage achieved within studies. In the
scoring criteria, only 5 studies (10%) achieved a total maximum score of 10, with
17 studies (33%) achieving a maximum score of 8 for implementing and reporting
the principles of specificity, overload, progression and individualisation. There is
therefore meaningful variability and methodological concerns regarding the

17
application and reporting of resistance training principles, particularly progression
and individualisation, along with intervention adherence throughout studies.
Collectively, these findings have important implications for the prescription of
current resistance training interventions, including the design and implementation
of future interventions for populations with lower limb tendinopathies.
Since the publication of the Alfredson eccentric protocol for Achilles tendinopathy
in 1998, eccentric resistance training has become the dominant conservative
intervention strategy for lower limb tendinopathies over the last two decades
(Malliaras et al. 2013). The Alfredson protocol has also been modified for patellar
tendinopathy in several studies, in the form of an eccentric decline squat protocol
(Visnes et al. 2007; Young et al. 2005). Although eccentric training has positive
effects in treating tendinopathies, there is currently no strong evidence to suggest
that decreasing or eliminating concentric actions from the stretch-shortening cycle
is appropriate when treating chronic tendinopathies (Couppé et al. 2015; Malliaras
et. 2013). However, eccentric only training has shown better results when
compared with concentric only, for Achilles (Mafi et al. 2001), and patellar
tendinopathy (Jonsson and Alfredson 2005). Systematic reviews have evaluated
the evidence for eccentric resistance training, concluding that high-quality
evidence is lacking despite positive clinical outcomes in lower limb tendinopathies
(Mendonca et al. 2020; Girgis et al. 2020; Murphy et al. 2019: Lim and Wong,
2018). Despite Alfredson’s initial high success rate with an athletic cohort, it is
apparent from the evidence that not all patients have positive clinical outcomes
from isolated eccentric training. Sayana et al. (2007) found that 45% of patients
were considered to have failed treatment with eccentric training based on pain
and function outcomes, indicating that it may not be suitable for all patients.
More recently, Heavy Slow Resistance Training (HSRT) with heavy-load
concentric-eccentric contractions, has become more widespread in research and
clinical practice (Couppe et al. 2015). This method was first successfully
implemented in patellar tendinopathy (Kongsgaard et al. 2009) and later
investigated with positive outcomes in Achilles tendinopathy (Beyer et al. 2015)
and Plantar heel pain (PHP) (Rathleff et al. 2015) based on the same loading

18
principles and volume progression. Whereas the Alfredson eccentric protocol
stipulates a strict protocol of 180 repetitions daily, HSRT adheres more to scientific
training principles, such as progressive increases in load and volume and increased
rest periods. Recent evidence suggests that HSRT may have superior clinical
outcomes compared to isolated eccentric training interventions and leads to
greater patient satisfaction in treating lower limb tendinopathies (Murphy et al.
2019; Beyer et al. 2015; Kongsgaard et al. 2009). Despite this, evidence suggests
that even HSRT protocols do not reach intended dosage levels and may require
better loading and progression methods and a more individualised approach rather
than a standardised protocol (Riel et al. 2019).
The finding from this review that almost half of studies (48%) adopted the
parameters of the Alfredson protocol, which involves training twice per day, seven
days per week, with 6 sets of 15 repetitions, totalling 180 repetitions per day, is
particularly concerning. Training twice per day with such a high volume does not
follow current scientific resistance training recommendations, to achieve optimal
exercise dosage, recovery, tendon and physiological adaptations required to
improve clinical outcomes. The overload principle speaks to the necessity to stress
biological tissues beyond their current thresholds to increase tolerance to
subsequent stresses and avoid future injuries. Greater load tolerance can be
achieved by training at higher loads, which also has positive effects on remodeling
of the degenerated tendon (Kulig 2009). However, the Alfredson protocol for
example involves training twice daily for 12 weeks, meaning it is unlikely high
loads are being achieved. It is reccommended that no more than 3 high-intensity
training sessions should be undertaken within a week in the recovering tendon, to
allow adequate recovery and collagen synthesis (Malliaras et al. 2015; Magnussen
et al. 2009). Adequate rest periods are required in training protocols for tendon
adaptation in relation to anabolic and catabolic processes involved in tendon
remodelling (Waugh 2018). Resistance training for longer than 12-weeks may also
be necessary, in order to gain sufficient adaptation and positive results for lower
limb tendinopathies (Sussmilch-Leitch et al. 2012). The dosage (e.g., number of
repetitions, days per week and duration of a contraction) and type of exercise are
important characteristics of an exercise program, with loads as high as 80% of 1
repetition maximum (RM) having been used for isometric (80% 1RM) and isotonic

19
exercises (80% 8RM) (Van Ark et al. 2016). Beneficial effects from rehabilitation
for tendons require high load per repetition. Furthermore, a high percentage of
RM in leg extension exercises has been shown to improve muscle strength and
neural activation. However the precise mechanism of effect, optimal dosage and
loading strategy has not yet been determined and further research is required
(Van Ark et al. 2016).
There is currently little consensus regarding which variables might influence the
outcome of training, including whether training should be painful, home- versus
clinic-based training, the speed of the exercise, training duration, and progression
methods (Rompe et al. 2009). Large randomized controlled trials that consider
these parameters and include blinded assessors and extended follow-up periods
are warranted. Resistance training at a high intensity level of training, with
gradual increases in loading, are required to create positive effects on both the
muscle and tendon. Although the importance of mechanical loading through
exercise in patients with tendinopathy is well established, the optimal exercise
protocol contents and loading dosages require further investigation and may
include aspects of motor control, proprioception, strength, malalignment,
flexibility, kinetic chain and plyometric strength (Silbernagel 2007). The effects of
different loading strategies need to be investigated in tendinopathy before they
can be recommended in clinical practice, and findings in one type of tendinopathy
may not necessarily be generalisable to others (Riel 2018). As previous research
on lower limb tendinopathies has not found superiority of one specific resistance
training type, the long‐term effects of different loading programs in tendinopathy
remain to be investigated (Riel 2018).
As recognised by Purdam et al. (2004) there is a question of whether most of the
published studies are offering strength training, or may they be better described
as active stretching with relative low intensity eccentric actions (Abat et al. 2017).
It seems that published works on eccentric protocols do not offer true strength
training and it might be that only HSRT develops the minimum level of load and
tension to identify them as strength training based on scientific training principles.
Recent evidence suggests that an intensity threshold above 70% of maximum is

20
required to cause adaptations in tendon properties, including mechanical, material
and morphological tendon changes (Arampatzis et al. 2020; Bohm et al. 2015).
However, with the high repetition volume and inadequate loading in current
protocols, it is unlikely this intensity is being achieved, which may be related to
poor outcomes. Performing very slow repetitions (often 6-8 seconds) at a high
repetition volume, may also lead to reduced intensity. Perhaps a better approach
may be to perform less repetitions at a higher load with increased sets while
maintaining the slow tempo implemented in HSRT, such as the approach known
as ‘cluster training’ which could help maintain sufficient intensity and volume
(Davies et al. 2020). In conjunction with decreased repetitions and increased
loading intensity, autoregulation or self-selection of within-session load may also
account better for the principle of individualisation and allow for better individual
outcomes, by tailoring the training load to an individual’s response (Mann et al.
2010, Helms et al. 2018; Rauch et al. 2020). Two studies included in this review
(Riel et al. 2019; Stevens and Tan 2014), found that allowing patients to self-
select or autoregulate their training load was no less effective than following a
standardised protocol, suggesting that autoregulation may provide a method for
individually tailoring training loads to account for individual factors.
Limitations
The purpose of this systematic review was not to determine outcomes or
effectiveness of resistance training interventions in lower limb tendinopathies,
rather to report on the application of resistance training principles and adherence
of interventions. Determining the proportion of previous studies that have
implemented and reported key resistance training principles is a critical step in
advancing the knowledge and application of resistance training as treatment in
tendinopathy, as outcomes of current interventions have inadequate long-term
outcomes. While the authors believe the findings present meaningful implications
for future training interventions in tendinopathy, the review has several
limitations. The review is unable to present any meaningful estimation of the
effectiveness or dose response of resistance training on clinical outcomes such as
pain and function in lower limb tendinopathies. Although there have been previous

21
systematic reviews investigating effectiveness, conclusions are often limited and
inconclusive, due to the significant heterogeneity in methodological approaches in
resistance training interventions for tendinopathies. This includes inconsistencies
in the application and reporting of key resistance training principles and levels of
adherence to the interventions, preventing any meaningful and accurate
conclusions on outcomes. Another limitation of current RCTs on resistance training
is the lack of blinding in studies, which introduces potential bias, as evidenced in
this review. Although blinding may be difficult to implement in resistance training
interventions, blinded allocation may help minimise the potential for bias in
studies.
The importance of determining if the application of resistance training principles
impacts on improved outcomes for tendinopathy patients is an essential
requirement. As future RCTs addressing the methodological limitations identified
in this review and implementing and applying the correct scientific principles of
resistance training emerge in the literature, future systematic reviews will be in a
better position and more justified in using methods to determine true effectiveness
on clinical outcomes with meta-analysis techniques. Most studies in this review
were conducted on Achilles and patellar tendinopathy (42/52), highlighting the
paucity of resistance training studies conducted on other lower limb
tendinopathies to date, despite progressive resistance training being widely
recognised as the gold standard treatment for lower limb tendinopathies.
Therefore, the generalisability of the review findings across all lower limb
tendinopathies is limited. Further research on resistance training in other lower
limb tendinopathies is warranted, and its emergence would allow for expansion of
the resistance training recommendations highlighted in this review.
Conclusion
This review has highlighted the meaningful variability and methodological diversity
that exists across studies which have implemented resistance training
interventions as treatment for lower limb tendinopathies. Although the principles

22
of specificity and overload are adequately described and reported in resistance
training studies, there is significant methodological shortcomings when it comes
to the application and reporting of progression and individualisation principles,
along with inadequate implementation and reporting of intervention adherence.
Although the components of resistance training prescription are generally well
reported throughout studies, the extent to which the modification of load and
volume are modified to allow adequate overload and progression are poorly
reported in current studies. Many studies also fail to prescribe resistance training
within recommended scientific guidelines, with almost half of the studies adopting
a twice daily eccentric training protocol, which does not allow for basic components
of scientific training, such as recovery and progressive overload. Although many
studies have shown positive clinical outcomes of various types of resistance
training for lower limb tendinopathies, such as improved short-term pain and
function, long-term outcomes may be considered inadequate, with up to half of
patients being symptomatic at one-year follow up in several studies. This indicates
that better resistance training interventions are warranted, with improvement of
the implementation of resistance training principles, following scientific
recommendations, being a potential avenue for improving outcomes. However,
until the application of scientific resistance training principles is consistently
reached in the tendinopathy literature, proper scientific appraisal and determining
effectiveness through meta-analysis techniques cannot appropriately and
conclusively be achieved. Future research evaluating the effects of resistance
training on clinical outcomes for tendinopathies that is scientifically designed with
accurate reporting of intervention adherence is urgently warranted to better
elucidate the optimal treatment approach for this burdensome condition which has
a significant global morbidity.

23
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35
Table 3: Study characteristics
Author
Tendinopathy
Intervention
groups
Sample
size
Intervention
duration
(wks)
Outcomes +
measures
Follow-
up
length
(weeks)
Outcomes/ results
Quality
score
Beyer et al.
2015
Achilles
1. HSRT
2. ECCT
58
12
Pain (VAS),
Function
(VISA-A),
Ultrasound
52
Both interventions were effective,
with HSRT having greater patient
satisfaction at 12 but not 52 weeks.
5
Kongsgaard
et al. 2009
Patellar
1. CSI 2.
HSRT 3. ECCT
37
12
Pain (VAS),
Function
(VISA-P),
Ultrasound
26
All groups improved, with only
exercise groups maintaining
improvements at 6 months. HSRT has
good short- and long-term clinical
effects.
5
Riel et al.
2019
Plantar heel
1. fixed HSRT
2. Self-dosed
HSRT
70
12
Function
(FHSQ), Pain
(self-
efficacy),
ultrasound
12
Both groups improved pain and
function, with no significant
differences between groups.
5
Stevens &
Tan 2014
Achilles
1. fixed ECCT
2. Self-dosed
ECCT
28
6
Pain (VAS),
Function
(VISA-A)
6
Both groups improved pain and
function, with no significant
differences between groups.
5
Da Cunha et
al. 2012
Patellar
1. ECCT pain
2. ECCT no
pain
17
12
Pain (VAS),
Function
(VISA-P)
12
No difference between groups, both
groups improved pain and function.
3
Kulig et al.
2009
Posterior tibial
1. ECCT 2.
CONCT 3.
Orthoses
36
12
Pain (VAS),
function
(FFI)
12
Eccentric program was more effective
than concentric or orthoses alone.
2
Bahr et al.
2006
Patellar
1. ECCT 2.
surgery
35
12
Pain,
function
(VISA-P)
12
Both groups improved, no significant
difference between groups. Trend
favouring ECCT.
3
Lee et al.
2020
Patellar
1. ECCT 2.
ECCT + ESWT
34
12
Pain (VAS),
function
(VISA-P),
ultrasound
12
Combining exercise and ESWT could
not been shown to be more effective
than exercise alone
2
Frohm et al.
2007
Patellar
1. Standard
ECCT 2.
Overload
ECCT
20
12
Pain (VAS),
function
(VISA-P)
12
Both treatment groups improved in
the short term, with no significant
difference between groups.
4

36
Silbernagel et
al. 2001
Achilles
1. Overload
ECCT 2.
control
40
12
Pain (VAS),
function,
task
performance
52
No significant difference between
groups, at 1-year ECCT group more
satisfied with outcomes.
2
Balius et al.
2016
Achilles
1. ECCT 2.
ECCT +
supplement 3.
Supplement +
stretching
59
12
Pain (VAS),
function
(VISA-A),
ultrasound
12
Reduction in pain at rest was greater
in the groups who took the
supplement than in the ECCT alone
group
4
Mafi et al.
2001
Achilles
1. ECCT 2.
CONCT
44
12
Pain (VAS),
function
12
The results after treatment with
eccentric training was significantly
better (P<0.002) than after
concentric training.
4
Norregaard
et al. 2007
Achilles
1. ECCT 2.
Stretching
45
12
Manually
tested Pain,
function
52
Marked improvement in symptoms
and findings could be gradually
observed in both groups during the 1-
year follow-up period.
4
Stasinopolous
et al. 2004
Patellar
1. ECCT 2.
Ultrasound 3.
MT
30
4
Pain
4
ECCT was statistically significantly
better than the other two treatments
at the end of treatment.
4
De Vos et al.
2007
Achilles
1. ECCT 2.
ECCT +night
splint
70
12
Pain,
function
(VISA-A)
12
Both groups improved pain and
function, with no significant difference
between groups
5
Johannsen et
al. 2019
Plantar Heel
1. HSRT 2.
CSI 3. HSRT
+ CSI
90
12
Pain (VAS),
function
(FFI),
ultrasound
26
Combined treatment is superior both
in the short- and in the long-term.
6
MacDonald et
al. 2019
Patellar
1. ECCT 2.
ECCT + hip
exercises
41
12
Pain,
function
(VISA-P,
LEFS)
24
Favourable effects were
demonstrated with combined
treatment of eccentric squat and hip
muscle strengthening or squat only
2
Gatz et al.
2020
Achilles
1. ECCT 2.
ECCT +
isometric
42
12
Pain,
function
(VISA-A),
shear wave
elastography
12
Isometric exercises do not have
additional benefit when combined
with eccentric exercises, as assessed
over a 3-month intervention period.
3
Ganderton et
al. 2018
Gluteal
1. Ex 2. Sham
Ex
94
12
Pain,
function
(VISA-G)
52
Lack of treatment effect was found
with the addition of an exercise
program to education
5

37
Silbernagel et
al. 2007
Achilles
1. Rehab with
continued
sports 2.
Control
38
12
Pain (VAS),
function
(VISA-A)
26
Significant improvement and no
negative effects demonstrated from
continuing Achilles tendon-loading
activity, such as running and
jumping, with the use of a pain-
monitoring model, during treatment.
6
Clifford et al.
2019
Gluteal
1. isometric
Ex 2. Isotonic
Ex
30
12
Pain (NRS),
function
(VISA-G),
QoL
12
Both groups effective in reducing pain
and improving function, no difference
between groups.
2
Stergioulas et
al. 2008
Achilles
1. ECCT +
LLLT 2. ECCT
52
8
Pain (VAS),
function
(VISA-A)
12
LLLT accelerates clinical recovery
when added to ECCT
3
Rompe et al.
2008
Achilles
1. ECCT 2.
ESWT
50
12
Pain,
function
(VISA-A)
16
ESWT superior to ECCT at 16 weeks.
6
Mellor et al.
2018
Gluteal
1. Ex,
education 2.
CSI 3. control
204
8
Pain (NRS),
function
(VISA-G),
QoL (EQ5D),
GROC
52
At 52-week follow-up, education plus
exercise led to better global
improvement than corticosteroid
injection use, but no difference in
pain intensity
6
Van Ark et al.
2016
Patellar
1. isotonic Ex
2. Isometric
Ex
29
4
Pain (NRS),
function
(SLDS)
4
Both isometric and isotonic exercise
programs improved pain and function
3
Roos et al.
2004
Achilles
1. ECCT 2.
ECCT + night
splint 3. Night
splint
44
6
Pain,
function
(FAOS)
52
ECCT more effective than night splint
for improving pain and function
2
Chester et al.
2008
Achilles
1. ECCT 2.
Ultrasound
16
12
Pain (VAS),
function
(FILLA), QoL
(EQ5D)
12
There were no significant differences
between groups or clear trends over
time. Both interventions proved
acceptable with no adverse effects.
3
Rompe et al.
2007
Achilles
1. ECCT 2.
ESWT 3.
Control
75
12
Pain,
function
(VISA-A)
16
ECCT and ESWT showed comparable
positive results. The wait-and-see
strategy was ineffective.
6
Thijs et al.
2017
Patellar
1. ECCT +
ESWT 2. ECCT
52
12
Pain,
function
(VISA-P)
12
No additional effect of ESWT to EECT
for pain and function improvement.
4
Horstmann et
al. 2013
Achilles
1. ECCT 2.
Vibration
58
12
Pain (VAS),
function,
24
Pain improvements were greatest in
the eccentric group.
4

38
training 3.
control
tendon
structure
Alfredson et
al. 1998
Achilles
1. ECCT 2. CT
control
30
12
Pain (VAS)
12
Significant improvement with ECCT
2
Alvarez et al.
2006
Posterior tibial
1. Strength Ex
+ orthoses 2.
Stretching +
orthoses
39
12
Pain,
function
(FFI)
12
Both groups significantly improved in
pain and function over the 12-week
trial period. The self-report measures
showed minimal differences between
the treatment groups.
3
Kearney et
al. 2013
Achilles
1. ECCT 2.
PRP injection
20
12
Pain (VAS),
function
(VISA-A)
26
Both interventions effective, with PRP
having better outcomes, however
there was no significant difference.
5
Tumilty et al.
2012
Achilles
1. ECCT 2.
ECCT + LLLT
40
12
Pain (VAS),
function
(VISA-A)
52
There was no statistically significant
difference in VISA-A scores between
groups.
6
Yelland et al.
2011
Achilles
1. ECCT 2.
ECCT +
prolotherapy
3.
prolotherapy
43
12
Pain (VAS),
function
(VISA-A),
costs
52
prolotherapy and particularly ECCT
combined with prolotherapy give
more rapid improvements in
symptoms than ECT alone but long-
term VISA-A scores are similar.
5
McCormack
et al. 2016
Achilles
1. ECCT 2.
ECCT + MT
16
12
Pain (NPRS),
function
(VISA-A)
52
ECCT + MT more effective than ECCT
only at improving function during
both short- and long-term follow-up
3
Tumilty et al.
2016
Achilles
1. ECCT 1 2.
ECCT 1 +
LLLT 3. ECCT
2 4. ECCT 2
+LLLT
80
12
Pain,
function
(VISA-A)
12
Twice-daily exercise sessions are not
necessary as equivalent results can
be obtained with two exercise
sessions per week. The addition of
LLLT can bring added benefit.
6
Cannell et al.
2001
Patellar
1. ECCT 2.
Isotonic Ex
19
12
Pain (VAS),
return to
sport
12
Progressive drop squats
and leg extension/curl exercises both
reduced pain and enable return to
sport
3
Jonsson et al.
2005
Patellar
1. ECCT 2,
CONCT
19
12
Pain (VAS),
function,
(VISA-P)
12
eccentric, but not concentric,
quadriceps training on a decline
board, seems to reduce pain in PT
1
Kedia et al.
2014
Achilles
1. CT 2. ECCT
+ CT
36
12
Pain (VAS),
function
(SF36)
12
No significant differences between
groups. CT and ECCT both effective.
5

39
Herrington et
al. 2007
Achilles
1. ECCT + CT
2. CT
25
12
Pain,
function
(VISA-A)
12
ECCT + CT was more effective than
CT alone for pain and function.
4
Houck et al.
2015
Posterior tibial
1. Orthosis +
stretching 2.
+ strength Ex
39
12
Pain,
function
(FFI)
12
Both groups significantly improved in
pain and function over the 12-week
trial period. minimal differences
between the treatment groups.
5
Dimitrios et
al. 2012
Patellar
1. ECCT 2.
ECCT +
stretching
43
4
Pain,
function
(VISA-P)
24
ECCT and static stretching exercises
is superior to ECCT alone to reduce
pain and improve function
3
Petersen et
al. 2007
Achilles
1. ECCT 2.
Brace 3. ECCT
+ brace
100
12
Pain (VAS),
function
(AOFAS),
QoL (SF-36)
54
The VAS score for pain, AOFAS score,
and SF-36 improved significantly in
all 3 groups at all 3 follow-ups, no
significant difference between groups
3
Steunebrink
et al. 2013
Patellar
1. ECCT +
GTN 2. ECCT
33
12
Pain,
function
(VISA-P)
24
GTN + ECCT does not improve clinical
outcome compared to placebo
patches + ECCT
5
Rompe et al.
2009
Achilles
1. ECCT +
ESWT 2. ECCT
68
12
Pain,
function
(VISA-A)
52
Combined ECCT + ESWT more
effective at 4 months follow-up
5
Young et al.
2005
Patellar
1. ECCT step
2. ECCT
decline
17
12
Pain (VAS),
function
(VISA-P)
52
Both groups improved pain and
sporting function at 12 months.
Decline squat more effective.
3
De Jonge et
al. 2010
Achilles
1. ECCT 2.
ECCT + night
splint
58
12
Pain,
function
(VISA-A)
52
ECCT with or without a night splint
improved functional outcome at 1-
year. no significant difference in
clinical outcome between groups.
5
Praet et al.
2019
Achilles
1. ECCT +
collagen
peptides
20
26
Pain,
function
(VISA-A)
26
Oral supplementation of collagen
peptides may accelerate the clinical
benefits of ECCT.
5
Rathleff et al.
2015
Plantar heel
1. HSRT 2.
stretching
48
12
Pain,
function
(FFI)
52
HSRT superior to plantar fascia
stretching for pain and function
3
Knobloch et
al. 2008
Achilles
1. ECCT +
brace 2. ECCT
116
12
Pain (VAS),
function
(FAOS)
12
No additional effect of heel brace to
ECCT alone.
4
Wheeler et
al. 2017
Plantar heel
1. General Ex
2. Ex + night
splint
40
12
Pain (VAS),
Function
(FFI, FAAM)
12
Improvement in both groups, with no
significant differences between
groups.
5

40
Table 4: Application of resistance training principles
Author
Spec
ificity
Over
load
Progression
+ method
Individualised
+ method
Frequency
(d/wk)
Intensity
Time
(min)
Sets
Reps
Exercise
mode/type
Adherence
RTP,
Total
score
/10
Beyer et al.
2015
Y
Y
Y, increase
resistance/
load
Y, pain
response 4-
5/10
3
15RM –
6RM
107 x
wk
(HSRT)
308 x
wk
(ECCT)
3-4
15-6
Heel raises, with
external weights
Y, diary
7, 9
Kongsgaard
et al. 2009
Y
Y
Y, increase
resistance
NR
3
15RM –
6RM
NR
3-4
15-6
DSL squats, squat,
leg press, hack
squat, with
external weights
NR
5, 5
Riel et al.
2019
Y
Y
Y, increase
resistance
or volume
Y, as many
sets as
possible
3
8RM –
12RM
tut
3-5,
AMAP
8-12
Heel raises, loaded
backpack
Y, diary,
20 not
returned
7, 9
Stevens &
Tan 2014
Y
Y
Y, increase
resistance
or volume
Y, as many
reps as
possible
7, 2xd
15RM
NR
2 x 6
(12)
15
(180
total)
Heel raises
(straight leg &
bent knee), loaded
backpack
Y, diary
7, 9
Da Cunha et
al. 2012
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response
3
15RM
NR
3
15
Eccentric decline
squat
NR
8, 8
Kulig et al.
2009
Y
Y
Y, increase
resistance
(0.9kg
conforce
spring)
Y, increase
isokinetic
resistance as
able
7, 2xd
15RM
NR
2 x 3
(6)
15
(180)
Isokinetic resisted
horizontal
adduction with
plantar flexion
Y, diary,
68% (39-
98)
8, 10
Bahr et al.
2006
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response less
3/10,
increase 5kg
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
DSL squat, loaded
backpack
NR
8, 8
Lee et al.
2020
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response
7, 2Xd
15RM
NR
2 X 3
(6)
15
(180)
DSL squat, loaded
backpack
Y, diary
8, 10

41
4/10,
increase 5kg
Frohm et al.
2007
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response
5/10,
increase 5kg
1.2 2. 7,
2xd
15-16RM
70
mins x
session
3-4
15-
16
1. The Bromsman
eccentric overload
training device 2.
DSL squat, loaded
backpack
NR
8,8
Silbernagel et
al. 2001
Y
Y
Y, increase
resistance,
volume,
speed &
difficultly
Y, pain
response
5/10
7
5-15RM
NR
3
5-15
Double and single
leg Slow Heel
raises, fast
rebounding heel
raises
Y, diary
7, 9
Balius et al.
2016
Y
UC
UC
UC
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
Alfredson heel
raises, straight &
bent knee
PT
recorded;
70%
minimum
allowed
2, 4
Mafi et al.
2001
Y
Y
Y, increase
resistance
Y, pain
response
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
Alfredson heel
raises, straight &
bent knee, loaded
with backpack or
weight machines
NR
7, 7
Norregaard
et al. 2007
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response,
increase 5kg
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
Alfredson heel
raises, straight &
bent knee, loaded
with backpack
Y. diary,
results NR
8, 9
Stasinopolous
et al. 2004
Y
Y
Y, increase
resistance
Y, pain
response
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
DSL squat,
handheld external
weights
NR
8, 8
De Vos et al.
2007
Y
Y
Y, increase
resistance
Y, pain
response
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
Alfredson heel
raises, straight &
bent knee, loaded
with backpack or
weight machines
Y, diary
7, 9
Johannsen et
al. 2019
Y
UC
UC
NR
3
NR
NR
NR
NR
(1) heel-rises, (2)
flexion of the first
toe against elastic
band. (3)
Inversion of the
NR
2, 2

42
foot against elastic
band
MacDonald et
al. 2019
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response
5/10,
increase 5kg,
correct
technique
7, 2xd
15RM
NR
2 X 3
(6)
15
(180)
DSL squat
eccentric protocol
with addition of
isotonic hip
exercise, loaded
backpack
Y, diary,
42.5% full
8, 10
Gatz et al.
2020
Y
Y
Y, increase
resistance
Y, pain
response
7, 2 X D
15RM
NR
2 X 3
(6)
15
(180)
Alfredson eccentric
heel raise protocol
+ isometric
exercise
Y, verbal,
NR
7, 8
Ganderton et
al. 2018
Y
Y
Y, increase
difficulty
Y, individual
ability
determined
progression
7, 2 x d
5-15RM
30MIN
X D
2-4
5-15
isometric loading
of gluteals, and
kinetic chain
strength exercises
Y, diary
6, 8
Silbernagel et
al. 2007
Y
Y
Y, Increase
resistance,
volume and
speed of
exercises
Y, Increased
resistance,
volume and
speed guided
by Pain
response
7
10-20RM
NR
3
10-
20
2-legged, 1-
legged, eccentric,
and fast
rebounding toe
raises, plyometric
exercise. Loaded
with backpack or
weight machine
Y, diary
7, 9
Clifford et al.
2019
Y
Y
Y, increase
resistance
band
strength
Y, pain
response
5/10
7
6-10RM
6min
TUT x
d
3-6
6-10
Isotonic &
isometric hip
abduction, loaded
with bands
Y, diary
7, 9
Stergioulas et
al. 2008
Y
Y
Y, increase
resistance
(4kg inc)
Y, pain
response
5/10
4
12RM
NR
12
12
Eccentric heel
raise, knee
straight & flexed,
loaded backpack
Y, NR
8, 9
Rompe et al.
2008
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response,
increase 5kg
7, 2 X D
10-15RM
NR
3 X 2
(6)
10-
15
(180)
Alfredson eccentric
heel raise, knee
straight & flexed,
loaded backpack
Y, verbal,
NR
8, 9
Van Ark et al.
2016
Y
Y
Y, increase
resistance
2.5% per
week
Y, pain
response,
correct
technique,
4
isometric
(80%
1RM)
isotonic
NR
4-5
5-8
Leg extension
machine, external
weight. Audio used
for speed tempo
NR
8, 8

43
2.5%
increase
(80%
8RM)
Roos et al.
2004
Y
Y
Y, increase
resistance
Y, pain
response
7, 2 X D
15RM
NR
1-3
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
7, 7
Chester et al.
2008
Y
Y
Y, increase
resistance
Y, pain
response
7
15RM
NR
3 X 2
(6)
15
(90)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
7, 7
Rompe et al.
2007
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response,
increase 5kg
7, 2 X D
10-15RM
NR
3 X 2
(6)
10-
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
8, 8
Thijs et al.
2017
Y
Y
Y, increase
resistance
Y, pain
response,
4/10
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
DSL eccentric
squat, loaded
backpack
NR
7, 7
Horstmann et
al. 2013
Y
Y
Y, increase
resistance
+ volume,
based on
fatigue
Y, increase
resistance +
volume,
based on
fatigue
7
15RM
NR
3-4
15
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
7, 7
Alfredson et
al. 1998
Y
Y
Y, increase
resistance
Y, pain
response
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
or weight machine
NR
7, 7
Alvarez et al.
2006
Y
Y
Y, increase
resistance
(elastic
bands) and
volume
Y, increase
resistance
based on
pain
response +
correct
technique
7, 2 X D
30RM
NR
3
30
Isotonic exercise
with elastic bands,
increased
resistance (elastic
bands strength) 1.
Bilateral heel
raises 2. Ankle
plantar flexion with
adduction and
Y, diary
7, 9

44
Inversion.
3. Unilateral heel
raises (standing)
Kearney et
al. 2013
Y
Y
Y, progress
from DL to
SL with
increased
resistance
Y, pain
response,
progress
from DL to
SL with
increased
load
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack,
DL progressing to
SL
NR
7, 7
Tumilty et al.
2012
Y
Y
Y, increase
resistance
Y, pain
response
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
7, 7
Yelland et al.
2011
Y
Y
Y, increase
resistance
Y, pain
response
4/10
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
Y, diary
7, 9
McCormack
et al. 2016
Y
Y
Y, increase
resistance
NR
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
5, 5
Tumilty et al.
2016
Y
Y
Y, increase
resistance
Y, pain
response,
4/10
2
15RM
NR
3 X 2
(180)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack.
2Xwk V D
Y, diary,
46
returned
7, 9
Cannell et al.
2001
Y
Y
Y, increase
resistance
with fixed
loading
protocol &
external
weight
Y, pain
response
5
10-20RM
NR
3
10-
20
Progressive drop
squats and leg
extension/curl
exercises, fixed
loading protocol,
external weights
NR
8, 8
Jonsson et al.
2005
Y
Y
Y, increase
resistance
Y, self-
acceptable
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
Eccentric v
concentric DSL
NR
7, 7

45
pain
response
squat, loaded
backpack
Mellor et al.
2018
Y
Y
Y, increase
diffciculty/
intensity
(BORG)
Y, pain
response
5/10, BORG
scale (13-17
target)
7
BORG
(13-17)
30 min
x
session
1-2
3-15
Comprehensive
progressive
exercise program
targeting hip
muscles,
monitored by pain
response and
BORG scale.
External load NR.
Spring resistance
for hip abduction
Y, diary,
80%
8, 10
Kedia et al.
2014
Y
Y
Y, increase
resistance
Y, exercise
difficultly,
increase
resistance
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
Y, diary,
NR
7, 8
Herrington et
al. 2007
Y
Y
Y, increase
speed and
resistance
Y, increase
speed and
resistance
based on
pain
response
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
Y, diary,
NR
7, 8
Houck et al.
2015
Y
Y
Y, increase
resistance
– elastic
bands
strength
Y, increase
resistance
based on
pain
response &
Ex technique
7, 2 X D
30RM
30 min
x
session
3 X 2
(6)
30 X
3 X 3
(180)
Bilateral &
unilateral heel
raises, ankle
plantarflexion with
adduction &
inversion.
Resistance bands
Y, diary
7, 9
Dimitrios et
al. 2012
Y
Y
Y, increase
resistance
with
handheld
weights
Y, pain
response
5
15RM
NR
3
15
Eccentric DSL
squat, handheld
weights
Y, diary,
NR
7, 8
Petersen et
al. 2007
Y
Y
Y, increase
resistance
Y, pain
response
7, 3 x D
15RM
NR
3 X 3
(9)
15
(270)
Modified Alfredson
eccentric heel
raise, knee
Y, diary,
NR
7, 8

46
straight & flexed,
loaded backpack
Steunebrink
et al. 2013
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response,
3/10 =
increase load
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
- Eccentric DSL
squat
NR
8, 8
Rompe et al.
2009
Y
Y
Y, increase
resistance
(5kg inc)
Y, pain
response
7, 2 X D
15RM
NR
3 X 2
(6)
10-
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
NR
8, 8
Young et al.
2005
Y
Y
Y, increase
speed, then
resistance
(5kg inc)
Y, pain
response
7. 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
DSL squat, loaded
backpack
Y, diary
8, 10
De Jonge et
al. 2010
Y
Y
Y, increase
resistance
Y, pain
response
7, 2 x d
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
or weight machine
Y, diary
7, 9
Praet et al.
2019
Y
Y
Y, increase
speed, then
resistance
(5kg inc
until max
60kg)
Y, pain
response
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
loaded backpack
Y, diary,
NR
8, 9
Rathleff et al.
2015
Y
Y
Y, increase
resistance
NR
3
12-8RM
NR
3-5
12-8
Heel raise on step
with toes
maximally
dorsiflexed on
towel
NR
5, 5
Knobloch et
al. 2008
Y
NR
NR
NR
7, 2 X D
15RM
NR
3 X 2
(6)
15
(180)
Modified Alfredson
eccentric heel
raise, knee
straight & flexed,
NR
2, 2
Wheeler et
al. 2017
Y
NR
NR
NR
NR
NR
NR
NR
NR
stretching, calf &
foot muscle
strengthening and
balance exercises.
NR
2, 2

47