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Achilles and Patellar Tendinopathy Loading Programmes: A Systematic Review Comparing Clinical Outcomes and Identifying Potential Mechanisms for Effectiveness

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Introduction Achilles and patellar tendinopathy are overuse injuries that are common among athletes. Isolated eccentric muscle training has become the dominant conservative management strategy for Achilles and patellar tendinopathy but, in some cases, up to 45 % of patients may not respond. Eccentric-concentric progressing to eccentric (Silbernagel combined) and eccentric-concentric isotonic (heavy-slow resistance; HSR) loading have also been investigated. In order for clinicians to make informed decisions, they need to be aware of the loading options and comparative evidence. The mechanisms of loading also need to be elucidated in order to focus treatment to patient deficits and refine loading programmes in future studies. Objectives The objectives of this review are to evaluate the evidence in studies that compare two or more loading programmes in Achilles and patellar tendinopathy, and to review the non-clinical outcomes (potential mechanisms), such as improved imaging outcomes, associated with clinical outcomes. Methods Comprehensive searching (MEDLINE, EMBASE, CINAHL, Current Contents and SPORTDiscus™) identified 403 studies. Two authors independently reviewed studies for inclusion and quality. The final yield included 32 studies; ten compared loading programmes and 28 investigated at least one potential mechanism (six studies compared loading programmes and investigated potential mechanisms). Results This review has identified limited (Achilles) and conflicting (patellar) evidence that clinical outcomes are superior with eccentric loading compared with other loading programmes, questioning the currently entrenched clinical approach to these injuries. There is equivalent evidence for Silbernagel combined (Achilles) and greater evidence for HSR loading (patellar). The only potential mechanism that was consistently associated with improved clinical outcomes in both Achilles and patellar tendon rehabilitation was improved neuromuscular performance (e.g. torque, work, endurance), and Silbernagel-combined (Achilles) HSR loading (patellar) had an equivalent or higher level of evidence than isolated eccentric loading. In the Achilles tendon, a majority of studies did not find an association between improved imaging (e.g. reduced anteroposterior diameter, proportion of tendons with Doppler signal) and clinical outcomes, including all high-quality studies. In contrast, HSR loading in the patellar tendon was associated with reduced Doppler area and anteroposterior diameter, as well as greater evidence of collagen turnover, and this was not seen following eccentric loading. HSR seems more likely to lead to tendon adaptation and warrants further investigation. Improved jump performance was associated with Achilles but not patellar tendon clinical outcomes. The mechanisms associated with clinical benefit may vary between loading interventions and tendons. Conclusion There is little clinical or mechanistic evidence for isolating the eccentric component, although it should be made clear that there is a paucity of good quality evidence and several potential mechanisms have not been investigated, such as neural adaptation and central nervous system changes (e.g. cortical reorganization). Clinicians should consider eccentric-concentric loading alongside or instead of eccentric loading in Achilles and patellar tendinopathy. Good-quality studies comparing loading programmes and evaluating clinical and mechanistic outcomes are needed in both Achilles and patellar tendinopathy rehabilitation.
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SYSTEMATIC REVIEW
Achilles and Patellar Tendinopathy Loading Programmes
A Systematic Review Comparing Clinical Outcomes and Identifying Potential
Mechanisms for Effectiveness
Peter Malliaras Christian J. Barton
Neil D. Reeves Henning Langberg
!Springer International Publishing Switzerland 2013
Abstract
Introduction Achilles and patellar tendinopathy are
overuse injuries that are common among athletes. Isolated
eccentric muscle training has become the dominant con-
servative management strategy for Achilles and patellar
tendinopathy but, in some cases, up to 45 % of patients
may not respond. Eccentric-concentric progressing to
eccentric (Silbernagel combined) and eccentric-concentric
isotonic (heavy-slow resistance; HSR) loading have also
been investigated. In order for clinicians to make informed
decisions, they need to be aware of the loading options and
comparative evidence. The mechanisms of loading also
need to be elucidated in order to focus treatment to patient
deficits and refine loading programmes in future studies.
Objectives The objectives of this review are to evaluate
the evidence in studies that compare two or more loading
programmes in Achilles and patellar tendinopathy, and to
review the non-clinical outcomes (potential mechanisms),
such as improved imaging outcomes, associated with
clinical outcomes.
Methods Comprehensive searching (MEDLINE, EM-
BASE, CINAHL, Current Contents and SPORTDiscus
TM
)
identified 403 studies. Two authors independently
reviewed studies for inclusion and quality. The final yield
included 32 studies; ten compared loading programmes and
28 investigated at least one potential mechanism (six
studies compared loading programmes and investigated
potential mechanisms).
Results This review has identified limited (Achilles) and
conflicting (patellar) evidence that clinical outcomes are
superior with eccentric loading compared with other
loading programmes, questioning the currently entrenched
clinical approach to these injuries. There is equivalent
evidence for Silbernagel combined (Achilles) and greater
evidence for HSR loading (patellar). The only potential
mechanism that was consistently associated with improved
clinical outcomes in both Achilles and patellar tendon
rehabilitation was improved neuromuscular performance
(e.g. torque, work, endurance), and Silbernagel-combined
(Achilles) HSR loading (patellar) had an equivalent or
higher level of evidence than isolated eccentric loading. In
the Achilles tendon, a majority of studies did not find an
association between improved imaging (e.g. reduced
anteroposterior diameter, proportion of tendons with
Doppler signal) and clinical outcomes, including all high-
quality studies. In contrast, HSR loading in the patellar
tendon was associated with reduced Doppler area and
anteroposterior diameter, as well as greater evidence of
collagen turnover, and this was not seen following eccen-
tric loading. HSR seems more likely to lead to tendon
adaptation and warrants further investigation. Improved
jump performance was associated with Achilles but not
patellar tendon clinical outcomes. The mechanisms asso-
ciated with clinical benefit may vary between loading
interventions and tendons.
Electronic supplementary material The online version of this
article (doi:10.1007/s40279-013-0019-z) contains supplementary
material, which is available to authorized users.
P. Malliaras (&)!C. J. Barton
Centre for Sports and Exercise Medicine, Mile End Hospital,
Queen Mary, University of London, London, UK
e-mail: p.malliaras@qmul.ac.uk
N. D. Reeves
Institute for Biomedical Research into Human Movement
and Health, Manchester Metropolitan University,
Manchester, UK
H. Langberg
Institute of Sports Medicine, Bispebjerg Hospital,
Copenhagen, Denmark
Sports Med
DOI 10.1007/s40279-013-0019-z
Conclusion There is little clinical or mechanistic evi-
dence for isolating the eccentric component, although it
should be made clear that there is a paucity of good quality
evidence and several potential mechanisms have not been
investigated, such as neural adaptation and central nervous
system changes (e.g. cortical reorganization). Clinicians
should consider eccentric-concentric loading alongside or
instead of eccentric loading in Achilles and patellar ten-
dinopathy. Good-quality studies comparing loading pro-
grammes and evaluating clinical and mechanistic outcomes
are needed in both Achilles and patellar tendinopathy
rehabilitation.
1 Introduction
Achilles and patellar tendinopathy are overuse injuries
characterized by localized tendon pain with loading and
dysfunction. Both are common among athletes and Achil-
les tendinopathy may also affect sedentary people. Achilles
and patellar tendinopathy is the focus of this review
because these are the two major locomotor tendons affec-
ted by tendinopathy. Injury to these tendons can severely
impact upon recreational and everyday activities. Patho-
logical features include altered cellularity (increased or
decreased), break down in the extracellular matrix (ground
substance accumulation, disorganized collagen, neurovas-
cular ingrowth) [1,2]. Endocrine tenocytes and nerve
endings release biochemicals that are thought to have a role
in tendon pain (e.g. substance P) [3,4]. Both extrinsic (e.g.
overuse) and intrinsic factors (e.g. lipid levels, genes) may
predispose to injury, but pathoaetiology is poorly under-
stood [5].
Eccentric muscle loading has become the dominant
conservative intervention strategy for Achilles and patellar
tendinopathy over the last decade. Eccentric loading
involves isolated, slow-lengthening muscle contractions.
Other contraction types have been investigated, including
eccentric-concentric and isolated concentric, and, in some
studies, they have been compared with eccentric loading.
Previous systematic reviews have evaluated the evidence
for eccentric muscle loading in Achilles [610] and patellar
[11,12] tendinopathy, concluding that outcomes are
promising but high-quality evidence is lacking. The first
aim of this review is to synthesis evidence from studies
comparing two or more loading programmes in Achilles
and patellar tendinopathy. The findings of this review will
guide clinical decisions and identify areas for further
research.
It is clear from the eccentric loading evidence that not
all patients respond to this intervention. In one study, 45 %
of patients were considered to have failed treatment (a less
than 10-point improvement in the Achilles version of the
Victorian Institute of Sports Assessment [VISA-A] score)
[13]. This clearly indicates eccentric loading may not be
effective for all patients with tendinopathy. Understanding
the mechanisms of loading interventions in tendinopathy,
and which mechanisms are associated with improved
clinical outcomes, may improve rehabilitation outcomes.
Loading programmes can then be targeted to patient defi-
cits (e.g. neuromuscular deficits) and mechanisms associ-
ated with clinical outcomes can be maximized (e.g. load
intensity to maximize muscle and tendon adaptation),
potentially improving clinical outcomes. The second aim is
to investigate the non-clinical outcomes (potential mecha-
nisms), such as improved strength and imaging pathology,
associated with improved clinical outcomes following
Achilles and patellar tendinopathy rehabilitation.
2 Methods
A systematic review was undertaken following the protocol
guidelines outlined in the PRISMA statement [14].
2.1 Search Criteria
A search of MEDLINE, EMBASE, CINAHL, Current
Contents and SPORTDiscus
TM
electronic databases was
undertaken from inception to June 2012. Search terms
relating to exercise (‘eccentric’, ‘rehabilitation’, ‘resistance
training’, ‘exercise therapy’), pathology (‘tendinopathy’,
‘tendinitis’, etc.) and the site (‘Achilles’, ‘patellar’) were
combined in the final search (Table 1shows the MEDLINE
example). Each search term was mapped to specific MeSH
subject headings within each database. The reference lists
of eccentric loading systematic reviews and the studies in
the final yield were manually checked to identify other
studies.
2.2 Selection Criteria
Studies investigating clinical outcomes of loading pro-
grammes in Achilles and patellar tendinopathy were
included. This comprised any type of muscle-tendon unit
loading, including eccentric, concentric, combined eccen-
tric-concentric, isometric and stretch-shortening cycle
(SSC), loading involving a fast muscle tendon unit
eccentric-concentric turnaround (e.g. jumping, hopping).
Human studies with a minimum follow-up period of
4 weeks and single cohort studies and trials comparing two
or more groups were included. From this, broad yield
studies that compared two or more loading programmes in
Achilles and patellar tendinopathy formed a subgroup. This
included randomized controlled trials (RCTs) and con-
trolled clinical trials (CCTs) that were not randomized.
P. Malliaras et al.
Stretching alone was not considered a loading programme,
but studies that compared loading with and without con-
tinued sport were included. Single cohort studies and trials
that investigated one or more non-clinical or mechanistic
outcome (e.g. imaging and muscle performance measures
such as peak torque) were included in another subgroup.
Studies that did not include any participants with ten-
dinopathy were excluded, as were studies if they investi-
gated loading following another primary intervention, such
as injections or surgery. Other exclusion criteria included
non-English studies, abstracts, non-peer-reviewed studies,
case reports and reviews.
2.3 Review Process
Two reviewers (PM, CB) independently reviewed the title
and abstract of all retrieved studies and those satisfying the
inclusion and exclusion criteria were included in the final
yield. If there was insufficient information in the title and
abstract, the full text was obtained for adequate evaluation.
Disagreement between the two authors was resolved by
consensus.
2.4 Quality Assessment
A modified version [15] of a scale developed to assess the
quality of intervention studies in patellofemoral joint pain
syndrome [16] was used to evaluate study quality. Four
quality components were evaluated (participants, inter-
ventions, outcome measures, and data presentation and
analysis), each scored a maximum of 10 points (40 points
in total) and contained three to four items. The item
relating to the control and placebo group was modified to
relate to the control group only because placebo is not
practical with exercise interventions. The item was scored
out of 4, with 2 points for comparison to another exercise
intervention and 4 points for adequate control (i.e. a wait-
and-see group or equivalent comparison group minus the
exercise intervention). The adequate numbers item was
scored out of 2 rather than 4 and the group homogeneity
item was scored out of 4 rather than 2 and modified to
pertain to adequate description and homogeneity of key
group characteristics (age, gender, activity, severity). Case
series studies could score a maximum of 34 points (the
control group and randomization items were excluded).
Two reviewers independently assessed the quality of
included studies and disagreement was resolved by con-
sensus. Studies scoring greater than 70 % on the quality
assessment were considered high quality.
2.5 Data Extraction and Analysis
Key data relating to sample demographics, interventions
and outcomes were extracted from each study. This
included study design (e.g. an RCT), groups/description of
loading and sample sizes, participant demographics (age,
gender, activity level) and clinical and mechanistic out-
comes. Only data from loading interventions were extrac-
ted. Given the heterogeneity in interventions and outcome
measures a qualitative data synthesis was performed.
Definitions for ‘levels of evidence’ were guided by rec-
ommendations made by van Tulder et al. [17] and are
shown in Table 2.
3 Results
Figure 1shows the process of identifying studies. There
were 403 studies in the initial yield after removing dupli-
cates. Ninety-two studies were assessed in full text, and a
further 60 studies were excluded, leaving a yield of 33
studies either comparing two loading programmes or eval-
uating at least one non-clinical outcome (potential mecha-
nism). In the final yield there were ten studies comparing
loading programmes and 29 studies investigating at least one
potential mechanism (six studies compared loading pro-
grammes and investigated potential mechanisms).
The quality assessment of all studies in this systematic
review is shown in the table in the Online Resource [Online
Resource 1]. The mean quality score was 54 % and the
range was from 26 % to 83 %. Only seven (21 %) studies
achieved a high-quality rating [11,1823]. Five (15 %)
Table 1 Search terms in MEDLINE database
Search term
1 ‘eccentric’, ‘concentric’, ‘isometric’, ‘training’, ‘exercise’ (title & abstract) ‘Exercise Therapy’, ‘Exercise’, ‘Rehabilitation’, ‘Resistance
training’ (MeSH)
AND
2 ‘achilles tendon’, ‘achilles’, ‘tendoachilles’, ‘tendo-achilles’, ‘triceps-surae’, ‘patellar tendon’, ‘patellar ligament’ (title & abstract) ‘Achilles
Tendon’, ‘Patellar Ligament’ (MeSH)
AND
3 ‘tendinopathy’, ‘tendinitis’, ‘tendinosis’, ‘partial rupture’, ‘paratenonitis’, ‘peritendinitis’, ‘Achillodynia’ (title & abstract) ‘Tendinopathy’,
‘Tendon Injuries’ (MeSH)
Loading of Achilles and Patellar Tendinopathy
studies had a quality score below 40 % [2428] and find-
ings from these studies were not included in the recom-
mended levels of evidence. Eleven (55 %) trials were
adequately randomized [11,18,19,2123,2933]. Three
studies did not randomize participants into groups [27,34,
35], and the remaining studies did not adequately describe
the randomization process [26,28,3639]. Only seven
studies (21 %) reported adequate blinding of outcome
assessors [1923,29,38], so experimenter bias may have
influenced the findings in a majority of studies. Only two
studies (6 %) adequately reported inclusion and exclusion
criteria [18,36]. In many studies, tendon pain with loading
was not clear as an inclusion criterion and previous surgery
or other injuries were not explicitly excluded. Forty-two
percent (14 of 33) used adequate outcome measures [11,
1923,30,31,36,3943]. This was usually a pain outcome
that was not validated, such as a visual analogue scale
(VAS) or an absence of functional outcomes. Only 12
(36 %) studies used the VISA-A or patellar tendon version
of the VISA questionnaire, which is a disease-specific and
validated pain and functional outcome measure (0–100
points, 100 =no pain and full function). Most studies
described the loading interventions partially, with the mean
score for that item being 2.8 of 4 (63 %). Few studies
described the speed of each contraction [28,44] and
maximum load [11,19,29,45]. A key issue with this
literature is that the severity and irritability of tendons is
generally not reported, so tendons may be at very different
places along the reactive-degenerative symptomatic spec-
trum, and this will influence the response to load [46].
3.1 Description of Clinical Loading Programmes
Twenty-three Achilles [2125,28,30,3235,3742,44,
45,4749,51] and 11 patellar tendon studies [11,1820,
26,27,29,31,36,43,47] were included in this review (one
study included both Achilles and patellar tendon cohorts
[47]). A majority of studies in the Achilles (16 of 23, 70 %)
and patellar tendon (6 of 10, 60 %) investigated the iso-
lated eccentric loading programme popularized by Al-
fredson [35] in at least one group. One Achilles [37] (4 %)
and two patellar tendon studies [29,31] (20 %) used the
eccentric-concentric Stanish and Curwin model [50]. Some
studies have described this programme as ‘eccentric’ when
it actually involves both concentric and eccentric contrac-
tion [37,50]. In the Achilles studies, four [23,30,40,41]
(17 %) investigated the combined Silbernagel programme
[30] involving progression from eccentric-concentric to
eccentric load and, finally, faster eccentric-concentric and
plyometric loading. Two patellar tendon studies [19,20]
(20 %) investigated heavy-slow resistance (HSR) loading
that involves slow double leg isotonic eccentric-concentric
contractions. Table 3shows the characteristics of the four
main loading programmes used in Achilles and patellar
tendinopathy rehabilitation. Few studies included groups
undertaking isotonic loading [29,37], isokinetic loading
[26,47], concentric [32,36] and flywheel loading [43].
3.2 Comparison of Loading Programmes in Achilles
and Patellar Tendinopathy
Ten studies compared loading programmes in either
Achilles [23,30,32,37] or patellar tendinopathy [11,19,
27,29,31,36]. This included nine RCTs and one CCT. The
mean quality score of studies comparing loading pro-
grammes was 57 % (range 34–83 %). Only two studies
[19,23] (20 %) had a high-quality score ([70 %) and one
Table 2 Grading the recommendations for comparing loading
programmes
Evidence
grade
Recommendation
Strong Consistent findings among n C2 high-quality studies
Moderate Consistent findings amongst multiple low-quality
studies, or one high-quality study
Limited Findings from one low-quality study.
Conflicting Inconsistent findings among multiple studies
None No studies found
398 papers
identified after
removing duplicates
403 papers identified
92 retrieved in full text
32 studies compared two
loading programmes or
investigated at least one
potential mechanism
311 excluded based on abstract
16 animal studies
7 cruciate ligament repair
83 opinion pieces, abstracts, case
studies, reviews
113 post-surgery, rupture, other
treatment
79 no-exercise intervention
3 <4 weeks’ intervention
10 not Achilles or patellar tendon
2 non-English
60 excluded based on full text
2 animal studies
8 among ‘normal’ participants
6 opinion pieces, abstracts, case
studies, reviews
16 post-surgery, rupture, other
treatment
3 no-exercise intervention
1 <4 weeks’ intervention
2 non-English
22 do not compare loading
programmes or investigate
mechanisms
10 compared
loading programmes
28 investigated
mechanisms
5 identified via hand
search, reference
check
Fig. 1 Study selection flow diagram (six studies compared loading
programmes and investigated potential mechanisms)
P. Malliaras et al.
other study scored just below the cut off for a high-quality
rating (68 %) [31].
Data extracted from each study comparing loading
programmes and investigating mechanisms are shown in
Table 4. There were 139 participants with a mean age of
44 years in the four studies comparing loading programmes
in Achilles tendinopathy, with slightly more men than
women (61 %), and the proportion participating in sport
ranged from 57 % to 100 %.
There is limited evidence from three low-quality studies,
which showed that (i) a greater proportion of patients are
satisfied and return to a preinjury level of activity following
eccentric, compared with concentric, loading [32]; (ii)
VAS pain outcomes and patient satisfaction are greater
following Silbernagel-combined loading compared with
calf raises and stretching [30]; and (iii) VAS pain and
return-to-sport outcomes were greater following Stanish
and Curwin, compared with isotonic loading [37]. In one
high-quality study there was moderate evidence, which
showed that VISA-A improvement following Silbernagel-
combined loading is similar whether sport is continued or
not [23].
There were six patellar tendon studies including 112
participants with a mean age of 27 years. All participants
were active in sports and greater than three-quarters were
men (77 %). There is moderate evidence from two high-
quality studies, which showed that (i) VISA improvement
is comparable but patient satisfaction is greater following
HSR versus eccentric loading [19]; (ii) there is no differ-
ence in change in VISA scores during a volleyball season
with and without the addition of eccentric loading [11].
There is limited evidence from three low-quality studies,
which showed that (i) clinical outcomes are superior fol-
lowing eccentric, compared with Stanish and Curwin
loading [31] and concentric loading [36]; (ii) VAS pain and
return-to-sport outcomes are superior following Stanish
and Curwin, compared with isotonic loading [29]. In one
very low-quality study, clinical outcomes were superior
following eccentric compared with eccentric loading
without a decline board [27].
3.3 Potential Mechanisms of Achilles and Patellar
Tendinopathy Loading Programmes
Twenty-nine studies investigated non-clinical potential
mechanisms of loading programmes in Achilles [2125,28,
30,3335,3742,44,45,48,49,51] and patellar tendin-
opathy [11,1820,26,29,43,47]. This included 14 RCTs,
two CCT’s and 13 single cohort studies. Studies investi-
gating mechanisms had a mean quality score of 54 % (range
26–79 %) and seven studies (25 %) had a high-quality
rating [11,1822,42]. There were 293 participants with
Achilles tendinopathy in 21 studies. They had a mean age of
47 years, 79 % were active in sport and 59 % were men.
One-hundred and sixty-three participants with patellar
tendinopathy were investigated in eight studies. They had a
mean age of 28 years, the majority were men (81 %) and
almost all were active in sport (98 %).
3.3.1 Achilles
3.3.1.1 Neuromuscular and Jump Performance Outcomes
3.3.1.1.1 Eccentric Loading. There is limited evidence
from one low-quality study that improved clinical out-
comes are associated with increased ankle planterflexion
torque [35]. There is moderate evidence from three low-
quality studies, which show that (i) improved clinical
outcomes are associated with increased calf work [35,38]
(ii) resolution in side-to-side ankle planterflexor work and
torque deficits [34,35].
3.3.1.1.2 Silbernagel-Combined Loading. There is lim-
ited evidence from one low-quality study, which showed
that (i) improved clinical outcomes are associated with
increased planterflexor endurance [30], (ii) improvement in
Table 3 Characteristics of Alfredson, Stanish and Curwin, Silbernagel and HSR programmes
Programmes Type of exercise Sets, reps Frequency Progression Pain
Alfredson Eccentric 3, 15 Twice daily Load Enough load to achieve up
to moderate pain
Stanish and Curwin Eccentric-concentric, power 3, 10–20 Daily Speed then load Enough load to be painful
in third set
Silbernagel Eccentric-concentric, eccentric, faster
eccentric-concentric, balance
exercise [30,41], plyometric [23]
Various Daily Volume, type of
exercise
Acceptable if within
defined limits
a
HSR Eccentric-concentric 4, 15–6 39/week 15–6 RM Acceptable if was not worse
after
reps repetitions, RM repetition maximum
a
Moderate (less than 5 of 10 on a visual analogue scale, 10 =worst pain imaginable); subsided by the following day
Loading of Achilles and Patellar Tendinopathy
Table 4 Group characteristics, interventions and outcomes for each study
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Alfredson et al.
[35] (1998)
CCT, AT 1. EL =15 patients, eccentric calf
drop over a step
Mean age 44 years, 80 %
men, all midportion,
unilateral and runners
12 weeks; 94 % ;in VAS pain
(p \0.001), 100 % return to
running
12 weeks; :concentric work 14 %
(p \0.05), no change in
eccentric work, :concentric
torque 11–15 % (p \0.05),
:eccentric torque 18 %
(p \0.01), torque and work
deficits resolved
2. Surgery =15 patients
Alfredson et al.
[34] (1999)
CCT, AT 1. EL =14 patients Mean age 44 years, 86 %
men, all midportion,
unilateral and runners
12 weeks: [95 % ;in VAS pain
(p \0.01)
12 weeks: concentric and eccentric
torque deficits resolved
2. Surgery =10 patients
Alfredson [51]
(2003)
SC, AT EL =6 patients Mean age 48 years,
midportion
12 weeks: 75 % ;in VAS pain 12 weeks; no change in glutamate
concentration (p [0.05)
Bahr et al. [18]
(2006)
RCT, PT 1. EL =20 tendons, eccentric
squat on a decline board
Mean age 31 years, 90 %
men and all active, 14 %
bilateral
3, 6, 12 months: 73–130 %
improvement in VISA
(p \0.001)
6, 12 months: :leg press 1RM
(kg) 17–30 % (p \0.05), no
change in SJ, CMJ in both
groups
2. Surgery =20 tendons
Cannell et al.
[29] (2001)
RCT, PT 1. Stanish and Curwin =10
patients, all patellar =fast drop
squat until thighs almost parallel
Mean age 26 years, 68 %
men, all active, 17 %
bilateral
12 weeks: VAS pain ;in both
groups (55 % versus 31 %,
p\0.01) with no difference
between the groups. More
returned to sport in drop squat
group but not significant (90 %
versus 67 %; p [0.05)
12 weeks: quadriceps concentric
torque did not increase in either
groups, hamstring concentric
torque :in both groups 14–18 %
(p \0.001), no difference
between groups
2. Isotonic =9 patients, eccentric-
concentric leg extensions and
curls
Croisier et al.
[47] (2001)
SC, AT and
PT
AT =9 patients, isolated eccentric
isokinetic calf; PT =10 patients,
isolated eccentric isokinetic
quadriceps
Mean age 28 years, 63 %
men, 84 % active, all
unilateral
10 weeks: 73 % ;in VAS pain in
AT (p \0.001); 71 % ;in VAS
in PT (p \0.001)
10 weeks: concentric and eccentric
torque, no deficit between sides
for both AT and PT, 41 % had
normalized US structure
de Jonge [22]
(2010)
RCT, AT 1. EL =34 tendons Mean age 45 years, 59 %
men, all midportion and
active, 21 % bilateral
12 months: 51 % improvement in
VISA-A (p \0.01)
12 months: no change in Doppler
prevalence (65 % at baseline,
71 % at follow-up). Baseline
Doppler not associated with
VISA-A change
2. EL ?nightsplint =36 tendons
Gardin et al. [48]
(2010)
SC, AT EL =20 patients; follow-up of
Shalabi 2004 study cohort
Mean age 49 years, 67 %
men, 38 % active, 38 %
bilateral
50 months: 95 % reported no or
improved symptoms—
improvement was significantly
better than baseline (p \0.001)
and post-eccentrics (p \0.01)
50 months: presence of
intratendinous signal ;from
60 % at baseline to 10 % at
follow-up (p \0.05).
3.50 months: no change in
tendon CSA
P. Malliaras et al.
Table 4 continued
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Jensen and Di
Fabio [26]
(1989)
RCT, PT 1. Home exercise =7 patients,
quadriceps and hamstring
stretches
Mean age 24 years, 52 %
men (more women in
group 2), all active
Change in pain not reported 8 weeks: affected: unaffected
eccentric work ratio :from 78 %
at baseline to 106 % at follow-
up. Home exercise group :from
82 % at baseline to 94 %. Non-
tendinopathy group performing
EL :from 108 % to 140 % (no p
values given). At 8 weeks
follow-up: pain frequency
(p =0.80) and intensity
(p =0.78) negatively correlated
with affected : unaffected
eccentric work ratio
2. Home exercise and quadriceps
IEL =8 patients (randomized
another group without patellar
tendinopathy into the same 2
groups)
Jonsson and
Alfredson [36]
(2005)
RCT, PT 1. EL =10 patients Mean age 25 years, 87 %
men, all active, 27 %
bilateral
12 weeks: 2 9improvement
(p \0.001) in VISA in EL group
versus no change in CL group.
More returned to sport/satisfied
in EL group (70 % versus 22 %,
p\0.05)
NA
2. CL =9 patients, identical to EL
but isolated concentric
component
Knobloch et al.
[28] (2007)
RCT, AT 1. EL =15 patients Mean age 33 years, 55 %
men, 40 % midportion
12 weeks: 48 % ;in VAS pain
(p \0.05)
12 weeks: ;post-capillary filling
pressure at 2 of 16 sites
measured 9–27 % (p \0.05), ;
capillary flow at 2 of 16 sites
31–45 % (p \0.05), oxygen
saturation no change
2. Control =5 patients
Knobloch [44]
(2007)
SC, AT EL =59 patients Mean age 49 years, 61 %
men, 83 % midportion
12 weeks: 35 % ;in VAS pain 12 weeks: ;postcapillary filling
pressure at 2 of 16 sites 19–24 %
(p \0.01), ;capillary flow at 2
of 16 sites (23–35 %) p \0.01),
oxygen saturation no change
Kongsgaard et al.
[19] (2009)
RCT, PT 1. EL =12 patients Mean age 32 years, all men
and active, 32 % bilateral
12, 26 weeks: 39-65 % :in VISA
in each group (p \0.01), no
difference between groups, EL
group more satisfied than HSR
group (70–73 % versus
22–42 %; p \0.05)
12 weeks: 12–13 % ;in tendon
AP diameter HSR group
(p \0.01), 45 % ;US colour
area in HSR (p \0.01), no
change in EL group for either.
17 % :patellar tendon CSA in
eccentric group only (p \0.05),
no change in other groups. 7 % :
quadriceps muscle CSA both
groups (p \0.01), no difference
between groups. No change in
collagen content, HP, LP
concentration in any group. :HP
: LP ratio (19 %) and ;
pentosidine (23 %) in HSR
group, no change in other
groups. 8–11 % :MVC in both
exercise groups (p \0.05). No
change in stiffness and modulus
in either exercise group
2. HSR =13 patients, leg press,
hack squat, squat—all double leg
3. CSI =12 patients, 1–2
injections
Loading of Achilles and Patellar Tendinopathy
Table 4 continued
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Kongsgaard et al.
[20] (2010)
SC, PT HSR =8 patients (compared with
a group without tendinopathy
who did not perform the
exercise)
Mean age 33 years, all men
and active
12 weeks: 27 % improvement in
VISA (p =0.02)
12 weeks: quadriceps CSA :7 %,
peak knee extension moment :
10 %, tendon stiffness ;9 % in
HSR group (p \0.05). Modulus
tended to decrease (p =0.15)
but no change in patellar tendon
CSA, strain and stress. Fibril
density :70 % (p =0.08), fibril
mean area ;26 % (p =0.04) in
HSR group, fibril volume
fraction no change. No change in
non-tendinopathy group for any
outcome
Langberg et al.
[49] (2007)
SC, AT EL =6 patients (compared with a
group without tendinopathy who
performed the same exercise)
Mean age 26 years, all
active men with
midportion symptoms, all
unilateral
12 weeks: 71 % ;in VAS pain
(p \0.05)
12 weeks: 4 9:collagen
synthesis (p \0.05). No
significant change in non-
tendinopathy group. No change
in either group in collagen
degradation
Mafi et al. [32]
(2001)
RCT, AT 1. EL =22 patients Mean age 48 years, 55 %
men, all midportion, 57 %
active
12 weeks: more satisfied/returned
to pre-injury activity in EL group
(82 % versus 36 %; p =0.002)
NA
2. Mafi combined =22 patients,
eccentric-concentric theraband
PF and heel raises, step-ups,
skipping, hopping
Niesen-
Vertommen
et al. [37]
(1992)
RCT, AT 1. Stanish and Curwin =8
patients, fast eccentric calf drop,
slow concentric component
Mean age 38 years men;
30 years women, 59 %
men (more women in
Stanish group), all
midportion and active
12 weeks: VAS pain ;in both
groups (50–72 %; p \0.05),
greater decrease in Stanish group
(p \0.01). More returned to
sport/improved activity in
Stanish and Curwin group but
not significant (75 % versus
33 %; p =0.15)
12 weeks: approximately 2 9:
concentric and eccentric torque
in both groups (p \0.001), no
difference between the groups
2. Isotonic =9 patients, eccentric-
concentric planterflexion and
dorsiflexion
Norregaard et al.
[33] (2007)
RCT, AT 1. EL =21 tendons, progressed to
faster calf drop after 3 weeks
Mean age 42 years, 51 %
men, 3–4 patients per
group had insertional,
49 % bilateral
3, 6, 12, 24, 52 weeks:
improvements in symptoms and
pain (18–76 %; p \0.01–0.05)
in both groups, no difference
between the groups
12 (not 3) months: AP ;9–17 %
(p \0.05) in both groups, no
difference between the groups.
12 months: greater AP diameter
initially associated with less pain
intensity and better quality of life
at 12 months (p \0.01), but
change in symptoms not
correlated to change in AP
2. Stretching =24 tendons, soleus
and gastrocnemius stretches
P. Malliaras et al.
Table 4 continued
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Ohberg and
Alfredson [24]
(2004)
SC, AT EL =34 patients Mean age 48 years, 76 %
men, 62 % active, all had
midportion symptoms,
37 % bilateral
Mean 28 months: 88 % had no
pain during activity
Mean 28 months: ‘more normal’
grey-scale US appearance in
90 %, Doppler signal resolved in
78 %. More likely to have
remaining Doppler if still painful
(p \0.001). Trend towards US
abnormality remaining in
tendons that were still painful
(p =0.07)
Ohberg et al.
[25] (2004)
SC, AT EL =25 patients, follow-up of
Ohberg 2004 study cohort
Mean age 50 years, 76 %
men, 72 % active, 4 %
bilateral
Mean 3.8 years: 88 % returned to
pre-injury activity/satisfied
Mean 3.8 years: AP diameter ;
14 % (p \0.005), more likely
satisfied if structure resolved
(86 % versus 5 %; p \0.001)
Paolini et al. [38]
(2004)
RCT, AT 1. EL ?placebo =33 patients Mean age 49 years, 62 %
men, all midportion, 29 %
bilateral
2, 6, 12, 24 weeks: pain (scale
from 0 to 4) with activity ;
21–61 %, VAS pain with
hopping ;29–54 % (within
group significance not reported)
2, 6, 12, 24 weeks: 2.4–2.8 9:in
ankle planterflexor mean total
work (significance not given)
2. EL ?GTN =31 patients
Peterson et al.
[39] (2007)
RCT, AT 1. EL =37 patients Mean age 43 years, 60 %
men, 92 % active, all had
midportion symptoms,
bilateral =11 %
6, 12, 54 weeks: 10–16 %
improvement in American
Orthopaedic Foot and Ankle
Assessment score, 20–60 % ;in
VAS pain with activity
(p \0.001)
12 weeks: no significant change in
tendon AP diameter
2. Airheel brace 35 patients
3. EL and Airheel brace =28
patients
Purdam et al [27]
(2004)
CCT, PT 1. EL =8 patients Mean age 25 years, 75 %
men, all active (decline
squat group older, more
females and more
bilateral injuries but not
significant)
12 weeks: VAS pain ;
significantly in the EL group
only (62 %; p \0.05). More
returned to pre-injury activity in
EL group (75 % versus 11 %;
p=0.04)
NA
2. EL without decline board =9
patients
Romero-
Rodriguez
et al. [43]
(2011)
SC, PT Flywheel =10 patients, inertial
loading using flywheel device
Mean age 25 years, all
active men, 50 % bilateral
6, 12 weeks: 86 % improvement in
VISA (p \0.01), 60 % ;in
VAS pain (p \0.01)
6 weeks: eccentric force :90 %
(p =0.03), concentric rectus
femoris EMG :73 %
(p =0.03), no change in
concentric force, eccentric rectus
femoris EMG and bilateral CMJ
height
Rompe et al. [21]
(2007)
RCT, AT 1. EL =25 patients Mean age =49 years,
40 % men, 32 % active,
all midportion, all
unilateral
16 weeks: 57 % improvement in
VISA-A (p \0.01). No
improvement in the wait-and-see
group. More patients completely
recovered or much better in the
EL (60 %) versus wait and see
group (24 %) [p \0.01]
16 weeks: no change in AP
diameter
2. ESWT =25 patients
3. Wait-and-see =25 patients
Shalabi et al.
[45] (2004)
SC, AT EL =25 patients Mean age 51 years, 64 %
men, 40 % active, all had
midportion symptoms,
32 % bilateral
12 weeks: 40 % improvement in
5-point pain scale (p \0.01)
12 weeks: tendon CSA ;14 %
(p \0.05), intratendinous signal
intensity ;23 % (p \0.05), pain
score post correlated with change
in signal/not volume
Loading of Achilles and Patellar Tendinopathy
Table 4 continued
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Silbernagel et al.
[30] (2001)
RCT, AT 1. Combined =22 patients, calf
raises, balance, then eccentric
loading, then added speed
Mean age 44 years, 77 %
men, all midportion and
active (except 1 patient in
group 2), 41 % bilateral
12, 26 weeks: VAS walking
(40 %) and pain with palpation
(29–57 %) ;in combined group
only (p \0.05)
26 weeks: VAS activity ;in both
groups (57–80 %), also ;in
combined group at 6 weeks
(44 %) [p \0.05]. 12 months:
combined group more likely
satisfied (78 % versus 38 %;
p\0.05) and considered
themselves recovered (60 %
versus 38 %, p \0.05), no
significant difference in return to
pre-injury activity (55 %
combined, 35 % calf raise/
stretching)
6, 12, 26 weeks: calf endurance :
14–30 % both groups, no group
differences. 12, 26 weeks: :
CMJ height 7–30 % both groups,
calf raise/stretching group also :
at 6 weeks, no group differences.
26 weeks: PF ROM :4%
combined group only. No change
in DF at any time
2. Calf raises and stretching =18
patients
Silbernagel et al.
[23] (2007)
RCT, AT 1. Combined =19 patients,
identical to Silbernagel 2001 but
added hopping
Mean age 46 years, 53 %
men (more women group
2), all midportion and
active, 34 % bilateral
6, 12, 24, 52 weeks: VISA-A
improvement in both groups
(p \0.01, up to 60 % combined,
up to 49 % combined ?sport),
no difference between the groups
6, 12, 26, 52 weeks: :eccentric-
concentric work 20–29 %
(p \0.05) [no :at 12 weeks in
group 1]. 12, 26, 52 weeks: :
eccentric-concentric toe-raise
power 17–26 % group 2 only
(p \0.05) [only :at 6 weeks in
group 1], no change in concentric
toe-raise power in either group.
26 weeks: :drop CMJ height
11 %, :hop quotient 27 %,
group 2 only (p \0.05). No
change in CMJ height in either
group. 6, 26 weeks: ;DF ROM
5–6 %, group 2 only (p \0.05)
2. Combined ?continued
sport =19 patients
Silbernagel et al.
[41] (2007)
SC, AT Combined =37 patients Mean age 46 years, 54 %
men, all had midportion
symptoms
12 months: 59 % improvement in
VISA-A on symptomatic side
(p \0.05), 67 % classified as
fully recovered (VISA-A C90)
12 months: low correlation
between VISA-A scores and test
battery (r =0.18; p =0.41)
(calf raise endurance, drop CMJ
height, hopping plyometric
quotient, concentric toe-raise
power, eccentric toe-raise
power). Only drop CMJ height
was significantly correlated with
VISA-A scores (r =0.178;
p=0.61, p \0.01). Among the
‘fully recovered’ patients, 25 %
had C90 % of unaffected side on
functional test battery
P. Malliaras et al.
Table 4 continued
Study (year) Design Groups, interventions Participant characteristics
a
Clinical outcome Mechanistic outcomes
Silbernagel et al.
[40] (2011)
SC, AT Combined =34 patients, follow-
up of Silbernagel 2007 study
cohort
Mean age 51 years, 53 %
men, all active and had
midportion symptoms
5 years: functional evaluation
among 13 patients who were
asymptomatic, 5 patients who
had continued symptoms
5 years: deficit between affected
and unaffected side—
asymptomatics: 9 % for
eccentric-concentric work
(p =0.09), 14 % for concentric
power (p =0.04). No deficit for
eccentric-concentric power, drop
CMJ height, hop quotient.
Continued symptomatics had an
18 % deficit for concentric
power (p =0.03)
Van der Plas
et al. [42]
(2012)
SC, AT EL =46 patients, follow-up of de
Jonge 2010 study cohort
Mean age 51 years, 91 %
active, all had midportion
symptoms, 26 % bilateral
5 years: 70 % improvement in
VISA-A from baseline
(p \0.001), 12 % improvement
in VISA-A from 1 year
(p =0.006)
5 years: AP ;7 % (p =0.051),
Doppler present 59 % baseline
and 47 % at follow-up
(p [0.05). VISA-A change and
at 5 years was not associated
with baseline Doppler. Pain
presence and VISA-A at 5 years
not correlated with baseline AP
diameter
Visnes et al. [11]
(2005)
RCT, PT 1. EL =13 active athletes Mean age 27 years, 65 %
men, volleyball players,
42 % bilateral
12, 18 weeks: no significant
change in VISA scores, no
significant difference to control
group
12 weeks: :bilateral CMJ height
(1.2 cm, p =0.046) in ET
group. SJ height (uni-, bilateral),
CMJ height (unilateral) no
change either group
2. Control =16 active athletes
Young et al. [31]
(2005)
RCT, PT 1. EL =9 active athletes Mean age 27 years, 77 %
men, volleyball players
12 months: more likely clinically
significant VISA change in EL
group (94 % versus 41 %)
NA
2. Stanish and Curwin =8 active
athletes
AP anteroposterior, AT Achilles tendon, CCT controlled trial, CL concentric loading, CMJ countermovement jump, CSA cross-sectional area, dorsiflexion, EL eccentric loading, ESWT
Extracorporeal shockwave therapy, EMG electromyographic activity, GTN glycerol tri-nitrate, HSR heavy slow resistance, HP hydroxylysyl piridinoline, IEL isokinetic eccentric loading, LP
lysyl pyridinoline, MRI magnetic resonance imaging, MVC maximal voluntary contraction, NA not applicable, PF planterflexion, PT patellar tendon, RCT randomized controlled trial, ROM
range of motion, RM repetition maximum, SC single cohort, SJ squat jump, US ultrasound imaging, VAS visual analogue score, VISA Victorian Institute of Sport Assessment, VISA-A VISA-
Achilles version
:, indicates increase; ;, indicates decrease
a
Mean age, gender, uni-versus bilateral, midportion versus insertion (for AT only) and activity. All imaging studies use ultrasound except for Shalabi et al. [101] and Gardin et al. [48] (MRI)
Loading of Achilles and Patellar Tendinopathy
calf endurance and jump performance is greater with Sil-
bernagel-combined loading versus calf raises/stretching
[30]. There is moderate evidence from one high-quality and
three-low quality studies, showing that (i) improved clinical
outcomes are associated with improved jump performance
[23,30] (ii) improved clinical outcomes are associated with
increased calf power [23] (iii) calf power and jump perfor-
mance is greater with Silbernagel-combined loading when
sport is continued [23] (iv) improvement in clinical
outcomes is not associated with resolution in side-to-side
deficits in various functional measures (planterflexor
endurance, torque, power and work, jump and hop tests) [40,
41]. There is conflicting clinical evidence from one high-
quality and one low-quality study that improved clinical
outcomes are associated with increased planterflexion and
decreased dorsiflexion range of motion [23,30].
3.3.1.1.3 Other Loading. There is limited evidence from
one low-quality study that improved clinical outcomes are
associated with increased planterflexor torque following
Stanish and Curwin loading but not isotonic loading [37],
and increased planterflexor torque following isokinetic
loading [47].
3.3.1.2 Imaging Measures
3.3.1.2.1 Eccentric Loading. There is conflicting evi-
dence from seven low-quality studies, which show that
improved clinical outcomes are associated with
(i) decreased anteroposterior diameter [21,25,33,39,42];
(ii) a decrease in the proportion of tendons containing
Doppler signal [22,24,42] (one study is high quality and
shows no change in the proportion of tendons containing
Doppler signal) [22]. There is conflicting evidence from two
low-quality studies that investigate the same cohort at dif-
ferent times and found that improved clinical outcomes are
associated with decreased cross-sectional area (CSA) [45,
48]. There was only one high-quality study that showed no
change in tendon dimensions in association with reduced
symptoms (anteroposterior diameter) [21]. There is mod-
erate evidence from one high-quality and four low-quality
studies, which show that (i) imaging (Doppler presence and
anteroposterior diameter at baseline, change in anteropos-
terior diameter) does not predict a change in symptoms
[22,33,42] (ii) improved clinical outcomes following
isokinetic loading are associated with decreased intraten-
dinous signal intensity [45,48].
3.3.1.2.2 Other Loading. There is limited evidence from
one low-quality study that improved clinical outcomes
following isokinetic loading are associated with a decrease
in the proportion of abnormal tendons on greyscale ultra-
sound [47].
3.3.1.3 Biochemical and Blood Flow
3.3.1.3.1 Eccentric Loading. There is limited evidence
from two low-quality studies, showing that improved
clinical outcomes are associated with (i) an increase in type
I collagen synthesis [49], but not associated with reduced
glutamate concentration [51]; (ii) reduced Achilles tendon
capillary blood flow and post-capillary filling pressure [44].
3.3.2 Patellar
3.3.2.1 Neuromuscular and Jump Performance Outcomes
3.3.2.1.1 Eccentric Loading. There is moderate evidence
from two high-quality studies, which showed that improved
clinical outcomes are associated with (i) increased knee
extensor torque [19]; (ii)increased leg press 1-repetition
maximum (1RM) [18]; (iii) increased quadriceps muscle
CSA [19]. There is conflicting evidence from two high-
quality studies that improved clinical outcomes are not
associated with improved jump performance [11,18].
3.3.2.1.2 Heavy-Slow Resistance (HSR) Loading. There
is strong evidence from two high-quality studies that
improved clinical outcomes are associated with increased
knee extensor torque [19,20]. There is moderate evidence
from one high-quality study that improved clinical out-
comes are associated with increased quadriceps muscle
CSA [19].
3.3.2.1.3 Stanish and Curwin Loading. There is limited
evidence from one low-quality study that improved clinical
outcomes are associated with increased knee flexor but not
extensor torque [29]. There is limited evidence from one
low-quality study that there is no group difference in
change in knee flexor and extensor torque between Stanish
and Curwin and isotonic loading [29].
3.3.2.1.4 Other Loading. There is limited evidence from
two low-quality studies, which showed that; (i) torque
deficits resolve following isokinetic loading [47] (ii)
improved clinical outcomes are associated with increased
eccentric force on a flywheel device (but not concentric
force), but no change in jump performance following fly-
wheel loading [43].
3.3.2.2 Imaging, Structural and Mechanical Property
Outcomes
3.3.2.2.1 Eccentric Loading. There is moderate evidence
from one high-quality study, which showed that
(i) improved clinical outcomes are not associated with
reduced Doppler area and anteroposterior diameter [19];(ii)
P. Malliaras et al.
increase in CSA is greater following eccentric, compared
with HSR loading [19];(iii) improved clinical outcomes are
not associated with change in tendon stiffness and modulus
[19].
3.3.2.2.2 HSR. There is moderate evidence from two
high-quality studies, which showed that improved clinical
outcomes are associated with (i) reduced Doppler area and
anteroposterior diameter [19]; (ii) increased fibril density,
decreased fibril mean area and no change in fibril volume
fraction [20]. There is conflicting evidence from two high-
quality studies that improved clinical outcomes are asso-
ciated with a decrease in tendon stiffness and modulus
[19,20].
3.3.2.3 Biochemical Outcomes
3.3.2.3.1 Eccentric Loading. There is moderate evidence
from one high-quality study that improved clinical out-
comes are not associated with change in collagen content,
hydroxylysyl pyridinoline (HP) and lysyl pyridinoline (LP)
concentration, HP/LP ratio, and pentosidine concentration
[19].
3.3.2.3.2 HSR Loading. There is moderate evidence
from one high-quality study that collagen content, HP and
LP concentration do not change but HP/LP ratio increases
and pentosidine concentration decreases alongside
improved clinical outcomes [19].
4 Discussion
4.1 Comparison of Loading Programmes
Ten studies were identified that compared loading pro-
grammes in Achilles and patellar tendinopathy. Only two
studies, both investigating patellar tendinopathy, were high
quality [11,19]. Although the Alfredson eccentric loading
model is a popular clinical intervention, there is limited
evidence in the Achilles tendon to support its use when
compared with other loading programmes. There was
limited evidence from one study that patient satisfaction/
return to preinjury activity is greater following eccentric
compared with concentric loading in the Achilles tendon
[32]. This evidence should be interpreted with caution, as
the concentric group performed different exercises that are
likely to have involved a much lower load (i.e. non- or
partial weightbearing initially). The Silbernagel-combined
loading programme incorporates eccentric-concentric,
eccentric and then faster loading and has been investigated
in four Achilles tendon studies. There is limited evidence
that this programme offers superior clinical outcomes to
eccentric-concentric calf raises and stretching alone [30]. It
is important for clinicians to appreciate that there is as
much evidence for the Silbernagel-combined programme
as there is for the Alfredson eccentric programme when
comparing them to other loading programmes in Achilles
tendinopathy. The gradual progression from eccentric-
concentric to eccentric followed by faster loading may
benefit patients who are unable to start with an Alfredson
eccentric programme due to pain or calf weakness.
In the patellar tendon, there is conflicting evidence that
eccentric loading is superior to other loading programmes.
There is limited evidence that VISA improvement is
greater following eccentric loading compared with con-
centric loading [36], and Stanish and Curwin loading [31]
in patellar tendinopathy. However, there is moderate evi-
dence that eccentric loading is equivalent on VISA out-
comes and inferior on patient subjective satisfaction to
HSR loading [19]. HSR loading is performed three times
per week rather than twice daily, and this may explain the
greater patient satisfaction. Good-quality evidence is
lacking for both Achilles and patellar tendinopathy, but
there is clearly benefit from loading programmes that
involve eccentric-concentric muscle actions.
Some studies investigated tendon loading prior or during
a competition phase. Young et al. [31] found that slow
eccentric decline squats preseason, led to superior post-
volleyball season patellar tendon VISA outcomes than that
of the Stanish and Curwin loading. Visnes et al. [11] found
eccentric decline squatting did not improve patellar tendon
VISA outcomes when performed during a volleyball sea-
son. Silbernagel et al. [23] found continued sport activity
did not compromise clinical outcomes at 12 months, as
long as sport was gradually introduced to ensure minimal
pain during and after loading. Continuing sport with
rehabilitation may be more successful in Achilles tenden-
opathy, as sport load may be lower than typical patellar
tendon loads in some sports (e.g. volleyball).
4.2 Mechanisms of Achilles and Patellar Tendon
Loading Programmes
4.2.1 Neuromuscular Performance and Muscle Size
Loading was shown to be associated with improved neu-
romuscular outcomes (e.g. 1RM torque) in most studies.
The highest level of evidence supported eccentric and
Silbernagel-combined loading in the Achilles (moderate
evidence) [23,30,34,35] and HSR loading in the patellar
tendon (strong evidence) [19,20]. There is limited evi-
dence for Stanish and Curwin and isokinetic loading in the
Achilles [37,47] and evidence for eccentric (moderate) and
flywheel (limited) in the patellar tendon [19,43]. There is
also limited evidence that quadriceps size increase is
Loading of Achilles and Patellar Tendinopathy
similar following HSR and eccentric loading in the patellar
tendon [19]. Overall, Silbernagel and eccentric loading in
the Achilles and HSR loading in the patellar have the
highest level of evidence for improving neuromuscular
function in Achilles and patellar tendinopathy.
Although eccentric loading is often linked with greater
muscle-tendon unit load and adaptation, this systematic
review did not identify any evidence of this among ten-
dinopathy patients. Among normal participants, eccentric
loading results in greater muscle strength gains and
hypertrophy (especially type II fibres) than concentric
loading [52], but not when the load is equalized [52],
suggesting load intensity rather than contraction type is the
stimulus. There is an unfounded perception among many
clinicians that eccentric muscle action always leads to
greater muscle-tendon unit load than concentric and iso-
metric contractions. During eccentric muscle action, there
are less active motor units than concentric contraction
when external load and speed are constant, with less
resultant muscle EMG activity [53,54] and oxygen con-
sumption [55,56]. This increases the force potential with
eccentric contraction, but this potential can only be realized
via the following two mechanisms:(i) if the external load is
greater than the maximal concentric and isometric load
capability; and (ii) by increasing the speed of eccentric
contraction under load, as predicted by the force-velocity
curve [55,57] (Fig. 2). For example, when a sprinter
increases running speed the hamstring muscle-tendon
during limb deceleration will increase. Therefore, clinical
eccentric loading among tendinopathy patients may not
lead to a greater change in neuromuscular outcomes
because load intensity is often not maximized [11,19,45].
Clinically, the load potential of eccentric contractions may
be limited by symptom irritability.
4.2.2 Power and Jump Performance
There is moderate evidence, which shows that calf power
and jump performance improves alongside symptoms fol-
lowing Silbernagel-combined loading but only at 6 months
[23,30], and there is moderate evidence, which shows that
improvement in both outcomes is greater if sport is con-
tinued [23]. Continued sport, as long as symptoms are
stable, seems to have a specific effect on these power
outcomes, which is not gained even with the Silbernagel-
combined programme that includes faster calf loading and
stretch-shorten cycle rehabilitation. In contrast, there is
moderate evidence that jump performance is not associated
with clinical improvement in patellar tendinopathy fol-
lowing eccentric [11,18], and limited evidence following
flywheel loading [43], even though sport was continued in
these studies based on pain monitoring. A recent systematic
review found some evidence for increased vertical jump
performance in patellar tendon patients compared with
asymptomatic cohorts, which may partly explain this
finding [58].
4.2.3 Do Side-to-Side Neuromuscular and Jump
Performance Deficits Resolve?
Side-to-side deficits (e.g. torque, work, endurance) were
only evaluated in the Achilles tendon. There is moderate
[34,35,47] evidence that deficits resolve in the short term
(10–12 weeks), but also that they are present at longer-term
follow up (12 months to 5 years) [40,41]. It is possible that
deficits recur when rehabilitation ceases, indicating that
performance may need to be maintained with ongoing
loading.
4.2.4 Imaging, Structure and Biochemicals
The only evidence for change in imaging measures in the
Achilles tendon is decreased intratendinous signal inten-
sity on magnetic resonance imaging (MRI) following
eccentric loading (moderate evidence) [45,48]. This
review did not identify any evidence that tendon dimen-
sions (anteroposterior diameter, CSA) and the proportion
of tendons with Doppler signal change following Achilles
eccentric loading, despite limited evidence for increased
collagen type 1 production. In the patellar tendon,
improved clinical outcomes were not associated with
reduced Doppler area and anteroposterior diameter in
eccentric loading, but they were following HSR (moderate
evidence) [19]. There is also moderate evidence, that HSR
Fig. 2 Force velocity curve. L
O
isometric length, P
O
maximum
isometric tension, V
max
maximum velocity (reproduced from Leiber
[57], with permission from Lippincott, Williams and Wilkins)
P. Malliaras et al.
is less likely to lead to increased patellar tendon CSA, and
more likely to lead to increased pentosidine concentration
and HP/LP ratio, indicative of collagen turnover [19]. This
suggests that HSR has a more positive effect on tendon
adaptation and remodelling if increased CSA is interpreted
as increased pathology in the eccentric loading group. The
effect of HSR on tendon adaptation is supported by
moderate evidence of improved clinical outcomes along-
side ‘normalization’ of tendon microstructure (increased
fibril density, decreased fibril mean area) in patellar ten-
dinopathy [20].
HSR appears to be a promising intervention for tendon
adaptation, although it should be highlighted that it is only
investigated in two studies, both in the patellar tendon.
VISA change was similar in the HSR and eccentric loading
groups, despite evidence for greater tendon adaptation with
HSR [19]. Improved tendon structure may reduce the risk
of recurrence. Future research is needed to explore this
possibility. Pathology may improve spontaneously among
tendons that are less progressed on the tendon pathology
continuum [59] but, perhaps, HSR is more likely to bring
about adaptation of more severely pathological tendons and
partly or fully restore the loss of tendon stiffness observed
in pathological tendons [60]. Tendons with less severe
pathology have a better clinical and pathology prognosis
and vice versa [6163]; therefore, it is presumed there may
be clinical benefit in improving severely abnormal tendon
pathology if this was possible.
A likely explanation of the superior tendon adaptation
with HSR may be increased load. HSR probably involved
heavier tendon load (maximum load =6RM in HSR
versus 15 kg in eccentric loading (Kongsgaard M et al.,
personal communication), and tendon and muscle response
are known to be load dependent. Kubo et al [64] compared
identical volume and intensity of isometric quadriceps
loading in 50"and 100"knee flexion. Patellar tendon
moment arm, and therefore tendon force, was greater in
100", and only this group demonstrated increased tendon
stiffness. Arampatzis et al. [65,66] found that an increase
in tendon stiffness following chronic eccentric-concentric
heavy loading was diminished at higher strain frequency
(i.e. faster contraction, less time under tension, tendon
strained less during loading). Tendon is viscoelastic and is
more compliant (i.e. strains more) with longer duration
and heavier contractions [67,68], and strain is thought to
be the stimulus for tendon adaptation [66]. The current
systematic review, however, found conflicting evidence for
change in tendon stiffness following HSR [19,20], and no
evidence following eccentric loading, despite evidence for
biochemical adaptation (e.g. HP/LP ratio) [19]. This sug-
gests structure and material property changes may be
different or delayed in pathological tendons.
4.2.5 Muscle-Tendon Unit Compliance and Length-
Tension Relationship
Although there is conflicting evidence for change in dor-
siflexion and planterflexion range with Silbernagel-com-
bined loading in this systematic review [23,30], Mahieu
et al [69] reported an increase in ankle dorsiflexion range of
motion and muscle-tendon unit compliance (reduced
resistance to passive stretch) after 6 weeks of eccentric
loading performed without any additional load (i.e. body-
weight only) among normal participants. Increased range
of motion has been demonstrated in other studies following
eccentric [6971] and eccentric-concentric loading [72],
and other authors report both increased [73] and decreased
[74] muscle-tendon unit compliance after chronic loaded
eccentrics. Eccentric contraction has also been widely
reported to lead to a rightwards shift of the length-tension
curve (greater force potential at longer lengths) [7578]
(Fig. 3) and increased sarcomere length [7881], and sar-
comeres in series [8284]. Similar changes have been
demonstrated with concentric loading [78]. Clarifying
whether contraction type, load intensity or other factors
such as loading range of motion influence these outcomes,
and whether they relate to clinical outcomes in tendinop-
athy, may improve effectiveness in tendinopathy rehabili-
tation. For example, a loading programme that achieves
increased muscle-tendon unit compliance may lead to
superior clinical outcomes among Achilles patients with
reduced calf muscle-tendon unit compliance. The chal-
lenge may be the complex interaction between these factors
(e.g. a ballet dancer with an excessive range of motion but
reduced muscle-tendon unit compliance) and how to
measure them clinically (e.g. muscle-tendon unit
compliance).
Fig. 3 Length–tension curve (muscle force is optimal near the mid-
joint range and reduces at inner and outer joint ranges). Reproduced
from Leiber [57], with permission from Lippincott, Williams and
Wilkins
Loading of Achilles and Patellar Tendinopathy
4.2.6 Blood Flow
Hypoxia has been implicated in the pathogenesis of tendin-
opathy and, therefore, change in microvasculature has been
investigated as a potential mechanism of eccentric loading.
Although there is limited evidence that Achilles capillary
flow and post-capillary pressure decreased following
12 weeks of eccentric loading, this finding was only seen at
13 % of the 16 anatomical sites around the Achilles tendon
that were evaluated [28,44]. Furthermore, a recent study
showed women had greater vascular improvement (decrease
in post-capillary pressures) than men but less symptomatic
response following eccentric loading [85,86], questioning
the link between this potential mechanism and pain.
4.2.7 Pain System
Alfredson et al. [35] hypothesized that aggressive, painful
eccentric calf drops have a direct mechanical effect on
neurovascular ingrowth that may be a source of pain [87].
There is no evidence that such a direct mechanical effect
modulates pain, and this systematic review did not identify
any evidence that a change in glutamate may explain
clinical outcomes in Achilles tendinopathy. However, the
popular rehabilitation approach of exposing tendon tissues
to progressively more eccentric loading and SSC loading
whilst monitoring and avoiding tendon irritability, is likely
to have some effect on the nervous system and pain per-
ception. This may be a change in local biochemicals that
has not yet been studied, or central nervous system changes
(e.g. increased inhibitory neuron activation, cortical reor-
ganization) [88].
4.2.8 Are Isolated Eccentric Contractions Justified
Clinically?
This review found only limited evidence from one study in
the Achilles tendon, and conflicting evidence in the patellar
tendon, which showed that isolating eccentric muscle
contraction is superior to other loading [19,31,32,36], and
no evidence that mechanistic outcomes improve more
following eccentric loading compared with other forms of
loading. In fact, there is moderate evidence that imaging
outcomes (Doppler area and anteroposterior diameter) may
improve more following HSR compared with eccentric
loading in the patellar tendon [19]. This may, in part, be
because, as discussed in Sect. 4.2.1, load intensity does not
seem to be maximized with clinical eccentric loading, and
muscle and tendon adaptation seems to be dependent on
load intensity. Nonetheless, the findings of this review
suggest clinical improvement is not dependent on isolated
eccentric loading in Achilles and patellar tendinopathy
rehabilitation.
There may be, however, other mechanisms of eccentric
muscle contractions that do not relate to load potential and
were not investigated in any of the studies in this review.
Eccentric contractions result in greater neural changes than
concentric loading, including greater strength gains in the
contralateral limb [89,90], faster neural adaptation from
strength loading [89,91] and increased cortical excitability
[92]. These changes may account for some of the early
neuromuscular gains in the clinical literature (e.g. 6 weeks
[43]). An interesting recent finding is that there are tendon
force fluctuations (8–12 Hz) with eccentric contraction that
are absent in concentric contraction [54,93]. It is not
known whether they influence muscle-tendon adaptation or
are simply inherent in motor control differences (reduced
active motor units with eccentric contractions). Finally,
even if load potential is not maximized, load progression
may be easier and faster with eccentric loading, particu-
larly with the mechanical and metabolic advantages. Given
these potential mechanisms and the evidence base sur-
rounding submaximal eccentric loading [6], there may be
an indication for isolating the eccentric component even
with lower-load loading, but underlying mechanisms are
not evidence based and need to be investigated.
There are potential issues with isolated eccentric muscle
contraction. Delayed onset muscle soreness (DOMS) is a
recognized side effect of eccentric loading, which is neg-
ligible with isometric and concentric contraction due to the
absence of negative work [94]. DOMS can be minimized
with graded exposure to eccentric muscle contractions. A
potentially more serious issue with isolated eccentric
muscle contractions in clinical populations is training
specificity. Muscle training gains are known to be specific
to the mode of contraction, speed and joint angle [95]. This
is a particular issue in clinical populations with poorer
concentric strength, who may have reduced carry-over of
eccentric-to-concentric strength gains, limiting clinical
outcomes and prolonging dysfunction and pain.
5 Clinical Implications
Clinicians should consider eccentric-concentric loading
alongside or instead of eccentric loading in Achilles and
patellar tendinopathy. Eccentric-concentric loading may be
particularly important among patients with marked concentric
weakness that may not recover with isolated eccentric loading,
due to muscle contraction type specificity. The Silbernagel-
combined programme seems an ideal progressive loading
programme for this patient subgroup. Heavy load training, as
in HSR or load maximized eccentric loading, may be more
likely to achieve tendon adaptation and may be better suited to
some patient groups (e.g. less irritable or degenerative tendon
symptoms, high-load demands such as athletes).
P. Malliaras et al.
In the Achilles tendon, continued sport may lead to
specific gains that are less evident with other loading (e.g.
greater improvements in jump performance). Although
SSC load and continued sport has the potential to aggravate
symptoms, it seems to be important in the rehabilitation
process and should be implemented carefully alongside a
sensible pain monitoring system [23].
Pain was an acceptable feature of rehabilitation in most
studies in this review. In the Alfredson model, the goal is to
increase the load until it is painful. In other models (e.g.
HSR, Silbernagel combined) the goal is to progress the
load so that pain is tolerated as long as it settles quickly.
Equivalent or greater improvement in HSR and Silberna-
gel-combined loading programmes suggests that pain does
not need to be the focus of loading interventions. The
health professional has an important role in educating
patients about acceptable loading-related symptoms.
Some studies reported continued neuromuscular and
jump performance deficits at 12 months and 5 years, which
may initially relate to inadequate loading or a lack of
appropriate maintenance loading. This questions the length
of current loading programmes and suggests suitable
maintenance programmes may be necessary even when
patients return to sport.
6 Future Directions
This review has highlighted a dearth of clinical evidence
comparing rehabilitation programmes in Achilles and
patellar tendinopathy. Rather than accepting isolated
eccentric loading as the gold standard, studies are needed
to investigate how load intensity, time under tension,
speed, contraction type and other factors influence clinical
and mechanistic outcomes. Potential confounders need to
be identified and controlled, and also a change in symp-
toms, long-term clinical outcomes and recurrence corre-
lated with change in potential mechanisms. Further,
correlated mechanistic outcomes need to be investigated in
prospective intervention studies to determine if they are
causally linked with improved clinical outcomes. It is
important to consider when planning future studies that
tendons at different points along the symptomatic reactive-
degenerative spectrum may respond very differently to
loading interventions.
No studies have investigated isometric loading in ten-
dinopathy. During isometric contraction, time under ten-
sion can be maximized to allow greater tendon strain,
which is a likely stimulus for tendon adaptation. Further,
DOMS is minimal, loading can be performed in a range
that is not painful and tendon compression can be mini-
mized. Tendon compression that occurs near the end of
joint range is thought to be involved in pathoetiology of
insertional tendinopathy [9698]. A potential disadvantage
is joint angle-specific strength gains [99,100], although
carry-over to other angles is greater when loading is not
performed at optimal length-tension range. Given the
potential benefits of isometric loading, it warrants investi-
gation in clinical studies.
Various subgroups may also benefit from different
loading programmes. For example, end-of-range loading
may change muscle-tendon unit compliance and the length-
tension relationship, which may potentially have a positive
effect on clinical outcomes in some patient groups. Patients
with concentric weakness may benefit from concentric-
eccentric loading rather than isolated eccentric loading, at
least initially. Some patients may have greater potential for
tendon adaptation (e.g. younger, healthier) and may
respond more to heavy loading. Clarifying these potential
effects in clinical populations may allow subgrouping of
patients into rehabilitation programmes based on specific
deficits, ultimately improving clinical effectiveness.
There is a paucity of evidence relating to change in
central and peripheral pain mechanisms with Achilles and
patellar tendinopathy rehabilitation. There has long been
debate regarding the source of pain in tendinopathy and
current evidence suggests that neurovascular ingrowth, as
well as endocrine tenocytes, may have a role in local
production of pain biochemicals. Several questions remain.
Do change in biochemicals other than glutamate (e.g.
substance P), or central changes (e.g. cortical reorganiza-
tion) influence symptomatic response with rehabilitation?
Does painful loading facilitate these changes?
7 Conclusion
This systematic review has identified limited and conflict-
ing evidence that clinical outcomes are superior with
eccentric loading compared with other loading pro-
grammes in Achilles and patellar tendinopathy, respec-
tively, questioning the currently entrenched clinical
approach to these injuries. There is equivalent evidence for
Silbernagel-combined (Achilles) and greater evidence for
HSR loading (patellar).
Improved neuromuscular performance (e.g. torque,
work, endurance) was consistently associated with
improved clinical outcomes so may partly explain clinical
benefit with Achilles and patellar tendon rehabilitation. For
this non-clinical outcome, Silbernagel-combined and
eccentric (Achilles tendon) as well as HSR loading
(patellar tendon) had the highest level of evidence.
Improved jump performance was associated with Achilles
but not patellar tendon clinical outcomes. In contrast,
improved imaging outcomes such as anteroposterior
diameter and Doppler signal/area were associated with
Loading of Achilles and Patellar Tendinopathy
patellar tendon (HSR only) but not Achilles clinical out-
comes. HSR was also associated with greater evidence of
collagen turnover when compared with eccentric loading.
The mechanisms associated with clinical benefit may vary
between loading interventions and tendons. HSR appears to
be a promising intervention for tendon adaptation but
caution is needed in interpreting findings as only two
studies, both in the patellar tendon, investigate this loading
intervention.
This systematic review found that there is at least
equivalent clinical evidence, and greater evidence for
improvement in some potential mechanisms such as neu-
romuscular performance and imaging following eccentric-
concentric compared with isolated eccentric loading. This
suggests that there is little clinical or mechanistic evidence
for isolating the eccentric component, although it should be
made clear that there is a paucity of good-quality evidence,
and several potential mechanisms, such as neural adapta-
tion and central nervous system changes (e.g. cortical
reorganization), have not been investigated. Among
asymptomatic participants, load intensity, which can be
maximized with eccentric loading, may be a stimulus for
muscle-tendon adaptation, but this is often not optimized in
clinical studies, perhaps due to symptom irritability.
Acknowledgments The authors have no conflict of interest to
declare that are directly relevant to the content of this review. No
funding was received or used to assist in the preparation of this
review.
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Supplementary resource (1)

... Several different types of ECC exercise for the rehabilitation of AT are known, among which Alfredson's heavy-load eccentric calf muscle training (HECT) is the most commonly used [27]. On the other hand, many physiotherapists use either ISOM exercise [31,32], ISOT exercise (i.e., heavy slow resistance (HSR) exercise, the Silbernagel combined protocol, and the Stanish and Curwin protocol) [33], CON exercise [34,35], or the combination of two or more of the mentioned protocols [33]. Similarly, great results for treating either IAT or MAT were found after executing acupuncture treatment [36,37], ESWT treatment [36,38], cold air and high-energy laser therapy [15,39], physiotherapy and massage treatment [39,40], etc. ...
... The results of methodological quality are presented as the rating of overall confidence in the range from critically low overall confidence to high overall confidence (Table S1). Twenty-seven articles had critically low overall confidence [14][15][16]28,31,32,34,35,38,40,[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], 8 articles had low overall confidence [29,39,[62][63][64][65][66][67], none of the included studies had moderate overall confidence, and 16 out of 50 articles had high overall confidence [11,12,30,33,36,37,[68][69][70][71][72][73][74][75][76][77]. ...
... The authors of 21 out of the 50 studies were focused on the effects of conservative nonpharmacological treatments for treating MAT [11,12,[29][30][31][32][33][34]40,[51][52][53]55,56,58,66,68,70,73,76,77]. ECC exercise, characterized by lengthening of the muscle with a purpose to maintain a certain load or because external resistance/load becomes greater than the force produced by the muscle [78,79], was found to be effective as a rehabilitation protocol for treating MAT, as it caused a significant decrease in pain, an improvement in function [29,32,51,77], an improvement in tendon properties (e.g., increase in tendon volume, decrease in tendon cross-sectional area, decrease in free tendon diameter, reduced tendon post-capillary filling pressure and capillary blood flow, increase in type I collagen synthesis, and reduction in tendon neovascularization) [32,51,53,55], an increase in strength [34], and an improvement in ankle performance [55], and it caused an improvement in patient satisfaction compared to a baseline [29]. ...
Article
Full-text available
Achilles tendinopathy (AT) is the most common injury of the Achilles tendon and represents 55–65% of all Achilles tendon clinical diagnoses. AT is characterized by pain, swelling, and impaired performance. ATs can be divided into two types, according to anatomical location—midportion AT (MAT) and insertional AT (IAT). MAT more often occurs in older, less active, and overweight populations, while IAT usually occurs in the more physically active population. Both types of AT can be treated by different treatments, such as surgery, conservative pharmacological treatments, and conservative nonpharmacological treatments. This umbrella review aims to assemble the evidence from all available systematic reviews and/or meta-analyses to determine which conservative nonpharmacological treatments are most commonly used and have the greatest effects. Three major electronic scientific databases (PubMed, Scopus, and Web of Science) were screened. The reference lists of several recent articles on AT were also searched. We found 50 articles that met the inclusion criteria. The methodological quality of the included articles was assessed using the AMSTAR 2 tool. Eccentric (ECC) exercise, isotonic (ISOT) exercise, and acupuncture treatment showed the greatest effects for treating MAT as a standalone therapy. Meanwhile, extracorporeal shockwave therapy and ECC exercise provided the best outcomes for treating IAT as individual treatments. However, an even greater pain decrease, greater function improvement, and greater patient satisfaction for treating either MAT or IAT were achieved with combined protocols of ECC exercise with extracorporeal shockwave therapy (in both cases), ECC exercise with cold air and high-energy laser therapy (in the case of IAT), or ECC exercise with ASTYM therapy (in the case of IAT).
... The concept of resistance training using isolated eccentric actions to treat lower limb tendinopathy was first suggested by Stanish et al., (1986) [229] and then later popularised by the publication of the Alfredson eccentric heel-drop protocol for Achilles tendinopathy [230]. Since then, eccentric resistance training has become the most explored and recommended method for treating Achilles and patellar tendinopathies, due to consistently positive findings for pain and function improvement [231,232]. The training parameters of the Alfredson eccentric heel-drop protocol have also been applied to patellar tendinopathy in the form of an eccentric single-leg decline squat protocol, which has shown clinical efficacy [233,234]. ...
Article
Full-text available
Tendinopathy is a chronic tendon disease which can cause significant pain and functional limitations for individuals, and which collectively places a tremendous burden on society. Resistance training has long been considered the treatment of choice in the rehabilitation of chronic tendinopathies, with both eccentric and heavy slow resistance training demonstrating positive clinical effects. The application of progressive tendon loads during rehabilitation is essential to not compromise tendon healing, with the precise dosage parameters of resistance training and external loading a critical consideration. Blood-flow restriction training (BFRT) has become an increasingly popular method of resistance training in recent years and has been shown to be an effective method for enhancing muscle strength and hypertrophy in healthy populations and in musculoskeletal rehabilitation. Traditional resistance training for tendinopathy requires the application of heavy training loads, whereas BFRT utilises significantly lower loads and training intensities, which may be more appropriate for certain clinical populations. Despite evidence confirming the positive muscular adaptations derived from BFRT and the clinical benefits found for other musculoskeletal conditions, BFRT has received a dearth of attention in tendon rehabilitation. Therefore, the purpose of this narrative review was threefold: firstly, to give an overview and analysis of the mechanisms and outcomes of BFRT in both healthy populations and in musculoskeletal rehabilitation. Secondly, to give an overview of the evidence to date on the effects of BFRT on healthy tendon properties and clinical outcomes when applied to tendon pathology. Finally, a discussion on the clinical utility of BFRT and its potential applications within tendinopathy rehabilitation, including as a compliment to traditional heavy-load training, is presented.
... Furthermore, conflicting results about intratendinous neovascularization which is supposed to coincide with tendinopathy. On the one hand, a correlation of neovascularization with clinical severity has been reported [80] and there is evidence that a reduction in neovessels by treatment with sclerosing agents improves clinical findings [81]. On the other hand, no correlation between neovascularization and pain or function (i.e., VISA-A score) has been found at baseline in an intervention trial with 37% of the symptomatic tendons showing no neovascularization [82], demonstrating the difficulty when concluding from neovascularization to clinical severity [83]. ...
Article
Full-text available
Background Assuming that the mechanisms inducing adaptation in healthy tendons yield similar responses in tendinopathic tendons, we hypothesized that a high-loading exercise protocol that increases tendon stiffness and cross-sectional area in male healthy Achilles tendons may also induce comparable beneficial adaptations in male tendinopathic Achilles tendons in addition to improving pain and function. Objectives We investigated the effectiveness of high-loading exercise in Achilles tendinopathy in terms of inducing mechanical (tendon stiffness, maximum strain), material (Young’s modulus), morphological (tendon cross-sectional area (CSA)), maximum voluntary isometric plantar flexor strength (MVC) as well as clinical adaptations (Victorian Institute of Sports Assessment—Achilles (VISA-A) score and pain (numerical rating scale (NRS))) as the primary outcomes. As secondary outcomes, drop (DJ) and counter-movement jump (CMJ) height and intratendinous vascularity were assessed. Methods We conducted a controlled clinical trial with a 3-month intervention phase. Eligibility criteria were assessed by researchers and medical doctors. Inclusion criteria were male sex, aged between 20 and 55 years, chronic Achilles tendinopathy confirmed by a medical doctor via ultrasound-assisted assessment, and a severity level of less than 80 points on the VISA-A score. Thirty-nine patients were assigned by sequential allocation to one of three parallel arms: a high-loading intervention (training at ~ 90% of the MVC) (n = 15), eccentric exercise (according to the Alfredson protocol) as the standard therapy (n = 15) and passive therapy (n = 14). Parameters were assessed pre- and-post-intervention. Data analysis was blinded. Results Primary outcomes: Plantar flexor MVC, tendon stiffness, mean CSA and maximum tendon strain improved only in the high-loading intervention group by 7.2 ± 9.9% (p = 0.045), 20.1 ± 20.5% (p = 0.049), 8.98 ± 5.8% (p < 0.001) and −12.4 ± 10.3% (p = 0.001), respectively. Stiffness decreased in the passive therapy group (−7.7 ± 21.2%; p = 0.042). There was no change in Young’s modulus in either group (p > 0.05). The VISA-A score increased in all groups on average by 19.8 ± 15.3 points (p < 0.001), while pain (NRS) dropped by −0.55 ± 0.9 points (p < 0.001). Secondary outcomes: CMJ height decreased for all groups (−0.63 ± 4.07 cm; p = 0.005). There was no change in DJ height and vascularity (p > 0.05) in either group. Conclusion Despite an overall clinical improvement, it was exclusively the high-loading intervention that induced significant mechanical and morphological adaptations of the plantar flexor muscle–tendon unit. This might contribute to protecting the tendon from strain-induced injury. Thus, we recommend the high-loading intervention as an effective (alternative) therapeutic protocol in Achilles tendinopathy rehabilitation management in males. Clinical Trials Registration Number: NCT02732782.
... After identifying 398 articles 23 articles were analyzed, 3 prospective studies (n = 115), 2 case-control studies (n = 258) and 18 controlled clinical trials (n = 889) also were consulted 9 systematic reviews [7,[32][33][34][35][36][37][38][39], as well as a Clinical Practice Guidelines [40] (Figure 1). ...
Chapter
The effectiveness of various physical therapies in the conservative treatment of Achilles tendinopathy are reviewed.
... However, studies show that the long-term results of surgical therapy do not differ from those of conservative therapy and that operative treatments have a higher risk of other complications [15]. The best evidence for treating AT is available for loading exercises (ie, eccentric-concentric loading) [16]; for all other forms of therapy, evidence is contradictory or anecdotal. Overall, it must be concluded that the optimal treatment strategies for chronic AT are still being debated and that treatments are protracted and mostly unsatisfactory. ...
Article
Background: The consensus of the optimal treatment strategy for chronic Achilles tendinopathy (AT) is still debated and treatment options are limited. This results in a significant medical need for more effective treatment options. Objective: The aim of this study is to investigate the therapeutic effects of percutaneous bioelectric current stimulation (PBCS) on AT. Methods: A multi-center, randomized, double-blind, placebo-controlled clinical trial will be conducted. A total of 72 participants with chronic (>3 months) midpoint AT will be randomized and receive 4 PBCS (either verum or placebo) over 3 weeks. Both groups will complete daily Achilles tendon loading exercises in addition to the intervention. Evaluation sessions will be completed at baseline and intervention (weeks 0-3). Self-reported outcome measures will be completed at the follow-up in weeks 4, 12, 26, 52.Primary outcome: Victorian Institute of Sports Assessment - Achilles Questionnaire(Version: VISA-A) score: Statistical evaluation of intraindividual differences between baseline and 12 weeks after initial treatment after verum therapy compared to control. Secondary outcomes will assess pain disability index (PDI), average pain (11-point numeric rating scale - NRS), return to sports, and use of emergency medication. Results: Study began in May 2021. As of October 2022, we randomized 66 out of 72 participants. We anticipate completing recruiting in the fourth quarter of 2022 and primary data analysis in the first quarter of 2023. Conclusions: The study will evaluate the effects of PBCS on pain, physical function and clinical outcomes. Clinicaltrial: DRKS, DRKS00017293. Registered 1. February 2022. Retrospectively registered, https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00017293.
... The effectiveness of NSAID in PT is not clear yet (Schwartz, Watson & Hutchinson, 2015), and long-term studies have reported adverse effects (Magra & Maffulli, 2006). On the other side, EE (Larsson et al., 2012;Gaida & Cook, 2011;Malliaras et al., 2013), stretching (Medeiros et al., 2016), and other invasive therapeutic strategies such as platelet-rich plasma (Anitua, Sánchez & Orive, 2010), intratissue percutaneous electrolysis (EPI) and EE (Abat et al., 2014), ultrasound-guided galvanic electrolysis technique (USGET) (Abat et al., 2016), high-volume infiltrations (Maffulli et al., 2016), ultrasound and extracorporeal shockwave therapy (ESWT) (Han recorded in a training diary. When participants scored 3 points or less in VAS, the load was increased with a weight vest of 5 kg. ...
Article
Full-text available
Background: Patellar tendinopathy (PT) is an injury with a high prevalence in athletes that causes pain, loss of strength and sport performance levels. Purpose: to analyse the effects of 8 weeks of a conservative physical rehabilitation program that combine eccentric exercise (EE), stretching, extracorporeal shockwave therapy (ESWT), and manual therapy on tendon tissue, perceived pain, and muscle power and strength in athletes diagnosed with PT. Material and methods: Eight athletes diagnosed with PT, performed 8 weeks of EE, stretching, and ESWT. At the beginning (PRE), at 4-weeks (INT), and at the end of the 8-week intervention (POST), participants performed a countermovement jump test (CMJ), and a gradual back squat (BS) test to determine peak power (PP), mean velocity in PP (PPMV), and load lifted (PPKG). Furthermore, a maximum test of 5-repetition (5-RM) was evaluated in leg extension exercise, perceived pain using the Victorian Institute of Sport Assessment-Patella scale (VISA-P), and thickness in the injured and uninjured knee. Results: It was reported a lower tendon thickness POST vs. PRE in the injured knee (p=0.045), and lower values compared to the uninjured knee at PRE (p=0.004), and INT (p=0.025), but not POST (p=0.123). The CMJ and 5-RM tests showed statistical differences POST vs. PRE, and INT (p<0.05). Regarding BS, differences were reported in PPKG POST vs PRE (p=0.033), and INT (p = 0.007), while in PP differences were found in POST vs PRE (p=0.037). Conclusions: 8 weeks of EE, stretching, ESWT, and manual therapy induce positive effects on tendon tissue healing, lower limbs muscle power and strength performance in athletes with PT.
Thesis
La survenue d’altérations neuromusculaires et musculo tendineuses lors d’épreuves de course à pied de fond s’avère être délétère sur la capacité de performance d’endurance et la période de récupération des athlètes. Par ailleurs, la sévérité de ces perturbations peut être exacerbée par les caractéristiques du terrain, et plus particulièrement par la présence de dénivelé négatif. En course à pied de descente, l’amplitude plus importante de ces altérations est sous-tendue par la prédominance du régime de contraction excentrique à l’exercice. Dès lors, la course à pied de descente constitue un challenge pour les coureurs dans leur quête d’excellence athlétique, aussi bien à l’entraînement que lors d’épreuves compétitives. L’exploration de stratégies préventives, ayant pour objectif de mieux tolérer les sections de course à pied en descente, apparaît donc pleinement justifiée dans le domaine de l’optimisation des réponses adaptatives en course à pied. Dans ce contexte, une première analyse prospective de la littérature a focalisé sur l’exploration des stratégies de répétitions de sessions (c.-à-d., usage chronique de la course à pied en descente) et du port in situ de textiles vestimentaires à visée ergogénique (e.g., textiles de compression et réflecteurs de rayons infrarouges lointains). Étant donné que l’usage chronique de la course à pied en descente pourrait également permettre l’instauration d’adaptations bénéfiques sur la capacité de performance des athlètes, il convenait au préalable de préciser les adaptations neuromusculaires et musculo-tendineuses à l’entraînement de course à pied en descente. Ainsi, les objectifs du travail de thèse étaient de caractériser les adaptations neuromusculaires et musculo-tendineuses à l’entraînement de course à pied en descente d’une part, et d’enrichir nos connaissances sur l’apport de stratégies préventives dans le domaine de la course à pied de fond, d’autre part. Les résultats de ce travail ont montré que : (i) l’entraînement de course à pied en descente (4 semaines) peut instaurer de rapides adaptations neuromusculaires (e.g., gains de force, hypertrophie musculaire) et tendineuses (par exemple, augmentation de la raideur du tendon patellaire), sans pour autant atténuer la sévérité des perturbations neuromusculaires à l’issue d’une session de course à pied en descente ; (ii) que le port de textiles de compression à l’exercice peut exercer un « effet protecteur dynamique » sur les groupes musculaires compressés, sans pour autant atténuer les perturbations de la capacité de performance d’endurance des athlètes ; et (iii) que le port de textiles réflecteurs de rayons infrarouges à l’exercice pourrait générer certains effets ergogéniques mais que la compréhension de leurs effets reste à ce jour globalement limitée.
Article
Objectives: To estimate Achilles tendon forces and their relationship with self-reported pain in runners with Achilles tendinopathy (AT) during common rehabilitation exercises. Design: Cross-sectional. Setting: Laboratory. Participants: 24 recreational male runners (45.92 (8.24) years old; 78.20 (8.01) kg; 177.17 (6.69) cm) with symptomatic AT. Main outcome measures: Kinematic and kinetic data were collected to estimate Achilles tendon forces during 12 commonly prescribed exercises. Achilles tendon forces were estimated from biomechanical data and normalised to the participant's bodyweight. The secondary aim was to investigate the relationship between Achilles tendon forces and pain during these exercises. Results: Two exercise clusters were identified based on Achilles tendon forces. Cluster1 included various exercises including double heel raises, single heel raises, and walking (range: 1.10-2.76 BWs). Cluster2 included running, jumping and hopping exercises (range: 5.13-6.35 BWs). Correlation between tendon forces and pain was at best low for each exercise (range: -0.43 - 0.20). Higher force exercises lead to more tendon load for a given amount of pain (R2 = 0.7505; y = 0.2367x + 0.6191). Conclusion: This study proposes a hierarchical exercise progression based on Achilles tendon forces to guide treatment of runners with AT. Achilles tendon forces and pain are not correlated in runners with AT.
Article
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Achilles tendinopathy (AT) is a debilitating injury in athletes, especially for those engaged in repetitive stretch-shortening cycle activities. Clinical risk factors are numerous, but it has been suggested that altered biomechanics might be associated with AT. No systematic review has been conducted investigating these biomechanical alterations in specifically athletic populations. Therefore, the aim of this systematic review was to compare the lower-limb biomechanics of athletes with AT to athletically matched asymptomatic controls. Databases were searched for relevant studies investigating biomechanics during gait activities and other motor tasks such as hopping, isolated strength tasks, and reflex responses. Inclusion criteria for studies were an AT diagnosis in at least one group, cross-sectional or prospective data, at least one outcome comparing biomechanical data between an AT and healthy group, and athletic populations. Studies were excluded if patients had Achilles tendon rupture/surgery, participants reported injuries other than AT, and when only within-subject data was available.. Effect sizes (Cohen's d) with 95% confidence intervals were calculated for relevant outcomes. The initial search yielded 4,442 studies. After screening, twenty studies (775 total participants) were synthesised, reporting on a wide range of biomechanical outcomes. Females were under-represented and patients in the AT group were three years older on average. Biomechanical alterations were identified in some studies during running, hopping, jumping, strength tasks and reflex activity. Equally, several biomechanical variables studied were not associated with AT in included studies, indicating a conflicting picture. Kinematics in AT patients appeared to be altered in the lower limb, potentially indicating a pattern of "medial collapse". Muscular activity of the calf and hips was different between groups, whereby AT patients exhibited greater calf electromyographic amplitudes despite lower plantar flexor strength. Overall, dynamic maximal strength of the plantar flexors, and isometric strength of the hips might be reduced in the AT group. This systematic review reports on several biomechanical alterations in athletes Frontiers in Sports and Active Living 01 frontiersin.org with AT. With further research, these factors could potentially form treatment targets for clinicians, although clinical approaches should take other contributing health factors into account. The studies included were of low quality, and currently no solid conclusions can be drawn.
Article
Full-text available
Systematic reviews should build on a protocol that describes the rationale, hypothesis, and planned methods of the review; few reviews report whether a protocol exists. Detailed, well-described protocols can facilitate the understanding and appraisal of the review methods, as well as the detection of modifications to methods and selective reporting in completed reviews. We describe the development of a reporting guideline, the Preferred Reporting Items for Systematic reviews and Meta-Analyses for Protocols 2015 (PRISMA-P 2015). PRISMA-P consists of a 17-item checklist intended to facilitate the preparation and reporting of a robust protocol for the systematic review. Funders and those commissioning reviews might consider mandating the use of the checklist to facilitate the submission of relevant protocol information in funding applications. Similarly, peer reviewers and editors can use the guidance to gauge the completeness and transparency of a systematic review protocol submitted for publication in a journal or other medium.
Article
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The role of the perception of breathing effort in the regulation of performance of maximal exercise remains unclear. To determine whether the perceived effort of ventilation is altered through substituting a less dense gas for normal ambient air and whether this substitution affects performance of maximal incremental exercise in trained athletes. Eight highly trained cyclists (mean SD) maximal oxygen consumption (VO(2)max) = 69.9 (7.9) (mlO(2)/kg/min) performed two randomised maximal tests in a hyperbaric chamber breathing ambient air composed of either 35% O(2)/65% N(2) (nitrox) or 35% O(2)/65% He (heliox). A ramp protocol was used in which power output was incremented at 0.5 W/s. The trials were separated by at least 48 h. The perceived effort of breathing was obtained via Borg Category Ratio Scales at 3-min intervals and at fatigue. Oxygen consumption (VO(2)) and minute ventilation (V(E)) were monitored continuously. Breathing heliox did not change the sensation of dyspnoea: there were no differences between trials for the Borg scales at any time point. Exercise performance was not different between the nitrox and heliox trials (peak power output = 451 (58) and 453 (56) W), nor was VO(2)max (4.96 (0.61) and 4.88 (0.65) l/min) or maximal V(E) (157 (24) and 163 (22) l/min). Between-trial variability in peak power output was less than either VO(2)max or maximal V(E). Breathing a less dense gas does not improve maximal performance of exercise or reduce the perception of breathing effort in highly trained athletes, although an attenuated submaximal tidal volume and V(E) with a concomitant reduction in VO(2) suggests an improved gas exchange and reduced O(2) cost of ventilation when breathing heliox.
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We finally solved our copyright problems to make this book available in a eVersion that you can download! This is the same as the 3rd edition in print but the copyright reverted to me and I have posted it on the Shirley Ryan AbilityLab to download for a nominal $20 (US Dollars) that goes to the AbilityLab. Enjoy! https://www.sralab.org/academy/bookstore/skeletal-muscle-structure-function-and-plasticity
Article
Achilles tendinopathy is a common overuse injury in athletes, especially older athletes. This condition is difficult to treat and often becomes chronic. This evidence based review summarized the current pathophysiological principles guiding research as well as clinical practice and synthesized the search results to determine if eccentric exercises were effective in the treatment of patients with Achilles tendinopathy. Seven studies were identified, but only two were randomized clinical trials (level A evidence) with the rest controlled clinical studies or prospective cohort studies (level B evidence). Only one study reported follow-up one year beyond the intervention period. Based on a crossectinal analysis of post treatment outcomes, there was modest but significant clinical benefits following eccentric exercise training, but insufficient evidence to predict the long-term effects of eccentric exercise training for the management of Achilles tendinopathy. Although randomized clinical trials with a large subject population are still needed, eccentric exercise paired with biomedical training techniques should be integrated into treatment guidelines for patients with Achilles tendonitis.
Article
This study examined the angular specificity and test mode specificity of strength training. Six males and six females (X̄ = 22.6 years) were assigned to groups which trained either isometrically (90°) or isokinetically (30°/second). They trained their left elbow extensors at 80% of their maximum voluntary contraction on a modified Cybex® apparatus for 10 weeks, three sessions per week, with 50 contractions per session. Before and after training, both groups were tested isometrically (70, 90, 110°) and isokinetically (30°/second). When tested isometrically, both groups improved equally, and strength was increased at all three test angles to about the same extent. When tested isokinetically, both groups improved, but the isokinetic group improved to a greater extent. In conclusion, no angular specificity of training was demonstrated within 20° of the training angle, and no test mode specificity was seen for isometric testing. However, isometric training showed less transfer to an isokinetic test.