achilles and patellar tendinopathy loading programmes · conclusion there is little clinical or...

SYSTEMATIC REVIEW

Achilles and Patellar Tendinopathy Loading Programmes

A Systematic Review Comparing Clinical Outcomes and Identifying PotentialMechanisms for Effectiveness

Peter Malliaras • Christian J. Barton •

Neil D. Reeves • Henning Langberg

! Springer International Publishing Switzerland 2013

AbstractIntroduction Achilles and patellar tendinopathy areoveruse 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 toeccentric (Silbernagel combined) and eccentric-concentric

isotonic (heavy-slow resistance; HSR) loading have also

been investigated. In order for clinicians to make informeddecisions, 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 patientdeficits and refine loading programmes in future studies.

Objectives The objectives of this review are to evaluatethe evidence in studies that compare two or more loadingprogrammes in Achilles and patellar tendinopathy, and to

review the non-clinical outcomes (potential mechanisms),

such as improved imaging outcomes, associated withclinical 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 yieldincluded 32 studies; ten compared loading programmes and

28 investigated at least one potential mechanism (six

studies compared loading programmes and investigatedpotential mechanisms).

Results This review has identified limited (Achilles) andconflicting (patellar) evidence that clinical outcomes aresuperior with eccentric loading compared with other

loading programmes, questioning the currently entrenched

clinical approach to these injuries. There is equivalentevidence for Silbernagel combined (Achilles) and greater

evidence for HSR loading (patellar). The only potential

mechanism that was consistently associated with improvedclinical 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. Inthe Achilles tendon, a majority of studies did not find an

association between improved imaging (e.g. reduced

anteroposterior diameter, proportion of tendons withDoppler signal) and clinical outcomes, including all high-

quality studies. In contrast, HSR loading in the patellar

tendon was associated with reduced Doppler area andanteroposterior 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 tendonadaptation 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 thisarticle (doi:10.1007/s40279-013-0019-z) contains supplementarymaterial, which is available to authorized users.

P. Malliaras (&) ! C. J. BartonCentre for Sports and Exercise Medicine, Mile End Hospital,Queen Mary, University of London, London, UKe-mail: [email protected]

N. D. ReevesInstitute for Biomedical Research into Human Movementand Health, Manchester Metropolitan University,Manchester, UK

H. LangbergInstitute of Sports Medicine, Bispebjerg Hospital,Copenhagen, Denmark

Sports Med

DOI 10.1007/s40279-013-0019-z

http://dx.doi.org/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 qualityevidence and several potential mechanisms have not been

investigated, such as neural adaptation and central nervous

system changes (e.g. cortical reorganization). Cliniciansshould 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 ordecreased), break down in the extracellular matrix (ground

substance accumulation, disorganized collagen, neurovas-

cular ingrowth) [1, 2]. Endocrine tenocytes and nerveendings 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) maypredispose to injury, but pathoaetiology is poorly under-

stood [5].

Eccentric muscle loading has become the dominantconservative 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 [6–10] and patellar

[11, 12] tendinopathy, concluding that outcomes arepromising 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 Achillesand 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 beeffective for all patients with tendinopathy. Understanding

the mechanisms of loading interventions in tendinopathy,

and which mechanisms are associated with improvedclinical 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, CurrentContents and SPORTDiscus

TM

electronic databases was

undertaken from inception to June 2012. Search terms

relating to exercise (‘eccentric’, ‘rehabilitation’, ‘resistancetraining’, ‘exercise therapy’), pathology (‘tendinopathy’,

‘tendinitis’, etc.) and the site (‘Achilles’, ‘patellar’) were

combined in the final search (Table 1 shows the MEDLINEexample). Each search term was mapped to specific MeSH

subject headings within each database. The reference lists

of eccentric loading systematic reviews and the studies inthe 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 yieldstudies 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 mechanisticoutcome (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 includednon-English studies, abstracts, non-peer-reviewed studies,

case reports and reviews.

2.3 Review Process

Two reviewers (PM, CB) independently reviewed the titleand abstract of all retrieved studies and those satisfying the

inclusion and exclusion criteria were included in the finalyield. 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 byconsensus.

2.4 Quality Assessment

A modified version [15] of a scale developed to assess the

quality of intervention studies in patellofemoral joint painsyndrome [16] was used to evaluate study quality. Four

quality components were evaluated (participants, inter-

ventions, outcome measures, and data presentation andanalysis), 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 torelate 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 exerciseintervention 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 wasscored 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 keygroup 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 qualityassessment were considered high quality.

2.5 Data Extraction and Analysis

Key data relating to sample demographics, interventions

and outcomes were extracted from each study. Thisincluded 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 outcomemeasures a qualitative data synthesis was performed.

Definitions for ‘levels of evidence’ were guided by rec-

ommendations made by van Tulder et al. [17] and areshown in Table 2.

3 Results

Figure 1 shows the process of identifying studies. Therewere 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 33studies 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 comparingloading 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 therange was from 26 % to 83 %. Only seven (21 %) studies

achieved a high-quality rating [11, 18–23]. Five (15 %)

Table 1 Search terms in MEDLINE database

Search term

1 ‘eccentric’, ‘concentric’, ‘isometric’, ‘training’, ‘exercise’ (title & abstract) ‘Exercise Therapy’, ‘Exercise’, ‘Rehabilitation’, ‘Resistancetraining’ (MeSH)

AND

2 ‘achilles tendon’, ‘achilles’, ‘tendoachilles’, ‘tendo-achilles’, ‘triceps-surae’, ‘patellar tendon’, ‘patellar ligament’ (title & abstract) ‘AchillesTendon’, ‘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 % [24–28] and find-

ings from these studies were not included in the recom-

mended levels of evidence. Eleven (55 %) trials wereadequately randomized [11, 18, 19, 21–23, 29–33]. Three

studies did not randomize participants into groups [27, 34,

35], and the remaining studies did not adequately describethe randomization process [26, 28, 36–39]. Only seven

studies (21 %) reported adequate blinding of outcomeassessors [19–23, 29, 38], so experimenter bias may have

influenced the findings in a majority of studies. Only two

studies (6 %) adequately reported inclusion and exclusioncriteria [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-twopercent (14 of 33) used adequate outcome measures [11,

19–23, 30, 31, 36, 39–43]. 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 andvalidated pain and functional outcome measure (0–100

points, 100 = no pain and full function). Most studies

described the loading interventions partially, with the meanscore 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 thisliterature 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 [21–25, 28, 30, 32–35, 37–42, 44,

45, 47–49, 51] and 11 patellar tendon studies [11, 18–20,26, 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 theeccentric-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 toeccentric load and, finally, faster eccentric-concentric and

plyometric loading. Two patellar tendon studies [19, 20]

(20 %) investigated heavy-slow resistance (HSR) loadingthat involves slow double leg isotonic eccentric-concentric

contractions. Table 3 shows the characteristics of the four

main loading programmes used in Achilles and patellartendinopathy 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 loadingprogrammes

Evidencegrade

Recommendation

Strong Consistent findings among n C2 high-quality studies

Moderate Consistent findings amongst multiple low-qualitystudies, 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 abstract16 animal studies7 cruciate ligament repair83 opinion pieces, abstracts, case studies, reviews113 post-surgery, rupture, other treatment79 no-exercise intervention3

other study scored just below the cut off for a high-quality

rating (68 %) [31].

Data extracted from each study comparing loadingprogrammes 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 programmesin 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 followingeccentric, compared with concentric, loading [32]; (ii)

VAS pain outcomes and patient satisfaction are greater

following Silbernagel-combined loading compared withcalf 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 onehigh-quality study there was moderate evidence, which

showed that VISA-A improvement following Silbernagel-

combined loading is similar whether sport is continued ornot [23].

There were six patellar tendon studies including 112

participants with a mean age of 27 years. All participantswere 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 improvementis 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 seasonwith 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 Stanishand 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 [21–25, 28,

30, 33–35, 37–42, 44, 45, 48, 49, 51] and patellar tendin-opathy [11, 18–20, 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 % (range26–79 %) and seven studies (25 %) had a high-quality

rating [11, 18–22, 42]. There were 293 participants with

Achilles tendinopathy in 21 studies. They had a mean age of47 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 amean 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 planterflexiontorque [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 upto moderate pain

Stanish and Curwin Eccentric-concentric, power 3, 10–20 Daily Speed then load Enough load to be painfulin third set

Silbernagel Eccentric-concentric, eccentric, fastereccentric-concentric, balanceexercise [30, 41], plyometric [23]

Various Daily Volume, type ofexercise

Acceptable if withindefined limitsa

HSR Eccentric-concentric 4, 15–6 39/week 15–6 RM Acceptable if was not worseafter

reps repetitions, RM repetition maximuma Moderate (less than 5 of 10 on a visual analogue scale, 10 = worst pain imaginable); subsided by the following day


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1%

atfo

llo

w-u

p).

Bas

elin

eD

op

ple

rn

ot

asso

ciat

edw

ith

VIS

A-A

chan

ge

2.

EL

?n

igh

tsp

lin

t=

36

ten

do

ns

Gar

din

etal

.[4

8](2

01

0)

SC

,A

TE

L=

20

pat

ien

ts;

foll

ow

-up

of

Sh

alab

i2

00

4st

ud

yco

ho

rtM

ean

age

49

yea

rs,

67

%m

en,

38

%ac

tiv

e,3

8%

bil

ater

al

50

mo

nth

s:9

5%

rep

ort

edn

oo

rim

pro

ved

sym

pto

ms—

imp

rov

emen

tw

assi

gn

ifica

ntl

yb

ette

rth

anb

asel

ine

(p\

0.0

01

)an

dp

ost

-ecc

entr

ics

(p\

0.0

1)

50

mo

nth

s:p

rese

nce

of

intr

aten

din

ou

ssi

gn

al;

fro

m6

0%

atb

asel

ine

to1

0%

atfo

llo

w-u

p(p

\0

.05

).3

.50

mo

nth

s:n

och

ang

ein

ten

do

nC

SA

P. Malliaras et al.

Tab

le4

con

tin

ued

Stu

dy

(yea

r)D

esig

nG

rou

ps,

inte

rven

tio

ns

Par

tici

pan

tch

arac

teri

stic

saC

lin

ical

ou

tco

me

Mec

han

isti

co

utc

om

es

Jen

sen

and

Di

Fab

io[2

6](1

98

9)

RC

T,

PT

1.

Ho

me

exer

cise

=7

pat

ien

ts,

qu

adri

cep

san

dh

amst

rin

gst

retc

hes

Mea

nag

e2

4y

ears

,5

2%

men

(mo

rew

om

enin

gro

up

2),

all

acti

ve

Ch

ang

ein

pai

nn

ot

rep

ort

ed8

wee

ks:

affe

cted

:u

naf

fect

edec

cen

tric

wo

rkra

tio:

fro

m7

8%

atb

asel

ine

to1

06

%at

foll

ow

-u

p.

Ho

me

exer

cise

gro

up:

fro

m8

2%

atb

asel

ine

to9

4%

.N

on

-te

nd

ino

pat

hy

gro

up

per

form

ing

EL:

fro

m1

08

%to

14

0%

(no

pv

alu

esg

iven

).A

t8

wee

ks

foll

ow

-up

:p

ain

freq

uen

cy(p

=0

.80

)an

din

ten

sity

(p=

0.7

8)

neg

ativ

ely

corr

elat

edw

ith

affe

cted

:u

naf

fect

edec

cen

tric

wo

rkra

tio

2.

Ho

me

exer

cise

and

qu

adri

cep

sIE

L=

8p

atie

nts

(ran

do

miz

edan

oth

erg

rou

pw

ith

ou

tp

atel

lar

ten

din

op

ath

yin

toth

esa

me

2g

rou

ps)

Jon

sso

nan

dA

lfre

dso

n[3

6](2

00

5)

RC

T,

PT

1.

EL

=1

0p

atie

nts

Mea

nag

e2

5y

ears

,8

7%

men

,al

lac

tiv

e,2

7%

bil

ater

al

12

wee

ks:

29

imp

rov

emen

t(p

\0

.00

1)

inV

ISA

inE

Lg

rou

pv

ersu

sn

och

ang

ein

CL

gro

up

.M

ore

retu

rned

tosp

ort

/sat

isfi

edin

EL

gro

up

(70

%v

ersu

s2

2%

,p\

0.0

5)

NA

2.

CL

=9

pat

ien

ts,

iden

tica

lto

EL

bu

tis

ola

ted

con

cen

tric

com

po

nen

t

Kn

ob

loch

etal

.[2

8]

(20

07

)R

CT

,A

T1

.E

L=

15

pat

ien

tsM

ean

age

33

yea

rs,

55

%m

en,

40

%m

idp

ort

ion

12

wee

ks:

48

%;

inV

AS

pai

n(p

\0

.05

)1

2w

eek

s:;

po

st-c

apil

lary

fill

ing

pre

ssu

reat

2o

f1

6si

tes

mea

sure

d9

–2

7%

(p\

0.0

5),;

cap

illa

ryfl

ow

at2

of

16

site

s3

1–

45

%(p

\0

.05

),o

xy

gen

satu

rati

on

no

chan

ge

2.

Co

ntr

ol

=5

pat

ien

ts

Kn

ob

loch

[44]

(20

07

)S

C,

AT

EL

=5

9p

atie

nts

Mea

nag

e4

9y

ears

,6

1%

men

,8

3%

mid

po

rtio

n1

2w

eek

s:3

5%

;in

VA

Sp

ain

12

wee

ks:

;p

ost

cap

illa

ryfi

llin

gp

ress

ure

at2

of

16

site

s1

9–

24

%(p

\0

.01

),;

cap

illa

ryfl

ow

at2

of

16

site

s(2

3–

35

%)

p\

0.0

1),

ox

yg

ensa

tura

tio

nn

och

ang

e

Ko

ng

sgaa

rdet

al.

[19

](2

00

9)

RC

T,

PT

1.

EL

=1

2p

atie

nts

Mea

nag

e3

2y

ears

,al

lm

enan

dac

tiv

e,3

2%

bil

ater

al1

2,

26

wee

ks:

39

-65

%:

inV

ISA

inea

chg

rou

p(p

\0

.01

),n

od

iffe

ren

ceb

etw

een

gro

up

s,E

Lg

rou

pm

ore

sati

sfied

than

HS

Rg

rou

p(7

0–

73

%v

ersu

s2

2–

42

%;

p\

0.0

5)

12

wee

ks:

12

–1

3%

;in

ten

do

nA

Pd

iam

eter

HS

Rg

rou

p(p

\0

.01

),4

5%

;U

Sco

lou

rar

eain

HS

R(p

\0

.01

),n

och

ang

ein

EL

gro

up

for

eith

er.

17

%:

pat

ella

rte

nd

on

CS

Ain

ecce

ntr

icg

rou

po

nly

(p\

0.0

5),

no

chan

ge

ino

ther

gro

up

s.7

%:

qu

adri

cep

sm

usc

leC

SA

bo

thg

rou

ps

(p\

0.0

1),

no

dif

fere

nce

bet

wee

ng

rou

ps.

No

chan

ge

inco

llag

enco

nte

nt,

HP

,L

Pco

nce

ntr

atio

nin

any

gro

up

.:

HP

:L

Pra

tio

(19

%)

and;

pen

tosi

din

e(2

3%

)in

HS

Rg

rou

p,

no

chan

ge

ino

ther

gro

up

s.8

–1

1%

:M

VC

inb

oth

exer

cise

gro

up

s(p

\0

.05

).N

och

ang

ein

stif

fnes

san

dm

od

ulu

sin

eith

erex

erci

seg

rou

p

2.

HS

R=

13

pat

ien

ts,

leg

pre

ss,

hac

ksq

uat

,sq

uat

—al

ld

ou

ble

leg

3.

CS

I=

12

pat

ien

ts,

1–

2in

ject

ion

s


Tab

le4

con

tin

ued

Stu

dy

(yea

r)D

esig

nG

rou

ps,

inte

rven

tio

ns

Par

tici

pan

tch

arac

teri

stic

saC

lin

ical

ou

tco

me

Mec

han

isti

co

utc

om

es

Ko

ng

sgaa

rdet

al.

[20

](2

01

0)

SC

,P

TH

SR

=8

pat

ien

ts(c

om

par

edw

ith

ag

rou

pw

ith

ou

tte

nd

ino

pat

hy

wh

od

idn

ot

per

form

the

exer

cise

)

Mea

nag

e3

3y

ears

,al

lm

enan

dac

tiv

e1

2w

eek

s:2

7%

imp

rov

emen

tin

VIS

A(p

=0

.02

)1

2w

eek

s:q

uad

rice

ps

CS

A:

7%

,p

eak

kn

eeex

ten

sio

nm

om

ent:

10

%,

ten

do

nst

iffn

ess;

9%

inH

SR

gro

up

(p\

0.0

5).

Mo

du

lus

ten

ded

tod

ecre

ase

(p=

0.1

5)

bu

tn

och

ang

ein

pat

ella

rte

nd

on

CS

A,

stra

inan

dst

ress

.F

ibri

ld

ensi

ty:

70

%(p

=0

.08

),fi

bri

lm

ean

area

;2

6%

(p=

0.0

4)

inH

SR

gro

up

,fi

bri

lv

olu

me

frac

tio

nn

och

ang

e.N

och

ang

ein

no

n-t

end

ino

pat

hy

gro

up

for

any

ou

tco

me

Lan

gb

erg

etal

.[4

9]

(20

07

)S

C,

AT

EL

=6

pat

ien

ts(c

om

par

edw

ith

ag

rou

pw

ith

ou

tte

nd

ino

pat

hy

wh

op

erfo

rmed

the

sam

eex

erci

se)

Mea

nag

e2

6y

ears

,al

lac

tiv

em

enw

ith

mid

po

rtio

nsy

mp

tom

s,al

lu

nil

ater

al

12

wee

ks:

71

%;

inV

AS

pai

n(p

\0

.05

)1

2w

eek

s:4

9:

coll

agen

syn

thes

is(p

\0

.05

).N

osi

gn

ifica

nt

chan

ge

inn

on

-te

nd

ino

pat

hy

gro

up

.N

och

ang

ein

eith

erg

rou

pin

coll

agen

deg

rad

atio

n

Mafi

etal

.[3

2]

(20

01

)R

CT

,A

T1

.E

L=

22

pat

ien

tsM

ean

age

48

yea

rs,

55

%m

en,a

llm

idp

ort

ion

,57

%ac

tiv

e

12

wee

ks:

mo

resa

tisfi

ed/r

etu

rned

top

re-i

nju

ryac

tiv

ity

inE

Lg

rou

p(8

2%

ver

sus

36

%;

p=

0.0

02

)

NA

2.

Mafi

com

bin

ed=

22

pat

ien

ts,

ecce

ntr

ic-c

on

cen

tric

ther

aban

dP

Fan

dh

eel

rais

es,

step

-up

s,sk

ipp

ing

,h

op

pin

g

Nie

sen

-V

erto

mm

enet

al.

[37

](1

99

2)

RC

T,

AT

1.

Sta

nis

han

dC

urw

in=

8p

atie

nts

,fa

stec

cen

tric

calf

dro

p,

slo

wco

nce

ntr

icco

mp

on

ent

Mea

nag

e3

8y

ears

men

;3

0y

ears

wo

men

,5

9%

men

(mo

rew

om

enin

Sta

nis

hg

rou

p),

all

mid

po

rtio

nan

dac

tiv

e

12

wee

ks:

VA

Sp

ain;

inb

oth

gro

up

s(5

0–

72

%;

p\

0.0

5),

gre

ater

dec

reas

ein

Sta

nis

hg

rou

p(p

\0

.01

).M

ore

retu

rned

tosp

ort

/im

pro

ved

acti

vit

yin

Sta

nis

han

dC

urw

ing

rou

pb

ut

no

tsi

gn

ifica

nt

(75

%v

ersu

s3

3%

;p

=0

.15

)

12

wee

ks:

app

rox

imat

ely

29

:co

nce

ntr

ican

dec

cen

tric

torq

ue

inb

oth

gro

up

s(p

\0

.00

1),

no

dif

fere

nce

bet

wee

nth

eg

rou

ps

2.

Iso

ton

ic=

9p

atie

nts

,ec

cen

tric

-co

nce

ntr

icp

lan

terfl

exio

nan

dd

ors

iflex

ion

No

rreg

aard

etal

.[3

3]

(20

07

)R

CT

,A

T1

.E

L=

21

ten

do

ns,

pro

gre

ssed

tofa

ster

calf

dro

paf

ter

3w

eek

sM

ean

age

42

yea

rs,

51

%m

en,

3–

4p

atie

nts

per

gro

up

had

inse

rtio

nal

,4

9%

bil

ater

al

3,

6,

12

,2

4,

52

wee

ks:

imp

rov

emen

tsin

sym

pto

ms

and

pai

n(1

8–

76

%;

p\

0.0

1–

0.0

5)

inb

oth

gro

up

s,n

od

iffe

ren

ceb

etw

een

the

gro

up

s

12

(no

t3

)m

on

ths:

AP;

9–

17

%(p

\0

.05

)in

bo

thg

rou

ps,

no

dif

fere

nce

bet

wee

nth

eg

rou

ps.

12

mo

nth

s:g

reat

erA

Pd

iam

eter

init

iall

yas

soci

ated

wit

hle

ssp

ain

inte

nsi

tyan

db

ette

rq

ual

ity

of

life

at1

2m

on

ths

(p\

0.0

1),

bu

tch

ang

ein

sym

pto

ms

no

tco

rrel

ated

toch

ang

ein

AP

2.

Str

etch

ing

=2

4te

nd

on

s,so

leu

san

dg

astr

ocn

emiu

sst

retc

hes

P. Malliaras et al.

Tab

le4

con

tin

ued

Stu

dy

(yea

r)D

esig

nG

rou

ps,

inte

rven

tio

ns

Par

tici

pan

tch

arac

teri

stic

saC

lin

ical

ou

tco

me

Mec

han

isti

co

utc

om

es

Oh

ber

gan

dA

lfre

dso

n[2

4](2

00

4)

SC

,A

TE

L=

34

pat

ien

tsM

ean

age

48

yea

rs,

76

%m

en,

62

%ac

tiv

e,al

lh

adm

idp

ort

ion

sym

pto

ms,

37

%b

ilat

eral

Mea

n2

8m

on

ths:

88

%h

adn

op

ain

du

rin

gac

tiv

ity

Mea

n2

8m

on

ths:

‘mo

ren

orm

al’

gre

y-s

cale

US

app

eara

nce

in9

0%

,D

op

ple

rsi

gn

alre

solv

edin

78

%.

Mo

reli

kel

yto

hav

ere

mai

nin

gD

op

ple

rif

stil

lp

ain

ful

(p\

0.0

01

).T

ren

dto

war

ds

US

abn

orm

alit

yre

mai

nin

gin

ten

do

ns

that

wer

est

ill

pai

nfu

l(p

=0

.07

)

Oh

ber

get

al.

[25

](2

00

4)

SC

,A

TE

L=

25

pat

ien

ts,

foll

ow

-up

of

Oh

ber

g2

00

4st

ud

yco

ho

rtM

ean

age

50

yea

rs,

76

%m

en,

72

%ac

tiv

e,4

%b

ilat

eral

Mea

n3

.8y

ears

:8

8%

retu

rned

top

re-i

nju

ryac

tiv

ity

/sat

isfi

edM

ean

3.8

yea

rs:

AP

dia

met

er;

14

%(p

\0

.00

5),

mo

reli

kel

ysa

tisfi

edif

stru

ctu

rere

solv

ed(8

6%

ver

sus

5%

;p\

0.0

01

)

Pao

lin

iet

al.

[38]

(20

04

)R

CT

,A

T1

.E

L?

pla

ceb

o=

33

pat

ien

tsM

ean

age

49

yea

rs,

62

%m

en,a

llm

idp

ort

ion

,29

%b

ilat

eral

2,

6,

12

,2

4w

eek

s:p

ain

(sca

lefr

om

0to

4)

wit

hac

tiv

ity;

21

–6

1%

,V

AS

pai

nw

ith

ho

pp

ing;

29

–5

4%

(wit

hin

gro

up

sig

nifi

can

cen

ot

rep

ort

ed)

2,

6,

12

,2

4w

eek

s:2

.4–

2.8

9:

inan

kle

pla

nte

rflex

or

mea

nto

tal

wo

rk(s

ign

ifica

nce

no

tg

iven

)2

.E

L?

GT

N=

31

pat

ien

ts

Pet

erso

net

al.

[39

](2

00

7)

RC

T,

AT

1.

EL

=3

7p

atie

nts

Mea

nag

e4

3y

ears

,6

0%

men

,9

2%

acti

ve,

all

had

mid

po

rtio

nsy

mp

tom

s,b

ilat

eral

=1

1%

6,

12

,5

4w

eek

s:1

0–

16

%im

pro

vem

ent

inA

mer

ican

Ort

ho

pae

dic

Fo

ot

and

An

kle

Ass

essm

ent

sco

re,

20

–6

0%

;in

VA

Sp

ain

wit

hac

tiv

ity

(p\

0.0

01

)

12

wee

ks:

no

sig

nifi

can

tch

ang

ein

ten

do

nA

Pd

iam

eter

2.

Air

hee

lb

race

35

pat

ien

ts

3.

EL

and

Air

hee

lb

race

=2

8p

atie

nts

Pu

rdam

etal

[27]

(20

04

)C

CT

,P

T1

.E

L=

8p

atie

nts

Mea

nag

e2

5y

ears

,7

5%

men

,al

lac

tiv

e(d

ecli

ne

squ

atg

rou

po

lder

,m

ore

fem

ales

and

mo

reb

ilat

eral

inju

ries

bu

tn

ot

sig

nifi

can

t)

12

wee

ks:

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Sp

ain;

sig

nifi

can

tly

inth

eE

Lg

rou

po

nly

(62

%;

p\

0.0

5).

Mo

rere

turn

edto

pre

-in

jury

acti

vit

yin

EL

gro

up

(75

%v

ersu

s1

1%

;p

=0

.04

)

NA

2.

EL

wit

ho

ut

dec

lin

eb

oar

d=

9p

atie

nts

Ro

mer

o-

Ro

dri

gu

ezet

al.

[43

](2

01

1)

SC

,P

TF

lyw

hee

l=

10

pat

ien

ts,

iner

tial

load

ing

usi

ng

fly

wh

eel

dev

ice

Mea

nag

e2

5y

ears

,al

lac

tiv

em

en,5

0%

bil

ater

al6

,12

wee

ks:

86

%im

pro

vem

ent

inV

ISA

(p\

0.0

1),

60

%;

inV

AS

pai

n(p

\0

.01

)

6w

eek

s:ec

cen

tric

forc

e:

90

%(p

=0

.03

),co

nce

ntr

icre

ctu

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mo

ris

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G:

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%(p

=0

.03

),n

och

ang

ein

con

cen

tric

forc

e,ec

cen

tric

rect

us

fem

ori

sE

MG

and

bil

ater

alC

MJ

hei

gh

t

Ro

mp

eet

al.

[21]

(20

07

)R

CT

,A

T1

.E

L=

25

pat

ien

tsM

ean

age

=4

9y

ears

,4

0%

men

,3

2%

acti

ve,

all

mid

po

rtio

n,

all

un

ilat

eral

16

wee

ks:

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%im

pro

vem

ent

inV

ISA

-A(p

\0

.01

).N

oim

pro

vem

ent

inth

ew

ait-

and

-see

gro

up

.M

ore

pat

ien

tsco

mp

lete

lyre

cov

ered

or

mu

chb

ette

rin

the

EL

(60

%)

ver

sus

wai

tan

dse

eg

rou

p(2

4%

)[p

\0

.01

]

16

wee

ks:

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chan

ge

inA

Pd

iam

eter

2.

ES

WT

=2

5p

atie

nts

3.

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t-an

d-s

ee=

25

pat

ien

ts

Sh

alab

iet

al.

[45

](2

00

4)

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,A

TE

L=

25

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ien

tsM

ean

age

51

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%m

en,

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%ac

tiv

e,al

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adm

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ort

ion

sym

pto

ms,

32

%b

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12

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do

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SA

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4%

(p\

0.0

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intr

aten

din

ou

ssi

gn

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sig

nal

/no

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olu

me


Tab

le4

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ued

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dy

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r)D

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rven

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ns

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tici

pan

tch

arac

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stic

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ical

ou

tco

me

Mec

han

isti

co

utc

om

es

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ber

nag

elet

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](2

00

1)

RC

T,

AT

1.

Co

mb

ined

=2

2p

atie

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,ca

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ises

,b

alan

ce,

then

ecce

ntr

iclo

adin

g,

then

add

edsp

eed

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nag

e4

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ears

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7%

men

,al

lm

idp

ort

ion

and

acti

ve

(ex

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pat

ien

tin

gro

up

2),

41

%b

ilat

eral

12

,2

6w

eek

s:V

AS

wal

kin

g(4

0%

)an

dp

ain

wit

hp

alp

atio

n(2

9–

57

%);

inco

mb

ined

gro

up

on

ly(p

\0

.05

)

26

wee

ks:

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Sac

tiv

ity;

inb

oth

gro

up

s(5

7–

80

%),

also

;in

com

bin

edg

rou

pat

6w

eek

s(4

4%

)[p

\0

.05

].1

2m

on

ths:

com

bin

edg

rou

pm

ore

lik

ely

sati

sfied

(78

%v

ersu

s3

8%

;p\

0.0

5)

and

con

sid

ered

them

selv

esre

cov

ered

(60

%v

ersu

s3

8%

,p\

0.0

5),

no

sig

nifi

can

td

iffe

ren

cein

retu

rnto

pre

-in

jury

acti

vit

y(5

5%

com

bin

ed,

35

%ca

lfra

ise/

stre

tch

ing

)

6,

12

,2

6w

eek

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lfen

du

ran

ce:

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–3

0%

bo

thg

rou

ps,

no

gro

up

dif

fere

nce

s.1

2,

26

wee

ks:

:C

MJ

hei

gh

t7

–3

0%

bo

thg

rou

ps,

calf

rais

e/st

retc

hin

gg

rou

pal

so:

at6

wee

ks,

no

gro

up

dif

fere

nce

s.2

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OM

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%co

mb

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gro

up

on

ly.

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chan

ge

inD

Fat

any

tim

e

2.

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fra

ises

and

stre

tch

ing

=1

8p

atie

nts

Sil

ber

nag

elet

al.

[23

](2

00

7)

RC

T,

AT

1.

Co

mb

ined

=1

9p

atie

nts

,id

enti

cal

toS

ilb

ern

agel

20

01

bu

tad

ded

ho

pp

ing

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nag

e4

6y

ears

,5

3%

men

(mo

rew

om

eng

rou

p2

),al

lm

idp

ort

ion

and

acti

ve,

34

%b

ilat

eral

6,

12

,2

4,

52

wee

ks:

VIS

A-A

imp

rov

emen

tin

bo

thg

rou

ps

(p\

0.0

1,

up

to6

0%

com

bin

ed,

up

to4

9%

com

bin

ed?

spo

rt),

no

dif

fere

nce

bet

wee

nth

eg

rou

ps

6,

12

,2

6,

52

wee

ks:

:ec

cen

tric

-co

nce

ntr

icw

ork

20

–2

9%

(p\

0.0

5)

[no:

at1

2w

eek

sin

gro

up

1].

12

,2

6,

52

wee

ks:

:ec

cen

tric

-co

nce

ntr

icto

e-ra

ise

po

wer

17

–2

6%

gro

up

2o

nly

(p\

0.0

5)

[on

ly:

at6

wee

ks

ing

rou

p1

],n

och

ang

ein

con

cen

tric

toe-

rais

ep

ow

erin

eith

erg

rou

p.

26

wee

ks:

:d

rop

CM

Jh

eig

ht

11

%,:

ho

pq

uo

tien

t2

7%

,g

rou

p2

on

ly(p

\0

.05

).N

och

ang

ein

CM

Jh

eig

ht

inei

ther

gro

up

.6

,2

6w

eek

s:;

DF

RO

M5

–6

%,

gro

up

2o

nly

(p\

0.0

5)

2.

Co

mb

ined

?co

nti

nu

edsp

ort

=1

9p

atie

nts

Sil

ber

nag

elet

al.

[41

](2

00

7)

SC

,A

TC

om

bin

ed=

37

pat

ien

tsM

ean

age

46

yea

rs,

54

%m

en,

all

had

mid

po

rtio

nsy

mp

tom

s

12

mo

nth

s:5

9%

imp

rov

emen

tin

VIS

A-A

on

sym

pto

mat

icsi

de

(p\

0.0

5),

67

%cl

assi

fied

asfu

lly

reco

ver

ed(V

ISA

-AC

90

)

12

mo

nth

s:lo

wco

rrel

atio

nb

etw

een

VIS

A-A

sco

res

and

test

bat

tery

(r=

0.1

8;

p=

0.4

1)

(cal

fra

ise

end

ura

nce

,d

rop

CM

Jh

eig

ht,

ho

pp

ing

ply

om

etri

cq

uo

tien

t,co

nce

ntr

icto

e-ra

ise

po

wer

,ec

cen

tric

toe-

rais

ep

ow

er).

On

lyd

rop

CM

Jh

eig

ht

was

sig

nifi

can

tly

corr

elat

edw

ith

VIS

A-A

sco

res

(r=

0.1

78

;p

=0

.61

,p\

0.0

1).

Am

on

gth

e‘f

ull

yre

cov

ered

’p

atie

nts

,2

5%

had

C9

0%

of

un

affe

cted

sid

eo

nfu

nct

ion

alte

stb

atte

ry

P. Malliaras et al.

Tab

le4

con

tin

ued

Stu

dy

(yea

r)D

esig

nG

rou

ps,

inte

rven

tio

ns

Par

tici

pan

tch

arac

teri

stic

saC

lin

ical

ou

tco

me

Mec

han

isti

co

utc

om

es

Sil

ber

nag

elet

al.

[40

](2

01

1)

SC

,A

TC

om

bin

ed=

34

pat

ien

ts,

foll

ow

-u

po

fS

ilb

ern

agel

20

07

stu

dy

coh

ort

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nag

e5

1y

ears

,5

3%

men

,al

lac

tiv

ean

dh

adm

idp

ort

ion

sym

pto

ms

5y

ears

:fu

nct

ion

alev

alu

atio

nam

on

g1

3p

atie

nts

wh

ow

ere

asy

mp

tom

atic

,5

pat

ien

tsw

ho

had

con

tin

ued

sym

pto

ms

5y

ears

:d

efici

tb

etw

een

affe

cted

and

un

affe

cted

sid

e—as

ym

pto

mat

ics:

9%

for

ecce

ntr

ic-c

on

cen

tric

wo

rk(p

=0

.09

),1

4%

for

con

cen

tric

po

wer

(p=

0.0

4).

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defi

cit

for

ecce

ntr

ic-c

on

cen

tric

po

wer

,d

rop

CM

Jh

eig

ht,

ho

pq

uo

tien

t.C

on

tin

ued

sym

pto

mat

ics

had

an1

8%

defi

cit

for

con

cen

tric

po

wer

(p=

0.0

3)

Van

der

Pla

set

al.

[42

](2

01

2)

SC

,A

TE

L=

46

pat

ien

ts,

foll

ow

-up

of

de

Jon

ge

20

10

stu

dy

coh

ort

Mea

nag

e5

1y

ears

,9

1%

acti

ve,

all

had

mid

po

rtio

nsy

mp

tom

s,2

6%

bil

ater

al

5y

ears

:7

0%

imp

rov

emen

tin

VIS

A-A

fro

mb

asel

ine

(p\

0.0

01

),1

2%

imp

rov

emen

tin

VIS

A-A

fro

m1

yea

r(p

=0

.00

6)

5y

ears

:A

P;

7%

(p=

0.0

51

),D

op

ple

rp

rese

nt

59

%b

asel

ine

and

47

%at

foll

ow

-up

(p[

0.0

5).

VIS

A-A

chan

ge

and

at5

yea

rsw

asn

ot

asso

ciat

edw

ith

bas

elin

eD

op

ple

r.P

ain

pre

sen

cean

dV

ISA

-Aat

5y

ears

no

tco

rrel

ated

wit

hb

asel

ine

AP

dia

met

er

Vis

nes

etal

.[1

1](2

00

5)

RC

T,

PT

1.

EL

=1

3ac

tiv

eat

hle

tes

Mea

nag

e2

7y

ears

,6

5%

men

,v

oll

eyb

all

pla

yer

s,4

2%

bil

ater

al

12

,1

8w

eek

s:n

osi

gn

ifica

nt

chan

ge

inV

ISA

sco

res,

no

sig

nifi

can

td

iffe

ren

ceto

con

tro

lg

rou

p

12

wee

ks:

:b

ilat

eral

CM

Jh

eig

ht

(1.2

cm,

p=

0.0

46

)in

ET

gro

up

.S

Jh

eig

ht

(un

i-,

bil

ater

al),

CM

Jh

eig

ht

(un

ilat

eral

)n

och

ang

eei

ther

gro

up

2.

Co

ntr

ol

=1

6ac

tiv

eat

hle

tes

Yo

un

get

al.

[31]

(20

05

)R

CT

,P

T1

.E

L=

9ac

tiv

eat

hle

tes

Mea

nag

e2

7y

ears

,7

7%

men

,v

oll

eyb

all

pla

yer

s1

2m

on

ths:

mo

reli

kel

ycl

inic

ally

sig

nifi

can

tV

ISA

chan

ge

inE

Lg

rou

p(9

4%

ver

sus

41

%)

NA

2.

Sta

nis

han

dC

urw

in=

8ac

tiv

eat

hle

tes

AP

ante

rop

ost

erio

r,A

TA

chil

les

ten

do

n,

CC

Tco

ntr

oll

edtr

ial,

CL

con

cen

tric

load

ing

,C

MJ

cou

nte

rmo

vem

ent

jum

p,

CSA

cro

ss-s

ecti

on

alar

ea,

do

rsifl

exio

n,

EL

ecce

ntr

iclo

adin

g,

ESW

TE

xtr

aco

rpo

real

sho

ckw

ave

ther

apy

,E

MG

elec

tro

my

og

rap

hic

acti

vit

y,

GT

Ng

lyce

rol

tri-

nit

rate

,H

SRh

eav

ysl

ow

resi

stan

ce,

HP

hy

dro

xy

lysy

lp

irid

ino

lin

e,IE

Lis

ok

inet

icec

cen

tric

load

ing

,L

Ply

syl

py

rid

ino

lin

e,M

RI

mag

net

icre

son

ance

imag

ing

,M

VC

max

imal

vo

lun

tary

con

trac

tio

n,

NA

no

tap

pli

cab

le,

PF

pla

nte

rflex

ion

,P

Tp

atel

lar

ten

do

n,

RC

Tra

nd

om

ized

con

tro

lled

tria

l,R

OM

ran

ge

of

mo

tio

n,

RM

rep

etit

ion

max

imu

m,

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ng

leco

ho

rt,

SJsq

uat

jum

p,

US

ult

raso

un

dim

agin

g,

VA

Sv

isu

alan

alo

gu

esc

ore

,V

ISA

Vic

tori

anIn

stit

ute

of

Sp

ort

Ass

essm

ent,

VIS

A-A

VIS

A-

Ach

ille

sv

ersi

on

:,in

dic

ates

incr

ease

;;,

ind

icat

esd

ecre

ase

aM

ean

age,

gen

der

,u

ni-

ver

sus

bil

ater

al,

mid

po

rtio

nv

ersu

sin

sert

ion

(fo

rA

To

nly

)an

dac

tiv

ity

.A

llim

agin

gst

ud

ies

use

ult

raso

un

dex

cep

tfo

rS

hal

abi

etal

.[1

01]

and

Gar

din

etal

.[4

8]

(MR

I)


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 whensport is continued [23] (iv) improvement in clinical

outcomes is not associated with resolution in side-to-sidedeficits 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 followingStanish 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 thatimproved clinical outcomes are associated with

(i) decreased anteroposterior diameter [21, 25, 33, 39, 42];

(ii) a decrease in the proportion of tendons containingDoppler 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 twolow-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].


one low-quality study that improved clinical outcomesfollowing 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 improvedclinical outcomes are associated with (i) an increase in type

I collagen synthesis [49], but not associated with reduced

glutamate concentration [51]; (ii) reduced Achilles tendoncapillary 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 evidencefrom two high-quality studies, which showed that improved

clinical outcomes are associated with (i) increased knee

extensor torque [19]; (ii)increased leg press 1-repetitionmaximum (1RM) [18]; (iii) increased quadriceps muscle

CSA [19]. There is conflicting evidence from two high-

quality studies that improved clinical outcomes are notassociated 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 thatimproved 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 limitedevidence 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 onelow-quality study that there is no group difference in

change in knee flexor and extensor torque between Stanish

and Curwin and isotonic loading [29].


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 PropertyOutcomes

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 withreduced 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 arenot associated with change in tendon stiffness and modulus

[19].

3.3.2.2.2 HSR. There is moderate evidence from twohigh-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 andLP 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 highquality [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 whencompared with other loading programmes. There was

limited evidence from one study that patient satisfaction/

return to preinjury activity is greater following eccentriccompared with concentric loading in the Achilles tendon

[32]. This evidence should be interpreted with caution, as

the concentric group performed different exercises that arelikely 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 asmuch evidence for the Silbernagel-combined programme

as there is for the Alfredson eccentric programme when

comparing them to other loading programmes in Achillestendinopathy. The gradual progression from eccentric-

concentric to eccentric followed by faster loading may

benefit patients who are unable to start with an Alfredsoneccentric programme due to pain or calf weakness.

In the patellar tendon, there is conflicting evidence thateccentric 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 thegreater patient satisfaction. Good-quality evidence is

lacking for both Achilles and patellar tendinopathy, but

there is clearly benefit from loading programmes thatinvolve eccentric-concentric muscle actions.

Some studies investigated tendon loading prior or during

a competition phase. Young et al. [31] found that sloweccentric 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] foundeccentric decline squatting did not improve patellar tendon

VISA outcomes when performed during a volleyball sea-

son. Silbernagel et al. [23] found continued sport activitydid not compromise clinical outcomes at 12 months, as

long as sport was gradually introduced to ensure minimal

pain during and after loading. Continuing sport withrehabilitation 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 andSilbernagel-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 isalso limited evidence that quadriceps size increase is


similar following HSR and eccentric loading in the patellar

tendon [19]. Overall, Silbernagel and eccentric loading inthe 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 andhypertrophy (especially type II fibres) than concentric

loading [52], but not when the load is equalized [52],

suggesting load intensity rather than contraction type is thestimulus. 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 lessresultant 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 realizedvia 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 eccentriccontraction under load, as predicted by the force-velocity

curve [55, 57] (Fig. 2). For example, when a sprinter

increases running speed the hamstring muscle-tendonduring limb deceleration will increase. Therefore, clinical

eccentric loading among tendinopathy patients may not

lead to a greater change in neuromuscular outcomesbecause 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 associatedwith clinical improvement in patellar tendinopathy fol-

lowing eccentric [11, 18], and limited evidence following

flywheel loading [43], even though sport was continued inthese studies based on pain monitoring. A recent systematic

review found some evidence for increased vertical jump

performance in patellar tendon patients compared withasymptomatic cohorts, which may partly explain this

finding [58].

4.2.3 Do Side-to-Side Neuromuscular and JumpPerformance 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 thatperformance may need to be maintained with ongoing

loading.

4.2.4 Imaging, Structure and Biochemicals

The only evidence for change in imaging measures in theAchilles tendon is decreased intratendinous signal inten-

sity on magnetic resonance imaging (MRI) following

eccentric loading (moderate evidence) [45, 48]. Thisreview did not identify any evidence that tendon dimen-

sions (anteroposterior diameter, CSA) and the proportion

of tendons with Doppler signal change following Achilleseccentric loading, despite limited evidence for increased

collagen type 1 production. In the patellar tendon,

improved clinical outcomes were not associated withreduced 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. LO isometric length, PO maximumisometric tension, Vmax 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 concentrationand HP/LP ratio, indicative of collagen turnover [19]. This

suggests that HSR has

achilles and patellar tendinopathy loading programmes · conclusion there is little clinical or...

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