Effectiveness of Muscle Energy

Technique on Improving Hamstring

Extensibility in Healthy, Asymptomatic

Adults with Hamstring Tightness:

An Evidence-Based Review

Judy Pang, MS, DPT(c)

UCSF/SFSU Graduate Program in Physical Therapy

Clinical Problem

Muscle extensibility is an essential element of normal biomechanical functioning (Wassem et al., 2010)

The hamstring (HS) muscles are susceptible to decreased extensibility

Significance of Problem

Do you have tight HS?

Have you treated

someone with tight HS?

http://www.cartoonstock.com/directory/h/hamstrings_gifts.asp

Significance of Problem

Difficult to determine prevalence of HS tightness

Decreased HS extensibility is often associated with:

Hip and knee movement dysfunctions

Patellofemoral pain/patella tendinopathy

HS strains

Lumbosacral postural changes/ low back pain

Bakhtiary et al., 2011, Wassem et al., 2010, Ayala, 2011, and Shadmehr et al., 2009

Relevance to PT

Benefits of flexibility (Wassem et al., 2010)

Improved ROM, function, coordination and movement

Reduced injury risk and improved athletic performance

PTs utilize a variety of interventions to treat HS tightness (Bakhtiary

et al., 2011)

Static and ballistic stretching

Proprioceptive neuromuscular facilitation (PNF)

Eccentric training (ECC)

Muscle energy technique (MET)

Purpose

Primary

Examine current literature regarding the

effectiveness of MET on improving HS extensibility

in healthy, asymptomatic individuals with HS

tightness

Secondary

Compare the effectiveness of MET to no treatment

or an alternative treatment for improving HS

extensibility in healthy, asymptomatic individuals with

HS tightness

Definition: Hamstring shortness

Hamstring shortness

Lacking >15-30° of knee extension in popliteal angle test

Active Knee Extension: ICC=0.99 (Gajdosik and Lusin, 1983)

Passive Knee Extension: ICC=0.93 (Gnat et al., 2010)

Wassem et al., 2010, Shadmehr et al., 2009, Smith and Fryer, 2008 & Ballantyne et al., 2003,

http://nexusphysicaltherapy.com/a_hamstring.html

Definition: Muscle Energy Technique

A manual technique that involves A muscle, or group of muscles

Voluntarily contracted isometrically

Sub-maximal: ≤75% maximum voluntary isometric

contraction (MVIC)

Specific direction

Defined length of time

Mitchell & Mitchell, 1995

Application of MET

Stretch the muscle to a

palpated ‘barrier’

Produce sub-MVIC

Muscle relaxes; clinician

maintains stretch

Clinician ‘takes up the slack’

following relaxation

Muscle lengthened to new

barrier

Repeat process

Smith and Fryer, 2008

Theory Explanation Supported?

Neurological Reflex muscle relaxation

Biomechanical Viscoelastic changes

Sensory Tolerance to stretch

Theoretical Construct

The exact mechanism is still unclear

Magnusson et al., 1996, Ballantyne et al., 2003, Weppler et al., 2010, Folpp et al., 2006, Chaitow L, 2009

No

No

Yes

PNS: Gate Control

Theory of Pain

CNS: Activates

Brain Pain

Centers

Circulating

Biomarkers

Theoretical Construct: Sensory Theory

Decrease Pain

Muscle Energy

Technique

Increase Tolerance to Stretch

Increase HS Extensibility

Chaitow Leon, 2009

Gap in Literature

Limited research supporting and

validating the use of MET

No systematic review or meta-

analysis

Small sample sizes

High variability in MET

application parameters

Attempt to collect and pool

existing data

http://www.experienceproject.com/stories/Took-The-Do-You-Have-Gaps-In-Your-Knowledge-Quiz/1434705

Research Questions

Population Intervention Comparison Outcome

Healthy,

asymptomatic

persons with

short HS

Muscle

Energy

Technique

-No treatment

-Alternative

technique

-PKE

-AKE

Foreground

Primary

In healthy, asymptomatic persons with

short HS, how effective is MET at

improving HS extensibility?

Secondary

How does MET compare to no

treatment or other treatments at

improving HS extensibility in healthy,

asymptomatic persons with short HS?

Null Alternative

Application of MET on

the HS muscle will not

improve HS extensibility

in healthy,

asymptomatic persons

with short HS

Application of MET on the HS

muscle will improve HS

extensibility in healthy,

asymptomatic persons with

short HS

MET is not as effective

compared to no

treatment or an

alternative technique at

improving HS

extensibility

MET will be more effective

than no treatment or an

alternative technique at

improving HS extensibility

S

eco

nd

ary

P

rim

ary

Hypotheses

Expected Findings

At least 10 articles matching criteria

Reject both null hypotheses

Expect

MET to be effective at improving HS extensibility

MET is more effective compared to no treatment

and alternative treatments

Search Methods Data bases Searched:

Recursive search

Keywords:

“Muscle energy technique”

MET

Post-isometric relaxation

Active muscular relaxation

technique

Hamstring

Tightness

Flexibility

Shortness

Extensibility

Length

Last search date: 5.02.12

Search Methods

Inclusion criteria

MET to the HS muscles

Outcome measure: PKE and/or AKE

No restrictions on age or gender

Persons with short HS

Exclusion criteria

PNF

Non-English language articles

Hamstring injuries or lower extremity injuries

Neurological impairments

Articles identified

through database and

recursive search: (n=33)

Number of duplicates

removed: (n=5)

Articles screened: (n=28)

Articles excluded due

to irrelevance or to not

meeting following

inclusion criteria:

(n=24)

-Patient population

-Knee extension not an

outcome measure

-MET not performed

-If study directly used

PNF instead of MET

Articles selected for

inclusion in evidence

based review: (n=4)

Search Results

*A secondary reviewer confirmed that the four studies met the inclusion and exclusion criteria and were

appropriate for this review.

All studies

were RCTs,

level 1b

Study Characteristics

Abbreviations: PA:popliteal angle, N=number of participants, y.o.:years old, PKE: passive knee extension,

AKE: active knee extension

Author

HS

Criteria

(PA)

N

Age

(y.o)

Female

Male

Outcome

Time of

Measurement

(days)

Ballantyne

A et al.,

2003

Not

stated

40

18-45

Ave

23.4

22

18

PKE

1

Shadmehr

A et al.,

2008

30°

30

20-25

30

0

PKE

28

Smith M

and Fryer

G, 2009

15°

40

Ave

22.1

17

33

AKE

1

Waseem

M et al.,

2010

20°

40

18-25

0

40

AKE

5

Author MET Intervention Comparison Results

MVIC

(%)

Contraction

Time (sec)

Relaxation

Time (sec)

Ballantyne A et

al, 2003

75 5 3 Control MET

Shadmehr A et

al., 2008

50 10 10 Static,

passive

stretch

Both

Smith M and

Fryer G, 2009

40 2-3 10 Chaitow’s

MET

Both

Smith M and

Fryer G, 2009

40 30 10 Greenman’s

MET

Both

Waseem M et

al., 2010

75 5 3 Eccentric

Training with

theraBand

MET

40-

75% 2-30 sec 3-10 sec

Abbreviations: MVIC: maximum voluntary isometric contraction, MET: muscle energy technique

Study Characteristics

Statistical Analysis

Extracted means and standard deviations for knee extension ROM

Single group effect size

Two- group effect size

Each study weighted by inverse variance prior to pooling data

Calculate Q statistic to determine homogeneity: random vs. fixed model

Grand effect sizes and 95% CI were calculated

Forest Plot

Grand effect sizes converted to clinical units

-1 0 1 2 3 4 5 6 7

Shadmehr

et al.

Smith &

Fryer:

Chaitow

Smith &

Fryer:

Greenman

Waseem

et al.

Ballantyne

et al.

Grand

Effect Size

Effect Size (d)

Results:

Single Group

Effect Sizes Significant Q: Random effects model

Small <0.3

Moderate 0.3-0.8

Large >0.8

Jewell 2008

1.56 (0.58, 2.54)

STATISTICALLY

SIGNIFICANT!

Results:

Two-Group

Effect Sizes Non-significant Q: Fixed effects

model

-1 -0.5 0 0.5 1 1.5 2

Waseem et al.

Ballantyne et

al.

Shadmehr et al.

Grand Effect

Size

Effect Size (d)

Small <0.3

Moderate 0.3-0.8

Large >0.8

Jewell 2008

0.56 (0.18, 0.95)

STATISTICALLY

SIGNIFICANT!

Discussion

Null Alternative

Application of MET on the

HS muscle will not

improve HS extensibility

in healthy, asymptomatic

persons with short HS

Application of MET on the HS

muscle will improve HS

extensibility in healthy,

asymptomatic persons with short

HS

MET is not as effective

compared to no treatment

or an alternative

technique at improving

HS extensibility

MET will be more effective

than no treatment or an

alternative technique at

improving HS extensibility

S

eco

nd

ary

P

rim

ary

Discussion: Why is MET effective?

PNS: Gate

Theory

CNS: Activates

Brain Pain

Centers

Circulating

Biomarkers

Decrease Pain

Muscle Energy

Technique

Increase Tolerance to Stretch

Increase HS Extensibility

Response Bias

Chaitow Leon, 2009

Discussion: Effect of Dosing

100

110

120

130

140

150

160

170

180

Shadmehr et

al.

Smith & Fryer:

Chaitow

Smith & Fryer:

Greenman

Waseem et al. Ballantyne et

al.

Study

Kn

ee E

xte

nsio

n (

deg

rees)

Pre-MET

Post-MET

-1 0 1 2 3 4 5 6 7

Shadmehr

et al.

Smith &

Fryer:

Chaitow

Smith &

Fryer:

Greenman

Waseem

et al.

Ballantyne

et al.

Grand

Effect Size

Time of measurement (days)

28 1 1 5 1

5X

Discussion: Harm and Cost

Harm & Risk

No studies indicated any

harm or adverse effect

May potentially

strain/tear HS or cause

neural symptoms

Cost

Not addressed in literature

No materials needed

Time efficient

Direct PT care

Cost of PT education and

possibly continuing education

Clinical Units Conversion

Commonly assume 5° measurement error and a 10°

Minimally Clinically Important Difference (Weijer et al., 2003)

ES (95% CI) Clinical Units Significant?

Single Group 1.56 (0.58, 2.54)

Two-Group 0.56 (0.18, 0.95)

Abbreviations: ES: effect size, CI: confidence interval

No

No

2.2° -9.7°

1.4° -7.1°

Clinical Implication

Statistically significant but not clinically significant

Dependent on type of population

Longer treatment duration

MET should be trialed

Statistically significant

Trends toward 10 ° MCID Low cost

Money

Time Low risk of harm

Recommended

Parameters

MVIC: 40-75%

Contraction Time: 2-3 sec

Relaxation time: 3-10 sec

*Based on qualitative analysis

Limitations Only one primary researcher

English language

Limited # of databases, narrow search terms

Limited # of studies

Small sample sizes

Heterogeneity in qualitative aspects of study designs

Lack of standardization for MET parameters

Subjective MVIC

No studies had muscle-tendon stiffness data

Real versus apparent muscle extensibility

Directions for Further Research

Larger sample size

Standardize MET protocol

More representative population

Age

History of HS injury

Abnormal fibrous tissue & cross-linkages

Longer term of treatment

Muscle-tendon stiffness data

http://scholasticadministrator.typepad.com/.a/6a00e54f8c25c9883401676355388a970b-popup

Conclusions • MET is a statistically

significant intervention at improving HS extensibility

• MET is more effective than no treatment or alternative treatments

• Not clinically significant

• Further research needed to provide standardization and clear guidance for the use of MET in patients with HS injuries

-1 0 1 2 3

Single Group

Grand Effect

Size

Two-Group

Grand Effect

Size

0.56 (0.18, 0.95)

1.56 (0.58, 2.54)

Effect Size (d)

Acknowledgements

Betty J. Smoot, PT, DPTSc

Erica A. Pitsch, PT, MPT, DPT

Diane Allen, PT, PhD

Kristine Amii, MS, DPT(c)

Aaron Chung, MS, DPT (c)

UCSF/SFSU MS-DPT class of 2012

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