Title: Muscular Stretching: Facts and Fallacies
1Muscular Stretching Facts and Fallacies
- C. S. Nasin, MD
- Adapted from A. Buetler, MD
- Primary Care Sports Medicine
2Learning Objectives
- Review the history and cultural importance of
muscular stretching - Review the current literature on stretching
- Improved flexibility
- Flexibility as a risk factor
- Prevention of sports injuries
- Review recent hypotheses to explain the mixed EBM
finding
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4History of Stretching
- 500-700 B. C. origin of gymnastics--as it was
believed that this would facilitate unity of mind
and body. - 5000 B.C. The primitive origins of martial arts
5History of Stretching
- Yoga sanskrit to unite
- A series of spiritual practices arising gt 5,000
years ago. - Hatha yoga developed in the 15th century
utilized asanas (body postures) to seek
self-enlightenment - 16.5 million Americans now practice yoga, a 3
billion dollar fitness industry
6Athletic Culture
- Stretching has become embedded in sport folklore
as the universal strategy for injury prevention - -Thacker S., et al Med Sci Sports Exerc. 2004.
7Does stretching improve flexibility?
8Stretching short and long-term changes
- Short term
- Redistribution of liquid and polysaccaharides
within the collagen matrixes of the tendon
-McNair et al. Med Sci Sports Exerc 2001
- Duration of increased flexibility 60-90 minutes
DePino et al J. Athletic Training 1982 Moller
et al Arch of Phys Med Rehab 1985
9Stretching short and long-term changes
- Long term
- Structural changes within the collagen (changes
in the viscoelastic properties) - Kubo et al J.
Physiology 2002 - Increased flexibility after an extensive program
may last for several weeks -McCue et al Res Q
1953 Zebas et al Curr Sel Res, 1985
10Does flexibility decrease our risk of injury?
11Defining Flexibility StretchingSafety in
Middle Ground
- Epidemiology of Injuries Associated with Physical
Training in Young Men in the Army - Jones et al - Med Sci Sports Exer, 1993
- 303 Army Basic Trainees
- Baseline Fitness Assessment
- Questionnaire and Fitness Testing
- Final Assessment
- Final Army PT Test
- Tracked all physician visits for 12 weeks
12Defining Flexibility StretchingSafety in
Middle Ground
Risk Factors for Lower Extremity Musculoskeletal
Injuries (Adjusted Ratios)
95 CI greater than 1.0
- Risk Factor Odds Ratio
- Flexibility
- Q1 (lowest 20) 3.6
- Q2 1.7
- Q3 (mid 20) 1.0
- Q4 1.9
- Q5 (highest 20) 3.3
- Training Unit
- Low Mileage 1.0
- High Mileage 1.6
- Risk Factor Odds Ratio
- Age gt 24 4.3
- Smoking 1.9
- Previous Injury
- No Injury 1.0
- Non-Sprain Injury 0.6
- Ankle Sprain 1.7
- Physical Activity
- Above Average 1.0
- At or below Avg 2.2
- Epidemiology of Injuries Associated with Physical
Training in Young Men in the Army Jones et al
13Defining Flexibility StretchingSafety in
Middle Ground
Least Flexible ? Mid ? Most Flexible
14Does stretching prevent injury?
15CLINICAL SCIENCES Clinical Investigations The
Impact of Stretching on Sports Injury Risk A
Systematic Review of the Literature STEPHEN B.
THACKER1, JULIE GILCHRIST2, DONNA F. STROUP3, and
C. DEXTER KIMSEY, JR.3 1Epidemiology Program
Office, 2National Center for Injury Prevention
and Control, and 3National Center for
Chronic Disease Prevention and Health Promotion,
Centers for Disease Control and Prevention,
Atlanta, GA
361 Articles reviewed Included -Only RCT or
cohort studies that included stretching -Excluded
-Studies that lacked controls -Studies where
stretching could not be independently
assessed -Studies that did not include subjects
in sporting activities
Medicine Science in Sports Exercise 2004
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17A prospective study on the management of shin
splints.Andrish T, et alJ. Bone Joint Surg
1974 (56) 1697-1700.
- 2777 male Navy midshipmen randomized into one of
five groups - Heel pad (4.4)
- Heel stretch (4.0)
- Pad stretch (3.0)
- Graduated run (6.0)
- Control (3.0)
18High-School football injuries effects of a
post-halftime warm-up and stretching
routine.Bixler B, Jones RFamily Practice
Residency Journal
- 5 Pennsylvania HS football teams 128 games
- 3/5 teams performed 3min half-time
warm-up/stretch - No difference in total 3rd Quarter injuries
intervention group with less sprains/strains.
19Effects of ankle dorsiflexion range and
pre-exercise calf muscle stretching on injury
risk in army recruitsPope R, et alAust J
Physiother 1998 44(3) 165-172.
- 1093 male army recruits in 12 platoons 12 wk
basic training - Two 20s calf stretches before rigorous exercise
(Intervention) - Two 20s tricep stretchs before rigorous exercise
(Control) - 23 vs 25 lower extremity injuries (p0.76)
20Effects of a static stretching program on the
incidence of lower extremity musculotendinous
strainsCross K, Worrell TJ of Athletic
Training, 1999 34(1) 11-14.
- 195 Div III football players 1994/1995 seasons
- 1994- no stretching
- 1995- static stretching program prior to
conditioning (hamstrings, gastrocs, quads,
adductors) - No difference in overall injuries significant
decrease in lower ext. musculotendinous injuries
(21 vs 43)
21Increasing hamstring flexibility decreases lower
extremity overuse injuries in military basic
trainees.Hartig D, Henderson JAm. J. Sports Med
1999 (27)
- 298 Army recruits _at_ Fort Benning 2 basic trainee
companies - Intervention group TID static hamstring
stretches - Results
- Intervention 25 LE overuse injuries (17)
- Control 43 LE overuse injuries (29)
22A randomized trial of pre-exericse stretching for
prevention of lower-limb injuryPope R, et alMed
Sci in Sport Exerc. 2000 (32)
- 1543 male australian army recruits from 39
training platoons - Intervention 20s supervised stretches of 6 major
LE muscle groups before each training exercise - Results
- Intervention 158 LE injuries (21)
- Control 175 LE injuries (22)
23Meta-Analysis Results Stretching and Primary
Prevention of Athletic injuries
- Thacker et al (MSSE 2004)
- Review of 361 articles 6 included
- No association
- Herbert Gabriel (BMJ 2002)
- 5 studies included
- No association between stretching and injury or
muscle soreness. - Yeung Yeung (Cochrane Review 2001)
- Review of 118 articles 12 included
- No association
24Difficulties in Stretch Studies
- Timing of stretching
- Type of stretching
- Intrinsic RF for injuries
- Extrinsic RF for injuries
- Gender
- Differences between sports/positions
I pity the fool who does this research
25Stretch-Shortening Cycles (SSC) and Muscle Tendon
Unit Compliance Another Piece of the Puzzle
- Stretch-Shortening cycles (SSC) is a natural
muscle function where a concentric action is
preceded by an eccentric action, and this leads
to a higher concentric torque value in healthy
persons. -
- -High SSC Sports (i.e. bouncing and jumping
activities) soccer, football, rugby -
- -Low SSC Sports jogging, swimming, cycling
Stretching and Injury Prevention An Obscure
Relationship -Witvrouw E, Mahieu N, Danneels L,
and McNair P Sports Medicine 2004 34 (7)
443-449.
26High SSC Sports Requires storage and release of
elastic energy
-
- High Compliance tendon more energy can be
absorbed by the tendon tissue, reducing trauma to
muscle.
Increased energy Absorption
Decreased Work
27Low SSC Sports benefit with low compliance
tendon for efficient energy transfer
-
- Low Compliant tendon forces will be
transferred to the contractile apparatus and
little will be absorbed by the tendon -
Decreased energy Absorption
Increased Work
28The effect of sports specific training on
reducing the incidence of hamstring injuries in
professional Australian Rules Football
players.Verrall GM - Br J Sports Med -
01-JUN-2005 39(6) 363-8
- Single ARF team followed
- Intervention group Hamstring stretches with
muscle fatigue sports specific drills, and ?high
intensity aerobic cross-training - Significant reduction in Hamstring strains
missed games (plt0.05)
29A survey of flexibility training protocols and
hamstring strains in professional football clubs
in England. - Dadebo B - Br J Sports Med -
01-AUG-2004 38(4) 388-94
- Questionnaire data from 30 professional English
teams collected 1998/99 - Stretching was the most important training factor
assoc. with HSRs (not statistically significant)
30Incidence, risk, and prevention of hamstring
muscle injuries in professional rugby union. -
Brooks JH - Am J Sports Med - 01-AUG-2006 34(8)
1297-306
- Nordic hamstring strengthening and HS stretching
regimens decreased rates and severity of HSRs.
31So what are the answers?
- Stretching DOES increase flexibility
- Flexibility IS a risk factor for injury at the
extremes - There is not sufficient evidence to endorse or
discontinue routine stretching before or after
exercise to prevent injury among competitive or
recreational athletes.-Thacker et al 2004 - May be of particular importance in high SSC sports
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33Questions??