Understanding the shoulder

1. ASCA Conference 2010
Copyright ‐ Dr Mark McKean USC 1
Dr Mark McKean PhD
SHOULDER STRENGTH RATIOS
STABILITY, ROM AND MUSCLE BALANCE.
SESSION SUMMARY
This session will cover
 Shoulder strength & flexibility research
 The relative ratios for shoulder strength & flexibility.
 Key issues for program design
CLAVICLE POSITION SCAPULA
RIBCAGE POOR THORACIC CURVE
Soldiers and hunchbacks
 You must try and correct curve first
 Scapula must sit flat on curve

2. ASCA Conference 2010
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GORILLAS
 Forward Shoulders
 Rounded shoulders
 Round backs
EIFFEL TOWERS
 Low Shoulders
SQUARE SHOULDERS ARMS

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Copyright ‐ Dr Mark McKean USC 3
2008
RESEARCH WHAT WE KNOWRESEARCH – WHAT WE KNOW
SCAPULA POSITION/STABILITY
 Scapula stability exercises and thoracic curve correction
should be done before rotator cuff exercises (Kibler
1998)
 Ideal scapula position yet to be determined but it is not
in its inner range of lower traps, and “down and back” is
not an appropriate command (Mottram 1997)
 Trapezius and serratus anterior most important stabilisers
acting on scapula thoracic joint (Mottram 1997)
 The external rotator muscles synchronise with the deltoids y
creating a force couple necessary for normal, unrestricted
motion (Kolber 2009).
 The deltoid provides dynamic stability with the arm in the
scapular plane and only decreased the stability of the
shoulder with the arm in the coronal plane. (Lee 2002)
 The infraspinatus, subscapularis, and latissimus dorsi act
as stabilisers during flexion;
 the subscapularis acts as a stabiliser during external the subscapularis acts as a stabiliser during external
rotation and the supraspinatus during extension.
(Kronberg 1990)

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APPLICATION
 Exercise routines that emphasize the deltoids and
neglect the rotator cuff may create an imbalance of the
deltoid–rotator cuff force couple, leading to altered
l di i i d AROM dmuscle coordination, restricted AROM, and
impingement of the shoulder complex during arm
elevation (Kolber 2009)
 Increases in rotator cuff muscle forces tended to
improve stability whereas increases in deltoid or
pectoralis major muscle forces decrease stability
(Labrioloa 2005)
 The mid and posterior heads of deltoid should be
strengthened vigorously in anterior shoulder
instability...., because they provide more stability
i hi h i f d l hgenerating higher compressive force and lower shear
force... (lee 2002)
IMBALANCES
 Overhead athletes with impingement symptoms
demonstrated strength deficits and muscular imbalance
in the scapular muscles compared with uninjured
hl (C l 2005)athletes. (Cools 2005)
 Significant difference in awareness of scapula position
between dominant and non‐dominant shoulders. (Boyar
2007)
SCAPULA STABILITY SUMMARY
A few key things to remember
 Ideal position
 Muscles involved in force couples
 Muscles you must always include exercises for in
strength programs
PULL:PUSH RATIO
 Rugby players – bench press to pull ups 1:1 (Baker 2004)
 Kayak paddlers – bench press to pull ups (McKean 2009)
 females ‐ 1:1.47,
 males 1:1.29
 Normal population – pull:push ratio using dynamometer
1:1.12 (Peebles 2003)
RELATIVE STRENGTH RATIOS
 If use a base exercise ‐ 1RM Pull up = 100% (kayakers –
McKean 2009)
 8 RM Shoulder press ‐ Deltoid – 18%
 8 RM External rotation ‐ External rotators – 9%
 8 RM Bent over trap raise ‐ Traps – 6%
 Suggested rotator cuff ratio of internal to external
strength is approx 1 to 1.3 ‐ 1.6. (Codine 1997,
Niederbracht 2008, Barlow 2002, Hughes 1999)

5. ASCA Conference 2010
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 Flexion:extension – 1.26‐2.22 (depending on angle
isometric measure taken 30‐60‐90 degrees flexed ‐
Hughes 1999)
 Abduction:adduction – 1.53‐2.63 (depending on angle
isometric measure taken 30‐60‐90 degrees abducted ‐
Hughes 1999)
 Both ratios above increased to a higher ratio with age.
i.e. Both extension and adduction movements became
proportionally weaker
STRENGTH SUMMARY
A few key issues to remember
 Upper body muscle balance not solely based on ratios
but also posture and movementbut also posture and movement
 Every sport may have a different relative ratios but try
and keep Traps and Rotator cuff relatively strong for
improved shoulder stability
SHOULDER FLEXIBILITY
Population IR ER Year Author
Based on position of assessment done at
900 abduction
Tennis 440 890 2004
Schmidt‐
Wiethoff
Baseball 400 1030 2000 Donatelli
Kayak 430 880 2009 McKean
Normal 610 850 2004
Schmidt‐
Wiethoff
Ideal 700 900 2005 Kendall
OTHER NOTESOTHER NOTES
 Isometric strength was significantly lower for the
Scapula Protracted position compared with the
Scapula Neutral position and Scapula retracted
position (Smith 2002)
 By increasing the eccentric external total exercise
capacity you potentially decrease shoulder rotator
muscle imbalances and the risk for shoulder injuries
(Niederbracht 2008)
 Bodybuilders showed an overall loss of shoulder rotation
ROM (1660 vs. 1880) and a significantly decreased
internal rotation ROM (‐110) compared with the control
(B l 2002)group. (Barlow 2002)
 Bodybuilders were significantly weaker in lower
trapezius strength when expressed as a percentage of
body weight. (Barlow 2002)

6. ASCA Conference 2010
Copyright ‐ Dr Mark McKean USC 6
FLEXIBILITY SUMMARY
A few key issues to remember
 Ideal range of movements vary
 Strength training and some upper body sports reduce
range of motion at the shoulder which may lead to
injury
KEY ISSUES FOR PROGRAM DESIGNKEY ISSUES FOR PROGRAM DESIGN
POSTURE
 Ensure thoracic curve close to ideal before you address
shoulder related strength problems
 Must reinforce correct thoracic curve at all times for all Must reinforce correct thoracic curve at all times for all
upper exercises
 Need to negate the associated and exaggerated
movement of thoracic hyperextension when pulling
 Check ROM for select postures e.g. Does ROM at
shoulder allow them to press vertically without thoracic
posture changing
PATTERN
 Control/ROM must occur before strength
 Practice makes permanent – not always perfect
 Simplify pattern until it can be controlled and perfected
 Poor movement patterns are the main cause of most
muscle balance related issues – i.e. Trying to go too
heavy, too quickly, too dynamic, too early before good
patterns established
PROPRIOCEPTION
 Teach athletes to “feel” the exercise, the movement, the
stress, and the response of the body
 Unstable surface training is often applied too quickly Unstable surface training is often applied too quickly
before athletes can “feel” a posture or pattern.
 Once complicated by increased proprioceptive demand,
most athletes lose “control” of the pattern and are
unable to develop proper force output
DR MARK MCKEAN PHDDR MARK MCKEAN PHD
 Post Doctoral Research Fellow
 University of Sunshine Coast ‐ Fitness Research
 mmckean@usc.edu.au