Shoulder strength ratios – stability, rom and muscle balance.

ASCA Conference 2010

Copyright ‐ Dr Mark McKean USC 1

Dr Mark McKean PhD

SHOULDER STRENGTH RATIOSSTABILITY, 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



GORILLAS

Forward Shoulders

Rounded shoulders

Round backs

EIFFEL TOWERS

Low Shoulders

SQUARE SHOULDERS ARMS



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 (Kibler1998)

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 ycreating 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)



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)



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 2004Schmidt‐Wiethoff

Baseball 400 1030 2000 Donatelli

Kayak 430 880 2009 McKean

Normal 610 850 2004Schmidt‐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)



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

[email protected]

Shoulder strength ratios – stability, rom and muscle balance.

Health & Medicine

Transcript of Shoulder strength ratios – stability, rom and muscle balance.