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Core stability and low back rehabilitation

• Supportive texts and readings• Stuart McGill, PhD - Professor University of Waterloo -

Internationally recognized expert in spine function and injury prevention and rehabilitation– Low Back Disorders 2007 (Human Kinetics)

• Outline• Introduction• Anatomy and Neutral Pelvis• Assessment • Conditioning• Prescription guidelines

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Introduction• Low back and abdominal exercises are prescribed primarily for

– rehabilitation of injured low back– Prevention of injury– As a component of fitness training programs

• Goal is to stress both damaged and healthy supporting tissue to promote tissue repair – while avoiding further excessive loading that can exacerbate existing

structural weakness– ACSM chapter discusses the science of understanding loading forces

and revisits some common practices in abdominal and low back training

• Most effective – train motor control system to activate spine stabilizers– Progress to endurance training– Finally enhance strength and flexibility

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Core Stability• Stabilizing muscles - act to support muscle action

by providing rigid base of support for movement • Core stability provided by muscles in the torso

connecting the spine, rib cage and pelvis• When standing the pelvis and lumbar spine are

oriented for maximal stability fig 1• Goal of training is to maintain this “neutral spine”

orientation throughout dynamic movement– Lumbosacral angle ~ 41 degrees

• Stabilizing exercise are ones that groove motor patterns and ensure a stable spine during activity

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Anatomy of the Core• No one muscle is the most important muscle for stability - varies

with movement pattern– For athletes a conflict of stability and rhythmic contraction/relaxation of

forced breathing exists• Abdominal Group

– In addition to stabilization each muscle group contributes to trunk movement

• Transverse abdominus– Forced expulsion

• Internal obliques– Lateral flexion, rotation to same side and flexion of trunk

• External obliques– Lateral flexion of trunk to same side, rotation to opposite side and flexion

of trunk• Rectus abdominus

– Flexion of trunk

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Anatomy of the core• Back Muscles• Erector Spinae

– Trunk extension• Multifidus

– Lateral flexion, extension and hyperextension of the spine

• Quadratus lumborum– Highly involved in lumbar spine stabilization - largely

isometric• Latissimus dorsi

– Role as spine stabilizer enhanced by pulling to chest in lat pull down exercise

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Assessment• Muscular endurance closely related to spinal stability and

risk of low back pain– Balance of muscular endurance among torso flexors, extensors and

lateral musculature is most important in reducing injury risk• All tests evaluated on time to failure and compared to

normative data for overall time and ratios between test scores

• Lateral musculature test– Test performed on both sides of the body– Lying in full side bridge, legs extended, top foot in front– subject supported on one elbow and feet while lifting hips off the

floor to create a straight line over their body length – Uninvolved arm placed across the chest with hand on opposite

shoulder– Failure occurs when person loses the straight-back posture and hip

returns to ground

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Assessment (cont)• Flexor endurance test

– Begins with person in a sit-up posture with the back resting against a jig angled at 60 degrees

– Knees and hips flexed at 90 degrees– Arms folded across chest– Hands on opposite shoulders– Toes are secured by examiner or toe straps– Test begins by pulling support back ten centimeters– Failure occurs when subject falls back and touches jig

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Assessment (cont)• Back extensors test

– Upper body cantilevered over the end of test bench - hands across chest

– Time to failure - drop from horizontal– CPAFLA - similar test described in detail

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Interpreting scores• Tests just described have reliability coefficients of .98 or

greater • Normative data is presented in Table 12.1 of Mcgill - Low

back disorders (2002)– Data gathered from healthy men (n=92) and women (n=137) with a

mean age of 21• Interpreting absolute endurance is secondary to interpreting

the relationship among the three muscle groups (flexors, lateral, and extensors.)

• The following discrepancies in ratios of time to failure suggest unbalanced endurance

• R / L side bridge > .05 away from unity• Flexion / Extension > 1.0• Either Side bridge / extension > .75

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Training for core stability and low back health

• Variable effectiveness has been found for training and rehabilitation programs for low back in different studies

• Variability may be due to prescription of inappropriate exercises caused by a lack of understanding of tissue loading

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Training for core stability and low back health

• S McGill evaluated exercises with respect to tissue loading injury criteria, not solely for maximized muscle activity

• General Role for exercise in low back health– Stimulates hypertrophy– Slows (reverses?) degenerative conditions– Enhances nutritional benefits to spine– More effective than surgery, bed rest or flexibility training

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Exercise Training• Focus on progressive

exercise that emphasizes muscle contraction with the spine in neutral position– Spine posture determines

interplay between ligament and muscle forces

– Extensor muscles activated in neutral position reducing load on spine

– Fully flexed spine fails at about 20-40% lower compressive load than with neutral position

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Relative loads on the thirdlumbar disk for living subjects

Upright standing depicted as 100%

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The line of gravity shifts further ventrally during relaxed unsupported sitting (B) as the pelvis is tilted backward and the lumbar lordosis flattens (this creates a longer lever arm).When sitting erect (C) the pelvic backward tilt is reduced and the lever arm shortens (still longer than when standing (A).

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Exercise Training

• Several exercises are required to train all of the muscles of the lumbar torso– Individual fitness level, training goals, history of spinal injury

should influence prescription• Exercises should avoid loading spine throughout ROM

post injury• Elite athletes may achieve higher performance levels by

using full ROM in exercises

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Abdominal Bracing and Neutral Spine

• Teaching Abdominal bracing– co-contraction of abdominal wall muscles for spinal

stability• 1. Demonstrate joint stability in peripheral joint

through flexor/extensor co-contraction – have subject palpate demonstrator then themselves

• 2. Identify core musculature - cough with hand above hips - palpate abdominal wall during contraction

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Abdominal Bracing and Neutral Spine

• Teaching Neutral spine• 1. lying on back, knees bent - place fingers between lumbar

spine and floor – hyper lordosis - increase gap from floor– hypo lordosis - flatten back onto fingers– Can utilize blood pressure cuff and observe rise and fall in pressure

with same movements.• 2. Put subject through lifting exercise or simulated work

situations– Place long stick across lumbar, subject must maintain contact across

lumbar, avoiding trunk flexion throughout motion.

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Core Exercises• All endurance exercises should last up to seven to

eight seconds• Progression in program should come from adding

more repetitions rather than adding duration• Utilize normative data from assessments to

develop client goals • Curl ups reduce spinal compression compared to

sit ups and leg raises• Press heel sit-ups - recent evidence advanced them

as beneficial • However, active hamstrings actually stimulate

psoas activity and higher compressive penalty on spine

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Abdominal Exercises• Partial Curl ups

– Focus on rectus abdominus• Distinct upper and lower rectus abdominus do not exist in most people • training can be accomplished with a single exercise

– Retain neutral spine, do not flatten back to floor– Beginner

• Supine with hands supporting lumbar spine• One leg bent at 90 degrees• Lift thoracic and cervical spine as one unit, no cervical motion should occur

(chin poking or chin tucking)• Leave elbows on floor, contract rectus and lift head and shoulders off the

floor– Intermediate

• lift elbows slightly off floor– Advanced

• place fingers lightly on forehead• Head and neck must move as unit, maintaining rigid block position on

thoracic spine

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Abdominal Exercises• Horizontal Side bridge

– Challenge lateral obliques and quadratus lumborum– Low lumbar compressive load– Variable demand on rectus and others with progressive stages of exercise– Remedial

• Standing 45 degrees and leaning to wall• Lying on floor and raising legs• Utilize back extension bench at 45 degrees and support from side

– Beginner• Lateral support on knees bent at 90 degrees and elbow, maintain torso straight• Top arm across chest with hand on shoulder

– Intermediate• Legs straight with top foot in front• Variation - incorporate longitudinal rolling of the torso forward and backward

– Advanced• Transfer from one elbow to the other while maintaining abdominal bracing

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Extensor exercises• Traditional extensor exercises - high spinal loads due to ext applied loads from

weights of resistance machines• Fig 13.9 bird dog

– Remedial• Raise a hand or knee slightly off floor

– Beginner• Single leg raise on hands and knees

– Intermediate• Simultaneous contra-lateral arm raise with leg raise - increases extensor

challenge• Hold six to eight seconds when parallel

– Advanced• Do not rest by placing the and and knee on the floor after each holding repetition• Sweep the floor with hand and return out

– Common errors include hiking hips and not achieving neutral spine• exercise lying prone and lifting legs is contraindicated for anyone at risk for low

back injury due to hyperextension

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Advanced exercises• athletes can incorporate forced breathing cycles

into all exercises• Labile surfaces - exercise ball, wobble boards

– Increase co-contraction, doubling spinal load in many exercises

– Fig 14.1 and 14.2 (Mcgill - 2002)• Not recommended until subject has achieved

spinal stability and sufficiently restored load-bearing capacity– Can delay improvements by causing exacerbating spine

loads if adopted early in rehabilitative program

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Advanced exercises• Ball Exercises

– Table top spine– Forward ball roll– Total body flexion– Curl up– Push up

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Advanced exercises• Squat and Power cleans

– Great for developing power• Form is more important than weight being lifted as

injury is likely– Europeans, practice technique for years before adding

weight• Recommend beginning from elevated position if

not a competitive weight lifter• McGill recommends athletes use medicine ball in

the same motion pattern to avoid high stress of lifting bar from ground

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Aerobic exercises• Evidence supporting positive role of aerobic

exercise in reducing incidence of low back injury and in the treatment of low back patients

• Walking– Low levels of support tissue load– Mild, prolonged activation of supporting musculature

• Study comparing elderly engaged in a variety of lifelong activities– Runners - no detrimental changes in low back health– Weightlifters and soccer players - more disc

degeneration and bulges

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Flexibility• Flexibility of the spine has yet to be shown to improve

outcomes of low back exercise programs or reduce risk of future injury in healthy populations

• Flexibility of hip has shown to be important • Avoiding end of ROM during athletic and daily activities

can reduce risk for several types of injuries• Limit training to unloaded flexion/extension• Fig 13.4 cat stretch - full ROM recommended only for

athletes who have never had a back injury• Hip and knee flexibility should be performed with neutral

spine– Fig 13.5 and 13.6

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Exercise Prescription• Recommendations• Low back exercise most beneficial if performed daily• No pain, no gain does not apply• Inclusion of general exercise (aerobic) is most effective• Unwise to perform full ROM of spine early in the morning -

Disc more hydrated in morning • Emphasis should be endurance over strength, for low back

health• Training objectives must be identified individually in terms

of – injury risk, optimizing health or maximizing athletic performance

• May take 3 months to observe inc function and pain reduction