Core stability and low back rehabilitation

1. 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

2. 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

3. 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

5. 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

7. 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

9. 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

11. 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

13. 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

14. 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

16. 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

17. 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

18. 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

19. Relative loads on the third lumbar disk for living subjects Upright standing depicted as 100%

20. 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).

21. 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

22. 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

24. 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.

26. 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

28. 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

29. 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

30. 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

32. 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

34. Advanced exercises • Ball Exercises • Table top spine • Forward ball roll • Total body flexion • Curl up • Push up

40. 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

41. 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

42. 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

44. 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