Core Training: Evidence Translating to Better Performance and Injury Prevention

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1. Which of the following core muscles are typically trained with repeated spinal flexion despite their primary function as stabilizers? a. external obliques b. rectus abdominus c. quadratus lumborum

2. Which of the following core muscles did the author mention had evidence in assisting hip function while strongman training? a. quadratus lumborum b. rectus abdominis c. multifidus

3. When interpreting the biomechanics of a new client, which of the following is one of the most simple way to first assess them? a. Observe the way they walk in and sit down. b. Utilize movement screening tests to determine where to start. c. Perform provocative tests to identify motor patterns that are tolerated.

4. If an individual has chronic back pain, they might be utilizing their______as hip extensors rather than their ______. a. gluteal muscles; erector spinae b. hamstrings; gluteal muscles c. erector spinae; hamstrings

5. The author discussed that the rectus abdominis muscles were not meant to stretch, rather they are meant to function as a spring; instead of flexing the muscles, they are meant to stiffen and thus transfer energy generated at the hips. Which of the following core exercise would be most appropriate to train this movement pattern? a. Stability ball pike b. Stability ball curl up c. Stability ball ‘stir the pot’

6. In order to build endurance while avoiding cramping from oxygen starvation, the author recommends isometric exercises of what duration? a. 10 seconds b. 15 seconds c. 20 seconds

7. Which of the following repetitive motions did the author cite as the damaging mechanism for spinal disc herniations? a. Lumbar flexion b. Thoracic rotation c. Cervical extension

8. Those with back pain typically utilize poor mechanics for walking, sitting, standing, and lifting. What is this irregular movement pattern defined as in the article? a. “Quad drivers” b. “Glute amnesia” c. “Hamstring restlessness”

9. The article discusses how the “Big 3” exercises (modified curl-up, side bridge, and quadruped bird-dog) were used as a successful injury prevention program in which of the following sports? a. Co-ed swimming b. Men’s basketball c. Women’s gymnastics

10. What time of day are spinal discs most swollen from osmotic superhydration? a. Morning b. Afternoon c. Evening

33 KEY WORDS: core; exercise; back pain bending of the spinalinjury discs is mechanism aexample potent of (10,61). misdirected practicemonly Another occurs com- when some trainers have their clients pull in their‘‘activate abdominals their to transverse abdominis’’ to enhance stability. First,target this the major does stabilizers of not because the spine studies thatshow measure that stability theizers most are task important specific. stabil- For example, sometimes the quadratus lumborum is most important, yet many trainers neglect this muscleond, (19). drawing Sec- thereduces abdominals stability inward (57). Third,on evidence transverse abdominisactivation disturbances shows may that some people occur with specific in types ofdisorders, back but thatbances these same are distur- notabdominis because unique they occur in tomuscles many transverse (11,59). Peopleactivate are this muscle unable in to isolation beyond very low levels ofit contraction is because designed tooblique muscle activate for with athletic tasks internal (18).would It appear that trainerson who this muscle focus are misdirected. Other evidence showsmakes how the the core capable. rest For of example, the in body our more work Strength and Conditioning Journal | www.nsca-lift.org progressions for their clients. Theis core composed of themuscles lumbar of spine, the back the extensors, abdominal and quadratusrum. wall, lumbo- Also the includedmuscles, are namely, the multijoint latissimuspsoas dorsi and thatlinking pass it to the throughand pelvis, legs, the arms. shoulders, biomechanical Given core, synergy with the the pelvis, the anatomic gluteal and musclessidered may to also be be essentialprimary con- power components generators as (the synergy of these componentswhere is (36)). outlined else- The core musculatureently functions than the differ- limbcore musculature muscles in often that cocontract,the stiffening torso such thatsynergists—examples all in a muscles wide become varietytraining of and athleticvided in activities Refs. (2,3,5,13,14,15,19,20,53,55). are pro- Thus, training the core effectivelytraining means itmuscles. differently thanEvidence the and common practice are limb not always consistent in themunity. training For example, com- some believe that repeated spine flexion is a good method to train the flexorsinis (the and rectus abdom- the abdominalingly, wall). these Interest- muscles arethis rarely way used because in used they to are brace moreThus, while they often stopping more often motion. actthan as stabilizers flexors. Furthermore, repeated

National Strength and Conditioning Association Ó for optimalinjury performance prevention. and This article he well-trained core is essential

THIS REVIEW ARTICLE RECOG- NIZES THE UNIQUE FUNCTIONTHE OF CORE MUSCULATURE. IN MANY REAL LIFE ACTIVITIES, THESE MUSCLES ACT TOTHE STIFFEN TORSO AND FUNCTION PRIMARILY TO PREVENT MOTION. THIS IS A FUNDAMENTALLYFERENT DIF- FUNCTION FROM THOSE MUSCLES OF THE LIMBS,CREATE WHICH MOTION. BY STIFFENING THE TORSO, POWER GENERATED AT THE HIPS ISMORE TRANSMITTED EFFECTIVELY BY THE CORE. RECOGNIZING THIS UNIQUENESS, IMPLICATIONS FOR EXERCISE PROGRAM DESIGN ARE DIS- CUSSED USING PROGRESSIONS BEGINNING WITH CORRECTIVE AND THERAPEUTIC EXERCISES THROUGH STABILITY/MOBILITY, ENDURANCE, STRENGTH AND POWER STAGES, TO ASSISTPERSONAL THE TRAINER WITH A BROAD SPECTRUM OF CLIENTS. introduces several elements relatedthe to core todesigning assist personal trainers the in most appropriate Copyright T INTRODUCTION

Prevention SUMMARY Performance and Injury Stuart McGill, PhD Spine Biomechanics, Department ofWaterloo, Kinesiology, Ontario, Faculty Canada of Applied Health Sciences, University of Waterloo, Translating to Better Core Training: Evidence

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quantifying the tasks of strongman Thoughts are provided here for exer- swollen from the osmotic superhydra- training, we documented how the core cise professionals who deal with issues tion of the disc that occurs with bed assisted hip function to allow the related to the assessment and design of rest, has been proven very effective competitors to accomplish tasks that therapeutic exercise for the core. Core with this type of client (60). Further- they did not have the hip strength to training is of interest given the preva- more, typically, when this client bends perform (53). Specifically, the quad- lence of back pain among clients. Core to pick up a weight, they flex the spine ratus lumborum assisted in pelvis training is associated with spine stabil- adding to the cumulative trauma. This elevation to allow the swing leg to ity and instability that results from back often continues without correction make a step. This was the first evidence disorders. Evidence from the back from the trainer. This is a missed oppor- suggesting that a strong core allows disorders’ literature shows that poor tunity. Realize that the spine discs only strength to radiate out peripherally to movement patterns can lead to back have so many numbers of bends before more distant regions of the body. disorders. In this way, trainers should they damage (10). Keep the bends for Similarly, in training, our recent work consider the quality of movement essential tasks such as tying shoes (58) demonstrated how an individual patterns in all clients and by default rather than using them up in training. can only bench press half of their body should consider beginning any exercise Many lifestyle and occupational exam- weight when standing—otherwise they program with corrective exercises. ples have been provided elsewhere (28) would push themselves over. While Many trainers follow a ‘‘recipe’’ for to guide the elimination of the cause of laying, bench press performance was assessment, corrective exercise, or per- a client’s back troubles; the trainer will primarily governed by the chest and formance training. Using this generic find that half of their initial effective- shoulder musculature, whereas stand- approach ensures ‘‘average’’ results— ness will be because of preventing the ing press performance was governed some clients will improve and get cause (i.e., a flawed movement pattern). by core strength, particularly one-arm better, but many will fail simply This need not be so complicated. Con- presses. Thus, the limiting factor in because the approach was above or sider the client who stands slouched standing press ability was core strength. below the optimum level necessary to where the back muscles are chronically contracted to the point of chronic The core, more often than not, func- address the deficit. The program and muscle pain. The family doctor typically tions to prevent motion rather than approach principles introduced here prescribes muscle relaxants, which fail to initiating it, which is contrary to the are based on principles intended to relax the muscle. The trainer addresses approaches that many trainers employ assist development of elite corrective the postural cause and corrects standing in designing exercise for their clients. exercise and training specialists. to effectively silence the muscles and Good technique in most sporting, and remove the associated crushing load daily living tasks demands that power CONSIDER THE CAUSES OF from the spine (Figure 1) (32). be generated at the hips and trans- BACK DISORDERS mitted through a stiffened core (37). Here is a disturbing fact: many of the BUILDING THE SCIENTIFIC Pushing, pulling, lifting, carrying, and back pain patients I see have been FOUNDATION torsional exertions are enhanced using exacerbated by poor training programs Myths and controversies regarding this basic technique of hip power because the mechanism of injury was spine function and injury mechanisms generation but are compromised when unknowingly incorporated. The first are common. Consider ‘‘the cause’’ of the spine bends causing what is often step in any exercise progression is to back troubles, specifically the common referred to as ‘‘energy leaks.’’ Interest- remove the cause of pain or potential perception regarding common injury ingly, these task classifications greatly pain, namely, the perturbed motion pathways in which the back is injured assist the organization of program and motor patterns. For example, the from an ‘‘event.’’ Generally, statistics design (think of building exercises to flexion intolerant back is very common are compiled from epidemiological fulfill a push, pull, lift, carry, and a in today’s society (i.e., pain is produced approaches, which ignore the large torsional buttressing task rather than after repeated or prolonged back flex- role of cumulative trauma. Compensa- specific isolationist exercises for the ion). Giving this type of client stretches tion board data are often used, how- abdominals, back extensors, latissimus such as pulling the knees to the chest ever, and they ask clinicians to fill out dorsi, and the like). may give the perception of relief reports and name the ‘‘event’’ that As a contribution to this special issue, (through the stimulation of erector caused the ‘‘injury.’’ For example, ‘‘Mr I thought about how best to assist spinae muscle stretch receptors), but X lifted and twisted at the time that the increasing the competency of trainers. this approach only guarantees more injury occurred.’’ Kinesiologists and But after writing 2 textbooks (25,35) pain and stiffness the following day trainers know that twisting is different based on our hundreds of scientific because the underlying tissues sustain from generating twisting torque, but publications, I feel as though I have more cumulative damage. very few of the individuals filling out already said what is necessary and Eliminating spine flexion, particularly the reports will know. So, was it important in a cohesive story. in the morning when the discs are twisting torque that caused the injury?

34 VOLUME 32 | NUMBER 3 | JUNE 2010 Figure 1. (a) Poor standing posture causes constant spine load and chronic contracture of the erector spinae muscles causing muscular pain. (b) One approach for correction is to externally rotate the arms about the shoulders (steering the thumbs out). (c) Correcting the posture with chin and shoulder retraction reduces the chronic muscle contraction reducing pain and building training capacity.

Or, was it being twisted that caused the treatment. Avoiding this specific direc- mechanics that increase back loads. injury? Furthermore, despite the injury/ tional cause will lead to optimal thera- Many of them have stronger backs incident reporting system geared to the peutic exercise design together with but are less endurable than matched reporting of the ‘‘event’’ associated elimination of activities in the patient’s asymptomatic controls (47). They tend with the ‘‘injury,’’ very few back injuries daily routine identified as replicating to have more motion in their backs and occur this way. the cause. less motion and load in their hips. A common aberrant motor pattern is Evidence of the process of disc herni- Many training programs have the known as ‘‘gluteal amnesia’’ (27), which ation provides a proof of principle. For objectives of strengthening muscle may be both a common consequence example, the damaging mechanism and increasing spine range of motion. of back troubles and possibly a cause of leading to herniation, or prolapse, is This is problematic for some because them as well. The general principle repeated lumbar flexion requiring only those who have more motion in their that joint pain causes inhibition of the very modest concomitant compressive backs have a greater risk of having extensors and chronic facilitation of the loads (10). This trauma accumulates future back troubles (56). Strength with little indication to the future flexors to the point of ‘‘tightness’’ may, or may not, help a particular appears to be true with hip or back patient. With repeated flexion cycles, individual because strength without the annulus breaches layer by layer pain. Obviously, for this category of control and endurance to repeatedly client, exercises to enhance the in- with progressive delamination of the execute perfect form increases risk. layers (61). This allows gradual accu- tegration of the gluteal muscles will Interestingly, the differences between enhance back function while also mulation of nucleus material between many ‘‘troubled backs’’ (the chronic the delaminated layers. The location of sparing knees. Hip flexor mobility is back with recurrent episodes) and the annulus breaches can be predicted also needed (but special technique is matched asymptomatic controls per- by the direction of the bend. Specifi- needed to separately target psoas from forming the same jobs have been cally, a left posterior lateral disc bulge iliacus) (Figure 2) (38). Optimal back shown to be variables other than back will more likely result if the spine is exercise therapy results from the strength or mobility. Rather deficits in flexed with some additional right identification of these clients with motion and motor patterns have been lateral bend (1). Subsequent twisting perturbed patterns followed by specific documented as being more critical and leads circumferential rents in the corrective exercise—this precedes all annulus that tends to make McKenzie thus should be targets for therapeutic other exercise progressions. extension approaches for these clients exercise. useless or even exacerbating (23). This For example, people with troubled THE SCIENCE OF CORE STABILITY is critical information for the trainer, backs use their backs more. Generally, Effective core/spine stabilization both in terms of prevention and in they walk, sit, stand, and lift using approaches must begin with a solid

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techniques are described (38). Finally, some provocative tests, such as a shear test, will help reveal which classifica- tion of client is best suited for a stabilization approach (17). It is also interesting to consider the studies that have quantified training devices, which claim to enhance spine/core stability. For example, Moreside et al. (54) quantified stability when using the ‘‘Bodyblade’’ (Mad Dogg Athletics, Venice, CA), which is a flexible foil that is shaken at a resonant frequency. As with virtually all other tools, the technique determines the actual stability achieved. Poor body blade technique can actually reduce stability, whereas good technique, where the core is locked into an isometric contraction to control motion, enhances core stability. The role of the trainer is to be aware of this science, its implication on technique, and devote their attention to exercise form in the client. Figure 2. Lunging with the arm directed overhead helps to differentiate and target psoas from iliacus during hip flexor stretching. Hip extensor patterns are TOLERANCE AND CAPACITY simultaneously trained on the opposite side of the body. When this exercise Suppose a trainer wants to include is performed as walking steps, holding the posture for 2 seconds and pulsing the arm upward through the core, then taking a step and a lifting pattern to challenge the repeating, it becomes a facilitator and a good ‘‘warm-up’’ exercise. posterior components of the core. They are wondering if a squat with a weighted bar would be better than understanding of what stability is. a single muscle generally does not the birddog exercise. The choice is From a spine perspective, it has little enhance stability but creates patterns assisted by determining the tolerance to do with the ability to balance on that when quantified result in less and capacity of the individual to ensure a gym ball. This is simply the ability stability (20). It is impossible to train that a given exercise dosage is matched to maintain the body in balance, which muscles such as transverse abdominis to the client. Each individual has is important but does not address the or multifidus in isolation—people can- a loading tolerance which, when ex- unstable spine. In fact, in many in- not activate just these muscles. Do not ceeded, will cause pain and ultimately stances, the unstable spine is also perform abdominal hollowing techni- tissue damage. For example, a client flexion intolerant and with associated ques because it reduces the potential may tolerate a ‘‘birddog’’ extension intolerance to compression. Sitting on energy of the column causing it to fail posture but not a ‘‘superman’’ exten- an exercise ball and performing move- at lower applied loads (39). Interest- sion over a gym ball, which imposes ment exercises increases spine com- ingly, a recent clinical trial (22) com- twice the compressive load on the pression to a flexed spine (52). This pared the efficacy of many of the lumbar spine. For a more highly retards progress—it is generally a poor exercises quantified and published in trained person with a higher tolerance choice of back exercise until quite late Physical Therapy (24), with the same may find ‘‘supermans’’ very appropri- in a therapeutic progression. True exercises combined with specific trans- ate. A person’s capacity is the cumula- spine stability is achieved with ‘‘bal- verse abdominis isolation (hollowing tive work that he or she can perform anced’’ stiffening from the entire and the like). Adding the specific before pain or troubles begin. musculature, including the rectus ab- transverse abdominis training reduced For example, someone who can only dominis and the abdominal wall; efficacy. Instead, the abdominal brace walk 20 m before pain sets in has a low quadratus lumborum; latissimus dorsi; (contracting all abdominal muscles) capacity. This kind of person will not and the back extensors of longissimus, enhances stability. Target contraction benefit from therapeutic exercise that is iliocostalis, and multifidus. Focusing on levels for bracing and training performed 3 times per week; instead,

36 VOLUME 32 | NUMBER 3 | JUNE 2010 he or she has a better chance with 3 motions, postures, and loads. All in- 4. Perform movement screens and short sessions per day. Corrected formation is used to formulate the tests—Are there perturbed postural, walking in 3 short sessions per day, exercise progression plan starting with motion, and motor patterns? Do never exceeding the current tolerance corrective exercise and the starting they move well in daily activities and capacity, is an alternate approach dosage of tolerable therapeutic exer- such as getting out of a chair or up to building capacity. Typically, clients cise. This process concludes with off the floor? If not, the trainer will progress to 1 session per day as functional screens and tests that were should recognize corrective squat, their pain-free capacity grows and then chosen based on information obtained and lunge training is needed before be tolerant of a session with their in the preceding process—the assess- any loaded resistance progressions. trainers. ment process is well documented (29). 5. If the clinical picture is complex and These results are used to substantiate beyond your comfort zone, develop INTERPRETING CLIENT some speculation as to the existence of a referral relationship with a compe- PRESENTATION perturbed motion and motor patterns tent corrective exercise specialist. Our approach to client assessment and for considering exercise choice and This is reciprocal and will serve you incorporates a strong biomechanical rates of subsequent exercise progression. well with more clients in the future. foundation and blends expertise from various disciplines. First, an impression Interpreting client presentation AN EXAMPLE OF A PROVOCATIVE TEST THAT IS HELPFUL is formed from the first meeting of the Specific exercise programs for a client client, their sitting posture, how they with back pain are derived from the Provocative testing is a potent tool in rise from the chair, their initial gait following process (it is assumed that the assessment of back problems and pattern, and so on. Then, a history is appropriate medical screening has is easily performed. A wide variety of taken looking for possible candidate transpired): provocation tests together with some injury mechanisms and perceived pain 1. Observe everything, starting with corrective techniques are in a DVD exacerbators and relievers. Observation the client rising from a chair. (see Ref. (34)) because the expertise continues during some basic motion 2. History—link injury mechanisms, gained by viewing the technique can- patterns as the evaluation process pain mechanisms with specific ac- not be obtained from written text. proceeds delving further into the tivities, and past exercise regimens. Figure 3 (31) illustrates an example of mechanics and nature of the symp- Of course, if ‘‘red flags’’ appear, provocative testing for compressive load toms. Then, provocative tests are make the appropriate referral. tolerance. This posture-modulated tol- performed to identify motion and 3. Perform provocative tests—what erance test provides powerful informa- motor patterns that are tolerated. loads, postures, and motions exac- tion and can serve as a guide to avoid Specifically, we include a range of erbate, what relieve? damaging/exacerbating activity, and it also helps to design appropriate therapy. More practical information can be gleaned from simply asking whether a client has better and worse days in relation to pain. Even though it seems straightforward, it cannot be stressed enough that if there are indeed better and worse days, it means that some activities help and others hurt. Find out what they are and eliminate the exacerbating elements. For example, if prolonged sitting is not tolerated, avoidance of flexion by using a lumbar support will help, together with organizing tasks to eliminate prolonged sitting. This is known as ‘‘spine hy- giene’’ and will build more capacity for Figure 3. An example of provocative testing. The patient compresses the spine by the client to work with you. Specific grabbing the side edges of the seat and pulling up. When doing this with exercises designed to combat the an upright back (a), the torso is stiffened with muscle activity. The test is cumulative stresses of sitting should then repeated in a slouched posture (b); discomfort in this position as then be prescribed. compared with an upright back shows a lower tolerance when the spine is flexed (and a flexion intolerant patient). This reveals where the spine REDUCING THE RISK OF INJURY tolerance is highest, and therefore, a posture to begin therapeutic exercise No exercise professional can be (i.e., no spine flexion). fully successful without removing the

Strength and Conditioning Journal | www.nsca-lift.org 37 Core Training for Better Performance

Figure 4. (a) Curl-up over a gym ball motions stresses the discs, mimics a potent disc injury mechanism, and unwisely uses pain-free training capacity. (b) The ‘‘stir the pot’’ exercise spares the painful discs of motion and builds abdominal athleticism. movement flaws that are the cause of LINKING ANATOMY WITH common training approach of curling back troubles in clients throughout the FUNCTION the torso over a gym ball that replicates day. Recommendations such as ‘‘when Consider the usual and popular ap- the injury mechanics while not creat- lifting, bend the knees and keep the proach to train the abdominal wall ing the athleticism that enhances back straight’’ rarely address the real muscles by performing sit-ups or curl- performance. This is a rather poor issue, despite their popularity. Few ups over a gym ball for example. But choice of exercise for most situations. patients are able to use this strategy consider the rectus abdominis where Yet many clients will expect that a gym in their jobs; furthermore, this is often the contractile components are inter- ball be used. Disguise your intentions not the best strategy. For example, the rupted with transverse tendons giving with these clients and retain the gym ‘‘golfers lift’’ is much more joint con- the ‘‘6 pack’’ look. The muscle is not ball, but change the exercise from a serving for repeated lifting of light loads designed for optimal length change but spine compromising curl-up to a plank from the floor. Here, one leg is raised rather to function as a spring. Why where the elbows are placed on the ball. behind, the torso tilts forward about a have these transverse tendons in rectus Now, perform a ‘‘stir the pot’’ motion flexed hip of the stance leg forming a abdominis? The reason is that when to enhance the torso/abdominal spring fulcrum. No spine or knee bending the abdominals contract, ‘‘hoop and spare the spine—this is often a much occurs. Another example illustrates the stresses’’ are formed by the oblique superior exercise for most people (see poor choice of movement strategies for muscles that would split the rectus Figure 4) (41). a particular task. For example, observe apart (26). In addition to the spring-like the client who transitions to laying on architecture of the muscle, consider DESIGNING STAGED CORE the floor by using a deep squat—this how it is used. People rarely flex the rib EXERCISE—BIOMECHANICS AND CLINICAL PRACTICE overloads their back. Squatting may be cage to the pelvis shortening the rectus Exercise progression is a staged pro- appropriate for getting off a toilet or in sport or everyday activity. Rather cess. Several sources are available chair but not necessarily for dropping they stiffen the wall and load the hips (30,40) that expand on the many to the floor. Instead a lunge that does or shoulders—if this is performed considerations and techniques to hone not bend the spinal discs may be a rapidly such as in a throw or move- clinical skills at each stage some of much more appropriate choice. Again, ment direction change, the rectus which are listed below.: this builds capacity for them to ac- functions as an elastic storage and complish more in their training session recovery device. When lifting weights, Stages of progressive exercise design: with you (see Ref. (30) for full explana- it stiffens to efficiently transmit the 1. Corrective and therapeutic exercise tion and evidence for spine sparing power generated at the hips through 2. Groove appropriate and perfect guidelines). Although it is not the the torso. Those individuals who do motion and motor patterns expertise of this author, ‘‘core stability’’ actively flex the torso (think of cricket 3. Build whole-body and joint stability training has been shown to be effective bowlers and gymnasts) are the ones (mobility at some joints such as the for both preventing and rehabilitating who suffer with high rates of spine hips and stability through the lum- shoulders (21) and knees (16,55). joint damage and pain. Now, revisit the bar/core region)

38 VOLUME 32 | NUMBER 3 | JUNE 2010 4. Increase endurance muscle reintegration helps to unload relatively low levels of contraction. For occupational/athletic clients: the back. Another critical concept for This is an endurance and motor 5. Build strength this stage of exercise design is that control challenge—not a strength chal- 6. Develop speed, power, and agility technique ‘‘details’’ are important. It is lenge. For many clients wanting to The first stage of designing the appro- not a matter of client performing an accomplish tasks of daily living pain priate corrective exercise emanates exercise, but it is a matter of the client free, this is sufficient. In the preceding from the identification of any per- performing the exercise with perfec- progressions, of course, strength is turbed motion and motor patterns. tion. Exercise form, subtle maneuvers enhanced as are specific patterns, such Every exercise is considered within to eliminate pain, pacing, duration, and as the ability to squat, push/pull, lunge, the working diagnostic hypothesis other coconsiderations are all ex- and so on. But strength is not specif- such that the first time the exercise is tremely important (51). The next stage ically trained because this requires performed, it is considered a provoca- in the progressive algorithm is to overload and elevated risk—this is tion test. If it is tolerated, the client encode movement and motor patterns reserved for performance training. proceeds. If it is not tolerated, the to ensure stability. Stability is consid- Many people, whether they have technique is reexamined and adjusted ered at 2 levels—both joint stability (in athletic objectives (such as wanting to and/or a more tolerable variation is this case spine/core stability) and play golf) or have demanding occupa- tried—see Ref. (51) for some examples whole-body stability. Quantification tions will fall into this category. where technique adjustments with of stability proves that these 2 objec- On the other hand, many clients stabilization exercise make them toler- tives are fundamentally different and confuse health objectives (minimizing ate much more challenge but without need 2 different exercise approaches. pain, developing joint sparing strate- pain. Examples of corrective exercise Our observation is that the 2 types of gies) with performance objectives are introduced here, although many stability are often confused in the (which require risk) and compromise are provided in Ref. (33). clinic/gym. Variations of our ‘‘Big 3’’ their progress with specific strength For example, gluteal muscle activation stabilization exercises (modified curl- training too early in the progression. retraining based primarily on the up, side bridge, and quadruped bird- Many exercises typically prescribed to original work of Janda has been honed dog) have been quantified and selected patients with low back pain are done so in our laboratory (Figure 5). This for their ability to ensure sufficient without the trainer having knowledge cannot be accomplished with tradi- spine stability and optimal motor of the spine load and associated muscle tional squat training (37). Chronic back patterns; they spare the spine of many activation levels. For this reason, we pain tends to inhibit the gluteal injury mechanisms and pain exacerba- have quantified exercises in this way muscles as hip extensors, and as a result, tors and are designed to build muscle (see Ref. (2,9,19,20)) to allow evidence- clients create hip extension using the endurance (see Figures 6–9) (49). based decisions when planning optimal hamstrings as a substituting pattern. Then, specific muscle group endurance exercise progressions. Consider devel- Subsequent back extension overacti- is enhanced. Spine stability requires oping progressions with some exer- vating the spine extensors creates un- that the musculature be cocontracted cises shown in Figures 10 and 11 necessary crushing loads. Gluteal for substantial durations but at (14,43).

Figure 5. Chronic back pain tends to cause people to use their hamstring muscles, instead of their gluteals to extend the hip. This changes patterns that increase spine load when squatting. Performing the back bridge, squeezing the gluteal muscles, and eliminating hamstrings helps to establish gluteal dominance during hip extension. Clinical cues are presented in McGill (37)—one is shown here as the trainer palpates the hamstrings, and if they are active, the client is cued to push the feet with knee extension and externally rotate the hips to ensure gluteal dominance.

Strength and Conditioning Journal | www.nsca-lift.org 39 Core Training for Better Performance

Figure 6. The ‘‘Big 3’’ stabilization exercises selected to create muscle patterns that ensure stability in a spine sparing way include the curl-up (poor form with too much spine flexion resulting in disc stress is shown in (a)) (better form shown in (b)). Although we have quantified many variations and progressions, there are several cues for correct form. For example, during the curl-up, try and remove any motion from the lumbar spine and the cervical spine. Progression included prebracing of the abdominal wall, elevating the elbows off the floor, and breathing, to name a few.

CAVEATS FOR THERAPEUTIC/ bigger initial gains in progress to- For example Durall et al. (12) docu- CORRECTIVE EXERCISE ward a pain-free back (see Ref. (42)). mented how training the ﬂexors, lateral 1. Keep the duration of isometric 3. Maintain impeccable form to en- musculature, and extensors of the core exercises under 10 seconds and hance available strength and main- with the Big 3 in the preseason for build endurance with repetitions tain the spine in its strongest (most 10 weeks prevented any new back pain (reps), not by increasing the dura- tolerable) posture. incidents and controlled the pain in tion of the holds. Near infrared those with a history of pain in a spectroscopy of the muscles showed CORE EXERCISE AS AN INJURY population of competitive collegiate that this was the way to build PREVENTION PROGRAM gymnasts. Gymnasts form a high-risk endurance without the muscles The exercises that form the ‘‘Big 3’’ group for back pain/disorders. In- cramping from oxygen starvation noted in the previous section have terestingly, similar exercises have and acid buildup (48). been used by many occupational and been shown to prevent knee injuries 2. Use the Russian descending pyra- sporting groups as part of an injury in female intercollegiate basketball mid to design sets and reps to make prevention program. players (16).

Figure 7. The beginner’s side bridge (a) is held for sets of 10-second contractions before more challenging progressions are attempted (b–d). Challenge is added by bridging from the feet and adding more mass to the bridge with arm placement.

40 VOLUME 32 | NUMBER 3 | JUNE 2010 An interesting example is provided with speed training. Many train speed by using resistance exercise for strength gain. But speed technique, when measured, also usually requires superior rates of relaxation. This ap- parent paradox can be exemplified this way. Consider the golf swing. The initiation of the downswing involves some muscle contraction but too much actually slows the swing. Speed comes from compliance and relaxation. At the instant just before ball contact, the farthest ball hitters in the world then undergo a full-body contraction that creates superstiffness throughout the Figure 8. The superman is a common extensor exercise but imposes double the entire linkage (45). Then, just as compressive load on a spine, which is hyperextended compared with the much more tolerable birddog exercise. The capacity to train the superman quickly the stiffening contraction is exercise is greatly compromised because pain is usually developed before released to allow compliance, speed in high levels of training can be achieved. Thus, it is rarely a good choice of the swing follow through. This same exercise. cyclic interplay between relaxation for speed and contraction for stiffness is TRAINING FOR PERFORMANCE (force 3 velocity) development in the measured in the best sprinters in the Training the back for performance (for spine is usually very risky. Instead, world, the best strikers and kickers in either athletic or occupational applica- power is developed about the should- mixed martial arts, the best lifters, tion) requires different approaches and ers and hips to both increase perfor- and so on. Thus, the rate of muscle objectives than training to fulfill re- mance and to minimize risk to the contraction is only important when habilitation objectives. Some of the spine and related tissues. Specifically, if the muscle can be released just as techniques developed in our work with the force in the spine/core is high (e.g., quickly—only a few in the world are world-class athletes are beyond the deadlifting), then the spine velocity able to do this. scope of this article and have been (i.e., bending to create muscle length These examples show why traditional detailed extensively elsewhere (35). change) must be low. If the spine strength training is usually a detriment These include the progressions from velocity is high (e.g., golf), then the to performance. Techniques of ‘‘super- establishing motor control patterns muscle force must be low (particularly stiffness’’ used by strength athletes are once the appropriate corrective exer- when the spine is deviated). This is important to understand when being cise was performed, through stability, why the great golfers ‘‘pulse’’ when the mindful of the lower functioning client endurance, strength, speed, power, and spine is traveling through the neutral who may be able to grasp some of agility. A note is needed here: power range just before ball contact. these concepts and, for the first time,

Figure 9. During the birddog exercise, making a ﬁst and cocontracting the arm and shoulder is a progression that enhances the contraction levels in the upper erector spinae (a). This is a better exercise than the superman because the spine loads are lower; the muscle contraction level can be similar using the ‘‘squares’’ technique (b), and the spine is neutral, not hyperextended that lowers the load tolerance.

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Figure 10. There are many progressions of exercises to stiffen and balance the anterior chain in a spine sparing way such as a staggered hand push-up (a) and the rollout (b). perhaps be able to rise from the toilet Eight essential components of the abdominal wall formed by the unassisted. In my consulting, I am often superstiffness internal and external obliques and asked ‘‘How do you design a training 1. Use rapid contraction, then relaxation transverse abdominis, highlighting program for a gymnast or wrester’’ of muscle. Speed results from relaxa- the need to contract them together who must produce high force with tion for speed but also stiffness in in a bracing pattern (15). a deviated spine posture? There are some body regions (e.g., core) to but- 4. Direct neuronal overflow. Strength several potential strategies, and the tress the limb joints to initiate motion is enhanced at one joint by con- choice depends on the body type, or enhance impact (of a golf club, tractions at other joints—martial injury history, current fitness level, hockey stick, fist, and the like) (50). artists call this ‘‘eliminating the soft and fitness goals of the athlete (to 2. Tune the muscles. Storage and re- spots.’’ Professional strongmen use name a few). Sometimes, it is necessary covery of elastic energy in the mus- this to buttress weaker joints using to avoid the injury mechanism (de- cles require optimal stiffness, which core strength (53). viated spine posture) in training and is tuned by the activation level. 5. Eliminate energy leaks. Leaks are save the ‘‘bending’’ for the competition. In the core, this is about 25% of caused when weaker joints are In this way, rigorous training can reach maximum voluntary contraction forced into eccentric contraction higher levels without injury. An exam- for many activities (4,8,5). by stronger joints. For example, ple of this approach can be found with 3. Enhance muscular binding and when jumping or changing running cricket bowlers in Australia who have weaving. When several muscles direction, the spine bending when reduced injury rates and maintained contract together, they form a com- the hip musculature rapidly con- performance by limiting the number of posite structure where the total tracts forms a loss of propulsion. bowling reps but still train other stiffness is higher than the sum of The analogy ‘‘you can push a stone activities. These newest concepts are the individual contributing muscles but you cannot push a rope’’ exem- compiled (40). (6). This is particularly important in plifies this principle.

Figure 11. Posterior chain progressions usually begin with pull-ups with the body stiffened.

42 VOLUME 32 | NUMBER 3 | JUNE 2010 Figure 12. The asymmetric kettlebell carry uniquely challenges the lateral musculature (quadratus lumborum and oblique abdominal wall) in a way never possible with a squat. Yet this creates necessary ability for any person who runs and cuts, carries a load, and so on. The suitcase carry is another variation suitable for many advanced clients. 6. Get through the sticking points. The passive stretching. Turn your ath- pulse with each stride. However, do technique of ‘‘spreading the bar’’ letes into Kangaroos. For example, consider stretching to correct left/ during the sticking point in the reconsider if a runner should be right asymmetries shown to be pre- bench press is an example of stretched outside of their running dictive of future injury. stiffening weaker joints. range of motion. Many of the great 8. Create shock waves. Make the 7. Optimize the passive tissue connec- runners use elasticity to spare their impossible lifts possible by initiating tive system. Stop inappropriate muscles or to potentiate them to a shock wave with the hips that is transmitted through a stiff core to enhance lifts, throws, strikes, and the like.

ORGANIZING THE LATE-STAGE PROGRAM Finally, consider exercises such as the squat. Interestingly, when we measure world-class strongmen carrying weight or National Football League players running planting the foot and cutting—- neither of these are exclusively trained by the squat (see Ref. (44)). This is because these exercises do not train the quadratus lumborum and abdominal obliques, which are so necessary for these tasks (53). In contrast, spending less time under a bar squatting and redirecting some of Figure 13. The lateral cable hold begins ﬁrst with the hands close to the core and then this activity with asymmetric carries placed further increases the twisting torque challenge (note no twist is such as the farmers’ walk (or bottoms- allowed). Different levels and distance of the handles to the body modiﬁes up kettlebell carry—see Figure 12) (53) the challenge. builds the athleticism needed for

Strength and Conditioning Journal | www.nsca-lift.org 43 Core Training for Better Performance

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