true trunk stability

Proper Trunk Stability- The Muscular Guide Wires Within

Let’s first start with a definition. Kibler et al., 2006 from the Journal of Sports Medicine, defines Core stability as “the ability to control the position and motion of the trunk over the pelvis to allow optimum production, transfer and control of force and motion to the terminal segment in integrated athletic activities.”

INTRODUCTION

Feedforward subconscious automatic trunk stabilization via core stability is crucial for efficient biomechanical sport specific movements in order to maximize force transmission and minimize joint loads. Core stability is defined most accurately as the “the ability to control the position and motion of the trunk over the pelvis to allow optimum production, transfer, and control of force and motion to the terminal segment in integrated athletic activities” (8).  High-level athletes must be able to transmit force across the body in the most efficient way possible in order to reduce the chance of peripheral muscle overuse and increased athletic performance with the least energy expenditure. In order to achieve this, the athlete must first focus on perfecting the correct core activation patterns while simultaneously achieving optimal breathing patterns demonstrated in last month’s article. Core activation and breathing are the foundation for core stability. We would never train an athlete to sprint before they could walk without faults. We must do the same when treating the core. The goal for core stability with all high-level athletes should be for them to attain subconscious feed forward trunk control and core stability with optimized breathing patterns under stress and fatigue. In this article, I will discuss how to best achieve this through evidence-based core anatomy and physiology, higher level core testing, and sport specific core training progressions.

ANATOMY

Core musculature includes the muscles of the trunk and pelvis that are responsible for the maintenance and stability of the spine and pelvis (8). They help in the generation and transfer of energy from large to small body parts during many sports activities (8). These muscles include the scalenes, deep neck flexors, sternocleidomastoid, pectoralis, intercostals, diaphragm, rectus abdominis, transverse abdominis, internal and external oblique, pelvic floor, quadratus lumborum, and lumbar paraspinals as well as any muscles, which can affect these muscles. The core musculature is needed for force transmission across and through the body segments and in order to keep the trunk rigid when receiving or producing impact force. The diaphragm and pelvic floor, which work in synergy with the oblique’s and transverse abdominis, have also been postulated to be major contributing muscles needed in order to attain true trunk stability and control (6,7). They do this by helping to increase the pressure in the abdominal cavity, otherwise known as intraabdominal pressure, which leads to overall increased trunk stiffness (6,7,14,15). A common misconception is the training program that primarily focuses on specific single abdominal muscle hypertrophy or training these muscles as dynamic extremity prime movers, which can lead to muscle imbalances, fatigue, overuse, and injury.  When we take a deeper look into the posterior superficial trunk muscle histology, especially the thoracic and lumbar erector spinae, we see muscle fiber characteristics that are predominantly large type I (slow twitch) fibers. This provides further evidence that these muscles are preset to perform best in postural isometric endurance and stability, aiding in force transmission and trunk stiffness (13).

Further, when we look at the deep spinal rotators and intertransversarii muscles, we see that these muscles have 4-7 times the muscle spindles as even the next most superficial multifidi muscles and that these muscles are most active with passive motion not active motion. This supports the hypothesis that this layer acts as potential vertebral position sensors or as a proprioceptive system not as prime movers or force generators (14). Due to this common practice of dynamic selective hypertrophy training as the best way for the abdominal muscles to gain true strength and stability it becomes important to shed light on the amount of actual muscle force needed to attain this sought after stability. To further reinforce this point, evidence has shown that muscular endurance is more protective of the spine than absolute strength and surprisingly in order to stiffen the spinal segments we only need up to 10-15% of maximal voluntary contraction for rigorous activity (12,14,15). If that is true then; Is core strength really about absolute strength gained through hypertrophy training? It seems that current evidence would point towards a training program that focuses on training muscular coordination and isometric core endurance. Then working that back into sport specific motions in order to achieve subconscious, feedforward, core stability and passive stiffness with optimized breathing patterns under sport specific stress and fatigue (5). With these principals our athlete can transmit forces at the correct time during the integrated athletic movement.

EVALUATION

After a comprehensive breathing and core activation examination is completed the core musculature should be further evaluated under load and trained based on sport specificity. This can be completed in many ways, but I will focus on static testing which correlates to current evidence and trunk tissue histology and function. One very popular extensor chain muscle endurance test is the Sorensen extension test; due to the original studies’ large population, in depth pre and post-testing criteria, as well as the studies’ 1-year follow-up results. This study showed that low back extension holding times in 30-60 year old males of less than 176 seconds were predictive of low back pain during the next year, whereas a holding time greater than 198 seconds predicted an absence of low back pain (3). Other studies have shown that hold times of less than 58s was associated with a three-fold increase in the risk of low back pain, when compared to a hold time of greater than 104 seconds (12). This test has since been shown in various studies from 2001-2017 to have clinical significance regardless of sex, age, and physical activity level. Due to the difficulty in order to set up and perform the Sorensen test in the clinic and for a home exercise program, another test which has been useful in my practice to test low back and posterior chain static endurance is a static bent over weighted hold. This is done at 45 degrees of hip flexion and slight knee flexion. This static posterior chain test is similar to that of the Sorensen test but in a closed chain isometric standing position, with the trunk at 45-degree angle from the ground, using hip flexion. The best part is the evaluation becomes the treatment and is already setting the athlete up to brace and hold in a functional position. To make up for the lost torque on the trunk muscles and posterior chain due to this test’s 45 degrees hold position vs parallel to the ground in the Sorensen test the patient needs to hold 55.34% their body weight for men and 54.54% their body weight for females, which are standardized trunk to lower extremity anthropomorphic ratios per sex split between two hands. This does mean that grip strength will also play a role in this test but this can be bypassed via wrist straps or other aids. Now I understand there are many more components at play with this version of a closed chain posterior muscular endurance test so feel free to try it and if it is not applicable for your patient or your find other obstacles with this form of testing, fortunately, there are many other tests to use. Please refer the video attachment for how to perform and progress this modified evaluation from static testing into a dynamic treatment, as I am currently in the process of obtaining an IRB in order to prove the correlation of the two evaluation tests.   

For the athletic population, I suggest using Mcgill’s static trunk endurance normative values as they combine the sit up, side plank, and Sorensen extension test to come up with normative cut off values as well as muscle endurance ratios with a younger athletic population (14,15).  Other tests supported by sport-specific function or return to sport evidence that should be considered involving the lower extremity with trunk control would be the lower quarter Y-balance test or for the upper extremity the upper quarter Y- balance test (4). Another test with considerable athletic evidence that incorporates trunk control and upper extremity speed and ballistic motion would be the Closed Kinetic Upper Extremity Test (CKUET) (17,18). One part of higher level core evaluation that is consistently missing in current practice is evaluating the core in these positions or with these tests while the athlete is under systemic or sport specific fatigue then comparing those to normative values or the athletes non-fatigued values. Mcgill describes one version of this with the running population, where the athlete would sprint until fatigued and then hold side plank as long as possible to evaluate and eventually treat fatigue related core impairments (14,15). This concept should be translated into all trunk and body evaluative testing as you would not send a patient with a tibiofemoral pathology back to sport without seeing the quality of their movement when they are both fresh and fatigued for objective proof of complete resolution of contributing movement faults. With fatigue, we see a decrease in position sense/ proprioception of sport-specific central and peripheral joints leading to increased tissue overload and damage. (11,19). Therefore, this is of upmost importance because each high-level athlete must be able to maintain automatic feed-forward core stability and trunk control with optimized breathing patterns while under stress and fatigue.

EXERCISES

The concept of training for sport specific core muscle symmetry and co-contraction are pertinent when thinking of functional trunk exercises. As previously stated, when athletes are training trunk stabilizing muscles as prime movers, in isolation for the majority of the workout, or in ways that overemphasize certain overdeveloped trunk muscle groups we run into huge problems. This type of training can lead to suboptimal movement patterns and compromised central stability. Current evidence and muscular histological studies show that static/ isometric trunk stability exercises/ training programs will both increase cross sectional area as well as increase passive trunk stiffness of the core musculature which will then aid in force transmission, increased trunk stability and control, with reduced pain. (9,10).

Some exercises to consider would be lumbar extension or side plank isometric holds on a roman chair at the gym with the hip pad positioned at different vertebral levels. Then we would progress this exercise by adding in a secondary component related to the sport such as the holds while catching a football, dribbling, shooting. Another exercise that is beneficial for trunk rotational faults would be side step outs without allowing trunk rotation while holding a weighted pulley or band with both upper extremities static at the navel level. You could also trial the static 45 degree hip flexion holds with a theraband around the thighs to promote posterior chain contribution and then add increased weight and lower extremity motions in all planes with the trunk held stable as shown in the accompanying video.

 
Lumbar Extension Isometric Hold

Lumbar Extension Isometric Hold

Side Plank Isometric Hold

Side Plank Isometric Hold

Lateral Step Outs

Lateral Step Outs

 

Side plank variations with the lower or upper extremity open chain limbs performing sports specific motions are also great functional exercises to perform that have been shown to maximize trunk activation at minimal spine load. Due to the high demand of some sports it may become important for the athlete to work on core stability with ipsilateral or contralateral lower and upper extremity open and closed chain functional patterns. If they are related to sport specific movements trial neutral spine association or dissociation with crawling, supine frozen bear rolling, bird dog, or dead bug type exercises with possible cable machine, free weight, or theraband resistance attached to upper or lower extremities.  

 
Side Plank Isometric Hold

Side Plank Isometric Hold

Dead Bug Static Hold

Dead Bug Static Hold

Dead bug Alternating Arm/Leg Variation

Dead bug Alternating Arm/Leg Variation

Static Bear Crawl

Static Bear Crawl

Bear Position with Perturbation

Bear Position with Perturbation

Bear Crawl

Bear Crawl

 

Most of these exercises can be progressed with them being performed on unstable surfaces or with external perturbation training but keep in mind as we increase the demand on the trunk we increase the muscular demand and co-contraction and thus can increase the spine load which can be important when treating those athletes with concurrent spinal irritability, so progress slowly and with purpose. Also, keep in mind that it has been shown that there is no single core exercise that challenges every abdominal muscle at the same time, therefore we must pick a multitude of exercises that are most sport specific each session in order to fully optimize core stability and coordination (2). During the same training session, after priming the trunk with specific activation, strength, and coordination exercises, incorporate sports related functional movements with the athlete focusing on conscious timing of the trunk muscles. This can be done prior to and during limb movement and then progress them towards attaining an automatic subconscious activation pattern of proximal stability prior to and during these movements. Also spend time on correct sport specific movement patterning, paying close attention to shoulder, hip, and trunk association or disassociation while still having a baseline of passive automatic feedforward trunk stability and control. Next try all of these under local muscle or cardiovascular fatigue in order to test core stability and coordination with increased diaphragmatic demand.

If we put it all together, one possible version of a graded progressive treatment protocol for the trunk would focus on breathing with core activation and timing while accepting the weight of lower and upper extremities in supine, sitting, and standing. Then core isometric training, working towards evidence-based normative values progressed with sport specific motions (14). Concurrently or after this phase focusing on conscious to unconscious automatic timing and activation of the core musculature with corrected sport-specific movements. Finally, work on all of these concepts under fatigue, on unstable surfaces, or with perturbations in order to achieve the most beneficial sport specific stability possible.

I hope this article shed light on the importance of automatic proximal stability before and during distal mobility through evidence-based static and functional core training for all integrated athletic movements and that from these tests and sample treatment examples we can further progress each athlete to stabilize and efficiently transmit force in order to reduce proximal or distal tissue injury and fully optimize each athlete.
 

EVALUATION REFERENCE SHEET

Isometric Trunk Tests:

Side Plank Right: >=83 sec

Side Plank Left: >=86 sec

Side Plank Right/ Left Endurance Ratio: <.05 seconds Difference

Flexor Endurance Test: >=134 sec

Extensor Endurance Test: >=173 sec

Flexion/ Extension Endurance Ratio: <1.0 seconds Difference

Side Plank/ Extension Endurance Ratio: <.75 seconds Difference

Upper Quarter Y-Balance Test:

High school male and female baseball/ softball players: Use for R to L differences, No difference between throwing and non-throwing arm

Lower Quarter Y-Balance Test:

 > 4cm anterior – 2.5x greater risk

 Composite score < 94% - 6.5x greater risk

CKCUEST Test:

Collegiate Male Baseball players: Normative mean value is 30 touches

Collegiate Football players: Cut off value of less than 21 touches could identify athletes at risk for future injury  

CITATIONS

  1. Anderson, David; Barthelemy, Lindsay; Gmach, Rachel; and Posey, Breanna, "Core Strength Testing: Developing Normative Data for three Clinical Tests" (2013). Doctor of Physical therapy Research Papers. Paper 21.
  2. Axler, C.T. and McGill, S.M. (1997) Low back loads over a variety of abdominal exercises: Searching for the safest abdominal challenge. Medicine and Science in Sports and Exercise, 29, 804-811.

  3. Biering-Sørensen F. Physical measurements as risk indicators for low-back trouble over a one-year period. Spine (Phila Pa 1976) 1984 Mar;9(2):106–19.

  4. Butler, Robert J. et al. “Bilateral differences in the upper quarter function of high school ages baseball and softball players.” International Journal of Sports Physical Therapy 9.4 (2014): 518–524. Print.

  5. Cholewicki J, Juluru K, McGill SM, et al. Intra-abdominal pressure mechanism for stabilizing the lumbar spine. J Biomech 1999; 32 (1): 13-6: 76-87

  6. Hodges PW, Richardson CA. Contraction of the abdominal muscles associated with movement of the lower limb. Phys Ther. 1997;77(2):132-144.

  7. Hodges, P W et al. “Contraction of the Human Diaphragm during Rapid Postural Adjustments.” The Journal of Physiology 505.Pt 2 (1997): 539–548. Print.

  8. Kibler WB, Press J, Sciascia A. The role of core stability in athletic function. Sports Med 2006; 36(3): 189-98.

  9. Kim S, Kim H, Chung J. Effects of spinal stabilization exercise on the cross- sectional areas of the lumbar multifidus and psoas major muscles, pain intensity, and lumbar muscle strength of patients with degenerative disc disease. J Phys Ther Sci. 2014;26(4):579–82.

  10. Lee BC. et al. “Effect of long-term isometric training on core/torso stiffness.” Journal of strength and conditioning research.(2015) Jun;29(6):1515-26.

  11. Lee, Hung-Maan et al. Evaluation of shoulder proprioception following muscle fatigue. Clinical Biomechanics , Volume 18 , Issue 9 , 843 – 847. 2003.

  12. Luoto S, Heliovaara M, Hurri H, Alaranta H. Static back endurance and the risk of low-back pain. Clin Biomech (Bristol, Avon) 1995;10: 323–4.

  13. Mannion AF et al. Muscle fibre size and type distribution in thoracic and lumbar regions of erector spinae in healthy subjects without low back pain: normal values and sex differences. Journal of Anatomy. 1997;190(Pt 4):505-513.

  14. McGill, Stuart. Low Back Disorders: Evidence-based Prevention and Rehabilitation. Champaign, IL: Human Kinetics, 2002. Print.

  15. McGill, Stuart. Ultimate Back Fitness and Performance Fourth Edition .Waterloo, Ontario Canada, 2009. Print.

  16. Page, Phillip, et al. Assessment and treatment of muscle imbalance: the Janda approach. Human Kinetics, 2010.

  17. Pontillo M, Spinelli BA, Sennett BJ. Prediction of in-season shoulder injury from preseason testing in division I collegiate football players. Sports Health. 2014;6(6):497-503.

  18. Roush, James R., Jared Kitamura, and Michael Chad Waits. “Reference Values for the Closed Kinetic Chain Upper Extremity Stability Test (CKCUEST) for Collegiate Baseball Players.” North American Journal of Sports Physical Therapy : NAJSPT 2.3 (2007): 159–163. Print.

  19. Tripp, Brady L, Eric M Yochem, and Timothy L Uhl. “Functional Fatigue and Upper Extremity Sensorimotor System Acuity in Baseball Athletes.” Journal of Athletic Training 42.1 (2007): 90–98. Print.

  20. Wainner RS, Whitman JM, Cleland JA, Flynn TW. Regional interdependence: a musculoskeletal examination model whose time has come. J Orthop Sports Phys Ther.2007;37(11):658–60

Breathing: the Forgotten Precursor to True Trunk Stability


INTRODUCTION

“Core Stability” is defined as the ability to control the position and motion of the trunk over the pelvis in order to attain optimum production and transfer of force and motion to the athlete’s terminal segments in all integrated athletic activities (6). Wow! No wonder we all focus on core strength and coordination with our high-level athletes. However, can you say you focus on or at least perform a breathing screen with every athlete before diving into high-level core stability and coordination? If not you are missing a huge part of the core stability screening and training for athletic optimization. If you overlook these possible breathing and core activation faults the athlete may never gain the best core stability to optimize their throwing, running, and kicking, which can lead to increased risks for peripheral tissue injuries.

With high-level athletics, every bit of energy transfer makes a difference in performance and the body uses the core to transmit this energy. All of these purposeful athletic movements must start with the feed-forward proximal stability mechanism in order to transmit force across the whole body. If this force cannot be transmitted up the chain, and the same speed and velocity of sport’s motion is to be maintained, then the small peripheral joints must work harder to make up for the lost kinetic force. Thus, athletes need correct respiratory function and core stability for efficient biomechanical, sport specific function, in order to maximize force generation and minimize joint loads (6).

 

Respiratory/ Core Evidence Based Connections

So how does breathing function with core stability? Simply put, if you cannot breath properly you cannot brace properly. Breathing and core stability go hand in hand, as the majority of the respiratory muscles work synergistically with the core muscles or even function as both. The diaphragm and pelvic floor have been postulated to be major contributing muscles in order to attain true trunk stability by helping to increase the pressure in the abdominal cavity, otherwise known as “intra-abdominal pressure” (5). Thus the forgotten precursor to abdominal bracing and true core stability is a comprehensive, static anthropomorphic and dynamic breathing assessment, with a trunk feed-forward activation assessment prior to high-level training.

Respiratory and core muscles are most important for what can be referred to as feed-forward, subconscious, automatic stabilization. Athletes need to be able to attain this trunk control and core stability with optimized breathing patterns under stress and fatigue. This is not always inherent in every athlete, but is pivotal in order to provide stability prior to and during all motions. A simple concept to remember is: proximal stability before and during distal mobility (12). Another component to reducing peripheral tissue injury is reducing the time-to and time-under fatigue. This is through optimal systemic oxygen input to the body, which requires efficient energy transfer through core stability. When an athletes supply of oxygen, via the respiratory system or passive force transmission via core stability fail, the athlete will rely more on their peripheral tissues and joints in order to compensate for loss of whole body kinetic force transmission. Which has been shown to increase peripheral tissue fatigue, reduced proprioception, and increase incidence of tissue injury (13). This is mainly due to the fact that with fatigue we see a decrease in position sense/ proprioception of sport-specific central and peripheral joints leading to increased tissue overload. It was shown in 2003 and 2007 that throwing athletes had decreased upper extremity proprioception at the onset of and during throwing under fatigue (9,13). This study and many others have supported Janda’s theory that fatigue is due to a reduction in the feedback from the muscle spindle, which then affects proprioception and posture (12). It can also be postulated that not only peripheral but also central joints have improved stability due to appropriate proprioceptive function and feed-forward control (12). Regional interdependence is a theory that states that seemingly unrelated impairments in remote anatomical regions of the body may contribute to and be associated with a patient’s primary report of symptoms. In this case, poor trunk motor coordination and timing can lead to peripheral or central joint/ tissue overuse and injury (15).

 

Respiratory/ Core Evidence Based Anatomy and Training

The core musculature is responsible for the preservation of spine and pelvis stability, which aid in the generation and transfer of energy or force from the trunk to distal segments during movements (6). These muscles can include the scalenes, deep neck flexors, sternocleidomastoid, pectorals, intercostals, diaphragm, rectus abdominis, transverse abdominis, internal and external oblique, lumbar paraspinal muscles, and pelvic floor muscles. Athletes also need thoracic static structures to be in optimal positioning in order to create an environment for respiration and core musculature to work most efficiently.

So which should we focus on first? Well breathing of course! You cannot brace or play any sport with perfection if you cannot breath, and the athlete’s need to attain the best breathing posture will supersede the best posture for stability if they are not trained to work together. Ideal posture or positioning for core stability will be compromised in order to put the body into a position to optimize breathing and maintain respiration, as the body will always choose oxygen and respiratory function over stability and trunk control. (12). Clearly this can come at a large price if you are out of breath, unstable, and are about to be hit by a 300 lb linebacker in the NFL. Studies have shown time and time again that these muscles cannot, and should not, solely be trained to work in isolation. The transversus abdominis muscle is only able to produce 1-2% MVC in isolation before the aid of the internal oblique, pelvic floor, and the other trunk muscles are activated (10/11). The diaphragm and transversus abdominis muscles in healthy adults both fire synergistically prior to isolated lower extremity, upper extremity and trunk movements in order to stabilize the trunk independent of the breathing cycle phases (4/5). Therefore, in order to activate the optimum trunk musculature we must focus on feed-forward core bracing with correct breathing patterns which will be ultimately trained under fatigue.

So now we see that the core muscles should be trained in synergy with breathing and can’t be isolated, we can move onto the thought of absolute core muscle strength. Throughout the article I have talked about the importance of this feed-forward, subconscious, automatic stabilization in order to stabilize the body for limb motion and in order to transmit kinetic forces. I focus on the timing of these muscles and activation patterns because of the previous studies stated and the fact that it has been shown that we only need up to 10% MVIC of the trunk muscles in order to provide joint stiffness in lumbar spine for integrated full body movements (2/10/11). Also, even if you think the only way to gain core stability is through strength; you should know that it has been shown that instability at a joint may still be present with normal strength measurements (3). Since we don't need much absolute strength for increased stability or force transmission, and even with absolute strength joints can show instability, it seems that evidence is pushing towards core faults being mostly coordination faults rather than absolute muscle power faults. Therefore, we should focus our efforts on breathing, endurance, timing, and feed-forward autonomic core activation, with progression to sport specific difficulty in order to attain true useful trunk stiffness and functional athletic stability.  

 

Respiratory Objective Exam

There are many different ways to perform an objective exam to assess respiration and they can be tailored to the individual athlete you are evaluating. I will discuss one method that I prefer for a comprehensive respiratory and core activation evaluation. Take note that this is a supine examination; therefore standing posture, movement, strength, and coordination examinations should supplement the exam that I will describe below.

In the supine position, with the athlete relaxed, have both legs flat or both knees bent and feet flat (hook-lying) on the table, and visually examine the athletes static/ dynamic anthropomorphic structures with subconscious tidal breathing. Take note of the chin neck angle, as this can cue you into which muscles/ joints are being over or underutilized and will cue you into the athletes preferred cervicothoracic positioning. Visually evaluate the cervical musculature and the tracheal position. Visually examine the asymmetries of the sternum, clavicles, ribs, and pelvic tilt. Notice any scarring, increased and decreased muscle tone and bulk, especially in the lateral obliques, as they may be a site of decreased trunk stability. Observe for thoracic cage deformities such as pectus excavatum/ carinatum, scoliosis, excessive kyphosis, and any other deformities or irregularities picked up from other examination procedures in this position. The anteroposterior chest diameter should be less than the transverse diameter. The normative ratio of AP to transverse diameter is about 0.70 to 0.75 in adults, which increases with age (14). These static structures are the foundation, which the core and respiratory muscles have to work from, and it can greatly affect their ability to stabilize and transmit force throughout the body. After the visual static structure assessment has taken place, watch the athlete’s preferred subconscious breathing pattern at tidal volume, taking special note of abdominal/diaphragmatic filling and rise as it relates to chest rise. Reassess with the athlete taking a couple full inspiratory breaths as well. Ideally we want to see less chest compared to diaphragmatic rise. Rise in terms of where the body chooses to move from with resting tidal and full inspiration breathing. This is important because if the athlete is relying on anterior-posterior chest expansion over diaphragmatic expansion in order to breath then this may lead to increased motion at the lumbo-throacic junction which can lead to increased spine and tissue stress, especially in times of fatigue.   

Next, if needed, place one hand on the chest and one on the abdomen of the athlete just below the costal angle. This will further help you to assess the motion of diaphragm and chest as the athlete breaths at tidal and full inspiratory volume. Place your thumbs tip to tip at the xiphoid process with your other fingers and palms lying flat on the ribs facing towards the athlete’s shoulders in the intercostal spaces to feel for any rib expansion abnormalities and in order to estimate the costal angle. The normal values of this angle is 90-110 degrees. This angle is important because it will give you insight into which muscles may be inhibited or hypertonic, as well as see if the athlete has any set anthropomorphic abnormalities of the rib cage, and/or thoracic spine. Remember, rib angles as well as the costal angle are a direct reflection of the thoracic spine orientation, and it most certainly is appropriate to evaluate the thoracic spine if you feel this is the structure of anatomical variance.

A palpatory exam is also an important part of a full respiratory and trunk control exam. Palpate all quadrants of the abdominals to feel for increased or decreased muscle tension or any tissues with increased sensitivity. You have already assessed active rib mobility with breathing, but it may also be important to further assess passive rib mobility by placing your hands flush against the ribs on the anterior thorax with the addition of broad overpressure. Ask yourself these questions; Are they starting the breathing motion correctly or are they stuck in an expiratory rib/ thorax position possibly categorized by a narrower than 90 degrees costal angle with more vertically positioned ribs? One theory is that this could be due to or lead to increased external oblique or rectus abdominis resting tension and reduced internal oblique activation or resting tension. Are they starting the breathing motion correctly or are they stuck in an inspiratory position categorized by a wider than 120 degrees costal angle with more horizontally positioned ribs? One theory is that this could be due to or lead to increased internal oblique activation and reduced external oblique resting tension. Lastly, is the athlete asymmetrical with one side of his or her ribcage flared up and out or held down and the other working within normal limits? As a grossly simplified muscular guide, the internal oblique will most likely increase the rib angle (ribs appear more horizontal) and costal angle and can pull the ribs in an anterior to posterior direction as well as in an inferior and lateral direction. Or conversely they could cause a slight anterior pelvic tilt due to its line of pull. The external oblique will most likely decrease the rib angle (rib appears more vertical) and costal angle and can pull the ribs in an anterior to posterior direction as well as an inferior and medial direction or conversely could cause a slight posterior pelvic tilt due to its line of pull. Whereas the rectus abdominis will pull the two sides of the rib cage slightly medially and inferiorly decreasing the costal angle or conversely could cause a slight posterior pelvic tilt due to its line of pull. There are numerous ways to treat these findings and many different continuing education classes that one could take in order to affect the athlete’s faults as comprehensively as possible. However, explaining all of the ways to treat these findings is out of the scope of this article, so do what you know and see if you can make a change. Having said that, any faults and abnormalities picked up with the visual and tactile breathing assessment should be assessed further and should be normalized with soft tissue, joint mobility, or coordination treatment via tactile, verbal, and visual cueing until the patient can correct the abnormalities with tidal breathing and maximum inspiration or until they are as minimal as possible.

 

Core Activation Objective Exam

Next up is the core activation objective assessment. Place your thumb of each hand on left and right inferior lateral quadrants of the athlete, just medial and superior to the ASIS. At the same time place your middle finger or pinky finger on the athlete’s posterior lateral trunk, superior to the posterior iliac crest, and at the same vertebral level as you thumbs (Pincer grip).  In the respiratory assessment you felt AP motion of the thorax and with this new grip you now have your hands in a great position to feel for lateral, anterior and posterior abdominal wall filling. Next, with you hands in this position have the athlete breath with normal tidal volume and with maximal inspiration, feeling for the filling of all four palpated cavities at the same rate and depth. The timing and fullness of all quadrants should be the same, as we want the athlete to fill their cavity equally and cylindrically in order to achieve the optimal intraabdominal pressure and core stability. If they cannot do this, then your work starts here. Again these faults should be normalized with soft tissue, joint, or coordination training via tactile, verbal, and visual cueing until the patient can correct the abnormalities or until they are as minimal as possible.

Next, with the athlete lying in supine, lift their legs into a 90/90 position, supporting their full lower extremity weight onto your thigh with your foot on the table. Another possible option for overhead athletes would be to lift both of their arms overhead (to 140 degrees of shoulder flexion) with their wrists supported on your thigh. Next, verbally cue the athlete to slightly lift their arms or legs off of your passive support until they accept the full weight of their limbs. You want the athlete to lift their own arms or legs off of your support as opposed to you pulling your passive support away from them, as this will most closely simulate their automatic preferred abdominal activation pattern. During this phase of testing observe their core for their timing and quality of their preferred automatic motor activation as they start to support the weight of their legs or arms. Look and then feel (using pincer grip) the abdominal cavity as a whole, as we want to see symmetrical cylindrical filling just prior to limb motion. This would show optimal proximal stability before voluntary limb muscle activation and motion. Observe the navel for any motion, as this can be an obvious cue into trunk muscle activity. If all of the core muscles are working in synergy the navel should have very little to no movement. If you see navel motion as they accept the distal weight, this will cue you into areas of increased muscle pull and activation or decreased pull and activation as the navel is pulled towards the direction of dominant muscles and away from non-dominant muscles. Look and then feel for cues of an overactive rectus abdominis, which can be seen with increased abdominal rise anteriorly, greater than lateral abdominal wall filling. Ideally you would want to see and feel cylindrical core activation, which is equal and symmetrical in timing, pressure, and filling just prior to active limb motion. This should be done without any external cueing, as this would show that the athlete has automatic feed forward core stability in preparation for limb motion and mobility.

At this point in the core activation evaluation it is important that you try to see if they can change their pattern towards optimal with minimal cues. You can be as creative as you like, but try to get the patient to understand what normal is and why it is important, and then have them strive to achieve that with minimal cueing. Tactile cues for abdominal filling may be as simple as having the athlete breath into the area where there is decreased absolute filling or decreased rate of filling. You can facilitate this via your tactile pincer grip pressure, having them focus on the pressure of the table, or their own tactile pressure via self-pincer grip. You can manually push down and set the ribs in the correct position and then see if the patient can breathe while actively holding that corrected rib positioning with their core muscles. Can they then progress to deep breathing while filling all cavities symmetrically with that corrected positioning held. Finally can they support their lower and upper extremity weight and then move their lower extremities in the supine position while actively holding their ribs in that corrected position with proper breathing. Verbal cues can be simple and can include “breath into this part”, “fill/ firm this part of your stomach/ back” in order to attain proper breath/core muscle filling.  One of the best verbal muscle activation cues shown to increase bracing in current literature is “Stop your urine flow” (8). Your athlete may think this is elementary training, but then at that point I usually just say some version of “Your right, this is such minimal motion, and your even lying on your back. But you can not even lay here and hold the weight of or move your legs with proper core activation for stability, support, and power, what makes you think you can sprint, hit, or jump with correct core activation and stability in order to optimize your movement and prevent injury?” it usually drives home the point that they already expressed, which is that this training is so simple compared to usual higher level athletic integrated motion or weight training and you have just showed them that they can’t do it correctly.

        This entire assessment will allow you to see if the abnormalities found can be changed or trained in order to attain the optimal thorax positioning for maximally effective automatic feed-forward abdominal bracing with limb motion and correct deep breathing. If you have now assessed your athlete and found that they are able to correctly breath and brace with lower or upper extremity motion then the next step is higher level trunk muscle testing and strengthening in order to maximize the athletes full core stability potential (which will be the focus of my next article). Be creative, as I have only given you one version of possible testing, otherwise you would be reading a large book on this topic not a small concise post. Evidence is always changing and there is always more ways to address each fault found with each athlete. So get out there and build truly effective athletes.
 

Breathing/ Bracing Quick Sheet

Visual:

Anthropomorphic: chin neck angle/ trachea/ clavicle/ sternum/ costal angle/ ribs/ pelvis

Soft Tissue: anterior cervical musculature/ 4 quadrants/ navel position / scars/ muscle tone

Diaphragm vs chest rise: 2:1 or 3:1 ratio

Costal angle: 90-110 degrees

Ratio of AP to transverse rib diameter = 0.70 to 0.75 in adults

Check all with tidal and deep breathing

Palpation:

Diaphragm vs chest rise 2:1 or 3:1 ratio

Costal angle 90-110 degrees

Rib angles

All abdominal quadrants for muscle tone and increased sensitivity

Lower abdominal, anterior and lateral wall filling with tidal and deep breathing for timing and absolute volume with pincer grip

Muscle Actions:

Internal oblique: Increase the rib angle (rib appears more horizontal) / costal angle, can pull the ribs in an anterior to posterior direction + inferior and lateral direction or slight anterior pelvic tilt due to its line of pull.

The External oblique: Decrease the rib angle (rib appears more vertical) / costal angle, can pull the ribs in an anterior to posterior direction + inferior and medial direction or slight posterior pelvic tilt due to its line of pull.

Rectus abdominis: Pull the ribs medially and inferiorly or slight posterior pelvic tilt due to its line of pull.

Bracing Activation Cues:

Verbal: “Stop Your Urine Flow”, “Think of filling the lateral abdominal/ posterior wall”, “breath into the tactile cue”, “blow out forcefully”

Tactile: PT pincer grip, PT hands on chest and diaphragm, Athlete to feel table under the body, Athlete’s own hand on chest and diaphragm or on abdominals with pincer grip,  manual joint and muscle techniques, blocking rib or joint motion with deep breathing, using muscles to hold ribs in the proper position

Visual: Athlete to watch abdominal rise, Athlete to watch belly button motion in mirror held above by PT; athlete to watch video of correct bracing or see diagrams

 

Citations

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8.              Lee, Diane D. “The Pelvic Girdle: An Integration of Clinical Expertise and Research”. Churchill Livingstone, Elsevier, 2013.

9.              Lee, Hung-Maan et al. Evaluation of shoulder proprioception following muscle fatigue. Clinical Biomechanics , Volume 18 , Issue 9 , 843 – 847. 2003.

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