Core training for runners: Focus on axial positional neutrality first.

Core training is a term often referring to abdominal exercises that are generally good for everybody including runners to perform for injury prevention and performance. The understanding of the public is shifting beyond just abdominal exercises, thankfully. The goal for this post is to broaden the frame on what core training is and its purpose.

(Axial) Spine, thorax (rib cage) with shoulder girdle, hip girdle

Let’s talk about muscles. So, what are your core muscles? Keep it simple. Just think of the muscles connecting your head to the neck, elbows and knees to your trunk, and all that are in between. In my view, essentially any muscles attaching to your axial skeleton, shoulder girdle, and hip girdle make up your core muscles.

Many professionals specializing in movement performance prefer to use the term “core control” versus “core training” as control implies actively aligning (positioning, orienting, or posturing) the axial system for movement. This could be from any position such as sitting, standing, lying down, et cetera. However, control does not necessarily imply improving the ability to generate force. So “core strengthening” may be used to describe making muscles stronger and/or fatigue resistant. Let’s consider core training as a blend of core control (timing and orientation) and core strength (the ability to produce force). For physics nerds, it may be better understood as kinematics and kinetics.

To enhance one’s understanding of core training, the concept of positional neutrality must be understood. Let’s define positional neutrality as the orientation of the axial skeleton, including pelvis and shoulder girdle, for maximum movement variability of the rib cage, spine, pelvis, arms, and legs relative to the individual. It’s the balance of muscle tension that establishes your starting alignment. In theory, the inability to position the axial skeleton in “neutral” results in either symmetrical and equal suboptimal 3-dimensional range of motion and/or asymmetric equal-and-opposite joint range of motion right versus left and/or skewed rotation observable in the trunk, shoulder, and hip joints unless there is compensation in the movement system. (I know. That’s confusing.) If only the body were this simple, though. One must also consider that there is a degree of asymmetry in the human body that is normal. Traumatic injuries, the parent’s you chose, Wolff’s law / physical stress theory, will also impact an individual’s positional neutrality. The fact is, determining positional neutrality is really difficult for a person to determine without assistance from someone else who knows what he/she is doing.
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Here is a contrived example of why establishing positional neutrality of the axial system is important: I want to run up a steep hill fast. When I push off my left leg, I need my right hip socket to be oriented in a way for me lift or pull my right knee high while still allowing my left leg to push me up the hill. If the start position of my pelvis is skewed in one direction and I go up the hill, the movement will be suboptimal on both sides for different reasons. I would be too good on one side, and not good enough on the other.  If you know Goldilocks, she likes the one in the middle that’s “juuuuusssst right.” Which is to say, if my pelvis is more optimally oriented from the start (positional neutrality) I may be just as good at pushing and pulling on my right leg and my left leg. In theory, this implies improved load distribution on muscles-tendon and joints. I like the sound of that from the perspective of joint health, muscle and tendon recovery time, longevity, and performance.

One of the blessings and curses of being human is an incredible ability to compensate or workaround non-optimal conditions, which is the argument against the need for establishing positional neutrality. But things start to get out of whack when loss of positional neutrality reaches a “not-so-well-defined” threshold that begins to push the available range of motion of joints in one direction. Let’s use another example.

Imagine your shoulder joint as a golf ball (humerus) on a perfectly vertical golf tee (scapula). Gravity is pulling the ball down onto the tee and air pressure is holding it evenly in place on all sides. There is no shear force on the figurative joint and it is happy. Now imagine a strong wind (hypertonic infraspinatus muscle) starts to push the golf ball forward onto the lip of the tee (labrum). The golf ball is no longer aligned in a comfortable resting position through the vertical axis of golf tee unless an equal and opposite force pushes it back onto the tee. Ease the pressure on the figurative labrum, and push the ball back on the tee with your index finger and thumb (subscapularis and supraspinatus). Now tip the golf tee sideways (alter the position of the shoulder socket resting position) so the ball almost falls off. Something has to hold it there, constantly, or it’s going to fall! Again, now there is constant shear stress on figurative joint and lengthening pressure on the labrum and tissues that lengthen over time with sustained stretch.  Is this a good start position?

This scenario in the human body has been described by Shirley Sahrmann as the loss of the PICR (path of instantant center of rotation) of a joint. Ligaments, cartilage, labral tissues, and muscles/tendons begin to adapt as an individual moves further from this ideal position of relative neutrality. The nervous system reorganizes into a new understanding of the body’s neutrality, which may not really be a healthy neutral like the golf tee not aligned with gravity. When ligaments, tendons, and muscle adapt to accommodate new joint position at the shoulder or hip, for example, a degree of instability or impingement toward one direction arises. You may or may not experience pain, but it depends on how much force through a specific range of motion you try to move through and how many times you do it. It just depends on how much it takes to sensitize the tissues.   I can’t tell you how much it will take, but your brain will. “Ouch!”

So what is the biomechanical goal of core training? From an injury prevention perspective, one might say that it is exercise designed for the purpose of restoring or maintaining positional neutrality of axial skeleton. That is to say, it is exercise designed to avoid the positions of instability or impingement defined as moving the extensibility of mostly passive structures (i.e. ligaments, cartilage, labrum) away from the neutral zone of a joint. Some very flexible individuals may have large ranges of motion in all directions (large neutral zone) requiring more control, while others may be very stiff in all directions (small neutral zone). Think of stretchy yoga girl versus 70 year-old stiff guy. So, static stretching may be a form of core training for very stiff individuals if the goal is to improve range of motion. However, pushing into instability where it is not needed through repetitive asymmetrical loading is UNWISE CORE TRAINING!

From a performance optimization perspective, there are two primary goals of core training for runners. 1.) optimizing muscle tension for fatigue-resistant powerful linear motion and 2.) maximizing gas exchange. In other words, core training should complement translation of forces from pushing on the ground into forward linear movement and pumping air into and out of the lungs by twisting the body back and forth repeatedly (A.K.A. running). Right and left alternating

IMG_3664exercise incorporating focused breathing, challenging the thighs-hips, upper arms-shoulders, and thorax is advanced exercise that an be modified in terms of degree of control, speed of movement, and resistance. Body weight exercises on all fours, planking exercises while holding static positions train core muscles. Supported postures on the floor either facedown or on one’s back may be the easiest to feel if the goal is to maintain a static core position. Establishing positional neutrality is where one should start. I believe this requires physical assessment by a professional to specifically determine areas of focus. But, an individual will learn to feel this position and may be able to achieve it while running without exercise before running. With only anecdotal evidence to support the statement, this is what FLOW feels like.

So what is core training? It is performing a movement that challenges the axial skeleton to maintain optimal position for movement of the extremities relevant to the desired task to be performed. It is a blend of control and strength. It is restoring or maintaining positional neutrality first of the axial aspect of the movement system. Its purpose is to maintain the PICR of joints of axial skeleton, shoulder, and hip joints. The abdominals are a big part of the equation, but so are many other muscles. For runners, I will generalize and say that the oblique abdominals, transversus abdominis, breathing diaphragm(s), pelvic diaphragm(s), Latissismus dorsi, multifidi, iliocostalis lumborum, serratus anterior, gluteus maximus, iliacus, gluteus medius, adductors, hamstrings, quadriceps, triceps brachii, et cetera, etc. etc. … are really important. My point is, all muscles are important and play a role in core training.  Ask yourself: What is going to get you to position yourself for the most movement variability from the start position?

In my opinion, exercise fads and programs today revolve too much around ‘mobility’ through aggressive stretching AND strengthening into extension and external rotation (opening up in front) because you don’t spend enough time there all day (sarcasm). For example, imagine sitting or standing all day with what your mother told you was “good posture” (in extension of your spine, perched on the edge of your seat), then going to the gym and doing more extension exercises like back squats, lunges, good mornings or straight leg deadlifts, pull-ups, bench press, Lat pulldown, snatch squats, stretching your hip flexors, gluteals, and avoiding a real curl up where your spine flexes because “it’s bad for your back.” Where is the logic? I am not saying any of those exercises are bad. They have a purpose, but you must look holistically at movement. If you want to make orange juice and all you have are lemons, good luck.

The key takeaways of core training:

  • Core muscles are those that are attached up from the elbows and knees to the axial skeleton, shoulder girdle and hip girdle. Don’t forget the diaphragm right in the middle of it all. Yes, breathing matters!
  • Core training begins with establishing a healthy start position first – Are you oriented appropriately for optimal movement of your arms and legs. Can you achieve positional neutrality?
  • Positional neutrality is the orientation of the axial skeleton, including pelvis and shoulder girdle, for maximum movement variability of the rib cage, spine, pelvis arms, and legs relative to the individual. It is the static observation of a dynamic system.
  • Core training is a blend of timing and body positioning (coordination) and force production.
  • Stretching can be considered core training if it safely enhances the ability to orient / position the body.
  • Learn exercises from an expert that optimize your start position for maximized movement variability without stretching or strengthening into instability or impingement.
  • Add challenge and variability to maintaining neutrality through the axial system during movement. The more specific to the intended task, the better the performance of that task will be. Don’t just do more extension based exercises or planking.

Where resistance training, task specific training, and core training begin and end is a gray area. Be fit, be strong, be coordinated, and keep moving!

 Head for the hills,

-Erik

Post script –

I am a firm believer that being thoroughly assessed by a physical therapist is the best first step to getting serious about exercise, which is why it is mentioned in the post. Assessment should involve a thorough, in-person, one-on-one evaluation ending with relevant patient education. How you move and understanding why you are doing an exercise or modifying a movement habit is important. That said, the goal is not to create fear of moving. The purpose is to empower all humans to move with the precision that maximizes the benefit of exercise and minimizes risk of acute injury or gradual onset of injury. It is far better to keep moving than the alternative.

Mental hurdles for new runners

1) Creating the habit. The first big hurdle is the mental and behavioral aspect of starting something new and sticking to it. Let’s face it, running is an absurd activity. But so is anything that is challenging. Like anything though, the more you practice the activity, the easier it gets. Creating the habit requires mental toughness and a plan. There are no shortcuts, but you can make a new habit stick by cueing yourself through a variety of strategies: 1) sleep in your running clothes 2) leave running shoes in front of your bedroom door 3) buy yourself a running gadget, so you are committed to using it 4) reward yourself if you must 5) set a goal(s) 6) Train with a buddy to create accountability.  Screen Shot 2015-12-03 at 6.45.49 AM

2) FEAR of discomfort (pain). Running can be painful, but it does not have to be! If you take nothing else away from this article remember this: Learning to run relaxed at any speed is the key to unlocking all that is positive about running. Unfortunately, the thought of running can create fear. The perfect example is how “ball sport” coaches ‘unintelligently’ use running as punishment rather than positively reinforcing the behavior of running through slight discomfort. Running should be viewed positively and science proves its benefit when running at any level. The pain gets less and less with practice, and the sense of reward increases. The greater one’s fitness, the more one craves harder efforts. Pushing your level of discomfort and adapting to it is a positive experience.

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3) Patience: Can you delay gratification? Are you a spender or saver? Are you Veruca Salt or Charlie Bucket (see Charlie and the Chocolate Factory)? Running success comes to those who are patient. This is the reality. Aerobic development takes time. Skill acquisition takes time. Impact-proofing your body, specifically to running, takes time. Regularly running too hard or routinely testing your limits increases your risk for injury.  My advice to new runners is to treat running like saving money. View each run as a small investment… “money in the bank,” or “hay in the barn.” Focus on running for time, not pace or distance. Maximizing ones potential takes years. Enjoy the experience celebrating the short-term goal achievements and milestones, but expect there will be setbacks. It will take time to run further, and to run faster.

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4) Making comparisons: Humans naturally compare things. It’s how we make sense of our world. “It’s all relative,” they say. Well, it is hard not to compare oneself to others and oneself to oneself. New runners must learn what comparisons are relevant and when they are relevant. This requires experience. The experienced runner has a good sense of body awareness and can compare a given effort to an expected performance. The new runner wants to compare every run by time or by pace. This is a mistake. Training is non-linear, and focusing on performance of each run can lead to overtraining.

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5) Bending the rules and adapting training: Novices like to follow rules and stay well within the lines. Everyone wants a plan because it is easy to believe, “If I do X, then I will achieve Y performance.” When it comes to training, there is a lot of gray area. Finding one’s training rhythm requires trust in adapting training. Trust comes from experience. This is where having a knowledgeable coach or running mentor can make a difference in your running experience. Based upon one’s personality, he/she may end up overtraining or undertraining. The best training rhythm is individualized based on basic principles, but the rules can be bent. It is an art, and perfecting it is what makes running constantly challenging and rewarding.

To sum up:   Patience and consistency are paramount.   Measure progress in months and years, not weeks.  Allow the power of cumulative efforts to build fitness over time, and avoid constantly comparing one run to the next. Be willing to deal with some short-term discomfort for longer terms gains.   Cultivate the ability to feel relaxed and in control at any level of effort.  Remember, running is a positive experience, not punishment!  Don’t overcook your goose.  Be flexible when following “a plan.”  Adapt your training to keep yourself going.    JUST GET STARTED and experiment to find the rhythm of harder work and recovery that works for you.  Learn from an experienced runner if you need guidance.

 

Tune-Up Running Form to Reduce Knee Pain

If you enjoy running, but nagging knee pain prevents you from getting your weekly mileage fix, try recalibrating your trunk flexion angle. What is trunk flexion angle you ask? Your trunk flexion angle is the bend at your hips or how far your pelvis and torso are from vertical. A recent study by Teng and Powers (2014) found that increasing the average subject’s trunk flexion angle by 6.8o while running at a controlled speed results in a 6.0% decrease in patellofemoral joint (PFJ) force and reduces torque produced by the quadriceps. On the opposite end of the spectrum, running more upright than one’s self-selected trunk flexion angle [closer to a vertical trunk posture] increases PFJ forces 7.4%.   If sagittal plane [side view] mechanics are one of your most salient flaws, this may be a slam dunk for eliminating knee pain.Trunk lean

 

What does the evidence really mean? The underlying premise is that increased peak forces at the PFJ contribute to mechanical trigger for knee pain. Despite a lack of longitudinal studies to prove this strategy reduces knee pain, one could make the argument that a small reduction in PFJ forces with each step over the entire course of a run is significant. Anecdotally, I have seen this work.

Applying this concept to your running can be difficult without visual feedback.  You can get a close estimate of your trunk flexion angle using a mobile motion capture app such as Ubersense that allows you to draw angles on video captured on your smartphone or tablet. Keep in mind that your speed may affect trunk flexion angle. In the current study, subjects ran at 3.4m/s [7:53min/mile].   Trunk flexion angles between 10o and 18o were associated with reduced PFJ peak forces whereas angles of 1-7o were associated with higher peak PFJ forces.

My advice is to learn trunk flexion angle on a moderately steep hill [~10% grade]. Lean forward slightly from your ankles first, then your hips, and you just might find your gluteal muscles. In my experience, teaching people to run uphill and downhill more efficiently with effective trunk lean and cadence for each task can decrease mechanical stress at the PFJ and in turn, reduce the trigger for mechanical knee pain. Happy running!

Source:

Teng HL, Powers CM. Sagittal plane trunk posture influences patellofemoral joint stress during running. JOSPT. 2014; 44: 785-792.

Does improving hip extension mobility actually improve running economy?

Back, pelvis, and hip deep anatomy (anterior view). Psoas and iliacus flex and laterally rotate in open chain movements maintaining the precise axis of rotation in the acetabulum. In closed chain (standing), they are anterior struts for keeping the body upright and stabilizing the lumbopelvic hip complex. The iliofemoral ligament “checks” excessive anterior translation of the femur head in the acetabulum when extending and medially rotating the femur.

Runners, coaches, and other athletes are always looking for ways to prevent injury and become more efficient and economical while running.  In this example, let’s consider our athlete is the weekend warrior with a 40 hour/week desk job or high school student-athlete. This person sits several hours a day, with maybe a 10-minute walking break every hour. Conventional wisdom is that this person will develop a lack of hip extension due to tight/stiff hip flexors.  The hypothesis is that stiff hip flexors shortens stride length negatively impacting running economy, defined as steady-state oxygen consumption at a given running speed.

So does improving hip extension range of motion in individuals “lacking hip extension” improve running economy? According to the evidence, the answer is NO! Though a 20 year old article, this topic has been researched.1 Subjects were young, athletic male college students determined to have “less than normal hip extension” meaning they were unable to passively extend the thigh past 0 degrees. Subjects were divided into a THREE DAYS PER WEEK (yes that is all) hip flexor stretching group and a control group. On average, hip extension improved 9.8 degrees in those who stretched 3 days per week. Despite a statistically significant change in passive hip extension measured using the modified Thomas Test, improved running economy did not occur. The control group (those who did not stretch) actually showed greater improvement in running economy.

What does this mean practically? Improving hip extension through stretching anterior hip structures does not improve running performance at speeds associated with running at paces one could maintain for 10-20 minutes. Could it actually be counter-productive? From both injury and performance perspectives, YES!  Consider that running at faster speeds requires sufficient anterior stiffness to withstand the forces generated by some of the strongest torque producers in the body; the gluteals and hamstrings. It has been speculated with good biomechanical evidence that excessive hip extension forces and joint angles are associated with injury to the anterior hip joint.2 Furthermore, improving your stride length is not primarily the result of greater hip joint extension range but rather more distance traveled during the float phase of running. This requires power, the perfect combination of force production and timing. A well-timed and stronger stretch-reflex in the hip flexors generates a more powerful hip flexion moment. Finding the optimal blend of stiffness and mobility at exactly the right time is what is important.  Improving economy comes down to practicing a skill and improving timing of force production along with other metabolic processes.

How does this affect you? First, understand the goal of your flexibility exercises. If you are stretching because of hip pain, back off stretching and get assessed by your physical therapist. Stretching could be counterproductive even if you get short-term relief of pain. Are you certain you have limited hip extension? Don’t assume that working at your desk creates short and stiff hip flexors. Videotape yourself from a side view running at fast and slow speeds when you are not fatigued. Do you lose your “neutral pelvis” position. Even if you notice that your low back is arched and your pelvis is anteriorly tilted, do not assume you have stiff hip flexors. This often is a coordination issue that can be addressed through specific trunk and pelvic girdle movement awareness.

Related Blog Posts:

Are you sure your hip flexors are tight? If so, why and who cares?

Psoas, please release me… Let me go!

Does excessive sitting shorten the hip flexors?

Sources:

  1. Godges JJ, McRae PG, Engelke KA. Effects of exercise on hip range of motion, trunk muscle performance, and gait economy. Phys Ther. 1993; 73:468-477.
  2.  Lewis CL, Sahrmann SA, Moran DW. Effect of hip angle on anterior hip joint force during gait. Gait and Posture. 2010; 32:603-607.