Thursday, March 22, 2018

Step Back: Do you have Neuromuscular Control?

Introduction: Neuromuscular control (also, often referred to as dynamic neuromuscular stabilization), defined as an unconscious trained response of a muscle to a signal regarding dynamic joint stability, is one of the most overlooked/under-assessed aspects of training and/or rehab. In other words, it is the subconscious activation of deeper, more stable muscles that then allow us to perform other movements in a safer or more efficient way. This has been thought to be an underlying cause of both acute (i.e. ACL tears, etc.) and, probably more often, chronic injuries (i.e. low back, hip, knee, foot, and shoulder pain, etc.). Personally, this is something I struggled with while I was dealing with nearly annual hip flexor strains due to a lack of proper activation of my glutes and deep abdominals.  

Poor neuromuscular control of these deeper, more stable muscles can lead to fatigue and/or faulty movement and activation patterns of the more powerful, larger muscles. For example, poor activation of the gluteus medius and maximus may more commonly display as hamstring, TFL, or knee symptoms/injuries; lower trapezius may cause shoulder pain and upper trap problems; and lack of deep abdominal activation could be the common denominator for a plethora of injuries as the core is connected to nearly everything in the body somehow or another. Upper and lower cross syndrome is a common learning tool many clinicians abide by; a tight (tonic) muscle, usually it is accompanied by a weak (phasic) muscle. The common muscles involved are displayed in the diagram below. The good thing is that we can assess and address these activation patterns with specific exercises.

The following are the common poor activation sites followed by how to assess on yourself and, if you find that you have limited activation of that muscle group, how to address the pattern.

Glutes: May be the cause of many underlying problems such as, but certainly not limited to: knee valgus (specifically during squats) & pain due to the association with the knee angles and glute medius strength; low back pain; hip pain; and more specifically ACL tears.

First method, perform a set of glute bridges (10-20) and be honest with where you feel “the burn”. If you feel it in more in the hamstrings vs the glutes, you may have a poor activation pattern of the glutes. If normal glute bridges don’t produce the desired burn, upgrade to a single-leg glute bridge and assess again. 
Another option, lying prone, have another person palpate the proximal hamstring, glute max, and both ipsilateral and contralateral erector spinae at the same time (yes, it takes a little planning and particular hand placement). From this position perform a leg extension and have the person tell you the order in which these specific muscles fire. Correct activation patterns should be: glute max, hamstrings, contralateral erector spinae, then ipsilateral erector spinae, respectively. However, often times it turns out to be the ipsilateral erector spinae, or even the thoracolumbar/shoulder girdle that starts the movement pattern1. If your pattern does not follow the former order, you may have some glute neuromuscular training to work on.

Grab yourself a mini-band and place it right above the knees. Bodyweight squats, making sure the knees in line with the toes and aren't caving in is a good place to start. Follow that up banded side-lying clamshells, and standing or side-lying banded hip abduction exercises (be wary not to let the contralateral hip drop, or cave-in, while performing this exercise aka keep the pelvis neutral).

Deep Abdominals: Our deep abdominals, specifically the transverse abdominis, when contracted help create intra-abdominal pressure tensioning the thoracolumbar fascia in the low-back in turn stabilizing the spine. It is interesting to note that the thoracolumbar fascia also provides a connection from the hips to the upper extremities via the latissimus dorsi muscles, therefore a connection to possible shoulder pain with poor activation of this muscle group. The deep abdominals also provide a connecting point for the upper and lower body as the transverse abdominis runs from along the bottom rib to the iliac crest which helps explain the hip pathology issues. 

Lie on your back with knees bent (hook-lying as seen in Figure 1A below), palpate your anterior superior iliac spine (ASIS) and then fall off the ridge of that anterior and medially to feel for your transverse abdominis (remember this is the deepest abdominal muscle so you may need to apply some pressure). Keeping your fingers there on both sides, completely relax the core muscles with a normal breathing pattern. Then to assess, breathe in a way that “brings your belly button to your spine” and feel to see if your transverse abdominis has contracted (spongy/muscular feeling under your fingers). If you can feel it, great! Now try that same thing in standing. If there was no contraction or a minimal contraction, you can try the same thing in a side-lying position.2 

Another method would be to raise the legs individually keeping the knee bent, while in the same hook-lying position. If you feel a deep abdominal contraction prior, or simultaneous with the leg elevation, that is a good thing. The core should be bracing your body for the movement. However, if the core is not activating with that movement, excessive stress may be placed through the hip flexors and/or the low back muscles.

The following exercises are from a study done by Dr. Noelle Selkow, ATC in which she and her colleagues found that doing these progressions 2x/week for 4 weeks improved both activation and strength of the transverse abdominis (a key deep abdominal muscle).3

Exercise 1: Hook-lying “abdominal drawing in maneuver (ADIM)” with weekly progressions (Figure 1); 3x10 max contractions with 10 sec hold (15 sec rest).

Exercise 2: Side-Bridge with weekly progressions (Figure 2); 3x10 max contractions with 10 sec hold (15 sec rest).

Exercise 3: Quadruped progression, or more commonly, bird-dog progression (Figure 3). Week 1: 3x10 max contractions with 10 sec hold (15 sec rest). Week 2: Alternate arms every 2 sec during contraction. Week 3: legs extend every 2 sec during contraction. Week 4: opposite arm/leg extension alternating every 2 sec during contraction

Another simple way to address the deep abdominal work is to work on a 90/90 breathing technique as demonstrated here by Dr. Zach Long from Barbell Physio. 

Lower Trapezius: Many shoulder pathologies (impingement, rotator cuff, frozen shoulder, etc.) stem from an inadequate ratio of upper to lower trapezius activation, with the latter being the muscle that is often “forgotten about”. Without adequate force coupling between these two muscles, the scapula is more often out of a desired position which leads to pinching, aching, etc. within the shoulder joint.
Notice lower trap arrow pointing down and 
toward the spine

Lying prone with arms in a “Y” position as seen to the right (insert picture), attempt to pull the scapula in the direction of the arrow (down and in towards the spine). If you can do that, keep the scapula set in that position and attempt to elevate the arm 1-2 inches. Any limitation, either not able to set the scapula or failure to keep it set, may indicate a lower trap activation issue. 

Another way to assess is to perform shoulder abduction and watch in the mirror to see if your upper trap is shrugging the shoulder up. If so, attempt to pull the scapula down and back using the lower trap and relaxing the upper trap. 

Exercises for this activation pattern include the general I, Y, T, & A’s on a bench, bent over, or on a stability ball; band or cable face pulls; and rows, lots of horizontal rows. The key to these exercises are to keep the scapula set (pulled down and back) allowing for better humeral movement and decrease compensation patterns. Also, just working on overall better posture and limiting the rounded shoulders and the more recent "text-neck"/forward head posture. 

Conclusion: Sometimes lifting the heaviest weight isn’t always the most beneficial workout. Hard to believe, right? If you’re having nagging injuries, chronic pain, or are in the business of preventing injuries (prehab), assess yourself for these 3 common muscle patterns. A factor that I didn’t mention in the “address” sections is that in addition to learning to activate and strengthening the muscle, you should also work to stretch the “tight” muscle groups in reference to the Upper or Lower Cross diagram. For example, a weak lower trap should be strengthened but the pecs, upper traps, and levator scaps should also be stretched. 20 minutes 2x/week could have you feeling better, moving better, and training better for the long haul. 

1.  Lehman, G. J., Lennon, D., Tresidder, B., Rayfield, B., & Poschar, M. (2004). Muscle recruitment patterns during the prone leg extension. BMC Musculoskeletal Disorders5, 3.
2. Richardson C, Jull G, Hodges P. Therapeutic exercise for lumbopelvic stabilization: a motor control approach for the treatment and prevention of low back pain. Edinburgh: Churchill Livingstone; 2004
3. Selkow, N. M., Eck, M. R., & Rivas, S. (2017). TRANSVERSUS ABDOMINIS ACTIVATION AND TIMING IMPROVES FOLLOWING CORE STABILITY TRAINING: A RANDOMIZED TRIAL. International Journal of Sports Physical Therapy12(7), 1048–1056.

1 comment:

Eoin Morgan said...

Relieving tight hip flexors and tension is not easy. source In sprinting high knee lift is associated with increased stride length and therefore considerable attention is given to exercising the hip flexors.