Stretch – Shorten Cycle

Muscles work in groupings to both stabilize and move your joints. They have a control system that regulates their length and maintains their natural positioning.  This is controlled through the central nervous system. When one muscle flexes, another must lengthen. This is called the stretch shortening cycle.

As a muscle stretches, its neural receptors are also stretched and they become excited. This activity causes the fibers of the muscle being lengthened to contract and resist the stretch. At the same time, the opposing muscle being flexed receives a signal to relax. This constant tug-of-war is called the stretch or myotatic reflex. It functions to maintain your muscles at a constant length or tone to resist gravity and keep you upright.


Muscle Tone

Muscle tone and muscle strength are two different functions. Muscle tone doesn’t necessarily equate to muscle strength. Muscle tone is a standalone and can be qualified into three different categories. Low muscle tone (Hypotonia), normal muscle tone, or high muscle tone (Hypertonia).

Abnormal muscle tone (when a muscle’s resting length relationships are either too tight or too loose)  is a neurological condition where the signals from the nervous system become confused. This can happen for a variety of reasons. From a functional standpoint, it can be attributed to prior injury and trauma, poor posture, or over training one or a grouping of muscles.


Abnormal Tone

So, recall that muscles work in couplings or groups to help you stay balanced or to move you. If the natural length relationships or tone of the muscles tasked to perform these activities are abnormal, either “hyper” or “hypo”, this will lead to altered movement sequencing, destabilizing the body. This can create excess stress on the whole musculoskeletal system producing injuries overtime.


Glute Amnesia and Hamstring Dominance

A common length relationship imbalance involves the posterior hip muscles (including the glutes and hamstrings) and the anterior hip muscles (including the hip flexors and quadriceps). These muscles make up a force couple that stabilize the pelvis, similar to how your bicep and tricep act upon your elbow.

The hip flexors and quadriceps act to draw the leg in front of you. Functionally, they stabilize the pelvis by pulling it forward (anteriorly tilted). The glutes and hamstrings draw the leg behind you into extension. Functionally, the glutes and hamstrings stabilize the pelvis by pulling it under (posteriorly tilted).

When it comes to Glute Amnesia, the hip flexors and thigh muscles overcompensate (hypertonia) which take over for the glutes (hypotonia) in effect “turning them off”.  As the glutes are the primary hip extensor muscle, the inhibiting effect from the hip flexor dominance will call upon the hamstrings to take over, changing its role from a helper to a boss. This new pattern or strategy of muscle recruitment, involving the overuse of the hamstrings, can lead to a movement distortion syndrome called posterior pelvic tilt.


Posterior Tilt

Since the hamstrings attach to the posterior ridge of the pelvis, their preferential involvement to stabilize the hips, due to the lack of neuromuscular coordination from the glutes, can eventually lead to a lack of mobility and shortening of these muscles. Basically, they overwork, tighten and shorten, altering the posture of the pelvis by rotating it posteriorly (under).  You see this in individuals who seem to have no butt or who rest on the anterior ligaments of the hips.


The Problem

Since the hips are the foundation on which the spine and upper body operate, a posterior pelvic tilt places the body into a compromised position that can affect the movement and alignment of the entire kinetic chain.  Again, sitting up injury cycles. The tilting back also places the vertebrae into a locked position and puts the discs of the lumbar spine under a tremendous amount of strain.


How Does This Happen?

As with what seems to be the case with many movement distortion syndromes, sedentary lifestyles and sitting for long periods of time can lead to the problem.

It’s important to note that there are two phases in its development. First, once hip flexor and quad dominance have set in, your glutes will “turn off”.  This may show up at first as an anterior pelvic tilting (hips tilt forward).  With this neuromuscular dysfunction in play, your body will start to employ an alternative muscle recruitment pattern (including your hamstrings) to perform basic movements, such as squatting, lunging, running, etc. Second, once the hamstrings are consistently recruited to perform these movements, neuromuscular patterns are solidified into your motor behavior.  Now your brain thinks that this is your new normal. Eventually, this can lead to altered joint positioning, creating a posterior pelvic tilting.  Once this happens, without a specific intervention using corrective exercise, accumulative injury cycles above and below the pelvis will ensue.


Yes, There is a Solution!

  1. Recognize which muscles are responsible for proper lumbopelvic hip stability and strengthen them (such as the hip flexor and gluteal complex).
  2. Increase the mobility of the muscles that contribute to posterior tilt (such as the hamstring complex).
  3. Condition your nervous system with functional movement patterns that coordinate the appropriate muscular firing patterns. (You’ll get an example in the video below so read on!)
  4. Reduce movements that require lumbo-pelvic hip control until a neutral pelvic alignment can be maintained (i.e., lunging, squatting, etc.).
  5. Be mindful of your posture when sitting – try to position your pelvis so that you sit directly on top of your sit bones. (a.k.a. try not to let your tailbone rotate too far under).

How to Assess?

Want to find out if you have posterior pelvic tilt? Here is a quick movement assessment you can complete to determine if you exhibit the signs. In front of a mirror and without your shoes on, stand with your feet shoulders-width apart and pointed straight ahead. Raise your arms overhead with the elbows fully extended. The upper arm should be right in line with the ears. Squat down to roughly the height of a chair without letting the arms fall; then go back to the beginning position. Repeat several times.

  1. Did your butt rotate under or did your low back round at the bottom of the squat?
  2. Did either of your knees rotate outward as you squatted down?
  3. Did either of your feet flatten and rotate outward?

If you answered yes to any of these questions, you tested positive for this common posture problem and you’ll want to pay attention to what comes next and watch the accompanying video on how to correct it.


Simple Corrective Methods

Correcting Overactive Muscles

Because we move in patterns, our bodies favor the use of certain muscle groups over others. Since many of us have a tendency towards exhibiting a posterior pelvic tilt, this can place the hamstring complex muscles into an overactive position. You’ll want to lengthen them via self-myofascial release, and then follow the myofascial release with neuromuscular stretching.

Below are the muscles you’ll want to focus on for posterior pelvic tilt this week:

  • Hamstring Complex Self-Myofascial Release for 60 to 90 seconds on each side
  • Stretch or lengthen each for 60 to 90 seconds on each side


Correcting Underactive Muscles

As mentioned above, pain in the body is commonly caused when how we move forces certain muscles to work overtime, while other muscles become lazy and don’t want to function. You’ll need to wake up these lazy muscles through isolated strength movements.

The hip flexor and gluteal complex are the muscles we’ll want to engage this week:

  • Hip Flexors | Standing isolated hip flexion
  • Back extensors and Glutes | Deadlift with thoracic extension
  • Gluteal Complex | Lying Supine Hip Press2 sets on each muscle group 10-15 reps using a slow opening of the muscle, isolated hold at the bottom of the movement, followed by a controlled shortening of the muscle.

Now that you know which muscles are typically underactive and overactive, let’s put it all together for you. Watch the video for a step-by-step breakdown on how to target each of these areas. Before you get started, make sure you have a foam core ball and set of hand weights available.

Start off by applying the techniques three times a week and build from there. Every so often, reassess your posture and see how far you’ve progressed. Soon, you’ll start to see noticeable changes in your body position and mobility!