The 30 Second Stretch: Yes, It’s Backed by Science

I’ve heard it all my life. Hold the stretch for about 30 seconds or so, but I never asked why. According to our anatomy and physiology, it matters!

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Mechanoreceptors (Sensory receptors)

What tells us that a muscle is stretching too much or that it needs to stretch more? Our bodies have muscle spindles and golgi tendon organs that provide that particular service.

Muscle spindles are the major sensory organ of a muscle. They are microscopic fibers that run parallel to a muscle fiber. The main function of a muscle spindle is to alert the brain, via the central nervous system, that a muscle is lengthening too far or too fast (Clark, Lucett, McGill, Montel, & Sutton, 2008). When excess lengthening occurs the muscle spindles contract, resulting in micro muscle spasms or a tight feeling.

Golgi tendon organs are located between a muscle and a tendon, also referred to as the musculotendinous junction. Their job is to to relax a muscle when it is placed under excess tension (Clark, Lucett, McGill, Montel, & Sutton, 2008) For example, if you try to lift a weight that is too heavy, then the GTOs will send a message to the muscles involved to stop the action. The relaxation prevents a muscle from tearing.

Hacking the Body With the 30 Second Stretch

You can hack your body’s system by holding a static stretch for a prolonged period of time. Doing so starts a process called autogenic inhibition. In short, autogenic inhibition is an override of the muscle spindles by the golgi tendon organs, allowing the muscles to relax and lengthen (Clark, Lucett, McGill, Montel, & Sutton, 2008). The 30 second rule is based on this process. Generally speaking, most static stretches should be held long enough for the golgi tendon organs to override the muscle spindles– approximately 30 seconds.


References

Clark, M. A., Lucett, S. C., McGill, E., Montel, I., & Sutton, B. (2018). NASM essentials of personal fitness training. Burlington: Jones & Bartlett Learning.

Posture & Health– Why it Matters & What to Look For

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If you are not constantly aware of your posture, the implications, and how to manage it, then you may find yourself with a variety of musculoskeletal problems. However, I will provide you with a simple way to check for and correct postural imbalances over the next few blogs.

First, what are the implications of bad posture?

Misaligned postural integrity can cause imbalances in muscle groups, leading to lessened joint mobility and injury. Typical complaints include low-back pain, ankle sprains, and tendonitis (Clark, Lucett, McGill, Montel, & Sutton, 2008). If these sorts of nagging problems are a motif in your life, then you should take this simple test. 

Check Your Static Posture

One’s static (standing still) postural presentation is an indicator of the consistent positions that the body is held in. You may know your postural tendencies because they are likely linked to your line of work and hobbies, but many people are unaware. Use mirrors, a camera, or have a friend check your posture from different points of view: front (anterior), side (lateral), and back (posterior).

It is important to check the kinetic chain (Feet, Knees, Hips, Shoulders, & Head) from each perspective .

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  1. Front (anterior):
    • Feet & ankles: Parallel and straight; no excessive rotations in or out
    • Knees: in line with the toes; no excessive rotations in or out
    • Hips: parallel to floor (no elevation on either side)
    • Shoulders: level with no excessive rounding
    • Head: neutral with no tilt
  2. Side (lateral)
    • Feet & ankles: leg and foot perpendicular to each other at a 90 degree angle
    • Knees: in neutral position; not hyperextending
    • Hips: neutral; no forward or backward leaning
    • Shoulders: normal curve with no excessive rounding
    • Head: neutral; no excessive jutting forward
  3. Back (Posterior)
    • Feet & ankles: leg and foot perpendicular to each other at a 90 degree angle
    • Knees: in neutral position; not hyperextending
    • Hips: neutral; no forward or backward leaning
    • Shoulders: normal curve with no excessive rounding
    • Head: neutral; no excessive jutting forward

To keep it simple, there are three main structural problems that underlie most issues, so take notes:

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  1. Pronation Distortion Syndrome (Knock knees):
    • feet pronate and are flat (rotate internally)
    • knees rotate internally
  2. Lower crossed syndrome:
    • anterior pelvic tilt (excessively arched lower back)
  3. Upper crossed syndrome:
    • forward head
    • rounded shoulders

If you find problematic areas after running these quick checks, then you may be on to something. You may start to realize that these small imbalances and quirks are the basis of some of the nagging problems you have had. I will provide you with some simple stretches and exercises to alleviate these problems soon.

If everything has checked out thus far, then you have completed level one of your postural assessment!

In the next blog I will take you through level 2, a dynamic postural check that will uncover most  weaknesses or imbalances in your kinetic chain– the overhead squat.

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References
Clark, M. A., Lucett, S. C., McGill, E., Montel, I., & Sutton, B. (2018). NASM essentials of personal fitness training. Burlington: Jones & Bartlett Learning.