Proprioception: The Sixth Sense

By: Nicole Lovett, DPT, OCS

Source: www.livescience.com

Imagine walking across a room and without warning, the lights go out, and suddenly,  you fall down.  Or you reach into your pocket to grab a quarter and when you look down to see, your hand is empty.   What would life be like if you had to look down at your feet every time you took a step?  Luckily for most of us, this is not the case; we have the ability to sense where we are and where other things are as part of our 6^th sense.  But in rare cases, there is the absence of proprioception, which can occur when a fetus is just developing.  The absence of proprioception occurs when a mutated gene makes the Piezo2 receptor non-functioning. The Piezo2 receptor is an important receptor that integrates mechanical and thermal cues in vertebra mechanoreceptors. (1)  Without it, an individual has no proprioception.  Separate from genetic factors, proprioception can be affected when someone suffers an ankle sprain, an ACL tear, an Achilles rupture, a lumbar muscle strain, or in someone who is afflicted with a neurological disorder.

What is Proprioception?

Proprioception, also called kinesthesia, is the body’s ability to sense its location, movements, and actions in space.   Proprioceptors are specialized nerves that facilitate neurological and physiological responses.    The proprioceptors are sensory and can be found in the inner ear, muscles, skin, joints, tendons, and other tissues.  This is how the brain receives information about the body’s position and to perform certain tasks like, catch a ball, reach for a glass out of the cupboard, or walk in the dark.

How do you test for Proprioception?

There are a variety of ways to test for proprioception. Some tests include:

-     Romberg Test

-     Field Sobriety Test

-     Thumb Finding Test

-     Sequential Finger Touching, or Distal Proprioception Test

Also, the Single-Leg Stance Balance Test with eyes closed would be appropriate to assess proprioception. (2)  These particular tests determine a patient’s ability to sense, move, and act or react. It is a safety-related issue that includes balance and awareness to determine treatment plans that will prevent potential injuries during day-to-day activities.

Single limb stance

 Simply stated, the single-leg stance balance tests for proprioception. With the patient’s eyes closed for 30 seconds, the individual must maintain his or her position for the duration.

Normative data

Age (years)         Eyes closed

20-49                  24-29 sec

50-59                  21 sec

60-69                  10 sec

70-79                  4 sec

How do you train Proprioception?

Once the assessment is complete and altered proprioception is detected, training is essential. When a soft tissue injury occurs, receptor activity is lost. With a loss of receptor activity, proprioception is affected. This is why that during the rehabilitation process, it is imperative to restore receptor activity.   This is done through proprioceptive training in order to re-activate the receptors in the soft tissues. To challenge the receptors one can vary the surface they are standing on or vary the speed of the task or multi-task.  Furthermore, there are three key areas of proprioception input, the cervical spine, pelvic girdle and the sole of the foot.  When training proprioception, pay close attention to alignment in these areas to better improve your outcomes. Improving proprioception will improve a patient’s motor skills, balance, and muscle strength.   Below are three exercises to focus on the three key areas: the sole of the foot, the pelvic girdle and the cervical spine.

Cone pickups on the grass to challenge the lower

extremity and sole of the foot

Deep cervical flexor swiss ball isometrics to challenge the cervical spine

Swiss ball marching to challenge the pelvic girdle

Nicole Lovett is a physical therapist working at Kaiser Permanente. She is a movement science fellowship graduate, Movement Links certified clinician and instructor, and has taught movement concepts in the Loma Linda Residency.

                                

References

---

1. Chesler AT, Szczot M, Bharucha-Goebel D, et al. The role of PIEZO2in human mechanosensation. N Engl J Med. 2016;375:1355-1364. DOI:10.1056/NEJMoa1602812.

2. Bohannon RW, Larkin PA, Cook AC, et al. Decrease in timed balance test scores with aging. Physical Therapy. 1984;(64)7:1067-1070.