This 6th sense helps our body understand where it is in space and how to move in response to countless signals between the brain and millions of receptors throughout the body.
To move safely in this world, our body needs to understand where it is in the environment. Key among the players accomplishing this complex task is the special sense (some would call it the 6th sense) of proprioception, which is the awareness of joint position. Knowing what position the joint is in allows the body to determine how to move. Proprioception is joined by kinesthesia, the knowledge of joint movement, and neuromuscular control, the efferent response to an afferent input. All 3 combine to provide dynamic stability or the functional component of movement. This article is a quick look at proprioception.
Scientists as far back as the 1550s were writing about a sense of position and movement, but it wasn’t until the 1880s that the term kinesthesia was introduced. Then in 1898, Goldscheider described proprioception as the conscious awareness of body and limbs including passive motion sense, active motion sense, limb position sense, and the sense of heaviness. And 10 years later, Sherrington introduced the term proprioception while writing of the unconscious component that controls muscle tone and posture.1,2
Proprioception works with sensory receptors throughout the body—including 400,000 proprioceptors in the feet—that are constantly sending messages through the central nervous system to the cerebral cortex and after processing are essentially ignored, or a message may be sent to the nerves to respond. In the case of movement, that message tells a lower extremity nerve to recruit a muscle for walking or running or climbing a flight of stairs.
Researchers learned long ago that we do not have to actually “think” to make these movements in response to proprioceptive inputs. Turns out, because of the predictability of everyday movements, our minds anticipate the countless proprioceptive signals sent and received daily and only sense or “feel” something is different when there is a discrepancy between the signal actually sent and what we anticipated.1 One example of this phenomenon is when you come to the bottom of what you thought was a standard set of stairs only to find yourself jolted by a short step. Your body hadn’t thought about where it was in relation to all the other steps, but you became very aware of where you were in space when your foot slammed into the ground earlier than expected at the bottom. Worse is when you come to the bottom and the ground isn’t where your foot expects to find it and you suddenly find yourself falling forward, your extended foot frantically trying to find the ground that it expected to be 12 inches beneath the last step you were solidly on.
Proprioception also plays a role in dynamic postural stability, balance, motion, and orientation via its coordinated efforts with the vestibular system in the inner ear. This super-hero combo is an ideal target for both injury prevention and improved motor function. (Conversely, impaired proprioception is what the police are looking for when they ask a driver to touch their finger to their nose in a roadside sobriety test.)
Injury and Proprioception
Because proprioception is essentially a nonstop feedback loop between the proprioceptors in the muscles and joints and the central nervous system, impairment or injury to any body part can harm this critical sense. The risk of diminished proprioception occurs as a natural part of aging, but it can be accelerated by several disease states that strike in mid- and later life, such as diabetes, arthritis, stroke, multiple sclerosis, Parkinson’s disease, and Huntington’s disease. Herniated disks and brain injuries can also lead to diminished proprioception.
In younger crowds, injuries to joints, such as ankle or knee sprains, joint replacements, and surgical repairs, such as anterior cruciate ligament (ACL) reconstruction, are the prime culprits.
Symptoms of injured proprioception include:
- Balance issues (eg, trouble standing on 1 foot, frequent falls [even from a chair])
- Uncoordinated movements (e.g., can’t walk a straight line)
- Clumsiness (eg, walking into walls, dropping things)
- Poor postural control
- Trouble recognizing the force or strength needed to complete a task
- Avoiding movements and activities due to fear of falling
What becomes clear when reviewing the list of symptoms is that diminished proprioception leads to instability. Instability in aging leads to falls. Instability in sports leads to injury.
The good news is this: research has shown that proprioception, once injured, can be improved, and better yet, newer findings are proving that certain types of exercise can act as preventive measures.
Proprioceptive Training & Treatments
Although there is no definitive definition of proprioceptive training, a systematic review by Joshua Aman et al from the School of Kinesiology at the University of Minnesota proposed the following:2
Proprioceptive training is an intervention that targets the improvement of proprioceptive function. It focuses on the use of somatosensory signals such as proprioceptive or tactile afferents in the absence of information from other modalities such as vision. Its ultimate goal is to improve or restore sensorimotor function.
In the review, Aman et al2 looked at 51 studies that used 5 training approaches: active movement/balance training, passive movement training, somatosensory stimulation training, somatosensory discrimination training, and combined/multiple system training. Study participants had an array of conditions and some of the included studies were for injury prevention in healthy individuals.
Overall, proprioceptive training resulted in an average improvement of 52% across all outcome measures. Applying muscle vibration above 30Hz for longer durations (i.e., min vs. s) induced outcome improvements of up to 60%. Joint position and target reaching training consistently enhanced joint position sense (up to 109%) showing an average improvement of 48%.
In their conclusion, the researchers observed:
First, proprioceptive training can be effective in improving proprioceptive function: 29 of 51 studies reported improvement rates above 20%.
Second, longer lasting interventions seem to produce greater benefits. Training regimens lasting 6 weeks or longer tended to yield relatively higher improvements in proprioceptive and/or motor function, although somatosensory stimulation has been shown to yield very rapid gain within a single session or a few hours of intervention.
Third, proprioceptive training is applicable to a wide range of clinical populations. Patients suffering from proprioceptive impairment may benefit from the procedure disregarding if the cause of the impairment is neurological or musculoskeletal in nature.
Other authors have reported specific findings in a variety of populations: Xu et al3 reported on a group of older, long-term Tai Chi practitioners who had significantly better threshold to detection of passive motion at the ankle when compared to a sedentary group as well as an active cohort. But there was no difference at the knee joint.
Likewise, Patrella et al4 showed that active adults over age 60 had significantly better proprioception (as measured by reproduction of joint position procedures) when compared to sedentary adults. The authors suggested their results were indicative of activity as a factor slowing the loss of age-related proprioceptive function.
In a 6-year study of professional basketball players, a proprioception injury prevention program focused on single stance.5 The program grew progressively in 2-year increments from classic proprioceptive exercises to the use of interactive electronic stations that provided quantifiable data. During the last 2 years, the intensity and training volume increased while duration of the sessions decreased, reflecting the changing science. Results, which appeared in the Journal of Strength and Conditioning Research, demonstrated an 81% reduction in ankle sprains and a 78% reduction in low back pain, both of which were statistically significant. Knee sprains were reduced 65%. Overall, proprioception control improved significantly by 72%. The authors concluded that improving single-stance proprioceptive control could be an effective program for reducing ankle sprains, knee sprains, and low back pain.
The literature is full of articles describing foot orthoses that correct abnormal foot biomechanics, but one manufacturer has introduced a proprioceptive “non-orthotic” specifically designed to strengthen the dome arch at the center of the foot. In its Therapeutic line of insoles, Barefoot Science (London, Ontario) uses a system of 7 color-coded “plugs” to strengthen the arch of the foot and increase muscle function up the kinetic chain. “When we stimulate the mid arch of the foot, it improves balance and performance,” according to Scott Grisewood, RMT, in a video posted on the company’s website. Grisewood is a registered massage therapist with nearly 30 years of experience in sports medicine working with professional and amateur athletes across Canada.
The research seems clear that certain types of exercise can help restore lost proprioceptive function and may be able to strengthen joints in an effort to prevent further injury, and more importantly, prevent initial injury. Those exercises should aim to:
- Improve spatial awareness
- Improve balance
- Increase the sense of joint position
While there may be no single “proprioceptive” exercise that specifically improves proprioception,6 exercises that build strength in these 3 capacities have an evidence base that supports their use in a variety of populations.
Janice T. Radak is Editor of Lower Extremity Review.
The Two Minute Club
By Geoffrey Little
The critical component to building a strong athlete in all movements is balance. Whether the athlete is walking, jogging, running, changing direction, batting the ball, or fielding the ball, balance is key to proper movement.
As a coach, we have to understand if balance is improving or failing for each athlete. A standard test to understand and evaluate balance is to ask our athlete to stand on 1 leg with their eyes open for 60 seconds, and then repeat on the opposite side. If the athlete falters on 1 or both legs, the test should be implemented as a fundamental movement in their training.
Practicing balance for 5–10 minutes per day should give the necessary result in 2–3 weeks on average. Once the athlete is capable with their eyes open to balance on each leg individually for 60 seconds, we welcome the athlete into the prestigious “Two Minute Club.”
Once the “eyes open” component is mastered, the athlete is again tested with standing on 1 leg with their eyes open, but when ready, we have them close their eyes and see if they can hold that position. The goal is to have them stand on 1 leg with eyes closed for 60 seconds, then repeat on the other leg.
Why? We test this because the athlete’s proprioception will be in constant use during a game because so much is done on 1 leg. The athlete’s eyes are on the game, but it’s his feet that read the ground. If the athlete’s proprioceptive ability is good, his feet will read the ground quicker and he can move quicker. Training your proprioception ability will increase the speed at which your brain is giving messages to your muscles resulting in an increased input. Any delay in proprioception will increase the ground contact time and that is detrimental to athletic performance.
This test can be used to train people with less-than-optimal proprioception; just have them continue to train with eyes closed until mastered. Balance and proprioception should improve fairly quickly. If progress stalls, they should seek further help from the coach and athletic trainer.
Geoffrey Little is a junior at SUNY Plattsburgh who studies sports medicine with a future in sports rehabilitation treatment. He works with Microgate USA in Mahopac, New York.
- Proske U, Gandevia SC. The proprioceptive senses: their roles in signaling body shape, body position, and movement, and muscle force. Physiol Rev. 2012;92:1651-1697.
- Aman JE, Elangovan N, Yeh I-L, Konczak J. The effectiveness of proprioceptive training for improving motor function: a systematic review. Front Hum Neurosci. 2015;8:1075.
- Xu D, Hong Y, Li J, and Chan K. Effect of tai chi exercise on proprioception of ankle and knee joints in old people. Br J Sports Med. 2004;38:50–54.
- Patrella RJ, Lattanzio PJ, and Nelson MG. Effect of age and activity on knee joint proprioception. Am J Phys Med Rehabil. 1997;76:235–241.
- Riva D, Bianchi R, Rocca F, Mamo C. Proprioceptive training and injury prevention in a professional men’s basketball team: a six-year prospective study. J Strength Cond Res. 2016 Feb;30(2):461-75.
- Ogard, WK. Proprioception in sports medicine and athletic conditioning. Strength Condition J. 2011;33( 3):111-118.