Reduced Skin Sensitivity in Older Adults May Contribute to Poor Balance

Have you noticed that as you age, you’re not as quick or steady on your feet as you used to be?  Researchers in the Department of Human Health and Nutritional Sciences have discovered a new link between aging and reduced skin sensitivity in lower limbs that may affect balance and mobility.

A team led by Prof. Leah Bent has found that aging reduces sensory sensitivity in the lower leg, an area that is critical to balance and movement control. Combined with previous knowledge that aging reduces the ability of our feet to sense and feel the ground beneath us, this finding helps explain why older individuals are at much higher risk of trips and falls. 

“Much of our past work has focused on the role of the foot sole in keeping us balanced.  Now we have shown that other parts of the leg, like the shin, lower leg and top of the foot also play a very important role," says Bent.

Bent and colleagues recruited young adults (aged 21-28) and older adults (aged 75-92) from the community to participate in a series of experiments. In the first experiment, participants’ ability to detect a light touch was tested by probing the lower leg with thin filaments. What they found was that older adults had significantly lower sensitivity to touch, tolerating up to 5.5 times more force before noticing the sensation compared to the young participants.  A similar result was also observed for vibration stimuli, with older adults showing significantly lower sensitivity to vibration compared to the younger group.

To find out if these sensory deficits translate into balance problems for older individuals, the team then carried out two tests designed to assess mobility and balance: the Timed Up and Go (TUG) test, and the Functional Reach Test (FRT). 

In the TUG test, participants were seated with their arms crossed and instructed to stand up, quickly walk 3 meters forward, turn 180 degrees, then walk back to their chair and sit down. It took older participants 3.5 seconds longer to perform the test, and the researchers found that time taken to complete the test was relatable to performance on the sensitivity tests, meaning that individuals who had reduced lower limb sensitivity were also slower on their feet. 

The researchers then assessed balance using the Functional Reach Test, where participants were instructed to reach and lean as far forward as possible without moving their feet. The distance reached measures balance by assessing how far the participant can move their centre of gravity without taking a step. Again, the older participants with sensory related deficits did not perform as well in the test, reaching on average only 23 cm before taking a step, compared to the younger group’s 34 cm reach.

“This data allows us to draw a link between lower limb sensory decline and balance deficiencies in older individuals,” says Bent.  “It also suggests that the skin over the lower region of the leg could be an important target for improving balance and mobility in older individuals who have noticed declines in these areas.  For example, low level vibrations could be used to promote sensory enhancement of these skin areas.”

With demographics shifting towards a rapidly aging population, the study helps pave the way for research into new ways of improving balance and reducing falls amongst the elderly. 

This study was supported by funding from the Natural Sciences and Engineering Research Council of Canada.

Read the full article in the Journal of Experimental Gerontology.

Read about other CBS Research Highlights.