Shirley S. Wang reports on the science of trips and falls:
The body has three main systems that help us stay balanced. The visual system takes in information from the outside world and transmits it to the brain. The proprioceptive system, which incorporates sensory systems throughout the body, tells us how the body’s parts are oriented relative to each other. And the vestibular system, located in the inner ear, focuses primarily on how the head is moving. Generally, if at least two of these systems are impaired, people tend to have trouble with balance.
As people age, the vestibular system becomes less sensitive. Instead, individuals tend to rely more on their vision, which is relatively slow compared with the vestibular system. As a result, older people don’t process information as quickly to correct for missteps, Dr. Cullen says.
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After a fall, older people often say they tripped or slipped. Researchers at Simon Fraser University, in Burnaby, British Columbia, wanted to observe what really happens. The team outfitted a long-term-care facility with video cameras and recorded residents going about their daily lives. They recorded 227 falls from 130 individuals over about three years. Tripping caused just 1 out of 5 of the incidents. The biggest reason for falling—accounting for 41% of the total—was due to incorrect weight shifting, like leaning over too far, says Stephen Robinovitch, a professor in the biomedical physiology and kinesiology and engineering science departments. Other, less frequent reasons for falling included loss of support with an external object, like a walker, or bumping into something.