The speed at which individuals can initiate a voluntary step could be an indicator of their lifespan and risk of death, according to a study published in the journal Gerontology. Researchers found that for every additional 100 milliseconds it took participants to start a step when distracted, their risk of death increased by nearly 30 percent over the follow-up period.
The study, which followed 120 adults over 65 for 10 to 17 years, aimed to understand the association between balance, posture, muscle movement, and survival rates in older adults. Participants were required to stand for at least 90 seconds and walk at least 10 meters to be eligible.
During the experiments, participants were asked to step as quickly as possible forward, backward, and sideways. They also performed a modified Stroop task, which involves naming the ink color of words printed in mismatched colors, while walking. This dual-task approach allowed researchers to assess cognitive and motor function simultaneously.
The findings indicated that individuals who did not survive the study period took an average of 423 milliseconds to initiate a step, compared to 313 milliseconds for those who survived. Furthermore, each step for non-survivors took 1.3 seconds, while survivors averaged 1.1 seconds per step.
Researchers believe that slower step initiation may signal reduced neurological and physiological resilience in aging, reflecting the brain and body's diminished ability to adapt to stress. Poor balance, for instance, can heighten the risk of falls, leading to serious injuries such as broken bones, muscle wasting, and traumatic brain injuries in older adults.
Walking speed naturally declines with age due to factors like muscle weakness, decreased joint flexibility, poorer balance, and slower brain processing. Calf muscles and nerve signals responsible for motor functions can degrade, leading to miscommunication between the brain and muscles. Additionally, age-related conditions such as osteoarthritis can cause pain that prompts older individuals to slow their pace.
The study authors suggested that incorporating dual-task based assessments into standard clinical evaluations could improve survival prediction and guide early interventions targeting cognitive-motor health. However, the researchers noted limitations, including the small sample size and the study's observational nature, which can only show associations rather than direct causation.