Old age affects fingertip forces when restraining an unpredictably loaded object

Area of Science:

• Neuroscience
• Gerontology
• Biomechanics

Background:

• Fingertip force responses are crucial for maintaining grip stability and preventing object slips.
• Aging is associated with changes in sensory and motor functions, potentially affecting these protective responses.

Purpose of the Study:

• To investigate the impact of old age on automatic fingertip force responses to unexpected tangential loads.
• To compare the response characteristics between young and old adults.

Main Methods:

• Participants grasped a handle subjected to unexpected tangential loads of varying shapes (step and ramp).
• Fingertip forces and response latencies were measured and compared between young and old adult groups.
• Skin slipperiness was assessed to control for this variable.

Main Results:

• Old adults generated larger peak fingertip forces than young adults, despite similar skin slipperiness.
• Response latency for step-loads was similar in both groups (approx. 80 ms).
• For ramp-loads, response latency increased with decreasing load rate and was significantly longer in older adults, with a higher force threshold required to elicit a response.

Conclusions:

• Automatic fingertip responses are not entirely immune to age-related central processing delays, particularly under ramp-load conditions.
• The increased latency and force threshold in older adults suggest age-related declines in cutaneous mechanoreceptor function and central sensorimotor processing.
• These age-related changes may increase the risk of slips and falls in elderly individuals.