Table S5. Age-related changes in touch and temperature perception, mobility, and balance

AGE-RELATED CHANGES	DESCRIPTION/CAUSE	IMPACT
Pressure sensitivity	Perception of contact may diminish.	Harder to sense depression of keyboard keys, placement of body against a surface.
Thermal sensitivity	Reduced nerve ending function and less heat retention.	Heightened sensitivity to low temperatures. May not react quickly to dangerously high temperatures.
Body changes	Range of motion decreases. Trunk height decreases. Sitting height decreases. Arm reach decreases.	Ergonomics for average adult does not suit older people.
Slower movement and reflexes	Loss of muscle strength and tone. Declines in neural responses.	Deliberate movement is slower, as is reaction to stimuli. Pursuit of targets (e.g. tracking with a computer mouse) is slower.
Flexibility	Muscles are stiffer and less limber	More limited stretch and reach.
Arthritis and Tremor	Arthritis causes joint pain and stiffness. It affects 50% of seniors and 80% of elders. Some tremor occurs with aging. Parkinsonism, a neurological ailment, causes tremor and affects 1% of those over 50.	Difficult to grip with the hands or to bend the joints, which interferes with performance of everyday tasks (e.g. holding a rail, unscrewing a bottle cap.) Precise, targeted motion is difficult (dialing a phone, inserting an ATM card, setting controls on appliances.)
Coordination	Ability to time and execute movement in a coordinated way is reduced.	Difficult to produce precisely timed sequences of movements (e.g. rapid double click of a computer mouse.) Older people move with deliberation (they trade speed for accuracy).
Balance	Diminished static postural control. Diminished dynamic balance.	Walking speed slows 10% – 20% per decade beyond age 60. Risk of falls increases with age. Older people walk cautiously (they trade speed for balance).