Purpose: To examine the safety of the use of two wheelchair cushions for healthy individuals with intact sensation and individuals post stroke and spinal cord injury with impaired sensation. The new Ease Alternating Pressure wheelchair cushion will be compared to a static air cushion to examine interface pressure and skin responses in the areas of the buttock and posterior thighs when subjects sit without moving (static condition) and during upper extremity reaching activities (active condition). In addition, comfort, ease of transfer, and postural stability will be monitored while sitting on both cushions under both static and active conditions.

Twenty healthy adults (age range = 20 - 85 years) with intact buttock and bilateral posterior thigh sensation and intact skin integrity will be recruited. Twenty additional individuals (ages 20 - 85 years) with a history of stroke (n=10) and spinal cord injury (n=10) with documented sensory impairment, but intact skin integrity in the area of the buttock and posterior thighs will also be recruited. Individuals post-stroke will likely have impaired sensation on one side of their buttock & leg; whereas, individuals post-spinal cord injury will likely have impaired sensation bilaterally in the buttock and posterior thigh areas. The goal is to recruit equal numbers of males and females with a variety of body builds (height, weight, and body mass index) across the age range in both groups.

Procedures: In one 2 1/2 hour session, participants will a) sit still on [static condition] and b) perform the dynamic task of reaching in multiple directions [active condition] on the Ease alternating pressure cushion and on one static air cushion [randomized for order] for an estimated duration of one hour (32 minutes x two cushions) so that pressure mapping comparisons between cushions can be made. "The motion of the Ease cushions regularly shifts those points of pressure [every 3 minutes], and allows fresh blood to flow where the pressure has been lifted." Pressure mapping will capture the pressure amount, duration, and distribution of pressure between the skin of the buttock and posterior thighs and the wheelchair cushion surface. Documentation of the skin response (skin becomes pink, red, or blanches), and the participant's subjective opinions of comfort, ease of transfer, and postural stability will occur.

Inclusion Criteria:

Control: Healthy adults

• no sensation or skin issues in the buttock or posterior thigh areas

Experimental groups: Diagnoses of stroke and spinal cord injury

• Impaired or absent sensation in the unilateral or bilateral buttock and posterior thigh areas
• No other reasons to have impaired sensation in the buttock and posterior thighs other than stroke or spinal cord injury (i.e. no peripheral nerve damage)
• No current wounds or a history of wounds (past 6 months) involving the buttock, greater trochanters, or posterior thighs

Control and Experimental groups

- Bilateral hips and knees: passive range of motion at least 90 degrees

Exclusion Criteria:

Control and Experimental groups - No self-reported cardiac, pulmonary, orthopedic, or neurological issues that would prevent sitting or performing reaching activities while sitting on the cushions for a one-hour total duration

Experimental group

- No neurological diseases other than stroke or spinal cord injury

Participants, care providers if present, and investigators who are the outcomes assessors will all be aware of which cushion that the participant is sitting on, the participants' diagnoses or if healthy, the static and active conditions described above, and outcome measures results; therefore, no masking is taking place.