Stair gait is a very common task but it is also associated with a high number of falls incidences. Many of the reported incidences occur in adults aged 65 years and older. Extrinsic variables such as changes to the room lighting and insole hardness are two factors that can compromise the balance control system and increase the incidence of falls. Assessments of balance, such as COM-BOS stability margin, and indicators of gait pattern efficiency, such as plantar pressure, force-time integrals and rates of loading and unloading, provide measures concerning efficiency during stair gait. The current research was conducted to investigate stair gait stability, force loading patterns and plantar pressure distributions, with modifications to insole hardness.

Twenty healthy adults (10 young adults, 10 older adults) were recruited from the Waterloo population (mean age = 23.1, SD 2.1;​ mean age = 73.2, SD 5.5) and instructed to descend a 4 step staircase with imbedded force plates. All participants wore similar canvas shoes of varying sizes, and corresponding insole sensors. 12 infrared markers were placed on the individual to record COM motion and BOS location. Participants were instructed to descend the steps for a total of 40 trials, which involved wearing four insole hardness conditions (barefoot, soft, medium, hard) five times in both normal office lighting and dim lighting (300 lux and 25 lux).

This study provides evidence that older adults produce a more cautious, slower gait which generates slower loading rates and unloading rates. This is characteristic of slower transitions and inefficient weight transfer. With stability, older adults produced smaller COM-BOS lateral 'stability margins' forcing their COM closer to the lateral limits. Combined with a large COM-BOS range signifying great variability of COM control, older adults are at a greater risk of falls incidence than young adults. This study also provides evidence that stair gait produces a change in gait pattern from level gait walking, with pronounced pressure distributions exerted onto the toes and tarsals of the foot during stair descent.

Lastly, insole conditions provide evidence that barefoot insoles generate more forces and rates of unloading due to the lack of insole cushioning. Similar to the findings in older adults, the COM-BOS lateral 'stability margin' is smallest in barefoot, and combined with a great variability in COM-BOS range, increases the likelihood of falls while barefoot.

These quantifiable results suggest that older adults while barefoot are putting themselves at a great risk of stair falling. Since age-related changes are inevitable and the preferred footwear of choice inside the home is bare feet, this is a grave issue that should be addressed. These results may be directly adapted to provide future developments of footwear and insole to improve stability in the older adult population during stair descent.