In-shoe plantar pressure depends on walking speed and type of weight-bearing activity in people with diabetes at high risk of ulceration

BackgroundIn evaluating the biomechanical properties of therapeutic footwear, most often in-shoe plantar pressure is obtained during mid-gait steps at self-selected speed in a laboratory setting. However, this may not represent plantar pressures or indicate the cumulative stress experienced in daily life, where people adopt different walking speeds and weight-bearing activities. Research questionIn people with diabetes at high risk of ulceration, 1) what is the effect of walking speed on plantar pressure measures, and 2) what is the difference in plantar pressure measures between walking at self-selected speed and other weight-bearing activities? MethodsIn a cross-sectional study, we included 59 feet of 30 participants (5 females, mean age: 63.8 (SD 9.2) years). We assessed in-shoe plantar pressure with the Pedar-X system during three standardized walking speeds (0.8, 0.6 and 0.4 m/s) and eight types of activities versus walking at self-selected speed (3 components of the Timed Up and Go test (TUG), standing, accelerating, decelerating, stair ascending and descending and standing). Peak plantar pressure (PPP) and pressure-time integral (PTI) were determined for the hallux, metatarsal 1, metatarsal 2-3 and metatarsal 4-5. For statistical comparisons we used linear mixed models (<0.05) with Holm-Bonferroni correction. ResultsWith increasing walking speed, PPP increased and PTI decreased for all regions (p[≤]0.001). Standing, decelerating, stair ascending and TUG showed lower PPP than walking at self-selected speed for most regions (p[≤]0.004), whereas accelerating and stair descending showed similar PPP. Stair ascending and descending showed higher PTI than walking at self-selected speed (p[≤]0.002), standing showed lower PTI (p[≤]0.001), while the other activities showed similar PTI for most regions. SignificanceTo best evaluate the biomechanical properties of therapeutic footwear, and to assess cumulative plantar tissue stress of people with diabetes at high risk of ulceration, plantar pressures during different walking speeds and activities of daily living should be considered.