Effects of obesity and foot arch height on gait mechanics: A cross-sectional study

Abstract

Foot arch structure contributes to lower-limb joint mechanics and gait in adults with obesity. However, it is not well-known if excessive weight and arch height together affect gait mechanics compared to the effects of excessive weight and arch height alone. The purpose of this study was to determine the influences of arch height and obesity on gait mechanics in adults. In this study, 1) dynamic plantar pressure, 2) spatiotemporal gait parameters, 3) foot progression angle, and 4) ankle and knee joint angles and moments were collected in adults with normal weight with normal arch heights (n = 11), normal weight with lower arch heights (n = 10), obesity with normal arch heights (n = 8), and obesity with lower arch heights (n = 18) as they walked at their preferred speed and at a pedestrian standard walking speed, 1.25 m/s. Digital foot pressure data were used to compute a measure of arch height, the Chippaux-Smirak Index (CSI). Our results revealed that BMI and arch height were each associated with particular measures of ankle and knee joint mechanics during walking in healthy young adults: (i) a higher BMI with greater peak internal ankle plantar-flexion moment and (ii) a lower arch height with greater peak internal ankle eversion and abduction moments and peak internal knee abduction moment (i.e., external knee adduction moment). Our results have implications for understanding the role of arch height in reducing musculoskeletal injury risks, improving gait, and increasing physical activity for people living with obesity.

Fig 1. Example of digital foot pressure data.

These feet represent three participants: one with a higher arch (a), one with a normal arch (b), and one with a lower arch (c). The colors indicate areas of the feet that exert pressure that is graded from low (blue) to high (red) areas of pressure in kilopascals. The high-arched individual on the left (a) is a 31-year-old male with a BMI of 22.06 kg/m². The low-arched individual on the right (c) is male, 28 years old, and has a BMI of 64.14 kg/m². The Chippaux-Smirak Index equals the ratio of the smallest distance of the midfoot (B) and the longest distance of the forefoot (A) as described in Fig 1(B).

Fig 2. Group mean ankle and knee joint moments for the right leg.

We plotted the internal ankle plantar-flexion moment (A-1, C-1), internal ankle eversion moment (A-2, C-2), internal knee extension moment (B-1, D-1), and internal knee abduction moment (B-2, D-2) over the stance phase of walking at preferred walking speed (PWS, A-B) and pedestrian standard walking speed, 1.25 m/s (SWS, C-D). Black lines represent the non-obese group, while red lines represent the obese group. Dashed lines represent the normal arch group, while solid lines represent the lower arch group.

Fig 3. Relationship between BMI and peak internal knee abduction moment for four study groups.

Pearson’s correlations (r) were significant for obese/lower arch group for both speeds, but not for non-obese/normal arch, non-obese/lower arch, and obese/normal arch groups.