Indoor vs. Outdoor Walking: Does It Make Any Difference in Joint Angle Depending on Road Surface?

Area of Science:

• Biomechanics
• Human Locomotion
• Environmental Adaptations

Background:

• Understanding joint angle adaptation to different surfaces is crucial for real-world walking analysis.
• Previous studies often focus on controlled laboratory settings, limiting insights into naturalistic environments.

Purpose of the Study:

• To investigate differences in lower limb joint angles during walking on flat indoor (carpet) versus outdoor (interlocking block) surfaces.
• To evaluate the variability of joint motion in response to distinct real-world road surfaces.

Main Methods:

• Ten healthy young males participated in the study.
• Lower limb joint angles were measured using seven inertial measurement units (IMUs).
• Average and coefficient of variation (%CV) of joint angular excursion were analyzed for indoor and outdoor walking conditions.

Main Results:

• A 45% higher coefficient of variation (%CV) in ankle plantar flexion during early stance was observed outdoors compared to indoors.
• No significant differences were found in spatiotemporal parameters or proximal joint angular excursions between environments.
• Interlocking block pavement exhibited stiffer and more irregular characteristics than the indoor carpet surface.

Conclusions:

• Outdoor interlocking block pavement surfaces, despite appearing flat, induce greater variability in ankle motion during early stance compared to indoor carpeted surfaces.
• Surface characteristics, such as stiffness and irregularity, significantly influence ankle joint adaptation during walking in real-world environments.
• Ankle plantar flexion variability is a key indicator of adaptation to subtle environmental surface changes.