Ground gradient affects stride-to-stride fluctuations and gait variability in overground walking

Area of Science:

• Biomechanics
• Human locomotion
• Gait analysis

Background:

• Gait variability is crucial for maintaining balance and adaptability.
• Understanding how environmental factors like ground gradient affect gait is essential for injury prevention and rehabilitation.

Purpose of the Study:

• To investigate the influence of different ground gradients (uphill, downhill, level) on gait variability in healthy adults.
• To analyze both the magnitude and temporal structure of gait variability under varying inclines.

Main Methods:

• Ten healthy adults walked on inclines of +10.1° (uphill), -10.1° (downhill), and 0.54° (level).
• Gait kinematics were captured using inertial measurement units.
• Stride time intervals were analyzed for variability using Coefficient of Variation (CV) and Detrended Fluctuation Analysis (DFA-α).
• Heart rate was monitored to assess exertion levels.

Main Results:

• Significant differences in gait variability (CV) and temporal structure (DFA-α) were observed across all conditions (p < 0.001).
• Downhill walking exhibited the highest CV and lowest DFA-α, indicating increased variability and reduced regularity.
• Level walking showed the lowest CV and highest DFA-α, suggesting optimal gait stability.
• Uphill walking presented intermediate values for both metrics.
• Average walking velocity was highest during downhill walking.

Conclusions:

• Ground gradient significantly alters gait variability, with downhill walking imposing the greatest neuro-mechanical demands.
• Metabolic effort (heart rate) during uphill walking did not correlate with changes in the temporal structure of gait variability.
• The findings suggest that eccentric muscle actions during downhill walking play a key role in modulating gait variability.