The interaction between leading and trailing limbs during stopping in humans

Area of Science:

• Biomechanics
• Human locomotion
• Motor control

Background:

• Gait initiation is well-researched, but stopping mechanisms are less understood.
• Understanding how the body halts forward motion is crucial for mobility and fall prevention.

Purpose of the Study:

• To investigate the impact of constrained cadence on the body's stopping process.
• To analyze muscle activation and ground reaction forces during walking and planned stopping at various cadences.

Main Methods:

• Electromyography of lower limb muscles (gluteus medius, hamstrings, soleus) and force plate data were collected.
• Participants performed walking and planned stopping at 100%, 125%, and 150% of their normal cadence.
• Muscle onset times, activity duration, and force generation rates were analyzed.

Main Results:

• Increased cadence shortened pre-heel strike muscle activity onset (except soleus) during stopping.
• Soleus muscle showed distinct pre-heel strike activity during stopping and post-heel strike during walking.
• Muscle activity duration remained constant, but lead limb activity and braking forces increased during stopping with higher cadences.
• Rate of force generation increased with cadence, indicating greater reliance on the leading limb.

Conclusions:

• Altering cadence significantly influences the neuromuscular strategies for stopping gait.
• Higher cadences necessitate a greater contribution from the leading limb for braking during planned stops.
• Soleus muscle plays a critical role in both walking and stopping, with timing adjustments based on cadence.