Propulsion and Heel Impact in the Gait Cycle

What makes up the phases of the gait cycle?


In order to grasp the full complexity of your walking DNA, and the role of metrics such as heel impact force and propulsion, first you need to understand the gait cycle. Comprising two main phases, the gait cycle consists of the stance phase and the swing phase. The stance phase occurs when the foot is in contact with the ground, while the swing phase occurs when the foot is in the air. Although they're defined as two phases, often they take place at the same time with one foot in the air while the other is on the ground, and a very short overlap when both feet are on the ground.

According to Dr. Chris Proulx, Baliston’s Director of Clinical Application and Movement Science, the swing phase of the foot typically comprises 40 percent of the gait cycle. It begins as soon as the toe leaves the ground, then the leg swings through, and it ends when the heel impacts the ground, all of which takes about 0.4 seconds. The stance phase begins with the heel impact putting the foot in contact with the ground, typically comprises 60 percent of the gait cycle and lasts 0.6 seconds. Within the stance phase, there are three distinct stages: heel impact, foot flat, and propulsion. After the heel impact, the toes touch down to the foot flat stage, and then the heel lifts up as the foot moves toward the propulsion stage. Propulsion is the last stage of the stance phase, when your toes push off and your leg begins to swing. This completes the full gait cycle and begins the next one.


What is the importance of heel impact within the gait cycle?


Heel Impact refers to the initial stage of the stance phase. It is the first contact of the foot with the ground during the stance phase of the walking gait cycle and plays a role in several aspects of walking mechanics and efficiency. There are many reasons why the heel impact’s force is considered a measure of your mobility. Specialized components, like fat pads and a network of connective tissues, equip the heel to absorb and dissipate impact forces when the foot strikes the ground.

These cushioning properties help protect the bones and joints from excessive stress and provide a stable base for the body during the initial contact with the ground.

This stable base helps maintain balance and prevents the foot from rolling too far inward or outward, promoting a more controlled and stable walking pattern by also initiating increased muscle and joint activation in the rest of the body to make additional compensations When the heel strikes the ground, the ankle joint is in dorsiflexion (foot pointing upward, to more easily clear the ground), with the muscles on the front of the lower leg contracted and the calf muscles relaxed. The muscles on the front of the lower leg start to lengthen to set the rest of the foot on the ground (instead of just releasing and allowing the foot to slap the ground), for the foot flat stage. Lastly, the heel impact provides instant sensory feedback to the central nervous system, informing it about the terrain and providing information for balance control and gait adjustments.


What is the importance of propulsion within the gait cycle?


During the walking gait cycle, propulsion is the last stage of the stance phase, after the foot flat stage, when your toes push off the ground and your leg begins to swing forward. The propulsion of the foot plays a crucial role in the process of walking. It describes the speed and angle at which your foot leaves the ground as you step. In cases of low propulsion, it signifies an under-engagement of your calf muscles.

Propulsion is crucial for walking because it is the mechanism by which we generate the necessary force that moves us forward. It allows us to overcome the resistive forces, such as friction and gravity, that oppose our forward motion. An appropriate degree of propulsion is essential for several reasons. At a high level, propulsion is integral to the mechanics of walking, enabling us to move efficiently, maintain stability, conserve energy, and achieve our desired mobility goals. It also enables us to overcome the inertia of our bodies and maintain a steady, symmetrical pace, while using energy to cover ground in an economical fashion.

Propulsion is vital for stability and balance while walking. It ensures an upright posture, prevents falls, and facilitates the transition from two feet to one support limb, demanding control and intentionality, especially for those with balance challenges. Finally, propulsion is important for our circulatory system. Good propulsion helps return blood to the heart and this in turn aids circulation across the body. Good circulation helps prevent cold and numb fingers and toes, amongst other numerous important benefits.


How can you optimize your heel impact and propulsion levels?


It's worth noting that the importance of heel impact and propulsion can vary based on factors such as surface conditions, footwear, and individual biomechanics and gait profile. With innovative footwear technology, like the sensor modules at the center of Baliston’s tech-augmented ecosystem, health-focused walkers can get personalized biometrics about their heel impact force and propulsion.

Along with contextualized insights about these two critical actions, the Baliston Connect™ App serves as a wellness coach, providing recommendations on how to reduce heel impact and increase propulsion for optimal walking technique and structural wellness.


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