Biomechanics of Running

Summary

This video delves into the biomechanics of running, contrasting it with walking gait. It highlights increased velocity and ground reaction forces in running, along with a double float phase where both legs are off the ground. The video discusses pelvic, hip, knee, and ankle movements, emphasizing the kinematic, kinetic, and energetic differences between walking and running. It also covers joint moments, torques, and power, illustrating how running efficiency is influenced by muscle mechanics and the spring-mass model of leg movement.

Takeaways

• 🏃 Running biomechanics involves analyzing the kinematic, kinetic, and energetic patterns of the lower body during running.
• 🔄 The running gait cycle differs from walking by having a double float phase where both legs are off the ground, eliminating the double stance phase.
• 🚶‍♂️ Stance phase during running is reduced to about 40% of the gait cycle compared to 60% in walking, with an increased swing phase.
• 🌟 Running involves increased velocity and ground reaction forces, with the center of gravity experiencing less vertical displacement as speed increases.
• 🦿 There's an increased range of motion at the hip, knee, and ankle joints during running, requiring greater eccentric muscle contractions.
• 👣 The foot strike pattern varies with speed, impacting how the runner lands and pushes off the ground.
• 🔼 Ground reaction forces during running show an initial impact force upon heel strike, which can be three to four times the body weight.
• 👟 Running shoes aim to cushion the impact, stabilize the foot, and support the runner's biomechanics efficiently.
• ⚖️ Leg stiffness is a key biomechanical measure in running, representing the effectiveness of the spring-like action of the legs.
• ♻️ The spring-mass model of running suggests an optimal leg stiffness and contact time for efficient energy transfer and reduced metabolic cost.

Q & A

What is the primary focus of the video?

The video primarily focuses on biomechanics of running, comparing it with walking gait and discussing the kinematic, kinetic, and energetic patterns observed during running.

What are the key differences between running and walking gait?

The key differences include increased velocity, higher ground reaction forces during the stance phase, and the presence of a double float phase where both legs are off the ground during running, as opposed to the double stance phase in walking.

How does the stance phase percentage differ between running and walking?

During running, the stance phase is roughly 40 percent of the gait cycle, whereas in walking, it is around 60 percent.

What is the double float phase in running?

The double float phase in running is when both legs are off the ground, resulting in no double stance phase as seen in walking.

What are the two main phases of the running gait cycle?

The two main phases of the running gait cycle are the stance phase and the swing phase.

How does the biomechanics of the joints during running compare to walking?

The biomechanics of the joints during running are similar to walking but with an increased range of motion and more exaggerated movements.

What are the two phases of the stance phase in running?

The stance phase in running is divided into the absorption phase, where the runner lands and absorbs shock, and the propulsion phase, where the runner pushes off the ground.

What is the impact force during running and how is it measured?

The impact force during running is the initial contact force associated with the runner landing from the double float phase. It is reported to be between three to four times the person's body weight.

How do running shoes contribute to the biomechanics of running?

Running shoes are designed to cushion, stabilize, or control rear foot motion efficiently, helping to attenuate the initial impact of the heel strike.

What is the spring mass model in the context of running biomechanics?

The spring mass model in running biomechanics represents the human body where the legs act as a spring and the head, arms, and trunk act as the mass. It helps to understand the energy cost of locomotion during running.

How does the role of hip extensors change from walking to sprinting?

As running speed increases, the contributions of the hip extensors, such as the gluteus maximus and hamstrings, increase to help propel the runner at a faster rate.