Designed to Run - The Human Gait Cycle
Human beings are amazing running machines! As human beings we are designed to run, and even take flight for short periods of time! The synergistic actions of a runner’s body provides stability, balance, shock absorption, and propulsion. Much of our running ability has to do with our body’s capacity to store and release elastic energy.
Running is a synergistic dance between multiple structures, involving the body's entire kinetic web, with each structure playing a critical role.
Surprisingly, running and walking are very different from each other. One of the main differences is that a good runner is airborne most of the time. When we observe an elite runner, the actual contact/support phase with the ground makes up only 30-40% of the runner’s gait cycle. Most runners (efficient runners), are airborne 60-70% of the time (1,2). Running is as close to flying that we are going to get.
This unique pattern has developed for a very good reasons - energy conservation and efficiency. The longer a runner is in contact with the ground, the more energy a runner wastes.
Think of running from an evolutionary perspective. The more energy that is expended, the less likely our ancestors were to escape from a predator, or catch an animal they were hunting (3).
MADE TO RUN
At the last Fascial Congress in Berlin (November 2018), I had the pleasure of sitting in on a lecture with Dr. Daniel E. Lieberman (Professor of Human Evolutionary Biology at Harvard University). (Photo to the right: Dr. Abelson at the Fifth International Fascia Congress in Berlin.)
Dr. Lieberman explained how we may not be the fastest animal on the planet, but despite this, our incredible bipedal locomotion system is beautifully designed to run long distances to allow us to run down our prey.
Our human evolutionary path has given us an amazing locomotor system designed to help us hunt and travel across long distances. But the story does not stop there! Let’s jump forward from our prehistory, half a million years to our modern lifestyle and see how things have changed.
Unfortunately, we now live in a very sedentary society that is extremely good at reducing the effectiveness of our body's energy storage and elastic recoil system. We have moved from 'running down' our prey to 'driving' to supermarkets that only two blocks away. Yet at the core of our physiology, we continue to possess an amazing locomotive system that we can still tap into.
THE GAIT CYCLE
Our Gait Cycle is the foundation of our running efficiency and elastic recoil capabilities. Running efficiency is all about energy conservation - the less energy we waste, the greater the performance, and the lower the potential for injuries. Most runners are surprised to find out that a lot of lost energy (or energy leaks) is through the body's compensating motions from old injuries and not just due to poor technique. To get a better idea of what I am talking about, let's first dive into the gait of a runner!
A complete gait cycle starts out when one foot strikes the ground, and ends when the same foot strikes the ground again. The gait cycle of a runner can be divided into two main phases, the Stance Phase and the Swing Phase. As we make our way through the gait cycle, take a few minutes to consider how our body is designed to dissipate force while at the same time storing energy for release through the process of elastic recoil.
Tip: Practitioners need to understand this critical information to effectively analyze their patients gait when working to treat and prevent injuries, while improving athletic performance!
THE STANCE PHASE OF GAIT
The Stance Phase is divided into three distinct sub-phases:
Take off - Triple Extension
Initial Contact - Foot Strike: Stance Phase
This is the initial phase of the running cycle, when the runner's foot first touches down. Bio-mechanically, when the runner's foot contacts the ground several distinct actions occur at the same time:
The runner's knee flexes.
The tibia internally rotates.
The ankle joint rolls inward (subtalar joint pronates).
This combination of actions is incredibly efficient at disseminating the force of the runner’s foot strike (4).
Ideally from an efficiency perspective, during this stage (ideally) the runner’s foot should be just slightly ahead of the runner's centre of gravity.
Why? The body's centre of gravity is found in the lower abdominal area in a region between your hips. Touching down with your foot just slightly ahead of your centre of gravity substantially reduces excessive braking of the body.
Unfortunately, most runner's tend to land too far forward and end up needlessly braking their forward motion with each stride. This substantially decreases running performance by wasting energy. As we mentioned, efficient running is all about energy conservation, especially when you get into long distance running (5,6).
Mid Stance - Braking: Stance Phase
This stage is often referred to as the braking or absorption phase. During this phase, the runner’s knee and ankle will be in a position of maximum flexion. The amount a runner flexes their knee varies with their running style.
Being in this position of maximum flexion performs two import functions:
First it allows the runners muscles, tendons, and connective tissue to absorb two-to-three times the runner's body weight.
Secondarily, it turns the runner’s legs into an incredibly efficient mechanism for storage of elastic energy.
During the Initial Contact - Foot Strike phase we indicated that braking was a bad thing; but at the Mid Stance phase, it really is not. The braking action at this phase, creates a stable base and allows for maximum elastic recoil for energy storage.
A key point here, is that if the runner is going to take advantage of this elastic recoil they must have a stable base. In order to have a stable base, the runner must have strong, flexible, unimpeded glutes, quadriceps, hamstrings, and calf muscles to achieve maximum elastic recoil (7, 8). Tissue quality counts!
The runners core stability is also extremely important at this stage. Without strong hip muscles (glutes and external hip rotators), low back muscles (erector spinae, and the abdominal muscles - internal and external obliques, transverse abdominus, and rectus abdominus) the runner would not have a stable base and important energy from elastic recoil will be lost (9).
In preparation for the next sub-phase (Take Off) the runner's foot moves from a position of pronation to supination. This turns the runners foot into a rigid lever which aids in forward propulsion by increasing elastic recoil efficiency(7,8).
Between Mid Stance and Toe Off the runner’s load of force is shifted from the front of their shins to the runner's calf muscles (gastrocnemius and soleus).
Clinical Tip: At Mid-Stance, the runner's foot should have stopped pronating. Excessive pronation at this stage will cause instability, possibly leading to injury.
Take Off – Triple Extension: Stance Phase
There is a very fast transition from the Mid-Stance phase to the Take Off phase.
This stage is often also called the Propulsion Phase, referring to the synergistic actions of the foot as it becomes a rigid lever, with the knee and hip joints extending, and the lower extremity externally rotating. These are the actions that create a propulsive force that drives the runner forward (primarily by elastic recoil). The leg muscles predominantly control position and create rigidity for release of energy (7,8).
During the Take-Off phase, the runner’s pelvis tilts forward to keep the runner’s propulsion moving forward, otherwise the extension of the foot/ankle, knee, and hip (triple extension) would create a vertical force (we want the runner to move forward, not up).
The anterior pelvic tilt demonstrates a very interesting kinetic chain relationship. When watching runners going down a hill, it is common to see some runners whose energy seems to be directed more vertically than forward (they are bouncing down the trail). This common phenomena is often caused by lack of anterior pelvic tilt due to tight hamstrings, or due to a strength imbalance between the hamstrings and the quadriceps (9). Often, the runner has weak hamstrings compared to their quadriceps strength. Ideally, hamstring to quadriceps ratio should be as close to 1:1 as possible.
Elastic Recoil....It's Important
A runner stores energy from foot contact to Mid-Stance, they then release this energy from Mid-Stance to Take-Off. The concept of elastic recoil is incredibly important, especially when we consider that the efficiency of elastic recoil is greatly determined by the quality of our musculoskeletal structures. By quality, I refer to the capacity of our soft-tissues to store and release energy. Tight, rigid, restricted soft-tissues and joints do not have a good capacity for generating good elastic recoil.
Hands-on therapy, self-myofascial release, stretching, and the use of functional strengthening exercises all play an important role in helping to reach your maximum running potential!
THE SWING PHASE OF GAIT
The Swing Phase also has three distinct sub-phases:
The Swing Phase of gait begins at toe-off and ends on heel-strike. This phase consumes about 40% of the total gait cycle.
The primary function of the Swing Phase is to provide ground clearance for the foot (by Mid Swing), and to position the legs in a way that allows the supporting muscles to dissipate impact forces upon ground impact (10).
Initial Swing: Swing Phase
Initial Swing begins when the foot leaves the ground upon toe off (when you start to fly). At any time one, one foot is off the ground and in a state of recovery. If fact, there is one point in the gait cycle where both feet are off the ground. This is called the “Double Float Phase” of gait. Running velocity greatly affects the length of this phase (the faster you go, the longer you fly).
Mid Swing: Swing Phase
The Mid Swing (Forward Swing phase) increases the runner’s forward velocity. It achieves this through the actions of forward pelvis rotation combined with hip and knee flexion. Any physical restrictions in the muscles involved in pelvic motion or hip or knee flexion will drastically reduce the fluidity of this motion.
Terminal Swing: Swing Phase
Terminal Swing stage begins when the runner’s hip reaches a position of maximum flexion. Knee flexion helps to promote movement of the lower extremity. The forward motion of the foot coming down (before foot strike) is controlled by the hamstring muscles. This phase ends when the runner's foot makes contact with the ground beginning a new cycle.
The primary function of the hamstrings during the Swing Phase of gait is to eccentrically control knee extension. (Always keep mind that every muscle has a concentric and eccentric function.)
Remember that each action involves multiple structures (muscle, ligaments, tendons, fascia, joints, and a multitude of neurological structures.) Gait is a complex action and every structure plays an important role.
CONCLUSION - WE ARE DESIGNED TO RUN - THE HUMAN GAIT CYCLE
Human evolution has given us an incredible gait cycle, it is designed for optimal shock absorption and propulsion.
Running efficiency is all about improving energy conservation - the less energy we waste, the greater the performance, and the fewer injuries we develop.
There is a direct correlation between the quality of soft-tissues, joint integrity, and how well your gait cycle functions.
If the runner has muscle imbalances, myofascial restrictions, or joint dysfunction - then optimum performance will not be achieved.
In upcoming blogs, I will go over the various anatomical structures that are involved, and show how even minor tweaks can make a huge difference in improving running efficiency and injury prevention.
It's Important....Know the Gait Cycle!
Practitioners with a good understanding of the gait cycle are better able to formulate treatment and training programs, and customize treatments to address the specific needs of each individual runner. Patients should seek out these practitioners to achieve optimum results in injury prevention, injury treatment, and in improving sports performance.
Bottom line - You Are Designed to Run. It took us over four million years of evolution to develop this incredible bipedal locomotion system, so you might as well do your best to keep it functioning at an optimum level.
Until Next Time
Dr. Brian Abelson
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DR. BRIAN ABELSON DC.
Running has a passion for Dr. Abelson - he is a runner and triathlete himself and has competed in numerous marathons and Ironman events over the last 40 years.
Dr. Abelson is the owner of Kinetic Health, a partner in BKAT Motion Specific Release, and a partner in Rowan Tree Books.
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