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Running – some of us love it, some hate it, and some could go either way.
Some of us want to run a marathon and others to be able to run after our kids.
No matter your goal, it’s important to ensure that the supporting muscles in your lower extremities are well maintained and strong and that your running biomechanics are in check.
Running Biomechanics and the Gait Cycle
Before you dive into an exercise regime for your running, you need to understand running biomechanics.
Running starts with the gait cycle.
Gait can be measured at many different points, but we’re going to look at the biomechanical path from heel strike to heel strike.
That starts with what occurs in the different parts of your leg as your foot first hits the ground.
Next, we’ll look at how the forces are transferred when you pick it back up.
Finally, we’ll examine what happens before it hits the ground again.
The gait cycle can be broken into two major phases with different movement patterns.
The Stance Phase
The first phase is called the stance phase.
This phase occurs when one foot is in contact with the ground
This can be divided into three sub-phases.
The first of these is referred to as ‘initial contact.’
As discussed, it represents the first heel strike and marks the beginning of the gait cycle.
During initial contact, the foot contacts the ground beneath it for a brief moment before the next phase, mid-stance, begins.
During mid-stance, the entire weight of your body is placed temporarily on the foot that is contacting the ground.
This strength and stability of the intrinsic muscles within your foot during this phase are crucial because it is the point at which the forces transfer to guide the body into the next phase, take off.
The take-off phase is also called ‘toe-off’ because, during mid-stance, the foot has successfully transferred the forces absorbed during initial contact.
This force transfer is rapid and provides the energy required for this final phase, giving the foot and lower limb propulsive energy to enter the next larger phase of the gait cycle.
The Swing Phase
The second phase of the gait cycle is called the swing phase.
During this phase, one foot swings freely in the air, and while this phase occurs on one foot, the stance phase occurs on the opposite foot.
The swing phase can also be broken down further into three subphases.
The first phase is the initial swing.
The initial swing phase occurs immediately after the take-off phase powerfully pushes off of the ground and takes place while the foot and leg extend back behind the body.
This phase ends when the hip has reached its full extension, and the next phase, called mid-swing, begins.
During this phase, the hip starts to move in the opposite direction, flexing forward, and the knee follows suit.
It’s helpful to think of this phase as a whip-like motion.
Before the “crack” of a whip, it recoils and builds up energy to expend through to the very end of the actual whip.
When running, the legs operate similarly.
The hip and knee flex during the mid-swing phase and begin to build up energy to make the following phases explosive.
The terminal swing phase follows this as the body prepares to transfer its built-up forces from mid-swing to the next phase where the heel strike occurs, initial contact.
And so the cycle continues, generating energy and transferring the energy, ultimately allowing our body to move forward in movements such as walking, jogging, and running!
Muscles Involved in the Gait Cycle
Now that we understand the biomechanics of gait, we can take one step further in understanding the muscles involved in each phase.
We’ll continue discussing the gait cycle from heel strike to heel strike.
The iliopsoas muscle is the strongest hip flexor and plays an important role in maintaining the strength and integrity of the hip and lower back.
Also known as the buttock muscles. This muscle group includes the gluteus maximus, gluteus medius, gluteus minimus and tensor fasciae latae muscles.
This muscle group includes the semitendinosus, semimembranosus, and biceps femoris muscles which act to flex the knee.
Also known as the quadriceps femoris muscle which acts as both a hip flexor and a knee extensor.
Also known as the tibialis anticus, this muscle is situated in front of the tibia (near the shin) and acts to flex the foot backward.
Also known as the gastrocnemius and soleus, these muscles allow you to propel, rotate, and flex your foot and lock your knee.
The Stance Phase
Different muscles act in unique ways during each sub-phase of the more extensive stance phase, initial contact, mid-stance, and take-off.
In the initial contact, muscles including the gluteal muscles, hamstrings, quadriceps, and tibialis anterior are active.
During this phase, the hip begins extending behind the body, the quadriceps work to stabilize the knee, and the tibialis anterior begins to help the foot absorb forces.
During the mid-stance phase, most of these muscles continue their work.
The gluteal muscles remain active in extending the hip, the hamstrings begin to engage further and initiate knee flexion.
The tibialis anterior continues to work in mitigating the loading response.
The last phase, take off, is the culmination of these previous steps.
The gluteal muscles and hamstrings have been fully engaged, and the quadriceps muscle is stretched with the hip and knee extended behind the body.
Most importantly, the calf muscles (gastrocnemius and soleus) work to flex the foot downward and propel forward.
The Swing Phase
During the swing phase, the muscles which became fully stretched during the stance phase now take over.
The initial swing begins immediately after taking off when the iliopsoas muscle begins to flex the hip forward.
The quadricep muscles play a role in flexing the hip forward here, and the anterior tibialis muscle remains active to keep the ankle in plantar flexion.
The next phase, mid-swing, continues to engage the iliopsoas to flex the hip forward and the hamstrings to flex the knee up.
As the hip and knee come forward in mid-swing to prepare for the next phase, the knee begins to extend back down to the ground to bring the foot closer to the earth.
The final phase, terminal swing, engages the muscles involved in the mid-swing phase and the initial contact phase as the body prepares for its next heel strike.
This means that the gluteal muscles, hamstrings, quadriceps, and tibialis anterior muscles are all engaged to provide maximum strength and stability to the lower body’s joints as it begins to bear weight.
How to Improve Running Biomechanics
So what’s next now that we understand how the biomechanics of running work?
We want to strengthen the muscles to improve performance and prevent injury.
During running, the body is constantly absorbing and transferring forces.
Much like a car’s engine, if something is even slightly off, it can cause major problems over time if it isn’t addressed promptly.
When thinking about strengthening muscles to improve running, you want to focus on all of the muscles involved in the gait cycle that help to stabilize the important joints in the lower extremity, such as the hip, knee, and ankle.
These muscles include the gluteal, iliopsoas, hamstrings, quadriceps, and tibialis anterior.
Generally speaking, strengthening these muscles will help prevent injury and provide a strong, stable base for your body to work from.
Past training for general strength, many running athletes want to train to be fast and explosive during the take-off phase of the stance cycle.
This phase is what provides the propulsive force to move the body forward, so the stronger and more explosive it is, the better.
When assessing the involved muscles in the gait cycle, you may be prescribed further training exercises for the calf muscles, gluteal muscles, and hamstrings to train them in this way.
To improve the quality of your running performance, you’ll want to be assessed by a fitness professional, coach, or doctor who specializes in biomechanics, like a chiropractor or physical therapist.
These professionals can help address any deficits you may have in strength and provide you with unique exercises to improve your performance and running biomechanics.