By Steph Davies, Liam Goode and Glynn Davies
Chartered Physiotherapists
Introduction
The biomechanics of running is a vast and specialist subject that frequently changes with emerging research and new trends, all aimed at improving our understanding of the most efficient way to run. Every runner is likely to have very individual needs when it comes to biomechanics, but here are a few of the basic principles about what happens to the body when you run.
Phases of Running
Initial contact = your foot hits the ground – this is the main source of impact during running
Mid-stance phase = your leg takes the weight of your body and prepares to push off
Push-off / Toe-off phase = you push off to propel yourself forward
Swing phase = your leg swings through the air to prepare for the next step
Foot & Ankle
The foot needs a degree of pronation to absorb the weight of the body during impact, and supination to propel it forwards. However, excessive movement can lead to pain. This can be due to problems within the foot itself or problems from joints further up.
The ankle joint plays a pivotal role in moving the body forwards with associated muscles providing stability and control. To help prevent injury, it is important to have efficient muscle control around the joint.
Calf
The main muscles of the calf are gastrocnemius and soleus. These provide power and endurance to enable you to repeatedly push off from the ground. Weakness, tightness or pain in these muscles can affect the way your foot, ankle and even your knee move as you run.
Knee
The knee is a hinge joint that absorbs up to four times your body weight with each stride. It relies on the surrounding quadriceps, hamstrings and calf muscles to provide power for movement, shock absorption and stability during landing and push-off. The knee is a common area of injury amongst runners as it is vulnerable to problems at the hip above and the foot below.
Quadriceps
The quadriceps muscles at the front of the thigh help to absorb the impact associated with running. They also powerfully contract and to propel you forwards into your stride by straightening the knee.
Hamstrings
The hamstring muscles are at the back of your thigh, and their main role is to prevent the knee from over-straightening. The bigger your stride length the harder the hamstrings have to work to do this, hence why hamstrings are more frequently strained during sprinting than jogging. The hamstrings also team up with the gluteal muscles in the buttocks to help propel you forward by extending the hip joint.
Gluteals
There are three main gluteal muscles; gluteus maximus, medius and minimus. Gluteus maximus is the most powerful and helps to propel you forwards in by driving your leg backwards through the mid-stance phase into push-off. Gluteus medius and minimus play an important and often underestimated role in running, controlling rotation at the hip and maintaining good joint alignment through the rest of the body. Many running related injuries are a result of poor control of the gluteus medius and minimus muscles.
Core
‘Core’ muscles in this sense refer to all of the abdominals, obliques and spinal muscles. In running, they are required to control the upper body and provide a stable base from which your arms and legs can move freely. A well balanced ‘core’ will allow efficient and fluid movement without any unnecessary effort.
Arms
For endurance running, the arms should be relaxed and the shoulders should have adequate range of movement on both sides to swing equally. Most sources advocate elbows to be relaxed and flexed between 85-100 degrees. Any restriction in the range of movement of one arm compared to the other is likely to have a knock on effect on the rest of the body, possibly causing problems in the spine and pelvis or overuse of one leg compared to the other.