Run smart! Part 2. The biomechanics of running. How to improve performance and reduce injury

Running is an accessible, easy way of staying fit and healthy and has multiple health benefits

By working on our running technique we can significantly reduce our risk of injury

This article discusses the basics of running biomechanics and provides top tips for your own training

The biomechanics of running

In Run Smart Part 1, we looked at ways in which we can vary our running training. In this newsletter, we explore running technique and discuss important parameters to be aware of. We also discuss how we can adjust our technique to get even more out of our running and remain injury-free.

Running parameters

Most of us would agree that running is a fairly natural body movement and would never have been taught how to run. However, learning how to run with good form and technique is just as important as it would be for any other sport. We look at some of the main running parameters that we should all know about.

Cadence

Our running cadence is the Total Number of Steps per Minute (sometimes referred to step rate or stride frequency). We can easily calculate this by;

  1. Counting the number of foot contacts of one leg in a minute when running and then multiplying by 2
  2. Using wearable technology to calculate this for us as we run
  3. Running to a predetermined cadence set by a metronome or song

The biggest factor affecting our running cadence is speed. As we speed up our cadence will also increase and vice versa. At faster speeds however, it is possible to increase our cadence without changing our speed. The length of our legs will also affect our cadence, those of us with shorter legs requiring a high cadence to match the speed of someone with much longer legs.

What is the optimal running cadence?

Runners will often ask, what is the best running cadence? In reality, cadence should vary depending on the type of running session and its intensity. For example, if you are going for a recovery or steady state run, you may aim for a slightly lower cadence than if you are doing interval training or tempo running. 

Lots of runners and coaches often quote a cadence of 180 beats per minute as the golden figure to achieve, but there isn’t any real scientific evidence to back this up. It is true however, aiming for a higher cadence does usually require better running technique and form. There is evidence to show that higher cadences reduce impact stress on the body.

Should I change my cadence?

If you are thinking about changing your cadence, make sure you understand why. Is it to help recover from an injury or prevent injury in the first place? Or is it to improve performance? It is always good to chat this through with a professional e.g. running coach and/or rehab practitioner.

If you are looking to increase your cadence, research suggests increasing your running cadence by no more than 5-10% at a time. Running to a metronome beat or music at a set cadence is an easy way of facilitating this. As we will discus, shorter quicker strides will have you landing your foot closer to beneath your hips and therefore your centre of mass. This helps to reduce impact and braking forces your body has to deal with every stride.

Remember that certain injuries such as tendinitis can actually be caused by having too high a cadence. It is always worth getting a formal running assessment prior to making a change. 

Stride Length

Stride length during running is the distance covered when you take two steps, one with each foot (step length is the distance covered when only one step is taken). It can be calculated in a few ways.

  1. Calculating this by yourself is a little tricky but can be done with piece of chalk and a measuring tape. Use the tape measure and the mark of a specific distance, such as 20 feet. Start running into your natural pace and speed about 10 feet before one of the marks. When you hit the first mark, start counting your strides, stopping your count when you hit the second mark.
    Distance in feet/number of strides = stride length (feet)
  2. Using wearable technology to calculate this for us as we run. Usually we would need a chest strap monitor to calculate this.

Overstriding

During the running cycle, as the foot strikes the floor, a Ground Reaction Force (GRF) is distributed through the body. The foot strike position (initial contact), should ideally be as close to the body’s Center of Mass (COM) as possible so this force is distributed more efficiently.

When foot lands in front of us and the shin is angled too far forward, this is known as Overstriding. The wider the shin angle (inclination angle), greater the distance between the body’s Centre of Mass and the point of foot strike. This causes more impact on the joints and muscles, reduces running efficiency and increases stress to the shin, knee, hip and lower back.

overstriding Run smart! Part 2. The biomechanics of running. How to improve performance and reduce injury

Why do we Overstride?

Overstriding can be a result of either a physical limitation in the runner’s body or a technical fault like low cadence. Some of the common causes are:

  • Limited hip extension (tight hip flexors) leading to excessive anterior pelvic tilt. Excessive anterior pelvic tilt forces runners to use overstepping as a way to get the big stride
  • Weak hamstrings or glutes limits the knee drive, causing the runner to depend on shins to reach forward
  • Reduced forward lean also forces runners to reach forward by extending the shin forward. Reduced forward lean is often due to lack of strength in hip and trunk extensors
  • Runners with lower cadence often reach forward with shin and strike the ground much ahead of COM

If we do tend to overstride, research has shown there is an associated higher risk of injury. This is due to;

  • Impact forces being much higher on tibia, ankle, knee and hip joints when we land. Landing the foot strike further from the COM, produces more torque (Torque = Force x Distance) on joints.
  • More stress on joints leads to injuries such as tibial stress fractures, plantar fasciitis, Patellofemoral Pain Syndrome (PFPS/Runner’s knee) and other joint injuries.
  • Overstriding also increases braking force, which affects the running performance. The excessive braking force also causes Achilles injuries.

The easiest way of changing our stride length is by altering our cadence. If we increase our cadence our stride length will naturally decrease. However, we can also positively influence our stride length through small technical changes, which we shall discuss later. 

Footstrike

A runners footstrike refers to which part of the foot makes initial contact with the ground when running. This is usually categorised into 3 separate patterns;

  1. Heel-striking
  2. Midfoot
  3. Forefoot.

In reality these patterns exist along a continuum and our pattern of running can even change depending on how fasting we are running.  

footstrike Run smart! Part 2. The biomechanics of running. How to improve performance and reduce injury

Heel-striking is arguably the most common footstrike pattern amongst runners. There’s no clear advantage of switching from a heelstrike to a forefoot strike pattern and some evidence suggests heelstrike t may even be more efficient, especially in endurance events. Footstrike should be viewed as a continuum, rather than three separate, fixed patterns. We may move along this continuum as speed increases or by altering stride length and cadence.

Which footstrike pattern is more likely to cause injury?

Each footstrike pattern has pros and cons and affects load at the hip, knee, calf and foot. Large changes in footstrike that are made too quickly can increase load on different tissues and potentially lead to injury. However, certain injuries are more common if we tend to run at extreme ends of the scale for prolonged periods of time. A few of the common injuries are listed below.

Excessive Heel-striking –  This may lead to conditions such as;

  • Plantar fasciitis
  • Heel bone stress
  • Shin splints.

Excessive Forefoot-striking – This may lead to conditions such as;

  • Metatarsal stress fracture
  • Metatarsalgia
  • Achilles tendinitis

Footstrike position can easily be determined by filming yourself running a treadmill at various speeds. However, by having a formal running assessment, this can be analysed in more detail.

How do I know if I could improve my running technique?

If you are able to run to your desired performance level and remain injury free, then that’s great! Chances are you do not need to change much around your running form or technique. However, for those looking to improve performance or are injury prone, it is worth having a further look to see how small, subtle changes to your running technique can make a big difference. 

The following are some simple indicators that may help indicate poor running form;

  • Very low cadence (<165) even at faster paces
  • Excessive rear foot or forefoot strike
  • Excessive overstriding

Beyond these, the best way to identify poor running form is to get a formal gait analysis where more detail can be determined. This may include;

  • Shin & foot inclination angles
  • Knee flexion angle
  • Parameters such as vertical, braking force at initial contact
  • Ground contact times

Some simple running tips and tricks

Below are some simple tips to help improve your running form; 

  • Increasing cadence: This is an effective method to reduce overstriding. Quick turnover of legs helps the foot to land closer to the COM. Increased cadence reduces vertical and braking forces, and load on the joints.
  • Better hip extension of rear leg: This requires adequate flexibility in the hip flexors, and also better engagement of glutes, so runners can extend hip and knee fully and achieve a longer push off. A longer push-off puts us in a better position to get a good stride, without resorting to overstriding.
  • Higher knee drive in the front leg: Good forward knee drive patterns require sufficient strength throughout the hips to drive the knees higher and in a linear path. This will also set the leg and foot up for an ideal foot strike position.
  • Use these cues while running: Follow these cues while running to avoid overstriding – ‘get feet off ground quickly’, ‘run on ice’, and ‘high knees and low ankles’.

Hope the above tips are useful. For more detail please contact us for a formal gait analysis and consultation. 

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