Understanding Ground Contact Time Imbalance While Running

Ground contact time, often just referred to as GCT, is how long each foot stays in contact with the ground during a run. Ideally, both feet should spend an equal amount of time on the ground. This is the foundation of a symmetrical and efficient gait. But sometimes, ground time is unevenly distributed between your left and right feet, which leads to a ground contact time imbalance.

GCT imbalances can be caused by muscle imbalances, injuries, or poor running form. They may increase the risk of injury., which in turn interrupts consistency and progress. More than that, research suggests that imbalance can result in less efficient running form.

In this article, we’ll explore the concept of ground contact time imbalance. We’ll discuss its potential effects on your running, and how to address it. I will share my personal experience in working to correct ground contact time imbalances. This insight can help you become a better informed, and ultimately a more resilient runner.

Why is GCT important?

An even ground contact time is crucial for maintaining a balanced and efficient running form. It ensures that both sides of your body are working in harmony. Imbalances can lead to increased stress on muscles, joints, and ligaments. Over time, this can result in injuries or reduced performance.

A recent research study found that ground contact time imbalances can lead to reduced running efficiency. ¹Joubert, et al., 2020, International Journal of Exercise Science The results indicate that a 1% increase in GCT imbalance leads to a 3.7% increase in metabolic cost.

Said another way, that means you have to work harder to maintain a certain pace if the ground contact time is not evenly distributed between your right and left legs. Which means that if you can correct your imbalance, you can run faster.

Identifying Ground Contact Time Imbalance

It can be challenging to detect GCT imbalances without the help of technology. However, some common signs include:

• Uneven wear on your running shoes
• Consistent injuries or pain on one side of the body
• Feeling “off-balance” or favouring one leg during your runs

Using Technology to Measure GCT

Gait analysis systems and wearable devices can help measure ground contact time. Some running watches and foot pods provide GCT data, allowing you to track and monitor any imbalances. 

A newer Garmin running watch paired with a capable heart rate strap will measure your ground contact time. After your run, you can look at the details in the Garmin Connect app on your phone, or on the web. Here is how they define this metric, and the different buckets they use to categorise your data:

“Ground Contact Time Balance measures your symmetry as you run by monitoring the balance between your left and right foot ground contact time (GCT). It is always displayed as a percentage greater than 50% with an arrow to the left or right to show which foot is on the ground longer.

For most people, a more symmetrical running form is preferable. Color gauges on Garmin watches and Garmin Connect show how balanced you are compared to other runners. Many runners report that GCT balance tends to deviate farther from 50/50 when they run up or down hills, when they do speed work or when they are fatigued. Some runners also notice that injuries are reflected in greater imbalance.

The color zones in the table below show the percentage of runners that occupy each zone, as well as the ground contact time balance ranges for each zone. They’re useful for comparing your performance to other runners.”

Garmin Connect description of Ground Contact Time

The screenshot below shows this data from one of my recent runs. I’m sure you’ll understand why I started researching ground contact time imbalances after seeing this. 

The imbalance has been present since I started running more than five years ago. I’ve tried a variety of measures to correct it, and I will share my experiences in the following section.

Strategies for Correcting Ground Contact Time Imbalance

Muscle imbalances can significantly contribute to GCT issues. When certain muscles are stronger or more flexible than others, it may lead to uneven distribution of force during running. This can cause one foot to spend more time on the ground than the other.

While I’ve always had a certain imbalance in my gait, it was exacerbated by a knee injury. Running on a painful knee caused me to change my form ever so slightly, in an attempt to alleviate the pain. Favouring my stronger side, this in turn aggravated my existing muscle imbalance.

Targeted Strength Exercises

To restore balance and reduce the risk of injury, it’s essential to target weak or tight muscles with specific exercises.

• Single-leg exercises: By isolating one leg at a time, you can identify and address strength differences between the legs. Exercises like lunges, step-ups, and single-leg deadlifts help develop balanced lower body strength and stability. I’ve found this to be the most effective way of improving my perceived balance while running.
• Core strengthening exercises: A strong core helps maintain proper running posture, reduces energy waste, and ensures a symmetrical gait. Incorporate exercises such as planks, leg raises, and Russian twists into your routine to build a solid foundation for running.
• Hip mobility exercises: Tight hips can cause imbalances in your stride, contributing to GCT discrepancies. Improve hip mobility and flexibility with exercises like hip circles, clamshells, and leg swings. Check out this extensive article by physiotherapist Jarlo Ilano for some great tips on how to improve your hip mobility.

To determine which exercises are most relevant for you, consider the following:

1. Pay attention to any signs of muscle imbalances, such as uneven wear on your running shoes, consistent pain on one side, or feeling “off-balance” during runs. 
2. Conduct self-assessments, such as comparing the ease of performing single-leg exercises on each side. If you notice a significant difference in strength or stability, focus on the weaker side to restore balance.
3. Monitor your progress by tracking changes in muscle strength, flexibility, and overall running performance. If you notice improvements in these areas, it’s a sign that the exercises you’re performing are beneficial.

Remember, it’s crucial to be consistent and patient when addressing muscle imbalances. Gradually incorporate these exercises into your training routine, and allow time for your body to adapt and develop balanced strength and flexibility. We’re talking months, plural, as opposed to days and weeks.

As mentioned, single-leg exercises have been very helpful to me. When I do them consistently over months, I notice that my strength imbalances even out when doing the exercises. What’s more, I find that I feel stronger, and more balanced while running.

Improving Running Form

Addressing ground contact time imbalance also requires focusing on your running form. Proper running mechanics help distribute force evenly across both legs and reduce the risk of injury. Here are some key aspects to consider:

1. Maintaining an upright posture: Running with a tall, upright posture allows for better alignment of the spine and pelvis. This can help promote a more symmetrical gait and reduce the likelihood of ground contact time imbalances. Focus on keeping your head up, chest open, and shoulders relaxed.
2. Landing softly on the midfoot: Research suggests that a midfoot strike pattern may reduce the risk of running-related injuries compared to a rearfoot (heel) strike pattern. ²Lieberman et al., 2010, Nature Aim for a gentle midfoot landing, which can help distribute forces evenly and promote a balanced gait.
3. Aim for a cadence of 170-190 steps per minute: A higher cadence (steps per minute) can help reduce ground contact time and encourage a more balanced gait. Studies have shown that increasing cadence can reduce impact forces and the risk of injury. ³Heiderscheit et al., 2011, Medicine & Science in Sports & Exercise
4. Arm swing and overall body coordination: Your arm swing can significantly affect your leg movement and overall running form. Try to keep your elbows bent at a 90-degree angle and swing your arms forward and backward in sync with your opposite leg. This helps maintain a balanced, rhythmic stride and can contribute to reducing ground contact time imbalances.
5. Regularly evaluating your running form: As you make changes to your running form, it’s essential to regularly evaluate your progress. You can do this by recording yourself running and analysing your form or working with a coach or sports therapist. This will help ensure you’re making the desired improvements and maintaining a balanced, efficient gait.

Be Patient and Focus on One Element at a Time

Focusing on these aspects of your running form can help correct ground contact time imbalances. The result can be that you’re less prone to injuries, and that your overall running efficiency improves.

However, it is important to remember that becoming stronger and improving your running form takes time. Be patient as you aim to improve these aspects of your running. Furthermore, don’t try to implement all things at once.

In particular when it comes to running form, it is important to focus on one cue at a time. Don’t aim to improve your posture, arm swing, and cadence simultaneously. This is a mistake I’ve personally made. More than once!

The result is that I’ve ended up thinking about too many things at a time, failing to properly focus on any single one of them. And, as if to highlight my own silliness, I’ve done this while on a long run. The result was a body that ached all over, and I couldn’t train properly for weeks.

Work on one aspect until it becomes second nature, and you’ve internalised the change. If at any point you notice that the changes to your form are causing pain during a run due to unfamiliar loading patterns, you need to be more gradual. In this case, stick to short easy runs at first.

Summary

After working to improve my ground contact time imbalance for years, I’ve got a clear idea of what’s worked for me and what didn’t. Regular strength training to address muscle strength imbalances is paramount. As soon as I start slacking with strength training, my old imbalances reappear.

I’ve also found that no matter what measures I do, I haven’t been able to adopt a perfectly balanced running form for my easy runs. Trying to focus on being more balanced while running simply makes matters worse.

What’s important, however, is that as long as I remain diligent about keeping my muscle strength balanced, my form is fairly balanced while I’m running faster. 

I say this to highlight the importance of individual considerations before making an effort to change things. If you’re not struggling with injuries, and your fitness is progressing well, and you’re not experiencing any discomfort while running, you don’t need to get caught up in the numbers. Don’t try to fix what ain’t broke!

That said, if you’re experiencing any of these challenges, it might be worthwhile to look at ground contact time for signs of what you can improve. Addressing muscle imbalances and refining your running form are two essential strategies for correcting ground contact time imbalances.

By implementing these approaches, you can improve your running performance. And, potentially reduce the risk of injury, and enjoy a more balanced, efficient, and enjoyable running experience.