May 23, 2017

Ground Contact Time

What is a good ground contact time for running?

The runners who lead endurance races have more in common than just the ability to maintain fast paces for long periods of time, they also spend less time on the ground and more time in flight. That's why a somewhat obscure metric called ground contact time (GCT) is important to track and analyze; it plays a major role in optimizing your running efficiency and form. 

GCT is the measurement of the amount of time you are in contact with the ground during strides when running, from foot-strike to toe-off. It's closely tied to cadence (the number of steps you take per minute) and vertical oscillation (the height of your vertical bounce). Generally, when you train to improve in one of these areas, it impacts the other two.

A screenshot of SportTracks fitness tracking software showing running dynamics metrics

SportTracks enables you to easily compare GCT with other metrics

Spending less time on the ground and more time in the air helps you increase your speed by reducing the braking effect caused by over striding. When training to improve your ground contact time, you need to keep your vertical oscillation (VO) as low as possible, because excessive bouncing wastes energy moving the weight of your body vertically.

What’s a good ground contact time for running?

Your GCT is a product of your specific physique and abilities. Because this metric is so personal, it only makes sense to compare you to you. It's fine to familiarize yourself with the target numbers, but it's more important to assess your personal capabilities, and whether or not these training practices are giving you more speed.

As a baseline, your GCT should be below 300 milliseconds, however, fast runners often have significantly lower numbers in the 175 - 200 millisecond range. If your GCT is already well under 300, it's still totally worthwhile to train to shorten it, because even a small amount of improvement can make a significant impact on your times in longer races.

How can I improve my ground contact time?

Training to shorten your ground contact time requires a combination of speed work, strength training, and plyometrics. Increased speed brings higher cadences and more flight time, while strength training and plyometrics will increase leg stiffness, so you reuse the energy from impact for propulsion instead of absorbing it. Incorporate strides and hill sprints into your weekly training, and concentrate on building strength in your hip flexors and glutes. 

Many of the same training drills that are used to improve speed are used to shorten GCT. The faster you go, the shorter your GCT will typically be. However, if you're not tracking and analyzing this metric, you won't be able to determine what's working and what isn't.

How can I track GCT?

The Stryd running power meter and the Garmin Running Dynamics Pod

Special sensors are required to track GCT and VO. Garmin refers to these metrics as Running Dynamics, and you need specific combinations of their hardware to capture this data. The modules with this capability are the HRM-Run and HRM-Tri, both of which are chest-worn heart rate monitors, and the Running Dynamics Pod, which is a small device that clips to the back of your running shorts.

Here are Garmin's solutions for tracking ground contact time:

  HRM-Run   HRM-Tri   RD Pod
Forerunner 945 or or
Forerunner 935 or or
Forerunner 920XT or    
Forerunner 245 or   or
Forerunner 735XT or or
Forerunner 645 or or
Forerunner 630        
Forerunner 620        
fēnix 6, 6S, 6X or or
fēnix 5, 5S, 5X or or
fēnix Chronos or or
fēnix 3, 3 HR or    
fēnix 2        

Users of the Sunnto 5 and 9, Spartan, and Ambit 2 and 3 can track these metrics with the Stryd footpod. The same applies to the Polar M400, M430, V800, Vantage V and M. Stryd provides a variety of running power metrics in addition to GCT and VO, plus it has the most accurate pace and distance tracking available. It's also compatible with the Apple Watch Series 2, 3, 4, and 5.

Garmin users can use the Stryd footpod as well, which is a nice solution because it brings GCT and VO tracking to the following watches that previously lacked this ability: the Forerunner 230 and 235, 310XT, 910XT, Vivoactive, and Vivoactive HR.

The ability to easily track GCT first arrived in late 2013, when Garmin announced the Forerunner 620 GPS watch and the HRM-Run heart rate monitor. Just a few months later, SportTracks added support for these new metrics (VO was added as well). It was the first major fitness tracking platform to do so, and many other well-known platforms still lack this capability.

It wasn't that long ago that GCT training was something that happened in the dark. Experts had determined that it was an important part of running efficiency, but there were no sensors that could track it. With the advent of new training devices and platforms like SportTracks, you can now target your workouts to optimize your GCT and quickly determine if they're making a difference.

Editors Note: This post was updated in October 2019 to add more compatible watch models. It's also worth mentioning that many well-known fitness platforms still do not support GCT.

Comments

The Milestone Pod also tracks GCT, but not VO.
And, at this time, it's not real-time and has no way to export the data to other platforms (Like ST), except totals per workout .