Episode 3: GPS, Pace, Indoor Running, Treadmill Training

Have you ever run a race & noticed that your watch didn’t match the mile markers or give you the same distance as someone else who ran the race?

Which is more reliable – the treadmill or your watch’s indoor running mode?

In episode 3 of The Art and Science of Running Podcast​, Malc Kent​ & Jacob Puzey​ discuss GPS, indoor running metrics, treadmill training, race course certification & other running metrics and technologies.

Listen, subscribe, rate & review the show at Apple Podcasts​, Spotify​, Stitcher​ or wherever you listen to podcasts!

In episode 2, we discussed some of the work we’ve done as coaches as well as observing groups and other coaches such as Patrick Sang of the NN Running Team in Kenya.

Much of coaching we do now is done remotely via Runfisx and Peak Run Performance.

However, many of the athletes with whom we work train with others. Running is a social sport at it’s core.

In episode 2 we also discussed some of the work Malc has done with the development of wearable technologies / devices. These devices are used to measure a whole host of metrics.

Given that Malc is responsible for developing the algorithms and technologies behind many of these devices, Jacob asked Malc some of the most frequently asked questions he receives as a coach, race director, and athlete.

What is GPS and how does it work?

Malc explains that there are multiple satellites orbiting the planet. GPS devices regularly ping these satellites to get feedback about one’s location. There is a two way relationship between the satellite and device. GPS can be accurate as a remote means of telling where someone is. One can also be moving and get relatively accurate data as to where you are when moving.

Wearables are generally limited by batteries. The biggest problem with wearables is how to conserve battery. GPS hammers battery life. It becomes a question of how often do you sample the GPS location vs. how large do you want the device to be and how long can the battery last?

There is a tradeoff, as is always the case with wearables, between do you want an accurate location all the time or do you want a longer battery life?

Battery life has gotten better, but it is still a limiting factor.

Another issue with GPS is pace reading in real time. For example, you could have an individual runner running 4:00 per/km however, you’ll likely have a fluctuation in accuracy of pace coming off throughout the workout because you may or may not have multiple satellites to interact with at any given time – especially if running on trails or in an area obscured by shade or buildings. If you are looking for accurate pace feedback, use average pace at regular intervals rather than looking down at your watch as you run.

You can measure pace locally with an accelerometer with greater accuracy than GPS. These devices require less power / battery, however, such devices require better calibration. Accelerometers can give greater accuracy without the need of satellites.

What about if you are running inside on an indoor track or treadmill? How does that work?

Depending on the construction materials used in the building, you are likely going to have trouble picking up GPS signals if / when running indoors.

Why is there variability between advertised distance and what watch reads during and after a race?

Not everyone runs the tangents. For example, some may run long around the corners or at aid stations.

Newer watches should have firmware algorithms with automatic recalibration when stationary, however, hardware and firmware algorithms are not all equal. There will be natural differences between various brands and generation of brands

As a race director, Jacob has dealt with measuring and certifying distances for road races. These certification processes often do not include GPS, but rather more traditional means of measuring such as measuring wheels and pedometers.

For best results, be sure to locate a GPS signal on your watch well before starting the run.

What is being measured in Indoor Running mode?

Malc recalls that the idea of measuring pace with a watch before foot pods has been around for awhile.

Accelerometers can break out where foot contact begins and ends and can distinguish between one step and the other. However, when on the wrist it can be challenging when determining when arm swing starts and the other begins.

Malc explains that most algorithms are inherently flawed because they only know what they are told to know. There will always be people out there who have weird form or different arms swings which makes the algorithms and the readings less accurate.

Unless there is a reason not to trust the treadmill, the treadmill reading should be trusted over most wrist based technologies.

A standard treadmill has cylinders in the front and back which allows the treadmill to measure distance and pace with strong accuracy based on the circumference of the cylinders.

Always trust treadmill first when there is a discrepancy.

If you get same reading from your watch as the treadmill then you must have the same arms swing as the algorithm was designed to track.

Treadmill training:

Should you increase the incline to get accurate readings?

Not necessarily.

Is it better to train indoors vs. outdoors?

When you know you have an injury history, training on a treadmill can be beneficial when coming back so that you can test yourself and stop immediately.

On the flip side, training on a treadmill can be monotonous, with not enough variation which can lead to overuse injuries – particularly runner’s knee.

Treadmills can be particularly beneficial when doing fixed paced workouts or continuous uphills so that you can control the angle.

Training on a treadmill also allows you to control more variables as well as train the mind for the monotony of a long race.  Gain mental fortitude, be bored, and learn to lock into autopilot by training on a treadmill.

Treadmills can be beneficial for simulating race terrain – specifically long hills.

Treadmills can be beneficial because they save travel time to and from trails.

However, the lack of variation can cause overuse injuries.

Some apps such as Zwift and iFit can help simulate a more authentic setting.

What are the pros and cons of doing gait analysis on a treadmill vs. outside a clinic?

Doing a gait analysis in a clinic setting allows the analyst to dig deeper and greater ability to gather data.

The body is a series of complicated systems that all interact. This is why basic gait analysis is insufficient.

However, thanks to many advancements in technology, with so many data points and parameters, you can find answers to many questions. Remote gait analysis now has scientific and medical legitimacy.

Hopefully will grow in future and make such services more accessible to more people.

Intro and outro music by Dallin Puzey, GOIN 4 A WALK

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