Your running watch explained: How to understand the stats

We demystify the jargon to help you get more from your running watch

If you're using your GPS running watch just to track your distance and pace, you're missing out on a huge opportunity to improve your running.

Sports watches are packed with sensors and stats that can turn you into a better, faster and less injury-prone runner – it's just a case of understanding the data and using it to your benefit. But knowing how to interpret all that data can be tricky.

Read this: Cycling metrics explained

If you've picked up a new Garmin watch like the Forerunner 935 or Fenix 5, or invested in the insanely detailed Polar V800 or the wallet-friendly Polar M430, you'll probably have noticed that there's a whole flood of new running metrics to wade through.

Here are ten clever smartwatch stats and what they mean for your PB.

1. Cadence

Your running watch explained: How to understand the stats

Cadence or foot strike rate is the number of steps per minute (SPM) you take. It's a vital stat for assessing the efficiency of your running form and thankfully is something that's relatively easy to improve once you're aware of it.

Just like vertical oscillation, some running watches will use sensors in a heart rate chest strap to fire a SPM figure to your wrist, while older generations tend to pair up with a shoe pod.

A typical cadence is between 150 - 200 steps per minute but experts put 180 SPM as the sweet spot for optimum running efficiency for reasons best left to the physicists to explain.

A great way to work on your cadence is to find a 180BPM soundtrack for a shorter run and use the beats to quicken your strike rate. If you're struggling to find suitable music, we've found Spotify Running pretty useful.

For newer Garmin watches, you'll also notice a Metronome feature that will play tones at a steady rhythm to help improve your cadence. To set it up, head into Activity Settings inside the Garmin Connect app and you'll be able to customise beats per minute, alert frequencies and metronome sounds.

Best running wearable to buy: Moov Now is worn on the foot to track cadence effectively. Alternatively, you can also try out the Lumo Run sensor or a footpod sensor to get accurate cadence data.

2. Vertical oscillation

Watch any professional runner in action and you'll notice that there's very little movement in their upper body. Their top half glides swan-like while their legs do all the work under the surface. One measure of this optimum running efficiency is called vertical oscillation and shows the degree of 'bounce' in your running motion.This bounce is measured in centimetres from a fixed point on your body (in the case of GPS running watches this tends to be a sensor built into the heart rate chest-strap.

Typical oscillation is between 6 and 13 cm with the Paula Radcliffe's of this world moving at the lower end of that scale. So why is it useful to be able to monitor vertical oscillation? Well, it's all to do with running efficiency and not wasting energy as you put in the miles. Ideally, you'll want to reduce that 'bounce' and that's closely linked to increasing cadence, which we'll talk about next.

Best running watch to buy: Pair the Garmin Forerunner 935 with Garmin's Running Dynamics Pod to get real-time vertical oscillation stats.

3. HR Max

Your running watch explained: How to understand the stats

Maximum heat rate (HR Max) is the highest number of times your ticker will beat in a minute when you're going all out at your most intense work out level. Your HR Max is unique and depends on your genes and how old you are. The longer in the tooth, the lower your HR Max.

Why is it important? Your maximum heart rate dictates the ranges for all the other zones in heart rate training. The more accurately you know your HR Max, the more accurate your sport zones, and accurate sport zones equal more effective workouts.

There are a number of methods for calculating your HR Max. The most accurate is in a lab, another is using the formula 220 – AGE. In most cases you can manually add your stats into your running watch or they'll also estimate your HR Max based on a fitness test or even a recent workout

So can your improve your heart rate max? In a word, no. Training has little or no impact. What you can work on is reducing resting heart rate. Fortunately for you, we have an entire guide dedicated to using wearables to lower your resting heart rate, which also explains why it's important part of your running routine.

Best running watch to buy: The TomTom Spark 3 or the Suunto Spartan Trainer Wrist HR offers some of the most accurate heart rate data from the wrist.

4. Basal Metabolic Rate (BMR)

Like a lot of stats your running watch offers up, the best way to find your Basal Metabolic Rate, or the number of calories your burn by just being alive, is to get in a lab with a gas exchange masked strapped to your face. But in lieu of these expensive tests, we're now seeing some watches offer up estimates based on the vital info you supply at set up, such as age, weight and height.

Knowing how much energy your body burns in a given day when you're at rest is really useful if you're looking to get lean or just working out how much you need to eat to stay well fuelled for your training regime.

Best running watch to buy: The Polar V800 breaks down your daily calorie burn into how much your burn with BMR, Activity and Training.

5. Heart Rate Zones

Using your HR Max, different running watches break down your heart rate zones or 'sport zones' into segments and make them easy to understand with different names or colour coding.

Read this: Understanding heart rate zones

Different devices give them different labels but they break down like this: Recovery training (60% of MHR), endurance base training (65-70% of MHR), aerobic capacity training (75-82% MHR), anaerobic threshold training (82-89% MHR) and maximum aerobic training (89-94% of MHR).

It's worth noting that everyone burns fat, rather than carbs, as a main fuel source at different heart rate levels but having your heart rate zones estimated gives you a far better shot at getting the workout effect you really want to achieve.

Best running watch to buy: Garmin Forerunner 935, TomTom Spark 3, Polar V800.

6. VO2 Max

Your running watch explained: How to understand the stats

VO2 max sounds like some kind of complicated chemical compound from a school chemistry lesson but the precise definition is the maximum volume of oxygen (in millilitres) you can consume per minute per kilogram of body weight at max performance.

Read this: A comprehensive guide to VO2 Max

In layman's terms, it's related to your body's ability to consume oxygen. This is important because the higher your VO2 max is, the better the body can deliver oxygen to your muscles helping you to run longer and harder. When you get fitter, your VO2 max should increase.

It's one of the most important running metrics because it can also have an impact on running efficiency and improve form to help prevent injuries.

Just like HR Max, the most accurate way to find out your VO2 max is under lab conditions using expensive gas exchange equipment but many of the best running watches now use intelligent algorithms and a heart rate monitor to estimate your VO2 max based on your vital stats and recent workout performance.

If your running watch supports VO2 max readings, you can get an estimate of your current level by pairing with a heart rate monitor and running outside for at least 10 minutes.

Unlike your HR Max, you can train to improve your VO2 max.

Best running watch to buy: Garmin Forerunner 935 andPolar V800

7. Orthostatic Test

An orthostatic test measures your heart rate for a period while at rest, before doing the same for a period while you're standing up. From this you get peak heart rate, standing heart rate and resting hear results which can be used to benchmark your overall condition and how ready to you are to get back out and train.

If your resting heart rate is 10 or more BPM above your average – a sign of overtraining - then you can consider resting.

Best running watch to buy: Polar V800

8. Ground contact

Another smart stat you can use to improve your form if you've got a high end Garmin up your sleeve, Ground Contact time is the amount of time during your running that your foot is on the ground rather then flying through the air.

Read this: Running power meters explained

Measured in milliseconds, a typical runner will have a ground contact time that falls somewhere in the 160 — 300 milliseconds range. Talented types like Mo Farah and the Geoffrey Mutai spend about 190-milliseconds in contact with the ground each step.

Garmin found that there is a connection between injuries and greater imbalances with some runners. Ideally, you should have a pretty symmetrical running form. It's something closely linked to cadence as well, so as cadence increases, your ground contact time decreases and you should be running quicker. Reducing the ground contact time can also reduce the risk of injury.

So how do you reduce ground contact? There's a few things you can work at like shortening stride length. This is the length of your stride from one footfall to the next. You can also focus on strengthening glutes and adding some sprint training to your routine.

Best running wearable to buy: Moov Now, MilestonePod, Stryd footpod, Lumo Run

9. Lactate threshold

What is your body truly capable of? Measuring lactate threshold is one way of giving us a clearer insight without going through the more complicated process or drawing blood while you're sat on a treadmill inside a sports lab.

It's all about running intensity and endurance here and the process when lactic acid is being dramatically produced in the bloodstream. When you exceed that threshold of lactic acid build up, that's when fatigue starts to kick in and you're level of effort or pace is affected.

According to Garmin, the threshold for experienced runners should be 90% of their maximum heart rate. For average runners, it's below 90%. This data is important because it can indicate how much you have left in the tank, whether that's in a race or during an intensive training session.

It's one of the most valuable metrics for runners and while the best methods of testing it are reserved for the lab. If you don't have a running watch that supports measuring it, you can do it with an external heart rate monitor and running watch on a treadmill or on a flat road road where you can keep a consistent pace.

Simply warm up for around 10 minutes, then run for 10 minutes. Hit the lap split button and once you've hit the 30 minute mark, hit stop. You'll now have average heart rate readings for the first 10 minutes, the last 20 minutes and the full 30 minutes of the run. You can then use the 20 minute reading as an estimate of lactate threshold.

Best running watch to buy: Garmin Forerunner 735XT, Garmin Forerunner 630 and Garmin Forerunner 935

10. Excess post-exercice oxygen consumption (EPOC)

Your running watch explained: How to understand the stats

Now we're getting deep into the science. Excess Post-exercise Oxygen Consumption, or EPOC, is the measure of the boost in metabolism (calories and fat burning) your body gets after a workout. Sometimes also know as afterburn.

We all know that when we pound the pavements or bench our own bodyweight, we burn calories to fuel our muscles, but when we're done, we keep on burning, firing and flaying more fat than we would normally at rest. It's all down to what our bodies need to recover from the hard work they've just done.

Some Suunto running watches offer predicted EPOC as a great way to measure the training load of high intensity exercise. Keeping an eye on this number in real time helps quantify the exertion of a training session, giving you the option to stop once you hit an EPOC number.

Tracking EPOC over time also lets you build a good picture of which sessions you personally find more demanding and plan your recovery of training accordingly.

Best running watch to buy: Suunto Spartan Trainer Wrist HR


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