Run Power: Do We Really Need More Numbers to Analyse?

by Cat Hine

Within the world of triathlon, we love to talk numbers.  Cycling conversations have become synonymous with FTP (Functional Threshold Power) and watts per kilogram. This is a great way to measure effort regardless of other variables.  Even if we don’t have power metres on all of our bikes, apps such as Strava will give us a rudimentary estimated power number, so that can be considered aside from our rating of perceived exertion.

However, when it comes to running it’s more difficult to gauge how hard we have been working.  Treadmills are much larger than turbo trainers, and as such, most of us don’t have the space to accommodate one. Thus we do our running outdoors and therefore can’t control external variables in order to complete our training. As such we are left with traditional run metrics; pace, heart rate (HR) and RPE (or feel).

Running based on ‘feel’ is the least scientific of the measures.  One day we may feel great and another day we may feel crap, while putting out the same effort.  It is important to be aware of RPE and how our body is responding to sessions, but it is the least objective piece of data we tend to use.

Pace is a notoriously blunt metric: intervals don’t take into consideration hills or headwinds. This impacts the quality of our sessions and/or ability to track progress. We may be working a lot harder than intended, or our pace drops off. Working entirely on pace can therefore overstretch us. When racing we want to have something left in the tank for the end of the course, because ‘blowing up’ in the final few kilometres is never a good idea!

Heart rate zones as a measure of intensity are also somewhat unreliable.  Having a big cup of coffee or being stressed (or ill) will impact our HR.  When completing track intervals or hill repeats it’s easy to see that HR lags behind our efforts. We may be working at the wrong intensity before our all-telling smart watch sends us a notification that we’re in the wrong zone.  There are also a host of arguments around how we derive HR zones; 220-age? Percentage of max HR? Tested lactate threshold?

So is there a metric that is more stable and reliable? Enter run power.

David Starr of Eat Drink Win recently lent me a Stryd Power Meter to demonstrate the benefits of training with more objective data.

Living in a notoriously hilly part of the UK, I have always found it challenging to manage pace and effort.  The Stryd power meter takes into consideration hills, wind, form and fatigue, so you can train at the ‘right’ intensity regardless of where you are.  Real-time power data is displayed on your watch and you can set alerts to ensure that consistent power is maintained, or that you get to a desired intensity quickly when completing intervals.  This helps to manage training loads and minimise the risk of overtraining.

When it comes to race day, that power data can be used to manage effort and ensure that, like with the bike, you don’t overcook the initial sections when you’re still feeling fresh.  On a more long-term basis, power can be used in conjunction with HR and pace to identify efficiency gains at certain power outputs.

In addition to power data the Stryd can also provide a host of information about run form efficiency.  Cadence, ground contact time, vertical oscillation and leg spring stiffness can all be measured through the foot pod.  With this data, your coach will be able to set specific drills to help improve run dynamics, helping you to use less energy while moving at optimum speeds.  Pace and distance calculations also appear to be more accurate than some GPS devices.

Running with power is still a relatively niche area, despite the tech being a few years old now.  However, with more and more of us engaging with the vast array of data available through indoor training, it seems that we are more open to using hard numbers versus traditional methods of monitoring effort and performance.

Run power is certainly one way of using technology to help improve training.  And who doesn’t want to have another set of numbers to analyse while sipping a protein shake after track?

Cat Hine is an MX Endurance Race Team ambassador.

(Header photo by Cameron Venti on Unsplash)

Want to find out what MX Endurance is all about? Use the code MX2FREE to enjoy your first 2 months for free!