• Josh Fields

Data: The Good, the Bad and the Ugly

Updated: Feb 22



In a previous post, I talked about the reasons why the “fitness” metrics on today’s GPS watches should be ignored. In this post, we’ll take a look at some of the other pieces of data available to the modern runner, and whether I think you should care about them. Hang on, we’re taking a deep dive!


The Good

Today’s technologically-minded runner has a vast amount of data available to them both during their runs and for later analysis. These include distance, pace, heart rate, elevation, cadence, ground contact time and L/R balance, braking, hip drop, torso rotation, blood oxygen level, power… an upcoming product even promises that lactate and glucose levels can be sensed and recorded. Add to these basic metrics a plethora of data that all rely on these numbers, such as the “fitness” scores we discussed last week.


The Bad

Too much data can have runners focusing on things that really don’t matter–or worse–aren’t accurate.


The Ugly

This excess data can cause runners and even coaches to make incorrect decisions about modifying training. In some cases a runner can get depressed or demotivated about their current fitness level when they’re in the heat of training, based on numbers that don’t paint an accurate picture of their true fitness.


So, what to do? What data SHOULD you pay attention to? As I alluded to last week, my simple answer is to focus on as little as possible.


Tracking Volume

At a minimum, runners should have some way of tracking the overall volume of their running. Whether by mileage, time or both, you should be able to track how your volume increases or decreases throughout the year. Combine that with a solid sense of your perceived effort, and you have everything you need for a successful training cycle. You don’t NEED anything more. I work with several athletes who do all their training with nothing more than a timex, and sometimes they even leave that at home. Unless you are at the absolute pinnacle of your potential in sport, absolute precision is not only not necessary, but can be counterproductive.


Heart Rate

Stepping up the data ladder, if you like more numbers, have trouble running a steady effort, or are returning after an off-season, it can be helpful to track heart rate. (Perceived exertion can change after an off-season, injury or other period of extended rest). The caveat is that most optical (wrist) HR systems are not consistently reliable for many people. I highly recommend a heart rate strap if you choose to track heart rate, and in fact would recommend defaulting to NOT trusting any wrist-based HR.


Pace

Here’s where we get into the “it’s different for everyone” area. Tracking average pace for your runs can be helpful for some people so they can see progress. However, you know your brain best. If you have trouble detaching from the numbers, and tend to overanalyze the paces, you should ignore it, or set your watch so it doesn’t display live pace. An example: You’re out on an easy run, which for you is usually 8:30/mi. You’re feeling okay, but you look down and the pace says 9:15/mi. What do you do? If you ignore it and keep chugging along at whatever effort feels easy, pace is probably okay for you to be able to look at it. If you either pick up the pace to your normal 8:30/mi, or start beating yourself up and questioning why you’re running so slowly today… you should at least take the pace off the watch display!


Ground contact time, L/R balance, cadence, etc

These metrics, if accurate, can occasionally be helpful in analyzing whether you’re compensating for an injury, or have a non-bilateral weakness. It’s certainly not necessary for most people, but can occasionally come in handy especially if you have a mild injury that flares up now and then. If you notice that the L/R balance is far off your baseline, you may be too fatigued to have a balanced form. Long-term, that injury or weakness should get corrected!


The Nonsense Power, torso rotation, hip drop, lactate levels, glucose levels, blood oxygen levels. These vary from the inaccurate to the unhelpful. For the vast majority of athletes in the vast majority of circumstances, these numbers don’t matter a bit.


The Bottom Line

There’s something to be said for having accurate data to aid your training decisions. Being able to see themselves getting faster helps many runners stay motivated to get through a training cycle. Many other runners tend to overanalyze the numbers and get into comparison mode. Theres no single right answer to this; you need to know who you are and how you respond in these areas. Unless you know that you’re not the type to overanalyze data, I would start by tracking only volume, and add in just what you think you need.


Avoid the temptation to look at data for it’s own sake. If you have a need of it to guide your training, use it. If you don’t, ignore it!