Training Metrics: When to Use Them... and When Not to

By Coach Chad Carpenter

There is a time and place for everything, and this concept certainly applies to training metrics. With all the wearables, online platforms, and data analysis methods built around endurance training, feeling “paralysis by analysis” is quite common. A few years ago, heart rate monitors were only used by the curious elite, but now, it seems like every person not only has a monitor on their wrist, they also wear monitor another across their chest. Our phones receive a notification every morning that inform us of the quality of our sleep and remind us throughout the day to get you 10,000 steps, regardless if you already had a bike, swim, or strength workout. Some platforms even have the audacity to tell us we should rest for 40+ hours after a workout even though we have not even gotten to the hard workouts later in the week. Do we have to listen to all of this? Short answer: no, but you should listen to some.  Let’s first talk about some post-event metrics (e.g. sleep or average pace) and then we will talk about in-situ metrics (e.g. heart rate or power).

FOCUS ON TRENDS AND CORRELATIONS, NOT SINGLE DATA POINTS

Picture this. You get your new fitness tracker, be it a Garmin, Fitbit, or whatever you fancy, and after the first night wearing it, the tracker gives you an indication of low sleep quality. Does this make you a poor sleeper? Probably not. It is easy to land into the pitfall of feeling like an underachiever when receiving a single data point that ‘indicated’ less than optimal results. You would be surprised how that single data point can completely affect our day and decisions from the unintended bias that notification enabled. You may have not felt tired throughout the day, but now that you checked your sleep score after lunch, you suddenly feel tired and bogged down. We can be primed into feeling this way by a metric that is subject to error and only a small piece of the entire picture.

There is more to this story. Let’s say that with the same tracker, you usually average about 7.5 hours of sleep a night. However, for a stretch of 3 nights, it determined you only achieved around 6 hours of sleep each night. A change in the data trend is worth exploring and reflecting on. Additionally, if you can also see that your resting heart rate also increased throughout that same 3-day span, it might be time to reduce the stress in your day as you could be over trained, over stressed, or simply coming down sick. Trends and correlated metrics are difficult to argue with and should be considered into how you adapt your lifestyle.

This concept of interpreting trends instead of single data points applies to performance output metrics as well such as bike power or running pace. If you go to a single, track session, but your lap splits are not as fast as they were last week, do not freak out. Fluctuations in performance can and will exist workout to workout. I would be very suspicious if they did not. However, if you are showing consistently slower splits over a few weeks, then it is time to reflect and seek feedback. Have you also noticed an imbalance in your strides such as more ground-contact-time on your left side than your right side? Has your load in your bike or strength workout also increased? You could have picked up a bad habit in your run form or maybe you are chronically fatigued or on the brink of a real injury. At the end of the day, you should not worry until you see a steady trend. If you do, then take action.

KNOW THE INTENTION OF THE WORKOUT

We not only analyze and assess metrics after our workouts, but often we can let the metrics drive how we train. When using or not using metrics during your workout, you should know the intention and focus of the workout. Are you aiming to get some hill work and build up strength endurance? Are those 100m laps for time at race pace or just an easy recovery swim? If you are feeling leg fatigue, should you still push to race power?

When building your own workouts, you should be deciding what the intention of a workout well before execution, and then build the workout plan or structure around that intention. For those who are part of a group program or have a personal coach, make sure you understand the intention of the workout before deciding if or how to use the live metrics to get the most out of your workout. For example, for the ‘long endurance’ runs, I often recommend athletes to not look at their pace. Instead, I would suggest that they give me the best running form at a pace that keeps them near a particular range of heart rate. If their heart rate goes above the prescribed range, then they get a walk break. The intention of the workout is to accumulate time in a smooth, good form and aerobic condition. This pace is a secondary outcome, not a primary input. This approach not only empowers the athlete to adjust their perceived effort based on the terrain (flat, hilly, trail) and weather (hot, cold, humid, dry) but also frees them from worrying about pace and performance. After a while, I find the athletes start to calibrate their ‘inner animal’. They know exactly the perceived effort needed to hit the target metrics, and they do so without looking down at their watch or bike computer all the time.

On the flip side, an athlete may have a workout that asks them to hit intervals of threshold power on the bike. If the athlete is consistently getting up to the prescribed power but still feels fresh as if they can go a little deeper, should they continue to stay at the initial target power? More often than not, I am going to tell them to lay down the watts and show me how much further they can go. As long as pushing a little harder does not interfere with their training or recovery in the coming days, this can be a great opportunity for the athlete to reach a new plateau or learn how their body responds to a little extra effort. It takes a smart athlete, and a smart coach, to know when to stick to their target metrics, when to push harder, and when to back off.

BRINGING IT ALL TOGETHER

When it comes down to it, metrics are just information and not hard lines to train or live by. As with any information, it is up to us to decide to use the information or ignore it and move on with our day. Be skeptical of single data points but highly reflective when you see trends and correlations form, both good trends and bad trends. Know the intention of your workouts and which metrics are important for those workouts. At Playtri, we often keep our workout structure simple with heart rate zones based on your blood lactate threshold which has proven to be effective over and over again. By keeping it simple, we keep it not only easy to follow, but repeatable for athletes to achieve success. If you wish to find out more, make sure to contact Playtri about our blood lactate testing or talk to one of our coaches about one-on-one coaching.

Coach Chad is a Playtri Level 2 Coach and IRONMAN World Championship Qualifier. Learn more about Coach Chad at www.playtri.com/chad-carpenter.