Technology - specifically wearable devices that measure time, distance, GPS, power, speed, heart rate, HRV and more - is part of everyday life if you’re a data-driven triathlete. We’re continuously gathering a wealth of information from our bodies while training and while resting. This technology even attempts to quantify recovery through a readiness score or recovery status.
Seeing as recovery drives all performance, that’s a noble goal. Understanding your state of recovery is critical to healthy, successful training and racing. When preparing for a triathlon, there’s a fine balance between training, daily life stresses and proper recovery. The question is, can technology properly assess that balance?
Where do the Numbers Come From? Algorithms
That watch on your wrist is a little computer gathering data on your body. It gathers all the information we feed it daily and then analyzes it with proprietary algorithms - i.e., we don’t know all the details.
Training watches record a multitude of variables and boil it down to a single measure of how much stress a given workout puts on our bodies or how well we’ve recovered from yesterday’s training. Think the Training Stress Score (TSS) or Readiness/Recovery Score. These are called composite metrics, a bunch of data boiled down to one number.
In order to understand what recovery status means, we also need to take a look at the measurement of training load. What is the effect of training on the body? Specifically on each individual’s body?
Think of training load as the physiological and physical cost of a workout. Over time, fitness, speed and performance all improve with proper training and recovery.
When our GPS watches and other devices measure training load they take in the time and intensity of the workout and spit out a metric. There has always been a stronger emphasis on duration rather than intensity in the training load metrics we see on our watch. Yet a long aerobic bike can be less taxing on a body than a hard interval run. Most versions of training load calculation overvalue duration and undervalue intensity.
Composite Recovery Metrics
For recovery, your watch will look at a bunch of variables: HRV (heart rate variability), RHR (resting heart rate), sleep duration and quality, training duration and intensity, etc. It combines them into a single metric that tells you how recovered you are or how ready you are to perform that day, e.g. “You need 36 hours of recovery”.
Yet, because the devices measure so many variables, e.g. physiological and behavioral scores, you may be left guessing as to why you’re getting a high score or a low score on any given day. Is it because you really trained hard? Or did you stay out too late the day before or had a restless night of sleep?
What to Believe?
In scientific terms, the challenge lies in the variability of the data we are measuring: yards, meters, power, RPE, HR, miles, pace, swimming with or without a wetsuit, paddles or buoys, etc. coupled with our other life behaviors and stressors. All of these are measuring different data points, thus muddying the scientific waters. The problem becomes: can I use all of this to predict performance or recovery?
Roughly, maybe. With true accuracy? No.
The apps and devices are taking myriad data from many sources and “guessing” what your recovery time should be. Data does not equal scientific truth.
Composite scores simply are not reliable. It’s best to use singular metrics to measure the activity they represent. For example, HRV measures parasympathetic nervous system activity, nothing more, nothing less. It doesn’t measure your fitness or your ability to perform on the day (1,2). HRV trends plus assessment of how you’re feeling that day are a good way to determine if you need to make modifications to your training.
Prediction with current metrics is a best guess by a computer.
Training load and recovery information is still valuable and worth looking at, just don’t rely on any single number to decide your training for the day.
As consumers, we must become more aware of potential issues and limitations with various features, such as training load and recovery composite metrics. Be the detective in your own life and with your own body.
Are Recovery Metrics Reliable?
Yes and no. Any individual metric gives you valuable information about both training load (power) and recovery (HRV). Plus, gathering information about how your body responds to training and life stresses is always valuable. Where it is not so robust is in the composite metrics. Trying to boil down a multitude of variables and data into one predictive score falls short of marketing claims and expectations.
The Bottom Line
Take in and use the valuable data and information. At the same time, understand that it is merely data and not the outcome of scientific research. It’s great to seek more information about your body and how it responds to varying amounts of recovery and training loads, but composite training metrics that result from your hard data points should be taken with a grain of salt when predicting both recovery and performance.
Resources and Articles
- Eriksson, Mikael. The science of training load with Louis Passfield, PhD - EP#3541. That Triathlon Show Podcast, June 8, 2022.
- Eriksson, Mikael. Heart Rate Variability - New perspectives and insights with Marco Altini, PhD - EP#325. That Triathlon Show Podcast, February 14, 2022.
- Hutchinson, Alex. Your Watch Doesn’t Know How Much Recovery You Need. Triathlete Magazine, June 15, 2022.