The Optimized Stress - Recovery Visualization

Wearable devices can help sports performance in a number of ways. They can help us understand how stressful a workout is, meaning how much physical work the athlete does and how fast they do it. They can also tell us how strainful a workout was, in other words, how much the stress applied affected the athlete’s body. 

The Problem and Solution:

Coaches and athletes can calculate athlete strain from heart rate data, and recovery from heart rate variability (HRV) and sleep data. However, the problem with heart rate is that it measures the response of the body, not the actual stress applied through training. One way of solving this is by measuring athlete stress directly with a power meter. Power-based metrics can be much more precise and accurate than heart rate, and have led to the refinement of power-based training methodologies over the past 20 years.

Today we are describing our solution of integrating power-based measures of athlete stress and strain with measures of recovery like HRV and sleep. Just as importantly, we would like to present this data in a way that makes sense to people who aren’t scientists or professional coaches.

Introducing Optimized

We’d like to introduce Optimize: a data visualization that leverages power meter and wearable data for a 24/7 representation of the athlete’s balance between stress and recovery.   Optimize uses the “Goldilocks Principle”: is the porridge too hot, too cold, or just right? In this case, just right means optimized. 

New Way of Measuring Stress: OTS

In order to express the athlete’s optimized state we needed to create a better way to measure stress from power data. Thus, we are also introducing Optimized Training Stress or OTS

The OTS is calculated from the athlete’s power data based upon both how long they rode plus how hard they rode. However, our proprietary algorithm factors in a rider’s fatigue during the ride, along with their carbohydrate intake (or lack thereof), which directly impacts how stressful a ride is.

For example, OTS in the fifth hour of a ride is calculated differently than in the first hour of ride before intra-session fatigue and carbohydrate intake begins to impact the athlete’s physiology. 

 OTS + Sleep + HRV = the Optimized Data Visualization

The Optimize algorithm uses OTS + Sleep + HRV to present the athlete’s balance between recovery and stress.  It is a visualization of the athlete’s whole day, not just their 3 hour ride or their 7.5 hours of sleep. The Optimize Algorithm presents actionable insight, which can help both athletes and coaches make better decisions about how training and recovery should be managed on a day to day basis.

Power Output on the Y Axis

In the image above, power output is expressed on the y axis. When the athlete is fully optimized he or she should be able to achieve the target power output for a training session and fully execute planned training. When the needle is pointing towards the right, training readiness is decreased which may result in suboptimal sessions. This suggests easier workouts and rest days might be in order. When the needle is further to the left, it suggests the athlete may need to increase their training load to better build towards their potential.

What Optimize Answers

In short, Optimize works to aggregate athlete data, analyze it using a variety of mathematical and AI techniques, and then help the athlete and coach answer three key questions.

  1. How prepared is the athlete to train today?
  2. How much training can the athlete handle today?
  3. Should the athlete train harder or easier today or continue to follow the plan?

Future applications include:

#1 using Optimize’s AI/ML to determine optimal training loads for peak performance in the Tour de France, IronMan, Boston Marathon and any endurance endeavor. 

#2 using the answers from questions #'s 1- 3 above to dynamically change workouts downstream in the training plan based on how the athlete is or isn't recovering and adapting to the training.


Dr. Phil Skiba is an algorithmic performance engineer, elite endurance coach and Sports Medicine doctor.  Phil recently worked on Nike’s Breaking 2 project to help Eliud Kipchoge run a sub-2 hour marathon.

Frank Overton is the founder and CEO of FasCat Coaching with 20 years experience coaching and analyzing data from pro’s to enthusiasts of all abilities all over the world. 

Copyright © 2022 FasCat Coaching - all rights reserved. 

Optimize is in development and will be available as an in app monthly subscription this Summer.  Subscribe to our email newsletter 👇 to be notified of its release!  In the next post, we will describe how OTS is calculated and what it measures.