As you are viewing your daily workouts in Training Peaks, you may notice three numbers colored pink for “Fatigue,” blue for “Fitness,” and yellow for “Form.” These are related to Training Stress Score (TSS). TSS is calculated each day based on the duration and intensity of each activity you perform. For example, a one hour workout at anaerobic threshold would score a perfect 100. Most workouts will be at a lower intensity than anaerobic threshold, which is essentially the hardest effort you can maintain for about an hour. So most people would need to work up to multiple hours a day of exercise to achieve a TSS of 100. Let’s dive into how Fatigue, Fitness and Form relate to TSS and what this means downstream for training.
by Kristina Pattison, DPT, OCS, CSCS
DEFINING TRAINING LOAD
Acute training load, or “Fatigue,” is the weighted average of your daily TSS for the last week. For example, if you got a TSS of 100 for every day the last week, you’d average an ATL of 100.
Chronic training load, or “Fitness,” is the exponentially weighted average of training performed over the past 7 weeks. If you’re consistently averaging an acute training load of 100 per week, your chronic training load over 7 weeks will be close to 100.
Training Stress Balance, or “Form,” is the comparison of your acute training load over the last week, and your chronic training load over the past seven weeks. If you have an ATL that is greater than your CTL, your training stress balance, or Form, will be negative. For example, if you have an ATL average of 120 for the past week, and your CTL for the past seven weeks is 100, then you just performed more training than you are used to and your Form (TSB) may be something like -10. (Note: Form will be calculated from the previous day’s ATL and CTL so it may not equal today’s CTL minus ATL).
For all of us building up toward events, a TSB of about -10 to -20 is a good place to be during your build and peak training weeks. During these weeks, you will be building on your average (or base) volume, to adapt to more volume, or you will be increasing the intensity of your training, or both. During a base week, you are returning to your average volume, so you’ll likely see a TSB closer to zero.
If you are consistently training, you will likely only see a positive TSB if you are tapering for an event. During this time, you may see a peak TSB of about 10-20 which indicates you’ve rested adequately and are ready to race. If you are consistently seeing positive numbers for TSB and you are not tapering for a race, it is because you are missing enough workouts that you are in a state of gradual detraining.
CONSISTENT VOLUME
For this reason, it is important to understand your base volume and how critical it is to keep your base volume up over the course of the year. For our purposes, I use “base” volume to describe your average volume that you are maintaining over time. I use your most recent months of training to determine your base volume of running, which can be viewed in your “Stats” spreadsheet. As we go forward you will also see a note at the beginning of the week that details the goals for the current week in terms of volume and intensity. If you are steadily chipping away at Build and Peak weeks, you should see your “Base” volume increase, which is critical to hitting the mileages we need for those longer events.
As a physical therapist, I can confirm that the number one reason for overuse injuries is that novice athletes let their base volume erode (often during the winter) and then they try to hit peak volume for a race or event that the body is no longer conditioned to perform. The misconception is that “overuse” injuries come from training too much all the time. But athletes who stay consistent with their volume over time are rarely sidelined by injury. So far, with Flight Phase athletes, I have seen steady reports from athletes experiencing reduced injuries since joining the flock.
TIPS FOR ACCURACY
Tip: Make sure you record ALL your activities for the most accurate assessment of training stress score. This includes: hiking, hunting, snowmobiling, walking the dog, yoga, dynamic mobility, skiing, paragliding, etc. All activities contribute to some physiological stress on your system. Hidden stressors often will lead to sickness and injury.
Tip: On the phone app, toggle to “Charts” and ensure you have a “Fitness Report” in your Performance Management Charts. When you click on “Fitness Report” you will be able to select “sport types”. Ensure you are viewing “All Workout Types”.