How you can quantify stress.

I’m going to start with the take-home message first, then go into the explanation.

The take-home message from this article is this:  You are given a limited budget of ‘training stress.’ Think of it as a bank account. Every training session you perform has a ‘cost’ (training stress). These sessions withdraw a bit from your account. You can spend some of this on short, hard workouts or long slow workouts, but each workout takes a bit of the budget. You can re-invest in your budget by RESTING. So, you must plan your budget so you don’t run out of ‘stress.’  It is the continual juggling of stress/recovery/repeat that leads to long-term gains.

But how do you know how much a given workouts takes out of your budget??  And how do you know when you need to re-invest???

In this article I want to discuss how to quantify workout stress. In other words, how ‘hard’ a workout is. I also want to discuss how you can avoid over-doing it (draining your account).

You don’t have to have fancy software to figure this out (but Training Peaks has some really cool algorithms that calculate this). You simply need to understand the basic principles and BE AWARE of what you are doing and how you feel.

Fitness is the result of stress and recovery. Over and over, we stress our body, recover, rebuild, and get stronger. When done properly, this results in increased fitness.  When done incorrectly, this can lead to over-training, injury, burnout, and diminished fitness.

On the old ECo website, I had this picture:


The blue dots and  line represents “stress” and the red line represents fitness. You can see that with appropriate STRESS and RECOVERY, we see fitness gains!

So what do I mean by ‘stress?’  Stress is the product of three key variables: DURATION, INTENSITY, and FREQUENCY.

I want to explain what these three terms mean and provide you with the tools to figure out how to quantify your stress.

First off, we need to understand the difference between ACUTE STRESS and CHRONIC STRESS.  Acute stress occurs after a single workout. The effects last 12 to 24 hours. Chronic stress occurs with repeated efforts and adds up over weeks, months, and years.

So, we can quantify stress ACUTELY and CHRONICALLY. Both are important when designing a training program.

1) ACUTE STRESS: Quantify the training stress of a single workout.


The overall stress of any given workout can be ‘quantified’ by factoring in the DURATION of the workout (how long did you exercise?) and the INTENSITY of the exercise (how hard did you exercise?). Training Peaks has a metric called the Training Stress Score (TSS). This is a composite number that takes into account the duration and intensity of a workout to arrive at a single estimate of the overall training load and physiological stress created by that session. Simply put, the higher the number, the more stressful the workout was.

The simplest example is this: If you train for 1 hour at threshold, your TSS is 100. (DURATION = 1 hour, INTENSITY = 100%… 1 x 100 = 100). Anything less than 100 shows that you workout had ‘less stress’ than exercising for 1 hour at your threshold. Before you jump on me for this explanation, realize that this is drastically simplifying this. The actual algorithm is more complicated. I just want you to get the big picture.

When we train for endurance, there are times we want to get high TSS values. But, we need to balance these high TSS values with recovery days (low TSS values).

There are a couple of ways to get a high TSS number.

  • Go long and easy. For example if you exercise for 3 hours at a low intensity, the DURATION variable is high, the INTENSITY variable is low and the product (D x I) is relatively high (well over a TSS of 100 even though you didn’t train over threshold).
  • Go short and hard. For example, if you exercise for 30 minutes, but do a high intensity workout, the DURATION variable is low, but he INTENSITY variable is high, and the product (D x I) is relatively high (over a TSS of 100 even though you didn’t train for over 1 hour)

So, going back to the bank analogy, you can withdraw the same amount of ‘stress’ in a 30 minute workout as you do in a 2-hour workout.

The problem is when people go LONG and HARD. This is a recipe for disaster. And this is why I’ve been bugging you on social media about NOT RUNNING YOUR LONG RUNS TOO FAST!!! You are adding more stress than necessary to get the desired outcome. On the flip side, you don’t want to do too much high intensity work. Six reps of Wingate are enough right now. More reps… you’ll probably will get you diminishing returns.

2) CHRONIC STRESS: Quantify the training stress of a block of time.


OK, so now you understand that each workout you do can be ‘quantified’ based on DURATION and INTENSITY. How do you account for weekly stress? Or monthly stress? How do you know if you are doing enough or too much over the course of the week or month?

This is where the third variable, FREQUENCY, comes in.

Frequency relates to the number of times you stress your body, or more simply, the number of times you train in a week or month or year. As you can imagine, you need to balance your TSS daily stress (TSS) throughout a week, a month, and even a year so you can stay healthy and continue to improve.

Returning to the bank analogy, too many withdrawals will eventually drain the account. Some people can drain the account with one poor decision (run an extra mile, run a bit faster than necessary, train hard 3 days in a row)… Once the account is drained, it is VERY HARD to re-invest. This is called overtraining.

Our job as coaches is to manage stress. We apply stress when you are ready, back off when you need to. The goal is to keep you healthy and increasing fitness.

TEAM ECo programming contains three types of workouts:

  • Recovery workouts have a low TSS
    • These includeshort runs, rides, swims (20-60 mins at your EASY level)
  • Endurance workouts have a higher TSS
    • These include long runs or rides, medium-long trainer workouts w/ intervals.
  • Higher intensity workouts have a higher TSS
    • These include track workouts, Wingates, and threshold sets.

In the general TEAM ECo training week, I try to schedule 4-5 days where the TSS is high, BUT the TSS is high in different disciplines:

  • Tuesday Track (short workout, high intensity)
  • Wingate Wednesday (short workout, high intensity)
  • Friday swim (medium-long workout, medium-high intensity)
  • long run (long workout, low intensity)
  • Weekend bike (either long workout, low intensity or medium-long workout with moderately high intensity)

All other sessions… the TSS is low.

LAST IMPORTANT POINT: Continual stress is beneficial until it isn’t.
The key is backing off from the stress before you HAVE to. This is why, in general, we back off every 4 weeks and, instead of a ‘normal’ week, we plug in 5 days of low TSS. This allows the body to adapt, repair, and get fitter!

OK, I hope you understand how to quantify a workout and how to quantify how much you are stressing your body over weeks/months. I also hope you understand why RECOVERY is critical to staying healthy. You can’t keep withdrawing ‘stress’ from your account without reinvesting with recovery.