Strain vs. Stress: A Small but Significant Distinction

With my successful 2019 race season now behind me, I have been thinking a lot about how much I want to refocus my time on coaching and writing. I am excited to have some new found time to reconnect with my computer and share, what I think, is some very important information with the triathlon community. I have been brainstorming quite a few topics that I will address in the coming weeks and months, but before I can write any of them, I feel that I need to address one very important topic. Strain and Stress. This concept was first brought to my attention by Tim Cusick, the WKO product leader and master coach of Velocious Endurance Coaching. What are they? Why are they important? How can we utilize them most effectively? With the explosion of more affordable training devices such as heart rate monitors and power meters, athletes are becoming much more familiar with a concept known as “training stress”. More specifically, athletes are using training stress scores (TSS) to help guide them in their training with incredible success. For me, this is an absolute staple in my training and coaching. Before diving into this form of training, however, I feel that some issues need clarification to maximize your success.

An example of using Training Stress Score (TSS) to assess an athletes overall fitness, fatigue and race readiness will allow you to better monitor your athletes ability to manage strain and adapt to stress as they become more fit and strong. In this example from 2018, the athlete had two A-races, one in the spring and one in the fall, and a few B-races which resulted in a double peak season followed by a full and complete offseason.

Strain vs Stress

In the simplest terms. “Strain” is what you put in and “stress” is what comes out.

Stress is a state of mental, emotional, [or physical] “strain” or tension resulting from adverse or very demanding circumstances. In this definition, we can see that stress is the result occurring from “strain” placed on the mental, emotional or physical state. If we were to think of this in a real-world scenario that most of us can relate to, think back to the days of high school. I’m already feeling the stress just thinking back. The “strain” would be the fact that there is a 10-page paper on the symbolism found in “of mice and men” due tomorrow morning. The stress generated from that strain may show up as anxiety, depression, procrastination, elevated heart rate or even high blood pressure. The “strain” is what is causing “stress”. This is a very small but very important distinction. Let’s now put this in the context of our training. If I were to prescribe you a workout with your typical warmup, 3 x (25 mins Sweet Spot (SST) with 3 min Steady State Recovery), followed by a cool down with a duration of your choice, we can start to tweeze out important distinctions. The 3 x 25 mins of SST work is the “strain” that I am placing on your physiology, this strain results in stress, that stress stimulates adaptation. But how?

General Adaptation Syndrome (GAS)

It may be pretty well ingrained in our minds that stress is quite a bad thing. That’s generally true; unmanaged and overwhelming stress can wreak havoc on your emotional and physical state. The key words there are “unmanaged and overwhelming”. The truth is, we are incredibly good at adapting to appropriate levels of stress provided it is in the proper context. This is the general principle behind learning a new skill. Very rarely are we talented at something when we first try it. However, after a lot of repetition and increasing complexity, we tend to become better and better. This is true in terms of your physiology as well.

The GAS principle tries to put this in simpler terms. The principle proposes that there is a three-stage process that describes the physiological changes your body undergoes in the presence of stress.

Alarm Reaction Stage

The alarm reaction stage refers to the initial symptoms the body feels in reaction to stress. One of the most common physiological responses that you may be familiar with is the “fight-or-flight” response. Your heart rate increases, pupils dilate, adrenal glands release cortisol, and you get a nice shot of adrenaline. This is an alarm or reaction and can be of varying degrees of intensity based on the stimulus of strain and resulting stress.

The General Adaptation Syndrome (GAS) principle. There are three stages in this principle: 1) Alarm - Rapid response to stress 2) Resistance - adaptation to a sustained stress 3) Exhaustion - a return to homeostasis followed by exhaustion to the stress and an inability to adapt to said stress or any additional stress added to the system.

Resistance Stage

After the initial shock of the stressful event, the body will attempt to return to prestress conditions. An equilibrium, known as homeostasis.  Cortisol levels drop, heart rate slows, blood pressure decreases, and your pupils return to normal. However, your body is still in a state of “high alert”. If you are continually exposed to stress, your body will begin to adapt and learn to live with that new heightened level of stress. You may not even realize that your body is still coping with this elevated level of stress. People often describe themselves as irritable, frustrated and unable to concentrate at the high end of this stage.  If the stress is not managed, you will enter the third stage of the GAS principle.

Exhaustion Stage

This is the stage of prolonged excessive chronic stress and is what we want to avoid at all costs. Being exposed to chronic stress can lead to physical, mental and emotional exhaustion to the point that your body is no longer able to adapt to the stress. Unmanaged and overwhelming. People in this phase typically use the terms fatigued, burnt out, depressed, and anxious to describe their emotional state. This state will also weaken your immune system putting you at an increased risk of illness.

Stress, is Stress, is Stress

Stress can come in many different forms. It is important as an athlete and as a coach to be able to recognize all forms of stress and be able to understand their impacts on adaptation and future “strain” that you want to put in the athletes system in order to maximize physiological adaptation.

It is important to note in this phase of the article, that stress, is stress, is stress. What I mean by that is that stress is a cumulative creature. Your body can adapt to a finite amount of stress at any given time and this stress can come from anywhere in your life. We often refer to “training stress” in our workouts, however, physiologically, this elicits the same response as that stressful 10-page English paper. When managing stress, we have to look at the big picture. “See the forest for the trees”. Too often we look at the “tree” or the workout stress and we ignore the “forest” or life stress. This is why every one of my athletes is treated differently and the line of communication between us is VITAL. Some of my athletes are balancing high-level career demands (CEO’s), family responsibilities (multiple children), social responsibilities (non-profit fundraisers) and more. Some athletes are lucky enough to be able to limit these external stressors allowing them to increase their “internal” or training stressors. If athletes are actively trying to manage stress through things like sleep, nutrition, even meditation, then their ability to cope with stress is extended and our training schedule will reflect that. The more that you can manage your external stress, the more success you will have in adapting to your training stress. Period.

Prescriptive vs. Descriptive

In principle, it is better to prescribe “strain” for a workout and use things like heart rate to “describe” the stress encountered in the workout. This will allow you to best quantify load, fatigue, and adaptation in the workout and training block of an athlete.

This brings me to my final and maybe the most important point of the article. I often talk to my athletes about “training toys”. I have had athletes who are very successful without any gadgets, don’t get me wrong. No watches, no heart rate monitors, no power meters, just good old-fashioned rate of perceived exertion (RPE). However, it is important to look at these pieces of equipment on a spectrum. RPE is the far left, good for training and you can have a lot of success, but if you use a heart rate monitor, you are likely to be more efficient in your adaptation to training. If you choose to use power, you are likely going to be even more efficient at adapting to training stress compared to just a heart rate monitor or RPE alone… As you move from left to right on this spectrum, I don’t want you to neglect what you have superseded. If you use power, I still want you to pay attention to RPE for given effort levels. I still want you to monitor heart rate while using power, especially come race day. Here is why. Heart Rate is a measure of “stress” whereas Power is a measure of “strain”. If we go back to the workout I described earlier… 3 x 25 mins of SST work. If I prescribe 3 x 25 mins at 240W +/-10W, I am prescribing the “strain” I want to put on your physiological system. If your heart rate averages 150bpm for those 3 x 25 mins of SST, that is a measure of stress that your body has been put under. A great way to tease this out is by looking at the same prescribed workout on two different days. On day 1, you have slept well, you are on vacation and your avg HR is 150bpm. On day 2, you didn’t sleep well, your family is in town visiting and you are trying to fit a workout in between social events and your avg HR is 164bpm for the intervals. The “prescription” of power was the same in both workouts but the “stress” can be described as harder on the second day of the workout due to the “forest of stress” we mentioned earlier. Heart rate zones were never really designed to be prescriptive, i.e. go out and run at 145-150bpm. They were designed to be descriptive, as in post-workout analysis. i.e. “Oh, I spent 15 mins with a heart rate between 145-150bpm around high tempo”. With that being said, we can use them to prescribe workouts, they may just be more variable than we would like. A much better way is to prescribe the “strain” we want on the physiological systems and see how the body responds to the stress using “HR” after the fact, as a descriptive result. We then use that descriptive result to adjust the “strain” we want to put on the athlete in future workouts. This, to me, is the biggest benefit to power training and why data, when taken together, will give you a much more holistic “forest” view of your athlete and their adaptation. I cringe every time I hear an athlete or coach say they no longer pay attention to HR because they use power.

I will end with, all of that being said, with there is nothing better than unplugging and going for a run, ride, or swim with no goal or metrics in mind. Don’t forget that we are all here because we love all three disciplines and the sport itself. Sometimes you need to unplug and fall back in love with why we do this.

May your stroke be smooth, your wheels roll free, and your feet carry you to unknown lands.

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Talk soon,

Coach Tom