Too much stress, not enough recovery and our body is primed for a state of injury, illness, or worse, burnout. It’s a simple, but largely true, way to look at the world of training. We know there’s this sweet spot where we can push our athletes hard enough to where they adapt to the training, but not so hard that they get overtrained, injured, or sick.

It sounds simple enough and it’s probably true. We are mostly concerned with pushing too hard. Whether it’s too many miles, too much repeats, or too little rest to allow for this, the danger arises in pushing.

An increase in stressors, naturally should lead to an increase in susceptibility of our body to handle said stressors. It makes intuitive sense then that if we decrease the stressors, our body should be more robust and primed to adapt. We’re never worried about doing too little increasing our stress load.

Immune Suppression

Researchers took Elite female soccer players and tracked their training load and stress markers.  Training load was measured using session-RPE, while stress symptoms were measured using a mix of questionairess and physical data. They used the Daily Analysis of Life Demands and Upper Respiratory Symptom survey to measure both daily stress and whether or not people had symptoms of upper respiratory  infections, which is one of the first things to occur in a suppressed state. To get a biological measure, they measured salivary SIgA , which gives you an idea of how the immune system is functioning and risk of respiratory infections.The goal was simple. To see how the ebb and flow of their training volume and intensity impacted their immune system function and the consequences of having suppressed function (sickness).

Given how we generally think of training, one might expect a linear relationship between these markers of stress and training. In simple terms, you’d expect that the higher the training load, the higher the stress load and the higher the risk of infection.

What’s interesting, though, is that they actually found a non-linear dose-response. Meaning that at both low and high training loads, indicators of stress increased. If the training load was too low, stress, whether from SIgA or responses on the questionnaires, increased. When the athletes had to low of a volume and intensity of work, their bodies reacted in a similar fashion to if they had done slightly too much work.

Too little stress-

The take away then is that while we are used to thinking of too much as being a bad thing in the long term, the opposite is also true.  This may sound surprising, but when we think about it, our bodies are built to encounter stress.

We can look outside of the world of exercise to see the effects of loss of stress. For instance, if we go up in Space and have a zero gravity environment, our bones start to grow weak as our bone mineral density plummets because there is no stress on the bones to adapt. Similarly, while a bit controversial, there’s a reason that brief periods of starvation/fasting tends to increase lifespan in rat models. There’s just a hint of stress there compared to our always eating, comfortable rat. Stress is how we adapt, and too little of it simply means we aren’t adapting.

Even from a psychological standpoint, adversity in life can be seen as a good thing:

“a considerable body of research suggests that moderate stress can promote resilience and that being sheltered from all adversity may not be such a good thing.” Other side of normal pg. 121

We all know this is innately true, whether we look at exercise, diet, life, or any number of places. There’s a piece of research that suggests even in elite athletes, “Talent needs trauma.” The researchers have made the argument that too comfortable of an upbringing, too straight a path to the top, prevents optimal growth and development.In one such study, researchers concluded:

“contrary to the popular pyramidal concept of athlete development, a single linear assault on expertise is rare, and that the common normative junior to senior competition transition is mostly characterized by complex oscillations featuring highly varied transitions.”

In other words, if it’s too easy, they aren’t growing.

So what?

The point is this, while there’s an optimal challenge window, and while going beyond this window is likely more risky and perhaps more damaging, not doing enough also can be dangerous.

What’s this mean in terms of training? Well, a period of time off is likely less beneficial than a period of time jogging around and doing just enough to keep things going. Perhaps we could extend this to recovery and realize that maybe a short easy 5 mile run helps us more so than a day off?  I don’t have the answer to the question and much research needs to be done, but it’s an important concept to acknowledge and consider.

I’ve always had this pet theory that big shifts cause the body to overreact. So if we took a person running 100mpw consistently and dropped him/her to 35mi in a week, his body almost goes into hibernation like state because of such a dramatic shift.  Same
thing if we go from banging out 2-3 hard workouts a week and then do almost nothing hard the week of a major race.

We have this tendency to overreact and send the signal to our body that we are resting. When the reality is we need to send the signal that we are priming it to be ready. That means of course a drop in training volume/intensity/density, but perhaps not so much that it causes this increase in stress that we saw in the aforementioned study. Our bodies, in this case the immune system, overreact.In a strange weird way, the running 70 mpw with 2 hard workouts and a long run, has become the bodies new homeostasis. It’s the new norm off which the body is used to functioning. If we all of the sudden deviate from this homeostasis, the body reacts, even if that deviation is from decreasing the training load. A stimulus is a stimulus regardless of what direction it’s applied in.

It’s all about finding this sweet spot.


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    1. -OOJoe on December 23, 2015 at 12:45 am

      Interesting, but many questions on the "u-shaped" outcome study, namely: how did they control for non-training stress? Life stress? Pre-championship competitive anxiety? This study took place in a five-week run-up to nationals, where the lowest TL was the week preceding the tournament (in which they lost, finishing second).

      If they failed to control for non-training stress and anxiety (such as measure >six weeks out with a very low TL), there's no way you can infer low TL (alone) correlates to higher physiological stress markers.

    2. Stuart Warner on December 23, 2015 at 3:13 am

      Two questions in light of your blog. First, is there any good literature on tapering? Second, since tapering for a marathon is usually rather prolonged, what is your current thinking (which will soon have an important application) about such a taper? I think of both Shorter and Salazar, both of whom ran great 10000s (in Shorter's case two) a week before great marathons.

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