I think athletes often pursue a state of tiredness and soreness as a validation of training. Walking around with sore legs? That means you’re doing enough. Tired during runs? Heck, yes, you worked hard for that. I don’t think that’s the best approach for most athletes.
Here’s my rule for athletes: if you’re tired for more than 36 to 48 hours, back off training until you feel good again. Let’s call it the Lizzo Standard: training should feel “Good As Hell,” even if it means you are doing less work over time than you could otherwise.
Now, the boatload of disclaimers that come with any article I write. I’ll be using the word “fatigue” throughout this article interchanged with other terms like “tiredness” and “soreness,” but I’m not talking about performance-related fatigue like in a race or training session. For more on that and this topic generally, buy three copies of Endure by the amazing Alex Hutchinson (one copy for you, one copy for a friend and one copy just so Alex gets the supersized royalty check he deserves). Instead, I’m talking about day-to-day tiredness, lack of snap on runs, and just the general feeling that the training work requires lots of … work. Tiring, tiring work.
Know Your Baseline
Every athlete is different. My guess is that some elite athletes can withstand much higher loads of sustained fatigue and still adapt long-term, whereas other athletes are close to the edge even when they are playing it safe. Know your background and your baseline. We’re looking for deviations from normal, trying to calibrate your normal to whatever the Lizzo Standard means for your physiology and psychology.
Plus, there are times in training where sustained fatigue may be part of the goal, like in overload phases of race-specific builds, after supercompensation stimuli like beast-mode marathon workouts or training races, and consecutive long runs for ultrarunners. When you step things up to reach the next level, that may come with some extra fatigue, but don’t let that become the new normal.
Otherwise, I think that sustained fatigue can be counterproductive for most athletes. What we think is building us up is actually holding us back. Do less to achieve more. Six-minute abs and 5-minute meals and 4-hour work weeks.
Wait, not those last things. But I can understand if those lifehack-shortcut articles are where your mind went as I started talking about training-related sustained tiredness being bad.
I am not saying that I don’t want athletes to work hard. I really, really do. Work your freaking butt off like the elite athlete you are. Instead, I want you to think about adapting to the hard work you are doing. Fatigue can be a proxy for stagnation and regression. And it can make life a real freaking drag. Let’s break it down.
What do you mean by sustained fatigue/tiredness?
At one end of the fatigue spectrum is being 100-percent race ready, like you’d aim to be at the start line, the Lizzo Standard gold medal. At the other end is full-blown overtraining syndrome, the mind-and-body implosion that is the culmination of too much stress. A 2012 review article in the journal Sports Health details the neurologic, endocrinologic, immunologic and mood-related perturbations from OTS. This article is not about OTS, which impacts the nervous system, cognitive function and every aspect of being a sentient, bipedal organism.
Instead, this article is about more subjective fatigue in everyday life and runs—feeling a bit tired moment-to-moment. Here’s the most important thing to remember: even before tiredness progresses to full-blown OTS, there are impacts to cognition, behavior, mood and performance, as discussed in the 2012 article and a new 2019 article in Biology Letters. That journal title doubles as a good re-branding for the Penthouse Forum.
In life, excess fatigue might be heavy eyelids for no good reason, lack of motivation or being a bit slower on the uptake at work. In running, think heavy legs, like you’re sticking to the ground a bit, needing lots of time and effort to feel good each day. Many studies evaluate fatigue through qualitative surveys, and that’s what I’ll ask you to do in an informal way by the end of this article.
While it’s easy for athletes to portray those feelings as a mental weakness, they usually have a physiological basis outside the confines of the brain. One 2016 case study in the journal Physiological Reports looked at how an elite German training camp quantified load management in athletes. That study looked at daily measurements of oxygen saturation of hemoglobin, resting heart rate, body mass, body and sleep perception and capillary blood concentration of creatine kinase. Every other day, they measured venous serum concentration of blood urea nitrogen, venous blood concentration of hemoglobin, hematocrit and blood-cell counts. If two or more values showed abnormal deviations for that individual athlete, then training load was reduced.
Here’s the kicker. Running economy improved for those athletes on a strict load-management routine, and “no athlete showed any signs of underperformance, chronic muscle damage, decrease body and sleep perception as well as activated inflammatory process during the 21 days.” They were healthy, happy, fast as crap and getting faster all the time.
Would that have worked over longer training cycles, or for different types of athletes? That’s tough to measure in a study, but my guess is that it’s OK to throw that healthy physiological equilibrium off balance in extreme moderation for the body to have some long-term adaptations. But it needs to be accompanied by plenty of recovery (rest, sleep, food) to avoid chronic issues.
Other studies have shown correlations between some of those biomarkers (particularly those related to inflammation and oxygen-processing ability) and fatigue/tiredness levels, along with stress. So when thinking about tiredness/soreness in this article, it’s not a question of “how bad do you want it?” It’s “What is the objective state of your physiology and how can we tune into that to optimize performance, health and happiness?”
Why can sustained fatigue/tiredness be bad?
This is where some coaches and physiologists may differ depending on perspectives. Training to optimize performance necessarily causes some subjective fatigue. It will impact biomarkers as well, at least in the short term. That is the “stress” in the stress + rest = adaptation equation. Theoretically, pushing into that zone can cause adaptation beyond baseline. Do that in hundreds of micro-cycles and dozens of macro-cycles over years, and an athlete begins to explore their potential.
There are three potential problems with pursuing fatigue/tiredness as a proxy for training value. Yes, this is about to become a third-grade-style persuasive essay. If I could get another crack at it, I am somewhat confident that I would totally wreck the elementary-school curve.
First, a little bit too much stress is highly risky for health. Most injuries and instances of burnout happen in slightly overstressed times. If you’re pushing the threshold consistently, it’s tougher to stay on the healthy side of the stress-and-rest equation.
Second, and here’s where things get a bit more interesting to me, a lot of training design is about improving running economy—making outputs take less effort. A 2015 review in the journal Sports Medicine goes over the running-economy basics, but the main takeaway is that everything plays a role, from training to biomechanics to mood to all of those biomarkers we talked about. In states of excess fatigue, athletes obviously have trouble putting out efficient effort. We all know that feeling, where it just takes a bit more oomph to make it happen. That’s likely not great for running-economy development. Working harder to make less happen is not an adaptation you want to reinforce most of the time (though there are exceptions in heavy training for some training approaches).
The more compelling and interrelated point to me is that athletes that often find themselves in fatigued states may have trouble putting out efficient effort even when they feel better later. Here, we’re getting back to the biomarker explanation of fatigue. Even if the mind recovers and the body seems ready, many of the biomarkers impacted by hard training have a long tail, where it takes more than a single rest cycle to restore normalcy, long before it progresses to OTS. That’s why the German study did daily measurements—perturbations that manifest as fatigue may impact performance even when symptoms resolve. You can feel good, but if your hemoglobin is low from poor red-blood-cell formation during a previous period of overstress, your body won’t be able to adapt to its potential.
Third, long-term breakthroughs can be constrained by thinking fatigue/tiredness and performance have a causation relationship, rather than just co-occurring for athletes that would be great anyway. Perhaps the most common roadblock I see for advanced athletes is that they think that extra-hard work is the main source of their powers. Fatigue becomes a proxy for that hard work, so fatigue is elevated as a training virtue. They end up chasing the ability to withstand more fatigue, which may be trainable (especially for top athletes), so they perform slightly better while burning themselves to a fine crisp and peaking early.
What if instead of getting crispy, we focus on a simmer instead? That’s where the running economy framework comes in. I want athletes to channel Lizzo and feel “Good as Hell” on runs as much as possible. That’s more fun and sustainable. And from a raw performance perspective, I think that it often creates a physiological context where training is more efficient and uses less energy, letting them build up to breakthroughs over years.
The Lizzo Standard
Put all of that together, and my general fatigue/tiredness standard is 36 to 48 hours. Think about your sleep, how your legs feel, how excited you are to run and all the other thousands of little signals your body is giving you. A random list of questions: Do you feel mentally sharp? Are you excited to run? Do you have tiredness when walking up stairs? Any changes in healthy sexual function? Eating plenty? Sleeping enough? You get the drill.
Some caveats to remember: it’s related to your baseline, not some magical world. Also, fatigue/tiredness sometimes follows a lack of activity or reduced cardiac output from a lack of intensity, so use your common sense too. Finally, all of this is connected to stress, which isn’t just training. Make sure you are eating plenty, getting sleep and loving yourself as much as you possibly can given your brain chemistry.
So each day, ask yourself the question. Do you feel Good as Hell, or at least close to it? It’s fine to be tired one day, that is normal and explained by typical (and desirable) adaptation cycles. Don’t force a hard workout, but you can run and you can even do a workout if that doesn’t tear down your mental health.
If you’re abnormally tired for two days, make sure there is a stress-based explanation, whether that’s a workout or work presentation. With an explanation, you can be more sure there isn’t a systemic issue to worry about. In that case, you can run, but probably just easy (with strides if that’s on the plan). A workout might even make sense for some athletes.
Three days or more? The Lizzo Standard dictates that you rest or run easier.
Beyond three days, consider backing off entirely or even seeing a doctor unless there’s a clear explanation.
Avoid excessive fatigue, and you’ll be a healthier and happier person. And I think there’s a strong argument that you’ll be way faster over time too.
David Roche partners with runners of all abilities through his coaching service, Some Work, All Play. His book, The Happy Runner, is about moving toward unconditional self-acceptance in a running life, and it’s available now on Amazon.