Eric Cressey

Understanding and Managing Fatigue

Today’s article is a guest post by Eric Cressey on not only understanding fatigue, but how to manage fatigue as well.  This is a really interesting topic to me, as “recovery” is probably the next big area we need to really research and optimize so we can enhance performance for everyone from rehab patients, to fitness enthusiasts, to professional athletes.  This is an invaluable lesson that rehabilitation specialists can pick up on from the strength and conditioning world, manage fatigue properly and you’ll see faster outcomes.


Understanding and Managing Fatigue

Perhaps it’s coincidence, or perhaps the scientific community is finally catching on, but recently, there have been several studies looking at the role of short- and long-term recovery in preventing and rehabilitating injuries.

Here’s a research study that demonstrates relationships among a variety of scheduling and recovery factors and injury rates.  The part I found most interesting was that researchers observed that sleeping fewer than six hours the night prior to a competition led to a significant increase in fatigue related injuries.

Additionally, researchers at Stanford recently demonstrated the profoundly positive effect that “sleep extension” has on a variety of performance variables in high-level basketball athletes.

These results, in themselves, aren’t particularly surprising: fatigue impacts performance – whether that’s on the field, or in the rehabilitation realm. Anyone who has ever trained an athlete on a Saturday morning after he’s had a late Friday night, or rehabbed a roofer after he’s completed a 10-hour-workday, will tell you that there are certainly less-than-optimal times to get the work in.

What research like this doesn’t tell us, though, is that not all fatigue is created equal – and I suspect that this is one area where strength and conditioning specialists can “return the favor” to rehabilitation specialists for all that we’ve learned from them over the years. Very simply, the very best strength and conditioning coaches I know are the ones who are masters of managing competing demands, including strength training, mobility drills, soft tissue work, movement training, metabolic conditioning, and sport-specific training. In order to effectively manage all these factors, it’s imperative to understand the different stages of fatigue. On the rehabilitation side of things, every injured athlete likely has some element of fatigue that not only impacted his/her injury mechanism, but will impact the response to a given rehabilitation program.


Over-what? Over-everything!

In their classic review, The Unknown Mechanism of the Overtraining Syndrome, Armstrong and VanHeest discussed the importance of differentiating among overload, over-reaching, overtraining, and the overtraining syndrome (OTS). They defined the terms as follows:

  • Overload – “a planned, systematic, progressive increase in training stimuli that is required for improvements in strength, power, and endurance”
  • Over-reaching – “training that involves a brief period of overload, with inadequate recovery, that exceeds the athlete’s adaptive capacity. This process involves a temporary performance decrement lasting from several days to several weeks.”
  • Overtraining – training that “exceeds over-reaching and results in frank physiological maladaptation(s) and chronically reduced exercise performance. It proceeds from imbalances between training and recovery, exercise and exercise capacity, stress and stress tolerance; training exceeds recovery, exercise exceeds one’s capacity, and stressors exceed one’s stress tolerance.” 
  • Overtraining Syndrome (OTS) – “a set of persistent physical and psychological symptoms that occur subsequent to prolonged application of heavy training loads. The critical diagnostic factor is a chronic decrease in performance, not simply the existence of SAS [signs and symptoms].”

Overload is inherent to a successful training process, and over-reaching is actually quite valuable when used appropriately. For instance, in our training programs at Cressey Performance, we generally fluctuate training stress in four-week programs as high (1), medium (2), very high (3), low (4), where the deloading in week 4 allows for adaptation from the fatigue imposed during week 3.

However, over-reaching is far from overtraining – a term that is thrown around far too often among even the most qualified individuals in the world of health and human performance. Over-reaching may be attained in as little as 7-10 days, and remedied in a matter of days or weeks with adequate deloading. Conversely, the process of overtraining must take place for months for the outcome, OTS, to be apparent. Recovery from OTS requires at least several weeks – and more often several months; in other words, you really have to go out of your way to get to overtraining syndrome.

Since high level performance – and even just normal physical health – is a priority, it is imperative that coaches, parents, and athletes recognize the signs and symptoms of over-reaching and overtraining syndrome – and the differences between the two. According to Armstrong and VanHeest, the signs and symptoms of OTS may include:

  • Decreased physical performance
  • General fatigue, malaise, loss of vigor
  • Insomnia
  • Change in appetite
  • Irritability, restlessness, excitability, anxiety
  • Loss of body weight
  • Loss of motivation
  • Lack of mental concentration
  • Feelings of depression


What All These “Overs” Mean to You

Many of these signs and symptoms are shared between over-reaching and OTS, so how do we know the difference? How do we know when to hold back for a day or two (for overload recovery), 7-21 days (over-reaching), or even months (overtraining syndrome)?

Unfortunately, as much as I would like to be able to offer you the magic answer, I can’t do so. The scientific community has yet to agree on a single, highly sensitive diagnostic test to differentiate among the three.  In fact, the only diagnostic tests that are universally accurate are those of physical performance; if performance drops off, there must be some degree of accumulated fatigue.

Other measures – such as heart rate, bloodwork, metabolic rate, substrate metabolism, and a host more – are subject to so many factors that they are hardly reliable tests of one’s training status.

As an example, research from Fry et al. had subjects perform ten sets of one repetition on machine squats at 100% of their one-rep maximum for 14 days straight. That’s an absurd volume of high-intensity resistance training, especially in a trained population. You know what, though? The only thing that dropped off was performance; hormone status (as measured by bloodwork) really didn’t change much at all.

Conversely, crush an endurance athlete with volume, and this same bloodwork will look terrible. The take-home point is that it’s a lot harder to “overtrain” on intensity than volume. And that’s where the problem exists when you’re dealing with athletes: just about every sport out there is a blend of volume and intensity. We don’t just train or rehabilitate shotputters or Ironman competitors; we get athletes from soccer, basketball, baseball, hockey, tennis, and a host of other sports.

So, what is a coach or rehabilitation specialist to do when trying to determine just how much fatigue is present, and what the best course of action is to guarantee an optimal return-to-play as quickly as possible?

In two words: ask questions.

In my opinion, the absolute most important step is to establish communication with athletes and – in this case – patients. Ask about training practices before an injury, sleep patterns, dietary factors, family life, concurrent illness/injury, changes in body weight, and appetite.

These may seem like obvious questions to ask, but we live in a one-size-fits-all world of pre-made templates and rigid systems – and people can fall through the cracks all the time. My experience has been that those most commonly “thrown under the bus” in this regard are the most dedicated athletes forced to train or rehabilitate in a “general health” world. As an example, we had an adult athlete client request a Vitamin D test from a primary care physician last year, and he was turned down because he wasn’t “a post-menopausal female.” As it turned out, he was severely clinically deficient, and normalizing his Vitamin D was a big game-changer for him.

Simply asking the right questions will always help the cause when it comes to determining just how “systemic” what you’re dealing with really is. And, in the process, it gives you an opportunity to show a client or patient how much you care before they even care how much you know.


Eric CresseyEric Cressey, MA, CSCS is the President of Cressey Performance, a Boston-based facility specializing in baseball development.  He publishes a free daily blog and weekly newsletter at Cressey and Reinold collaborated on Optimal Shoulder Performance: From Rehabilitation to High Performance.  If you liked this article on understanding and managing fatigue, you’ll love Eric’s website.

19 replies
  1. carl valle
    carl valle says:

    HRV and Cortisol have relationships but remember not to forget about circadian rhythms and nutrient timing. I believe that breathing is part of the picture but when time is at a premium we can’t isolate problems or take out the needed variables.

  2. Mike T Nelson
    Mike T Nelson says:

    Not sure if you were asking me or the other Mike here, haha! I would look forward to his and other responses too.

    I have used grip to determine training and it works quite well. For overtraining I think it can work too, but I would combine it with HRV at a min. I have used grip measurements to help determine day to day changes. You don’t see a huge difference in it, but I have it can be useful in most athletes for exercise selection.

    There was one study that looked it related to squat speed I believe, and I would have to look at the full study again since my memory is fuzzy on what they found. Grip was measured before hand though and squat speed was measured with and without bands using force plates. I should remember more since I know the researchers and I was in the study–ha!

    I hope that helps a bit, and open to thoughts from others.

    Rock on
    Mike T Nelson PhD(c)

    J Strength Cond Res. 2010 Nov;24(11):2944-54.
    Acute effects of elastic bands during the free-weight barbell back squat exercise on velocity, power, and force production.
    Stevenson MW, Warpeha JM, Dietz CC, Giveans RM, Erdman AG.

  3. Peter Fabian
    Peter Fabian says:

    Just spoke with an athlete who had really high cortisol levels and a high HR response with high exertions levels. He did work with one of John Doulliard’s people. Did this Ujjayi breathing while learning to monitor and self regulate his HR response. He normalize his cortisol levels and can now keep his HR at much lower training levels. Wrote an article about his regimen on He also has trained using the Heart Math emWave2 which deals with HRV

  4. Tim Enfield
    Tim Enfield says:


    Thomas Kurz in his book “Science of Strength Training” suggests that we take into account pulse rate, body temp, breathing frequency, weight, blood pressure and among other things, hand grip dynamometry. After reading old translated russian texts, I know these countries believed that if your grip measurements decreased after a high volume strength phase from a standardized normal value that their athlete’s were over-trained. Anyone used this measure with any reliability or success? T

  5. Mike T Nelson
    Mike T Nelson says:

    Great article EC as it is a very confusing topic for many.

    I would agree wtih Carl, that HRV is great, but it is only ONE component and not the entire picture.

    How the HRV analysis is run can make a pretty big difference too. I am biased towards nonlinear methods.

    I have checked into the Omegawave and had an analysis done on myself quite awhile back. I find the concept facinating and if they want to drop one off at my place, I would love to experiment with it! The downside is it is very spendy and it also as Mike mentioned a black box—who knows how it really works! For $35K and beyond I just can’t see myself spending that kind of coin on it any time soon.

    Good discussion everyone!
    Rock on
    Mike T Nelson PhD(c)

  6. carl valle
    carl valle says:


    Local fatigue and repair status (muscle and other tissues) can be viewed with elastography and EIR methods. Who has time for that I don’t know.

    What does the Redsox use now Mike?

  7. carl valle
    carl valle says:

    HRV has limits but it’s been researched for sports performance for years. In 2004 in Stockholm a group of world leading experts in Sport Science shared some interesting HRV information.

    HRV is system fatigue and specific local fatigue (one muscle group in the left leg for example) and that data is related to sleep duration. Sleep quality is related to training load.

    Does anyone think that Terry Francona is going to adjust line-ups based on HRV scores and vibromyography charts? Not likely.

    What data collected daily are people collecting really? If you are a strength coach and work with athletes 3 days a week inseason what about the other 4 days?

    Very few pro athletes keep training logs…..except in Europe and Down Under.


  8. Sam Leahey
    Sam Leahey says:

    HRV is a huge topic that eastern European coaches have been talking about for years. It has absolutely been linked to performance. From what I can tell, SPORTDiscuss research database should give you all the information you need to validate said link. Joel Jamieson, Mark McLaughlin, and Dave Tenney have been using the OmegaWave for years with wonderful success. It’s super pricey (35k I think) but the ithlete is a great (much less expensive) alternative and not nearly as high-tech.
    Lastly, I’ve written a short blog post series on this exact topic that should give you plenty of practical ideas:

    Autonomic Nervous System Part 1:

    Autonomic Nervous System Part 2:

    Autonomic Nervous System Part 3:


  9. Mike
    Mike says:

    I have used Ithlete for quite a while. Mainly as a background tool for my own programming. Its does indicate when my fatigue accumulates higher and higher. My values also drop significantly if I get poor or too little sleep, and shortly before I get sick it drops. It is a good tool I feel, but is not a fool proof guide of TRAIN/DO NOT TRAIN today. Also it costs more than ten dollars, it is $50. Which includes a dongle that you plug into your ipod or iphone and the app itself that you download. I would love to chat with anyone else that has used this. I know that Landon Evans at ELITEFTS has also been experimenting with ithlete .

  10. Eric Cressey
    Eric Cressey says:

    Eric – My experience wasn’t as extensive as Mike’s, but my take-home impression wasn’t much different. I’m not a fan, based on what I’ve seen and heard of folks who’ve used it.

  11. Eric
    Eric says:

    Great article on a tough topic. What’s your view/experience with the Omega Wave system? It claims to have a pretty sensitive algorithm for detecting fatigue and CNS readiness, and I know a few other coaches are big fans of it. Not sure how or even if it’s been scientifically validated though.

    Personally, I fear a tool like that would give coaches an excuse to stop listening and thinking, even if it does measure what it claims to. Regardless, it’s an intriguing device. Thanks.

    • Mike Reinold
      Mike Reinold says:

      I have personally used the Omega Wave system briefly and looked into it a bit. The company was not willing to share much information to me regarding the “why” or research behind the device. What I found was that it was basically a comprehensive way to assess heart rate variability. I am sure it may do more, but that is what I took out of it. I am sure we will learn more about this over time.

      HRV hasn’t been linked to performance just yet, but there may be an association with fatigue and over training.

      I’m not sure yet what the best method is of measuring HRV (other than ECG), but I am not sure Omega Wave is the way to go. I am not a fan of a company that won’t tell you about their product, what it does, and what the research is behind it.

      For what it is worth, there is a $10 iphone/ipad app that is supposed to measure your HRV, called “ithlete.” Has anyone checked that out?

      I wouldnt recommend using this knowledge obtained to do anything other than optimize your training and recovery techniques. See what is causing overtraining and what you can do to help with that, rather than deciding if guys can train that day or not. Just my thoughts.

      • Tim Huntley
        Tim Huntley says:

        Hey Mike,

        I have been using a combination of a Suunto t6d heart rate monitor, software from Firstbeat, and shareware from Kubios – all totaled, about $300. With this, I am taking daily HRV measurements, not so much to determine overtraining (I agree with the comments by Carl and Mike below), but more to see the effects of a vigorous exercise program on modifying/improving HRV parameters over weeks and months.


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  3. Fatigue | ibodybuilder says:

    […] 1) A new article from Mike Reinold shared by Eric Cressey regarding managing fatigue attracted my attention to this under-discussed issue of fatigue, especially training through fatigue: Understanding and Managing Fatigue | Mike Reinold. […]

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