Have you ever found yourself feeling weak, unmotivated, and scattered after a workout? And not just in the hours following the workout – even in the following day or two?
But what gives? Isn’t exercise supposed to energize us and make us feel amazing?
You go in, do a fantastic workout, and then it hits you: brain fog, fatigue, and weakness.
The following day is challenging, and you feel like crap, despite being diligent with your nutrition and general recovery.
A reader of Pump Some Iron, Vito G, recently brought this topic to my attention and I can relate. I experience this on almost a weekly basis.
The question is, why does this happen? More importantly, is there something we can do to prevent it or, at least, lessen the effect?
Let’s find out.
What Makes Our Training Effective And Practical?
For our training to be effective, it needs to cause significant enough disruption.
You see, the human body is an incredible machine, capable of adapting to all sorts of stressors. When you first began training, you probably noticed that you weren’t capable of much and could only lift the bare minimum, and with poor technique. But then, thanks to adaptation and increasingly higher stress, you were capable of doing more and more.
Today, you can probably warm-up with the weights that were once your best lifts without thinking about it. And this is one fascinating thing about adaptation:
Once your body has adapted to some stress, it can handle it with less effort. For example, the first time you bench press 135 pounds, it might be your one-rep max, and it might take you upward of five minutes to recover from that. Fast-forward a couple of years, and you might press 135 pounds for an effortless set of ten while warming up.
On the one hand, this is great, and it means that you’ve become more capable. But, this also means that what previously challenged you no longer does. You need to introduce more stress to cause further adaptations (strength, muscle growth, explosiveness, etc.).
For us to keep improving, we need to cause larger and larger disruptions. That way, the body has no choice but to improve in some way. The problem is, finding the bare minimum of effective work is challenging. Most of us do more than we need to. As a result, we progress, sure, but we also pile on unnecessary levels of fatigue.
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The Stimulus-Recovery-Adaptation Link
“Disturbance to the state of an organism is the driving force for biological adaptation.” (1)
All positive adaptations boil down to two fundamental things: causing an adequate stimulus and allowing the body to recover afterward. The stimulus-recovery-adaptation (SRA) curve represents that quite well. As we impose physical stress on the body (eg., by training), it responds by recovering. Once recovered, the body makes adaptations that serve as reinforcement and allow us to handle the same stress level better.
For example, the first time you train legs, you cause significant disruption. Your legs are weak and sore for days, and your body is in a state of recovery. But then, as you train your legs a few more times, you notice two things:
1) The workout doesn’t cause nearly the same disruption, and your lower body remains a lot more functional than it first did. Even if you feel soreness and fatigue, it’s not nearly the same as it was at first. The repeated bout effect partially explains this – the more we expose the body to a given stimulus, the less that stimulus disrupts homeostasis.
2) You’re able to do more work before feeling that same level of tiredness. You can do more exercises, more sets, more reps, all while lifting heavier weights. In essence, you’ve raised your athletic capacity, and your body has also become more resistant to stress (which isn’t necessarily good if your primary goal is an adaptation).
This happens when you train within your body’s ability to recover in time. In essence, the normal cycle of training and recovery looks like this:
We train (A) ⇒ We become fatigued (B) ⇒ The body enters a state of recovery (C) ⇒ We experience a supercompensation effect (D)
A – Training causes physical stress to the body.
B – We leave the workout in a weaker and more vulnerable state.
C – Recovery allows our muscles to recuperate and our body to adapt to the training stimulus.
D – Aside from the expected recovery we experience to return to baseline, we also see a supercompensation effect. We become better able to handle the same type of stress in the future, thanks to positive adaptations (i.e., muscle growth, strength gain, etc.).
If we skew some training variables (which we’ll look at in the following points) and make our workouts too challenging to recover from, we run into trouble. The stress we impose on the body is too much to recover, and we enter a cycle of under-recovery.
Instead of causing a stimulus, recovering, and experiencing a supercompensation effect, we play catch up. The supercompensation effect cannot occur because the physical stress we’ve generated is too great, and the body needs more time and resources to return to baseline, let alone adapt positively.
Let’s take a look at some training variables and how they can impact the SRA curve.
Training Variable #1: The Stimulus to Fatigue Ratio
Mike Israetel came up with an interesting concept: the stimulus to fatigue ratio. This refers to the stimulative effect an exercise can have on us versus the fatigue it causes.
For example, contrary to popular belief, the deadlift offers a poor stimulus to fatigue ratio for overall back development. Sure, the deadlift can build up the back, but at what cost?
After a few heavy sets of deadlifts, most people find themselves incredibly tired, and the rest of their workout typically doesn’t go as well. At the same time, however, the back muscles aren’t stimulated enough for optimal hypertrophy.
One reason why that is has to do with the demanding nature of deadlifts. Picking a heavy object off the floor is challenging physically and psychologically. Most lifters need to deadlift well into the hundreds of pounds for the exercise to make an impact, and that can be draining.
We also need to account for the fact that deadlifts train many other muscles aside from the back: your arms, shoulders, grip, core, glutes, hamstrings, and, to a degree, your quads. Aside from the acute fatigue you feel from this exercise, you also need longer to recover afterward. This could be one possible reason why we feel incredibly tired after training.
If this sounds like I’m trying to build a case against the deadlift, it isn’t. I’m using it as an example, and if you enjoy doing it and it aligns with your goals, by all means, don’t stop. But, recognize that each exercise has a unique stimulus to fatigue ratio, and our exercise selection plays a significant role in how effective and draining our workouts are.
Two seemingly identical workouts can have vastly different outcomes regarding their overall effectiveness and the fatigue they cause. For example, consider these two examples of back workouts:
Conventional deadlifts – 4 sets of 4 to 6 reps
Pull-ups – 4 sets of 6 to 10 reps
Barbell rows – 4 sets of 8 to 12 reps
Inverted rows – 4 sets of 10 to 15 reps
Barbell rows – 4 sets of 6 to 12 reps
Lat pulldowns – 4 sets of 8 to 12 reps
Seated cable rows – 4 sets of 10 to 15 reps
Cable lat pullover – 4 sets of 12 to 20 reps
Who could argue that either workout is ineffective? However, upon closer inspection, workout A seems to be a lot more demanding and fatiguing than workout B. As far as their effectiveness, both appear to be great.
Further Reading: Here is a list of deadlift related articles on Pump Some Iron (just to prove I’m not anti-deadlift :))
- How the Deadlift Will Change Your Body for the Better
- Trap Bar Deadlift: The Best Full Body Exercise for Almost Everyone
- The Benefits of Using a Deadlift Bar VS Stiff Bar for Deadlifting
Training Variable #2: Training to Failure
Training to failure is among the more controversial topics in training for muscle and strength gains. On the one hand, we’ve got the many advocates of training to failure who state that we need to push ourselves to our limits if we could ever hope to make good progress. On the other hand, there are the folks who suggest that training to failure is too fatiguing and dangerous.
Let’s take a look at some research here. In the first study, researchers examined the effects of training to failure vs. nonfailure over 11 weeks (2). Once the trial was over, researchers put all of the subjects on an identical 5-week peaking period of maximal strength and power training. Researchers also wanted to examine the basal circulating anabolic and catabolic hormones.
In conclusion, researchers found that both groups gained similar strength, strength-endurance, and power. In their words:
Briefly, this investigation demonstrated a potential beneficial stimulus of resistance training not leading to failure for improving strength and power, especially during the subsequent peaking training period. However, training leading to repetition failure seemed to more beneficial for enhancing upper body local muscular endurance.
A more recent study also looked at the importance of failure training on muscle and strength gains (3). The authors concluded that both failure and nonfailure training lead to similar improvements and that pushing to the limit may not matter for optimal results. However, the researchers did point out that sets need to be taken close to failure if we are training with incredibly light weights.
Now, let’s look at a study that better aligns with our concerns: how training to failure affects our post-workout recovery. In one study, researchers examined failure and nonfailure training and their effects on post-training recovery (4).
They found that failure training significantly slowed down recovery and hindered athletic performance for longer. In their words:
RT leading to failure considerably increases the time needed for the recovery of neuromuscular function and metabolic and hormonal homeostasis.
None of this is to say that training to failure is worthless or harmful because it isn’t. Taking some sets to failure can be beneficial, and it can help us achieve better results in the long run. But, taking most sets to failure can be counterproductive, as we saw from the above studies.
Aside from the slower post-workout recovery, pushing ourselves too close to our limits can also lead to the well-known post-workout fatigue and cognitive impairment.
Personally, I train “DC Style” (High intensity / Low volume) for most muscle groups. I only take 2 sets to failure per exercise and only do 1 to 2 exercises per muscle group per week. In order to prepare for my 2 “working sets” I do 2 to 3 warm up sets which are not taken to failure.
If you have an extra hour to spare, below is a great video where Jordan Peters and Mike Israetel discuss training volume, training to failure and “reps in reserve”
Training Variable #3: Training Volume
Training volume – the amount of work we do in the gym – is arguably the most critical factor for muscle growth. According to research, the more work we do, the better our progress is. This is up to a point, of course, because doing too much work can have the opposite effect – problems with recovery, regression, and the overtraining syndrome.
For example, according to one recent review on high volume training, the optimal hypertrophy range has been suggested to be between 12 and 28 sets per muscle group per week (5). To anyone who read the review, this recommendation will be clear enough:
Even if taking a high volume approach, you should start on the lower end and progressively increase the amount of work you do over the weeks and months. Give your body adequate time to get used to the amount of stress and avoid doing more work than you need to progress well. In other words, this guideline is like a ladder to be climbed, and lifters should take incremental steps up.
Many lifters see the recommendation of 12 to 28 sets per week as 26 to 28 sets per week. The thinking goes, “If some is good, then more is better.” But that isn’t always the case.
Training volume should increase only after you notice that progress has slowed down. For example, if you used to make good progress on 12 sets per week but now see that you’re stalling, then bump it up to 13 per week and go for another few weeks.
Making large and sudden increases in work volume can lead to recovery issues, which inevitably impact cognition, energy, and more. Plus, even if you haven’t made large increases in volume recently, it’s worth thinking about your current training volume. More specifically, would it be possible to make the same (or similar) progress with less work?
Delayed-Onset Brain Fog – Is There Any Scientific Backing?
In the early 1990s, Kent-Braun et al. came out with an interesting paper on chronic fatigue syndrome (CFS) (6). The researchers hypothesized that the physical symptoms of fatigue in CFS were, in part, related to the central nervous system’s perception of how the body responds to a given stressor. They suggested that chronic fatigue syndrome didn’t cause real muscle fatigue but impacted the nervous system, which created a feeling of fatigue.
They went out to test their hypothesis by having subjects with chronic fatigue syndrome contract specific muscles after prolonged exercise. They found that the subjects failed to activate their muscles, despite a lack of physical exhaustion of these muscles (e.g., muscle damage, metabolic stress, and such).
These interesting findings suggest that bodily fatigue can be perceived mentally rather than being present physically.
While the research is done on subjects with chronic fatigue syndrome, it points to something interesting. Namely, perceived fatigue and actual exhaustion may not always be the same. In other words, the body may have protective mechanisms for conserving energy.
From an evolutionary standpoint, this makes sense. Calories used to be a lot more valuable and food used to be a lot more scarce back in the day. So, the body had to develop mechanisms for down-regulating activity to preserve as much energy as possible to ensure our survival.
Of course, this is speculative, and there is no research to back this hypothesis up. But it points at an interesting idea:
The fatigue, lack of motivation, and even brain fog we experience after training may not necessarily be entirely due to physical exhaustion.
Can Brain Fog Occur From Other Things?
The relationship between stress and fatigue is nuanced, and many different things can impact it. Furthermore, how fatigue manifests itself can also vary from person to person. Take, for example, the overtraining syndrome. Falling into a state of under-recovery can lead to a variety of symptoms, and most people typically experience some combination of them:
- Brain fog
- Inability to sleep well
- Lack of motivation
- General weakness and fatigue
- Pains and aches
- Getting sick more often
- Loss of appetite and digestive issues
- Loss of sexual drive
In general, this delayed-onset brain fog many people experience can be caused by different things. For example, hydration is vital for cognition, energy, and athletic performance. If you’re dehydrated, that could lead to general fatigue.
Another factor is your nutrition. If you’re in a calorie deficit, your recovery will be somewhat impaired, and feeling tired after training is to be expected. Consuming enough carbs and protein is also vital as both nutrients play a role in our recovery and overall energy levels.
Glycogen depletion can play a role, but we don’t have any research to support this idea for now. What you can do is try different training styles and see how they impact you afterward. For example, if you feel crappy after a low-volume high-intensity workout, glycogen depletion is probably not to blame.
Central nervous system fatigue is another factor to consider. Research shows that CNS fatigue is real, and it can lead to these unfavorable effects (7).
With all of that said, the general fatigue and mental fog we experience after training could be a trade-off of training hard and pushing for progress. After all, the body is weaker, and it actively puts calories into recovery and adaptation. If that is the case, we can’t do much about it except sleep, eat well, and let time pass (8, 9).
What Can Mental Fatigue Tell Us About Our Training And Life Stressors?
Mental fatigue after an intense workout doesn’t necessarily mean anything. We all feel tired from time to time, and having the occasional day where you don’t feel well isn’t necessarily alarming. But, if this turns from an isolated occurrence to a pattern, you might want to reconsider your tactic.
Fatigue and mental tiredness after training can be a sign of too much stress – for example, the physical stress from exercise. In other words, this could be a sign that you’re doing too much work or are pushing yourself too hard on each set.
Consider the question, “Can I progress well while doing less work or by leaving a bit more in the tank on each set?” In many cases, the answer is yes. While it may sound counterintuitive, we often don’t need more work to make good progress.
Another question you might want to consider is, “When was the last time I took it easy for a while?” The topic of deloading isn’t incredibly exciting, but regular periods of easy training (or none at all) are critical because stress is cumulative. Over the weeks and months, it adds up, and we feel tired and more worn out without even realizing it. As a rule of thumb, it’s good to take an easy week for every six to ten weeks of serious training.
What Can We Do to Prevent (or Lessen) Delayed-Onset Brain Fog?
At this point, you’re probably wondering, “Well, is there any way to combat this, or do we have to deal with it?”
Training is stressful to the body, and it causes significant disruptions. If we want to grow and improve, some degree of discomfort is inevitable. But, this doesn’t mean that we should crawl out of the gym or that we should feel like crap for the entire day following a scheduled workout.
Here are some simple things you can implement into your life:
One of the most important things you need to do to make your training productive is to tune your volume, training intensity, and frequency. General guidelines do a good job of giving us a starting point. But we have to experiment then and tweak the variables one by one to see what works best for us.
For example, some people do better with a higher frequency, while others don’t need to train more than three days per week. Some folks prefer a lower intensity of training, while others prefer heavier weights.
Don’t Take Every Set to Failure
Training to failure is a great way to puff up the ego and feel like our training is more productive. But, according to most research, training to failure across all sets isn’t needed and can prolong our recovery time (4).
For example, you can take more sets to failure on isolation exercises like bicep curls. You can also add some AMRAP sets for compound movements, and you can push yourself hard on the final set or two for a given muscle group.
Personally, I stick to 2 sets to failure. These are what I call my “working sets”. They are the 2 sets that I log and the only ones that really matter.
Sleep is one of the most important things we should do to optimize our recovery, energy levels, and well-being. Yet, ironically enough, most people don’t think about it and happily sacrifice it for other, seemingly more beneficial things.
According to research, however, sleep is integral for recovery (10). In the words of the researchers, “Sleep serves an absolutely vital physiological function and is arguably the single most important factor in exercise recovery.”
General guidelines suggest that we should aim for seven to nine hours of sleep per night.
Pay Attention to Your Nutrition
Research is yet to unravel the best nutritional strategies for optimal recovery, but we have bits and pieces that we can use.
For example, protein plays a vital role in muscle protein synthesis and post-training recovery (11). Carbs are also essential as they help replenish lost glycogen, aid muscle protein synthesis, and allow us to recover optimally (12, 13).
Our overall calorie intake also plays a role in how we feel, recover, and perform. For example, if you’re in a calorie deficit for fat loss, some fatigue and mental DOMS are expected.
The topic of hydration is about as exciting as that of sleep. Still, drinking enough fluids every day helps you feel better, remain mentally-sharp, and may play a positive role in post-training recovery.
According to most sources, men should aim for around 100 ounces of water per day (roughly three liters), and women should aim for up to 70 ounces (approximately two liters).
One of the issues with hydration is that our bodies don’t always utilize the water that we consume. In order to properly “absorb” the water and have it rehydrate our cells; salt, potassium and carbohydrates should be consumed along with the water. Vito G, the reader who brought this topic to light came up with a “DIY sports drink” that I have found to be effective.
1 liter water
1/2 Teaspoon salt
1/2 Teaspoon potassium (Morton’s lite salt has both salt and potassium)
8 Teaspoons Sugar or honey.
If you’d rather buy something than do the DIY version. These Liquid IV Hydration Multiplier packets on Amazon are good. They combine salt, minerals, sugar, and B vitamins.
Hopefully, after reading this, your exercise induced brain fog will be a thing of the past.
If you liked this article or want to share your own advice, please comment below.
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