IPF World Champion Bryce Lewis Explains the Relationship Between Fatigue and Performance

On a day-to-day basis, it’s generally understood that our bodies are probably not going to feel the same, especially when it comes to the feeling of fatigue. And when you factor in things like hour-long gym sessions, maximal bouts of energy and effort, the complexity of our daily lives (stressors), then you’re left with a cesspool of factors that can dictate mediocre, good, and great lifts.

These are the reasons why the concept of auto-regulation in lifting is so important and widely used (think RPE scale).

In reality, it’s a tough task trying to figure out how the body is feeling in relation to the intensity we’re pushing in the gym. After all, when should we push, and when should we back off? Then, throw in things like peaking cycles, off-season training, working towards specific training goals (think accumulated fatigue), and now you’re left with even more factors to keep in mind when pushing past normal fatigue levels.

What the Heck Is Fatigue? 

The concept of fatigue and all of the health implications that go into this concept could be explained for days. For this article, and more specifically to lifters, we’re going to focus on how many athletes understand fatigue, and that’s with central and peripheral fatigue.

In April, we wrote an article on the concept of rethinking how we use and understand central nervous system (CNS) fatigue. This is a concept that includes one’s perceptions of how they’re and a weight is feeling towards their performance. Have you ever been in the gym and everything felt heavy, then denoted it right away as CNS fatigue? While that’s not technically inaccurate, it’s also not really the full story. More than likely, that general sore, slow, and heavy feeling you’re experiencing with your muscles in the gym is actually PNS fatigue, or peripheral nervous system fatigue.

IPF World Champion and TSA Strength Coach Bryce Lewis elaborated on this idea saying, “Fatigue is a complex thing, and the research tends to define different types of fatigue —central fatigue and peripheral fatigue. In my case, I was experiencing a higher amount of peripheral fatigue, where I felt my muscles were sore and achy (essentially higher levels of delayed onset muscle soreness, DOMS, from the previous session).


Central fatigue is more related to general tiredness, lethargy, and feelings of weakness or inability to perform. The fitness-fatigue model shows a general relationship between our ability to perform at a specified task (fitness), and the amount of general fatigue we’re carrying, but the relationship isn’t as straightforward as fitness going up as fatigue goes down.”

When Should We Push Through Fatigue? 

Being someone who tends to be chronically tired and fatigued on a daily basis, I’m always intrigued by how other coaches handle these feelings. Lewis handles multiple athletes and competes at the top level, so I asked when he pushes and backs off — Is there a conclusive line? Lewis provided a ton of insight on this concept.

Keep Your Goals In Mind

The first point Lewis mentioned was about your current training goals and said, I think we need to keep a goal in mind. If I have a competition on the horizon, I know that I need a rough level of overall training intensity and training volume in the weeks and months leading into the competition based on a specified plan.

I know that being fresh leading into every session is not possible and that I will be accumulating some peripheral and even central fatigue. As athletes get to higher levels, this actually becomes the normal state as we need greater amounts of training stimulus to produce further adaptations. It’s just not enough to train while perfectly fresh all the time, or even most of the time.”

Mitigate What You Can and Have a Plan

Outside of a goal, fatigue can still add up. For this reason, Lewis recommended taking control of what you can and to use appropriate recovery tools saying, “Still, it’s a good idea to mitigate soreness by using many tools, as soreness itself decreases our ability to perform the lifts safely and effectively. This is why we design smart training plans that spread fatigue, limit athletes going to failure, encourage good nutritional habits like adequate caloric intake and protein intake, and optimize sleep and stress reduction to the best of the athlete’s ability.

I don’t think we need to get crazy with specifying an answer here, but I think if you can complete the work given within a range of expected difficulties, we’re good. Usually on top of a designated training plan, we also define a range of RPEs, like RPE 6-8.5, that an athlete works in. If the work falls out of that range because of central or peripheral fatigue, it’s perfectly normal and expected for the athlete to drop load or volume. Secondarily, any time we need to modify training to keep the athlete safe.”

Give Your Body a Chance

Some days you may be feeling tired heading into a session, but once you get warmed-up things end up feeling okay. Lewis provided an example on this by saying, “One more important concern here. I think that often times you don’t know how things will go until you warm-up. It’s premature to cancel a session because you’re feeling sore until you warm-up and start lifting. Things often feel way better than you might have expected them to, owing that sensation to other training adaptations related more to strength and less to levels of soreness.

I think the level of “when should I push through and just suffer the wrath of feeling sore” may be different for different athletes, relating to what their technique looks like, what level of RPE they tend to respond better to, their mindset when walking in the gym. I’m not sure we can apply one rule that works best for everyone.”

Fatigue and Your Workout Program

A well-rounded workout program will have multiple characteristics to facilitate various training adaptations. For example, as an athlete gets closer to a meet, then there’s often a bigger push to get past the comfort threshold to bring in new levels of growth. This is why working with a coach, using auto-regulation, and having a well-balanced program is of the utmost importance for progress.

On the concept of fatigue management and programming Lewis added, “In the later stages of any training phase, I think it’s okay to push through fatigue to some more or lesser degree. In powerlifting coaching, one thing we’re really after is finding patterns in the data. Sometimes soreness is more from a single off training day or sleep than it is about anything systemic. If it is systemic and it’s reducing training outcomes we care about, its okay to step in and make course corrections.”

Coach and Athlete Relationships Can Be Key

Outside of understanding the program, Lewis also mentioned that the relationship between the coach, athlete, and their workout is incredibly important. He notes, “It’s useful to remember that the coach and athlete both care chiefly about training outcomes and enjoyment of sport — that is, we care about getting stronger and having fun while doing it. If the athlete is sore but performs well, I think we can agree that’s a better option than the contrapositive.

Levels of fatigue will vary in accordance with the training plan, the athlete’s response to the training plan, mitigated by the response to stress, sleep, recovery, nutrition and it’s okay to have variability here across the training year. Ideally, leading into competitions and training tests, we have an athlete with maximal amounts of preparedness (fitness), and minimal amounts of fatigue. It sometimes turns out that in order to keep fitness high, the level of training volume requires some ambient level of fatigue. That’s okay and serves the larger goal anyway.”

Fatigue and Your Training History

As we spend years in the gym training, we begin to naturally gain better understandings of our body and what we’re able to handle. This could be looked at as a macro idea of progressive overload spread across our lifting careers.

For example, two years ago, what did a 5×5 with 80% of your 1-RM feel like compared to now? The weight may be heavier now, but now you’re probably able to gauge what you can handle a lot better compared to two years ago. Although, does our training history influence our fatigue?

Is This Fatigue Normal?

Lewis told me, “I think training history can give you clues to expected responses in similar situations going forward. Say you’ve done 3x5x400 in the past and you felt like it was around an RPE 7-8. Now you’re doing 4x3x400 and finding they feel really difficult, like RPE 9+. Two reps less and it’s harder? Okay, maybe time to take a look at the data. Am I supposed to feel this way right now? Am I close to a training test? Is my level of fatigue just masking my fitness, my ability to perform? How are non-training variables like sleep and nutrition?

Or, hey, I know this is hard but every time I get through this session and keep going on with the training plan, I get really good results once I dissipate fatigue. A lot of times we’re just looking to answer the question “is this normal?” and our training history, if well-documented, can give us some great clues in answering that question.”

Wrapping Up

The next time you’re in the gym and feeling beat up, remember how complex the concept of fatigue is. Before discounting the day and chalking it up as a complete miss, consider your current goals, training state, and mental state, then create a game plan from there. As much as fatigue and performance can seem related, they can also be unrelated, which is why having a well built out auto-regulatory plan can be so important.

Feature image from @bryse_tsa Instagram page.