Feel the Burn?
Updated: Apr 15, 2020
Is fighting through fatigue really helping you get fitter?
This idea of "feeling the burn" might be a catchy campaign slogan if you're running for president, but is it a good basis on which to structure your work out? I'll explain how it can be –– but it depends on how.
There's a lot of misinformation on this topic, so let's get some facts out of the way:
The burn we feel when exercising is caused by an increase in acidity from the accumulation of hydrogen ions, a byproduct of glycogen metabolism, in the muscle (glycogen is the stored energy from the carbohydrates you eat). The exact mechanics of this burning sensation are still not 100% clear, but it does have the effect of forcing us to stop working and allowing the muscle to recover. This function, whether incidental or by design, keeps us from working our muscles to the point of injury.
For many years this burning phenomenon has been falsely attributed to lactic acid (which isn't even present in the muscle) and/or lactate (which is there, but it turns out lactate actually helps to decrease the burn). Lactate can serve as fuel for your workouts, and working out more can increase the metabolic efficiency of this process, thus increasing your endurance.
Knowing these basic facts, it's safe to say that the burning sensation you feel while working out is not aiding your muscle in growing stronger or larger, and is nothing more than a sensation associated with fatigue. The feeling does not in itself indicate you're "working hard enough" and there is not any demonstrable benefit to ignoring that sensation of pain and pushing through it. It's critical to understand that creating stress in the muscle by lifting causes micro-tears to the muscle fibers, resulting in muscle growth and an increase in strength. However, that process is not something we can feel happening. The burn is not indicative of that process, and therefore the burn itself is not what makes you stronger.
So what does is to be gained through fighting through the burn? Adaptation for better metabolic efficiency and more endurance. This is great when you're cycling, sprinting or running up flights of stairs, however it comes at a cost and a risk to push through the burn when doing strength training. There's a lot more support and control required to lift weights safely and effectively, and forcing out reps compromises that support and control. Whether you're trying to get stronger, build muscle, or just gain the myriad of other benefits from lifting weights, fighting through the burn is not necessary to making progress, and you should be using the burn more as a signal to stop, not a signal to push harder.
Simply put, when you're working out and you're feeling the burn, that's what I consider the danger zone. This doesn't mean you can't push the boundary a little bit, but I want you to drop this idea that you're gaining more by fighting the burn.
Say you're doing some overhead presses and you're on rep 12. Your shoulders start burning. You start making some crazy faces... your mental focus might at that point start to falter. Your awareness of how your shoulders are moving is not as acute. Perhaps your awareness of your core begins to falter and you start hyper-extending your back. Now your presses are engaging different muscles. Perhaps it goes so far that you start recruiting the wrong muscles to continue working and now you've pulled a muscle in your neck...
Congratulations! Now you're in pain for a week, you can no longer work out at all and have to do a full-body 180° turn to check for cars when crossing the street. Was it worth it?
As an alternative, I recommend you use that point of fatigue as your signal to STOP working. If you do that consistently, you will still be training your body's endurance, just from a place of safety and control. You will still make progress. You don't even need to do fewer reps or less "work". You can choose a target range of repetitions based on the adaptation you're trying to achieve and then match your weight accordingly so that your "burn point" is within that range. Give your body time to recover between sets and do more sets. The burn serves to slow you down. This is why I recommend tempo work – you find a tempo that's sustainable. When you feel the burn, you're going to start slowing down. At that point, switch it up.
What matters most when we are working out is that we are doing the work. And equally important to that is doing the work safely and effectively. Whether you do the work in 3 struggle-sets or 6 controlled sets, the difference will not be significant. This is especailly true for those of us looking for a well-rounded and balanced strength and fitness. Not everyone needs to be training like a powerlifter.
The key to progress is consistency. The key to consistency is mindfulness, control and discipline. Not just in showing up to the gym and doing your workout X times per week –– but throughout the whole workout, in every repetition. Every movement should be given your full attention and your technique should always be focused on safety.