The Truth About Muscle Burn: What Really Builds Muscle
Why Feeling the Burn Isn’t The Best Way to Measure Progress
You’re mid-workout. Your legs are shaking, your glutes are on fire, and you swear you can’t possibly do another lunge. When you take a step, your legs feel like spaghetti. This workout has been killer and you're definitely feeling the burn.
But have you ever stopped to wonder if feeling the burn actually means your workout is effective? If you're sore for days after leg day, does that mean you’re really building strength or triggering muscle growth?
It might surprise you to hear this, but that burn you feel isn’t always a sign that your workout is working. Muscle soreness and fatigue are just part of the picture when it comes to hypertrophy (aka muscle growth). So what does lead to muscle growth? How do you actually get stronger and build muscle?
Feeling the Burn- What’s Really Going On?
So, when you’re having a really good leg day and you start to feel that burn, or you're doing bicep curls and your arms are on fire, you’re probably thinking: this has to mean my muscles are growing. Right?!
Time for a little science (don’t worry, it’s the fun kind). That burning sensation happens when your muscles have an excess of hydrogen ions (H⁺), which build up during intense effort. This causes a drop in muscle pH, making your muscles feel acidic and leading to that familiar burn feeling. For a long time, people thought that lactic acid buildup caused this feeling, but that has been proven to be a myth. Lactate actually helps by transporting those hydrogen ions out of your muscles, so that your body experiences less fatigue. [1]
That burning feeling is part of what scientists call metabolic stress, which happens when your muscles work hard and energy demand is high. Metabolic stress contributes to muscle fatigue, which is your muscles getting tired and less able to contract.
So, yes, feeling the burn means your body is working hard, but it doesn’t necessarily mean your muscles are growing. You can absolutely build strength and size without feeling the burn!
What Actually Builds Muscle and Strength?
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So, how do you actually build muscle? If “feeling the burn” isn’t the secret, what is?
Just because you don’t feel that intense burn doesn’t mean your workout isn’t effective. You still need to challenge your muscles consistently in order for them to grow.
When you lift weights, your muscles experience tiny micro-tears. It might sound a little intense, but this is a good thing. During recovery, your body repairs those muscle fibers and makes them grow bigger. This is what leads to muscle growth, also known as hypertrophy.
If you want to grow your muscles, then you must progressively overload your muscles. Progressive overload means that you have to gradually increase the demand placed on your muscles so that you can keep seeing progress over time. The National Academy of Sports Medicine describes progressive overload this way:
“Three mechanisms of building muscle through strength hypertrophy are metabolic damage, muscle tension (force), and exercise-induced muscle damage. With respect to progressive overloading, you are effectively attacking the muscle-tension variable by increasing the load and causing an adaptation in force output of the muscle over time.” [2]
In layman's terms, you want to increase things like time, weight, or intensity as your body adapts. For example, if a certain weight starts to feel easy, it may be time to add more reps, slow the tempo, or go up in weight to keep your muscles challenged.
You don’t have to always be sore after a workout or feel like your muscles are burning in order to grow your muscles. Be consistent with your workout routine and progressively overload your muscles- you will see progress!
Full Range of Motion is Better Than Feeling Your Muscles Burn
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Now you know that progressive overload is one of the keys to growing your muscles. But something that is less talked about is using your full Range of Motion (ROM) when you are lifting weights.
You’ve probably seen fitness influencers say that you need to “feel the reps” to have muscle gains. But, to be honest, your ROM matters more than feeling your muscles burn.
Range of motion means moving your joints through their full and natural range, in a safe manner. Keep in mind that you need to be safe- do not force your joints past their natural limit. If it feels painful or uncomfortable, then make sure you are not hyperextending because you can injure yourself.
For example, if you are doing bicep curls, make sure you fully extend your arm at the bottom of the movement. Short pulses, when you're curling, would make you feel the burn, but you rob yourself of fully utilizing your muscles. You’d miss out on a complete stretch of the muscles, a stronger contraction, and more time for your muscles to be under tension.
Research backs this up. A study in the Journal of Strength and Conditioning Research found that training with a full range of motion led to greater muscle growth and strength gains than partial reps, even when the shorter reps felt harder. [3]
So if you’ve been doing movements that specifically make you feel the burn, try using your full range of motion. Control your movement and challenge your muscles.
New Exercises Might Feel Harder, But That Doesn’t Mean They’re Better
Have you ever tried a new exercise and felt the burn immediately? Or maybe you were sore and shaky afterward. You probably thought that the burn, soreness, and shakiness, meant the exercises were working. Maybe, you also no longer get very sore after you do some of your old workouts that you have done a million times.
But, just because you feel sore the next day after you try a new exercise doesn’t mean that it is more effective.
When you try a new exercise, your body is trying to figure out the new movement. However, as previously mentioned, progressive overload is key to hypertrophy. If you are no longer feeling challenged by the exercises that you are doing at the gym, you don’t need to switch to a different exercise.
Instead, you may need to add more weight, increase the number of reps, or slow down your movement. If you want your muscles to grow, you need to be able to track the exercises you are doing. It will be extremely difficult to keep track of your weights and reps if you are constantly switching exercises and trying new workout routines.
Consistency is what drives results. In fact, many of my clients make the most progress when they stick with a handful of exercises and build habits and consistency in their routines. You don’t need to do something completely different every time you work out. What you do need is a way to track your lifts, reps, and progress- this is how you will consistently be able to challenge yourself.
Takeaway: Build Muscle With a Solid Routine
Photo by Anastasia Shuraeva
Feeling the burn might feel like the best thing to do in the moment, but it’s not the best way to measure your progress. Soreness, shakiness, and muscle fatigue can happen for a lot of reasons, especially when movements are new. But if your goal is to build muscle and get stronger, then what really matters is consistency, proper form, full range of motion, and gradually increasing the challenge.
You don’t need to switch up your routine every week. The most effective progress happens when you create a routine and stick with it. Make sure, over time, that you’re lifting a little more weight, controlling your movements, and sticking to a plan that you can be consistent with over a long period of time.
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