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If you're new to working out, you've probably heard people talk about using "proper form" or "good technique" when lifting weights. But what does that actually mean? And more importantly—does it really matter for building muscle?
A narrative review (a type of research paper that summarizes and analyzes all the existing scientific studies on a topic) published in 2024 titled "Optimizing resistance training technique to maximize muscle hypertrophy: A narrative review" by exercise scientists at CUNY Lehman College (including popular fitness educator Jeff Nippard and renowned muscle growth researcher Brad Schoenfeld) looked at all the available studies on workout technique to answer a simple question: What's the best way to perform exercises if your goal is to build muscle?
The good news? Building muscle might be more flexible than you think. You don't need to be a perfectionist about every little detail. But there are a few key things that really do seem to matter.
The researchers reviewed dozens of studies on different aspects of exercise technique including things like how fast you should lift, how far you should move the weight, and how strict your form needs to be. Here's a summary of what they discovered from their selected studies:
One of the clearest findings from the research is about range of motion (ROM)—basically, how far you move the weight during an exercise. It turns out that training with a full range of motion, especially when your muscles are stretched, is one of the most important factors for building muscle.
For example, if you're doing a bicep curl, lowering the weight all the way down (where your bicep is fully stretched) appears to be better for muscle growth than only going halfway. The research showed that exercises performed at longer muscle lengths (when the muscle is stretched) led to better muscle growth than exercises performed at shorter muscle lengths (when the muscle is squeezed).
Think of it like this: when you stretch a rubber band before letting it snap back, you're using its full potential. Your muscles work similarly—they grow better when you work them through their full range, especially in that stretched position.
Tempo refers to how fast or slow you perform each repetition. Some trainers will tell you to lift super slowly (like taking 10 seconds per rep), while others say to go fast. So what does the science say based on this review?
The research found that repetitions lasting between 2 and 8 seconds total work well for building muscle. This gives you a lot of flexibility. You could do a 1-second lift and a 2-second lower (3 seconds total), or a 4-second lift and 4-second lower (8 seconds total)—both would fit within the guidelines as possible examples.
What matters most is that you're controlling the weight, especially when you're lowering it. Don't just let gravity do the work. Your muscles should be doing the work of actively lowering the weight in a controlled way, not just dropping it or rushing through the lowering phase. For nuance, an exception would be something like Olympic lifts where the weight is often dropped from overhead with bumper plates for safety purposes, but these aren’t often used for muscle growth.
The researchers couldn't find strong evidence that super-slow reps (like 10+ seconds) are better for muscle growth. In fact, some studies suggest that going too slow might actually be worse but the mechanism was unclear. The sweet spot seems to be that 2-8 second range—fast enough to keep your workout efficient, but slow enough to maintain control.
Here's where things get interesting. A lot of gym advice focuses on very specific details—exactly where to place your feet, precisely how wide your grip should be, keeping your body perfectly still, and so on.
But here's the truth: there's actually very little research directly testing whether these small technique details matter for muscle growth. Most exercise guidelines are based on biomechanics and injury prevention, not on studies that actually measured muscle growth.
The one exception based on the studies reviewed? Foot position during calf raises. One study found that pointing your toes in different directions (inward, outward, or straight) did affect which parts of your calf muscles grew more. But for most exercises, we simply don't have research showing that small form adjustments significantly impact muscle growth.
You've probably seen people at the gym doing exercises two different ways:
Surprisingly, we don't have good research comparing these approaches for muscle building. Theoretically, using strict form might target your intended muscle better. But it's also possible that using a little momentum to lift heavier weight could still build muscle effectively. We just don't know for sure yet.
The researchers suggest minimizing extra body movement when possible, but they acknowledge that this recommendation is based more on theory than proven facts. More research is needed on this topic.
The researchers concluded that building muscle is more forgiving than many people think. You don't need to stress about every tiny detail of your form. Instead, focus on the two big things that clearly matter:
Beyond that, follow standard exercise instructions for safety and effectiveness, but don't overthink it. Your individual body proportions (height, arm length, leg length, etc.) might require some natural adjustments to what "perfect form" looks like anyway.
Start with a full range of motion on every exercise. Whether you're doing squats, bicep curls, or chest presses, make sure you're moving through the complete motion—especially lowering all the way down to where your muscles are slightly stretched but you still have control and position to start another rep.
Count to control your tempo. A simple approach: take about 1-2 seconds to lift the weight, and 2-3 seconds to lower it. You don't need to be exact—just make sure you're not rushing or letting gravity do the work. If you're new to lifting, start on the slower side (like 2 seconds up, 3 seconds down) to build consistent movement quality.
Focus on the stretch position. Pay extra attention to the bottom portion of exercises where your muscles are stretched. For example, on a Romanian deadlift, the stretch happens when you're hips are hinged back with the weight somewhere around the middle of your shin (this position under load really lights up the hamstrings). On a chest fly, it's when your arms are out wide. The dumbbell chest fly can give you a great stretch, but this is a good time to point out that you still want to be in a strong position for the next rep. If you go too far, you’ll be out of position and it’ll be a mechanically weak position and stress your shoulders. In general, these slightly stretched positions near the end range of motion seem to be particularly important for muscle growth, so don't skip them or rush through them.
Don't worry about perfect form—worry about safe form. As long as you're not doing anything that hurts or feels risky for injury, small variations in your technique are probably fine. Your unique body proportions mean your squat might look a little different from someone else's squat, and that's okay. The key is moving safely through a full range of motion with control. We have an article about this (click here). A good rule of thumb is to have someone like a personal trainer do a movement assessment on you so that you can determine if your nuances in movement are related to your body type or a compensation that you should address. Additionally, we have an article about assessments if you want some that you can do on your own (click here)
Experiment within the guidelines. Since the research shows that various tempos work (as long as they're in that 2-8 second range), feel free to try different speeds and see what feels best for you. Some people like slower, more controlled reps. Others prefer a bit faster. Both can work for building muscle as long as you're maintaining control and using a full range of motion.
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Concentric phase — The lifting portion of an exercise when your muscle shortens (like curling a weight up during a bicep curl).
Eccentric phase — The lowering portion of an exercise when your muscle lengthens while under tension (like lowering a weight down during a bicep curl). Often called the "negative."
Hypertrophy — The scientific term for muscle growth. When your muscle fibers increase in size, that's hypertrophy.
Muscle length — How stretched or shortened a muscle is during an exercise. "Long muscle length" means the muscle is stretched; "short muscle length" means the muscle is contracted/squeezed.
Narrative review — A type of research paper that summarizes and analyzes all the existing scientific studies on a particular topic to identify patterns, draw conclusions, and provide recommendations based on the collective evidence.
Partial ROM — When you only move through part of the full range of motion in an exercise (like doing half squats instead of full squats).
Range of motion (ROM) — The full movement distance of an exercise from start to finish. A "full ROM" means moving through the complete natural range of the joint and muscle.
Repetition (rep) — One complete cycle of an exercise, including both the lifting and lowering phases.
Repetition tempo — How fast or slow you perform each rep, usually measured in seconds. Often written as numbers like "2-0-3" (2 seconds lifting, 0 seconds pause, 3 seconds lowering).
Resistance training (RT) — Any form of exercise where you work your muscles against a force or weight—this includes lifting weights, using resistance bands, or even bodyweight exercises like push-ups.
Set — A group of repetitions performed consecutively without rest. For example, "3 sets of 10 reps" means you do 10 repetitions, rest, then repeat that two more times.
Strict form — Performing an exercise with minimal involvement of muscles other than the intended target muscles, keeping the body stable and controlled throughout.
Target muscle — The specific muscle or muscle group that an exercise is designed to work. For example, the biceps are the target muscle in a bicep curl.
Androulakis Korakakis, P., Wolf, M., Coleman, M., Burke, R., Pinero, A., Nippard, J., & Schoenfeld, B. J. (2024). Optimizing resistance training technique to maximize muscle hypertrophy: A narrative review. Sports Medicine, 54(3), 835-851. https://doi.org/10.1007/s40279-023-01981-7
