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Top 6 Training Mistakes That Are Costing You Muscle

After 37 years in gyms I think I can safely say I’ve seen it all. Every possible training mistake a person can make, and even a few I would never have thought of. There are some very common ones though. So common that I see them every day. If you’re doing any of these, you’re missing out on potential muscle growth. In addition, some of these mistakes will result in poorly sculpted muscle if you do gain.

Incomplete Range of Motion

man doing squats with proper form

This one will not only cost you muscle growth due to not working the muscle thoroughly, but it can result in shortened muscle bellies that quite simply look funny. A complete range of motion is necessary on any exercise to fully work the muscle. For example, when doing curls, lower the bar or dumbbell at the bottom of each rep until your arms are fully extended. Let them hang for half a second. Then lift, raising the weight smoothly to the very top of your range (without arching your back or moving your hips!). Repeat.

Squats done with proper form! A full range of motion while keeping the back straight. Not only will result in much better muscle development, good form also means a lower risk of injury.

Squats are another common exercise where you’ll see lots of people cheating on range of motion. I do half squats because at 53 my knees simply won’t tolerate a deep squat, but I’ll assume most of you reading this are considerably younger than I am. Unless you’re experiencing joint problems a full squat will have you dropping until your butt is almost on your heels.

Ballistic Motion

If you’re doing this you can forget about any significant muscle growth. A ballistic motion uses momentum, either from swinging the weight or using ‘body English’ to impart inertia to the weight, taking the strain off the muscle that you’re supposed to be working. I see this most commonly in curls, both with dumbbells and curling bars. In the case of dumbbells the weight is allowed to swing backward behind you at the bottom of the motion. The forward momentum as the weight swings forward carries it through most of the curling motion. In the case of a barbell or curling bar, the hips will move backward at the bottom of the curl, then thrust forward in combination with an arching of the back to ‘throw’ the weight up. In both cases, the biceps are hardly being worked at all.

Ballistic motions are usually the result of people trying to lift ‘heavy’, beyond what the muscle is actually capable of. It might feel good to curl 40 kilos, but you would be much better served by lowering the weight and using proper form.

Lack of Intensity

woman texting while sitting on machine in gym

Probably the most common mistake I see these days, especially since the advent of the mobile phone. Every single day I see people sitting on machines texting – not working out. First, if you’re working in a gym, that’s rude. Most of the equipment is in high demand. Don’t park on it. If you want to text or chat get off the machine so someone else can use it.

Aside from simple good manners, though, if you’re not training as hard as you can you’re cheating yourself of progress. A lot of progress! If you haven’t already, read the post on how your body builds muscle. Maximizing pump is the key and you won’t do that taking five minute breaks between each set.

I’m sure she’s having a great chat with her friend, but that’s not getting her the workout she needs. It’s also rude to park on machines, unless you’re in your own home gym.

In addition, unless you like hanging around the gym, increasing intensity will not only make your workout far more effective, it will also shorten your workout so you can get on to other stuff sooner.


Not as common as the others but equally bad for your progress. If you’re training the same muscle groups more often than every other day, you may be overdoing it. Your muscles won’t have time to recover and repair between workouts.

People most often make this mistake when first starting out and are riding the optimistic high of getting in shape. Unfortunately, they just end up tired, sore and frustrated at their lack of progress. Take it easy when first starting out. Focus on good form and finding the right weights that you can lift for 6 – 12 reps without cheating. The intensity will come as you get stronger.


Probably the one mistake most responsible for lack of progress. You need to be working out on a schedule. If you train a couple of days, then take five days off because you ‘just couldn’t fit a workout in’, then go back for a few days before taking another long break, don’t expect to make any progress. All you’re going to achieve is being constantly sore from workouts that your body isn’t in shape to do.

Set a schedule that has you working out at least 3 times a week, every other day and stick to it. It’s not about finding time. It’s about making time.

Improper Diet or Rest

fat man curling in gym

OK, I don’t ‘see’ this in the gym, but I can spot the people who either aren’t eating right or getting enough sleep. They’re the ones who train hard with good form but their body never changes. Trying to gain muscle? You need a healthy high calorie diet – for men in the range of four to five thousand calories per day. For women, 2500 to 3000. Wanting to lose fat? Find a TDEE (Total Daily Energy Expenditure) calculator and be sure you’re cutting your calories by 20% per day while still eating healthy.

Training hard and consistently but not getting results? The problem is almost certainly improper diet or lack of rest.

Not enough sleep will do it too. I have a friend who trains at 3 a.m. He goes to bed at 11:00. I ask him when he sleeps? He says that’s it – less than 4 hours per night. This same friend trains hard but complains that he never sees any progress. If you’re not getting proper rest your body won’t have chance to repair damaged muscle tissue and build new muscle.

Do It Right

You’ll never make good progress if you’re making any of the above mistakes. There’s no substitute for workouts done with intensity and proper form on a consistent schedule. It takes discipline and determination. There’s no easy path.

Check this previous post for more tips on how to train for maximum muscle growth.

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Will Dove

Will is a lifelong fitness nut. He started exercising religiously at the age of 16. Now 52, he still works out 5 times per week and maintains a body fat percentage in the single digits. Will is passionate about helping others to achieve their fitness and body image goals, and believes that most people fail to achieve these goals, not through a lack of self-discipline, but through a simple lack of knowledge.