While it’s important to think positive and focus on all the things you should be doing to achieve your 
goals, it’s equally important that we focus on those things that interfere with our goals and remind ourselves to avoid doing them. Some call it the “not to do list,” which I like. Many of the behaviors on not-to-do lists are deal breakers, so it’s arguably more crucial that we identify and curtail those that apply to our lives. But that’s hard; these are behaviors we might already be doing. Heck, they might be bad habits we’ve developed, or biases we’ve internalized. And so before adopting good behaviors, we should clear out the bad ones. Otherwise, we’re just pissing in the wind.
What are some things you shouldn’t be doing if your ultimate goal is to build muscle?
1. Skip sleep for a late (or really early) training session.
It feels good to make that late night Facebook post about the weights you just lifted, or brag about your 4:30 AM wakeup for CrossFit class. It looks impressive. That’s true dedication, right? Except that you’re not building muscle in real time as you hoist that bar off the floor. You build muscle by recovering from your training session, andsleep is where we do most of our recovery. Sleep is where everything good happens. Sleep debt actively inhibits muscle recovery and hypertrophy and 
promotes muscle degradation. Sleep deprivation increases cortisol and reduces testosterone; for optimal muscle building, the former should be lower and the latter higher. One older study found that total sleep deprivation increased urinary excretion of nitrogen, which could be indicative of muscle breakdown and loss of lean mass.
Sleep is (almost) everything.
2. Sacrifice form just to increase weight.
For two reasons. First, poor form will inevitably lead to injury on a long enough timeline, which means you won’t be lifting at all and your muscles won’t be receiving any stimulus. Second, poor form is a shortcut, often curtailing your range of motion and limiting the amount of work your muscles are doing. If it’s easier, you’re not actually exposing your muscles to the work they need — and you think you’re giving — to get stronger. You’ll still gain muscle with bad form, but it won’t be as effective as the weight would indicate and you’ll eventually hurt yourself.
A perfect example of this is the perceived dichotomy between the front squat and the back squat. Although back squats allow you to lift more weight, they’re often harder to do right, and a recent study suggests that doing the front squat, which many find to be a more intuitive lift, with a lower weight can be just as anabolic as doing a back squat with a higher weight.
3. Speed through the eccentric phase (drop the weight).
Everyone focuses on the concentric phase of a lift. The lifting off the bar off the floor in the deadlift. The press upward during the bench and overhead presses. Even the generic term — “lift” — implies the primacy of the concentric phase.
But there’s evidence that the eccentric phase is just as important for hypertrophy and strength gains. A 2014 study showed that training emphasizing the eccentric phase resulted in extremely high post-workout biomarkers of muscle anabolism. This didn’t show actual muscle gain, but that’s because it was a one-shot look at the acute effects of eccentric training. And a 2009 review determined that high-intensity eccentric training can increase muscle mass to a greater degree than concentric training.
You don’t necessarily have to lower the weight as slowly as possible, but lower it with control. Don’t let gravity do the work for you. Resist it.
4. Stick to the ideal routine even if it’s not working.
You’re doing everything everyone says to do. You’re squatting and pressing three times a week, deadlifting once, and learning how to power clean. You’ve got a dog-eared copy of Starting Strength by your bedside. A permacloud of weightlifting chalk dust follows you around like PigPen. For most people, this kind of dedication builds muscle. Barbell training works wonders for most people, provided they do it with the right form and intensity. It allows you to handle the most weight and places dynamic stresses on your musculoskeletal system. But don’t get caught up in barbell dogma if it simply isn’t producing the results you want. 3×5 squats, deadlifts, and presses aren’t the only way, no matter how loudly Internet commenters scream it.
Many people find that higher-volume training in the 8-12 rep range offers a good balance between volume and intensity and produces greater hypertrophy with real strength.
5. Try to lose weight.
I’m not suggesting it’s impossible to lose body fat and build muscle at the same time. Lifting heavy is probably one of the best things you can do to lose body fat and improve body composition. It’s certainly doable, if a bit more difficult than focusing on either alone. But when your primary goal is gaining muscle, losing weight is really, really hard. For one, muscle weighs more than fat, so if you’re successful at gaining muscle you will likely gain weight. Two, gaining muscle requires caloric excess, which makes losing weight is really hard if not downright impossible.
So if you’re successful at losing weight, you won’t gain much muscle. If you’re successful at gaining muscle, you won’t lose weight. The two are not compatible.
6. Train for endurance.
Large muscles aren’t just energetically and kinetically costly for endurance athletes; they’re really difficult to develop on the training schedule required for serious endurance work. The training needed to get really good at endurance work crowds out any chance you’ll have to train the weights. There simply isn’t enough time in the day or week to train for and recover from both muscle hypertrophy and elite endurance performance. And yes, endurance athletes are increasingly integrating strength training into their regimens, but not to bulk up. They’re lifting weights to improve their sport, become more resistant to injury and wear and tear, strengthen their connective tissue, and get stronger overall.
7. Spend hours in the gym doing every exercise.
Building muscle requires dedication, consistency, and getting in there and doing the work even when you don’t really feel like it. But that doesn’t mean you have to spend three hours killing yourself in the gym. You don’t have to hit every muscle group with five different exercises. You don’t have to do donkey calf raises. You don’t have to do pull-ups, chin-ups, and lat pulldowns. In fact, trying to do too much can cause overtraining, which is counterproductive to actually gaining the muscle.
If every training session is an hours-long affair, you’ll start making excuses not to train that day. Before long, you’ll be skipping entire weeks and wondering why you never feel like lifting. You’ve set the bar too high to stick to the routine. Very few people can consistently train for three hours a day without hating their lives. You’re probably not among them.
8. Ignore other forms of physical activity.
If you want to gain muscle then, yes, your focus will need to be strength training. But I caution against strength training to the exclusion of everything else. I don’t have much hard science backing me up here. It’s more of an intuition borne out of years of seeing people fail and succeed. But it’s the folks who do things other than strength train that often have the best physiques. They’re playingfrisbee or paddle boarding. They’re hiking and sprinting and slacklining. They’re challenging their bodies (and minds and muscles) in different ways. They’re taking time out of their lives to have fun and simply enjoy the body they’re diligently creating in the gym. Everything in life must have balance; I have yet to see a counter example. Have you?
9. Do high-rep conditioning workouts like P90x.
If you just want to lean out and build stamina and the capacity to withstand great physical discomfort, programs like P90x work well. These are high-rep, low-weight workouts that never seem to end. You’ll do things like air squats into pushups into light dumbbell presses into reverse lunges into tuck jumps, with very little rest. If you ever go down to the local park, you might see hordes of people doing “boot camp” workouts that look very similar. And all these will make you tired and sore the next day, and you’ll get “fitter” and better conditioned. But to build muscle? To gain lean mass? These are not the programs you want to be doing.
10. Do post-workout cold water plunges.
Cold water plunges can help restore performance and reduce recovery times in hard-charging athletes and professional sports teams are beginning to install ice baths in their facilities to take advantage of this. But emerging evidence suggests this may come at a cost: reduced strength and muscle gains. In one recent paper, researchers separated athletes into two 12-week resistance training groups. One group sat in cold water for 10 minutes after training. One group practiced active recovery for 10 minutes. After 12 weeks, the active recovery group enjoyed greater strength and mass gains than the cold immersion group. For the second phase of the study, they measured acute changes in anabolic biomarkers and found that cold water immersion blunted post-workout activation of key proteins in muscle cells for up to two days.
Cold plunges are still useful for trainees. If you need to recover quickly from a game of Ultimate, or you’ve got another event coming up in the CrossFit games, or you’re on a ski trip and intend to make the most of every single day, dunking your body into cold water after a session can help you reach your goals. If you’re an endurance athlete, cold water plunges appear to be beneficial (PDF). If you’re competing, it will probably help you recover. And I’ve had great success using alternating cold/hot plunges at night to improve my sleep. But if your goal is to gain muscle above all else, post-workout cold water plunges may interfere and should be delayed to rest days.
These are probably the most common mistakes I see people making when trying to build muscle, but there are definitely others I’ve left out. What mistakes have you made – or are still making — in your quest to gain lean muscle mass?
Thanks for reading, all. Take care!