If your primary goal is bigger muscles and you’re not making regular gains in strength and size you’re probably making one or more of the following common training mistakes. These are some of the biggest mistakes a bodybuilder can make, and correcting them can often make the difference between outstanding gains and none at all:

1. Not Training Hard Enough

To stimulate muscular strength and size increases you have to work your muscles harder than they are accustomed to, and the harder the better.

Specifically, you should perform each exercise until it is impossible to continue in good form, using a heavy enough weight that you are only able to perform between 3 and 12 slow, controlled reps (The slower the reps, the fewer you need to do. By slow I mean taking at least five seconds to lift and five seconds to lower the weight, but even slower is better; I recommend taking ten seconds to both lift and lower the weight.)

The exercise is not over when the muscles start to burn or when things start to become uncomfortable. The real valuable work is just starting. The exercise isn’t even over when your muscles feel like they’re on fire and your heart is pounding through your chest, you’re just getting to the best part. The greatest stimulus for muscular strength and size increases occur during the last few hardest reps, and if you give up at any point short of an all-out effort, you aren’t going to get nearly the same growth stimulation.

2. Not Training Progressively

As you become stronger you must attempt to lift progressively heavier weights to stimulate further improvement. If you continue to use the same weights on all your exercises despite increasing in strength, the weights will no longer be challenging enough to stimulate further improvements. Assuming you are using very strict form, attempt to either perform more repetitions or use a slightly heavier weight on every exercise, every time you train.

3. Doing Too Many Exercises and Sets

It is the intensity of muscular work that stimulates strength and size increases, not the volume. Doing any more exercise than minimally necessary will reduce rather than improve gains, by interfering with the process of recovery and adaptation.

In most cases, all you need is one hard set of only one or two exercises per major muscle group. More is rarely necessary, and usually counterproductive.

4. Training Too Frequently

The body must be allowed adequate time between workouts to fully recover and adapt, or gains will not occur. Exercise does not produce any improvements in the body, exercise can only stimulate the body to produce the improvements, if it is intense enough, or prevent the improvements from being produced, if it too much is performed, too often. The body produces the muscular strength and size increases stimulated by exercise, but only if it allowed adequate time between workouts to do so.

5. Not Keeping A Workout Journal or Progress Charts

Proper adjustment of training volume and frequency to avoid overtraining requires objective evaluation of progress. If you’re not keeping accurate records of your workouts, you can not objectively evaluate the effectiveness of your program and make the necessary changes to keep gaining or get your progress back on track.

6. Using Sloppy Form

Poor form reduces the effectiveness of an exercise and increases the likelihood of injury. While an entire book could be written on the specifics of proper exercise form, one of the most effective ways to improve exercise form in general can be summed up in two words: slow down. Moving more slowly makes it easier to maintain proper positioning and alignment, and allows for better focus on performing the exercise correctly and on intensely contracting the target muscles.

7. Switching Exercises or Routines Too Frequently

Real gains are made by consistent progress on the basic exercises over time. Changing routines too frequently prevents the body from getting past the initial, primarily neural/skill adaptation stage and into the more productive training that follows.

The belief that one must change their routines regularly to avoid plateaus because the muscles become resistant to further improvement with specific exercises is based on the observation that the fastest improvements in performance on an exercise routine occur over the first six to eight weeks after which it begins to slow down, and that changing the routine appears to solve this problem.

During the first several weeks performing a new exercise or routine a larger percentage of the improvements in exercise performance are due to neural or skill adaptations. After this initial period of neural adaptation, performance improvements slow down and the majority of adaptation is occurring in the muscles. This is where the real progress starts, however, and it is important to not change the routine at this point. It will be slower than during the initial six to eight weeks, but you will make progress if you properly adjust your workout volume and frequency.

Contrary to bodybuilding myth and uninformed opinion, the muscles do not stop adapting to a particular exercise, method, or routine – if there is sufficient overload a muscle will be stimulated to grow, and as long as volume and frequency are not excessive, and adequate rest and nutrition are provided, and one hasn’t already reached the limits of their potential, it will grow stronger and larger.

If you only performed a few, basic barbell exercises, covering all the major muscle groups, and trained hard and progressively you would eventually become as big and as muscular as your genetics allow. There is no need to constantly switch up angles, rep methods, or anything else.

8. Not Training Legs

Heavy leg work,  squats, deadlifts, leg presses, etc., can be brutal when done properly, and as a result many would-be bodybuilders avoid it, preferring to focus on the relatively easier upper body exercises. This is a huge mistake, as heavy leg work appears to have a beneficial effect on growth throughout the entire body, particularly squats and deadlifts.

Do not skip training legs. Doing so robs you of potential full-body size increases, and having a well developed upper body and chicken legs looks stupid.

9. Not Eating Enough Quality Food

Your body requires both material and energy to produce new muscle tissue. Often, when skinny guys complain they have a hard time gaining muscle mass, it turns out they simply aren’t eating enough food in general or protein in particular to support the growth they stimulate during their workouts. If you want to get big, you have to eat big. This doesn’t mean pigging out, but getting enough quality food and protein daily to add at least a few pounds per month, but not so much your waist size or abdominal skinfold increases significantly.

Just like your workouts, you have to keep track of your eating and make adjustments based on how your body responds.

10. Wasting Money on Bogus Bodybuilding Supplements

While stopping wasting your money on supplements might not make your muscles suddenly start growing, it will stop your wallet from shrinking.

There are a few supplements which have proven to be beneficial, but most provide little or no benefit. If you want to know which supplements work and which don’t, don’t read about them in the bodybuilding magazines – they make a large amount of their money selling advertising to supplement companies and are hardly unbiased sources of information on the subject. Almost everything you read in muscle magazines is bullshit. If you want reliable information on supplements or their ingredients, read the scientific journals, and even then, do so critically.