To promote muscle growth, it goes without saying how important it is to use heavy weights during your workouts. In other words, the heavier you lift, the more stimulation you provide a muscle, and therefore the bigger and stronger you grow (if all the recovery points are taken care of). However, there comes a point that you must realize you are sacrificing optimum muscle growth for the sake of moving heavy weights.
Intensity can be defined as the percentage of your momentary muscular effort. The closer you can bring your intensity level to 100%, the greater the growth stimulation. This will require some pretty high levels of concentration and practice on your part since it is essential not to diminish the quality of your form to lift heavier. Heavy Weight + Perfect Form = GROWTH. This is something that I believe to be impossible to master, but the more you do to improve upon it, the faster you'll grow. Simply stated, go as heavy as possible without breaking your form.
If intensity is properly implemented, you can only train HARD, not HARD and LONG. This, however is a two sided scenario. Let's say you had a choice between curling a 170 lb barbell once, or a 130 lb barbell 6 times. Using the 130 lb barbell would be much more effective because each repetition will build on the previous when it comes to the level of muscular fatigue and muscle fiber damage. It is only on the final rep of a set that a person must exert 100% intensity, so using several reps with the 130 lb barbell will yield a greater level of fatigue and therefore a higher level of muscle stimulation than you would get from performing a single rep using the 170 lb barbell. Having said that, the final rep of a set is definitely the most important, so ensure that you apply 100% intensity to reap all of its benefits.
Six to twelve reps is the rep scheme I use, depending on the body part being worked. Large muscle groups receive the lower reps, while smaller muscle groups get higher reps. I find this works very well.
Your workouts must be intense, brief and somewhat infrequent to be effective. You must realize that individual recovery ability is a pre-determined genetic trait, therefore you must discover what works best for you through trial and lots of error. What works for one person doesn't always work for another. For me, I find that working each muscle group every seven days for no more than 60 minutes per workout works best. I cannot stress how important it is to use what works best for you. Some people can maybe work each muscle group twice a week, whereas others may only be able to work a muscle group once every two weeks. Another thing you should realize is that as you become bigger, your recovery tolerance will decrease. Be aware of potential signs of overtraining, but at the same time you don't want to be undertraining. As Mike Mentzer would say, "The question you should be asking yourself is not how much exercise do I need, but how little do I require?"
Now, let's analyze the true meaning of effective heavy training. Don't be one of those guys that goes to the gym to work chest, puts a shit-load of weight on the bar, but has his training partner upright rowing the weight for him. That's just as bad as having a low intensity workout when it comes to effectiveness. Secondly, it is of the utmost importance that you isolate the target muscle as much as possible. For example, when you are performing a set of incline dumbbell bench presses, rotate your shoulder blades back and flare your lats to stabilize the shoulder girdle. This will cause the shoulders to be lower than the pecs, and force the pecs to do more of the work, therefore isolating the pecs. Remember, it's bodybuilding, not powerlifting. The goal here is to use the most weight possible, while isolating the target muscle and then fully exhausting it.
Two general rules to adhere to while training heavy are:
1. You should be able to perform at least 6 reps on your own with the chosen weight, if not, then it is too heavy. Although this rule states that you should be able to complete 6 reps on your own, this may be somewhat broken during the final rep or two of the final set. If you choose to apply the forced reps intensity technique to your final set, go no lower than 4 reps on your own, then, with the help of a training partner, force out two to three more reps. All with perfect form of course, which leads us to the second rule.
2. You should be able to maintain perfect form through each rep of the entire set. No matter what you are doing in the gym, whether it be a straight set, forced reps, drop sets or negatives, it is essential to your success and injury prevention that you ALWAYS use perfect form. The last thing you need is an injury caused by your inflated ego.
Finally, let's take yet another look into the domain of intensity. Low intensity workouts won't do a thing to promote muscle hypertrophy and in my mind are a complete waste of time, effort and valuable calories. I'll try and give you an analogy to illustrate this point. Neither distance runners or swimmers show any great improvement in muscular size and strength from performing their respectable sports. This type of low intensity, repetitive exercise does very little to confuse or stimulate deep muscle fibers, both of which are essential to getting big. Therefore, it is almost a no-brainer that heavy, high intensity workouts are necessary to produce muscular hypertrophy. The heavier the weight and more confusion that you apply to a muscle (ie. Intensity), the greater number of deeper muscle fibers will be stimulated. As a final word, light weight, repetitive, low intensity workouts just don't cut it in this game.
Train Heavy, But Train Smart!