An age-old question of bodybuilders is whether or not to take each set to “failure.” By failure I mean momentary muscular failure. This is when the weight stops concentric movement. Simply put, failure is when you can no longer lift the weight.
If you go into most gyms that still allow lifters to do their thing, you will see nine out of 10 guys and gals straining mightily as they take each set to failure. Some think that this is the only way to build muscle. The thinking is that most of the reps you do up until muscle failure are pretty much worthless; it’s only the last two or three that trigger growth. It all comes down to fiber recruitment, they say. If you don’t train to failure, some fibers never get called in to help and those fibers will then not be stimulated to grow. There isn’t time or space to address all of the questionable thinking in that statement, but at least you get the picture. Yet others do the same thing but for a different reason. Each and every workout for them is a test of their mettle; a gut check, if you will. Anxious for rapid progress, they test themselves on every set of every exercise, desperately trying to experience greater strength than the previous workout. Normally these are younger guys who have yet to realize that miracles don’t happen overnight. If you are familiar with any of my writing, you will already know where I stand on the issue; nevertheless, I am always open to new data and the implications they might have on training strategies for growth. One new study just happens to add quite a lot to the conversation.
Researchers in Denmark recently published a study looking at recruitment patterns in the deltoids during lateral raises. Before I go further, let me say there are a few shortcomings to this study, but I still think the insights it provides are worth noting. This study compared heavy loading (3 reps) versus lifting to failure and used electromyography (EMG) activity to determine fiber recruitment. I should note that the subjects were untrained and the resistance apparatus was elastic tubing. Now, before you write this off as irrelevant, hear me out.
What they found was that EMG activity was actually higher at the midway point for the lighter resistance than it was for the 3rd rep of the heavy set. But this isn’t the important part. They also found that EMG was maxed out before reaching failure. That’s right, they found that EMG activity and hence muscle fiber activity was higher during reps 10–12 than it was at failure using a 15-rep load. The take-away message from this study, despite its subject pool or use of elastic bands, was that muscle fiber recruitment plateaued 5 reps before failure. So, put this little tidbit of information in your toolbox and use it the next time you’re planning your training strategy. It may just allow you to train but not overtrain.
Reference: Sundstrup E, et al, “Muscle Activation Strategies During Strength Training with Heavy Loading vs. Repetitions to Failure,” J Strength Cond Res. 26(7):1897-903; July 2012