Many may think they are training near muscle failure, but in reality, they are training with quite a few repetitions before that point of failure, even with 6 RIR. Research shows this.
TRAINING WITH RIR
To build muscle mass, you must train your sets close to muscle failure, that is, to the point where you can no longer perform a full repetition. If you take enough time for your training, you don’t need to train completely to the limit: it suffices to keep two to three repetitions ‘in the tank,’ or to train with 2-3 reps in reserve (RIR). This way, you can handle more volume and therefore achieve muscle growth faster.
RESEARCH
But how does that work: does the average gym-goer actually train with 2-3 RIR?
Researchers asked a group of 160 strength athletes who regularly bench pressed for muscle growth: what weight do you normally lift for 10 repetitions when bench pressing with free weights? Next, they had them repeat that weight, but with an imaginary gun to their head: how many reps can you *actually* do?
When they went to muscle failure, only 4% of them could do 10 repetitions. When it comes down to it, the rest can complete significantly more repetitions: about a third could do 13-15 repetitions, and 14% could even do more than 20!
BEGINNERS VERSUS ADVANCED
Apparently, many strength athletes do not train hard enough to achieve optimal results regarding muscle growth. However, we must make a distinction here between beginners and advanced athletes.
Beginners can achieve good results with minimal effort, simply because the training stimuli are completely new to the body. Muscle gains can be achieved even with 6 RIR, albeit more slowly than with 2-3 RIR.
The more advanced you become, the more training stimuli your muscles need to grow. Completing your sets with 6 RIR is then no longer sufficient.
ADVICE
First, determine the relative intensity at which you want to train, i.e., how many RIR. 2-3 RIR is a good starting point for average strength athletes. If you cannot train often, and therefore do less volume, train even closer to muscle failure, possibly to complete failure.
Check your effort occasionally by pushing yourself to muscle failure. Maybe those 2 RIR were actually 5 RIR.