Those of us that do resistance training generally know that we should be doing 5 reps or less for strength, 6-12 reps for increasing muscle bulk, and 13 plus reps for endurance. And have you ever wondered what’s actually happening to your muscles while you are doing this?
It’s really simple, yet I’m continuously amazed at how many people who train with weights, or do other forms of resistance training, don’t understand the basic principle here.
And this, perhaps surprisingly, goes for a number of personal trainers too. A few months back I did a quick poll of some local personal trainers. I found only one out of the fifteen I polled could actually explain in any kind of simple terms what is happening – the rest just knew the rep-ranges.
To increase strength we are looking at getting as many motor units (a motoneuron and the muscle fibres it supplies) to fire as possible. In very basic terms this is getting as much of the muscle as possible engaged to move the resistance. We train this to happen by working with very heavy weights, with near failure occurring in the repetition range 1-5.
To increase the size of our muscles we work with near failure occurring in the repetition range 6-12. To increase the size of our muscles we are working to break down the muscle fibres so that the adaptation process can happen and they grow back larger.
To train for endurance we work with 13 plus repetitions. Here it is the number of times that the muscles can contract that is important.
So to summarize, for strength it’s about getting as much of the muscle to work as possible, for size it’s about breaking the muscle down and rebuilding it bigger, and for endurance it’s the number of times that muscle can contract.
Yet it’s surprising how many people doing resistance training don’t know these basics.