How Many Reps Should I Do?

Someone looked at one of my workouts the other day and said, “8 reps! Why reps? I always do 15?” I replied, “Why do you always do 15?” She didn’t know! The best I could make out from her answer was that she picked that number because she’d heard it somewhere and went with it. So, what is the difference in outcomes when using different rep ranges?

The three most popular desired outcomes of weight training are:
– Increased Strength
– Increased Muscle Size (Hypertrophy)
– Increased Muscular Endurance

In terms of the effect on these outcomes by the number of reps completed to failure (so you can’t do another rep), let’s start by looking at two extremes:

1 Rep Max = Pure power and strength
100 Rep Max = Pure muscular endurance

The other reps in between these numbers sit on a continuum between strength and endurance (see fig 1). So, what about another outcome – muscular hypertrophy (size)? Well, let’s rein in these rep ranges a little so that we’re dealing with the most common rep ranges that you see people doing in the gym.

1 Rep Max = Pure Power and Strength
5 Rep Max = Strength / Hypertrophy
10 Reps = Hypertrophy / Strength
15 Reps = Endurance / Hypertrophy

So, if your goal is mainly strength then work in the 1-8 rep ranges. If your goal is mainly hypertrophy then work in the 8-12 rep ranges. If your goal is mainly muscular endurance then work in the 15+ rep range.

Important: you need to adjust the load (weight) you are using so that whatever you’re doing is hard! If you’re doing 3 reps go HEAVY. If you’re doing 15 reps, go lighter. You should find it very difficult to complete the last rep on whatever set you’re doing!

In all of these recommendations I stress the word mainly! Vary what you’re doing occasionally – mix it up – chuck a curve ball in there now and again because your body gets used to what it does often so it needs new stimuli in order to facilitate change. If you’re regularly doing 3 sets of 15, chuck in a set of 7 (at an appropriately heavier weight) or do 1×14, 1×3, 1×15, 1×5, 1×33. Mix it up and have fun playing with your body!

So, what are the takeaway points from this?

1, Know what you’re trying to achieve.
2, Learn which method will be the best to achieve it.
3, Deviate from that occasionally to avoid plateaus.
4. The three main outcomes of weight training (muscular strength, muscular hypertrophy, muscular endurance) fall on an overlapping continuum so whichever rep range you choose will always have some spill-over benefits to the other outlying outcomes.

If you need some help to ensure that the four points above are covered as part of a progressive resistance training programme, designed by a fitness professional who knows how to achieve specific goals then check out our Personal Training Packages.

Dan Sroda

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