How heavy do I need to lift to build muscle?

If you’re anything like me, it’s not enough to just go into the gym and ‘do stuff’ in the hopes of packing on some extra muscle. It’s not enough to know just what you ought to be doing, either; you want to know why. If that sounds like you, this post is for you! If not, feel free to just read the parts in bold and the summary in red at the end, and just let me know if I can help with any part of it.


There’s a wide range of opinions on the Internet pertaining to how you should and should not go about adding muscle, whether it’s for those of us who want to look ‘athletically toned’ or those of us (hi guys!) who want to be mistaken for Thor/She-Hulk by a casual onlooker.

‘Just do heavy singles!’
‘Just do volume work!’
‘Max out every day!’
‘Never max out at all!’
‘Pink dumbbells! Barbells! Kettlebells! Bodyweight!’


So who’s right? Well, everybody is. Sort of.

First, let’s look at this study by Schoenfeld et al. Two groups participated in one of two volume-equated programs (meaning that the overall workload was the same) in which they either did sets of 3-rep-maxes (3RM) or 10-rep-maxes in a particular lift. At the end of the study, both groups gained muscle size, but there was no significant difference between the two. This means that:

For hypertrophy (muscle growth) the rep range you use does not seem to matter – your overall workload, or volume, does.

That being said, there are some obvious downsides to using heavy triples, doubles or singles all the time – it beats you up, physically and mentally, and it takes a lot longer to build volume than with moderate rep ranges. There might not be anything magic about the ‘sets of 10’ rep range commonly used to gain muscle, but it is a convenient way to accumulate volume (aka overall work done or ‘sets x reps x weight’) without getting wiped out and overly fatigued – or injured – for the next session.

If you clicked on the study link back there, you may have noticed that the 3RM group gained more strength than the 10RM group. This is because strength is usually defined as something close to a 1RM attempt, and as training adaptations are largely specific to the type of training you do (ie, you get better at the rep ranges you train in) it makes sense that the group who trained with heavier weights would get better at lifting heavier weights, though this had no significant effect on muscle size. Remember there are many other factors involved in strength gain besides muscle growth.

Okay, so sets of 10 are an easier way to accumulate volume and thus get more muscle without being beat up. Is there any benefit at all to using heavier sets? And what about lighter sets? Can’t we get in even more volume with sets of 20, or 30?

With regards to heavier sets, there is some evidence that varying your rep ranges can result in better gains than just sticking to one (see Dr Mike Zourdos and his work on daily undulating periodisation, or DUP), so there is likely some benefit from using heavier loads for part of your training even if your only concern is muscle or aesthetics, and not strength. After all, stronger muscles move more weight, which means more volume and thus more hypertrophy.

So what about lighter weights? Are the fluorescent dumbbell crowd doing the right thing?

As it turns out, there does seem to be a minimum ‘heaviness’ threshold relative to your current strength levels that you need to be above to get results. This is obvious when you think about it – as Eric Helms points out, you can curl a pencil for hundreds of reps but you’re unlikely to make your biceps grow. Exactly where this point is has not been discovered, and new techniques such as BFR (blood flow restriction, which allows for similar results from light weights as you might get from a heavier load) are further complicating the issue, but we do have a good idea about where the point of diminishing returns might be.

In this study by Schoenfeld et al, one group of trainees worked in an 8-12 rep range while the second group worked in a 25-35 rep range. Both groups achieved similar results in terms of muscle gain, but the higher rep range group had to perform more total volume to get the same result. They also reported more instances of acute pain and even vomiting during training, which is not usually a good time. This means:

You will likely be working harder and longer for the same results if you use more reps per set than somewhere between 12-15 as a rough maximum.

So what about training to failure? Shouldn’t we break our figurative backs each and every set to get the best result possible?

Probably not. Remember that training volume is the most important factor in muscle gain; try taking a set of your favorite exercise to absolute muscular failure. Rest 3 minutes, and try again – if you get even 2/3 as many reps, give yourself a medal! Going to failure has benefits in terms of muscle fiber recruitment, but it’s too damaging to overall volume (and thus results) to be used all the time, and can wear you out for the rest of your workouts that week as well. Thus, for the most part, it’s wise to keep 1-3 reps ‘in the tank’.

So, to sum up:


1. Rep ranges don’t play a major role, as long as you don’t go too light – 8-15 is likely a solid range to stick to and thus avoid preventable injuries, excessive fatigue, and doing more work for less results.

2.Volume (overall workload) seems to be the single most important factor in muscle growth, and is probably best thought of as ‘sets x reps x weight’. Warm-ups are likely too light to be counted for most people (elite powerlifters are another story!).

3.Going to failure has benefits but is damaging to overall volume and therefore damaging to results. Use it sparingly, and keep a rep or two in the tank.

4.A final point worth making: for the most part resistance is resistance, in the sense that your body doesn’t care if you’re moving a kettlebell, a dumbbell, or just your own body against gravity. Use whichever tools you prefer and are appropriate for your physical condition.


How much volume is too much, and how often to train, would make this an even longer post. I’ll write about that another time. If you enjoyed this post or found it helpful, let me know!

Disclaimer: I am not a scientist or a researcher. The scientists and researchers I have quoted above are also bodybuilders and powerlifters as well as being individuals whose opinion and integrity I trust, along with being valued and respected by other above-board individuals in their field. In short: they know their stuff, and you can trust them.

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