Weights – Should they be Heavy To Build Muscle?

By on February 2, 2016

Lifting heavy weights has long been the sure-fire way to gain muscle, but is this really the case?

What you’ll Takeaway –

1. James Krieger’s 2x meta analysis are evidence that using multiple sets results in greater improvements in both muscle and strength, commpared to singleset protocols.

2. Brad Schoenfeld’s recent research (3) suggests that lighter weights promised hypertrophy just as much as heavier load training.

3. It has therefore been suggested that in order to activate and recruit your Type II muscle fibres you need to train with heavier loads. Whereas lighter load training activates and causes growth in slow twitch Type I fibres.

4. It seems appropriate that if you want to build muscle you should train across a wide spectrum of rep ranges and loads.

Weights – Let’s Get To It

It has been shown multiple times now that higher volume workouts, that do no push you past your maximal recovery volume, is the most ‘optimal’ way to train for muscle growth. James Krieger’s 2x meta analysis are evidence that using multiple sets results in greater improvements in both muscle and strength, compared to singleset protocols. (1-2)

Now this is not to say that performing single sets has no use in a program, but if you want to maximise your gains multiple sets are a must. But at what rep range and load should these sets be performed at?

Brad Schoenfeld’s recent research (3) suggests that lighter weights promised hypertrophy just as much as heavier load training. What Brad did was take 18 young men randomly assigned to a resistance training program using either using moderately heavy loads and rep ranges of 8-12RM or light loads, with rep ranges 25-35RM. What they found was that both groups increased lean mass and there was no significant differences between the groups. However, the heavy load group showed significantly greater strength increases and muscle endurance was greater for the higher rep, lower load group. On the surface the results show that hypertrophy can be achieved by training with light loads, there was no difference between using heavy and light loads.

Many people have been quick to jump to the conclusion that they only need to lift loads of around 30% relative to the 1RM to build muscle. But is this right?

In the past everyone thought you had to lift heavy to grow and lifts should be on +65% 1RM, but this research might be showing a new way to train. It has been shown in the past that light loads do no activate muscle as much as heavier loads do. ‘Results indicate that training with a load of 30% 1RM to momentary muscular failure does not maximally activate the full motor unit pool of the quadriceps femoris and hamstrings during performance of multi-joint lower body exercise.’ (3)

It has therefore been suggested that in order to activate and recruit your Type II muscle fibres (fast twitch fibres which are much better at generating short bursts of strength and speed than Type I) you need to train with heavier loads. Whereas lighter load training activates and causes growth in slow twitch Type I fibres.

Conventional wisdom states training for maximal strength requires low reps (1-5) and heavy weights, while muscle size is best achieved with slightly higher reps (6-12) and lighter weights and that is gospel. But Schoenfeld also carried out research comparing a bodybuilding style workout vs a powerlifting workout with matched volume (4.) 20 well-trained subjects were randomly assigned to either a bodybuilding style routine or a powerlifting style routine which both contained the same amount of volume (load x sets x reps.) Strength was measured by 1RM in the squat and bench press and muscle thickness of the biceps was measured with ultrasound at the start and end of the protocol.

The results showed that both groups significantly increased biceps muscle thickness with no differences seen between groups, and both groups also significantly increased 1RM strength, but the powerlifting group had greater increases.

So I can train either as a bodybuilder or a powerlifter right?

You can, but it is important to know the powerlifters trained on average for 70 minutes while the bodybuilding group trained for 17 minutes. Also the powerlifters were exhausted and were burnt out by the end of this trail. While the bodybuilders thought they could have done more. It simply isn’t practical to train constantly with the volumes required for growth like a powerlifter would, if muscle growth is your goal.


It seems appropriate that if you want to build muscle you should train across a wide spectrum of rep ranges and loads. But strength increases are highly specific to the rep ranges used and percentage load. If you want to increase upper 1RM then you need to lift loads that are close to that.

Lighter loads to activate type I fibres and heavier loads to activate type IIs. Even if your goal is to build muscle and get bigger it would still be beneficial to train some lifts in the rep ranges of 1-5, to increase strength allowing you to lift more in the rep ranges of 8-12, and who doesn’t wanna be as strong as an ox?

To quote Greg Nuckols;
‘At least when talking about hypertrophy-based training, it’s more useful to think of “training volume” as “total number of hard sets per muscle” than “sets x reps x load.”’ – Greg Nuckols
Further Reading

1. http://www.ncbi.nlm.nih.gov/pubmed/20300012
2. http://www.ncbi.nlm.nih.gov/pubmed/19661829
3. http://www.ncbi.nlm.nih.gov/pubmed/25853914
4. http://www.ncbi.nlm.nih.gov/pubmed/25113097
5. http://www.ncbi.nlm.nih.gov/pubmed/24714538
Scott Edmed

About Scott Edmed

I am currently serving the Royal Air Force as a pilot with a huge passion for nutrition and training, having competed in physique competitions and playing rugby and cricket for the RAF.