How does training to failure affect your ability to build muscle? Does it speed it up, slow it down, or make no difference at all?
One of the latest studies to ask that question comes from researchers based at Brazil’s University of São Paolo.
They rounded up a group of men, and got them to train their legs twice a week on the leg extension machine for eight weeks.
With leg extensions, you normally work both legs together. But in this study, the men trained one leg at a time. This meant that each leg could be exercised under slightly different conditions.
Each subject performed two of four different workouts, one for each leg:
– Heavy weights to failure
– Light weights to failure
– Heavy weights not to failure
– Light weights not to failure
The heavy workouts involved training with around 80% of one-rep max, while the light workouts were set at 30% of one-rep max.
In both heavy conditions, subjects averaged 12.4 reps per set when training to failure, and 6.7 reps in the sets not taken to failure.
In the lighter workouts, subjects averaged 34.4 reps per set when training to failure, and 19.6 reps in the sets not taken to failure.
The workouts that required going to failure involved three sets. In the not-to-failure workouts, subjects performed 2-3 extra sets. This meant that each leg was trained with the same number of reps. As a result, volume load (weight x sets x reps) was similar across all four conditions:
– Heavy weights to failure = 34,853 kilograms
– Light weights to failure = 34,576 kilograms
– Heavy weights not to failure = 34,803 kilograms
– Light weights not to failure = 34,592 kilograms
As you might expect, strength gains were greater in the legs trained with heavier weights, irrespective of whether a set was taken to failure or not. In fact, lifting heavier weights increased one rep max by 33%. The legs trained with lighter weights and higher reps gained roughly half that amount.
What about muscle growth?
The quads grew by around 8% in three of the four training conditions. The exception was the light not-to-failure condition, where the quads grew by just 2.8%.
In other words, lifting heavier weights led to an equal amount of muscle growth, irrespective of whether failure was reached. But doing more reps with lighter weights required hitting failure to trigger the same amount of muscle growth.
This is another in a long line of studies to show very similar gains in muscle size across a variety of rep ranges. The amount of weight you lift matters a lot if you want to get stronger, but not so much if your main priority is building bigger muscles (which is one of the reasons my MX4 training program lets you choose from a variety of rep ranges ).
So, does this mean that any set involving lighter weights and higher reps should be taken to failure if you want your muscles to grow?
Not necessarily, and here’s why.
In the leg that was trained with lighter weights, sets were stopped a full 15 reps from failure. It’s not like this study compared training to failure versus leaving a few reps in the tank.
Very few people who are serious about gaining muscle will terminate a set when they’re capable of doing another 15 reps. Even stopping a set with 5-6 reps in reserve, which is what the heavy not-to-failure condition involved, doesn’t pass the reality check in terms of what most people are doing in the gym.
Remember, this study used untrained beginners, who tend to grow no matter what they do. Once you’ve moved past the beginner stages of training, you’ll need to put in a lot more work if you’re serious about making gains.
If I had to pick one of the four conditions to train my legs, it would have been the one involving heavier weights and training to failure. Not only did this training program deliver faster strength gains, it also led to the most amount of muscle growth with the least amount of gym time.
Plus, doing 34 reps to failure is bloody hard work, mentally as well as physically. I’d much rather generate the same amount of growth in a lot less time, and with far less pain.
Maximizing muscle growth does require that you reach a certain threshold of effort, particularly if you’re training with lighter weights, and pushing yourself to the limit is one sign that you’ve crossed that threshold.
However, intentionally training to failure doesn’t need to be the focus of your workouts, and doing so isn’t necessary for building bigger muscles. Cutting a set short with a few reps left in the tank does count as a “hard” set, and will still make a substantial contribution to gains in muscle size.
Christian Finn, M.Sc.
Founder of Muscle Evo