Have you ever trained to failure? It is probably one of the most difficult, most satisfying thing you can do in a gym.
Performing a set of ten reps as usual, but then grinding out a couple extra reps until your muscles are shaking and your form is about to fail. This is known as training to muscle fatigue, which was defined by Gandevia (2001) as “an exercise-induced reduction in maximal voluntary muscle force” , meaning that the more reps you perform the force that your muscle can exert will reduce until you cannot perform another rep.
Some studies have found that training to failure results in a greater activation of Motor Units (MU) within the muscle, and the secretion of growth-promoting hormones .
To understand the Motor Unit activation, you must understand the function of MUs in the muscle.
Essentially your muscles are made up of muscle fibres, you activate the fibres to perform a contraction, you do this by sending a signal through the MU. The more MUs signalled, the more fibres activated, the more powerful the contraction.
When you train normally however, your muscles don't need to activate all of the MUs. You have low-threshold MUs that are activated for the majority of the reps while the high-threshold MUs are inactive.
Training to failure forces the high-threshold MUs to activate which means more fibres are used, leading to increased muscle damage, leading to increased strength and hypertrophy of the muscle.
The thing is, not a single study has recommended training to failure long-term, meaning that you should only set aside 6 weeks where you add it in.
Even then, it shouldn't be every single exercise. Just one or two exercises preferably at the end of the session.
As Willardson says (2007) “training to failure should not be performed repeatedly over long periods, due to the high potential for overtraining and overuse injuries” .
How to Train to Failure
There are a number of ways to do this, the most obvious is to literally train to failure.
Grab a weight and perform the desired exercise until you physically cannot lift it without breaking form. You should be using a weight that you can perform around twelve to fifteen reps with, not a weight you can only manage two reps with.
The second way to train to failure is to utilise drop sets, for this you will require two different sets of weights. The normal weight that you use to perform the exercise, and a weight that is around 50% of the weight.
So if you were performing a shoulder press with a 50kg barbell, you would also need a 25kg barbell.
To start with you would perform as many reps as possible with the 50kg weight, trying to maintain perfect form throughout.
If your form drops to 85-90% then don't worry (i.e. the exercise still looks good but you know that it is not as perfect as before), but anything lower than that and you need to drop the weight.
Judging when the moment has hit is the most vital skill needed when drop setting. Once you have dropped the 50kg barbell you need to immediately pick up the 25kg barbell and continue with the exercise.
Absolutely no rest in between lifts just get on with it. Once your form dips below 85% your set has finished, and if you have any sense your workout will have finished too!
There are many other ways to train to failure, you can perform a triple drop set which is exactly the same but with 3 different weights.
Or a run-the-rack which would involve starting at a heavy weight (that you can get 4-6 reps out of) lifting until failure, dropping it to the next highest weight (which you would normally be able to get 8-10 reps out of) and continually dropping it until the lowest weight.
This works really well with exercises such as barbell or dumbbell bicep curls, as you can pick the weights up quickly between lifts.
If you are performing a barbell bench press, or squat you can ‘strip the weights‘ which is almost exactly the same as a run the rack drop set. This works even better on a resistance machine where you can manually change the weight without having to stand up and move plates.
Training with drop sets is a fantastic way to achieve hypertrophy, but is not a great way to build strength or improve athletic performance.
While short training periods involving drop sets are excellent, you shouldn't extend these periods as the effectiveness will wear off fast.
 Gandevia, S. 2001. Spinal and supraspinal factors in human muscle fatigue. Physiological Reviews 81(4): 1725-1789
 Willardson, J. 2007. The Application of Training to Failure in Periodized Multiple-Set Resistance Exercise Programs. The Journal of Strength & Conditioning Research 21(2): 628-31