Written by Will Slatter
What Is Training To Failure?
Training to failure is the state when you can’t complete any more repetitions with proper form. This is due to a reduction in maximal force production in a muscle, and marks the point at which your muscle has reached fatigue. So, what mechanisms are responsible for muscle fatigue? There is no single cause for muscular fatigue, and the mechanisms involved are highly dependent on the task that has caused failure (1). There are two main types of muscle failure: neural and muscular.
When you are using your body at a maximal level, whether it is lifting the heaviest weight possible, or completing a HIIT workout at maximum intensity, your central nervous system is firing rapidly to make your muscles produce the required force and speed for the task. Without time to recover, your central nervous system can tire, and will start to send fewer signals to the muscles. If the muscles receive less stimulation, they consequently produce less force. This central fatigue can take place anywhere from your brain, through to the nervous system connecting your brain to your muscles. Neurotransmitters are the chemicals responsible for relaying electrical signals down nerves, and one proposed theory for neural fatigue is that these neurotransmitters are affected by intense exercise (2).
Neural fatigue can take weeks or months to recover from, and may explain why sometimes the day after a heavy leg session, your performance on chest may be compromised. Compound movements such as deadlifts or Olympic lifts are more likely to cause neural fatigue than isolation movements, as big movements use greater muscle groups.
Muscular fatigue however is where the muscle receives adequate stimulation from the brain, but is unable to perform maximally due to intramuscular mechanisms. It is more likely to occur when an individual has been lifting a sub-maximal weight but at high volume, with many sets and reps.
There is again mixed beliefs on how it happens, one theory suggests when muscles require energy, and there isn’t enough oxygen being delivered to the muscle, it breaks down glycogen for energy. This results in inorganic acids, including lactic acid, being released (3). These acids can cause less calcium release in the muscle, and reduce sensitivity to calcium, which is vital for muscle contractions (4). Compared to neural fatigue, muscular fatigue takes less time to recover from, sometimes only a day or two.
Benefits of Training to Failure
There are several benefits to training to failure, with research reporting greater strength gains in athletes who trained to failure rather than non-failure (5). Another potential advantage is methods to reach failure, such as drop sets, which can help to recruit different muscle fibres to the ones used in the working sets.
Recruiting more muscle fibres can result in more metabolic stress on the muscle, more muscle damage, and greater growth. Your body may also be accustomed to your normal training, and the methods below can add a different stimulus to shock your muscles into growth to help you overcome plateaus. Muscular endurance may improve, as your body adapts to higher repetitions than it is used to.
What Methods Can You Use To Train To Failure?
Generally training to failure should be implemented towards the end of a workout, or at least towards the final set of an exercise, as it may influence performance in subsequent sets and exercises. Below, we list several ways to help push to failure, and get the most from your muscles.
During the last set, continue with the same weight until you can’t complete any further reps. At this point, immediately switch to a lighter weight, and continue with the exercise. Even though you may be unable to continue with the heavier weight, your body will be able to complete further reps with a lighter weight. You may even want to drop the weight for a second time immediately after the first drop set.
Normally you will hit failure on the contracting part of the rep, but this doesn’t mean you have hit failure with the stretching part of the rep. With the help of a partner during the concentric (contracting) part of the rep, try to control the eccentric (stretching) part of the rep by yourself. For example, if you have reached failure on a pec dec machine, then get your partner to help you to bring the arms of the machine together, but then control the tempo of the arms as they move back by yourself.
If you are no longer able to complete reps in the full range of movement, then continue to complete reps for the part of the motion that you still are able to. It may look a bit silly, but it will still help achieve failure throughout the full range of a contraction. If you are doing bicep curls and can’t bring your forearms past 90 degrees, then continue with reps in that lower part of the motion. An alternative is to use ‘cheat reps’ and use some momentum to help achieve the full range of movement.
Free weights vs. Machines
When using free weights, small supporting muscles are working alongside the main muscle groups to help with balance and stability. On the last set, if you switch from free weights to a machine with a similar movement, then it can help you to put more emphasis on the main muscle groups, and means you can worry less about the stabilisation. For example, if you complete a bent-over row with a 50kg barbell and hit failure, then you may be able to complete further reps on a seated row machine, even if you continue to use a 50kg stimulus. This is another way to engage muscles even after reaching failure.
If training with a partner, get them to help you with an extra couple of reps once you hit failure. Your partner should only help as much as is required for you to complete the reps. It is similar to a drop set as the partner will effectively take care of some of the weight, however the advantage of assisted reps over drop sets is that your partner can help you with the part of the movement that you are struggling most with, while leaving you to complete other parts of the repetition by yourself if you are able to.
How Often Should You Train To Failure?
This is where the conflicting opinions come into play. It has been suggested that if you train to failure too often, your body will experience central nervous system fatigue. Until you allow adequate recovery time, then you will be unable to train at the same volume and intensity that you are used to. This is a highly individualised after-effect, and it requires you to gauge your own progress, and decide whether your body is recovering from training to failure in time or not.
Take Home Messages
#1 Training to failure can help provide a novel stimulus to muscles to overcome plateaus.
#2 There are several methods to ensure your muscles work to failure, including drop sets, negatives, and assisted reps.
#3 Neural fatigue can affect performance in subsequent training sessions, and should be used sparingly.