We all want to maximise our results in the gym but do we have to kill ourselves getting there?
A common misconception is you must hit repetition failure on every set, even when heavy loads are applied. Pick up the weight, pump out as many as you can until you can’t do anymore? Push yourself to your absolute limits?
Sounds very familiar, so I’m here to explain when fatigue or repetition failure is necessary within our training and the best time to use it.
The relevance of fatigue is task dependent and based specifically on the type of load of the exercise. Research has shown that training to failure is not as important for high loads opposed to lighter loads. The main reason for this is we get similar maximal peripheral fatigue from training to failure on low loads, and not training to failure on heavy loads when volume is equated.
So what does this all mean?
Well first reaching maximal peripheral fatigue is shown to be important to ensure higher central motor output and muscle protein synthesis which results in muscle hypertrophy (growth) and a more effective training stimulus.
During heavy loading (>70% 1RM) the motor unit activation pool is already completely switched on in accordance with Hennemans size principle and as a result this will cause maximal peripheral fatigue without having to train to failure.
So when structuring our training the goal with high load prescription should focus on maximizing volume accrual and progressive overload to the specific needs of the individual rather than training to failure.
For example when heavy loading on a squat (80% 1RM) you wouldn’t do your five working sets all to failure. Otherwise you put yourself at risk of improper technique, poor quality reps, injury and possibly overtraining. Instead you would focus on volume progression such as 5 sets of 5, structure, and quality form for all repetitions.
Now it’s when we come to low loads such as 40-50% maximal voluntary contraction (MVC) it appears that training to failure is required to elicit maximal peripheral muscle fatigue. By training to failure on these low loads it leads to similar levels of central motor output and muscle protein synthesis as higher load training. So to those guys curling light weights every time they step into the gym, I have bad news. It’s not as effective as you might think.
For example performing a leg extension for the quadriceps muscle at a load between 40-50% without going to failure, maximal motor unit recruitment won’t occur as the stimulus will not be enough to recruit the full motor unit pool or maximal peripheral fatigue.
If we are implementing low load to failure training into our own or clients program we must remember it is draining and very hard to do in every set of our workout and not optimum for compound lifts. This type of training may aid in people such as the elderly and rehab clients as there is a much lower risk of injury lifting light weight as opposed to a high load program.
The take home message:
Both high load and low load (to failure) training will give an optimum training effect and should be prescribe based of your own and client’s needs with the main focus still on progressive overload in volume overtime for each muscle group. The prescription of exercise should also be specific to the goals of the individual. If the person aims to enhance strength, lifting at higher intensities of 1RM is recommended.