The disadvantage of a fixed number of repetitions is that it does not teach you how to save energy. There is no incentive to look for ways to minimize muscle work. But the minus of repetitions to failure is that when the muscles are working to the maximum, the risk of injury increases. In addition, constant limiting overvoltage has a bad effect on the psyche.
Physical education consists of two constant opposite processes – controlled “injury” and recovery. Micro-injuries are usually present at medium load, you almost don’t notice them. At a load above average, a good recovery is already required. And at maximum load, there is a threat to inflict injury dangerous to health and with irreparable consequences.
At loads above average, breaks in physical education become necessary for full recovery. Training every day becomes impossible, days of rest are required. The duration of rest breaks depends on the speed of recovery. And the speed of recovery depends on the current state of the body, the absence of diseases, normal nutrition, or even the weather and mood. And from the ability to accurately assess their condition.
The advantage of exercises with a fixed number of repetitions is that they can be done for medium and minimal loads, usually without even feeling injured. In this case, you can improve the technique, gradually connect the non-working weak muscles, and learn to minimize the effort on the working muscles. Also, exercises with a fixed repetition of the number give you the opportunity to better control the effort and recovery. And for exercises “to failure” the main plus is that they lead to faster muscle growth, and not just maintain the current shape.
But if there are problems with recovery, then in exercises “to failure” the body can involuntarily create a failure itself, through involuntary overexertion or even a cramp. That’s how the saving throw works. You do a few repetitions and the body overstrains uncontrollably, forcing you to immediately refuse to continue, not allowing you to squeeze the maximum out of yourself. Even if you understand it, there is nothing you can do. You cannot always control instinctive overstrain, and then you cannot order your body to continue, it does not obey you.
And the habit of always feeling the pain of maximum effort weans you from a healthy desire to recover to the end. It teaches bad things – not to get rid of injuries and unpleasant sensations completely. You are in a constant anguish, a painful state and you get used to it. And the body begins to refuse against your will, even when there are still forces – to stop you from destruction. At the same time, you overload the psyche, and over time, you may feel disgust for the exercises, loss of interest.
Therefore, it is best to alternate a fixed number of repetitions and work to failure. In contrast, fixing repetitions teaches you to recover and take care of your well-being. No need to get used to constant pain. Because then injuries accumulate and at some point can lead to a dangerous greater injury. We need periods of calm, and the habit of feeling a complete recovery.