Most injuries are not accidents but ignored signals. What should make you stop.
Training injuries far more often come from pushing through days of discomfort than from a single accident. It hurts only during training at first, then lingers afterwards, then shows up in daily life. What a few days of rest would have settled at the first stage can take months once it reaches the last one.
Muscles aching the day after training is normal. Sharp pain felt inside a joint, pain on only one side, or pain landing in exactly the same spot with one specific movement is different.
What you need before training is warmth, not lengthened muscle. Long static stretching from cold can reduce the force you produce immediately after. Raise your temperature with easy movement that takes joints through their range, and leave lengthening stretches for after the session.
You improve while resting, not while training. Short sleep or insufficient food slows recovery from the same session and raises injury risk. Plans that hit the same area hard every day usually fail, not from lack of discipline but because recovery cannot keep up.
Putting rest days in the plan in advance lets you take them without guilt. Resting only when something hurts means resting after it is already too late. If pain lasts beyond two weeks, or there is swelling or loss of strength, getting it examined is faster in the end than deciding alone.
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