The idea that lactic acid causes muscle fatigue and stiffness during exercise is a stubborn one. It has been discredited by scientific research, but many fitness enthusiasts still see lactic acid as an enemy that interferes with performance.
Not only does lactic acid(which in the body is in the form called “lactate”) not cause muscle fatigue, it is actually used as an important fuel during vigorous exercise.
This myth goes back to the early 20th century, but it was fully discredited only recently.
All this begs the question: What is causing the fatigue and stiffness that was once blamed on lactate? According to researchers at Columbia University, it may be caused by overworked muscles leaking calcium, among many other factors. And acidity in general in fatigued muscles may play a role in stiffness and fatigue, it’s just not the lactate causing most of it.
So what’s the solution? The idea of calcium leakage partially causing muscle fatigue doesn’t mean most people should consume less calcium, as this is a vital mineral(it is possible to get too much, and it can cause problems but this is rare). However, and I am just speculating here, maybe ensuring adequate vitamin K consumption can help prevent this a little, since it helps with calcium metabolism, along with making sure you get enough magnesium. Calcium helps muscles contract, magnesium helps them contract as well as relax; if you have too much calcium in your body relative to the amount of magnesium, this can be problematic(in fact, not getting enough magnesium may be detrimental to your heart).
It is relatively east to get enough magnesium if you eat like a rabbit – lots of leafy greens, nuts, and whole grains. Fermented vegetables are an especially good source of vitamin K. If you are taking calcium supplements, it may be a good idea to take supplements that combine magnesium with the calcium, to counteract the potentially negative effects of calcium. Try discussing this with your doctor or pharmacist.
Proper hydration and making sure you are getting the right amount of electrolytes helps too. I don’t think stretching would help, since just because a muscle is stiff doesn’t mean it needs to be stretched. Increasingly, science is showing that stretching is practically useless for most people.