Lactic Acid is BAD
There is a common misconception in the fitness industry that the pain you feel days post workout is due to lactic acid and that lactic acid is a bad thing to have.
Yes lactic acid will cause localised muscle fatigue and a nice often-painful burning sensation when training but that is it. It does not stay in the body and in particular in the muscle post-training. In fact the first time you urinate post training lactic acid is removed from your body.
Your body is pretty efficient at removing substrates that it no longer needs for performance and what it deems to be a surplus or waste products.
Research over 100 years ago suggested that lactic acid levels within the muscles increased with fatigue. As a result it was then deemed that lactic acid was at fault and that it was something, which should be either avoided or minimised to enhance performance.
A little known fact is that this research was conducted on frogs. In particular frogs legs. Now last time I looked humans did not have frog’s legs unless they were a very good breaststroke swimmer.
The fact is that lactic acid does increase as you become more fatigued but the reason is not what you think. It does so as it is providing the energy for your muscular contractions to occur. Yes it does cause the burning sensation but at the same time your liver is breaking it down at a rate of knots and converting it into more energy for you to keep going.
Therefore it is helping you to offset fatigue and to enhance your performance. What makes you stop due to the pain and weakness in the muscles is not lactic acid but the accumulation of protons caused by glycogen breakdown.
So before you go and blame lactic acid for all of your pain think again and praise it instead for helping you to keep going.