Many athletes train too hard for optimal results. They run their longer runs just a little bit too fast, burning up glycogen stores and wondering why they get tired, sore, and injured, and wondering why they can’t shake minor upper respiratory tract infections.
What is happening at the cellular level is that their systems are slightly acidic. Most of the body’s systems, apart from the digestive system, operate best in a slightly alkali environment. Systemic acidosis, or an elevated amount of acid throughout the bloodstream, upsets the function of the aerobic enzymes and the lipolytic (fat-burning) aerobic system where the body gets efficient at metabolizing fats for energy.
To picture more clearly what is going on at the cellular level when there is elevated acid (acidosis), imagine taking a swig of vinegar, and compare that to taking a swig of milk, which is far more alkali. Imagine flicking vinegar into your eyes. Your cellular machinery in your running muscles is very sensitive to fluctuations in acid or alkali; at certain high concentrations of acid, the neuro-muscular system will refuse to operate, no matter how much your brain tells the muscles to contract. The final synaptic connections from your nervous system to the recruited muscle are inactivated by the presence of acid in the region.
To stay healthy year –round, the athlete should never get too far away from the easy fat-burning intensities of extended recovery-level running. This easy, forgiving running is best done before and after hard training sessions; sometimes for several days in a row if a hard training session has increased the acidic load too much for optimal recovery.