DMGLactic Acid, Calcium, and Muscle Fatigue
Wow! New research! On muscle fatigue! I'm excited about this, as it relates directly to my recent studies.
For decades, muscle fatigue had been largely ignored or misunderstood. Leading physiology textbooks did not even try to offer a mechanism, said Dr. Andrew Marks, principal investigator of the new study. A popular theory, that muscles become tired because they release lactic acid, was discredited not long ago.
In a report published Monday in an early online edition of Proceedings of the National Academy of Sciences, Dr. Marks says the problem is calcium flow inside muscle cells. Ordinarily, ebbs and flows of calcium in cells control muscle contractions. But when muscles grow tired, the investigators report, tiny channels in them start leaking calcium, and that weakens contractions. At the same time, the leaked calcium stimulates an enzyme that eats into muscle fibers, contributing to the muscle exhaustion.
The discovery (and the NYT article) is also receiving attention at The Science of Sport, which offers a great nutshell explanation of how calcium plays a part in muscle contraction:
In short, a nerve signal reaches the muscle and stimulates the release of calcium (Ca2+). The calcium is what is actually causing the process of muscle contraction. A special part of the muscle called the sarcoplasmic reticulum, or SR for short, releases calcium, flooding the muscle cells with it. The calcium causes muscle contraction to happen, and when we want to relax the muscle the calcium is then pumped back into the SR, thus causing relaxation of the muscle.
Very cool. I'm sure this understanding will help refine training methods, but we won't see athletes popping anti-fatigue pills; even if they passed FDA approval, they'd quickly join EPO as a banned substance.
So what's the big deal? I'm curious to see how this influences nutritional and training plans.
Runner's World has a few good parting words on the subject:
That still leaves us a proven path to faster marathons: Train long, recover appropriately, run some workouts at your goal pace. When you do this, your body naturally makes all the right biochemistry decisions and adjustments for you. It optimizes your utilization of lactic acid and calcium ions, and you can run longer and faster.
The human body is an incredible machine.