Heat & Muscle performance---no reason for death or medical emergencies in HS Football practice
But what does overheating have to do with fatigue in the first place? Much of the lab's recent research can be summed up with Grahn's statement that "temperature is a primary limiting factor for performance." But the researchers were at a loss to understand why until recently. In 2009, it was discovered that muscle pyruvate kinase, or MPK, an enzyme that muscles need in order to generate chemical energy, was highly temperature- sensitive. At normal body temperature, the enzyme is active – but as temperatures rise, some of the enzyme begins to deform into the inactive state. By the time muscle temperatures near 104 degrees Fahrenheit, MPK activity completely shuts down. There's a very good biological reason for this shutdown. As a muscle cell increases its activity, it heats up. But if this process continues for too long, the cell will self-destruct. By shutting itself down below a critical temperature threshold, MPK serves as an elegant self-regulation system for the muscle. "Your muscle cells are saying, "You can't work that hard anymore, because if you do you're going to cook and die,'" Grahn said. When you cool the muscle cell, you return the enzyme to the active state, essentially resetting the muscle's state of fatigue. The version of the device that will be made available commercially is still being tweaked, but the researchers see applications for heat extraction in areas more important than a simple performance boost. Hyperthermia and heat stress don't just lead to fatigue – they can become medical emergencies. "And every year we hear stories about high school athletes beginning football practice in August in hot places in the country, and there are deaths due to hyperthermia," said Heller. "There's no reason why that should occur."
Sent from my iPad
