In the animal kingdom, few species actually run for fun. Humans are the exception - we push our bodies to the extreme by willingly running long-distance in races, like marathons. A marathon is a whopping 26.2-mile test of endurance. But how does the body respond during and in the aftermath of a marathon?
Along with the glorious sense of accomplishment, marathon runners can expect pain - and lots of it. The body uses every single type of muscle fiber during long-distance running, leaving runners desperately sore for weeks afterwards. But perhaps the muscle that takes the worst beating is the heart. During a marathon, the heart beats much faster than usual. It also releases an increased amount of metabolites into the bloodstream. One of these metabolites is known as the cardiac troponin enzyme, which at high levels, can signal the onset of a heart attack.
Simple hydration needs can also turn complicated during a marathon. Drinking too little fluid can lead to thickened blood, which stresses vital organs like the kidneys, and impairs the body's ability to regulate temperature. Conversely, when runners overcompensate with too much fluid, their sodium levels get thrown out of whack, which could lead to serious brain injuries.
As with any major physical endeavors, training is key. And though the pain may be unavoidable, some say the memory of pain is ephemeral while the high of finishing a marathon lasts forever.