When Good Exercise Goes Bad...

Getting your heart pumping with regular cardio exercise is important. As your heart rate rises, the amount of oxygen in your blood improves, and endorphins, which act as natural painkillers, increase.

Meanwhile, aerobic exercise activates your immune system, helps your heart pump blood more efficiently, and increases your stamina over time. But there is a cut off point to these benefits, and if you push your cardio session too long it can actually harm your body, leading to:

• A catabolic state, in which your tissues break down
• Excess cortisol (stress hormone) release, which not only contributes to catabolism but also chronic disease
• Microscopic tears in muscle fibers (which will have trouble healing if you continue over-exercising) and increased risk of injuries
• A weakened immune system
• Insomnia, especially if your workout is in the afternoon or evening

Research emerging over the past several years has now given us a whole new understanding of what your body requires in terms of exercise, and many of our past notions have been turned upside-down. It's now clear that exercising too much can be a serious blow to your health.

Read more: http://fitness.mercola.com/sites/fitness/archive/2012/06/01/long-cardio-workout-dangers.aspx?e_cid=20120601_DNL_art_1