The Endorphin Rush

Endorphins are Mother Nature’s way of encouraging you to exercise. If you've ever experienced post-workout bliss, chances are you’re familiar with the pleasant effects of endorphins. As your muscles work harder, your brain begins to release these mood-enhancing chemicals as natural pain relievers. As a side effect, these little neurotransmitters help boost your mood and contribute to what is commonly called a “runner’s high.” While even casual exercisers are likely to experience the effects of endorphins, the more intense your exercise is, the more significant the amount released during your workout, according to a study published in a 2001 issue of “European Journal of Applied Physiology.”

Cardiovascular Endurance

Intensive exercise forces your heart and lungs to work overtime to supply fresh blood and oxygen to your muscles. This causes your heart rate to increases as you begin to breathe harder in order to withstand the demands of your exercise. Fortunately, over time, your cardiovascular endurance improves to the point that it takes longer and longer to become winded. This is why non-athletes frequently find themselves out of breath after only a few minutes of intensive aerobic exercise. To keep your cardiovascular system in good shape, the American Heart Association recommends 25 minutes of vigorous, intense aerobic activity three days per week.

Burn Calories

Weight loss is perhaps the most frequently advertised health benefit of intense exercise. Simply put, the more calories you burn off in a day, the quicker you’ll find yourself losing weight. Like all exercise activities, the more intensive your workout, the more calories you will burn per hour. For example, an adult walking at a rate of 2 mph can expect to burn 204 to 305 calories, depending on her body weight, according to MayoClinic.com. However, bump that up to a running speed of 8 mph, and you’re more likely to burn between 861 and 1,286 calories. If you’re trying to lose weight, intensive exercise can help you burn more calories each day. In addition to running, other intense workouts include basketball, backpacking, tennis and stair climbing.

Safety Concerns

For all of its benefits, intensive exercise poses a number of dangers to your health. For example, high-speed running can be problematic if you have weak joints in your knees and ankles, or try to run in places full of obstacles like tree roots or rocks. Likewise, intense exercise can also be dangerous if you're not keeping track of your heart rate. The Centers for Disease Control and Prevention recommends determining your maximum heart rate by subtracting your age from the number 220. For example, if you’re 50 years old, your maximum heart rate would be 170 beats per minute. When engaging in intensive exercise, it’s important that you keep your heart rate below 85 percent of this number, for example, 144 beats per minute. Talk to your physician before trying any sort of intensive exercise to make sure you are healthy enough to participate.