Did you sweat today? Applause. You got moving, got your heart pumping. You did your cardio and you feel like a beast (a pretty one)—just in time for shorts weather. We know you want to show off killer legs and a perky butt and there’s no doubt that cardio will help you get there—fast. But is there such a thing as too much cardio?
Yep, there is. Point in fact: Too much cardio can boost your risk of having heart problems.
Here’s why. Cardio means primarily working the skeletal muscles, the ones that move you body around, creating micro tears that help you get stronger. Cardiovascular exercise also works the soft smooth muscle tissue in your throat and heart. 
But here’s the downside. If the heart muscles get overworked for too long, they bulk up, just like any muscle would lifting heavy weights. Too much cardio can reduce the volume of the blood it pumps as well as the flexibility of the heart tissue itself. Now, you’re still causing those micro tears, but if the heart isn’t given a chance to repair itself—because of repeated bouts of cardio that last hours day in and day out—the tears scar and can cause a rupture. That’s why extreme endurance athletes are at risk for serious cardiac symptoms, including sudden heart failure. Other forms of extreme cardio and exercise can hurt you as well. If you work out so hard that you literally cause your muscles to break down, you can damage the kidneys, elevate cortisol levels (your stress hormone) causing oxidative stress to the cells in your body, and up your risk for depression, metabolic syndrome, and heart problems. Want to work out as hard as you can without getting too much of a good thing? Here’s how to keep your cardio within healthy limits.
5 WAYS TO MAKE SURE YOUR KILLER CARDIO WORKOUT DOESN’T KILL YOU
1. SEE YOUR DOC If you are training for a marathon or an endurance event, make sure to get periodic EKG tests from your doctor to make sure everything is operating correctly.
2. GIVE IT A REST Don’t do consecutive days of 2 hours or longer cardio sessions. Remember that your heart is a muscle and it needs to rest just like your legs, biceps, and other “show” muscles.
3. GO HIGH INTENSITY Complete High Intensity Interval Training—by doing one high intensity exercise for a given period of time, usually 30 seconds to a minute, then resting for a 1:1 or 1:2 ratio, followed by a repeat for 20-25 minutes. This routine gives your body the benefits of long bouts of cardio in a fraction of the time (Bonus: You’ll lose fat!).
4. BE FLEXIBLE Change up your workouts. Don’t forget that you can still get cardiovascular benefits from resistance training in circuits.
5. TAKE A BREAK Don’t be afraid to give yourself a break every now and then. Listen to your body. If you are extremely sore and feel like you need to take a day off, then you do. You will benefit from giving yourself a break so you can get back at it tomorrow. Cardio won’t kill you, just as long as you keep it sane. The standard is at least 30 minutes of physical activity a day. You don’t need to run a marathon to get in to great shape—but if you do, get prepared. Listen to your body, set a goal for yourself to keep motivated, and go for it. To get you started, try this FREE 10-minute cardio workout. NO weights necessary!
