Many bodybuilders hate cardio. To some, it seems like a waste of time to sit on a bike for 45 minutes.

But champions know cardio is important to getting the shredded look you need to succeed on competition day. During the off season, you can limit cardio. But once you are in a training mode, cardio must be part of the plan.

Cardio will not just burn fat, though—it will also pull oxygen into your muscles. To get maximum results, schedule cardio to 3 to 4 times a week. Try increasing cardio by 5 minutes each week until you are up to your desired level.

For some, that will be 2 hours a day (probably 1 hour in the morning and 1 at night) while others will complete 35 minutes and call it a day.

Does Cardio Make You Lose Muscle?

This is a common concern for bodybuilders and the answer is both yes and no.

When you are doing cardio, you start to burn calories in this order:

1. Carbohydrates

2. Fats

3. Proteins

The challenge for bodybuilders is to stay in the first two categories. Super hard cardio will make your body reach into its muscle cells to keep the energy going. A very general guideline is that this will start to happen after around an hour of moderate to heavy activity.

Admittedly, this is an oversimplification. Carbs, proteins and fat all provide “food energy.” When we workout, we are burning that fuel. Anabolic activity (building up muscle or storing fat) needs an energy surplus. Catabolic activity (breaking down muscle and fat) needs an energy deficit.

So try to stay in the range where your body is burning carbohydrates and fats but not proteins. Runs of 20 to 30 minutes will barely burn any muscle so you should be safe. You can carb-load ahead of time in order to have extra fuel reserves.

Another way to keep your intensity at the right level is to shoot to work at about 65 percent of your maximum heart rate. To find your maximum heart rate, subtract your age from 220 and multiply it by 0.65. This is your ideal heart rate for burning fat.

Stretch It Out

Warming up and cooling off properly is a must for every cardio session. Jack LaLanne, the godfather of bodybuilding, was famous for dismissing the value of warming up before working out. He said, “Does a lion warm up when he’s hungry? No! He just goes out there and eats the sucker.”

However, studies show stretching helps speed up your body’s recovery process by reducing the stress on your muscles, connective tissues, heart and joints. It also increases the range of motion for a muscle—helping create space for new muscle fibers to grow.

Trying to stretch completely cold muscles is not advised though. So, for example, if you are going for a run, try walking a bit before stretching to warm and loosen your muscles.

Don’t neglect the cool down period either. Avoid jumping off your stationary bike and hitting a heavy weight session. Let your heart rate come down while stretching again.

3 More Tips to Capitalize on Your Cardio Workouts

  • Always eat breakfast before exercising if you do cardio in the morning. When you wake up, your body is already in a muscle-burning state. Running an hour without any food in your tank just increases the catabolic state you were in when you rolled out of bed.
  • Try to mix up your cardio routines. Consider circuit-training that includes several different types of cardio in the same session. Or cross-train over your week of work-outs, with running, biking and swimming mixed up on different days.
  • Be sure to get enough sleep. Rest is really under rated in terms of building muscle. When you sleep, your body is repairing the muscle tissue and producing chemicals such as growth hormones. That’s why you can’t lift seven days of week (although we all know someone that does). You need the off days to properly regenerate the muscles.

Love it or hate it, cardio provides important benefits to both your health and your performance at bodybuilding competitions!