How Much Cardio Do You Need?



Cardio – most people would rather skip it. Yet you need a certain amount of cardio for heart health and to increase your stamina and endurance. Yes, you get some cardiovascular benefits from weight training workouts, especially circuit training. However, additional cardio will help maximize the health of your cardiovascular system. We know that cardio has a variety of health benefits, especially for the heart. For one, it helps lower blood pressure and has favorable effects on lipids.

It has other health benefits as well. Aerobic exercise can lower the risk of heart attacks and strokes as well as reduce the odds of getting other chronic diseases by its effects on blood pressure and lipids and by reducing inflammation. At the same time, aerobic workouts help preserve bone density and improve mental health and productivity. Pharmaceutical companies would love to bottle up these benefits and profit from them but you don’t have to pay a dime to get the benefits.

Unfortunately, some people, especially women, make cardio the bulk of their workout. You’ve probably known people who do an hour or more of running or cycling a day in hopes of burning lots of calories. Not only is this time consuming but you also reach a ceiling on the benefits you gain. Is 90 minutes of cardio really better than 30 minutes? You could argue that spending that amount of time doing aerobic exercise places stress on your joints and increases the risk of injury.

In terms of weight loss, there’s also a point of diminishing returns. One study showed that participants who did moderate amounts of exercise burned about 200 more calories compared to participants who were inactive. Surprisingly, those who did even MORE aerobic exercise burned the SAME number of calories as those who did moderate amounts of cardio. How could that be? Your body adapts to long periods of repetitive exercise, like jogging or cycling, by becoming more efficient. This leads to fewer calories burned per unit of time. Research also shows that we may compensate for long bouts of exercise by eating more.

How Much Cardio 

By now you’re probably wondering how much cardio you really need. Is there a minimum amount you should get for heart health and general fitness? To look at the impact of different amounts of physical activity on heart health, researchers followed more than 400,000 adults over an eight-year period. The participants reported the amount of time they spent doing moderate-intensity exercise. As you might expect, some of the participants moved more than others and some were almost completely sedentary, exercising less than an hour a week. When they measured the heart rates of the participants, they found those who did a relatively low volume of aerobic exercise, the equivalent of about 15 minutes a day, had a healthier heart rate, suggesting improvements in cardiovascular health. The benefits increased with more exercise but only up to a point. For every additional 15 minutes of exercise, their mortality dropped by an additional 4% but the improvements tapered off after about 90 minutes a day.

What does this mean? You can improve your cardiovascular health and decrease your risk of mortality with as little as 15 minutes of moderate-intensity cardio daily. What about high-intensity exercise? Research shows that vigorous exercise has even greater cardiovascular benefits relative to moderate-intensity exercise. Switching 15 minutes of moderate-intensity exercise for 15 minutes of high-intensity interval training is likely more beneficial for heart health and for general fitness.

Strike a Balance 

The point is that you don’t need to be obsessive about cardio or spend an hour every day doing it to get benefits. Even if you’re trying to lose weight, a short, high-intensity interval routine is effective for aerobic fitness and fat loss. Even though a long period of moderate-intensity might burn more calories than a shorter HIIT routine while you’re doing it, the fat loss benefits are potentially greater for the latter.

How do we know this? In a study carried out at Laval University in Quebec, Canada, researchers divided participants into two groups. One group did moderate-intensity cardio for 20 weeks. The second group engaged in 15 weeks of high-intensity interval training. Even though the first group burned 15,000 more calories while exercising relative to the HIIT group, the HIIT group lost more body fat.

One way to explain the discrepancy is the after-burn you get from a high-intensity interval workout. Vigorous exercise is more stressful on your body. Due to the added stress, your body has to expend more energy to repair itself afterward. So, even though you burn fewer calories during an HIIT workout, you make up for it during the recovery period after a session. Plus, a study carried out by researchers at Laval University, showed high-intensity interval training boosts the ability to oxidize fat by 30%.

The take-home message? High-intensity interval training has the advantage of being a better fat burner and offering greater cardiovascular benefits. It improves both aerobic and anaerobic fitness. All in all, it’s a winning approach for increasing your fitness level and the health of your heart.

Cardio and Resistance Training

Is cardio cutting into your weight training time? When you spend too much time doing cardio, you have less time to devote to resistance training.  Plus, excessive cardio may leave you too exhausted to maximize the intensity of your strength-training routine. Resistance training is critical for preserving muscle mass and preventing loss of bone density. In fact, as you age, resistance training may be MORE important. You get some cardiovascular benefits from circuit training. However, you won’t increase muscle strength by doing cardio. The gradual loss of muscle strength and power is what makes us become less functional as we age. The only way to slow this process is to work your muscles against a challenging resistance.

The Bottom Line 

You don’t need long cardio sessions and you don’t need to do cardio every day to get the benefits. A few HIIT sessions a week, as little as 15 minutes in length, is enough to do the job. Don’t be a slave to cardio.

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