You may be confused about exactly how hard to work during cardio. You may even think that high intensity exercise is the only way to go. After all, you can burn more calories and, even better, you don't have to spend as much time doing it. But having some variety can help you stimulate all of your different energy systems, protect you from overuse injuries, and help you enjoy your workouts more.
High Intensity Cardiovascular
For our purposes here, high intensity cardio falls between about 75% to 85% of your maximum heart rate (MHR) or, if you're not using heart rate zones, about a 6 to 8 on this perceived exertion scale. What this translates to is exercise at a level that feels challenging and leaves you too breathless to talk much. You're not going all out, as in sprinting as fast as you can.
There's no doubt that some high intensity training work can be helpful for weight loss as well as improving endurance and aerobic capacity. For example, a 68kg/150lbs. person would burn about 225 calories after running at 9.6 kph/ 6 mph for 30 minutes. If this person walked at 5.6 kph/ 3.5 mph for that same length of time, he would burn 85-90 calories. But, the number of calories you can burn isn't the whole story. If you do too many high intensity workouts every week, you risk:
- Overuse injuries
- Inconsistent workouts
- Growing to hate exercise
If you're doing several days of cardio each week, which is what is recommended for weight loss, you would probably want just 1 or 2 workouts to fall into the high intensity range. You can use other workouts to target different areas of fitness (like endurance) and allow your body to recover.
Some examples of high intensity workouts:
20-minute workout at a fast pace
You can use any activity or machine, but the idea is to stay in the high intensity work zone throughout the workout. You'll find that 20 minutes is usually the recommended length for this kind of workout and most people wouldn't want to go much longer than that
Is a way to incorporate high intensity training without doing it continuously. Alternate a hard segment (e.g., running at a fast pace for 30 to 60 seconds) with a recovery segment (e.g., walking for 1 to 2 minutes). Repeat this series for the length of the workout, usually around 20 to 30 minutes.
Moderate Intensity Training
There are a variety of definitions of what moderate intensity exercise is, but it typically falls between about 60% to 70% of your MHR (a level 4 to 6 on this perceived exertion scale) The lower end of this range usually incorporates the 'fat burning zone.' That means can carry on a conversation without much difficulty and you feel pretty comfortable with what you're doing.
Moderate intensity workouts have some great benefits such as:
- Comfort-Hard workouts are, well, hard. It takes time to build up the endurance and strength to handle challenging exercise. Moderate workouts allow you to work at a more comfortable pace, which means you may be more consistent with your program.
- Better health-Even modest movement can improve your fitness while lowering your risk of heart disease, diabetes and high blood pressure.
- More choices-High intensity workouts will usually involve some kind of impact or, at the least, a fast pace. But, you can usually get up into the more moderate heart rate zones with a variety of activities, providing you work hard enough. Even raking leaves or shoveling snow, if you do it vigorously enough, can fall into that category.
For weight loss purposes, you would likely want the majority of your cardio workouts to fall into this range. Some examples:
- Walking 10,000 steps a day
- 30 to 45-minute cardio machine workout
- brisk walk
- Riding a bike at a medium pace
Low intensity exercise is considered to be below about 50% to 55% of your MHR, or about a level 3 to 5 on this perceived exertion scale. This level of intensity is no doubt one of the more comfortable areas of exercise, keeping you at a pace that isn't too taxing and doesn't pose much of a challenge. This, along with the idea that it burns more fats, makes this a popular place to stay. But, as we've learned, you can burn more calories if you work harder, and that's what you want for weight loss.
That doesn't mean that low intensity exercise has no purpose. It involves the kind of long, slow activities you feel like you could do all day and, even better, activities you usually enjoy such as:
- Taking a stroll
- Light gardening
- A long, slow bike ride
- A gentle stretching routine
- Regular exercise can help you burn fat and lose weight. But, it's not just about the calories you're burning. It's also about the adaptations your body makes when you exercise on a regular basis. Many of those adaptations lead directly to your ability to burn more fat without even trying. When you exercise regularly, your body:
- Becomes more efficient at delivering and extracting oxygen. Simply put, this helps your cells burn fat more efficiently.
- Better blood circulations. This allows the fatty acids to move more efficiently through the blood and into the muscle. That means fat is more readily available for fueling the body.
- Increases the number and size of mitochondria, also known as cellular power plants that provide energy for the body.
Tips for Consistent Exercise
- Schedule some exercise time every day, even if it's just a few minutes.
- Split up your workouts. You can get the same benefit from short workouts spread throughout the day as do with continuous workouts.
- Change daily routines to incorporate activity. Park at the edge of the parking lot at work to add more walking time, or add an extra lap at the mall when shopping. Integrating more activity into your usual routines will help you stay active, even if you don't have time for a structured workout.
- Make exercise your focus and schedule the rest of your day around it instead of trying to squeeze it in when you can. If it's not a priority, you won't do it.
Adding more muscle by lifting weights can also help with burning fat, especially if you're also dieting. Lifting weights:
- Preserves muscle mass, if you diet to lose weight, you actually risk losing muscle as well as fat. Muscle is metabolically active, so when you lose it, you also lose the extra calorie-burn muscles can provide.
- Keeps your metabolism going, some studies have found that a diet-only approach to weight loss could lower a person's resting metabolic rate by up to 20% a day. Lifting weights and maintaining muscle helps keep the metabolism up, even if you're cutting your calories.
- Helps you burn extra calories, if you lift weights at a higher intensity, you can actually increase your after burned or the calories you burn after your workout.