Q: What is the difference between the “fat burn” and “cardio” settings on a treadmill? If I’m looking to lose weight, am I limited to only the fat burn programs?
A: I am asked this question at least once a day – no exaggeration. The truth is… Absolutely not. Exclamation point. The cardio machine programs were designed to give you options, to help you out if you are sans trainer, and to point you in the right direction. Each program was designed for a special purpose, sure, but there are health-related benefits and training advantages to each program no matter what your goals.
The main difference between the fat burn and cardio settings on those machines has to do with heart rate. If you’ve tried similar programs in the past, you’ll remember that you probably had to give the machine your pulse – either by strapping something to your chest or holding your palms on the silver handles. Or by making up a number just to get the machine moving (yes, I’ve see you do it!). In all honesty, if you choose the fat burn program because you want to lose fat, then it’s to your advantage to give an accurate heart rate.
That being said, what is Heart Rate?
Literally, heart rate is the number of times the heart beats per minute (abbreviated bpm). Monitoring your heart rate during exercise allows you to monitor exercise intensity* and cardiorespiratory responsiveness. Tracking your heart rate over time can be an excellent way to reveal your fitness progress. In essence, the more fit you are, the lower your pulse will be for a given exercise intensity.
Heart rate can be obtained by feeling the pulse at the neck (carotid artery), the wrist (radial artery), the head (temporal artery), or the chest (apical artery), although the wrist is usually more convenient. To measure, place two fingers (index and middle) on the underside and thumb side of the wrist, feeling for a pulsing sensation. You shouldn’t use your thumb to determine heart rate; it tends to have a pulse of its own. Without pressing too hard, count the number of beats in 30 seconds. Then multiply this number by 2 to get beats per minute (bpm). This is your heart rate.
You can observe the changes in your heart rate during various activities by taking your heart rate at different points throughout the day. To begin with, take your pulse first thing in the morning before you even get out of bed. This is your resting heart rate. For more accurate results, take your resting heart rate three mornings in a row and average the results. You can also choose to take your heart rate before, during, and after routine activities. The higher your heart rate rises above its resting pulse, the more difficult that activity is for your body to perform.
Heart Rate & Exercise Intensity
The optimum exercise intensity for fitness improvement falls within a range of 50-90% of your maximum heart rate (although this figure can vary by fitness level, gender, and/or age). Monitoring your heart rate (and thus your intensity) allows you to exercise at the proper intensity for your fitness level and goals.
As a trainer, I must consider my client’s target heart rate when putting together his or her program. If I prescribe too low of an exercise intensity, my client won’t be challenged and will probably fall short of his/her fitness goals. On the other hand, an intensity that is too high will fatigue my client too quickly, ending the session early and likely causing a painful buildup of lactic acid in the exercising muscles.
How to Determine Your Maximum Heart Rate (HRmax) and Training Range
The least complicated method for obtaining HRmax involves a simple age-predicted equation:
220 – age = Maximum Heart Rate
From there, you can determine the heart rate range you’d like to train at. Remember, optimum exercise intensity for fitness improvement is between 50-90%. Here’s the new equation and an example of how it works:
[220-age (predicted maximum HR)] x [50%-90% (exercise intensity)] = Target Heart Rate
Example:
Suppose you are a 31-year-old woman looking to lose some post-pregnancy weight. Your maximum heart rate would be 220 – 31 = 189 bpm. I would recommend you begin at an exercise intensity of 65% maximum heart rate. Thus the formula would look like this:
(189 bpm) x (0.65) = 123 bpm. This is your “target” heart rate.
I could also have recommended you stay within a target heart rate range of 65-75%. In this case, you would calculate a second number – the upper limit of the range.
(189 bpm) x (0.75) = 142 bpm. Your goal in this scenario would be to stay somewhere between 123 and 142 bpm for the majority of your exercise session.
It is important to remember that this formula contains only an estimate of HRmax. We use the age-predicted equation because age has been found to contribute to 75% of the variability in heart rate. However, several other factors (such as fitness level and type of exercise) can influence maximum heart rate. Additionally, older individuals (older than 65) may have significantly higher maximal heart rates than predicted by the 220-age formula. Thus although age-predicted maximum heart rate is a useful estimation, we must remember that it is only an estimation.
YOUR Heart Rate Zone
Even with all this information, how do you ultimately decide on your ideal training zone? At any given point in the day, your body is using a combination of fats and carbohydrates to fuel your activities (your metabolism). At rest, this percentage is approximately 70% from fats and 30% from carbohydrates. These percentages shift towards carbohydrates as you increase the intensity of your activity until, during high-intensity aerobic exercise, almost 100% of the energy you need is derived from carbohydrates (provided there is an adequate supply).
Given this fact, you can program your exercise session to burn the types of fuel sources you’d like (i.e. more fat or more carbohydrate) by choosing the correct intensity and monitoring your heart rate. This is why there are separate fat burn and cardio programs on those treadmills. The fat burn program (look for 30-60min in the table below) keeps your heart rate in a lower range than the cardio program (65-75% v. 75-85%). Because the fat burn program keeps your intensity down, you should be getting a significant amount of your fuel energy from stored fats. Alternately, the cardio program will increase your intensity; the higher your heart rate, the more carbohydrate stores you will be burning. I’ve compiled a few more examples:
Goal Duration of Workout Intensity of Workout
Weight Loss 30 min or less 75-85% HRmax
Weight Loss 30 – 60 min 65-75% HRmax
Cardio Endurance 20 – 60 min 75-85% HRmax
General Health 20 – 60 min 50-60% HRmax
Important Note: If you will be exercising for 30 minutes or less, then I would recommend keeping your intensity in the cardio range because you’ll burn more calories overall. Even though you burn more fat in the “fat burn” zone, if you’re only working out for a short time-period then you’re better off just blasting calories. Remember, in the end it’s calories in – calories out, plain and simple.
Other Ways to Monitor Exercise Intensity
There are several other ways to monitor exercise intensity besides heart rate, but my favorite for clients doesn’t involve any formulas, math, or tables to understand. You just have to talk! The talk test method, as it’s called, uses the hyperventilation response to monitor intensity. The basic concept is that you should be able to breathe comfortably throughout your workout, especially if you’re new to exercise. A good way to check how hard you’re working? Talk. If you can carry on a conversation with the person next to you (assuming you can tear yourself away from this week’s People long enough…), then you’re exercising below 80% maximum heart rate. The easier it is to speak, the lower your heart rate is.
Cardio machines are pre-programmed with these heart rate-predicted training zone programs just for you – to help you reach your goals faster, to add variety to your workouts, and to act as a virtual trainer of sorts when you’re exercising on your own. So feel free to try out different programs and mix up your routine! This helps fight boredom and those dreaded workout plateaus. Besides, now that you know how to calculate your own target heart rate, you don’t need the programs anyway!
*There are several factors that can influence heart rate besides exercise, so heart rate alone is not an absolute indicator of proper exercise intensity. Please consult with your doctor before beginning any exercise program, especially if you are on medication.
References:
Baechle, Thomas R., Roger W. Earle, eds. Essentials of Strength Training and Conditioning, 2nd ed. Hong Kong: National Strength and Conditioning Association, 2000.
Bryant, Cedric X., and Daniel J. Green, eds. ACE Personal Trainer Manual, 3rd ed. San Diego: American Council on Exercise, 2003.
