Most people know the story of Goldilocks and the three bears; as Goldilocks rummaged through their house she found that poppa bear’s porridge was too hot, momma bear’s was too cold but that baby bear’s was just right. This story is representative of how many people approach cardiovascular exercise; some people are poppa bear and do too much high intensity exercise, others are momma bear – not working hard enough with only a few appearing to be like baby bear: doing exercise at the appropriate intensity for their fitness needs.
The prevailing thought is that aerobic conditioning, commonly referred to as ‘cardio’ short for cardiovascular, is used for fat loss, however there are other reasons for doing conditioning work on a regular basis. Whatever your reason for doing aerobic exercise it’s important to note that consistently exercising at too high of an intensity could create the metabolic damage that results in overtraining which can keep you from reaching your goals. On the other hand exercising at too low of an intensity may not burn enough calories for weight loss or provide the necessary overload to improve aerobic capacity. Identifying the most effective training intensity for your needs requires understanding the role that heart rate plays in measuring the physiological changes happening in your body during exercise.
Knowing how to measure and use your heart rate is essential if you want to get the best results from your exercise program. Here are a few considerations for how to use heart rate to identify the most appropriate exercise intensity for your needs.
1. First, invest in a heart rate monitor. If you are serious about your fitness then wearing a monitor can help ensure that you’re training at the right intensity to reach your goals. The most affordable monitors will only measure your heart rate during exercise while the most expensive models can include a GPS system to track your distance covered, measure calories burned during a workout (it’s an estimate determined via an algorithm based on age, weight, gender and heart beat) or sync with your computer to store all of your training information.
There are different types of monitors, some use a strap around your chest to read the frequency of your heart rate and then send that information to a watch allowing you to see the heart beat in real time. Personally I’ve used Polar for years and currently rock a M400 which also includes a general activity monitor and I’ve set reminders that set off an alarm if I’ve been sedentary for too long. Overall I like Polars but sometimes the monitor doesn’t read correctly and I’ve either become a zombie because it’s not registering a heart beat or I should be dead because my heart is beating too fast – but I chalk that up to interference from other RF signals in the immediate area.
The second kind can be worn on the wrist without any need for a strap. There is a slightly larger margin of error for a monitor worn on your wrist but wearing a strap around the chest can be uncomfortable so it is nice to have that option. Many popular cardiovascular machines in health clubs can sync with your chest unit to show your heart beat on the display of the machine. A tachometer measures how fast a car engine is running; think about a heart rate monitor as a tachometer for your body, it will tell you have fast your engine (the heart) is running.
2. Once you’ve invested in a monitor you can use it to identify the most effective training zone(s) to use for your goal. A training zone is a range of heart beats and represents specific levels of exercise intensity. There are various models of heart rate training zones that can help you determine the appropriate intensity for your needs. The American Council on Exercise recommends a three-zone model based on identifying the heart rate at specific metabolic markers, namely the first and second ventilatory thresholds (VT).
3. The first VT (VT1) is the point where the body transitions from aerobic metabolism, which uses oxygen and fats to create adenosine triphosphate (ATP) the chemical that fuels muscle contractions, to anaerobic metabolism. The Talk Test can be used to identify the heart rate at VT1 and Zone 1 then becomes the training intensity where the body is most efficient at using aerobic metabolism. Wearing a heart rate monitor then allows you to perform steady state (SS) exercise in Zone 1 at an intensity just below VT1 helping you to improve your aerobic capacity allowing you to utilize fat as a fuel source at higher exercise intensities. The Talk Test is easy to perform and can be done on any piece of exercise equipment that allows you to gradually adjust intensity.
4. The second VT (VT2) identifies the heart rate at the Onset of Blood Lactate (OBLA) and is often referred to as the lactate threshold. VT2 can be determined using a field test. Zone 2 becomes the heart rates above VT1 but below VT2 and is the intensity where your body most effectively uses anaerobic glycolysis, the breakdown of glycogen, to create ATP.
Zone 3 is at or above the OBLA and is where the body relies primarily on ATP stored in muscle. Two factors limit the ability to train in Zone 3 for any extended period of time: there is a limited amount of ATP stored in muscle that is quickly depleted and there is a rapid accumulation of metabolic waste that quickly changes blood acidity. Training in Zone 3 should be followed by a period of time in Zone 1 to allow the removal of metabolic waste and the replenishment of ATP in the muscle cells.
5. High intensity interval training (HIIT) workouts are popular because they can help burn a large amount of calories in a short period of time. HIIT workout programs feature work intensities at or above OBLA (in Zone 3) with recovery periods below VT1 (in Zone 1). Even though you are exercising at a lower intensity keep in mind that you are still burning calories in a Zone 1 active recovery interval because you are not only still exercising but your body is expending energy as it functions to remove waste and produce new ATP. Wearing a heart rate monitor can help you determine that you are at the necessary exercise intensity to allow for an appropriate recovery after a high intensity interval.
6. SS aerobic training in Zone 1, SS anaerobic training in Zone 2 or HIIT in Zone 3 each produce specific outcomes. In Zone 1 you can sustain low-to-moderate physical activity for an extended period of time. In Zones 2 and 3 the by-product of anaerobic metabolism accumulates quickly which limits the length of time you can sustain exercise at those intensities. Training in all three zones will help you burn calories but having the ability to measure your heart rate and knowing how to identify your training zones provides you with a customized workout plan based on how your body responds to exercise.
The take-away is that your specific training goals will determine which zones to use and how long to exercise in each. High intensity workouts can help burn calories but lower intensity steady-state workouts are still effective for aerobic conditioning without the high stress loads on the body; both are effective but only you can identify the most effective level of intensity for your specific fitness needs.
Keep in mind that exercising hard is only part of the equation knowing how to exercise smart by monitoring your training intensity can help you achieve long-lasting results, but no matter what your specific fitness-related goals are one of the best reasons to exercise is because it can simply help you to FEEL BETTER. The most important, and often overlooked component of fitness, is what you do for recovery AFTER the workout is over – how you recover from your workout today will determine how you train tomorrow. Wearing a monitor can help you monitor intensity so that you’re training smarter, not harder and that you are in the baby bear zone for each workout (the right zone for your fitness needs).