How do you determine heart rate zones?
Most personal trainers and coaches spend a lot of time with their clients doing resistance training, but when it comes to cardio training, many trainers send their clients to a group exercise class or have them get on a treadmill for 30 minutes.
When your client has reached the proper stage of readiness for PA, it will be important to know some CV training programming details.
We want the client to learn how to get the most out of their cardio programs, but the coach has to know how to individualize the cardio workouts to fit their client’s needs and goals. There are two important tools needed to create an effective, challenging program – heart rate training zones and a cardiovascular assessment.
There are many formulas used to determine heart rate training zones, with the most common being, subtract the client’s age from 220 to determine the max heart rate (MHR). A percentage of that number is then used to determine a “fat-burning” zone and an anaerobic threshold. This formula may work for the deconditioned client, but after a few months they are sure to “plateau”. Some trainers prefer to use a variation of this formula, which uses resting heart rate, however, results are not always accurate and do not take genetic traits into account.
Regardless of which formula you prefer, you now have to use a percentage of the MHR to determine training zones. Some formulas state that to determine the individual’s “fat-burning” zone, you would use 65% of the MHR (220-age). A 40-year-old client, for example, would start with 180 bpm (220- 40). Their “fat-burning zone” would be 117 bpm (65% of 180). Most formulas assume that everyone will turn anaerobic 15% (or 80% of 220-age) above the “fat-burning zone”. However, this would not be accurate for anyone with a strong aerobic base as their anaerobic threshold could actually be 5-40% above the “fat-burning” zone. That is why using a straight formula has its limits.
Metabolic testing is the most accurate way to determine heart rate training zones but is not always available. The next best option is to use the formula discussed above, but adjustments must be made as your client’s progress. You must treat cardio training like resistance training – start slowly and increase the workload as the client progresses. With resistance training, you add weights and/or reps, while with cardio training your improvement is based on increased workload (watts, speed, incline) and heart rate.
To adjust the formula you must create a good aerobic base for the client. They can do this by staying at 65% of max for 4-6 weeks. Then add short intervals up to 80-85% of max and see how they react to anaerobic training. You will adjust the heart rate 2-3 beats based on how well they perform.
Even if these charts and formulas give the clients a heart rate to work with, it still doesn’t provide a cardio fitness assessment. There are some very good assessment protocols in the field from which to choose. The more common ones include the Cooper Run Test, Rock-port Walking Test, and Harvard Step Test.
The most commonly used endurance test involves running distances between 600 yards and three miles to evaluate aerobic capacity. The running based tests are based on the assumption that fit individuals will be able to run a given distance in less time or run a greater distance in a given period of time. Cooper’s 12-minute test, which was first used with Air Force personnel, was found to correlate with VO2 max readings.
After observing other such tests, it was determined that most runs that were at least a mile long or 9 minutes in length tended to also correlate with VO2 max. Although performance on a distance run can be accurately measured, it may not be a precise index of VO2max or a substitute for actual measurement of VO2 max. Endurance running performance may be influenced by other factors, such as percent body fat, running efficiency, and anaerobic threshold; but these tests can only really be done on fit individuals.
For the deconditioned client you can use The Rockport Walking Test. This consists of an individual walking 1 mile as quickly as possible and taking the heart rate immediately at the end of the test. Using a chart that graphs heart rate and time, you can tell if your client has a high, average or low cardiovascular fitness level. The drawback is this does not take into account weight, which could overestimate one’s level. The following formula (which was developed and researched by Kline et al., 1987) will give a better indication of VO2 max in the deconditioned client:
132.853- (.0769 x weight in pounds) – (.3877x age) + 6.3150 for males (0 for females)- (3.2649 x time of walk) – (.1565 x heart rate at end of test)= est. VO2max
Another common cardiovascular test is a variation of a step test. The major advantage of using step tests to assess cardiorespiratory fitness is that they can be administered to large groups (i.e. corporate type) without requiring expensive equipment or highly trained personnel. Most step tests use recovery heart rates to evaluate aerobic fitness with the validity highly dependent on the accurate measurement of the pulse rate. While convenient, these tests tend to have lower validity than those using time required for the heart rate to reach a specified level while performing a standardized workload. Of the tests, the Harvard Step Test (Brouha, 1943) and the Three-Minute Step Test (Hodgkins and Skubic, 1963) are most highly regarded.
With technology improving for the fitness industry, we can now do metabolic gas exchange tests with clients in a fitness center. Metabolic gas exchange tests in the past were used mainly to determine an athlete’s VO2 max. While this is usually not needed or preferred for the general fitness club member, submax VO2 testing is reliable and safer for the general public.
Metabolic analyzers measure the client’s VE/ VO2 – (Ventilatory equivalent for O2). The client performs the test on a bike or treadmill with the workload slowly increasing in one- minute increments. Using Wasserman’s definition of lowest VEVO2 as the anaerobic threshold (AT), you can determine what the client’s heart rate is at that point to give you a base for setting all heart rate training zones. The heart rate at the anaerobic threshold is individualized for each client based on fitness level and genetics, not age. For the beginner, the test is completed at anaerobic threshold levels. The client now knows the correct heart rate zone to build an aerobic base. This cuts down on the number of clients that overtrain at the beginning of an exercise endeavor and end up quitting the club in frustration before they see any lasting results.
For more fit clients you can use a metabolic analyzer that also reads VECO2. By reading CO2 you can take the clients up to their “peak” heart rate or when you see the rise in VECO2, which is called respiratory compensation (RC). This is the client’s position at the top of their interval training. Most clients can only hold this level for 1-2 minutes.
With the data provided from the metabolic test ([email protected] AT, VO2 @RC, AT heart rate, RC heart rate, and recovery heart rate), you can actually put together a well-planned cardiovascular exercise program. The first item you look at is the in- dividual’s recovery heart rate. The client should return to 85% of their anaerobic threshold heart rate within two minutes of completing a test to RC. If the client can get back to that level, then they are considered as having a good recovery heart rate. If the client cannot return to 85% of their AT, they have poor recovery and should work on intervals that will help improve their cardiovascular strength.
If an individual has a good recovery heart rate, you can next look at the VO2 score at AT or RC. There are accessible norms for both levels. These norms rate the client low, medium or high. If the client is medium or above, then they are ready to do more intense intervals. To determine these intervals we look for how close the VO2 at their AT is to the VO2 @ RC.
If these numbers are more than 80% apart, then the client is turning anaerobic too early. This means they can do an endurance type program but will not be able to perform at a high level of intensity for long. With a VO2 at their AT above 80% of VO2 @ RC, your client is ready for longer endurance programs or it is time to work on speed and leg strength.
No matter what program you determine is best for your client, you will have their true heart rate zones based on two true heart rates – one at AT and a second at RC. You should set your training zones off AT. With the first zone being 85%-90% of AT. This zone is an aerobic zone that is used for recovery days or recovering between intervals. The second zone is AT to 105% or 110% of AT, (whether you use 105% or 110% is determined by how soon they turn anaerobic) This zone is for endurance training and is used for segments of most group exercise classes. The third zone is from 111% of AT to RC and is used for intervals. Intervals are for the fit individual, so they would have had a test for RC.
Many trainers or coaches have their own percentages and zones from AT and RC that they use for their training, just like they have their own cardio programs. The key for any coach, trainer or instructor is to get a true AT and RC VO2 and heart rate and then design the program based on the client’s needs.
By using cardiovascular fitness tests and determining proper heart rate zones, you can now be more effective in helping clients in their physical activity training. There are two ways that different types of clients present themselves… the ones that have been in the same group exercise class or on the same treadmill for months without seeing any results or new exercisers that need guidance for a long-term cardio program.
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