Determining the appropriate level of exercise intensity can be one of the most difficult tasks that we personal trainers face when designing programs for our clients. Intensity level often becomes an estimate because we often rely on the individual’s perception of effort to figure out how hard he or she should be working. This tricky variable can also be affected by seemingly simple factors that become more complicated when added into the “intensity” equation, such as medications, stress, sleep, physical movement (history of, recovery from, and task at hand), temperature, dehydration, time of day, altitude, humidity, illness, food intake (including what type and timing), etc. (Edwards, 2007). With all of these factors at play, the most valuable tools we can utilize in determining the appropriate intensity for our clients are biofeedback mechanisms.
There are many kinds of biofeedback mechanisms, and in Part 1 of this article we will discuss the specific importance of heart rate monitors as a biofeedback mechanism, and their ability to help determine the right intensity of exercise for a fitness client. In Heart Rate Monitoring, Part 2: Getting a Psychological Edge with Biofeedback, we will discuss the behavioral and psychological implications a heart rate monitor as a biofeedback mechanism can have on the exercising individual.
Importance of Biofeedback Mechanisms
When it comes to biofeedback, a lot of the variables in determining metabolic demand are relegated to an exercise laboratory-testing center where things like VO2 max and blood lactate can be measured to determine exercise intensity (Karp, 2009). But let’s be realistic; we can’t exercise clients in a laboratory every day, so we must instead rely on the body’s most easily measured physiological indicator of intensity: the heart rate. Using heart rate as a variable to monitor intensity will not only give you an idea of where your client is beginning in terms of fitness level, but it will also allow you to monitor the client's physiological feedback and progress throughout the program. When monitoring heart rate we get millisecond-by-millisecond data of how the body is responding to the exercise and we can then dictate the intensity more appropriately to fit the individual client’s needs.
Below is a chart outlining the different heart rate zones, including Heart Rate Reserve (HRR), VO2 max, and time under tension:
||Time Under Tension
||45-60 min, up to 90
As stated previously, many factors are at play in the intensity equation, and they can all have some effect on the heart rate. Medications, for example, may stimulate or depress heart rate, which will need to be taken into account when that individual exercises. When training an individual who is taking a medication that is a beta-blocker and slows down the heart rate, an exercise that elicits a heart rate feedback of 80% HRR for that individual may truly be their 90% HRR (Bryant & Green, 2010). Had you not utilized the heart rate monitor to get that biofeedback, you would be left with two possible scenarios. First, you might push them to overexert themselves, putting their heart and body in danger. Second, you may not push them enough for fear of overexerting them. The biofeedback mechanism simply takes the guesswork out of it, and gives you the actual visual of how hard to push them.
On the other hand, you may have an athlete who, unbeknownst to you, is borderline dehydrated. You begin to train them and after the warm-up they proceed to do their assigned workout, which is 4 sets of some type of running drill at the same speed each time with ample rest in between. Their HR is 70% during the first set, and as each set continues, their heart rate continues to climb, even though their intensity/speed has not changed. They are showing signs of cardiac drift, which is defined as a rise in the heart rate during exercise that occurs as a result of loss of blood volume stemming from dehydration (Edwards, 2007). Without a heart rate monitor to help guide the workout, the athlete may have been unable to complete the workout or had additional problems, possibly leading to more missed training.
For more in-depth information about the different heart rate zones, watch this video from PTA Global on Energy Development System (ESD) gears in training.
Taking the Guesswork out of the Training Equation
Heart rate indicates more than just a number; it can also give us very valuable information about energy system utilization. Every individual is equipped to utilize different energy systems at different intensities of exercise, and which energy system we use depends on each individual’s level of fitness. Additionally, the energy system that we use will dictate which fuel source we rely on in the body (Bryant & Green, 2010), which can have a staggering affect on your goals, whether they be weight loss, lean body mass, sports performance, or general wellness.
Understanding that heart rate can correlate to energy systems is vital in getting individuals to their goals. Without biofeedback mechanisms like heart rate monitors, this is impossible unless you can draw someone’s blood and quickly test it while they are performing the very exercise you hope is eliciting the response needed in their body to get them to their goal.
Besides the actual ability to see what is going on within the body during exercise, heart rate monitors can also help to monitor how our bodies respond before and after exercise. When we can see the state of the body before exercise, we can recognize whether or not we need to tweak the acute variables that will dictate the intensity of workout, should our client come to us in an already heightened or stressed state that day. Knowing where we start, in terms of heart rate, can lead to a very effective exercise session that does not detract from the program goal.
After a workout, biofeedback can tell us how quickly the client’s body recovers and whether or not he or she needs more time between workouts. Having the heart rate monitor track this kind of progress day to day and from workout to workout gives us tangible proof that clients are improving and making progress in their programs. Although we can get millisecond feedback within the workout, we must also take a global look at heart rate to understand its true effectiveness. Heart rate readings should be evaluated over time to understand each individual’s history and response to exercise and the intensity variables (Edwards, 2007).
How Common Fitness Myths Give Biofeedback-Based Training a Bad Name
There are common misconceptions about heart rate monitors that can undermine their effectiveness.
Myth #1: “No pain, no gain, right?
If my client doesn’t appear out of breath or sweaty the entire workout, then it’s not an effective workout.”
This myth leads some trainers to use a heart rate monitor to gauge an intensity that is high (80+% HRR) the entire workout. We may think that getting someone to their highest heart rate and keeping them there as long as possible is optimal, and we proceed to do this every workout the client does. In fact, the relationship between heart rate variation and health outcomes is quite relevant. The heart as a muscle must also have variety in its training, as “decreased heart rate variability has been associated with increased cardiac mortality and morbidity” (Gervitz & Lehrer, 2003). What’s scary about this statement is the fact that CVD (cardiovascular disease) is one of the leading killers in many countries across the world, and those that are at risk for CVD are told they need to exercise. So people with CVD begin exercising at a steady state (or continuous heart rate, whether it be high, low, or even moderate) simply because they don’t know any better. Their cardiovascular workouts would be much more effective if they included frequent bouts of intervals amidst their steady state training; they would begin to increase heart rate variability and decrease their risk of cardiac mortality.
“The cardiac system, like most biological systems, demonstrates constant variation when in a healthy (or homeostatically balanced) state.” (Gevirtz & Lehrer, 2003). “A universal principle to training is that it is necessary to progressively perform higher intensities of exercise to effectively challenge and overload the cardio respiratory system… Generally, these intensities are not sustained through steady state exercise.” (Bryant & Green, 2010).
Think about it…your body (heart) must work a lot harder to go from 50%HRR to 90%HRR+ and then back down to 50% HRR than it does to sustain some specific intensity over a period of time. Heart rate variability workouts look a lot like intervals. We can play with many acute variables to program workouts that increase heart rate variability. These acute variables can include exercise order, exercise tempo, exercise range of motion, volume of exercise, load (weight), direction/distance/height of exercise (termed: triangulation by the Gray Institute), etc.
Knowing that heart rate variability is important to cardiac health and decreases the onset of CVD, we can truly recognize the importance of biofeedback mechanisms such as heart rate monitors in evaluating the effectiveness of each workout. Thus, we are no longer playing the “no pain, no gain” game.
Myth #2: Heart Rate Recovery is an unimportant variable in training.
This myth stems from the first . Since most exercisers remain at that constant heart rate for all of their workouts, they ignore the value of what true heart rate recovery can do for the body.
Heart rate recovery is the ability of the heart as a muscle to return to a lower heart rate zone in a short amount of time (Edwards, 2007). The quicker the heart can recover, the stronger it is. It is a well-known fact that the body will take the path of least resistance, and if the heart rate goes up, it’s going to try to get it back down as low as possible as quickly as possible so it does not have to work as hard.
Heart rate recovery is a quick tell-all of a client’s level of fitness, and can also reveal overtraining. Heart rate recovery is a valuable indicator of how and when training intensity should be tweaked to get an individual to their goals without overtraining them. Heart rate recovery and how it is trained can be applicable to the individual’s training goals as well.
For example, an elite athlete who plays right forward on a soccer team may have to run at a steady state heart rate of 70% HRR for most of the game, but the position of right forward demands some all-out sprints during certain moments of the game that gets their heart rate to 95% HRR. After their sprint, he must continue to play, yet he must recover his heart rate back down to 70%, and do it while moving. His training may look a lot like continuous exercises in Zone 3 (70-79%) HRR and then a quick burst up to 95% HRR, followed by an exercise that brings him back to Zone 3.
On the other end of the spectrum, you may have a client whose goal is wellness, and her heart rate recovery occurs as a rest period after a weightlifting circuit. During the circuit, she gets her heart rate up to 85% HRR and afterwards takes an active rest utilizing a stretch or mobilizer to get her heart rate back to Zone 2 (60-69%) HRR. How long the client takes to recover to that lower zone will indicate her level of fitness as well as what work-to-rest ratios to utilize in her training.
Without having the feedback of a heart rate monitor it would be hard to tell whether or not the client is truly ready to continue the circuit and raise the heart rate again. The feedback becomes the guide of the workout, matching the client, move for move, and heartbeat for heartbeat. Giving the body truly what it needs every second of the workout.
When we train heart rate variability and heart rate recovery we hit all the key points, and this is almost impossible to accomplish without biofeedback.
To see the differences in individual biofeedback and how heart rate variability and heart rate recovery differs from individual to individual, watch out this video:
Without having quick physiological feedback on how each individual exercise is affecting the body, we are ultimately just playing a guessing game in our fitness programming and training. As personal trainers, we are left to rely on visual clues such as respiratory rate, fatigue, level of skill execution, or even verbal statements from the client, which can be biased based on what they think the intensity should feel like. This leaves the workout intensity to be dictated by the emotional and psychological feelings the workout brings the client versus what the actual body is telling us physically through biofeedback.
As discussed earlier, biofeedback gives trainers a gauge of physiological intensity, but that is only one positive side to using biofeedback. The incurring behavioral change that biofeedback elicits is outstanding and warrants our attention as well. In Part 2, we will look at the psychology of biofeedback mechanisms and learn how they propel behavioral change through continuous reinforcement of positive expectations and perceived success by feeding into the brain’s reward systems.
- Bryant, C.X. & Green, D. (2010). ACE Personal Trainer Manual. San Diego, CA: A B C D, 118-121, 372-373.
- Bryant, C.X. & Green, D. (2010). ACE’s Essentials of Exercise Science for Fitness Professionals. San Diego, CA: A B C D, 71-80.
- Edwards, S. (2007, Jan 16). Cardiovascular Drift. Retrieved from http://www.ptonthenet.com/articles/Cardiovascular-Drift-2789
- Edwards, S. (2007, Jun. 20). Using Heart Rate to Track Results. Retrieved from http://www.ptonthenet.com/articles/Using-Heart-Rate-to-Track-Results-2878
- Edwards, S. (2007, Oct. 15). What Your Heart Monitor is Trying to Tell You. Retrieved from http://www.ptonthenet.com/articles/What-Your-Heart-Monitor-is-Trying-to-Tell-You-2947
- Gevirtz, R.N. & Lehrer, P. (2003). Resonant Frequency Heart Rate Feedback. Biofeedback: A Practitioner’s Guide (3rd edition). New York, NY; The Guildford Press: 245-250.
- Karp, J. (2009, Mar 10) Target Heart Rate. Retrieved from http://www.ptonthenet.com/articles/Target-Heart-Rate-3187
- Sime, W. (2003) Sports Psychology Applications of Biofeedback and Neurofeedback. Biofeedback: A Practitioner’s Guide (3rd edition). New York, NY; The Guildford Press: 560-588.
- Wharton, C. (2007, Jan 20) The Client Environment. Retrieved from http://www.ptonthenet.com/articles/The-Client-Environment-2793