The Strong Heart: A Runner’s Best Friend
Figure 1. The cardiovascular system literally reaches out and touches every part of your body.9
How do you know when to push yourself to the limit on your daily running route, go for a recovery run or simply take the day off and rest? After tens of thousands of miles of running, elite runners from around the world still hire coaches and consult exercise physiologists to best answer these questions. More specifically, they seek the guidance of professionals to help them determine what type of workout they will do (lactate threshold, repeat intervals, VO2 max, etc), how long/fast it will be, and how much rest they will get. Although it would be very helpful, I suppose that you don’t have daily consultations with an endurance coach or exercise physiologist to help you decide what your training regimen should be. More than likely, you’re similar to me —not exactly world class, but take great pride in your running performance. With that being said, let’s take a look at the most commonly used method to self-monitor one’s endurance training – paying attention to your heart.
Understanding the heart and its responses to exercise stimuli is one key that you ought not overlook. Much of the change within the human body that takes place during endurance exercise is cardiovascular-related. Because of the close relationship between the heart and the rest of the body’s physiological systems, the varied means of monitoring the heart are quite accessible and useful for the serious runner.
The Traditional Approach: %HRmax
When working out, The American Heart Association advises individuals to monitor their workout intensity while training via % maximum heart rate (%HRmax)1. The most commonly used formula for finding HRmax is:
HRmax = (220 – age in years)
Thus, a 30-year old athlete would have an expected HRmax of 190 beats per minute (bpm).
190 HRmax = (220 – 30)
Using this basic formula, athletes of the 20th century have had a guide for exercising according to heart rate zones, which are helpful in determining at what intensity to exercise at according to %HRmax . The following zones are commonly used in endurance training6:
- Recovery Zone: 60-70 %HRmax
- Aerobic Endurance Training Zone: 70-75 %HRmax
- Anaerobic (Lactate Threshold) Zone: 80-90%HRmax
- VO2 Max Zone: 95-100%HRmax
These heart rate training zones are multiplied by your HRmax to find the target heart rate for a specific workout. However, coaches and athletes alike have not found it very accurate to rely upon the HRmax formula of (220 – age in years) due to the variability across individuals5. Furthermore, as pointed out by Gerald Savorsky, HRmax is largely unaffected by training8. Thus, as individuals get fitter, it becomes harder to get accurate feedback using this measurement; therefore, other approaches are needed to provide a better option for well-trained athletes.
The advent of heart rate monitors with advanced features has revolutionized the face of exercise monitoring and feedback. Below, I’ll explain these developments that many, including myself, believe have paved a more reliable and insightful way to guide workout frequency and intensity.
Better Approaches
Dr. Juha Karvonen, a renowned Finnish exercise physiologist, developed a measure called heart rate reserve (), or the gap between your resting heart and your HRmax6. He cites other studies (Roitman et al.7) which demonstrate that using the traditional approach, %HRmax, may not accurately predict a heart rate high enough for moderate to highly trained athletes to exercise at in order to achieve maximum benefits.
Many endurance athletes and coaches agree with Dr. Karvonen that is a more accurate method to determine target heart rates5. Karvonen’s formula has the benefit of accounting for resting heart rate, which is adjusted as your fitness increases. A stronger heart has a higher stroke volume, thereby reducing the number of beats per minute (bpm). Let’s take a look at a well-trained athlete who knows his true HRmax and uses the formula to find his target heart rate for a lactate threshold run.
A 25-year old athlete has a HRmax of 180 bpm and resting heart rate of 40 bpm.
would be:
180 – 40 = 140 bpm
Thus, if this athlete wants to run a lactate threshold run at 86%, this is multiplied by and then added back to the resting heart rate.
(.86 * 140) + 40 = 160 bpm
This is quite a difference from using (220 – age) and exercising at 86% of the assumed HRmax, which would lead this athlete to hit 168 bpm in the same workout.
Heart Rate Variability… the Way of the Future?
Figure 2. of Heart. The R wave of the heart beat occurs when you see a large vertical upward spike in the line. Per heart beat, you have 1 spike. Thus, in the picture above, you see 2 successive heart beats.The distance between 2 R-waves is considered the R-R interval.10
While Karvonen’s development of provided a more accurate guide to help determine exercise intensity than % HRmax, arguments have been that a potentially more accurate training tool may still exist – heart rate variability (). This method has been shown to be a helpful guide to optimize workout intensity and to prevent overtraining3. is the measurement of the time between R-R waves on an echocardiogram () graph2. See Figure 2. Incomplete recovery from an intense workout affects the parameters of readings. Thus, unlike %HRmax, takes into account daily changes in your heart rate which are believed to reflect how well your body recovered from the previous day(s) workout. measurements gives athletes practical insight into whether their body is prepared for another high-intensity workout or whether they’d benefit more from a recovery run. In a study completed in 2007, Kiviniemi et al tackled the question of if could be used to maximize the benefits of individualized training programs3.
Their study consisted of 26 moderately trained male recreational runners, mean age 31-35 +/- 8 years, who had a body mass index less than 28, didn’t smoke, weren’t competing, and were free of cardiovascular diseases. Runners were split into the following 3 groups:
- A control group of 9 men
- A training group () of 8 men who used a pre-defined training routine
- A -guided group () of 9 men.
The control group did not exercise during the 4-week training period. subjects repeated a cycle of low intensity exercise on day 1, high intensity on days 2 and 3, and rest on day 4. subjects used a Polar S810i heart rate monitor to test their each morning, which then determined their training for the day. They performed a high-intensity session if there was an increase or no change in ; if their was lower than a set threshold or lower for two consecutive days, a low-intensity session or rest was prescribed, with every 9th day off regardless of . All runs were performed outdoors unless inclement weather warranted the use of a treadmill.
Final analysis showed that both the and groups had trained an average of 6 days/week at 66% HRmax for low-intensity sessions and 80% HRmax for high-intensity sessions. Subjective feelings of fatigue were similar as was the total distance run/week.
Peak oxygen consumption (VO2max) did not markedly increase in the group, but VO2max increased in the group. Though both groups saw an increase in maximal running velocity, -guided training resulted in a larger increase in maximal running speed (.5 +/- .4 vs. .9 +/- .2 km/h). The group also recorded an increase in running velocity at ventilatory threshold, or the point at which oxygen consumption peaks.
This study concurs with others showing that maximal running speed can be increased without an increase in VO2PEAK, but the group’s increase in VO2PEAK was probably due to better periodization and timing of high-intensity sessions. Analysis showed that the group actually had one less intense session/week than the group (3 vs. 4). In conclusion, this study demonstrated that measurements can be used to effectively guide endurance-training routines.
The Bottom Line
This is what we all want, right—well-guided, individualized training that takes into account the changes in our bodies throughout a training program? While there’s simply no substitute for hard work, if I can use available technology to gain better results than my opponents in similar training, I’m going to do so. I’m not a high-tech guy by many standards, but I have found that recording certain training markers and what my training regimen looked like before a big PR has been helpful. With the advent of heart rate monitors and associated computer software that mimics laboratory monitoring and tests, I’d say that tools like the Polar S810i and other monitors in that class have the potential to help you optimize your training, available time, and race efforts. If you use to help guide your next training cycle, there’s a good chance that you’ll show up at the starting line well-rested, yet trained to the best of your ability.
I have no affiliation with, nor have I received any compensation from Polar Electro, Inc. or any other heart rate monitor company.
References:
1 American Heart Association. Target heart rate. http://www.americanheart.org/presenter.jhtml?identifier=3030999. Accessed Oct. 4, 2008.
2 Institute of HeartMath. Heart Rate Variability, Mental Stress, Emotional Stress. http://www.heartmath.org/research/research-home/heart-rate-variability.html. Accessed Oct. 10, 2010.
3 Kiviniemi, et al. (2007) Endurance training guided individually by daily heart rate variability measurements. European Journal of Applied Physiology. 101:743–751.
4 Paavolainen L, Häkkinen K, Hämäläinen I, Nummela A, Rusko H (1999) Explosive-strength training improves 5-km running time by improving running economy and muscle power. Journal of Applied Physiology. 86 (5):1527–1533
5 Wilmore, I.H. & Costill, D.L. (1988) Training for Sport and Activity: The Physiological Basis of the Conditioning Process. Champaign, IL: Human Kinetics.
6 Karp, Jason M. Heart Rate Training for Improved Running Performance. http://www.coachr.org/heart_rate_training_for_improved.htm. Accessed Oct. 31, 2010.
7 Roitman J, Pavlisko JJ, Schulz GW. Exercise Prescription by Heart Rate and Methods. Physician and Sports Medicine (1978). 6: 98-102.
8 Savorsky, Gerald M. Evidence and Possible Mechanisms of Altered Maximum Heart Rate With Endurance Training and Tapering. Sports Medicine (2000) Jan. 29 (1): 13-26
9 Image created by . Accessed November 1st 2010 from:http://commons.wikimedia.org/wiki/File:Circulatory_System_en.png
10 Image created by en:User:Nunh-huh. This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. Image obtained November 1st 2010 from: http://commons.wikimedia.org/wiki/File:EKG2.png