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528 Chama, N.E., Albuquerque, NM 87108 http://www.cbass.com |
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Heart Rate: What it Means Carol and I have been comparing resting heart rates for years. (Hers is lower.) But it wasn’t until my brother-in-law gave me a Fitbit for Christmas that I have been able to track my heart rate 24 hours a day—and come to appreciate how much it reveals about fitness and health. We’ll start with some basics and then move on to lesser known and more complex factors. Resting Heart Rate A resting heart rate between 50 and 100 is considered normal, but most healthy people are between 60 and 80. Above 100 is considered a rapid pulse, called tachycardia; an unusually slow resting heart rate is called bradycardia (bray-dee-KAR-dee-uh). Fitbit calculates average resting heart rate by measuring heart rate when it detects sleep, and by measuring it throughout the day while you are awake but inactive (no movement detected). Your heart rate is faster when you get excited or angry or if you are in pain or have a fever. On the other hand, resting heart rate slows during sleep and tends to be lower if you are very fit. Between 40 and 50 during sleep is not unusual. What is too slow may depend on your age and level of fitness. When symptomatic, it may cause fatigue, weakness, dizziness, sweating, and at very low rates, fainting. It is well-known that resting heart rate of well-trained individuals is 40-60 beats per minute. That’s because a trained heart is stronger and able to move more blood with each contraction. Maximum Heart Rate This is where things begin to get complex. We are told that the simplest way to compute your maximum heart rate is to subtract your age from 220. That you should expect your maximum heart rate to drop with each birthday. For example, if you are 50, your maximum heart rate is 220 minus 50, 170. I know firsthand that maximum heart rate doesn’t have to drop every year. I stopped using the formula when I discovered that my heart rate was not falling with age. The standard formula doesn't work for everyone. My experience is that maximum heart rate won’t slow down if you don’t. My maximum heart rate was first measured at Lovelace Foundation for Medical Education and Research in Albuquerque when I was 39 years old. My max was 180 beats per minute. That was the last time the standard formula worked for me. Measured repeatedly at the Cooper Clinic, my heart rate maximum hovered around 180 over the next 32 years. The high on the treadmill was 190 in 1992 (age 55) and the low on the exercise bike 173 in 2007 (age 69).
This photo was
taken by Bill Reynolds at the end of my second stress test at Lovelace
Medical Center. It makes a difference where heart rate is measured. Standing on a treadmill is likely to produce a high maximum than sitting on a bike or rower. My latest reading, on the Schwinn Airdyne, was 166, still 25 beats above that predicted for my age (220 minus 79 is 141). While modality, protocol, and motivation make a difference, I believe it’s fair to say that my example shows that the standard formula doesn’t work for those who continue to challenge their limits. For the back story on the standard formula, see my FAQ: http://www.cbass.com/FAQ3.htm#Forget We are also told to use the formula to determine your optimum training zone. That a 50-year-old should multiply 170 by 0.6 (for the low end) and by 0.8 (for the high end), which gives a range of 102 to 136. Your heart rate should fall between these two numbers to build aerobic capacity—that is your ability to deliver oxygen to the body’s cells during exercise. Even if your heart rate does fall as predicted, I question the training zone concept. My belief is that all-out training is the most efficient way to build aerobic capacity. Under the “size principle,” muscle fibers are activated in order of size; you can’t activate the large, strength fibers without activating the small, endurance fibers. High-intensity training stimulates growth in both the strength and the endurance elements, while training in the target zone stimulates growth mainly in the endurance elements. For more details: http://www.cbass.com/ResistanceMitochondrial.htm See also my FAQ on the “Black Hole of Exercise,” which says if you want to be your best, go hard and go easy; don't focus on the middle: http://www.cbass.com/FAQ(11).htm (scroll down). (If you are in poor condition, have heart disease or other medical problems you should, of course, consult your physician before undertaking any kind of training program.) Recovery after Exercise The stress ECG, which is a part of each visit to the Cooper Clinic, records my heart rate at 1, 3, 5, 7, and 10 minutes following peak exertion. I focused on maximum heart rate and paid little attention to these recovery numbers—until a very fit friend told me that the number he watches after each interval sprint is heart rate recovery. He learned from his cardiologist that this is an important factor in stress tests. I’ve been ignoring a very important heart rate variable. The speed at which your heart rate recovers is a key measure of fitness. The more fit you are, the faster the recovery. The first minute after exercise is the most important. Your heart rate should fall 20 beats or more and continue dropping rapidly for several more minutes. A drop of more than 20 BPM is a sign of a strong heart. Your pulse may remain elevated for 24 hours or longer after a high-intensity workout. The reason for this is that all-out exercise stimulates both an aerobic and anaerobic response. This causes a release of growth hormone and testosterone as well as an increase in protein synthesis. (See intensity-testosterone connection below) On the down side, the Cleveland Clinic Foundation reported in the October, 1999, New England Journal of Medicine that a heart rate drop of 12 beats or less in the first minute after exercise is abnormal—and “a powerful predictor of overall mortality.” During a six year follow-up period, 56 percent of participants who died had an abnormal rate of recovery compared to only 3 percent with normal recovery. Heart Rate and Health Resting heart rate is a measure of health as well as fitness. Writing in the Harvard Health Blog on June 17, 2016, Executive Editor Matthew Solan called RHR “one of the easiest, and maybe most effective, ways to gauge your health.” In general, a slower resting heart rate is better, because a faster rate puts more stress on your heart and blood vessels. “In fact,” the UC Berkley Wellness Letter told readers, “studies have consistently linked faster resting heat rates with increased risk of heart disease and death from all causes, independent of fitness level and other cardiovascular risk factors such as high blood pressure, high cholesterol, and being overweight.” A 2013 study in the journal Heart concluded that “elevated RHR is a risk factor for mortality independent of physical fitness, leisure-time physical activity and other major cardiovascular risk factors.” If your resting heart rate is over 80, you should talk to your doctor about your overall health—and ways to bring your heart rate down. If you aren’t exercising, now would probably be a good time to start. My Numbers Checking my Fitbit after my morning walk has become a regular part of my day. I’ve found it to be an excellent motivator—causing me to be more mindful of the need for sleep and more consistent with my daily recovery walks. I’ve also learned a lot about the daily rhythm of my heart. (Carol’s RHR is still lower than mine.) My average resting heart rate varies from 60 to 54, depending on how active I am, usually higher on workout days. I’m now averaging slightly over eight hours of sleep a night, with my heart rate dropping as low as 40 during the night. My last Cooper Clinic stress test was done using my usual Airdyne high-intensity interval workout, which calls for 3 30 second all-out sprints, with 90 seconds recovery. While the test results show that my heart rate peaked at 166 after one sprint and 153 after another, it’s not clear to me which was the last hard 30 seconds. With that qualification, my heart rate recovered to 129 at 1 minute and 102 at 3 minutes. Either way my recovery shows a strong heart. Fitbit also shows heart rate recovery. For example, it charts heart rate during our Sunday foothill hikes. Our trek as this is being written was a scenic—and telling—version of the standard Cooper Clinic treadmill protocol, times two. A steady buildup to maximum effort. Starting at our front door, we went down a drainage channel and up and around the mountain above our subdivision—and then up the side of the mountain. It was a steady climb of about 14 minutes, ending with a dash of about one minute up the side of the mountain. We turned around at that point and came down the mountain, and then continued on our way. The second part of the hike, up a long sandy channel and then a shorter hilly area, also ended in a steep climb lasting about a minute. We turned around at that point and headed home. Total time was 53 minutes. Fitbit showed my heart rate peaking at 166 at the top of the first climb, and recovering to 138 at one minute and 119 at two minutes. On the second climb my heart rate peaked at 185 and recovered to 155 at one minute, and 130 at 2 minutes. In the not so good category, Fitbit shows that I’m still having the mystery spikes in heart rate demonstrated during my last visit to the Cooper Clinic. This usually happens during my recovery walks. If it wasn’t for Fitbit I wouldn’t know it was happening. I don’t feel anything. No stress, nothing to suggest an elevated heart rate. I just came back from a 17 minute recovery walk of 1,772 steps, including a long up hill stretch--and no heart rate spike. A similar walk yesterday produced the same result, no spike. Two days ago, however, the same walk as today (going in the opposite direction) produced a spike to 173 BPM lasting several minutes. There seems to be no rhyme or reason to it. All three walks felt about the same. Dr. McFarlin called the spiking benign and nothing to worry about as long as I don’t feel any discomfort—no chest pain, lightheadedness or fatigue. My heart apparently continues to work normally, pumping blood throughout my body. See http://www.cbass.com/CooperClinic29years.html I’m going back to the Cooper Clinic in a few weeks, and hope to learn more about the spikes and my heart. * * * Testosterone-Intensity Connection My testosterone reading during my last Cooper Clinic exam was the highest ever at 666. I believe that my age-resistant testosterone readings are the product of regular high-intensity exercise. Release of growth hormone and testosterone as well as an increase in protein synthesis following high-intensity exercise appears to support this view. April 1, 2018 Comment on this article: FEEDBACK Ripped Enterprises, P.O. Box 51236, Albuquerque, New Mexico 87181-1236 Home | Products Index | Ripped Bks | Lean Adv. 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