Athletes often wonder about their ideal resting heart rate (RHR). For a good reason—they usually run a lower resting pulse or heart rate than average individuals.
As people exercise more, their heart (being the pump) compensates for this extra demand by pumping harder. As exercise becomes routine and this need to pump greater amounts of blood intensifies, the heart undergoes molecular changes to adapt.
Similarly, when the athlete is resting, this fine-tuned heart that is used to pumping large amounts of blood, no longer needs that high of an output and it slows down. This is the mechanism why athletes run a lower resting heart rate, largely by conditioning.
Your resting heart rate can tell you a lot about your cardiovascular health in most cases. Provided of course, you are not taking any medications that can affect this—these include beta blockers or certain calcium channel blockers that reduce the heart rate in patients.
In general, a lower resting heart rate indicates a better cardiovascular health profile. And it is easy to measure: a pulse can be measured simply by checking the impulse about 1 inch below the wrist line. This can be felt using your index or the middle finger of the opposite hand.
Once the pulse is felt, it should be measured for at least 30 seconds –doubling this can get you the minute heart rate. For example, if you measure 35 beats in 30 seconds, your resting heart rate is about 70 beats/min.
There is significant variability in the normal resting heart rate within individuals, including that seen in men and women. Body frame, exercise status, cardiovascular health and sex, all can affect resting heart rate.
The ideal heart rate or a normal pulse is between 60-100 beats per minute with an average of 70-75 beats/minute. A heart rate above 100/min is described as a tachycardia and below 60/min is called bradycardia. Despite this wide range, athletes always aim for a lower resting heart rate between 50-60 beats/min. As this RHR is slower than normal, it is called sinus bradycardia and results from conditioning or exercise and is not of any concern in athletes.
Women, and those particularly with a smaller body frame have a slightly higher resting heart rate. Again, regular exercise can reduce this significantly indicating a better cardiovascular profile.
In athletes, it is not. Some athletes regularly have a resting heart rate in the 40s. As long as they feel well and do not have symptoms, a lower resting heart rate is not concerning.
When a lower resting heart rate is accompanied by symptoms such as dizziness, low blood pressure, irregular rhythm, palpitations (racing heart), shortness of breath or chest pain, then the equation changes. These individuals must seek immediate medical evaluation for potential underlying cardiac problems.
A higher resting heart rate has been linked to poorer cardiovascular tolerance and a higher incidence of cardiovascular events and mortality in a study done in 2013 that followed almost 3000 individuals for 16 years.
Importantly, this study showed that independent of physical fitness, a higher resting heart rate was an independent risk factor for worsening cardiovascular outcomes.
Although studies have shown an association between lower RHR and improved cardiovascular tolerance, it is to be emphasized that in healthy individuals, simply reducing heart rate artificially or by means of medications would not be expected to improve outcomes. Rather, the focus should be on cardiovascular conditioning by means of regular exercise.
Simple exercises that can reduce resting heart rate include:
The key in these cases is that the exercise regimen should be undertaken on a regular and consistent basis over a long period of time (at least 6 -12 months) to eventually see the results.
Endurance training is designed to push limits and often consists of 4-5 hours or more of intense workout in different phases. This is typically designed to prepare an athlete to run an Ironman or Ultra-marathon, a grueling activity that spans over an entire day. The stress on the heart in these extreme sports is not negligible and neither is the day-to-day training that athletes undertake in order to be ready for it.
But all of that extreme training does raise an important question: is endurance training to this extent bad for your heart?
Some scientists believe that abnormally high endurance training can cause structural changes in the heart in the heart and put some individuals at risk for sudden cardiac events.
A study published in 2008 showed that endurance athletes who engaged in extreme exercise regimens had lower resting heart rates but also had a higher incidence of rhythm disorders in later stages of their lives.
The molecular basis for this finding was that the heavy endurance training led to a drop in the level of a “pacemaker” protein called HCN4 in the heart’s sinoatrial node—the site that determines the rhythm. Structurally, this led to an abnormal electrical conduction system in the heart that may explain the basis of some rhythm disorders seen in this group.
Also, an enlargement of some of the chambers of the heart (particularly of the right side that receives the blood) and fibrosis of the cardiac muscle have been seen in endurance athletes likely from a repetitive high output injury state.
This is the focus on some studies recently. Hydration can help sustain blood volume during athletic training and improves performance. Electrolytes such as potassium and magnesium have also been utilized in a clinical setting to reduce the risk of arrhythmias, but not necessarily in those who exercise.
MAGNAK® Endurance Mix, an electrolyte rich hydration formula was designed specifically to help endurance athletes train harder while minimizing muscle cramping. Studies are clearly needed to assess if this electrolyte formula can reduce maximal heart rate during high intensity training as well as its impact on the resting heart rate. This may pave the way for long term studies in athletes to assess if regular supplementation with this can help reduce cardiac remodeling and structural effects seen in some these endurance athletes.
Resting heart rate can indicate a lot about fitness and a lower RHR is preferable in healthy adults who can condition themselves with a regular exercise regimen. However, heavy endurance training for a long time can lead to changes in the heart that may not be beneficial as these athletes grow older.
Experts however believe that the benefits of exercising still outweigh the risks and moderate exercise should be a prescription to a healthy life.
