Your heart is always pumping, although the rate at which it does so can vary dramatically. When you aren’t participating in any physical activity—for example, you’re lounging in bed—your heart slows down to its “resting” rate. As you train, one of the goals to set for yourself is to to have a low resting heart rate, ideally getting down to 50 to 70 beats or below if possible (factors like age or medication don’t allow this for everyone).
Why Athletes or Regular Exercisers Usually See Low Resting Heart Rates
When you exercise or perform any kind of general physical activity, your muscle cells require more oxygen to function well. They also need more amino acids, glucose and an “energy currency” molecule known as adenosine triphosphate (ATP). At the same time, as the muscles do work and consume nutrients, they create waste materials, such as lactic acid, that need to be removed. The circulatory system simultaneously addresses both issues, delivering what the muscles need and taking away what they don’t through the blood. Thus, as you work harder, your blood flow and volume go up.
In response to the increase in blood flow and volume that occurs with physical work, the heart adapts. More specifically, the walls of the heart thicken, and the left ventricle of the heart gets bigger. The heart thus does not have to beat as often, as it can hold and pump out more blood with every squeeze, even at rest.
Low Resting Heart Rate, Lower Risk of Cardiovascular Disease
According to Harvard Health Publications (Harvard Medical School), every time your heart beats, the resulting pulse of blood slightly increases the pressure or stress against the inside of the arterial walls. The more times your heart beats, the more often this stress is present. Additionally, your coronary arteries have less time to fill as your heart rate goes up, which can result in a discrepancy between the amount of oxygen heart cells need and the amount of oxygen the heart can provide to them. For these reasons, a reasonably low resting heart rate is associated with a decreased risk of heart disease. Some researchers theorize that a reduced heart rate may connect to cell division rates, as well, upping the chances of a longer life.
What Your Low Resting Heart Rate Means for Your Training
As your body becomes more efficient and your heart rate goes down, it likely will take you longer to get anywhere close to your maximum heart rate (MHR). Alternately, reaching your target heart rate zone might require you to up your intensity, either by going faster or by increasing your weight. If you’re working with a trainer, they should know what your resting heart rate is so they can tweak your program for you accordingly.
If you’re watching your resting heart rate well and know where it usually sits, be wary if it spikes. This symptom shows that the heart is under more stress than normal. Perhaps you are anxious about work or something at home, missed too much sleep or hit the gym one time more than you really should have. Maybe you’ve finally caught the bug people have been passing around the office. Whatever the cause, you need to give your heart a break. Drop your weight, lower your speed or take an extra rest day or two.
If you’ve been training very seriously for a long time, you might experience a phenomenon known as being “heart tired.” In essence, it becomes difficult, if not impossible, to pull your heart rate up where you’d like it to be, even when you’re working at a good intensity. Experts believe that, like unusually high heart rates, this symptom can signal overtraining and the need for recovery. Most people feel just fine as they experience this phenomenon, with their only clue being what their heart rate monitor tells them. Pay attention to your readings, and if you can’t seem to hit your targets, back off, rescheduling your tough workouts for later.