In running, your heart rate can vary from workout to workout, depending on the intensity of your run, of course, but also other factors. What are they ?
- The type of exercise
- heat and humidity
- Hydration
- altitude
- Energy levels
You feel the rays of the sun on your skin. Your feet pound the asphalt as you climb to your favorite vantage point over the city. You only hear the birds chirping. And your heartbeat. Quick.
Faster than usual, in fact. You glance at your heart rate monitor. Your heart rate is 8 beats per minute higher than usual.
” What ? That’s normal, right? Yes, that’s perfectly normal. By tracking your heart rate during exercise over a long period of time, you will notice that it changes from one training session to the next. The route that seemed easy to you yesterday may suddenly feel like someone has set your world to a 2% incline.
The intensity of your training and your current aerobic threshold influence your heart rate, but the following five factors can also explain variations in your heart rate during a ride.
1. THE TYPE OF EXERCISE (BAH YES!)
Heart rate varies in different activities because you use different muscles and train at different intensity levels.
An obstacle course, for example, uses large muscle groups and will not require the same effort as a series in the gym to develop the biceps brachii.
Running typically yields the highest maximum heart rate in a resistance test , whereas for the same event this maximum rate may be 10–15 beats lower in cycling or rowing.
2. HEAT AND HUMIDITY
Your heart rate generally increases with heat and humidity. In fact, your heart rate will gradually increase throughout your run, even if your pace doesn’t change.
Your body tries to cool itself down during exercise, and it most often does this by sweating. Humidity reduces the efficiency of perspiration, and your body temperature then increases, along with your heart rate.
If it’s hot, but not humid, like on a typical Sunday desert ride, your heart rate will still be elevated due to the extra work the heart has to do to help cool your body.
Under these conditions, your heart rate may be 5 to 10 beats higher than normal. But don’t panic: you can use your heart rate along with perceived exertion and subjective feelings to set an appropriate pace.
3. HYDRATION
We need water. Lots of water.
You know this, of course, but we tend to quickly forget the three essential things to do to stay hydrated: drink, drink and drink.
If you are not properly hydrated, your heart rate can increase because your blood volume decreases and your body lacks the fluids it needs to maintain its temperature.
And it’s not just in the desert that you can get dehydrated. Dehydration can occur in both cold and hot environments.
If you notice your heart rate increasing with no change in pace or other variables, consider drinking accordingly.
4. ALTITUDE
If climbing Mount Everest isn’t for everyone, it’s for good reason. For several good reasons, even, but today we’re going to focus on lower air pressure aloft.
When atmospheric pressure is lower, there is less pressure to get oxygen into your lungs. Less pressure means your heart has to work harder to deliver enough oxygen to your working muscles. And again, your heart rate increases while your pace stays the same.
Fortunately, it only takes a maximum of two weeks for your body to adapt to high altitude. If you’re just visiting the Alps, you’ll need to slow down to keep your heart rate in the right range. And before setting off to conquer the mountain trails, remember that it takes longer to recover from intense effort at altitude.
So train hard and rest more!
5. ENERGY LEVELS
Your body gets its energy from three sources: carbohydrates, fats and proteins.
As exercise intensity increases, you burn proportionally more carbs and less fat (protein metabolism is still quite limited). And even at low intensity, you still need some carbs to burn fat.
But what does all this have to do with your heart rate?
If you go for a ride without a good level of carbohydrates, you will have a hard time maintaining your rhythm at a given heart rate. Your perceived exertion and your subjective sensations will increase. In other words, you’ll probably end up swearing to yourself never to run again. Never again. And at that time, your heart rate will decrease.
This is called food cravings, and you can counter it by eating carbohydrate-rich foods. As a general rule, always pack some form of unmanageable energy on any outing lasting more than two hours.
