To improve your performance, it’s important that you estimate the right level of cardio intensity first. If, for example, you want to engage in long slow distance (LSD) endurance training, it’s important that you know exactly how fast or slow you need to run to achieve the desired effect.
Very calm workouts stimulate fat burning in your body. However, if you run too fast during this workout, it will mainly be your sugars that are burned to provide energy.
The level of intensity of your running exercises can be expressed in a number of ways. This may range from vague to highly detailed: slow, extensive, jogging, recovery run, fartlek (also known as ‘speed play’) and intensive.
You can also express this intensity in numbers, for example: 80% of your maximum speed or one kilometre in 5 minutes. The more closely the intensity of your running exercises and your training goal match each other, the more effective your workouts will be.
Heart rate as a measurement of fitness
One highly efficient way to determine the intensity of your workouts is to record your heart rate during exercise. Your heart rate conveys essential information about the intensity of your workouts, as well as about your fitness levels (stamina).
Your heart rate increases in a linear fashion, in line with the intensity of your efforts. A comparison of the different heart rates measured at the same pace at different times will give you an idea of your fitness level. Once you start getting fitter, you’ll find that your heart rate will be lower when exercising at the same level of intensity. If you find that you can run faster at the same heart rate, this means your workouts have had positive results. You will also notice your fitness level has improved if your heart rate is lower after exercising.
How do you calculate your maximum heart rate?
You can calculate your heart rate based on specific percentages of your maximum heart rate. The most accurate way to check this maximum heart rate frequency is by taking a professional running test, although there are other ways to find out as well. If you go running regularly, are an athlete and are physically fit, you can determine your maximum heart rate by running at full intensity for approximately one minute – after doing warm-up exercises for at least 10 to 15 minutes, where you switch up your pace at the end.
If you don’t exercise regularly, you can also calculate your maximum heart rate by using the rule of thumb, ‘220 minus your age’. If you’re 30 years old, then, you can assume your maximum heart rate is around 190 beats per minute.
Note that this formula is somewhat flawed, as the maximum heart rate is not a reflection of your level of fitness and does not change with your training achievements. Do bear in mind, however, that you cannot, or can no longer, calculate your maximum heart rate when you’re tired. There is also the fact that your maximum heart rate (i.e. aerobic capacity) decreases with age.
As noted, you can calculate your training heart rate based on specific percentages of your maximum heart rate. However, this does depend on the type of exercise involved:
- Recovery run: -70%
- Slow endurance running (long slow distance, LSD): 70-75%
- Controlled/paced endurance running (extensive long-distance running): 76-80%
- Intensive long-distance running: 81-85%
- Tempo runs (anaerobic threshold running): 86-90%
- Fast interval run: 91-95%
- Resistance training: +95%
The advantage of this method is that it’s easy to apply, while a disadvantage is that it does not provide options for building your stamina and boosting endurance. Regardless of your fitness level, your training heart rates will remain unchanged, as your maximum heart rate does not change with training.
The Karvonen Formula
If you do want to consider your fitness level while exercising, you’re better off using the Karvonen Formula, a mathematical formula to measure your aerobic training heart rate range. In calculating your training intensity, this formula factors in your resting heart rate (resting HF) in addition to your maximum heart rate (maximum HF).
%(maximum HF – resting HF) + resting HF = HF during exercise
For example: your morning pulse rate is 50 and your maximum heart rate is 200. You want to train at 70% of your maximum intensity. In this case, your training heart rate is calculated as follows: 0.7 x (200-50)+50 = 155
Based on the Karvonen Formula, your training heart rate for the various types of training will be as follows:
- Recovery run: -65%
- Slow endurance running (LSD): 66-72%
- Paced/controlled long-distance running (extensive long-distance running): 73-76%
- Intensive long-distance running: 77-84%
- Tempo runs (anaerobic threshold running): 85-90%
- Fast interval run: 91-94%
- Resistance training: +94%
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