Enlarge your heart…

18.11.2015

At gyms across the world there is one piece of equipment you always find, and there are always plenty of them – treadmills. We run and run, both indoors and outside, hoping to improve our endurance. Do you know why working on your endurance is so incredibly good for your body though? And do you know how to increase your endurance most efficiently? I will answer these questions for you during this article.

Firstly though: What is endurance training?

Endurance is the muscles ability to perform over a certain period of time. When you work on endurance, your muscles burn energy, preferably in the form of carbohydrates and fats, using oxygen. Oxygen flow to your muscles is therefore the most important factor affecting your endurance.

If your muscle receives too little oxygen, it will lead to an accumulation of lactic acid. This causes muscles to stiffen, and forces you to stop working out. This is called anaerobic endurance. If your muscles get enough oxygen, on the other hand, it is called aerobic endurance: you keep lactic acid from piling up and are able to endure a much longer workout.

Pumping capacity

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Professor of Medicine, Jan Hoff.

What determines whether you are able to get enough oxygen to the muscles?

Your heart!

Professor of Medicine, Jan Hoff, says the whole purpose of endurance training is to increase the size and elasticity of the heart and blood vessels. This increases the maximum oxygen uptake.

“The average 20-year-old man’s pumping capacity is approximately 20 litres per minute. A top endurance athlete’s capacity, however, is twice that, equalling four kitchens taps turned on fully,” Hoff says.

“Our heart, which is the size of a fist, is a highly efficient pump,” he adds.

According to Hoff, it is only very untrained individuals who have limitation in aerobic endurance related to matters outside the body’s muscles and not the heart’s pumping capacity.

Maximum heart rate

The highest heart rate you are able to achieve is called your maximum heart rate. It is determined by heredity conditions and cannot get any higher, no matter how much you exercise. However, it does decrease slightly with age. The heart’s ability to pump blood is therefore dependent on the amount of blood that can be pumped at each heart beat, so-called stroke volume.

“Stroke volume increases when your heart becomes larger following exercise, challenges cardiac volume and becomes more elastic,” Hoff says.

Previously it was difficult to measure the heart’s stroke volume, and it was believed that full stroke volume was reached by running at an intensity of about 70 percent of maximum heart rate. This was however refuted, when research showed that stroke volume increases up to an intensity corresponding with maximum oxygen uptake. If you work at a higher intensity than this, lactic acid gathers and leads to a fall in stroke volume.

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How to exercise most effectively

Aerobic exercise is not only important if you are training to run a marathon in the shortest possible time, according to Hoff. If performed regularly, it also has a big impact on your health.

“The right type of endurance training is the most effective way to prevent lifestyle diseases such as obesity, hypertension, high cholesterol, reduced circulation and type 2 diabetes,” Hoff says.

So what is “the right” endurance training”?

Hoff, together with colleague and fellow Professor of Medicine Jan Helgerud have through their research revealed the most efficient training methods for health and endurance.

The professors say four by four-minute intervals are the best type of exercise for your body. The intervals should be performed uphill, either walking or running, outdoors or on a treadmill. You must however, combine it with strength training. Interval training is not limited to running or walking though, skiing outdoors, using a rowing machine or a bike (standing up on the pedals during intervals) are other options.

Sessions must start with a six-minute warm up at moderate intensity, followed by the four intervals. Each interval consists of four minutes at high intensity, with a three-minute active rest between each interval. In order to get the most effect out of the training, you have to be at 85 to 95 percent of your maximum heart rate at the end of the first interval, and reach the same intensity after one minute in the remaining intervals.

“You know you have reached the right level when, after two minutes, you breathe heavily, but do not experience any discomfort or stiffness in the legs,” Hoff says.

During the breaks, your heart rate should drop down to 70 percent of maximum.

“Finally, after the four intervals, you should have a five-minute cool down to finish.”

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How to find your maximum heart rate?

If you do not have a pulse watch or advanced gadgets like ear buds that register your pulse, but would like to know your maximum heart rate, keep reading!

As I said, your maximum heart rate is determined by hereditary conditions and is therefore individual. To find your maximum heart rate, you can perform a workout consisting of four four-minute intervals, and then take your pulse at the end of the last one. Add 15 strokes to the pulse to determine your maximum heart rate.

Another way of finding the right intensity is to listen to your body: When you have worked hard for four minutes, you should be able to continue for one more minute. When you have completed four intervals lasting four minutes each, you should be able to complete one more.

“If you manage to keep a conversation going during the interval, the intensity is too low,” Hoff says.

Some final inspiration: If you do this four times four-minutes interval training more than once a week, you will improve your endurance with half a percent weekly. If you do endurance exercise twice a week, you will keep your physiological age at 20 years until you are 80. So what are you waiting for?