Exercise physiology

Your heart is your most important muscle and is vital for your well being. Your heart is all the time delivering oxygen to the muscles. When exerting the muscles are working harder and need more oxygen and the heart is working faster to supply the increased need of oxygen. A valuable tool to make training as effective as possible is to measure heart rate intensity. The work intensity is directly proportionate to both heart rate and oxygen consumption. This relation makes it possible to use heart rate as a valuable tool to reflect work intensity and work load.

The heart rate is measured in beats/minutes. The heart rate intensity is the relation between current heart rate and your maximum heart rate, presented as percentage of maximum heart rate. Most exercise physiologist use this value only, some are also takes the resting heart rate into account using other formulas (such as Karvonen formula). Important is to use one formula from time to time.

Studies show that different work intensities have different metabolic effects. Continuous heart rate monitoring is found to have a positive physiological effect where direct feedback during exercise can increase motivation. Heart rate feedback during exercise has also been seen to educate participants about how the body works and how to train in the best way to reach certain results. It’s important to know that the heart rate can vary to some degree from day to day depending on different temperatures, level of hydration, if there is an initial illness etc.

Using the Activio Intensity Meter, it’s easy to see how you are working through the different zones. You can easily see how fast your heart rate is increasing and set specific targets in the zones. How fast your heart rate is decreasing after a work session is an indication of your fitness level. Normally the faster you recover the better is your fitness level if you have done the same amount of work at the different occasions over a period of time. Important to know is if you have worked with a high perceived exertion and with much accumulated lactic acid in the muscles, then it can take more time for the heart rate to decrease as the heart rate will remain higher due to the deficit and the increased need of oxygen for the muscles.

When training it is important to find the right intensity levels depending on what you want to achieve with your training, i.e. Increase your heart's and respiratory capacity, effectively increase your metabolism or improve muscle strength. Regardless of what your aims are, heart rate based training can help to improve training for everyone. Below we explain some of the basic heart rate training concepts.

Maximum heart rate

The maximum heart rate expresses the maximum amount of heart beats that the heart is capable of beating per minute. The maximum heart rate can be specific for a certain kind of activity depending on what you are used to. The limitation to reach the maximum heart rate can be in the muscular strength and stamina or depending on the technical ability to perform a maximal work. For example a biker will more likely reach the maximum heart rate easier on a bike than when running, whereas it can be opposite for a runner.

Important to know is that the maximum heart rate is individual for a person and has nothing to do with your current fitness level. There is no formula from where you can accurately calculate the maximum heart rate. Individual variances can be very high for any formula used. The maximum heart rate is decreasing with age, as a general rule with one beat per year, however if you have been active during your life the maximum heart rate tends to remain at higher levels.

Working heart rate

This is the heart rate you have during exercise. The working heart rate varies depending on the actual exercise performed and length of the session, how hard you are exerting and your current fitness level.

Resting heart rate

The resting heart rate expresses your lowest heart rate when you are at complete rest. A lowered resting heart rate normally indicates that your fitness level has improved. The resting heart rate is normally measured in the morning when you are laying down.

Aerobic threshold heart rate

The aerobic threshold heart rate level is where the body is producing more lactic acid than your metabolism allows to reduce during exercise. The response is that the muscles’ capacity is affected and it will become difficult to remain the work load as a result. The threshold is difficult to define. For most normally trained individuals the level is between 80-90% of maximum heart rate. For less trained the threshold can be lower. For very well trained the threshold can be even higher, top cyclists have been seen to have just a few beats difference between aerobic threshold level and maximum heart rate. This means they will be able to perform at a very high level of maximum over a long period of time.

Training at and above the aerobic threshold level, you will accustom the body to deal with increased amounts of lactic acid and you will improve your aerobic capacity. Important though is to take into account that training with aim to improve aerobic capacity will require longer periods of rest between training sessions to allow the body to recover.

Oxygen consumption

The oxygen consumption is the amount of oxygen uptake for the body expressed as liter per minute. Maximal aerobic effect is the highest volume of oxygen uptake during exercise (VO2 max). The maximal volume is dependent on how effective the muscles are to consume the oxygen available. The capacity to utilize oxygen improves with training, therefore better trained individuals normally have a higher VO2 max than less trained.

Generally expressed, when the work intensity exceeds the level for maximal oxygen consumption level, the metabolism changes from aerobic to anaerobic energy processes where oxygen is not used to produce energy, and where the rest product is lactic acid among other substances.

Energy production

Aerobic and anaerobic training are two different processes where energy is produced during exercise. Knowledge about the different processes is vital to be able to plan and make training as effective as possible. The energy during training comes from carbohydrates, fat and proteins. At low intensity training a higher amount of energy comes from the fat resources. At higher intensities an increased amount of energy comes from carbohydrates. The total amount of energy (calories) consumed are always higher on higher intensity level of aerobic work. The high intensity training will also increase the ”after burn” and energy needed to recover and ”repair” after training. It is important to find the right balance between high intensity training sessions and the right amount of recovery that is needed in between sessions to allow the fitness level to improve over time.