Heart rate and training: the variables to be considered

Every workout produces both physiological and structural changes in the body. Some are visible to the eye, others cannot be seen, but are probably the most important. The cardiovascular workouts will modify the structure of the heart by increasing the volume of the left ventricle, allowing the heart to circulate the same amount of blood, but using fewer beats per minute.

Until a few years ago, only a few people could afford the luxury of training using their heart rate, now that tools such as heart rate monitors are affordable for everyone, it is impossible not to consider one of the most important parameters for training: heart rate.

Heart rate variables

On average, the heart beats 60-80 times per minute, it may seem little, but making a quick calculation will turn out that in a single day become 86,400-115,200 beats. This huge amount of work devoted to the heart muscle has a strong correlation with health and can be influenced by many factors: lifestyle, sport, nutrition, etc.

It should be specified, however, that the heart rate in beats per minute (BPM) may have important differences from one person to another because of:

• Sex: In women the heart rate tends to be higher.
• Age: Heart rate is proportional to age.
• Health: the higher the general health of the body, the lower the beats per minute.
• Training status: the heart rate is inversely proportional to the training status.

Even in the short term, changes in heart rate may occur due to several factors, including:

• Hydration status
• Mood
• Body temperature
• Humidity
• Recovery: understood both between the various training series and between one training and the next.

Beat monitoring

It is therefore necessary to constantly and rationally monitor heart rate, because a workout that brings the beats below the required threshold will not produce any effect, the opposite could even be detrimental to recovery and long-term performance. While everyone knows the maximum heart rate (HRmax).

It should be noted that there are other important values that may be essential to keep under control, including:

• Resting heart rate (HRrest): measured by a heart rate monitor in the morning before getting up. It should be measured for at least 3 mornings in a row and then averaged.
• Heart rate at the aerobic threshold: equal to 70-80% of HRmax, it represents the intensity at which there is a greater production of lactate compared to the basal values. Pre-, post- and during exercise heart rate, useful to quantify the work done.
• Heart rate at anaerobic threshold: fundamental because it is a reference point for calculating other heart rates, such as long background, short background, etc. It is the point of intensity corresponding to the maximum concentration of lactate that can still be disposed of by the body, creating a situation of balance between its production and removal. It is often classified as 4mmol/L concentration, since it should then be individualized but almost indicative.

Anaerobic threshold can be estimated quite reliably with the Conconi test, which compares the increase in work intensity (expressed in watts or in km/h) with the increase in BPM.

The Conconi test can be easily performed on a treadmill, where the heartbeats will be related to the running speed. In untrained people, you start from a basic speed of 4-5 km/h and increase by 0.5 every 30". The same test performed by more trained people can start from 6-7 Km/h and increase by 1km/h every 30".

The data must be entered in a graph that will have the BPM on the X axis and the Km/h on the Y axis. In order to have reliable data, at least 10 pairs of speed/BPM values are necessary before arriving at the curve deflection that indicates the anaerobic threshold.

Estimating heart rate: Cooper's test, and all (more or less) reliable formulas

Anche se la Frequenza Cardiaca massima è ben nota a tutti, è indispensabile fare un piccolo approfondimento, esistono infatti molti metodi per poterla stimare, le formule più note sono quelle di Cooper e Tanaka:

 

Cooper HR_max= 220 – age

Tanaka HR_max= 208 – (0.7 x age)

Both formulas consider only one of the parameters that can influence heart rate in the long term (age) while neglecting all the others.

Ball State University proposes a formula that includes gender in its calculation:

_HRmax Men= 214 – 0.8 x age

HR_max Women= 209 – 0.7 x age

The most accurate formula that considers certain subjective parameters is Karvonen's, also known as the Cardiac Reserve Frequency:

HRreserve = HR_max - HRrest

From here you can calculate your training heart rate in this way:

Training heart rate = % of HR_max to be achieved (HR_max - HRrest) + HRrest

There are dozens of such formulas, but none of them are completely reliable. Errors of even a few bpm off maximum heart rate can cause an anaerobic threshold training session to be performed beyond the required intensities, making all the work done ineffective.

The only way to calculate your heart rate is by means of maximum laboratory tests that should be repeated for three days in a row, taking as good the highest figure.

HRmax does not vary over time

It should be noted that HRmax is a value that is stable over time and does not vary according to the degree of training. It is therefore useful to calculate it if you want to decide at what percentage of work to train, but it is not an adequate parameter to determine the quality of training. There are two ways to do this:

• Heart rate at rest: The lower the resting heart rate, the greater the range compared to the HRmax on which you can work, allowing you to use higher intensities for a longer time, or to train at the same intensity with less fatigue.

• Objectification of training data: It is necessary to have your own training program at hand in which to record the subjective sensations experienced during each session (a session rate of perceived exertion (RPE)), but also in the different exercises or phases of training. Then create a training diary in which your perception of fatigue on a scale of 1-10, for example, will be marked.

Take your pre-workout heart rate, during the central phase or at the main moments you want to analyze and 3 and 6 minutes after the training session ends.

If the training has been structured and performed correctly, you will see the beats per minute drop in the post-exercise measurements, you will also see that with the same heartbeats detected during the training you will feel less fatigue perceived, or that the same fatigue will be felt at higher beats.

Normally we talk about the advantages that you can have following a certain type of training or using certain equipment, in this case the emphasis is different: training based on your heartbeats does not only bring advantages in terms of both health and performance, is the only way to ensure that your training produces the results for which you are doing it.

A professional athlete needs to train within certain ranges because he/ she must work within precise parameters to ensure that his/ her body creates certain physiological processes, in the same way a person with hypertension will have to control his/ her beats throughout the training to avoid negative repercussions in terms of health, a person who wants to do a type of activity within the so-called "fat-burning zone" will have a very narrow range of beats to be respected, beyond which will not consume the largest proportion of fatty acids possible.

• Malik M. - Taskforce of European Society of Cardiology and the North American Society of Pacing and Electrophysiology: heart rate variability, standards of measurement, physiological interpretation and clinical use.
• All About Heart Rate (Pulse). American Heart Association. 22 Aug 2017. Retrieved 25 Jan 2018.