Translation of the French sports magazine Sports & Vie N° 32

 

 

Véronique Billat is University Professor at Evry Val d'Essonne. She divides her time between her researches in the LEPHE laboratory (Laboratory for the study of exercise physiology), and the coaching of top athletes among whom can be mentioned the 5000m Kenyan runner, Isabella Ochichi who won the silver medal at the Athens Olympic Games. Prior to this, Véronique Billat was an accomplished tri-athlete and member of the French University cross-country skiing team (from 1980-1982) and of the French University Cross-Country running team (from 1980-1984).

 

 

If one had to award a particular distinction to the person who intervened the largest number of times in Sports & Vie, Véronique Billat would surely be in the run-up. One must say that she combines several qualities which justify that we often appeal to her expertise: she knows the matter, she knows the terrain and she knows sport. We also know each other very well and have done so for a long time now, our first encounter dates back to 1984. At that time she was finishing her physiology studies in Grenoble. For my part, I was starting studies in sports journalism after having done a Bachelor's Degree in physical education at ULB (Université Libre de Bruxelles). We had many things in common and this complicity weaved the framework of a long standing relationship spangled with numerous articles like the one we have chosen to reproduce below and which reviewed in 2005 the said "scientific" progress in training. Over the years, this collaboration also lent to amusing scenes. The last one goes back to a visit in our office on a Wednesday afternoon, which coincided with the arrival of a kid from the district who took advantage of the quite ambiance to come and do his homework. As he was not very bright in Math’s and Physics, it was also an occasion for him to have these explained to him. That day he was having trouble with formulas such as A² - B² or (A+B) ². We were all quite busy and it was Véronique who took things in hand to try and make him understand what the remarkable identities had of remarkable. Pour fellow! No doubt he had no knowledge that he was receiving a private lesson that day, from one of the most eminent university professors of France. One would like to write that after this lesson, illumination happened and that he is currently following a brilliant academic career. But this would be somewhat far from the truth! The last we heard from him was that he had become a clown!

 

 

Moser has broken the Law Tables.

 

Francesco Moser was trained by Professor Francesco Conconi, who, in a very media way, hence demonstrated the power of science.

 

The heart rate meters appeared in the stores in the middle of the 1980’s. Finally, isn’t it this technological finding that was at the origin of what we rather pompously called “Scientific Training”?

 

No, I do not believe so. Scientific training starts with the definition of the effort zones which correspond to the use of the different metabolisms, aerobic and anaerobic. Researchers identified intensities which coincided with physiological mechanisms such as the accumulation of lactic acid or the carrying away of the respiratory mechanisms. Repairs were then put opposite these intensities and thus the observation of the heart rate found all its purpose.

 

Can we date this more or less completely?

 

Scientifically, it is necessary to retain 1979 with the description of the lactic threshold by Mader. From the media point of view, it would be Francesco Moser’s hour record in 1984. The Italian runner was trained by Francesco Conconi, Professor of Physiology at the University of Ferrare, who, in a very media way, hence demonstrated the power of science.

 

At what point did this affect the way to train?

 

Let us say that it has not fundamentally changed the contents of the sessions.

Since the 1920’s “interval training” or “tempo training” was done, according to the choice of length of effort. At the beginning of the 20th century for example, the Finnish runner, Hannes Kolehmainen, trained at the speed of the records he wished to beat by progressively increasing the time of effort. The idea of a variation in the running speed was already present in the minds. The big difference was that from then on, we knew how to associate these recommendations to physiology concepts.

 

In your opinion, what does the future hold for us?

 

I believe that we are at the dawn of big turnovers. In the 1980’s we defined in broad outlines, a series of stages during effort. Little by little we discover with more precision what indeed happens during these different stages with the result that we are here today to define six basic speeds each endowed with precise characteristics. This begins with the one which corresponds to the maximum use of lipids. It is a question of a very light effort at about 40-45% of VO² max. Then, we distinguish where the speed or the oxidation of the glucids gets the upper hand over those of the fats which occur at approximately 55% of VO²max.

 

For the first two speeds, we thus base ourselves on the energy nature of the substrata?

 

Exactly, and in a general way, the intensity in which arise these changes hardly evolves with the training. Then, things get more complicated. We talk of speed threshold for the one we will be able to maintain during two or three hours of effort without exhaustion. At this point, we already breathe a little faster.

This increase of the ventilation aims at maintaining the carbon dioxide pressure in the blood at the rest level. The first ventilation threshold 1 is situated around 60% of VO²max. If we increase the pace, we arrive at a second ventilation threshold. This time it is a question of eliminating the CO² which forms in mass in the tissues. At this stage we find it difficult to speak. We are at about 80% of VO² max. Then, one can distinguish a specific speed which corresponds to a maximum of systolic ejection; which means the quantity of blood that the heart’s left ventricle is capable of pumping at each contraction. The occurrence of this specific speed varies according to the athletic level of each person. This happens between 60 and 95% of VO² max. A little faster yet and we get to the speed which corresponds to the maximum oxygen consumption. Thus, we find ourselves at 100% of VO² max. Finally, we describe two more very fast paces; the one which we can hold for about one minute and which corresponds to the maximum oxygen deficit (+/-130% of VO² max) and the top speed at maximum anaerobic capacity (up to 180% of VO² max).

 

All this gives the impression of progressing during effort as if we were climbing stairs…

 

Not quite, as things are not as stable as we can imagine. With time, the movement degrades and the energy expenditure increases, which means for example that we can reach the maximum oxygen consumption (VO² max) at a lesser speed than the one determined in the laboratory. We speak of “Slow constituent of adjustment of VO² max”, or sometimes of “critical speed” for the one enabling to reach VO² max after six minutes of effort. We are here

in direct drive with current-day science.

 

We are far from the popularized programs where it was recommended to train within precise ranges of heart rate!

 

 

When we speak of elite athletes, the cardio-frequency metre is not enough to lead training in a rigorous way. In the future, we will surely be able to improve it.

But personally, I always believed that it was more worthwhile for amateur athletes who, thanks to this instrument, better understand the idea of association between the intensity of effort and the elevation of the metabolism.

By understanding and being interested in the functions of ones own body, one has better access to the notions of aerobic and anaerobic and oxygen consumption etc.

 

The use of the cardio-frequency metre also entails certain risks. Many people badly interpret Astrand’s equation (220-age) and are convinced that they would put themselves in great danger if they passed this fateful number.

 

This is why I rather recommend using Karvonen’s equation: HR max = 210-age x 0.65. This is fairer, especially after 30 years. These sportsmen must also understand that is not bad to have a heart that beats faster. This reflects a dynamic heart. One must just be careful that the pulse does not race when for example one climbs at more than 220 beats/minute. This could hide a real problem. The use of the cardio metre could sometimes enable sportsmen to detect a problem such as a heart rhythm disorder, which would otherwise never have been seen, and which can easily be handled by a cardiologist.

 

Over the years, many other tools have been added to the monitoring of the heart rate. In your opinion, which are the most useful?

 

It is necessary to sort things. For example, certain brands propose data on ventilation which result in a simple calculation on the base of the heart rate. I have tested their validity in the laboratory. I had a margin of error of 40%! In short, it is not worth much. On the other hand, I know that some firms are working on new technologies which will allow taking into account the respiratory frequency. In order to do this, we can proceed in different ways: either by putting an elastic band at the level of the cardio-frequency metre’s thoracic belt. Either by putting a little sensor in the nostril to measure the air flow and reflux. One must be aware that the work of the respiratory muscles represent up to 20% of the energy spent.

 

Do you have anything else to say?

 

We could measure the oxygen blood saturation by means of these little clips that we place on the fingertip or on the ear lobe. This would enable to diagnose some desaturation phenomenons which occur particularly at high altitude in athletes who are very high-performing in endurance. In summary, these people unconsciously limit their ventilation to reduce the energetic cost. But at the same time induce the fall of oxygen blood content. It could be a good idea to watch this parameter also.

 

(PHOTO d’aviron: One must be aware that the work of the respiratory muscles represent up to 20% of the energy spent.)

 

Would it make sense to monitor ones temperature?

 

Yes, there is a very close relation between the heart rate and the temperature. When one gets dehydrated, the blood volume decreases. In case of over heating, the distribution also privileges the periphery to allow the blood to cool down. The heart accelerates and the blood pressure rises to avoid the dismantling of the cardiac pump. In an event such as the marathon, one cannot analyse a frequency curve without also thinking about the temperature.

 

Finally, all the training theories are based on the fact that the heart rate faithfully translates the blood flow variations in the body. But we forget the other determining factor of this parameter: the stroke volume!

 

Exactly, and yet there is a tight link between the size of the heart, its strength of contraction and its frequency. Whilst the heart beats very fast, the filling phase is very brief and we are then limited in the quantity of blood that we will be able to eject during the contraction. Some very high performing athletes react then by reducing their heart rate while it is at its maximum in order to maintain an important debit thanks to a better stroke volume. Nowadays, we have realised that this stage corresponds to the well-known Conconi threshold, which is, what we took to be a sign of exhaustion constitutes in fact a very subtle adaptation of the body.

 

In a general way, how does the stroke volume of a home-body and that of the sportsman differ, and how do they evolve during effort?

 

In the home-body, this volume represents approximately 60 millilitres, in other words, half a pot of yoghurt. During effort, this doubles: 120 for 60. In the sportsman, we double the data again: 120ml at rest and up to 250 during effort, the equivalent of a small bottle of coca cola.

 

Can we measure it?

 

The technique does exist. To this effect we use a measuring tool by impedance very similar to the one that is used to measure the percentage of fat in an individual. In summary, we determine the flux variations on the basis of the electrical resistance of the body tissues. The company Polar is in fact preparing a solution inserted in the form of a jacket in which this technology would be added: cardio frequency metre, impedance, temperature, saturation, stroke volume and measurement of the heart variability. This will enable to proceed to a number of cross-references between these different values. For example, we will be able to follow the progress in the connection between the heart rate and the speed of the runner thanks to an accelerometer in his shoe.

We have an index called “cardiac economy” which answers somewhat to the question “How many heart beats to run how many metres?” This conveys in a way the quality of the training. However, we notice that this fluctuates enormously according to the days. On the basis of these indications, we would know which sessions would be worth pushing to the full and which are the ones where we should not force too much in order not to accumulate unnecessary tiredness.

 

(ARTICLE EN MAUVE) page 47

 

The end justifies the means

 

During the last few years the Laboratory in Evry has published many articles on the set up of a pattern on the aerobic metabolism during short endurance tests. It has come out of this research that the aerobic and anaerobic metabolisms are more interwoven than we previously thought.

Thus, the implementation of the aerobic system depends a lot on the request of the anaerobic system at the beginning of the effort and this relation lasts all along in so far as the athlete spontaneously adopts a speed which will allow him/her to preserve an anaerobic "reserve" for the final sprint. In an 800 or 1500 meter race, for example, the first two thirds are run at the greatest speed which enables to solicit the least in the anaerobic reserves. This is a way to keep as much under the feet, before releasing the horses for the third left of the race. Véronique Billat deducts that this anaerobic reserve constituted the limiting factor, as well as the parameter of the performance control, that is an athletic declension of the ancient proverb: the end justifies the means.

(ARTICLE EN MAUVE “LA BARRE DES OUTILS” PAGE 46)

 

EVOLUTION OF SPORTS INSTRUMENTS

 

The arrival on the market of the first heart frequency metres in the early 1980’s has somewhat jostled the sports training habits. Before them, we did not really have a means of monitoring the effort intensity. The device had success and was widely respected until we noticed the limits of the performance. Thus, the heart rate does not tell us much about the body’s adaptation to high levels of effort. For thirty years, we have thus tried to refine the approach by analysing for example, the variability or the RR interval, which is supposed to reflect the stress undergone by the cardiovascular system. At the same time, we were also interested in the relation between the heart rate and the speed, which was possible thanks to the integration in the functions of the receptors such as the pedometer, the accelerometer or the GPS. In cycling, the problem is slightly different. The relation speed-power is of the hyperbolic type and not linear as in running races. We prefer to think according to power. Devices enable to measure it in a precise way directly from the pedal or from the back hub of the bike. They were quite expensive at first so were only used by the professional cyclists (at least the ones interested in it). But prices are getting lower over the years and these captors are now accessible to almost all purses.

Heart rate, distance, speed, power. This is becoming quite complete. And other effort parameters interest many researchers such as oxygen saturation and haemoglobin which we can pick up thanks to portable captors fixed at the end of the finger. The same thing goes for the heart rate which we can estimate thanks to the measure of the electric impedance. It must be known that at full speed, the heart no longer has the time to fill up in full before emptying. This decrease in the stroke volume explains the separation in the relation between the heart rate and the blood flow for intense efforts. At present, there remains

to find a way to analyse the respiratory frequency. Perhaps an elastic belt fitted with detectors to record the thoracic movements. Thanks to it, we could deduce the intensity of the ventilation work. And the buckle is fastened.