Variabilité cardiaque chez des sportifs vétérans spécialistes de la course longue distance

Résumé d’une partie de la thèse de médecine de Thomas Leti  « Intérêt de la variabilité de la fréquence cardiaque dans les dysautonomies« , Université de Grenoble, 2012.

Lien vers la thèse

Une partie de cette thèse est intitulée « SNA et activité physique chez les athlètes seniors« , page 78.

Pour moi l’intérêt de cette lecture vient de la difficulté à interpréter les données de la variabilité cardiaque. En effet ,la majorité des études sur ce sujet s’intéressent aux athlètes de haut niveau. On ne peut donc pas faire de comparaison. Le fait que les sujets de l’étude de par leur âge et leur activité, « me ressemble » (mon âge est de 52 ans et je pratique les sports dit d’endurance avec la même fréquence d’entrainement), me permet de faire des comparaisons. La première chose à faire étant de calculer une valeur de référence. Pour moi, si je remonte à 2013, je trouve une valeur de RMSSD entre 44 et 47 en étant en forme. Ce chiffre diminue à 24 avec la fatigue ! Si on prend les ondes HF, elles passent de 43 (n.u) en forme à 18 n.u avec la fatigue. Attention cependant aux comparaisons hâtives,car pour pouvoir comparer, il faut respecter les mêmes protocoles. Dans cette étude, les relevés se font la nuit alors que moi je prend les mesures le matin à jeun.

L’auteur a suivi 10 coureurs seniors (spécialistes en course longue distance) âgés de 51 ans en moyenne (+ou – 5),  s’entraînant 4.5 heures par semaine (+ou-1.8), avec 4 entraînements par semaine.

la VMA moyenne des sujets de l’étude : 16.4 (14.5 à 18.5)

Vo2max 57.3 (50.8 à 64.8)

Fc repos 53 (33 à 62)

Fc max 173 (166 à 177)

10 000 m 44’21 (39’02 à 53’19)

Les enregistrements de la FC sont nocturnes sur une nuit entière. Les sujets sont équipés d’un cardiofréquencemètre (polard RS800). Le traitement des données se fait sur une période de 30′ lors de la première phase de sommeil.

4 types de données :

Dans un premier temps, arrêt de la pratique pendant 14 jours afin de disposer d’une mesure de la VFC de référence (Nrepos)

Nent: correspond à une mesure un jour d’entrainement

Ncom: correspond à un enregistrement suite à une compétition (ici un trail de 42.5km avec 2600m de dénivelé positif)

Nrec: correspond à un enregistrement après un jour de repos

L’étude à duré 12 semaines.

Résultats:

« Le suivi de coureurs à pieds seniors nous a permis d’observer une majoration de l’activité sympathique ainsi qu’une diminution du tonus parasympathique sous l’effet de l’entrainement, et plus encore de la compétition. »

« La VFC décline avec l’âge et c’est particulièrement la composante parasympathique du SNA qui est la plus altérée, comme en témoignent les valeurs de HF. »

En effet, après 14 jours de repos, la valeur RMSSD est de 40 en moyenne et elle diminue à 35.5 après un jour d’entrainement (34.8 après un jour de repos) pour atteindre 26.5 après une compétition éprouvante.

Concernant les ondes haute Fréquence (HF) ,à partir de la valeur de référence (37.9 n.u après 14 jours de repos), on observe une baisse avec l’entrainement (32.7 Nent) et une valeur de 24 après la compétition.

Le rapport LF/HF passe lui de 2.06 (Nrepos valeur de référence) à 2.46 (Nent) à 3.86 (Ncom).

« …un mode de vie sportif aiderait à maintenir une activité parasympathique élevée,à modérer l’activité sympathique,et donc à ralentir les effets du vieillissement. »

Avec le REPOS, on observe « une augmentation globale de l’activité nerveuse parasympathique au niveau du nœud sinusal, et une activité sympathique basse. »

En plus du relevé des FC nocturne, les sujets ont répondu à des questionnaires, notamment afin de déterminer leur état de fatigue. « Certains auteurs ont suggéré que le syndrome de surentraînement aurait des causes similaires aux état de dépression.« 

Course d’orientation – Conférence de Thierry Gueorgiou

Entraînement


 Gueorgiou’s story – Part I
Posted by Jan Kocbach, 27 Nov 2007
second.jpg– One second mistake is still not good enough! This is what lies at the bottom of Thierry Gueorgiou’s orienteering philosophy – which he shared with the participants at the Norwegian O-Gala in the middle of November. Based on Gueorgiou’s two long presentations at the O-Gala, World of O presents a few short articles presenting some of the secrets behind Gueorgiou’s success. Many thanks go to Gueorgiou for sharing his presentation slides.
Perfectionist
A good illustration of the perfectionist Gueorgiou is the following short story:
– When I started running for the Finnish club Kalevan Rasti, they laughed at me when they saw my control descriptions in which I put up 1 second mistakes [see illustration to the right]. But their attitude soon turned, and they started doing the same themselves. I am not satisfied until there are only zeros along the right edge of that control description.
And as everybody can see – Gueorgiou is getting closer and closer to his “all-zeros” goal.
ogala_s.jpg
Thierry Gueorgiou at the Norwegian O-Gala. Picture: Øystein Kvaal Østerbø
PASSIONATE about O’technique
Thierry Gueorgiou’s father had an important role in Thierry’s development as an orienteer. – No training without a map, was the philosophy. Even when running on the track, the map was there. Thierry’s passion about O-technique is also mirrored in the new goal Thierry set after reaching his goal of becoming a World Champion in 2003: To become the best O’technician ever!

Thierry has increased his orienteering training from 170 hours in 1997 to 300 hours in 2007.
Following his fathers philosophy, between 40% and 50% of Thierry’s training has been orienteering since 1997 – quite impressive compared to many others in the world orienteering elite. And also a result of Thierry’s passion about O-technique.
Looking for example at the Norwegian elite, many are satisfied when they get above 20-25%. When looking a Thierry’s training, Thierry has increased his orienteering training from 170 hours in 1997 to 300 hours in 2007. Below you see the development of orienteering training compared to other training between 1997 and 2007:
opart_s.jpg
World Champion in his mind a hundred times

Over the years to come he continued becoming a World Champion in his mind.
At the World Orienteering Champs in France in 1987, Thierry’s dream of being a world champion was born – at the age of 8.
In 1991 at the spectator races of the World Orienteering Champs in Czechoslovakia, Thierry got World Champion in his mind when winning the spectator race in his age category. Over the years to come he continued becoming a World Champion in his mind – playing it before his inner mind time after time.
thierrygueorgiou_WOC2007sprintf_5_s.jpg
Until at the World Orienteering Champs in Finland in 2001: After a disappointing 18th place at the short distance in a close to mistake-free race, Thierry for the first time had to admit to himself that maybe he would not be a World Champion after all.– For the first time, I had to admit that my dream couldn’t come true, are Thierry’s words. This lead to Thierry taking his longest break from orienteering ever – a break of several months. Out of this break came Thierry’s rebirth as an orienteer: The “Full speed – no mistake” method – giving higher speed at lower risk. The “Full speed – no mistake” method will be the topic of the next article.

– For the first time, I had to admit that my dream couldn’t come true.
With this technique, Thierry regained his belief in becoming a World Champion – and the next one and a half years he won the 2003 World Championships in Trin, Switzerland over and over again in his mind. – The human brain makes no difference between reality and a mental picture. You have to feel that you are running in your garden. You have to feel that you have already run the World Orienteering Champs a hundred times, is Thierry’s attitude.

– It was “just once more becoming World Champion”.
The ultimate proof about how realistic Thierry’s mental picture of his winning the World Champs was: – When I ran into the finish as a World Champion in Trin in 2003, I was very happy – but not extremely happy. The reason: I had already seen this in my inner mind so many times before. It was “just once more becoming World Champion”.

conference thierry gueorgiou part 2

Gueorgiou’s story – Part II

Posted by Jan Kocbach, 10 Dec 2007@8:00
breakdown_s.jpg– Thierry, you are one of the best map readers I have ever seen. But if you want to become the best, you must change your way of orienteering. You have to start building much simpler mental images of the terrain if you want to become faster. This was the message from Börje Vartiainen – Kalevan Rasti’s coach – to Thierry Gueorgiou in the autumn of 2001, at a time when Gueorgiou was in his deepest valley yet as an orienteer.
WOC 2001: Breakdown of a dream
To recap from part I of this article series from Thierry Gueorgiou’s presentation at the Norwegian O-gala – Thierry’s “breakdown” was after a very disappointing 18th place at the short distance in the World Orienteering Champs in Finland in a close to mistake-free race. After many years of believing strongly that he could be the World Champion, Thierry had, for the first time, admitted to himself that maybe he would not be a World Champion after all (map example to the right –Vattula 2, WOC 2001, short distance final, Ari Anjala & Reijo Kujansuu).
– My technique is slow
Vartiainen’s message helped Thierry onto the right track. – The 2002 season was my rebirth as an orienteer, Thierry comments. A new technique, a new attitude and mental preparations were the key elements in this process.
thierrygueorgiou_WC1_2007_2_s.jpg

As an excellent map reader already at that time, Thierry read all these details accurately and fast.
So what was the problem with the old technique? Let us take a look at one of Thierry’s examples on a fantasy map (below) for an illustration of the old technique. Following along the drawn route choice, you read the map passing the marsh, then the tree root, the cliff, then between the two hills, cross the small track, then the small cliff, and so on. As an excellent map reader already at that time, Thierry read all these details accurately and fast – running in full control from feature to feature.
slow1.jpg
And the problem? Even if you run fast and orienteer fast – reading all details takes extra time.

I don’t know if this is the right way to go, but it is a fact.
Thierry: – Maps get more and more detailed. I don’t know if this is the right way to go, but it is a fact. My new orienteering technique had to account for this. Also, there are different mapping styles. Different mappers give very different maps. And there is a large range of different terrain types. I had to try to find a general method anyway.
historymap_s.jpg

16mappers_16maps.gif

maptypes_s.jpg
Upper: Mapping evolution from 1982 to 2005 in WC Final 2006 area. Middle: 16 mappers – 16 maps – animated image fromOlles.cz. Lower: Maps from different terrain types.


visible1_s.jpgVisibility
It is obvious – and most orienteers make use of it in every race: Use the most visible and distinct features as key points in your orienteering. But how far do you go in your analysis of visibility and distinctness of features? Do you analyze visibility and distinctness for all features before planning your route choice, and create a “visibility map” in your head?
Thierry [see map to the right]: – We can mark the areas from which we can see this control on the map. We can see the control from the hills, from this yellow area and from a part of the marsh.

But how far do you go in your analysis of visibility and distinctness of features?
These kinds of visibility maps are at the heart of Thierry’s new orienteering technique. Another example from Thierry’s presentation: The map below show visibility maps for two different features. The blue visibility map is for feature A, a stone in a small re-entrant. The red visibility map is for a large hill. Thierry again: – The stone you can see from only a very small area. The hill you can see from a large area.
visible2_s.jpg
Map: Ruläys, Rauno Asikainen
Distinct features

– You must identify the remarkable features.
Thierry again: – The next question I asked myself is what is important on a map. For this question, there is no general answer. This is different from terrain type to terrain type. – You must identify the remarkable features. The features which are both isolated and visible! Again – let’s use two of Thierry’s examples. The first example (to the left below) is for a special open French terrain with a lot of cliffs. As these cliffs are visible from far away, it would be tempting to base much of the orienteering on them. However, there is another set of details in this terrain type which are much more remarkable and isolated: Big characteristic trees (green ring on the map). The second example (Finnish terrain, to the right below) is very different. Here the cliffs are the remarkable and characteristic details which you can base your navigation on.
isolated.jpg
Left map: LES AUREDES, Pellegry Alain & Laurent. Right map: TAHKOVAARA, Rauno Asikainen, Jussi Silvennoinen & Börje Vartiainen
In short: Don’t use stones as a basis for your navigation in an area full of stones.

– Sometimes a contour line can be really like a motorway.
Visible and distinct features
We are nearly there – but what about all those different terrain types? – Contour details like hills and depressions are visible and distinct in many terrain types – they are usually a very good to use for this technique, is Thierry’s tip to all the Norwegian listeners at the O-gala. – Sometimes a contour line can be really like a motorway. All you have to do is to follow it, Thierry commented the second leg on this years World Orienteering Champs middle distance. Further key points in all terrain types are (1) thrust your compass and (2) keep your head high. Also – and this is the main point – when using these visible and distinct features for your navigation, you can (and must) ignore all the other details. This is what makes you fast! (But don’t narrow the technique too much, or you will end up like Thierry Gueorgiou in the World Champs middle distance in 2006 – a miserable number four…)
slow_s.jpg
“Full speed – no mistake”
Thierry: – The equation to solve is higher speed at lower risk. Piecing the above elements together, we arrive at what Thierry calls the “Full speed – no mistake” technique. Let us go back to the first example, and see how Thierry solves it with the “Full speed – no mistake” technique (map to the right). Thierry: – There is one perfect solution for every leg which you must find. The “Full speed – no mistake” technique helps you to find the optimal route choice. Runner A knows where he is – runner B knows where to go.
Let us analyze the leg and the two route choice alternatives usingvisibility maps (not shown explicitly). Along route choice alternative B, the visibility area for all three hills along the route choice is very good – so good that you can see from hill to hill, and maintaining full speed all the way. Along route choice A, you can argue that the first hill/cliff along the route choice is distinct and visible from quite a large distance.

You need to – again extremely fast – be able to visualize the terrain in 3D in your head from the physical map.
However, it is not visible from control number one, and thus lower speed and more orienteering is necessary for the first part of the leg. The next cliff you pass is again a nice, distinct feature, but visibility from the direction of the runner is rather limited. Visibility and distinctness for the rest of route choice A is also poorer than for route choice B.
See in 3D
What is needed to apply this technique effectively, is the ability to extremely fast get from the physical map to a visibility map for all distinct points in the terrain. To do this, you need to – again extremely fast – be able to visualize the terrain in 3D in your head from the physical map – as the 3D terrain model is the natural step to get from physical map to visibility map.
thierrygueorgiou_WOC2007sprintf_19_s.jpg
Master the technique
In the simple example above, this looks obvious. But let us take a look at a few of Thierry’s examples which are not that obvious. Both are from the World Cup Final in 2006 in France (Map: AYDAT, O’vert4) – a terrain which nobody masters as well as Thierry Gueorgiou.
ex2_s.jpg
Here it is not that obvious which features are distinct and visible. At first look, everything looks just the same, and it is tempting to use the round cliff just left of the line as your attack-point for the control, as it (a) looks like a distinct feature and (b) you have a good entrance to the control over the small hill between the cliff and the control.

A small error in compass bearing can be tolerated, and maximum speed can be held until close to the control.
However, when we look at visibility maps (not shown), we see that the cliff is only visible from a small area, and you might miss it if your compass bearing is not very accurate. OK you could say – “Let us take the hill just behind the round cliff. That is larger, and my compass bearing needn’t be that accurate.” But again visibility is an issue: Both the round cliff and the small hill to the right of the round cliff are “in the way”.
Let us take a look at Thierry’s approach: The hill just to the right of the control (marked with three red rings in the right part of the above figure). Due to the large flat area south of the hill, the hill is visible from a large region along the route the runner is coming from. Thus, a small error in compass bearing can be tolerated, and maximum speed can be held until close to the control.
Below you see the second example from the World Cup Final. Again, visibility and distinctness is the key – this time for the hill to the right of the leg:
ex1_s.jpg
Training and attitude

Training yourself to master the method…
The “full speed – no mistake”-technique outlined above is one thing – and in itself you might say it is nothing special. Similar ideas lie behind most elite-orienteers technique – even if it might not always be spelled out this clearly regarding visibility maps and tactics. Training yourself to master the method, having the correct attitude and – last but not least – the mental aspect, is something completely different! More about this in the next article in this series.
thierrygueorgiou_WOC2007sprintf_11_s.jpg