Health concerns Le Tour de France 2013

As Le Tour de France soars over the highest elevation etaps in the next few days -monday is rest day-, the main question- doping or not – arises daily.

Watching Le Tour day-by-day makes regular people think that there must be some superman performance in the background of this miracle “mountain climbing”.  Those interested in cycling could, see the most exciting stages of this year’s tour like today and from Thursday until Friday . Let’s look behind the curtians of the Cycling Circus.

We know professional cyclists have strong legs and the desire to win but what role does food and drink play in their chances of success?

The Tour de France is considered one of the world’s most demanding events of physical endurance. In its 100th edition, this year’s Le Tour – currently underway – encompasses 21 stages, totalling 3479km, including six mountain stages with climbs as high as 2000m.

We can expect cyclist speeds and stage times nearly identical to last year’s event, which featured 20 stages plus a prologue time trial, over 3497km.

The time taken to complete individual stages ranged from 51 minutes and 24 seconds (stage nine: a flat time trial over 38km, with a mean speed of 48.4 kilometres per hour) to five hours, 42 minutes and 46 seconds (stage 12: a medium mountain-stage over 226km, with a mean speed of 39.5km/h) with an overall mean race-pace of 39.9km/h.

Given such speed and consistency of pace, it probably seems obvious that hydration and nutrition are crucial.

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Hydration is the first priority for competitors in any prolonged endurance event. Sweat rates vary between individuals and depend greatly on the workload (heat produced by muscle contraction) and climatic conditions (temperature, humidity, air passage over the body) but are probably about one-to-two litres an hour for most Tour cyclists.

Excessive fluid loss can lead to a loss of power, so it’s recommended that any athlete engaged in vigorous exercise minimises fluid losses to no more than 2-3 per cent of body mass during exercise; electrolytes (such as sodium and potassium) are also lost in the sweat and should be replaced if sweating is heavy and exercise prolonged. But here’s where things get a bit tricky.

In a sport where a one per cent change in performance could be the difference between wearing the coveted yellow jersey and second place, fluid over-replenishment may also equate to carrying unnecessary weight. A 70kg rider who has lost two litres of sweat (about 3 per cent of body mass) has less mass to push uphill.

So that rider’s performance should be better on climbs, as long as his power output is not compromised by the mild dehydration. Only with long hours of testing can a Tour rider determine their own optimal balance between hydration, body-mass and power output.

Consuming a sufficient amount of dietary carbohydrates before, during and after exercise is also crucial. We store carbohydrates predominantly as muscle and liver glycogen, and a tiny amount as blood glucose. These are the key fuels for muscle contraction during intense exercise: glycogen depletion below a critical threshold will result in a dramatic decline in performance (known in cycling as “bonking” or “hitting the wall”).

Carbohydrate loading can super-compensate glycogen to beyond normal levels, thus minimising the chances of bonking.

Consuming carbohydrates during exercise can also reduce the rate of glycogen decline, enabling an athlete to maintain a given exercise intensity for longer before the onset of fatigue.

Although sports drinks are one practical way of delivering fluid, electrolytes and carbohydrates (simple sugars such as glucose and fructose, and complex carbohydrates such as maltodextrin), a rider could do similar with water, jam sandwiches and a banana.

To support optimum performance over the three-week Tour, riders also need to consume enough daily energy to offset their high expenditures, and adequate dietary protein to support muscle recovery.

Negative energy balance (such as when the total daily energy from food and drink is less than that expended) or inadequate dietary protein can lead to metabolic changes and cannibalism of existing body proteins to produce additional energy for cells.

It sounds worse than it is, but those changes may impair exercise performance. Tour riders attempt to minimise the risk of impairment by consuming as many kilojoules (kJ) of energy as they expend.

Which raises the obvious next question: how much energy does a Tour de France riders actually expend, and what do they eat and drink?

Well before the advent of sports nutrition, riders competing in early Tour editions were pretty much left to their own devices to complete each stage, which included foraging for themselves along the way to satisfy their hunger and thirst.

Times have changed although, surprisingly, there is very little published data on the dietary practices of modern-era Tour de France riders.

Research has shown cyclists may voluntary dehydrate by more than 2% during prolonged stage racing, which would theoretically improve uphill cycling ability.

Assuming the same 74kg cyclist can still maintain 450W, such dehydration would result in an increase of 0.12W/kg. But it should be noted that dehydration, especially beyond 2-4%, can significantly increase thermal strain and influence exercise capacity. source: http://health.thewest.com.au/news/753/fuelling-the-tour-de-france-cyclists-for-peak-performance

This – “measuring the watt power the cyclist generates” – takes us to an interesting debate:

Frenchman Antoine Vayer, who was a coach at Festina when the infamous EPO scandal broke in 1998, says it is possible to know who is cheating by measuring how much power a rider generates. Vayer insists that a performance is “miraculous” if a rider goes beyond the 430-watt threshold, and “inhuman” beyond 450 watts.

And let’s see what Vayer pointed out in connection with this years’, first real mountain climb étap, where  englsihmen Chris Froome won.

The first calculations made from Chris Froome’s ascent to Ax-3-Domaines in his Tour de France stage eight win on Saturday shows that the Team Sky rider generated about 433 watts – the third best performance of all time on that climb.

It seems that unhuman like performances already stirring debates at this year’s Tour, and the best is juts to come.

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