17 July 2013

Less fatigue after TDG's 200 miles than UTMB's 100 miles

It is not all running races which have a scientific article published about it. I read with great interest the recent article from Grégoire P. Millet’s group at Institute of Sport Sciences at University of Lausanne in Switzerland where they have studied a group of runners in Tor des Géants (TDG). The lead author is Jonas Saugy and the article entitled “Alterations of Neuromuscular Function after the World’s Most Challenging Mountain Ultra-Marathon” is published in PLoS ONE 2013; 8: e65596. The article gained great interest in media when it came out a couple of weeks ago and it has been referred to in for instance Science, Runner’s World and National Geographic.

In the study, 25 male runners took part and of them 15 (60%) completed TDG. These runners were compared with a control group of 8 healthy males who did not run but experienced a similar level of sleep deprivation during the race. The results were also compared with those in a similar study conducted by Millet’s group at UTBM (Millet GY et al. Neuromuscular consequences of an extreme mountain ultra-marathon. PLoS ONE 2011; 6: e17059).

Not surprisingly, maximal voluntary contraction (MVC), central activation ratio (CAR) in both knee extensors (KE) and plantar flexors (PF) became statistically significantly reduced during TDG. Markers of neuromuscular fatigue (NMF) such as 100 Hz doublet (PS100) and peak twitch measured by electromyography (EMG) were also altered in TDG runners, but not in sleep derived controls. Blood concentrations of creatine kinase (CK), lactate dehydrogenease (LDH), C-Reactive Protein (CRP) and myoglobin were also higher during and after TDG in runners, but no elevation was seen in sleep derived controls. So far the findings were as expected, but, surprisingly, the degree of neuromuscular fatigue, muscle damage and inflammation was less in TDG runners compared with UTMB runners. Sauguy and colleagues speculate that this might be due to an anticipatory pacing strategy during the first part of the race and fatigue combined with a high level of sleep deprivation during the second part of the race leading to a slower speed during the whole course. The speed decrease relative to UTMB in the TDG runners tested was -23.1% (5.5±2.8 vs 7.2±1.3 km/h average equivalent-flat speed considering TDG to have an equivalent flat distance of 545 km and UTMB 262 km). Paradoxically, an extreme ultramarathon such as TDG thus seems to induce relative muscle preservation. So, from a pure muscle perspective it might be more exerting to run shorter than longer. When I completed La Boucle at Trail Verbier St Bernard last summer I talked to some UTMB completers who said that the faster pace and elevation change over a shorter distance made this race almost tougher supporting this notion. This weekend Emelie Forsberg completed the 65 km Ice Trail Tarentaise Val d´Isère Skyrunning Event and wrote on her Swedish blog that this was the toughest course she had run despite the relatively short distance. It will be interesting to see what I say in September after hopefully having completed TDG.

No comments:

Post a Comment