Alterations of Neuromuscular Function after the World’s Most Challenging Mountain Ultra-Marathon

We investigated the physiological consequences of the most challenging mountain ultra-marathon (MUM) in the world: a 330-km trail run with 24000 m of positive and negative elevation change. Neuromuscular fatigue (NMF) was assessed before (Pre-), during (Mid-) and after (Post-) the MUM in experienced ultra-marathon runners (n = 15; finish time = 122.43 hours 617.21 hours) and in Pre- and Post- in a control group with a similar level of sleep deprivation (n = 8). Blood markers of muscle inflammation and damage were analyzed at Pre- and Post-. Mean 6 SD maximal voluntary contraction force declined significantly at Mid- (213617 % and 210616%, P,0.05 for knee extensor, KE, and plantar flexor muscles, PF, respectively), and further decreased at Post- (224613 % and 226619%, P,0.01) with alteration of the central activation ratio (224624 % and 228634 % between Pre- and Post-, P,0.05) in runners whereas these parameters did not change in the control group. Peripheral NMF markers such as 100 Hz doublet (KE: 218618 % and PF: 220615%, P,0.01) and peak twitch (KE: 233612%, P,0.001 and PF: 219614%, P,0.01) were also altered in runners but not in controls. Post-MUM blood concentrations of creatine kinase (371963045 Ul?1), lactate dehydrogenase (11456511 UI?L21), C-Reactive Protein (13.167.5 mg?L21) and myoglobin (449.36338.2 mg?L21) were higher (P,0.001) than at Pre- in runners but not in controls. Our findings revealed less neuromuscular fatigue, muscle damage and inflammation than in shorter MUMs. In conclusion, paradoxically, such extreme exercise seems to induce a relative muscle preservation process due likely to a protectiv