Ultra-marathon through the Alps

Competitors run through the Mont-Blanc massif in the Alps during the 16th Ultra-Trail du Mont-Blanc (UTMB) race in Chamonix, France, September 1, 2018. The race is a 106-mile (170-km) round trip foot race through the Alps, starting and ending in...more

Xavier Thevenard of France runs in the Col de Voza near Chamonix, France, August 31, 2018. The race is open to 2,300 runners, who are given a maximum of 46 hours and 30 minutes to complete the course. Thevenard, who won the UTMB, finished it in 20...more

Competitors climb at La Balme near Chamonix, France, August 31, 2018. Picture taken with a long exposure. REUTERS/Denis Balibouse

Competitors warm up by a fire at Lake Combale near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Jim Walmsley of the U.S., compatriot Zach Miller and Kilian Jornet of Spain run in the Col de Voza near Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

Competitors climb the Val Ferret near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Luzia Buehler of Switzerland waits for the start in Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

Competitors rest in Dolonne near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Competitors climb at La Balme near Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

A competitor rests in Dolonne near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Xavier Thevenard of France celebrates after winning the 16th Ultra-Trail du Mont-Blanc (UTMB) race in Chamonix, France September 1, 2018. REUTERS/Denis Balibouse

Competitors run at Lake Combale near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Jim Walmsley of the U.S. runs in the Col de Voza near Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

Competitors run at Lake Combale near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Competitors climb the Val Ferret near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

Kilian Jornet of Spain runs in the Col de Voza near Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

Contestants wait wait for the start of the race in Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

Competitors run in the Col de Voza near Chamonix, France August 31, 2018. REUTERS/Denis Balibouse

A competitor crosses a stream at the Val Ferret near Courmayeur, Italy September 1, 2018. REUTERS/Denis Balibouse

A contestant lights a candle in the St-Michel church before the start of the race in Chamonix, France August 31, 2018. REUTERS/Denis Balibouse