Day two concluded with all eyes on the men's and women's 50km walk races, with organisers nervously monitoring the progress of athletes chasing medals in sweltering conditions.

The walks took place 24 hours after a casualty-filled women's marathon, where 28 of 68 starters failed to finish.

However, despite steamy conditions on Qatar's waterfront course, the two races largely passed off without the sort of scenes that dogged the marathon, where several exhausted athletes were taken away from the course on stretchers.

The men's race was won by Yusuke Suzuki, who became the first Japanese athlete to win the 50km men's race.

Read: Jabir, Dutee crash out of Championships

Suzuki's pillar was almost outshone by Portugal's silver medallist Joao Vieira who at 43 became the oldest male athlete to win a medal at the world championships. Canada's Evan Dunfee took bronze.

The women's race saw a Chinese 1-2 with Liang Rui taking gold in 4hr 23min 26sec and Li Maocuo the silver.

Italy's Eleonora Giorgi took the bronze -- defending champion Ines Henriques failed to finish.

The IAAF's decision to award the championships to Doha came under renewed scrutiny following the marathon carnage, with French decathlon world champion Kevin Mayer adding his voice to the criticism on Saturday.

"Clearly by organising the championship here, they (the IAAF) didn't put the athletes first, they've mostly put them in jeopardy," said Mayer.

"Even if people aren't saying it out loud, it's obvious it's a catastrophe."