SINGAPORE - It has been a week since runners Yong Yuen Cheng, 43, and Lim Nghee Huat, 61, embarked on what they called "the most challenging run of their lives". They aim to run 50km for 50 days in a row to celebrate Singapore's 50th birthday and pay tribute to its founding fathers and pioneers. Staff and students at ITE are taking turns to run with Mr Yong and Mr Lim; other seasoned marathoners have joined them on some days.

Here's a look at the picturesque scenery along their routes, the people they meet and behind-the-scene preparations to help them cope with the physical demands of their daily 50km run.

DAY 1 - Ultra-marathon runners Lim Nghee Huat (in green) and Yong Yuen Cheng starting the first of their SG50 special runs on April 16 to celebrate Singapore's 50th birthday and pay tribute to its founding fathers and pioneers. They will run at least seven routes through places such as MacRitchie Reservoir Park, East Coast Park and Labrador Park.

DAY 1 - Students from Beacon Primary School cheering on as ultramarathoners Mr Lim Nghee Huat (in green), a Chinese television editor at MediaCorp and Mr Yong Yuen Cheng (in white), a teacher at Hwa Chong Institution, ran past the school on Day 1 of their Go50 Run feat.

DAY 2 - Support staff Maureen Setyadi (right) using sprinklers to spray water at Mr Yong Yuen Cheng to cool him down while he drinks iced isotonic drink. Both runners say the most challenging part of their Go50 Run feat would be battling the heat, especially after 10.30am. April is typically the warmest month in the year for hot and humid Singapore.

DAY 2 - Both men wear special ultramarathon gear that deflects radiated heat. Sunburn has not been an issue, as their support crew would spray water at them and pass them wet sponges and wet towels to help them stay cool. They also apply sunblock liberally.

DAY 2 - Mrs Deborah Lim feeding her husband Lim Nghee Huat some watermelon cubes during his 50km run. Mrs Lim is an ever-present figure at Mr Lim's races, attending to his every need. She prepares iced energy drinks, suns the wet shoes he changes out of, and even prays for cloud cover during hot weather.

DAY 3 - Mr Yong Yuen Cheng (left) offering fellow ultramarathoner Lim Nghee Huat (seated) a drink after finishing their 50km run on the third day. They were accompanied by 20 runners from the Safra Running Club, including 37-year-old designer Koh Hui Ping (blue visor). Ms Koh led the pack for most of the way as she paced the runners in a route covering West Coast Park and Lower Delta Road. Ms Koh, a seasoned runner, came in second in a recent Nanjing Mountain Marathon.

DAY 3: The ultramarathoners taking photographers with a group of runners from the Safra Running Club, who have joined them on the third day of their quest to run 50km daily for 50 consecutive days. Mr Lim Nghee Huat (seated) sustained a minor knee injury on Day 3 after he tripped and fell on a roadside kerb during the route that took them from West Coast Park to places like Queenstown, Bukit Merah and Pandan Gardens.

DAY 4: It was an early start for Mr Lim Nghee Huat (first from right) and Mr Yong Yuen Cheng (second from right) on the fourth day of their 2,500km quest. They started at 7am, an hour earlier than usual, to beat the heat. Sunday's route took them along Singapore's eastern coastline, a popular trail among marathoners.

DAY 5: The run through Upper Peirce Reservoir is challenging in that it is hilly but it is more shady and cooler. It is also a runner-friendly route with fewer kerbs and traffic lights, which would help Mr Lim recover from his knee injury. The organising committee had planned to run a route starting at MacRitchie Reservoir and running through Choa Chu Kang and Jurong, but changed plans due to the hot weather. The runners are guided by Aetos Auxiliary Police throughout their runs to ensure their safety on the roads.

DAY 5: Mrs Deborah Lim (in blue), 56, and volunteer Ms Maureen Setyadi (centre), 36, preparing various isotonic drinks and energy gels at the back of the supply car. The vehicle follows the runners throughout the course. Both men also snack on carbohydrate-rich fruits like banana, papaya and honeydew.

DAY 5: Mr Yong Yuen Cheng (extreme left) and fellow ultramarathoner Lim Nghee Huat (second from right) are seen in action with supporters at Upper Pierce Reservoir on April 20. Singaporeans can pledge a run in solidarity with the runners at www.go50.sg. They are, however, not encouraged to join the runners in person due to safety concerns.

DAY 5: Ardent supporter and runner Gerrard Lin (second from right) and ITE College West teacher David Ho (third from right, in white) helping to massage ultramarathoner Lim Nghee Huat (in green) as he takes a short break from the 50km run at Upper Pierce Reservoir.

DAY 5: It is a scenic run through Upper Pierce Reservoir, a cooler route which they would take again on Day 6 and Day 7. The runners consume carbohydrate-rich foods such as bread and roti prata from nearby Casuarina Curry restaurant.

Click here to read more stories and get regular updates on the runners' progress.