On Thursday evenings, Ms Chris Hortin-Tan, who has only 5 per cent of her central vision in both eyes, usually dons a running singlet, shorts and track shoes.

At the Singapore Sports Hub, the visually impaired housewife trains with a guide, each holding onto a long tether. The guide alerts her to obstacles and steers her in the correct direction.

Ms Hortin-Tan is preparing for the Spartan Sentosa Sprint next month. It is an obstacle course race which is more than 5km long and features more than 20 obstacles.

She is among some Singaporeans with disabilities who are not letting their condition stop them from taking part in marathons and other physically demanding sporting events.

The 44-year-old, who is married with two teenage sons, says: "I want to challenge myself to conquer all the obstacles. I want to show my boys that it is important to try in life and not to give up."

Despite having lost most of her sight to glaucoma at the age of 14, she has remained active over the years and started taking part in marathons and other physically challenging activities in recent years.

She ran her first full marathon - the Standard Chartered Singapore Marathon - in 2014 and has since taken part in other events too.

To prepare for them, she trains regularly with Runninghour, an inclusive running club which provides support for special needs runners and aims to integrate them into mainstream society.

The group, which has more than 400 members, consists of "buddy runners" who might be physically, visually or intellectually challenged, as well as able-bodied fitness enthusiasts who volunteer as running guides.

Every Thursday and Saturday, the group either goes for a run or does circuit training to build strength and stamina.

Its members have taken part in marathons, triathlons and other events.

For example, buddy runner Wong Ren Yi, 26, ran a half-marathon at the 2016 Standard Chartered Singapore Marathon.

The car mechanic, who had graduated from a special needs school, says: "Running the half-marathon is not difficult if you train for it.

"I think taking part in such activities is a good way to keep fit, lose weight and make friends."

This year, at least three buddy members will take part in the Spartan Sentosa Sprint event.

The race's business development and community outreach manager, Ms Meagan Douglas, 42, says: "We don't track who is disabled unless specific groups identity themselves.

"Unless a particular athlete or team requests for special assistance, we do not differentiate between able and disabled racers."

All participants who complete the race are awarded the same finisher T-shirt and medal, she adds, and almost anyone with any disability can take part.

However, she cautions that some obstacles can be particularly challenging for people with disabilities.

Those with limited lower body mobility may find obstacles involving climbing walls and carrying loads particularly tough, she adds.

But that is not stopping hotel communications agent Harun Rahamad, 29, from signing up for his fifth Spartan Singapore race.

He says: "I want to prove to myself that I am not limited by my condition. I am always trying to see how far my body can go."

The Singaporean, who was born with cerebral palsy, experiences muscle stiffness in his left leg and loses his balance.

One obstacle which he found particularly difficult was the Atlas Carry, where participants must pick up a stone and carry it across some distance.

Mr Harun says: "Initially, my left leg felt too weak to walk while I was carrying the stone."

So in recent years, he started training more intensively to develop stronger leg muscles - running about 6km a week, sometimes wearing a vest with weights attached to it, as well as doing half-squats and various weight exercises.

This has paid off as he can now walk a longer distance while carrying a stone.

However, there are challenges such as traversing a vertical wall - which he simply cannot finish due to his disability.

"When this happens, I do the failure penalty of 30 burpees. It is also part of my regular training."

He trains regularly with Lion City Spartans, a group of fitness enthusiasts, where he is the only member with a disability.

The group's founder, Mr Muhammad Ismail Mahmood, 35, says: "Harun is definitely one of the biggest inspirations to the team. He has never seen his disability as a hindrance to achieving his goals. To be honest, I often forget about his disability because of his never-quit attitude."

Another disabled Singaporean, Mr Shariff Abdullah, 49, is a regular at physically demanding events.

The motivational speaker and para-athlete, who was born without a left foot and had his stump amputated after a skin infection in 2008, is known as Singapore's Blade Runner because of his carbon fibre blade-like prosthetic leg.

He has completed more than 25 marathons and countless other sporting events, such as Spartan Singapore races and Men's Health Urbanathlon.

In April, he will take part in the FWD North Pole Marathon in Norway. Billed as the world's "coolest marathon", the event involves running 42.2km on frozen ice floes, in temperatures as low as minus 30 deg C.

He says: "I see taking part in sporting events as a way of improving myself and inspiring others.

"In such events, just like in life, there are many obstacles. But as long as you have a never-say-die attitude, there is always a way to overcome these challenges."