Although it is allowed under racing rules, as long as the stipendiary stewards have ascertained the required level of riding ability, trainers can ride in the trials.
But it is a rare sight, even when the trainers are former jockeys with years of riding experience.
So, when Singaporean trainer Kuah Cheng Tee's name was announced in the trial sheets at Kranji on Thursday morning, it took many by surprise.
The former jockey rode his one-time winner Winning Hobby in the fifth of six trials and followed up on Household Dynasty in the final trial.
He led but finished last of seven runners on Winning Hobby and was second-last, also in a seven-horse field, on Household Dynasty.
Like champion jockey-turned trainer Saimee Jumaat, Kuah rides trackwork on his horses in the mornings.
But, on Thursday morning, he came full circle, riding in race-like conditions, instead of galloping a horse alone or in the company of a stablemate or two.
Kuah said the last time he was engaged in the trials was about 10 years ago, when he was assistant trainer to Mok Zhan Lun.
He also trialled horses when he worked for Kranji-based Japanese trainer Hideyuki Takaoka.
There was no manpower crisis in his stable, but the consummate horseman just felt it was time to get back into that 1,000m hit-out mode.
"I used to ride in trials when I was still with Takaoka. I also had a few runs as B-trainer with Mok," said Kuah, who rode 38 winners as a jockey from the late 1990s to 2003.
"Somehow, I stopped riding in trials when I got my trainer's licence (in 2016), but I've always wanted to do it again one day.
"It gives me a better feel of the horses, especially in terms of their fitness level.
"I rode Winning Hobby and Household Dynasty, and I can tell you Winning Hobby is still not fit.
"He had a left knee spur surgery and he is still some way from a racing comeback. He led but he could not keep up and finished a long last in the end.
"Household Dynasty has run only four times and ran second at his last start. I hope he can improve this year."
Clad in his own purple heart on silver silks, Kuah was seen puffing a little after he jumped off Household Dynasty.
He copped a fair bit of ribbing about his fitness, but the 44-year-old trainer jovially brushed it off.
"I was fitter than Winning Hobby, I could have ridden another three trials," he quipped.
Saimee, 48, said he did not see the need to ride in the trials at the moment but he would when needed.
"Never say never, right?" he said, with a laugh. "I always enjoy riding, so when needed, I'll ride one day.
"Sometimes I feel like riding again in the races."