Fitter and faster players will form a key part of the Football Association of Singapore (FAS)'s revamp for future editions of the S-League.
The governing body will introduce the Yo-Yo Test next season as a replacement of the 2.4km test, which served as the mandatory fitness examination for all professional footballers here.
While the passing mark is yet to be confirmed, the FAS told The Straits Times assessments will be conducted twice or thrice throughout the new term, set to run from March 31 to the end of October.
Previously, outfield players in the S-League had to clock below 9min 30sec in the 2.4km test - introduced in 2013 - just once at the start of the season. The Beep Test, which is a variation of the Yo-Yo Test, was used in the league for a decade before it was dropped.
Hougang United head of sports performance Dirk Schauenberg, who was German club Fortuna Dusseldorf's strength and conditioning coach from 2008 to 2013, said the switch made sense.
He added: "The 2.4km test is a one-tempo running test unrelated to football. Football is a stop-and-run sport which is more related to the intermittent shuttle run.
"Here, you run in different speeds and have short periods of rest. It is the closest to football's objectives, but not exactly as the sport is played with a ball and against another team, which requires a different type of fitness."
The Yo-Yo Test requires participants to run between two points that are 20m apart within set intervals as determined by a series of beeps. As the test progresses, the interval shortens, forcing the athletes to increase their speed over the course of the test to keep up with the pace.
While this must be done continuously in the Beep Test, there is a five-second recovery period between each stage in the Yo-Yo Test.
The Yo-Yo Test has been employed globally across different sports, including rugby sevens and netball.
In October, the Board of Control for Cricket in India (BCCI) made it compulsory for its national players. BCCI chief executive Rahul Johri told The Indian Express then that "the grade needed to be achieved is 16.1, which is the minimum standard set for an elite international sportsman" and added that the bar will be raised in due course.
Not everyone is convinced though. A former Singapore international, who declined to be named, said the Yo-Yo Test could rob the S-League of its stars.
He noted: "Players like Ahmad Latiff, Mirko Grabovac and Qiu Li struggled to pass the Beep Test but they could out-run opponents, score goals and excite fans.
"Some positions, like a centre-forward or a centre-back, don't have to run as much as a box-to-box midfielder or a wing-back, so it would be a shame if talented players are forced out just because they cannot pass the Yo-Yo Test."
But Koh Mui Tee, general manager of Albirex Niigata, the two-time S-League champions who are widely regarded as the fittest side in the league, feels a more stringent test was necessary to raise overall fitness levels.
He said: "The changes are made to improve the S-League, as well as the national team, to help local footballers meet demands of modern football.
"The Lions have conceded late goals in international matches recently against Bahrain and Turkmenistan. In the S-League, we scored the most (16) and conceded the least (four) in the last 15 minutes of a 24-game season."
National vice-captain Hariss Harun, 27, agreed and added: "In the long run, the aim should be for the S-League clubs to take control of this aspect.
"But as the league is going through changes now, this can be the way forward until things stabilise. We definitely need better fitness standards to better or at least match Asean and Asian teams."
There is no short cut to success, noted Schauenberg.
"It's the players' dream to be professionals, and if they have earned a contract, they have to stay at the highest level of fitness. They can't relax and be lazy."