With better air quality over the past week, exercise groups are resuming outdoor activities that were put on hold or disrupted during the prolonged haze in the last two months.

Training is back on track for local running group Team FatBird, for instance. Attendance at its training and weekday group runs is now back to pre-haze levels.

The group had to cancel almost three-quarters of its weekend marathon training sessions and weekday group runs owing to the unhealthy haze conditions in September.

It also had to cancel training sessions for next month's Standard Chartered Marathon.

"It did disrupt a number of our runners' preparations as some were training for overseas marathons," said the group's chief running officer Anthony Sum.

"Those who were training for competitions made do with indoor training and also sought out odd windows of opportunity when the haze levels were lower, to get their long (outdoor) runs in."

The haze also affected cyclists from LoveCyclingSg. But with the weather clearing up, they are once again hitting the road.

"All rides are 'go'," said the group's co-founder, Mr Woon Taiwoon, 40, referencing a line from Thunderbirds, a 1960s British science-fiction TV series.

During the haze period, organised rides were cancelled when the three-hour Pollutant Standards Index hit 150 and above.

"Folks were a bit unhappy about the ride cancellations but they understood why," said Mr Woon.

Being forced to train indoors was "frustrating and worrying" for user experience designer Darren Siow, 44, who felt that the haze had compromised his and his wife's preparations for their first Ironman triathlon in Australia next month.

"It was mainly the swim training that was most affected, since Singapore doesn't have many indoor pools," said Mr Siow.

"We were forced to do cycling and running in the gym, which is not so bad but there's a big difference with running or cycling outside."

Several members of Singapore Adventurous Nature-Lovers, an outdoor nature and trekking group, have also resumed their vertical training climbs at stairwells.

Hazy conditions in the last two months led them to reduce the frequency of the climbs, which help them gear up for overseas hikes and mountain expeditions.

"We do stair-climbing, but it's hard to find a building with enclosed stairs that's tall enough," said founder Chua Tien Seng, 48. HDB blocks are sufficiently tall but the stairs are not enclosed and are exposed to the haze, he added.

Organisations that had to cancel or postpone outdoor events and programmes in the past two months have also resumed most of these activities.

Outward Bound Singapore (OBS) said several schools and groups cancelled their OBS programmes to safeguard the health of participants when the haze was at unhealthy levels.

"With the improved haze conditions, most of our programmes have resumed," said an OBS spokesman.