A free self-defence course devised for women after a high profile assault in Vancouver in 2015 is seeing increased numbers after a alarming attack on Thursday in Burnaby.

RCMP continue to investigate and have released a sketch of the man they believe is responsible for an attack on a woman on a small path off the Urban trail, south of Lougheed Highway.

Officers have also cautioned people from walking alone in the area.

"When I think about the situation, my heart is going," said Angela Kromidas. "So it's quite alarming. You could be out in the middle of the day."

Ryan Diaz created the free self-defence course last year after another violent sexual assault happened in Vancouver's Strathcona neighbourhood.

Ryan Diaz DCS Fitness

Ryan Diaz of DCS Fitness created a free self-defence course for women after a violent sexual assault in Strathchona in 2015. (CBC)

"There's a lot of sickos out there that do stuff like this, we need to arm women with the power to defend themselves," said Diaz who is the owner of DCS Fitness.

"You have to teach men that it's not right [to assault women]," said Doreen Ram who was at Saturday's course, which some women signed up for at the last minute. "And as women, we do have to defend ourselves, which is the sad part about it."

"I don't feel as vulnerable knowing ... what might be going through their mind and calming myself down and knowing the situation," said Ruby Dhaliwal.

Diaz has offered five one-day classes since April 2015.