Hiromi Soga scanned the fabricated stones jutting out from a 4m-high climbing wall at an indoor gym in Kawaguchi, Saitama Prefecture, one day recently, carefully determining the best way to approach her ascent.

As she slowly began scaling the wall, her climbing buddies started offering her encouragement.

"Pick that holder by your right foot. You can make it!" Kazumi Korenaga shouted.

" You need to extend your left arm a little bit. That's it!" Wakana Koyama urged.

It took about five minutes for Soga, 37, to grab the holder on the top of the wall with both hands. "There's nothing to match the sense of achievement you get when reaching the top of the wall," Soga said, wiping perspiration from her brow.

Bouldering is a kind of rock climbing usually done without a rope and other protective gear.

In indoor bouldering gyms, people practice their skills using artificial walls with plastic climbing holds of various shapes and sizes that resemble natural rock faces.

In recent years, bouldering has been enjoying increasing popularity in Japan, especially among homemakers, with more and more specialist facilities sprouting up.

Soga took up the sport in May. Initially, she had merely been accompanying her 8-year-old daughter, who began visiting the Pump 1 gym two years ago.

However, as she watched her daughter climbing the wall, Soga became frustrated at the lack of advice she was able to offer her.

"I thought I'd be able to offer her advice if I could experience bouldering for myself," Soga said.

Once she started climbing, Soga quickly fell under the sport's spell.

She now visits the gym once a week with Korenaga, 38, and Koyama, 36. "We call our activities the 'bouldering club'," Soga said.

On bouldering days, Soga first visits the gym without her daughter shortly after noon. After grappling with the wall for about two hours, she returns home to prepare lunch.

Then, Soga and her daughter head for the gym where they enjoy the sport until dinner time.

Soga wakes at 6am each morning. Her day begins by preparing breakfast for her daughter and husband, who is a company employee. She then takes care of such everyday tasks as laundering, cleaning, shopping for food.

She also has to take her daughter to and from cram schools. Soga explained that this schedule leaves her feeling exhausted and bouldering helps her feel refreshed.

Tosho Associate Corp, a company that designs and constructs bouldering walls, will launch and manage a large bouldering gym in Edogawa Ward, Tokyo, this month. The company is hopeful that many homemakers in the area will use the gym.

Though homemakers can plump for many other sports such as volleyball, tennis and aerobics, Tokyo Kasei-Gakuin University Prof.

Kazumasa Kaneko, a specialist in outdoor education, said: "Surprisingly, there aren't that many sports that meet the conditions required by most homemakers, such as playing the sport at their own pace. Producing tangible accomplishments as result of their efforts (is another important factor)."

Makiko Nakada, a 39-year-old homemaker of Funabashi, Chiba Prefecture, visits a bouldering gym in the city twice a week. "My daily life is taken up with child-rearing. Bouldering is the only time I have for myself," Nakada said.

Nakada said her muscles have developed significantly since she started bouldering, especially the muscles around her shoulders. Recently, she has been unable to wear her wedding ring.

However, her husband, Takanari, 40 seems to be happy. "Her body has firmed up - she's growing younger every day!" he said with a smile.