Every day in summertime, hundreds of people flock to an outdoor gym on an island in the Dnieper river in the Ukrainian capital, Kiev.

This unique gym dates back to the late 1960s when a subway line was built to link Kiev's historic right bank and the left bank, which became home to sprawling Soviet-era housing developments. One station, Hydropark, was built on the island, giving residents easy access to the park, and they immediately adopted it for jogging and picnics.

Yuri Kuk, the 70-year old bespectacled co-founder of the gym, said it all began with a simple horizontal bar to do chin-ups. Kuk, a mathematician who worked in a cybernetics research center, says it was easy to obtain materials and factory hands willing to shape the equipment in the 1970s, when Soviet heavy industry was still flourishing.

"There was a lot of scrap metal around, just lying about," he said. "We wanted people to have an active leisure time, not just play cards on the beach."

Nearly 50 years on, the gym boasts about 200 hand-made machines, from leg and arm trainers to more sophisticated contraptions.

The Hydropark gym is free of charge, but after Ukrainian authorities hiked electricity prices Kuk began to collect donations to keep the lights on at the gym when it's dark.

The gym is open all year round in the city where it's not unusual for temperatures to drop to minus 15 Celsius (5 Fahrenheit). A few dozen of die-hard gym fans visit and work out in wintertime when the island is covered in snow and the river freezes over.

Lush Kiev summertime is the best, Kuk says.

"It's nice that the Dnieper is nearby: you can take a dip after the workout," he said. "It's stuffy inside gyms in summertime. Here there is fresh air all year around."