To mark this year's Olympics, hot tub/swim spa manufacturer Master Spas hosted a challenge in one of the swim spas from its Michael Phelps collection.

The event took place during the U.S. Olympic Swim Trials from June 26 to July 3 at the USA Swimming Aqua Zone, a 100,000-square-foot fan experience area outside CenturyLink Center in Omaha, Neb. A model from the Fort Wayne, Ind.-based manufacturer's MP Signature line was used.

Swimmers of all ages lined up to compete for bragging rights and a free t-shirt. Participants were given a short warm-up period upon entering the swim spa, then the propulsion system was increased to Michael Phelps’ current training pace – 92 out of 100 on the spa’s Wave XP Pro Propulsion System. Challengers tried to last three minutes at his pace.

"During the challenge, the current is set at the pace Michael Phelps uses for training, which is pretty fast, even for experienced swimmers," said Kevin Richards, Master Spas vice president of sales and marketing. "And he swims for 12 minutes at that pace."

The top ten winners, grouped by age (8-12, 12-17, and 18+), were displayed on a leaderboard. Some swimmers returned more than once to improve their times.

Most participants were on their own swim teams, according to Susan Rekeweg, marketing coordinator for Master Spas. However, to ensure safety, Rekeweg said three to four people were positioned around the spa and children were required to have parental permission.

Swimmers who wanted additional coaching and practice could head over to the swim clinic, also hosted on location by Master Spas, to receive individualized instruction from coaches who specialize in Michael Phelps Swimming, a swim instruction methodology developed by the Michael Phelps Swim School.