Water exercise has long been known as a great way to achieve fast fitness, especially for those who find land workouts to be too painful on joints and muscles. Now researchers report that low-impact water routines not only strengthen muscles and aerobic fitness quickly, but may be the fastest way to alleviate the chronic pain and tenderness caused by the arthritis-related condition fibromyalgia.

In two studies, scientists in Brazil and Europe find women with this mysterious chronic condition achieved remarkable results after just a few months of water jogging and other pool-done aerobic and strengthening sessions. Fibromyalgia affects as many as 6 million Americans — nearly 80 percent of them women — causing intense and widespread pain in muscles, ligaments and joints; fatigue; and sleep problems.

Scientists in Finland and Spain find that women with fibromyalgia improved their thigh muscle strength by 20 percent after one-hour long exercise sessions in waist-deep warm water, done three times a week for three months. More importantly perhaps, their pain level decreased an average of 29 percent compared to pre-study levels, and they reported a 93 percent improvement in their ability to do day-to-day activities. But once they stopped the water workouts, their pain intensity returned to previous levels.

In the other study, Brazilian researchers say that 60 fibromyalgia patients who completed 15 weeks of deep water jogging enjoyed a similar level of aerobic and muscle strength improvement as another study group doing a similar workout on land — along with a substantial 36 percent reduction in pain intensity compared to their pre-workout levels.

Both studies were published in the medical journal Arthritis & Rheumatism: Arthritis Care & Research. Researchers believe the benefits result from the healing power of warm water, the low impact of water’s buoyancy or the increased resistance of water exercise — or some combination. More study is underway. A backyard above ground pool may be the solution.