What are they?
Health Balls, also called Worry Balls, Stress Balls, Melody Balls, Therapy Balls, Exercise Balls, Baoding Balls etc., were made roughly 2000 years ago in Baoding, China. They were used for martial arts training. Later, it was solely used by the Imperial family. Today, health balls are a treasured necessity for the Chinese as it helps to build up strength and promote health.
What do Health Balls look like?

Of a pair of balls, one sounds high and one low. They are usually gorgeously decorated with exotic designs and are often deemed as delightful little pieces of art. They are wear resistant, and are not easily breakable. The balls are generally heavy and within each is bell mechanism that produces a lovely and therapeutic sound while exercising. They come in different sizes to match the size of one's hand - usually the size of a golf ball.

What are the benefits?
According to the Chinese traditional medical theory of "Jingluo" (jingluo refers to the main and collateral channels, regarded as a network of passages through which vital energy circulates and along which the acupuncture points are distributed), the ten fingers are connected with the cranial nerve and vital organs of the human body, including heart, liver, spleen, lungs, kidneys, gallbladder, stomach, and intestine, etc. On plucking the iron balls with the fingers, the balls can stimulate the various acupuncture points on the hand, resulting in the unhindered circulation of vital energy and blood in the body. It can cause the jingluo (channels) unblocked and thorough, the vital energy and blood to function in harmony, thus prevent and cure insomnia & hypertension, relieve your fatigue, drown your worries, and, make the muscles nimble, the bones strong, the mind sober.
Exercise regularly with health balls can cure or prevent:
Arthritis
Arthritis usually affects many joints, most commonly the small joints of the hands. The affected joints become inflamed, painful, and swollen, and later deformed. In addition, there may be general symptoms such as weakness, fatigue and loss of appetite. Emotional stress appears to play a role. While stress is not a direct cause of rheumatoid arthritis, it can hasten progression of the disease.
Although it is not possible today to cure rheumatoid arthritis, it is possible for patients to cope successfully with their affliction using health balls. The prime objective of treatment is prevention of joint destruction.

Tendinitis
Injury or overuse of your tendons may cause pain, tenderness, and inflammation in the tendons or the tissues surrounding them, a condition known as tendinitis. Tendinitis can be related to job, sports, or household activities that require repeated twisting or rapid joint movements.
For prevention, have regular warm-ups with your miracle balls before doing activities that involve your hands.

Carpal Tunnel Syndrome
Carpal tunnel syndrome can be a very annoying condition and is often seen in the working population, especially in people using computers or keyboards. That includes you on the internet right now too!
The problem is when the canal in the wrist that houses several tendons and the nerve going to your fingers is too tight.
Classic carpal tunnel syndrome patients complain of numbness and weakness in their hand(s) with night pain; others present with a myriad of complaints, such as forearm discomfort or shooting pains up the arm, swelling, peculiar hand symptoms, temperature sensitivities and finger soreness.
Health Balls are perfect for treatment or prevention of this condition.

Memory Loss
If you find yourself having memory lapses at times Health Balls can help.
Rotating these balls within your hands help circulate internal energy throughout your body (qi or chi) that can help you decrease memory lapses.
Alzheimer's likelihood is also reduced as one becomes more alert.

Stress
Stress is a condition suffered by everyone in the 21st century! Health Balls are a great way to subdue your stress. Inside the health balls are small chimes, which create relaxing melodies when you rotate the Health Balls.
Balls that do not have chimes inside of them also carry stress relieving qualities during exercises. Whenever you become tired of work, walk around and play the health balls. In this way, your body will soon return to a relaxed and supple condition.

How to use?
To play with health balls, hold two balls of equal size and weight in one hand and, using the fingers, rotate them constantly. First practice rotating in the direction that is natural to you, and later practice rotating in the opposite direction only after you have become familiar with the natural rotation of balls. Beginners should practice with only one hand at a time, and alternately practice with either hands. Eventually, it is better to practice rotating the balls both clockwise and anti-clockwise alternately because they are complementary exercises, and in this way the full potential of the usage of hands will be realized.

Conclusion
Playing health balls would be an ideal exercise for people of all ages, especially the aged, because it is gentle. Practicing health balls open up a new horizon for one's dexterity and improve circulation of blood and inner air (Qi). One can combine this exercise with activities such as Tai Chi, walking on pebble paths or dances, etc. Why not get a pair of health balls and have fun while you enjoy the health benefits? Health balls are widely available over the net. If you can't get the proper ones, try rotating with large marbles.