Exercise balls are made from inflatable plastic that’s hard to puncture and, generally range in diameter from 35 and 85 cm.

Exercise balls were popularly used for physical conditioning in Switzerland, which is why they’re sometimes called Swiss balls. 

People choose exercise balls for workouts because they’re a great means of toning and sculpting muscles, attaining core strength and improving posture.

Your body has to balance and react to the instability of the ball, with the result that your chest, abdominal, back and hip muscles are actively engaged. When core muscles strengthen, your balance and coordination will improve and so will your lumbar, or lower back, mobility. The activity also increases blood flow to your back and joints.

Exercise balls are also helpful for doing movements where you need flexible support such as post-injury rehabilitation. You can target muscles that regular sit-ups don’t effectively impact, which is why these unfussy spheres have also become popular with elite athletes.

For your own safety and for the efficacy of the workout, the most important thing to consider when choosing an exercise ball size is your height.

When you stand next to the ball, it should reach your knees or slightly above. You want your bent legs to easily form a right angle when sitting so that your thighs are parallel to the floor.

• If you’re shorter than 5 feet, go with an 18 inch (45 cm) diameter
• If you’re between 5 feet and 5 ft 7, you're going to want a ball that is 22 inches (55 cm) in diameter
• Between 5-foot-8 and 6-foot-1, we’re talking a 65 cm diameter
• For the really tall folks, a 75 cm ball should do the trick

PROS

• Exercise balls flatten out with your weight making them surprisingly more stable than expected.
• You need to find your center of gravity, a neutral positioning of the spine where your upper body is balanced on a stable pelvic base. That helps relieve pressure on the spine, reducing and relieving back pain.
• Short periods of ball sitting will help strengthen your core and balance.

CONS

• Long periods of ball sitting will not be comfortable for those without the core strength to sustain correct posture for extended periods.
• Upper body strain because balls have no armrests.
• There’s a lack of supporting scientific evidence to show that choosing an exercise ball to sit on instead of a chair has any significant benefits.

 Bouncing on an exercise ball engages your core because you need to stay upright and balanced. Bouncing is one way to do pelvic rotations which promote better circulation in your spine.

 To bounce correctly, you need to plant your feet on the ground hip distance apart, sit up nice and tall, and pull your belly button in. Let your feet lift off the floor when you’re bouncing up, and switch up your arm movements because bouncing alone won’t give you a well-rounded workout. 

 Fun fact - pregnant women often choose exercise balls to support their extra weight during prenatal workouts. And their use doesn’t end there – they can also be used as a birthing aid to help with contractions during delivery.