Mobility exercises with fitness equipment can provide more leverage to take a limb through a greater ROM while also increasing muscle fiber activation to help improve muscle contraction patterns. The stability ball creates two unique challenges for the body: 1) The unstable nature of the ball can cause muscle contraction, which is an important part of mobility training. As one set of muscles contract to maintain stability, the muscles on the other side of the joint will have to lengthen to allow the muscles to contract. 2) The shape of the ball creates a unique lever that can help move the body into positions that lengthen muscle and connective tissue while enhancing joint motion. For best results, use a fully inflated stability ball, as this will create the instability for enhanced muscle activation while providing a stiff surface to optimize leverage into a joint position. Once you reach 20 reps per each side, work up to doing 4 sets of each exercise; for the stretches, keep the length of time the same, but feel free to add additional sets.
When selecting a stability ball, use a 55-centimeter ball if you're 5' 7" or shorter.
Select a 65-centimeter ball if you're between 5' 7" and 6' 4". Select a 75-centimeter ball if you're taller than 6' 4". The ball should be inflated until it's firm and you can sit on it so your knees and hips can comfortably hold a 90-degree bend.