[Pilates balls to train the core and balance] With a diameter of 65 cm, the TRNR Stability Ball is an indispensable instrument for strengthening core strength, balance, coordination, flexibility, joint stability, and posture. The instability that this ball brings causes the core to work harder, including the deep abdominal, back, and pelvic floor muscles, which helps strengthen these important but often overlooked muscles. This helps prevent muscle imbalances, back pain, and injuries. While it's particularly effective for core training, the Stability Ball is versatile enough for a variety of workouts targeting the arms, hips, buttocks, and legs. It comes with a manual pump and a TRNR tool for inflating exactly to the recommended size (aligning the two holes with the marks on the ball) and the fork-like end makes it easy to remove the plug.