This "squishiness," George Clarifies, "enables the user to wedge it driving their back for Main do the job or squeeze at the rear of their knee for glute exercises. When the ball is too stiff, it might be tricky to hold on to or put the human body in uncomfortable https://advertisesmart.com/view/post/The-Benefits-of-Isometric-Exercises-and-How-to-Do-Them-Correctly/60