The instructors at Pendleton Pilates’ four locations teach 125 classes each week, showing students how to elongate and strengthen their muscles on mats and the studio’s reformer machines. During each group or private session, instructors customize workouts that use a rotating selection of 500 core-focused movements developed by Joseph Pilates in 1945. Additional classes include sessions in which students use parallel ballet barres while performing Pilates exercises, as well as spinning classes at the Westchester location.