Pilates “knee-stretch” exercises done from a quadruped position can effectively condition muscles that stabilize the lumbar spine, according to a study published in Archives of Physical Medicine and Rehabilitation (2010; 91 [1], 86–92). Researchers from the department of physical therapy, speech and occupational therapy, University of São Paulo, Brazil, conducted a small study with 19 healthy male and female subjects who were either Pilates instructors or ballet dancers with a minimum of 6 months of Pilates training.

The study’s purpose was to evaluate and compare activation of trunk flexors and extensors and hip muscles in four variations of the Pilates knee-stretch exercise done on the reformer. Investigators attached EMG (electromyography) sensors to subjects to collect data on muscle activation during performance of these exercises. Data analysis showed that greatest activation of the multifidus muscle, key to lumbar stabilization, occurred in exercises that involved the following: (1) changes in pelvic position from a posterior tilt and flexed trunk to neutral pelvis with trunk inclined relative to the ground; and (2) changes from a neutral pelvis to a forward tilt with trunk extended.

Study authors suggested that knee-stretch exercises with a neutral pelvis could be used as a stabilization exercise in early stages of rehabilitation to help with motor control, maintenance of pelvic position, and dissociation between pelvic position and hip movement. To challenge the multifidus and internal obliques, as well as to improve dissociation between pelvic position and hip movement, knee-stretch exercises with a forward pelvic tilt and an extended trunk could also be done.