The BASI Block System®

“Make a close study of each exercise and do not attempt any other exercise until you first have mastered the current one and know its routine down to the last detail without any reference to the text.”
—Joseph H. Pilates, Return to Life

Devised by BASI Pilates founder Rael Isacowitz, the Block System is a unique and specialized ‘filing’ system for the hundreds of exercises in the Pilates repertoire. It categorizes them in a logical sequence and ensures the progressive structuring of classes within a flexible framework. This system is the foundation of the BASI methodology.

The singular value of the Block System for a Pilates teacher is well described by BASI senior faculty member Theo van der Riet: “When I started out teaching Pilates (not BASI Pilates at that time) I taught exercises randomly. It was like grabbing exercises from the air as they floated around without purpose. My appreciation for the Block System began when I understood that, in a class of 12 clients, say, I could tailor the routine to the needs of each individual without teaching the same exercises to 12 people—while challenging all of them within their range of movement and ability.”

The Block System encourages progressive thinking within a structure, a plan, a map. It enables the instructor to construct a class that is balanced, well-rounded and addresses all planes of movement and multiple muscle groups. In short, the Block System is a methodology for categorizing exercises and using them to structure routines.

As is clear from the name, the Block System categorizes each exercise in the Pilates repertoire into one or more of 12 Blocks:

  • Warm Up
  • Foot Work
  • Abdominal Work
  • Hip Work
  • Spinal Articulation
  • Stretches
  • Arm Work
  • Leg Work
  • Full Body Integration
  • Lateral Flexion
  • Lateral Rotation
  • Back Extension


There are multiple exercises to choose from in each Block. The challenge for the instructor is often in deciding which exercise or exercises to choose. It takes years of experience and a very skilled instructor to fully understand and comprehend the many complexities and intricacies of the Block System.

The criteria which come into play when choosing an exercise include:

  • Experience of the client, e.g. 6 months, 2 years
  • Level of the client, e.g. beginner, intermediate
  • Goals of the client, e.g. posture, weight loss
  • Restrictions, e.g. injuries
  • Specific population, e.g. athlete, dancer, mature client, pregnant client
  • Time available, e.g. 30 min to 60 min
  • Progressive class structuring, e.g. from session 1 to 20
  • Maintaining flow throughout the session


The beauty of the system is that the instructor can construct a class that suits the ability of each individual client, without compromising on their specific needs or restrictions.

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