Full study:
      Pubmed abstract, try to download from the options in the Research 101 section or email [email protected]

Background and objective:
      The current study was published in the peer-reviewed journal Research Quarterly for Exercise and Sport in September 2009.
     The purpose was to assess changes in body composition, flexibility and muscular endurance following 8 weeks of traditional mat Pilates training in a group of healthy recreationally active adults. Research documenting physiological changes following a Pilates protocol was (and still is) limited.

Methods (how was this research conducted):
      22 physically active participants completed the full study: 9 adults, who were new to Pilates, were assigned to a Pilates mat program. 13 adults served as control group doing a self-prescribed, unsupervised cardio-vascular and strength protocol with the same frequency.
 
Measurements:

• Weight, body fat percentage (skin fold measurements), 5 site circumference measures (waist, hip, chest, thigh and arm).
• Lower back and hamstring flexibility (sit-and-reach test).
• Upper body flexibility (shoulder reach test).
• Abdominal muscle endurance (Canadian curl-up test).
• Low back muscle endurance (45° incline back extension machine).

 
Intervention:

• Classical beginner and intermediate Pilates mat exercises (see table below).
• Frequency: 3x/week for 60 minutes.
• Length: 8 weeks.

 
Results:
      The control group demonstrated significantly greater abdominal and low back muscle endurance before the intervention.
      All measures except for weight, hip and thigh circumference improved significantly for the Pilates group, but not the control group, after the intervention.
 
Limitations (things to keep in mind):
      The strengths of the current study are found in its program frequency and length, as well as its statistical calculations.
​       It has, however, several limitations often encountered in exercise science research, which decrease internal and external validity. This doesn't mean that the results or conclusions are wrong, they can just be taken less seriously than the results of a study with greater validity: The number of participants was very small and mostly female, the participants had a relatively young average age due to the university setting, the groups weren't randomly assigned, the measurements weren't conducted blinded, and the control group’s exercise program was self-prescribed and unsupervised..

Implications (what this means for Pilates teachers):
      In spite of its limitations, this study is a great demonstration of the positive effects of a classical Pilates Mat program for clients.
      Its real importance however, lies in the fact that it is, to the author’s knowledge, the only study in MEDLINE that utilizes a classical Pilates protocol. This is indicated by the exercise selection and names, as well as the instructor’s background. She was certified at The Pilates Studio NY and trained with Elder Romana Kryzanowska.

Objective
      This first review does not introduce one, but several articles on low back pain, revealing limitations often encountered in Pilates research. 
​The goal of this article is to assess the effectiveness of the Pilates method in the treatment of chronic low back pain by reviewing scientific studies in which the Pilates Method was used as treatment. A critical look will be taken at the studies’ limitations and the types of exercises used.
The studies were required to meet scholarly standards, be peer reviewed and are randomized and controlled trials. 

Study inclusion criteria
      A Boolean search for randomized controlled and clinical trials using (Pilates) AND "low back pain" on PubMed (including MEDLINE) returned 24 results.

• 1 study was excluded because it was not available as full text.
• 1 study was only the protocol of a randomized control without results.
• 11 studies were excluded because they were reviews or not randomized controlled or clinical trials or because they showed up in the results without actually incorporating both keywords.
• 11 studies were selected.

The effectiveness of Pilates in the treatment of low back pain
      ​Regardless of the limitations of the selected studies described below, the success of Pilates-based exercise in the rehabilitation of low back pain is undeniable:

      ​Due to the different measurements and intervention ranges, there is no statistical data analysis possible. Following a comparative result list:

• 10 studies demonstrate greater beneficial effects compared to other exercise therapies or the control group.
• 1 study demonstrates similar beneficial effects compared to other exercise therapies or the control group.
• All 10 studies measure pain intensity (among other measures), which decreases post Pilates intervention in all studies.

General limitations in Pilates research
      Pilates exercises are being used by physical therapists to support the rehabilitation programs for various musculoskeletal conditions, sports injuries, and neurological disorders, focusing especially on the spine and its stabilization. The increased use of Pilates-based exercises makes it imperative to understand, among other characteristics, its applications, its contraindications, and how to use it appropriately.
As numerous studies about Pilates and low back pain have been authored, the following limitations were observed:

• Scholarly standards: Some studies don’t meet scholarly standards; the studies are not randomized controlled trials or clinical trials or are not peer reviewed.
• Measurements: Some studies use only subjective data analysis tools (scales and questionnaires) that evaluate parameters such as pain intensity and disability; others also use functional tests, such as balance and flexibility.
• Study methods: While subject numbers are generally >20, which is satisfactory, the most significant factors observed are the differences in intervention length and frequency, with 4 weeks being the shortest intervention time.

      Following are inconsistencies related to movement standards that influence scientific evaluation and are further detailed in subsequent pages:

• Pilates equipment: Most studies use only mat exercises, but some studies also use the original Pilates equipment, which is a different biomechanical approach. A few studies use equipment that is often associated with Pilates, but has its origin in fitness or rehabilitation, such as balls, therabands, and foam rollers.
• Type of Pilates exercises: Even though all studies claim they utilize the Pilates method or Pilates-based exercise, applications vary widely. Most studies use contemporary Pilates, none use the original, classical Pilates. The type of Pilates also determines another important factor, which is the amount of exercises given.
• Addition of non-Pilates-exercises: Some studies incorporate other types of exercises, such as movement protocols from physical therapy or yoga.

Classical Pilates, contemporary Pilates and therapeutic exercise
​(contributor: Heather King Smith)
      Following similarities and differences of classical Pilates, contemporary Pilates and therapeutic exercise protocols:

• Classical Pilates uses Pilates exercise names and adheres to a particular sequence of exercises on the two main pieces of equipment, the mat and the reformer. It uses equipment specifically designed for Pilates by the creator, Joseph Pilates.
• Contemporary Pilates uses Pilates exercise names, but there is no particular set sequence. Contemporary Pilates uses Pilates equipment as well as other equipment from the fitness and rehabilitation fields.
• In therapeutic exercise there are no Pilates names and there is no set sequence.

Additional differences are:

• Repetitions: <10x for classical Pilates, >10x for therapeutic exercise. Contemporary Pilates uses both approaches.
• Focus area: Classical Pilates is whole-body exercise, regardless of injury. In contemporary Pilates, additional exercises from the fitness and rehabilitation fields may be incorporated into a session to enhance optimal muscle recruitment and address weaknesses or injuries. Therapeutic exercise movements are mostly spot-specific and selected to strengthen the area of injury or weakness. The client is often asked to recruit certain muscles groups.
• Flow: In classical Pilates the client moves through the exercise sequence with a maximum of 10 repetitions per exercise. In therapeutic exercise, exercises are repeated until the desired muscle recruitment is achieved and the muscle is fatigued. Contemporary Pilates may combine both approaches.

Limitations: Exercise protocol definition and challenges
      Most of the exercises taught to physical therapists in the United States for  low back pain patients fall into general categories of spinal range of motion and strengthening exercises that may be described as core stability, dynamic stabilization, lumbo-pelvic and spinal stabilization, co-contraction type mat or ball exercises, progressive resistive exercises with weights or elastic bands, and functional activities.
      ​Where is the boundary between such therapeutic exercise protocols and Pilates? A comparison of the 11 selected studies shows that the Pilates protocol used is not always clearly defined and may not even be Pilates. 

      Surprisingly, 2 studies do not provide any information about the exercises used (Cruz-Díaz et al., 2015 & da Fonseca et al., 2009). Da Fonseca et al. only provide brief information about muscle recruitment concepts, which indicate that the protocol is more closely related to therapeutic exercise than to Pilates.
      Rydeard et al. (2006) provide a more detailed description about the exercises used, but the protocol is also about muscle recruitment strategies and doesn’t mention any Pilates exercises, in spite of the title of the study: “Pilates-based therapeutic exercise: effect on subjects with nonspecific chronic low back pain and functional disability”.
      Wajswelner et al. (2012) promise “clinical Pilates” in the study title, but they use therapeutic exercises which are performed on the Pilates equipment. It is questionable if the use of equipment makes the exercises Pilates exercises.
      Lastly, about a third of the mat exercises that Lee at al. (2014) use are yoga based, such as “seated hip stretch” and “knee over knee twist stretch”, not Pilates.

Conclusion
      There is evidence that Pilates-based exercise in the rehabilitation of low back pain is effective. Additional peer-reviewed and randomized, controlled research is needed to produce scientifically reliable meta analyses, preferably utilizing similar measurements, intervention durations, frequencies and equipment.
      ​For further scientific evaluation and in order to achieve reproducible exercise protocols and results, a standardization of contemporary Pilates exercises would be desirable. Classical Pilates has not been scientifically analyzed.