We should not keep drawing-in the abdominal wall during the Pilates classes. Part I
1. Introduction
The Pilates method is characterized by a list of principles, two of which are Breathing and Centering. The Breathing principle pays a great deal of attention to the localization of the breathing movement and the organization of the inhalation and exhalation during the different phases of the exercise. The Centering principle arises as a development of the traditional principles, and it requires concentration on the “center,” a continuous band front and back, between the bottom of the ribcage, and the line across the hip bones (Latey, 2001). As a result of the combination of both principles, it has been suggested that during the Pilates Breathing pattern, a voluntary and conscious activation of the abdominal muscles, focused on drawing in the abdominal wall, and paying attention to the behavior of the abdominal region for the correct activation of the transversus abdominis muscle (Merrithew Corporation, 2001).
In the last few years, several studies have provided evidence that the “abdominal drawing-in”cue may not be that beneficial, and it may even impair stability and control of the lumbo-pelvic region within the healthy population (Aragon Salamanca, 2024).The goal of this article is to provide a new perspective a clear “Take-Pilates-Classes” Messageon whether or not this abdominal drawing-in maneuver should be a rule applied by Pilates practitioners. We strongly believe that it is very important to bring this topic to the attention of the Pilates community given the importance of the Pilates Method as a preeminent exercise.
We coulddescribe three main reasons or three main lines of thought that explain why the “abdominal drawing-in maneuver” (ADIM) also named “abdominal hollowing maneuver” (AHM) is used during Pilates practice:
a) Because we want to do a selective activation of the Transversus Abdominis.
b) Because we want to improve the lumbo-pelvic stability.
c) Because we want to keep the traditional way of the Pilates Method.
2. Results
We discuss each of the lines of thought in tun:
a) Because we want to do a selective activation of the Transversus Abdominis.
The Transversus Abdominis (TrA),a local muscle of the core region,has an important role in the prevention and rehabilitation of low back pain (Lynders, 2019).As a local muscle, the TrA has been characterized by its tonic activity, slow-twitch (type I) fibers with low threshold activation, and appear to be biased for low-load activities (Comerford and Mottram, 2001)(Caplan et al, 2014). Therefore, its retraining should be done in a specific andisolated way from the global core muscles to retrieve its low threshold tonic recruitment for low-load tasks (Richardson et al, 2007). The basic strategies for the isolated TrA muscle training are performed in static positions, with low load for a low threshold recruitment of the tonic fibers, plus an isometric contraction through an abdominal drawing-in action, and a neutral lumbo-pelvic alinement (Richardson et al, 1992) (Comerford, 2004) (Figure I-A).
Figure I-A: TrA muscle retraining in supine by means of a controlled drawing the abdominal wall while using a Stabilizer Pressure Biofeedback. B: A Stabilizer Pressure Biofeedback with an air pressure gauge to detect unwanted lumbo-pelvic motion. Taken from Aragon Salamanca, 2024 under CC BY-NC 4.0
According to Mottram and Comerford criteria,most of the Pilates Protocol Exercises are dynamic and high-load tasks with a more “stability and core strengthening”goal(Mottram and Comerford, 2008), rather than a specific training of the TrA. Examples of high-load tasks which require pelvic stability are represented in figure II. Therefore, most of the Pilates exercises do not meet the requirements for a controlled isolated activation of the TrA muscle; in fact, most Pilates exercises better match the concept of core strengthening. The “Take-Pilates-Classes” Message is that performing ADIM during the Pilates practice becomes not very effective for the purpose of TrA muscle isolation.
Figure II. Examples of high-load tasks (a, b) according to Mottram and Comerford criteria (2008), and examples of the Pilates version of these exercises (c, d). Taken from Aragon Salamanca, 2024 under CC BY-NC 4.0
The teaching process for the correct execution of the ADIM for an isolated activation of the TrA muscle seems to be very difficult and time demanding (Teyhen et al, 2005). In order to get a strictly controlled isolated contraction of the TrA it is very common to require the use of an ultra sound imaging or a stabilizer pressure biofeedback unit (Figure I-B) (Henry and Westervelt, 2005). The application of the ADIM with no feedback or without good control elicits the voluntaryactivation of global muscles of the core (Oshikawa et al, 2020), which would impair the selective retraining on the TrA(Richardson et al, 2007). It has been suggested that a not-well-tunedvoluntary activation of the global muscles, which may suppose an inappropriate spine stabilization, could confuse the nervous system stability perception and, consequently, the local muscle activation may not be started (Richardson et al, 2007). The voluntary contraction of the global muscles could prevent the anticipatory activation of the local muscles(Bergmark, 1989). The “Take-Pilates-Classes” Message is the application of the ADIM during most Pilates exercises compromises the implementation of an effective isolated activation of the TrA muscle, which could impair the optimal spine stabilization.
Another effect of the contraction of the TrA muscle is related to the Inter-Rectus Distance (IRD). It has been pointed out that the contraction of the TrA, the Pelvic Floor Muscles, or a combination of both contractions, increased the IRD in post-partum women with diastasis rectus abdominis (DRA) (Theodorsen et al, 2019) and the AHM may not be beneficial for subjects with severe abdominal DRA, hernia repair, or severe uncorrected abdominal hernia (Lynders, 2019). The activation of the TrA before a curl-up results in a relatively wider IRD than during an automatic curl-up (with no pre-activation of the TrA) in women with DRA (Lee and Hodges, 2016). The execution of a curl-up or abdominal-crunch without any conscious maneuver for the activation of the TrA muscle decreases the IRD in postpartum women (Pascoal et al, 2014). All these give us another important reason to raise the topic of avoiding the ADIM as a general application tool during the Pilates classes. The “Take-Pilates-Classes” Message is the ADIM can increase the IRD under DRA conditions.
The compressive forces of the lumbar spine are increased during the abdominal muscle contraction (Van Dieen et al, 2003). If we assume that during a regular core-exercise or a regular daily activity the abdominal muscle should be activated, as a natural effect of the task requirements, and if we impose an extra level of contraction through conscious activation of any specific core muscle, we might be putting an extra level of compression in the spine. According to Lederman, this continuous activation of the core muscles can potentially jeopardize the structures of the spine, and “Patients who have been trained to use complex abdominal hollowing and bracing maneuvers should be discouraged from using them” (Lederman, 2010). Already in 2010 Lederman was very clear about it. The “Take-Pilates-Classes” Messageis that the use of ADIM should be discouraged.
The foundation base of cueing a voluntary contraction of the abdominal wall for postural stability control seems to go against the fundamentals of Neuroanatomy. Neuroanatomy tells us that the neuromotor system has two descending pathways for the motor signals from the brain to the lower motor neurons (Lee and Muzio, 2022). Thesepathways are split in Pyramidal and Extrapyramidal tracts. The Pyramidal tracts give motor signals for the conscious control of the muscles of the body. The Extrapyramidal tracts carry motor signals for the unconscious, reflexive, or responsive control of the type I slow-twitch tonic motor fibers, muscle fibers with a dominant postural and control balance roles (Lee and Muzio, 2022) as the TrA fibers.Interference with this natural reaction in healthy people with a conscious activation of specific muscles may impairs the stability strategies of the nervous system.If we train these muscles with phasic conscious exercises could lead to a muscle tone dysfunction (Cabañas and Chapinal, 2014). Again, the “Take-Pilates-Classes” Message is ADIM may interfere with the postural control goals of the Pilates Method.
a) Because we want to improve the lumbo-pelvic stability (LPS).
As we have seen, the ADIM aim is to get a specific activation of the TrA muscle. TrA is considered a local muscle with an essential lumbar postural role through the Intra Abdominal Pressure control but with a limited capacity to control the orientation of the lumbar spine (Richardson et al, 2007) (Bergmark, 1989). Local muscles of the core are essential for the stability of the lumbo-pelvic region but not enough for its orientation control, while Rectus Abdominis (RA), as a muscle part of the global system, is critical for the direction control of the spine and transfer of loads from thorax to pelvis(Bergmark, 1989). The RA muscle has the capacity for pelvic orientation control when the thorax is a fixed point (Neuman, 2010) (Kendall et al, 2007). RA is the most important abdominal muscle in order to correct the lumbar lordosis through the control of the anterior pelvic tilt thanks to its large lever arm (Kapanji, 2017).
The Internal Oblique (IO) is considered another local muscle of the core area, and is associated with the TrA in the maneuver of drawing the abdominal wall in (O’Sullivan, 1998). During a high-load task like a “Plank” and a supine “Double Leg Raise”, the RA activation is higher than that of the IO (Park and Park, 2019). Furthermore, during an unstable “Plank” position, on a TRX, the RA activation (88,3 %MVC) was even higher than for the EO (Topcu et al, 2022), giving an idea of the important input of the RA global muscle during these high-load core stability exercises.The anatomy analysis of the horizontal orientation of the muscle fibers of the TrA and the vertical orientation of RA muscle fibers show a mostly perpendicular relationship between both muscles (Neuman, 2010) (Kapanji, 2017). This perpendicular relationship could put both muscles in a sort of competitive situation because when the TrA contracts, pullingfrom the connective tissues of the RA sheath, it stretches the RA fibers (Lee D and Hodges,2016), compromising its concentric contraction direction (Figure III).
Figure III. The concentric contraction of the TrA fibers pull from the RA, stretching its muscle fibers. TrA: Transversus Abdominis. RA: Rectus Abdominis. Taken from Aragon Salamanca, 2024 under CC BY-NC 4.0
Besides, the EMG analysis of the core muscles showed that ADIM decreases the RA activation and increases that of the TrA (Oshikawa et al, 2020) (Kim and Oh, 2015) (Vera-Garcia et al, 2007): when one decreases the other one increase, which may give us another indication of this competition.
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During low-load tasks local muscle input is greater than global muscle input (EMG data from Biscarini et al., 2018). During high-load tasks global muscle input is greater than local muscle input (EMG data from Park & Park, 2019). During a Leg Pull Front, a high-load Pilates exercise, the ADIM was less effective at controlling the pelvic rotation [Jung & Oh, 2022], perhaps because the drawing-in maneuver impaired global muscle input, the main source of stability (Figure V).Therefore, the “Take-Pilates-Classes” Message is that excessive activation of the TrA or the IO during the ADIM could compromise the RA input for pelvic anterior tilt control and hyper-lordosis control during high-load tasks such as some of the Pilates exercises.
Figure V. IO: Internal Oblique. RA: Rectus Abdominis. MVC: Maximal Voluntary Contraction. AHM: Abdominal Hollowing Maneuver = ADIM. Taken from Aragon Salamanca, 2024 under CC BY-NC 4.0
a) Because we want to keep the traditional way of the Pilates Method.
There are several people who argue that if you do not apply the Pilates method in the original way, you are not doing real Pilates. The Pilates Method was made known by several of his early assistants who opened their own studios and developed some new approaches to the original principles (Latey, 2001). Today, there are several Pilates franchises and “schools” who have developed their own list of Principles.
In our opinion, the Pilates Method has been evolving from the very beginning and it should integrate all relevant new knowledge and scientific evidence to remain one of the most important exercise techniques in the motor control and postural education field.
3. Conclusions
In order to provide a new perspective on whether the ADIM should be a rule applied by Pilates practitioners we have reviewed recent literature. Our main conclusions are:
Concerning the use of the ADIM to perform a selective activation of the TrA muscle, our opinion is that, although ADIM can increase TrA activation, Pilates exercises do not meet the requirements for isolated TrA-specific retraining. The application of ADIM during Pilates exercises, without quality control of the TrA activation, could impair spinal stabilization strategies. Enhanced activation of the TrA during ADIM increases the IRD under DRA conditions and is discouraged in patients with hernia repair or severe uncorrected abdominal hernia. The continuous conscious activation of the core muscles can potentially jeopardize the structures of the spine.Neuroanatomy concepts contradict the use of a conscious muscle activation technique, such as ADIM, to enhance the postural tonic role of the TrA muscle.
With regard to the use of the ADIM to improve LPS, we conclude that excessive activation of TrA during an ADIM, an essential but ineffective local muscle for pelvic orientation control, may interfere with RA input for pelvic directional control during high-load Pilates exercises. The AHM is less effective at controlling pelvic rotation during two typical Pilates scenarios, an “active supine straight leg raises” and a “front Plank.”
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Julio C. Aragón-Salamanca graduated in Physical Activity and Sport Sciences from the University of the Basque Country and holds a Master’s degree in Sport Injury Rehabilitation. A Certified Specialist in the Pilates Method, he has been the owner, technical director, and instructor at Pilates Studio el Patio, a Pilates and rehabilitation center in Madrid, Spain, since 2005.
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