Journal of Bodywork & Movement Therapies (2014) 18, 34e41
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/jbmt
EXERCISE PHYSIOLOGY
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises Denise Martineli Rossi, PT, MSc a,*, Mary Hellen Morcelli, PT, MSc, Ph.D a, Nise Ribeiro Marques, PT, MSc, Ph.D a, ¸alves, PT, Camilla Zamfolini Hallal, PT, MSc, Ph.D a, Mauro Gonc a b Ph.D , Dain P. LaRoche, BExSc, Ph.D , Marcelo Tavella Navega, PT, Ph.D c a
Department of Physical Education, Sa˜o Paulo State University, Rio Claro, Brazil Department of Kinesiology, University of New Hampshire, Durham, NC, USA c Department of Physical Therapy and Occupational Therapy, Sa˜o Paulo State University, Marı´lia, Brazil b
Received 6 September 2012; received in revised form 9 April 2013; accepted 11 April 2013
KEYWORDS Electromyography; Stability; Pilates method; Physiotherapy
Summary The purpose of this study was to compare the antagonist coactivation of the local and global trunk muscles during mat-based exercises of Skilled Modern Pilates. Twelve women performed five exercises and concurrently, surface EMG from internal oblique (OI), multifidus (MU), rectus abdominis (RA) and iliocostalis lumborum (IL) muscles was recorded bilaterally. The percentage of antagonist coactivation between local (OI/MU) and global muscles (RA/IL) was calculated. Individuals new to the practice of these exercises showed differences in coactivation of the trunk muscles between the exercises and these results were not similar bilaterally. Thus, in clinical practice, the therapist should be aware of factors such as compensation and undesirable rotation movements of the trunk. Moreover, the coactivation of global muscles was higher bilaterally in all exercises analyzed. This suggests that the exercises of Skilled Modern Pilates only should be performed after appropriate learning and correct execution of all principles, mainly the Centering Principle. ª 2013 Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: þ55 19 3526 4345. E-mail address: [email protected] (D.M. Rossi). 1360-8592/$ - see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jbmt.2013.04.006
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
Introduction The Pilates Method is a kinesiotherapeutic technique widely used by therapists that was created during the First World War by Joseph Pilates. The prescription and composition of the exercises was based on his experience with the rehabilitation of injured people (Loss et al., 2010). This method is based on six principles: concentration, control, flowing, precision, breathing and the centering principle, considered a differential technique of the method (Gladwell et al., 2006). The Centering Principle consists of an isometric contraction of the internal oblique and transverse abdominis muscles, which contributes to increased antagonist coactivation of the deep lumbar muscles (Marques et al., 2012). Currently, the Pilates Method has been widely applied in physiotherapy for flexibility training, stimulation of blood circulation, improvement of postural alignment and body awareness (Muscolino and Cipriani, 2004). The exercises challenge the stability of the trunk and activate the deep muscles of the lumbo-pelvic region (multifidus, internal oblique and transversus abdominis), and require endurance of trunk muscles (rectus abdominis, iliocostalis lumborum and latissimus dorsi) (Endleman and Critchley, 2008). Thus, the Pilates Method has been used for both prevention and rehabilitation of low back pain (Muscolino and Cipriani, 2004; Endleman and Critchley, 2008). Low back pain is a common musculoskeletal symptom in modern society that results in significant costs to healthcare systems. It is estimated that 90% of cases of low back pain have a nonspecific origin, so this condition has a multifactorial and complex etiology (Ebenbichler et al., 2001). Among the possible causes of nonspecific low back pain are muscle dysfunctions, changes in motor control and inadequate recruitment of trunk muscles, which lead to reduced stability of the segments of the spine and altered distribution of loads in this region (Ebenbichler et al., 2001). Recently, Skilled Modern Pilates has been proposed as an adaptation of the traditional Pilates Method which has been widely applied in physiotherapy. This new approach to the Pilates Method uses the philosophy created by Joseph Pilates, but decreases the range of motion of the exercises and requires a neutral lumbar-pelvic posture (Latey, 2001, 2002). Neutral lumbar-pelvic posture is more adapted to the physiological curvature of the lumbar spine and also provides an optimal position to increases the recruitment of deep lumbar and abdominal muscles (Sapsford et al., 2001; O’Sullivan et al., 2006). According to O’Sullivan et al. (2006), in the lumbo-pelvic upright sitting posture, that is, neutral lordosis of the lumbar spine, the local muscles, multifidus and internal obliquus, had 62% and 30% higher activity (respectively) compared to an extended thoracolumbar spine posture, and 62% and 48% higher activity (respectively) compared to a relaxed thoracolumbar spine with a posteriorly rotated pelvis. Additionally, spinal stability is increased with the coactivation of the local trunk muscles and this strategy promotes protection of spine structures during the performance of functional activities (Arokoski et al., 2004). In this
35
regard, electromyography has proven to be an important tool to study the function of the neuromuscular system of the low back by quantifying the coactivation of antagonist muscle groups (Granata et al., 2005). The stability of the segments of the spine is provided by the interaction of three subsystems: active, composed by skeletal muscles surrounding the spine; passive, composed of vertebrae and their articular structures; and neural, composed of afferent, efferent, and central neural control mechanisms (Panjabi, 1992). In physiological conditions, these subsystems provide spinal stability, principally, with the recruitment of the trunk muscles, which provide dynamic stability (Panjabi, 2003). Moreover, it is suggested that the most widely used mechanism for the maintenance of spinal stability is the coactivation of trunk muscles, since this strategy promotes protection of spinal structures during the performance of functional activities. In this regard, electromyography has proven to be an important tool to study the function of the neuromuscular system of the low back by quantifying the coactivation of antagonist muscle groups (Granata et al., 2005). Studies of spinal stability point to structural differentiation of local and global trunk muscles based on their direct or indirect attachment to the vertebrae. The local muscles, such as multifidus (MU) and internal oblique (OI), despite having a limited capacity to generate torque, have insertions on the vertebrae, which contribute to control the movement of each lumbar vertebra. On the other hand, the global muscles, such as the rectus abdominis (RA) and the iliocostalis lumborum (IL), cross several joints with attachments to the pelvis and the thorax, have a larger moment arm, and are suited to the control of trunk orientation and the resistance of external forces (Bergmark, 1989; Hodges, 2003). In clinical practice, the largest recruitment of global muscles seems to be associated with an increase in spinal load that has the potential to cause injury or worsen pain in patients with low back pain (Arokoski et al., 2004). According to Arokoski et al. (2004) therapists should find more cautious exercises to challenge the local stabilizing muscles of the lumbar spine without placing an excessive load on the structures of this region. Thus, considering the importance of lumbopelvic and segmental spinal stability and the relationship to the trunk muscle response, the mat-based Skilled Modern Pilates exercises can be an alternative to improve conditioning and strength of trunk muscles without overloading the passive structures of the spine (Arokoski et al., 2004). In addition to focusing on the activation of local muscles, the Skilled Modern Pilates exercises are performed in a neutral position that leads to greater local muscle recruitment than global recruitment (O’Sullivan et al., 2006). Also, these exercises can be considered functional since they require the recruitment and sensoriomotor control of the trunk muscles while performing limb movements (Menacho et al., 2010). To our knowledge, no study had investigated the differential activation of local and global trunk muscles during these exercises. Therefore, the purpose of this study was to compare the antagonist coactivation of the local and global muscles during several mat-based Skilled Modern Pilates exercises to ascertain which exercises stimulate
36
D.M. Rossi et al.
local muscle coactivation most. From the principles of Pilates, we hypothesized that during the execution of the exercises in a neutral posture, the local muscle antagonist coactivation would be higher than the global muscle antagonist coactivation to minimize the disturbance of vertebral segments created by upper and lower limb movements.
Methods Subjects This cross-sectional study utilized twelve, young women, recruited from the university who were physically active with no previous experience with Pilates exercise (Table 1). From a pilot study conducted in our laboratory, sample size was estimated by considering a standardized effect size of 1.2 with alpha error of 0.05 to find differences in the activation of local and global muscles bilaterally during the Hundreds (level I) exercise. Subjects were excluded for orthopedic disorders, neurological problems, cardiovascular disease, or previous surgery of the spine or abdomen. This study was approved by the Local Ethics committee (case number 067/2009), and all volunteers signed an informed consent.
Procedures Data collection was performed during two different sessions. On the first day, weight, height, body mass index, age and physical activity level were recorded. Also, the volunteers were familiarized with the Skilled Modern Pilates Method principles and they practiced all the exercises performed during the data collection day using the same protocol. On the second day, the subjects performed a single trial of each of the five exercises including, Hundreds level I (HU I), Hundreds level II (HU II), One Leg Stretch level I (OLS I), One Leg Stretch II (OLS II) and Scissors level I (SC I), in random order. All exercises were supervised by a physiotherapist with experience in the Pilates Method. Concurrently, surface EMG from OI, MU, RA and IL was recorded bilaterally.
Exercises The volunteers were taught to recruit their deep abdominal muscles using a variety of strategies, including visual imagery, verbal cueing and demonstration. Moreover the conscious recruitment of the deep abdominal muscles and the incorporation of the Pilates principles of breathing Table 1 Means of body anthropometrics, age and physical activity level of the subjects (n Z 12). Mean (SD) Mass (kg) Height (m) Body mass index (kg$m2) Age (years) Physical activity level (hours/week)
56.74 (7.7) 1.62 (0.06) 21.57 (2.3) 20.05(2.5) 5.54 (1.91)
control and neutral spinal alignment were taught and encouraged during the exercises. The neutral position was defined as the intermediate position between lumbar spine retroversion and anteversion and was maintained and monitored during the exercises by a barometric system specially developed for the study. This was a simple device composed of a bag that was inflated under the back of the volunteers which required them to maintain a certain pressure (and thus position), with a tolerance of 10 mmHg. The device was used to ensure quality and precision in exercise performance by testing and monitoring the position of the low back as a control for the evaluator and also to provide feedback to the subjects about the contraction of the abdominal muscles. Prior to execution of the exercises, the subjects were placed in an initial position lying supine with their knees flexed at 45 , feet aligned in the sagittal plane with the ischial tuberosity, the lumbar spine in a neutral position, and the arms extended alongside the body. From this starting position, the five exercises were performed, HU I, HU II, OLS I, OLS II and SC I, during which the electromyographic signal of the local and global muscles of the trunk were recorded. The HU I exercise was performed with the subjects in the supine position, with the hips and knees flexed, while the feet remained flat on the floor and the upper limbs were held alongside the body. Subjects were instructed to perform low amplitude shoulder flexion of both upper limbs with the hands held approximately 15 cm above the floor (Fig. 1A). The HU II exercise involved the same shoulder position as HU I, but simultaneously required the subjects to hold the dominant hip and knee flexed at 90 (Fig. 1B). In the OLS I exercise the subjects performed only lower-limb movements. Starting from the initial flexed position with feet on the ground, the subject performed controlled hip and knee extensions, lowering the leg until contact with the ground, one leg at a time (Fig. 1C). In the OLS II exercise, the subjects started from the initial position with both hips and knee flexed at 90 with the feet off the ground, and then the subjects unilaterally extended the knee and hip, while keeping the feet off the ground, returning to the initial position, which was then repeated with the other leg (Fig. 1D). In the SC I exercise the subjects started with the knee and hip flexed at 90 bilaterally with both feet off the ground. They then touched the toe to the ground, alternating feet, while keeping the contralateral lower limb suspended (Fig. 1D).
Electromyography The surface EMG signal was collected during the exercises using an eight-channel telemetry system (Noraxon Scottsdale, Arizona, USA) and was recorded with Myoresearch software (Noraxon), with a sampling frequency of 2000 Hz and a total gain of 2000 times (20 times in the sensor and 100 times in the equipment). The signal was recorded using Ag/AgCl surface electrodes (Miotec, Porto Alegre, Brazil), placed in bipolar configurations, with a recording area of 1 cm in diameter and interelectrode distance of 2 cm. Prior to electrode placement, the skin was carefully shaved and cleaned with alcohol to reduce resistance (Gonc ¸alves et al., 2012).
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
Figure 1
37
A: Hundreds level I; B: Hundreds level II; C: One Leg Stretch level I; D: One Leg Stretch level II and E: Scissors level I.
The electrodes were placed bilaterally on the muscles as follows: OI, 2 cm medial and inferior to the superior anterior iliac spine; MU, 2 cm lateral to the midline of the interspinous space L4-L5; RA, 3 cm above of the umbilicus and 2 cm lateral to the midline; IL, 6 cm lateral of the intervertebral space L2-L3. A reference electrode was positioned over the styloid process of the ulna on the right arm (Hermens et al., 2000; Marshall and Murphy, 2003; Marques et al., 2012).
Data analysis EMG signal analysis was carried out using specific routines developed in Matlab (Mathworks Natick, USA). The EMG signal was full-wave rectified and smoothed using a 4th order low-pass filter with a cut off frequency of 10 Hz. The linear envelope EMG data from each muscle, of each participant, was used to calculate the level of coactivation. For this analysis, the area under the signal amplitude curve was determined for the OI, MU, RA and IL muscles and the percentage of agonist/antagonist coactivation (% COCON) for the local muscles OI/MU and global muscles RA/IL was calculated using the following equation (Candotti et al., 2009): % COCON Z
2 common area AB 100 area A þ area B
where % COCON is the percent coactivation between two antagonist muscles, area A is the area below the smoothed EMG curve of muscle A, area B the area below the smoothed EMG curve of muscle B, common area A & B is the common area of activity of muscles A and B (Candotti et al., 2009).
Statistical analysis The PASW 18.0 statistical package (SPSS Inc.) was used to perform the statistical analysis. Comparisons were made for percentage coactivation between local and global muscles for the five exercises using repeated measures analysis of variance.
Comparisons were made between percentage coactivation between two local antagonist muscles (OI/MU) and two global antagonist muscles of the trunk (RA/IL) as for the five exercises using repeated measures analysis of variance (ANOVA) for the right and left sides of the body separately. This resulted in a 2 (local vs. global) 5 (exercises) analysis for each side of the body. Post hoc tests were performed using the Least Significant Difference (LSD) statistic to show which exercise had higher antagonist coactivation. Statistical significant was set at p < 0.05 for all tests.
Results Table 2 describes the repeated measures ANOVA results of the %COCON of the local antagonist muscles (OI/MU) and global antagonist muscles (RA/IL) in the five exercises analyzed, for the right and left sides of the body. On the right side, there was a significant difference for the coactivation between the exercises (f Z 5.145 and P Z 0.002) and between the local and global antagonist coactivation (f Z 31.966 and P < 0.0001). On the left side, there was a difference only for the %COCON between local (OI/MU) and
Table 2 Repeated measures analysis of variance results for comparison of local and global antagonist coactivation in five exercises analyzed for the right and left side.
Exercises Dof: 4 Local/global Dof: 1 Exercises local/ global Dof: 4 *p < 0.05.
Right
Side
Left
Side
f
P
f
p
5. 145
0. 002*
1. 645
31. 966
0. 0001*
37. 336
0. 198
0. 624
0. 753
0. 180 0. 0001* 0. 753
38
D.M. Rossi et al.
Figure 2 (a) Comparison of the local and global %COCON on the right side; (b) Comparison of the local and global %COCON on the left side. y Z significant difference between global (RA/IL) and local (IO/MU) %COCON.
global (RA/IL) antagonist muscles (f Z 37.366 and P < 0.001). For both sides, there was no significant difference in the interaction of exercise and antagonist coactivation. For the right side, global %COCON (RA/IL) was 52.01% higher than local %COCON (IO/MU) (Fig. 2a) and for the left side global %COCON was 45.46% higher than local %COCON (Fig. 2b). Additionally, HU I exercise had 19.99% and 22.32% higher coactivation than OLS I (p Z 0.057) and SC I (p Z 0.013); and HU II had 19.45%, 15.47% and 21.87% higher coactivation than OLS I (p Z 0.032); OLS II (p Z 0.058) and SC I (p Z 0.011; Fig. 3).
Discussion Due to the significance of the Pilates Method to the clinical population with low back pain, is important to study the
antagonist coactivation of the trunk muscles, particularly with respect to the potential vertebral overload during these exercises. Activation of trunk muscles has been described as one of the mechanisms used to maintain spinal stability and provide protection to structures. This is particularly the case for the local spinal muscles used to minimize the disturbance of the vertebral segments created by movements of the upper and lower limbs (Granata et al., 2005). From the principles of the Pilates Method, which aim to activate the deep muscles of the lumbo-pelvic region, the initial hypothesis of this study was that during the exercises in neutral lumbar spinal alignment, the antagonist coactivation of the local muscles would be higher compared to global muscles. In this study, the comparison of antagonist coactivation of the trunk muscles during mat-based Skilled Modern Pilates exercises demonstrated that for the right side, the
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
39
Figure 3 Comparison of the coactivation between the exercises on the right side. * Z significant difference between HU I Z Hundreds level I and OLS I Z One Leg Stretch level I; £ Z significant difference between HU I and SC I Z Scissors level I; x Z significant difference between HU II Z Hundreds level II and OLS I; U Z significant difference between HU II and OLS II Z One Leg Stretch level II; z Z significant difference between HU II and SC I Z Scissors level I.
HU I and HU II exercises had higher antagonist coactivation. In contrast to our findings, Souza et al. (2001) found no difference in EMG activity between the right and left sides during the execution of exercises for spinal segmental stabilization. Our results may be related to possible compensation in the trunk muscle activation to maintain stability during the execution of the exercises. The asymmetry of the load application from the weight of the lower limbs during the execution of the unilateral exercises generates disturbance and trunk rotation which may have led to higher coactivation of trunk musculature on the right side. Also, the fact that all the subjects of the sample were right-handed should also be considered. When investigating the EMG coactivation of the global and local trunk muscles, in contrast to the initial hypothesis, this study found that on both sides of the body, antagonist coactivation of the global muscles, RA and IL, was higher in all exercises. The anterior and posterior muscles of the trunk, like RA and IL, play important roles in maintaining the stability of the vertebral column. Because they are considered histological and anatomically as global muscles, they are functionally responsible for generating the torque required to move the trunk and limbs and to transfer the external loads to minimize overload of the spine (Hodges, 2003). During the execution of OLS level I and II and SC level I exercises, alternating movements of the lower limbs in both closed kinetic chain (OLS I) and open kinetic chain (OLS II and SC I) exercises were performed. There is a relationship between increased antagonist coactivation of the trunk muscles, the asymmetric load applied, and the length of the lever arm (McCook et al., 2009). The local muscles, MU and OI, act to “fine tune” intervetebral movements and generate shear forces during changes in the position of the trunk. The global muscles, RA and IL, are fundamental to pelvic stability during exercises with knee extension and also work to control the torque generated by hip extension (Hodges, 2003). Thus, it can be inferred that besides the need to maintain spinal stability and the
neutral position of the lumbar spine, the highest global antagonist coactivation of the trunk muscles was necessary for the production of flexor torque as a result of dynamic alternation of leg movements and the long lever arm of the lower limb (Hodges, 2003; McCook et al., 2009). The control of joint and spinal stability depends directly on the active system coordinated by the contraction of muscles. The stability of the system is provided by the necessary stiffness to appropriately restrict movement. In the spine, the compressive forces caused by the tension of passive structures and muscle action in the joints provide stiffness and stability. The stabilization of the lumbar spine is significantly increased by the tension applied by the local and global muscles in the thoracolumbar fascia (Van dieen et al., 2003a, b; Reeves et al., 2007). According to Van dieen et al. (2003a,b) the direction of the external perturbation forces is the main factor that will determine which trunk muscles are recruited to stabilize the spine. Furthermore, despite histological, anatomical, and functional differences, the stability of the column is provided by all the trunk muscles. Thus, the system continuously adjusts the stiffness of the column to generate the stability required of certain tasks, and the force and movement characteristics of the task determine which muscles are more active (Van dieen et al., 2003a, b, Reeves et al., 2007). Pilates exercises are used for spinal stabilization and have been widely used to treat low back pain (Arokoski et al., 2004). It has been shown that the maintenance of postural alignment during the exercises stimulates the activation of stabilizing muscles, such as the internal oblique, transversus abdominis and multifidus muscles (Colado et al., 2011). In the initial phase of rehabilitation, contemporary approaches involve the recruitment of abdominal muscles such as transversus abdominis (TrA) and OI, with minimal activity of the superficial abdominal muscles. These practices are based on evidence that individuals with low back pain have dysfunction of these muscles and exercises that aim to improve the recruitment
40 of these muscles will contribute to vertebral control. Furthermore, these treatments focus on low-level contraction, as it has been suggested that low levels of contraction are sufficient to provide the stiffness required for control of the intervertebral joints (Urquhart et al., 2005). However, despite the known beneficial effects of these exercises, such as reduced intensity of pain and dysfunction, there is insufficient scientific and clinical evidence of how the actions of the muscles stabilizing the spine change during the execution of the exercises (Arokoski et al., 2004; Critchley et al., 2011). This study examined a sample that did not report back pain, however, there is evidence that exercise therapy produces lower activity of trunk muscles in subjects with low back pain compared with subjects who never had a previous painful episode (Arokoski et al., 2004). In clinical practice, the increased recruitment of global muscles seems to be associated with increased spinal load that can cause injury or worsen the pain in individuals with low back pain (Arokoski et al., 2004). Although the recruitment of local muscles is emphasized in the initial phase of rehabilitation, all the muscles of the trunk are considered important for the restoration of normal function and the progression of exercises involves strategies for the rehabilitation of the muscular system of the trunk as a whole (Arokoski et al., 2004; Urquhart et al., 2005).
Conclusion Individuals new to the practice of the mat-based Skilled Modern Pilates exercises showed differences in coactivation of the trunk muscles between the exercises. These results weren’t similar between the sides of the body, because for only the right side, the HU I and HU II exercises had higher antagonist coactivation. Therefore, in clinical practice, the physiotherapist should be aware of factors such as compensation for weak muscles by one side of the body that may result in undesirable rotation movements of the trunk. Furthermore, the antagonist coactivation of global muscles was higher than local muscles in all of the exercises and it seems that this is associated with increased spinal load. Thus, these exercises should be performed after appropriate learning of the movements and correct execution of the Pilates principles, mainly the Centering Principle, which is to activate the local stabilizing muscles to avoid overloading the spine.
Limitations A limitation of this study is that the protocol was performed in a single attempt and results may have differed if the exercises were performed on separate days. Additional information of how muscle activation is controlled during the exercises could have been made if the activity of other muscles had been studied, such as the external obliques and stabilizers of the hip. LSD post hoc tests were used to increase the statistical power due a relatively small sample size. Therefore, these initial findings should be interpreted cautiously and the study should be replicated. Another study limitation is that the volunteers were novices and had no experience with the Pilates Method, and the muscle
D.M. Rossi et al. activation response may be different in those familiar with the exercises. Additional research should be conducted to study the activation of trunk muscles in people who routinely perform Pilates exercises to understand the effect of training on trunk stabilizer muscle activation.
Conflict of interest statement None.
Acknowledgements D.M. Rossi was supported by Coordenac ¸˜ ao de Aperfeic ¸oamento de Pessoal de Nı´vel Superior (CAPES).
References Arokoski, J.P., Valta, T., Kankaanpa, M., Airaksinen, O., 2004. Activation of lumbar paraspinal iand abdominal muscles during therapeutic exercises in chronic low back pain patients. Archives of Physical Medicine and Rehabilitation 85, 823e832. Bergmark, A., 1989. Stability of the lumbar spine: a study in mechanical engineering. Acta Orthopaedica Scandinavica 60, 4e54. Candotti, C.T., Loss, J.F., Bagatini, D., Soares, D.P., Rocha, E.K., Oliveira, A.R., Guimara ˜es, A.C.S., 2009. Cocontraction and economy of triathletes and cyclists at different cadences during cycling motion. Journal of Electromyography and Kinesiology 19, 915e921. Colado, J.C., Pablos, C., Chulvi-Medrano, I., Garcia-Masso, X., Flandez, J., Behm, D.G., 2011. The progression of paraspinal muscle recruitment intensity in localized and global strength training exercises is not based on instability alone. Archives of Physical Medicine and Rehabilitation 92, 1875e1883. Critchley, D.J., Pierson, Z., Battersby, G., 2011. Effect of the Pilates mat exercises and conventional exercise programmes on transverses abdominis and obliquus internus abdominis activity: pilot randomized trial. Manual Therapy 16, 183e189. Ebenbichler, G.R., Oddsson, L.I., Kollmitzer, J., Erim, Z., 2001. Sensory-motor control of the lower back implications for rehabilitation. Medicine and Science in Sports and Exercise 33 (11), 1889e1898. Endleman, I., Critchley, D.J., 2008. Transversus abdominis and obliquus internus activity during Pilates exercises: measurement with ultrasound scanning. Archives of Physical Medicine and Rehabilitation 89, 2205e2212. Gladwell, V., Head, S., Haggar, M., Beneke, R., 2006. Does a program of the Pilates improve chronic non-specific low back pain? Journal Sport Rehabilitation 15, 338e350. Gonc ¸alves, M., Marques, N.R., Hallal, C.Z., Van Dieen, J.H., 2012. Electromyographic activity of trunk muscles during exercises with flexible and non-flexible poles. Journal of Back and Musculoskeletal Rehabilitation 24, 209e214. Granata, K., Lee, P.E., Franklin, T.C., 2005. Co-contraction recruitment and spinal load during isometric trunk flexion and extension. Clinical Biomechanics 20 (10), 1029e1037. Hermens, J.H., Freriks, B., Disselhorst-Klug, C., Rau, G., 2000. Development of recommendations for SEMG sensors and sensor placement procedures. Journal of Electromyography and Kinesiology 10, 361e374. Hodges, P.W., 2003. Core stability exercise in chronic low back pain. Orthopedic Clinics of North America 34, 245e254. Latey, P., 2002. Updating the principles of the Pilates Method: part 2. Journal of Bodywork Movement Therapies 6 (2), 94e101. Latey, P., 2001. The Pilates Method: history and philosophy. Journal of Bodywork and Movement Therapies 5 (4), 275e282.
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises Loss, J.F., Melo, M.O., Rosa, C.H., Santos, A.B., La Torre, M., Silva, Y.O., 2010. Eletrical activity of external obliqu ´e and multifidus muscles during hip flexion-extension exercise performed in the Cadillac with different adjustments of springs and individual positions. Revista Brasileira de Fisioterapia 14 (6), 510e517. Marques, N.R., Morcelli, M.H., Hallal, N.R., Gonc ¸alves, M., 2012. EMG activity of trunk stabilizer muscles during Centering Principle of Pilates Method. Journal of Bodywork and Movements Therapies, Impress. Marshall, P., Murphy, B., 2003. The validity and reliability of surface EMG to assess the neuromuscular response of the abdominal muscles to rapid limb movement. Journal of Electromyography and Kinesiology 13, 477e489. McCook, D.T., Vicenzino, B., Hodges, P.W., 2009. Activity of deep abdominal muscles increases during submaximal flexion and extension efforts but antagonist co-contraction remains unchanged. Journal of Electromyography and Kinesiology 19, 754e762. Menacho, M.O., Obara, K., Conceic ¸˜ ao, J., Chitolina, M.L., Krantz, D.R., Silva, R.A., Cardoso, J.R., 2010. Electromyographic effect of mat Pilates exercise on the muscle activity of the healthy adult females. Journal of Manipulative and Physiological Therapeutics 33 (9), 672e678. Muscolino, J.E., Cipriani, S., 2004. Pilates and the powerhouse-II. Journal of Bodywork and Movement Therapies 8, 122e130. O’Sullivan, P., Dankaerts, W., Burnett, A.F., Farrel, G.T., Jefford, E., Naylor, C.S., 2006. Effect of different upright postures on spinal-pelvic curvature and trunk muscle activation in a pain free population. Spine 31 (19), E707eE712.
41
Panjabi, M.M., 1992. The stabilizing of the spine. Part I. Function, dysfunction, adaptation and enhancement. Journal of Spinal Disorders 5 (4), 383e389. Panjabi, M.M., 2003. Clinial spinal instability and low back pain. Journal of Electromyography and Kinesiology 13, 371e379. Reeves, N.P., Narendra, K.S., Cholewicki, J., 2007. Spine stability: six blind men 493 and the elephant. Clinical Biomechanics 22, 266e274. Sapsford, R.R., Hodges, P.W., Richardson, C.A., Cooper, D.H., Markewell, S.J., Jull, G.A., 2001. Co-activation of the abdominal and pelvic floor muscles during voluntary exercises. Neurology & Urodynamics 20 (1), 31e42. Souza, G.M., Baker, L.L., Powers, C.M., 2001. Eletromyographic activity of selected trunk muscles during dynamic spine stabilization exercises. Archives of Physical Medicine and Rehabilitation 82, 86e92. Urquhart, D.M., Hodges, P.W., Allen, T.J., Story, I.H., 2005. Abdominal muscle recruitment during a range of voluntary exercises. Manual Therapy 10, 144e153. Van dieen, J., Kingma, I., Van Der Gub, J.C.E., 2003a. Evidence for a role of antagonistic cocontraction in controlling trunk stiffness during lifting. Journal of Biomechanics 36, 1829e1836. Van dieen, J.H., Cholewicki, J., Radebold, A., 2003b. Trunk muscle recruitment patterns in patients with low back enhance the stability of lumbar spine. Spine 28, 834e841.
Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/jbmt
EXERCISE PHYSIOLOGY
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises Denise Martineli Rossi, PT, MSc a,*, Mary Hellen Morcelli, PT, MSc, Ph.D a, Nise Ribeiro Marques, PT, MSc, Ph.D a, ¸alves, PT, Camilla Zamfolini Hallal, PT, MSc, Ph.D a, Mauro Gonc a b Ph.D , Dain P. LaRoche, BExSc, Ph.D , Marcelo Tavella Navega, PT, Ph.D c a
Department of Physical Education, Sa˜o Paulo State University, Rio Claro, Brazil Department of Kinesiology, University of New Hampshire, Durham, NC, USA c Department of Physical Therapy and Occupational Therapy, Sa˜o Paulo State University, Marı´lia, Brazil b
Received 6 September 2012; received in revised form 9 April 2013; accepted 11 April 2013
KEYWORDS Electromyography; Stability; Pilates method; Physiotherapy
Summary The purpose of this study was to compare the antagonist coactivation of the local and global trunk muscles during mat-based exercises of Skilled Modern Pilates. Twelve women performed five exercises and concurrently, surface EMG from internal oblique (OI), multifidus (MU), rectus abdominis (RA) and iliocostalis lumborum (IL) muscles was recorded bilaterally. The percentage of antagonist coactivation between local (OI/MU) and global muscles (RA/IL) was calculated. Individuals new to the practice of these exercises showed differences in coactivation of the trunk muscles between the exercises and these results were not similar bilaterally. Thus, in clinical practice, the therapist should be aware of factors such as compensation and undesirable rotation movements of the trunk. Moreover, the coactivation of global muscles was higher bilaterally in all exercises analyzed. This suggests that the exercises of Skilled Modern Pilates only should be performed after appropriate learning and correct execution of all principles, mainly the Centering Principle. ª 2013 Elsevier Ltd. All rights reserved.
* Corresponding author. Tel.: þ55 19 3526 4345. E-mail address: [email protected] (D.M. Rossi). 1360-8592/$ - see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jbmt.2013.04.006
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
Introduction The Pilates Method is a kinesiotherapeutic technique widely used by therapists that was created during the First World War by Joseph Pilates. The prescription and composition of the exercises was based on his experience with the rehabilitation of injured people (Loss et al., 2010). This method is based on six principles: concentration, control, flowing, precision, breathing and the centering principle, considered a differential technique of the method (Gladwell et al., 2006). The Centering Principle consists of an isometric contraction of the internal oblique and transverse abdominis muscles, which contributes to increased antagonist coactivation of the deep lumbar muscles (Marques et al., 2012). Currently, the Pilates Method has been widely applied in physiotherapy for flexibility training, stimulation of blood circulation, improvement of postural alignment and body awareness (Muscolino and Cipriani, 2004). The exercises challenge the stability of the trunk and activate the deep muscles of the lumbo-pelvic region (multifidus, internal oblique and transversus abdominis), and require endurance of trunk muscles (rectus abdominis, iliocostalis lumborum and latissimus dorsi) (Endleman and Critchley, 2008). Thus, the Pilates Method has been used for both prevention and rehabilitation of low back pain (Muscolino and Cipriani, 2004; Endleman and Critchley, 2008). Low back pain is a common musculoskeletal symptom in modern society that results in significant costs to healthcare systems. It is estimated that 90% of cases of low back pain have a nonspecific origin, so this condition has a multifactorial and complex etiology (Ebenbichler et al., 2001). Among the possible causes of nonspecific low back pain are muscle dysfunctions, changes in motor control and inadequate recruitment of trunk muscles, which lead to reduced stability of the segments of the spine and altered distribution of loads in this region (Ebenbichler et al., 2001). Recently, Skilled Modern Pilates has been proposed as an adaptation of the traditional Pilates Method which has been widely applied in physiotherapy. This new approach to the Pilates Method uses the philosophy created by Joseph Pilates, but decreases the range of motion of the exercises and requires a neutral lumbar-pelvic posture (Latey, 2001, 2002). Neutral lumbar-pelvic posture is more adapted to the physiological curvature of the lumbar spine and also provides an optimal position to increases the recruitment of deep lumbar and abdominal muscles (Sapsford et al., 2001; O’Sullivan et al., 2006). According to O’Sullivan et al. (2006), in the lumbo-pelvic upright sitting posture, that is, neutral lordosis of the lumbar spine, the local muscles, multifidus and internal obliquus, had 62% and 30% higher activity (respectively) compared to an extended thoracolumbar spine posture, and 62% and 48% higher activity (respectively) compared to a relaxed thoracolumbar spine with a posteriorly rotated pelvis. Additionally, spinal stability is increased with the coactivation of the local trunk muscles and this strategy promotes protection of spine structures during the performance of functional activities (Arokoski et al., 2004). In this
35
regard, electromyography has proven to be an important tool to study the function of the neuromuscular system of the low back by quantifying the coactivation of antagonist muscle groups (Granata et al., 2005). The stability of the segments of the spine is provided by the interaction of three subsystems: active, composed by skeletal muscles surrounding the spine; passive, composed of vertebrae and their articular structures; and neural, composed of afferent, efferent, and central neural control mechanisms (Panjabi, 1992). In physiological conditions, these subsystems provide spinal stability, principally, with the recruitment of the trunk muscles, which provide dynamic stability (Panjabi, 2003). Moreover, it is suggested that the most widely used mechanism for the maintenance of spinal stability is the coactivation of trunk muscles, since this strategy promotes protection of spinal structures during the performance of functional activities. In this regard, electromyography has proven to be an important tool to study the function of the neuromuscular system of the low back by quantifying the coactivation of antagonist muscle groups (Granata et al., 2005). Studies of spinal stability point to structural differentiation of local and global trunk muscles based on their direct or indirect attachment to the vertebrae. The local muscles, such as multifidus (MU) and internal oblique (OI), despite having a limited capacity to generate torque, have insertions on the vertebrae, which contribute to control the movement of each lumbar vertebra. On the other hand, the global muscles, such as the rectus abdominis (RA) and the iliocostalis lumborum (IL), cross several joints with attachments to the pelvis and the thorax, have a larger moment arm, and are suited to the control of trunk orientation and the resistance of external forces (Bergmark, 1989; Hodges, 2003). In clinical practice, the largest recruitment of global muscles seems to be associated with an increase in spinal load that has the potential to cause injury or worsen pain in patients with low back pain (Arokoski et al., 2004). According to Arokoski et al. (2004) therapists should find more cautious exercises to challenge the local stabilizing muscles of the lumbar spine without placing an excessive load on the structures of this region. Thus, considering the importance of lumbopelvic and segmental spinal stability and the relationship to the trunk muscle response, the mat-based Skilled Modern Pilates exercises can be an alternative to improve conditioning and strength of trunk muscles without overloading the passive structures of the spine (Arokoski et al., 2004). In addition to focusing on the activation of local muscles, the Skilled Modern Pilates exercises are performed in a neutral position that leads to greater local muscle recruitment than global recruitment (O’Sullivan et al., 2006). Also, these exercises can be considered functional since they require the recruitment and sensoriomotor control of the trunk muscles while performing limb movements (Menacho et al., 2010). To our knowledge, no study had investigated the differential activation of local and global trunk muscles during these exercises. Therefore, the purpose of this study was to compare the antagonist coactivation of the local and global muscles during several mat-based Skilled Modern Pilates exercises to ascertain which exercises stimulate
36
D.M. Rossi et al.
local muscle coactivation most. From the principles of Pilates, we hypothesized that during the execution of the exercises in a neutral posture, the local muscle antagonist coactivation would be higher than the global muscle antagonist coactivation to minimize the disturbance of vertebral segments created by upper and lower limb movements.
Methods Subjects This cross-sectional study utilized twelve, young women, recruited from the university who were physically active with no previous experience with Pilates exercise (Table 1). From a pilot study conducted in our laboratory, sample size was estimated by considering a standardized effect size of 1.2 with alpha error of 0.05 to find differences in the activation of local and global muscles bilaterally during the Hundreds (level I) exercise. Subjects were excluded for orthopedic disorders, neurological problems, cardiovascular disease, or previous surgery of the spine or abdomen. This study was approved by the Local Ethics committee (case number 067/2009), and all volunteers signed an informed consent.
Procedures Data collection was performed during two different sessions. On the first day, weight, height, body mass index, age and physical activity level were recorded. Also, the volunteers were familiarized with the Skilled Modern Pilates Method principles and they practiced all the exercises performed during the data collection day using the same protocol. On the second day, the subjects performed a single trial of each of the five exercises including, Hundreds level I (HU I), Hundreds level II (HU II), One Leg Stretch level I (OLS I), One Leg Stretch II (OLS II) and Scissors level I (SC I), in random order. All exercises were supervised by a physiotherapist with experience in the Pilates Method. Concurrently, surface EMG from OI, MU, RA and IL was recorded bilaterally.
Exercises The volunteers were taught to recruit their deep abdominal muscles using a variety of strategies, including visual imagery, verbal cueing and demonstration. Moreover the conscious recruitment of the deep abdominal muscles and the incorporation of the Pilates principles of breathing Table 1 Means of body anthropometrics, age and physical activity level of the subjects (n Z 12). Mean (SD) Mass (kg) Height (m) Body mass index (kg$m2) Age (years) Physical activity level (hours/week)
56.74 (7.7) 1.62 (0.06) 21.57 (2.3) 20.05(2.5) 5.54 (1.91)
control and neutral spinal alignment were taught and encouraged during the exercises. The neutral position was defined as the intermediate position between lumbar spine retroversion and anteversion and was maintained and monitored during the exercises by a barometric system specially developed for the study. This was a simple device composed of a bag that was inflated under the back of the volunteers which required them to maintain a certain pressure (and thus position), with a tolerance of 10 mmHg. The device was used to ensure quality and precision in exercise performance by testing and monitoring the position of the low back as a control for the evaluator and also to provide feedback to the subjects about the contraction of the abdominal muscles. Prior to execution of the exercises, the subjects were placed in an initial position lying supine with their knees flexed at 45 , feet aligned in the sagittal plane with the ischial tuberosity, the lumbar spine in a neutral position, and the arms extended alongside the body. From this starting position, the five exercises were performed, HU I, HU II, OLS I, OLS II and SC I, during which the electromyographic signal of the local and global muscles of the trunk were recorded. The HU I exercise was performed with the subjects in the supine position, with the hips and knees flexed, while the feet remained flat on the floor and the upper limbs were held alongside the body. Subjects were instructed to perform low amplitude shoulder flexion of both upper limbs with the hands held approximately 15 cm above the floor (Fig. 1A). The HU II exercise involved the same shoulder position as HU I, but simultaneously required the subjects to hold the dominant hip and knee flexed at 90 (Fig. 1B). In the OLS I exercise the subjects performed only lower-limb movements. Starting from the initial flexed position with feet on the ground, the subject performed controlled hip and knee extensions, lowering the leg until contact with the ground, one leg at a time (Fig. 1C). In the OLS II exercise, the subjects started from the initial position with both hips and knee flexed at 90 with the feet off the ground, and then the subjects unilaterally extended the knee and hip, while keeping the feet off the ground, returning to the initial position, which was then repeated with the other leg (Fig. 1D). In the SC I exercise the subjects started with the knee and hip flexed at 90 bilaterally with both feet off the ground. They then touched the toe to the ground, alternating feet, while keeping the contralateral lower limb suspended (Fig. 1D).
Electromyography The surface EMG signal was collected during the exercises using an eight-channel telemetry system (Noraxon Scottsdale, Arizona, USA) and was recorded with Myoresearch software (Noraxon), with a sampling frequency of 2000 Hz and a total gain of 2000 times (20 times in the sensor and 100 times in the equipment). The signal was recorded using Ag/AgCl surface electrodes (Miotec, Porto Alegre, Brazil), placed in bipolar configurations, with a recording area of 1 cm in diameter and interelectrode distance of 2 cm. Prior to electrode placement, the skin was carefully shaved and cleaned with alcohol to reduce resistance (Gonc ¸alves et al., 2012).
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
Figure 1
37
A: Hundreds level I; B: Hundreds level II; C: One Leg Stretch level I; D: One Leg Stretch level II and E: Scissors level I.
The electrodes were placed bilaterally on the muscles as follows: OI, 2 cm medial and inferior to the superior anterior iliac spine; MU, 2 cm lateral to the midline of the interspinous space L4-L5; RA, 3 cm above of the umbilicus and 2 cm lateral to the midline; IL, 6 cm lateral of the intervertebral space L2-L3. A reference electrode was positioned over the styloid process of the ulna on the right arm (Hermens et al., 2000; Marshall and Murphy, 2003; Marques et al., 2012).
Data analysis EMG signal analysis was carried out using specific routines developed in Matlab (Mathworks Natick, USA). The EMG signal was full-wave rectified and smoothed using a 4th order low-pass filter with a cut off frequency of 10 Hz. The linear envelope EMG data from each muscle, of each participant, was used to calculate the level of coactivation. For this analysis, the area under the signal amplitude curve was determined for the OI, MU, RA and IL muscles and the percentage of agonist/antagonist coactivation (% COCON) for the local muscles OI/MU and global muscles RA/IL was calculated using the following equation (Candotti et al., 2009): % COCON Z
2 common area AB 100 area A þ area B
where % COCON is the percent coactivation between two antagonist muscles, area A is the area below the smoothed EMG curve of muscle A, area B the area below the smoothed EMG curve of muscle B, common area A & B is the common area of activity of muscles A and B (Candotti et al., 2009).
Statistical analysis The PASW 18.0 statistical package (SPSS Inc.) was used to perform the statistical analysis. Comparisons were made for percentage coactivation between local and global muscles for the five exercises using repeated measures analysis of variance.
Comparisons were made between percentage coactivation between two local antagonist muscles (OI/MU) and two global antagonist muscles of the trunk (RA/IL) as for the five exercises using repeated measures analysis of variance (ANOVA) for the right and left sides of the body separately. This resulted in a 2 (local vs. global) 5 (exercises) analysis for each side of the body. Post hoc tests were performed using the Least Significant Difference (LSD) statistic to show which exercise had higher antagonist coactivation. Statistical significant was set at p < 0.05 for all tests.
Results Table 2 describes the repeated measures ANOVA results of the %COCON of the local antagonist muscles (OI/MU) and global antagonist muscles (RA/IL) in the five exercises analyzed, for the right and left sides of the body. On the right side, there was a significant difference for the coactivation between the exercises (f Z 5.145 and P Z 0.002) and between the local and global antagonist coactivation (f Z 31.966 and P < 0.0001). On the left side, there was a difference only for the %COCON between local (OI/MU) and
Table 2 Repeated measures analysis of variance results for comparison of local and global antagonist coactivation in five exercises analyzed for the right and left side.
Exercises Dof: 4 Local/global Dof: 1 Exercises local/ global Dof: 4 *p < 0.05.
Right
Side
Left
Side
f
P
f
p
5. 145
0. 002*
1. 645
31. 966
0. 0001*
37. 336
0. 198
0. 624
0. 753
0. 180 0. 0001* 0. 753
38
D.M. Rossi et al.
Figure 2 (a) Comparison of the local and global %COCON on the right side; (b) Comparison of the local and global %COCON on the left side. y Z significant difference between global (RA/IL) and local (IO/MU) %COCON.
global (RA/IL) antagonist muscles (f Z 37.366 and P < 0.001). For both sides, there was no significant difference in the interaction of exercise and antagonist coactivation. For the right side, global %COCON (RA/IL) was 52.01% higher than local %COCON (IO/MU) (Fig. 2a) and for the left side global %COCON was 45.46% higher than local %COCON (Fig. 2b). Additionally, HU I exercise had 19.99% and 22.32% higher coactivation than OLS I (p Z 0.057) and SC I (p Z 0.013); and HU II had 19.45%, 15.47% and 21.87% higher coactivation than OLS I (p Z 0.032); OLS II (p Z 0.058) and SC I (p Z 0.011; Fig. 3).
Discussion Due to the significance of the Pilates Method to the clinical population with low back pain, is important to study the
antagonist coactivation of the trunk muscles, particularly with respect to the potential vertebral overload during these exercises. Activation of trunk muscles has been described as one of the mechanisms used to maintain spinal stability and provide protection to structures. This is particularly the case for the local spinal muscles used to minimize the disturbance of the vertebral segments created by movements of the upper and lower limbs (Granata et al., 2005). From the principles of the Pilates Method, which aim to activate the deep muscles of the lumbo-pelvic region, the initial hypothesis of this study was that during the exercises in neutral lumbar spinal alignment, the antagonist coactivation of the local muscles would be higher compared to global muscles. In this study, the comparison of antagonist coactivation of the trunk muscles during mat-based Skilled Modern Pilates exercises demonstrated that for the right side, the
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises
39
Figure 3 Comparison of the coactivation between the exercises on the right side. * Z significant difference between HU I Z Hundreds level I and OLS I Z One Leg Stretch level I; £ Z significant difference between HU I and SC I Z Scissors level I; x Z significant difference between HU II Z Hundreds level II and OLS I; U Z significant difference between HU II and OLS II Z One Leg Stretch level II; z Z significant difference between HU II and SC I Z Scissors level I.
HU I and HU II exercises had higher antagonist coactivation. In contrast to our findings, Souza et al. (2001) found no difference in EMG activity between the right and left sides during the execution of exercises for spinal segmental stabilization. Our results may be related to possible compensation in the trunk muscle activation to maintain stability during the execution of the exercises. The asymmetry of the load application from the weight of the lower limbs during the execution of the unilateral exercises generates disturbance and trunk rotation which may have led to higher coactivation of trunk musculature on the right side. Also, the fact that all the subjects of the sample were right-handed should also be considered. When investigating the EMG coactivation of the global and local trunk muscles, in contrast to the initial hypothesis, this study found that on both sides of the body, antagonist coactivation of the global muscles, RA and IL, was higher in all exercises. The anterior and posterior muscles of the trunk, like RA and IL, play important roles in maintaining the stability of the vertebral column. Because they are considered histological and anatomically as global muscles, they are functionally responsible for generating the torque required to move the trunk and limbs and to transfer the external loads to minimize overload of the spine (Hodges, 2003). During the execution of OLS level I and II and SC level I exercises, alternating movements of the lower limbs in both closed kinetic chain (OLS I) and open kinetic chain (OLS II and SC I) exercises were performed. There is a relationship between increased antagonist coactivation of the trunk muscles, the asymmetric load applied, and the length of the lever arm (McCook et al., 2009). The local muscles, MU and OI, act to “fine tune” intervetebral movements and generate shear forces during changes in the position of the trunk. The global muscles, RA and IL, are fundamental to pelvic stability during exercises with knee extension and also work to control the torque generated by hip extension (Hodges, 2003). Thus, it can be inferred that besides the need to maintain spinal stability and the
neutral position of the lumbar spine, the highest global antagonist coactivation of the trunk muscles was necessary for the production of flexor torque as a result of dynamic alternation of leg movements and the long lever arm of the lower limb (Hodges, 2003; McCook et al., 2009). The control of joint and spinal stability depends directly on the active system coordinated by the contraction of muscles. The stability of the system is provided by the necessary stiffness to appropriately restrict movement. In the spine, the compressive forces caused by the tension of passive structures and muscle action in the joints provide stiffness and stability. The stabilization of the lumbar spine is significantly increased by the tension applied by the local and global muscles in the thoracolumbar fascia (Van dieen et al., 2003a, b; Reeves et al., 2007). According to Van dieen et al. (2003a,b) the direction of the external perturbation forces is the main factor that will determine which trunk muscles are recruited to stabilize the spine. Furthermore, despite histological, anatomical, and functional differences, the stability of the column is provided by all the trunk muscles. Thus, the system continuously adjusts the stiffness of the column to generate the stability required of certain tasks, and the force and movement characteristics of the task determine which muscles are more active (Van dieen et al., 2003a, b, Reeves et al., 2007). Pilates exercises are used for spinal stabilization and have been widely used to treat low back pain (Arokoski et al., 2004). It has been shown that the maintenance of postural alignment during the exercises stimulates the activation of stabilizing muscles, such as the internal oblique, transversus abdominis and multifidus muscles (Colado et al., 2011). In the initial phase of rehabilitation, contemporary approaches involve the recruitment of abdominal muscles such as transversus abdominis (TrA) and OI, with minimal activity of the superficial abdominal muscles. These practices are based on evidence that individuals with low back pain have dysfunction of these muscles and exercises that aim to improve the recruitment
40 of these muscles will contribute to vertebral control. Furthermore, these treatments focus on low-level contraction, as it has been suggested that low levels of contraction are sufficient to provide the stiffness required for control of the intervertebral joints (Urquhart et al., 2005). However, despite the known beneficial effects of these exercises, such as reduced intensity of pain and dysfunction, there is insufficient scientific and clinical evidence of how the actions of the muscles stabilizing the spine change during the execution of the exercises (Arokoski et al., 2004; Critchley et al., 2011). This study examined a sample that did not report back pain, however, there is evidence that exercise therapy produces lower activity of trunk muscles in subjects with low back pain compared with subjects who never had a previous painful episode (Arokoski et al., 2004). In clinical practice, the increased recruitment of global muscles seems to be associated with increased spinal load that can cause injury or worsen the pain in individuals with low back pain (Arokoski et al., 2004). Although the recruitment of local muscles is emphasized in the initial phase of rehabilitation, all the muscles of the trunk are considered important for the restoration of normal function and the progression of exercises involves strategies for the rehabilitation of the muscular system of the trunk as a whole (Arokoski et al., 2004; Urquhart et al., 2005).
Conclusion Individuals new to the practice of the mat-based Skilled Modern Pilates exercises showed differences in coactivation of the trunk muscles between the exercises. These results weren’t similar between the sides of the body, because for only the right side, the HU I and HU II exercises had higher antagonist coactivation. Therefore, in clinical practice, the physiotherapist should be aware of factors such as compensation for weak muscles by one side of the body that may result in undesirable rotation movements of the trunk. Furthermore, the antagonist coactivation of global muscles was higher than local muscles in all of the exercises and it seems that this is associated with increased spinal load. Thus, these exercises should be performed after appropriate learning of the movements and correct execution of the Pilates principles, mainly the Centering Principle, which is to activate the local stabilizing muscles to avoid overloading the spine.
Limitations A limitation of this study is that the protocol was performed in a single attempt and results may have differed if the exercises were performed on separate days. Additional information of how muscle activation is controlled during the exercises could have been made if the activity of other muscles had been studied, such as the external obliques and stabilizers of the hip. LSD post hoc tests were used to increase the statistical power due a relatively small sample size. Therefore, these initial findings should be interpreted cautiously and the study should be replicated. Another study limitation is that the volunteers were novices and had no experience with the Pilates Method, and the muscle
D.M. Rossi et al. activation response may be different in those familiar with the exercises. Additional research should be conducted to study the activation of trunk muscles in people who routinely perform Pilates exercises to understand the effect of training on trunk stabilizer muscle activation.
Conflict of interest statement None.
Acknowledgements D.M. Rossi was supported by Coordenac ¸˜ ao de Aperfeic ¸oamento de Pessoal de Nı´vel Superior (CAPES).
References Arokoski, J.P., Valta, T., Kankaanpa, M., Airaksinen, O., 2004. Activation of lumbar paraspinal iand abdominal muscles during therapeutic exercises in chronic low back pain patients. Archives of Physical Medicine and Rehabilitation 85, 823e832. Bergmark, A., 1989. Stability of the lumbar spine: a study in mechanical engineering. Acta Orthopaedica Scandinavica 60, 4e54. Candotti, C.T., Loss, J.F., Bagatini, D., Soares, D.P., Rocha, E.K., Oliveira, A.R., Guimara ˜es, A.C.S., 2009. Cocontraction and economy of triathletes and cyclists at different cadences during cycling motion. Journal of Electromyography and Kinesiology 19, 915e921. Colado, J.C., Pablos, C., Chulvi-Medrano, I., Garcia-Masso, X., Flandez, J., Behm, D.G., 2011. The progression of paraspinal muscle recruitment intensity in localized and global strength training exercises is not based on instability alone. Archives of Physical Medicine and Rehabilitation 92, 1875e1883. Critchley, D.J., Pierson, Z., Battersby, G., 2011. Effect of the Pilates mat exercises and conventional exercise programmes on transverses abdominis and obliquus internus abdominis activity: pilot randomized trial. Manual Therapy 16, 183e189. Ebenbichler, G.R., Oddsson, L.I., Kollmitzer, J., Erim, Z., 2001. Sensory-motor control of the lower back implications for rehabilitation. Medicine and Science in Sports and Exercise 33 (11), 1889e1898. Endleman, I., Critchley, D.J., 2008. Transversus abdominis and obliquus internus activity during Pilates exercises: measurement with ultrasound scanning. Archives of Physical Medicine and Rehabilitation 89, 2205e2212. Gladwell, V., Head, S., Haggar, M., Beneke, R., 2006. Does a program of the Pilates improve chronic non-specific low back pain? Journal Sport Rehabilitation 15, 338e350. Gonc ¸alves, M., Marques, N.R., Hallal, C.Z., Van Dieen, J.H., 2012. Electromyographic activity of trunk muscles during exercises with flexible and non-flexible poles. Journal of Back and Musculoskeletal Rehabilitation 24, 209e214. Granata, K., Lee, P.E., Franklin, T.C., 2005. Co-contraction recruitment and spinal load during isometric trunk flexion and extension. Clinical Biomechanics 20 (10), 1029e1037. Hermens, J.H., Freriks, B., Disselhorst-Klug, C., Rau, G., 2000. Development of recommendations for SEMG sensors and sensor placement procedures. Journal of Electromyography and Kinesiology 10, 361e374. Hodges, P.W., 2003. Core stability exercise in chronic low back pain. Orthopedic Clinics of North America 34, 245e254. Latey, P., 2002. Updating the principles of the Pilates Method: part 2. Journal of Bodywork Movement Therapies 6 (2), 94e101. Latey, P., 2001. The Pilates Method: history and philosophy. Journal of Bodywork and Movement Therapies 5 (4), 275e282.
Antagonist coactivation of trunk stabilizer muscles during Pilates exercises Loss, J.F., Melo, M.O., Rosa, C.H., Santos, A.B., La Torre, M., Silva, Y.O., 2010. Eletrical activity of external obliqu ´e and multifidus muscles during hip flexion-extension exercise performed in the Cadillac with different adjustments of springs and individual positions. Revista Brasileira de Fisioterapia 14 (6), 510e517. Marques, N.R., Morcelli, M.H., Hallal, N.R., Gonc ¸alves, M., 2012. EMG activity of trunk stabilizer muscles during Centering Principle of Pilates Method. Journal of Bodywork and Movements Therapies, Impress. Marshall, P., Murphy, B., 2003. The validity and reliability of surface EMG to assess the neuromuscular response of the abdominal muscles to rapid limb movement. Journal of Electromyography and Kinesiology 13, 477e489. McCook, D.T., Vicenzino, B., Hodges, P.W., 2009. Activity of deep abdominal muscles increases during submaximal flexion and extension efforts but antagonist co-contraction remains unchanged. Journal of Electromyography and Kinesiology 19, 754e762. Menacho, M.O., Obara, K., Conceic ¸˜ ao, J., Chitolina, M.L., Krantz, D.R., Silva, R.A., Cardoso, J.R., 2010. Electromyographic effect of mat Pilates exercise on the muscle activity of the healthy adult females. Journal of Manipulative and Physiological Therapeutics 33 (9), 672e678. Muscolino, J.E., Cipriani, S., 2004. Pilates and the powerhouse-II. Journal of Bodywork and Movement Therapies 8, 122e130. O’Sullivan, P., Dankaerts, W., Burnett, A.F., Farrel, G.T., Jefford, E., Naylor, C.S., 2006. Effect of different upright postures on spinal-pelvic curvature and trunk muscle activation in a pain free population. Spine 31 (19), E707eE712.
41
Panjabi, M.M., 1992. The stabilizing of the spine. Part I. Function, dysfunction, adaptation and enhancement. Journal of Spinal Disorders 5 (4), 383e389. Panjabi, M.M., 2003. Clinial spinal instability and low back pain. Journal of Electromyography and Kinesiology 13, 371e379. Reeves, N.P., Narendra, K.S., Cholewicki, J., 2007. Spine stability: six blind men 493 and the elephant. Clinical Biomechanics 22, 266e274. Sapsford, R.R., Hodges, P.W., Richardson, C.A., Cooper, D.H., Markewell, S.J., Jull, G.A., 2001. Co-activation of the abdominal and pelvic floor muscles during voluntary exercises. Neurology & Urodynamics 20 (1), 31e42. Souza, G.M., Baker, L.L., Powers, C.M., 2001. Eletromyographic activity of selected trunk muscles during dynamic spine stabilization exercises. Archives of Physical Medicine and Rehabilitation 82, 86e92. Urquhart, D.M., Hodges, P.W., Allen, T.J., Story, I.H., 2005. Abdominal muscle recruitment during a range of voluntary exercises. Manual Therapy 10, 144e153. Van dieen, J., Kingma, I., Van Der Gub, J.C.E., 2003a. Evidence for a role of antagonistic cocontraction in controlling trunk stiffness during lifting. Journal of Biomechanics 36, 1829e1836. Van dieen, J.H., Cholewicki, J., Radebold, A., 2003b. Trunk muscle recruitment patterns in patients with low back enhance the stability of lumbar spine. Spine 28, 834e841.
