Safety Guidelines for implementing chest stands into dance and acrobatics training Presented at the International Association of Dance & Science Medicine Montreal 2019 Sarah Reis BKin, MEd 1 Introduction What are chest stands? Chest stands are a balance involving hyperextension of the spine. Chest stands can be performed with a variety of leg positions and there are a variety of ways to enter and exit the skill. Concern for what is happening With the rise of social media dancers and non-dancers alike are being exposed to dance and flexibility content online. Children are trying stunts at home, without the supervision of qualified instructors and the proper fundamental training to execute tricks safely. There has been an increased demand for rapid flexibility gains. There is concern for the pressure social media is putting on dancers as it relates to safe practice and the prevention of injuries. We are seeing more contortion-like elements and chest stand pictures surfacing online. Some of these are executed with proper alignment and technique, supplemented by strength and control – some are not. What are the consequences of this? What risk do dancers have if they are performing chest stands before they are physically ready? Chest stands with poor technique A comprehensive list of concerns are outlined in this document. The largest technical error seen in chest stand work is “crunch- ing” in the lower back. This manifests as a sharp angle or bend in the lumbar spine. Without solid anatomical structures to pro- vide support for the lumbar spine the vertebrae in this section are greatly vulnerable. The dancer in the image above has a strong sharp angle of compression into the lumbar spine. This angle of compression puts her lower back in danger of injury. 2 Breakdown of Concerns Low back pain is highly prevalent in acrobats and multiple epidemiologic studies and reviews have documented this with prevalence ranging from 25% to 85%. Lack of supervision and a mismatch be- tween the ability of the performer and the level of skill attempted were the most commonly attributed causes. Degeneration of the Pars Interarticularis Pars Interarticularis refers to a small segment of bone that joins the facet joints in the back of the spine. Spondylolysis Spondylolysis is a crack or stress fracture that develops at the pars interarticularis, which is a small, thin portion of the vertebra that connects the upper and lower facet joints. Most commonly in dancers, this fracture occurs in the fifth vertebra of the lumbar spine, although it sometimes occurs in the fourth lumbar vertebra. Fracture can occur on one side or both sides of the bone. The pars interarticularis is the weakest portion of the vertebra. For this reason, it is the area most vulnerable to injury from the repetitive stress and overuse that is a characteristic of acrobatics. Spondylolysis can occur in people of all ages but, because their spines are still developing, children and adolescents are most suscepti- ble. Spondylolisthesis If left untreated, spondylolysis can weaken the vertebra so much that it is unable to maintain its prop- er position in the spine. This condition is called spondylolisthesis. In spondylolisthesis, the fractured pars separate and the injured vertebra slips forward on the vertebra directly below it. In children and adolescent dancers, this slippage most often occurs during periods of rapid growth—such as an ad- olescent growth spurt. During periods of growth it is very important that dance teachers use caution when working on chest stands and should supplement the training with focus on strengthening mus- cles and stabilizing joints. In addition, the training should be paired with foundational work in other styles of dance such as ballet which will develop posture, poise and understanding of alignment. Worsening of Scoliosis Scoliosis is a sideways curvature of the spine that occurs most often during the growth spurt just before puberty. There is some research that suggests contortion and gymnastic-like activities such as 3 acrobatics may increase scoliosis as a result of the athlete repetitively sitting into the defective spinal curvature in an unsupported manner. Types of Scoliosis Healthy Thoracic Lumbar Thoraco-Lumbar Combined Scoliosis Scoliosis Scoliosis Scoliosis Preservation of the Cervical Spine Cervical spine injuries often involve permanent complete or partial loss of sensory function. There are many associated complications. As is the case with all injuries of the spinal cord, injuries located higher on the spine will be more severe, with high cervical spinal cord injury often being fatal. Danc- ers who are disproportionately placing stress into their chin and neck could be compromising their cervical spine. Dislocation of the Jaw/Damage to the Teeth Dancers putting a lot of pressure into the chin during chest stand could be at risk for jaw related com- plications as well as damage to the teeth as a result of this pressure. Issues with headaches could be an indication of this developing. Weakening or Inhibition of the Abdominal Muscles Most weakness in the core is, to varying degrees, a combination of underuse; a lack of direct training; as well as inhibition due to overused/overdeveloped antagonistic opposing groups of muscles. Due to the lengthening of the abdominals that occurs while in chest stand training there is potential risk for the abdominals to be weakened over time unless properly supported with strengthening and stability training. Concern for the Skeletal Development Timeline Spinous processes and facet joints Spinous process is a bony projection off the pos- terior (back) of each vertebra. The spinous pro- cess protrudes where the laminae of the vertebral arch join and provides the point of attachment for muscles and ligaments of the spine. The facet joints are a set of synovial joints between the articular processes of two adjacent vertebrae. Without strength and control supporting the ex- tension demands in chest stand training, there is concern for the skeletal development of the spinous processes and facet joints. 4 Screening Assessment for the readiness to begin chest stand training Review of muscle length, hip flexor length via a modified Thomasest T The dancer lays on their back on an examination table or modified stack of mats in acrobatics class and holds the uninvolved knee to his or her chest. The dancer should allow the involved extremity to lie flat, working to hold the knee to the chest as it flattens out the lumbar lordosis and stabilizes the pelvis. If the iliopsoas muscle is shortened, or a contracture is present, the lower extremity on the involved side will be unable to fully extend at the hip. This constitutes a positive Thomas test. Sometimes, with a very flexible patient, the Thomas test will be normal despite a iliopsoas dysfunction being present, which could be a concern for the dancer population. However, a posi- tive test is a good indicator of iliopsoas hypertonicity. The chart below provides indication of what to look at when you com- plete this screening. With this information you can better target stretching specific muscles to prepare for chest stand work. The psoas is very important for chest stand training because it con- nects to the five lumbar vertebrae. Other signs from the Thomas test: Symptom Potential Concern Opposite hip flexes without knee extension Tight Iliopsoas Hip abducts during test Tight Tensor Fascaie Latae Knee extension occurs Tight Rectus Femoris Lateral rotation of the tibia Tight Biceps Femoris 5 Review Relationship of Athletes Hip Flexors and Gluteals Hip flexors and gluteals, both are often weak but for different reasons. Often to correct one a dancer needs to also correct the other. Hip flexors are typically tight in the vast majority of dancers, which may be a result of sitting in desks at school all day. Tight hip flexors lead to inhibition of their function and strength, which will not effectively be corrected through direct training but rather through stretch- ing and fascial release. Gluteals can be weak for many reasons but often it may simply be lack of use in day-to-day life and training. Gluteals need direct strength training but they may be equally inhibited due to the antagonistic tight hip flexors. The ability to train the gluteals effectively often requires the release of the hip flexors, and the key to the prevention of tight hip flexors is having strong glutes. In assessing the dancer for readiness for chest stand work, review the hip flexors and firing of glutes. The glutes will be important in stabilizing the chest stand when the dancer is working to get their feet together and the body lifted out of the lower back, at the same time the hip flexors will be extending. T-Spine Extension and Posture If Kyphosis is present in the dancer, there is concern for more extension in the lower back. Kypho- sis is a spinal disorder in which an excessive outward curve of the spine results in an abnormal rounding of the upper back. It can occur at any age, but is common during adolescence. Stability in an Arched Position Can the dancer demonstrate stability in an arched position? If the dancer is in a chest stand do they wobble consistently in any direction? Do they have refined control in the ability to show good articulation of the spine in bridge to wall touch extension? Straight and Controlled Can the dancer demonstrate a straight and controlled chest stand before anything else? This demon- strates they are working to master the control required to execute chest stands safely. Dancers who are unable to demonstrate a straight chest stand are likely to “flop” into compromised positions and/or are lacking strength. Abdominal Strength Test In addition to the strength assessment featured later in this document, can the dancer show effec- tive use of the ab rolling exercise? Using plank to assess strength only activates the muscles in an isometric (isotonic) position, which means the muscles remain the same length.