Examples of Beighton test measures. a Positive Beighton forward bend. b Positive Beighton thumb to forearm. Photographs courtesy of James Koepfler
Hypermobile dancers must be educated on the need to increase strength and work on stability to reduce shearing forces at their joints. The hypermobile dancer will frequently complain of feeling “stiff.” Their muscles may be tighter as they are working harder than the average individual just to stand and maintain postural stability at joints lacking adequate passive restraint of the ligaments. Screening for hypermobility offers the opportunity to assure that the dancer will be referred to a physical therapist who will teach her or him how safely to release stiffness in the muscles, rather than pushing into extreme ranges of motion where they are more likely to be overstretching already loose and compromised joint ligaments and capsules. Attention to promoting stability around the joints is paramount in helping the hypermobile dancer to avoid injury.
There are many characteristics of a hypermobile dancer that can affect multiple potential causes of injury. For example, due to altered joint proprioception hypermobile dancers may struggle at times to keep tempo with music. With a greater demand on their muscles to compensate for the lack of adequate ligament or capsular stability, they are working harder than their non-hypermobile peers, even during what might seem to be simple gestures and movements. This results in earlier onset of fatigue. With the known link between fatigue and injury for all dancers , it is not surprising that there is an even greater incidence of injury in the hypermobile dancer [16, 22].
Screening tests for cardiovascular fitness vary regarding parameters assessed and how the information can be applied. Research in this area has helped provide a better understanding of the physiological demands of dancing. In general, dance is categorized as a high intensity, intermittent form of exercise . Cardiovascular testing in performance has shown that both the aerobic and anaerobic energy systems may be utilized, while dance class seems to stimulate only the anaerobic system, producing energy bursts for 10–12 s . If class has lesser cardiovascular demands than performance, then a dancer’s aerobic fitness may not be adequate for the demands of repetitive rehearsals or performance, leading to fatigue and injury. Screening tests looking at cardiovascular health, fitness, and recovery can be very helpful in establishing a baseline and helping to motivate young dancers to perform supplemental cardiovascular training.
The accelerated 3-min step test is utilized by many professional companies as a measure of cardiovascular fitness, as it is simple and quick to implement (Fig. 3.2). In addition to other parameters, physical fitness is characterized by the post-exercise heart rate, considered to be an indicator of cardiorespiratory fitness. Bronner and Rakov have compared an accelerated 3-min step test (112 beats min) to the well-studied YMCA step test (96 beats min) and a benchmark standard, the incremental treadmill test, using heart rate (HR) and oxygen consumption (VO2) as variables . They have repeatedly found the accelerated 3-min step test to be an efficient, acceptable tool for testing cardiac recovery in dance populations when compared to other gold standards. In younger dancers the 3-min Kasch Pulse Recovery Test (KPR Test) could be indicated, as it delineates differences between children 6–9 and 10–12 years old . The standard YMCA 3-min step test may be indicated for recreational dancers, while for pre-professional adolescents utilizing the 112 beat accelerated step test may be most appropriate.
3-min step test—forward step up. Photograph courtesy of James Koepfler
There are many other screening tests that examine cardiovascular fitness that are useful for dance, such as the dance-specific aerobic fitness test (DAFT), that can also be implemented if the time and resources required to utilize them are available .
Range of Motion/Flexibility
Dancers generally work at the extremes of joint motion; many studies demonstrate greater range of motion than what is observed in the general population [28, 29]. When assessing range of motion in young dancers it can be helpful to screen for passive range of motion as it pertains to flexibility. In a still-growing population this can be very informative in helping a young dancer understand some of the limitations in motion that tight muscles can cause. As bone tends to grow faster than muscle, often a growing dancer will experience issues with flexibility along with strength of major muscle groups. Changes also occur in proprioception and biomechanics, impacting performance and increasing risk for injury. In general, injury reported during growth spurts may be due to a period of “relearning” when previously learned technique no longer relates to the new body structure. Many screens tend to observe technique only in evaluating some of these issues, but screening for passive range of motion can help establish whether the dancer possesses enough flexibility to achieve proper technique. Some screens will actually measure range with a goniometer to track changes, but full measurements constitute an evaluation, not a screening. A screening that includes flexibility should only have yes or no answers when establishing whether there is enough flexibility present. Generally, when range of motion tests are performed to establish flexibility they are done passively and stopped at the “first end feel,” defined as the first onset of resistance or compensatory adjacent joint movement.
Hip motion and its effect on the spine and lower extremities is imperative to proper technique, especially in ballet. Screening for tightness in the iliopsoas with a Thomas test will generally show that most dancers are tight in the deep hip flexors, which can make it difficult to correct an anterior pelvic tilt, increase lumbar lordosis, place lower abdominals in an efficient position, and affect height of the arabesque. The Ely test for the quadriceps and Ober tests for the iliotibial band are also often positive and tight, especially in growing male dancers. Passive straight leg raise (SLR) helps establish the length of the hamstrings. In technique, if a young dancer is expected to flex the hip forward with knee extension higher than 90º, to accomplish this he or she needs at least 90º passive range of motion in order to maintain proper pelvic alignment. At the professional level a passive SLR of greater than 120º is expected. Clinically, tightness in the hamstring muscles can contribute to anterior hip pain and pathology, as the hip flexors overwork to achieve a leg height that is not possible with restrictions in hamstring flexibility.
Screening passive range of motion for external and internal rotation can be very helpful in ballet students, in particular when the hip is in extension, to establish baseline motion. Screening for motion in this area can indicate whether a dancer is using all the motion that is available. Evaluating internal rotation can also be very helpful to either establish that the motion is excessive in dancers who may have femoral anteversion, or very limited, as many professional level dancers present with 10º or less of internal rotation. This also provides the opportunity to educate the adolescent dancer on the importance of incorporating internal rotation stretches and strengthening exercises to balance rotation around the hip joint. Lack of internal rotation can lead to various injuries in the lower back, SI joint, and hips. Also, screening for significant asymmetries in hip rotation is important, as many dancers will present with differences between hips. With external rotation, to reduce the risk of injury dancers should work to equalize the lesser side. If the dancer consistently forces the lesser turned out hip to match the one with more turnout, problems may result around the hip joint of the lesser one and possibly also further up or down the kinetic chain in the lower back, knee, or ankle and foot.
Screening for tightness in the lower leg at the ankle and foot is also extremely important to assess for areas that demonstrate imbalance or lack of sufficient motion for proper technique. The most common injuries in dance are often at the ankle, due to limitations in dorsiflexion or plantar flexion. Studies have shown that dorsiflexion range decreases with increasing dance experience and ability, while plantar flexion is observed to increase with enhanced dance proficiency . Adequate ankle dorsiflexion is important to achieve proper demi-plié (hip and knee flexion with ankle dorsiflexion) as it provides shock absorption in both preparation for and recovery from jumps and turns .
Screening to determine whether a dancer has enough plantar flexion to achieve proper alignment can be one significant factor in assessing the safety of pointe work. The motion required to achieve that technique is greater than the normative data reported in the general population [32, 33]. To attain the correct position en pointe requires more than 90º of combined motion in the talocrural, subtalar, and midtarsal joints. Proper alignment is demonstrated when the line of the metatarsals (top surface of the forefoot) is parallel to the line of the tibia (front of the shin) when the foot is pointed. During a screen, asymmetry en pointe and/or in demi-pointe in parallel can indicate differences in strength as well as range of motion that may need to be addressed with further evaluation.
Screening for ROM at the 1st metatarsal phalangeal (MTP) joint can be very important to see whether there are deficits in motion that will cause issues when weight bearing in demi-pointe (Fig. 3.3a–c). The demi-pointe position is the movement between the extremes of plié (end-range dorsiflexion) and pointe (end-range plantar flexion), where the foot is less stable. It is used in static balance poses for dancers, is the position that male dancers generally use for turning, and requires 90º of dorsiflexion in the 1st MTP joint. The demi-pointe position also forms the transitional phase when taking off and landing from jumps. In demi-pointe all the toes should be relaxed. If clawed toes or gripping of the toes is observed, it is often a sign of weakness in the deep intrinsic foot muscles. Decreased range of motion into dorsiflexion of this joint, along with foot type, can lead to alignment issues, as the dancer can not be fully over the 1st and 2nd rays due to lack of motion, and generally compensates with inversion (sickling) or winging (eversion) of the foot, increasing the risk of injury.
Assessing 1st metatarsal phalangeal (MTP) joint motion. a 1st MTP joint extension accurately measured with ankle in plantar flexion. b Restricted 1st MTP extension with ankle dorsiflexed and first ray fixed, suggesting limited excursion of the flexor hallicus longus (FHL) muscle. c Approximately 20 degrees of MTP extension indicating normal excursion of the FHL as in Fig. 3.3b
In all sports, poor core stability has been identified as a risk factor for both upper and lower extremity injury, along with inadequate neuromuscular control. Assessing core strength and pelvic stability both with muscle testing and functional testing is probably the most important aspect of any screening process, and should be the first priority. Adolescent dancers commonly use their global stabilizers to maintain stability of the trunk, underutilizing the local core spinal stabilizers. This encourages imbalanced use of iliopsoas and thigh musculature, which may lead to multiple issues in the lower back and hip. Proximal control of the hip and trunk is an important indicator of lower extremity stability, as a dancer needs to be able to control his or her center of gravity over a small base of support. Screening should focus on strength and recruitment of the transversus abdominis and lower abdominal area, as most young dancers are surprisingly weak there. Weakness can be exacerbated by standing in a lordotic posture (sway back) with tight deep hip flexors and an anterior pelvic tilt compromising the mechanical efficiency of the lower abdominals and efficient recruitment of the transversus abdominis, along with the pelvic floor and multifidi in the spine, which can affect alignment of the entire spine. The gold standard for testing lower abdominal strength is the Kendall and Kendall double-leg-lowering test, but its reliability of grading has been called into question . It is imperative that this test not only be done correctly, but also that young dancers and dance teachers know it is a test and never to be used as an exercise.
Screening for strength at the hip can be instrumental in identifying areas that if weak can contribute to injury. Athletes with weak hip abductors and hip external rotator muscles have been shown to be likely to sustain an ankle injury during a sports season . Weakness in the hip abductors and adductors can be screened with functional testing such as the step down test or Trendelenburg test. When screening certain muscle groups, strength in the end range, with the muscle at its shortest length, can be significant, as that is where the muscle will be most utilized. For example, the external rotators of the hip need to be very strong at their end range, which is not typical for the strength–tension relationship of muscle. Testing hip external rotation strength provides an opportunity to compare active turnout to passive range. In addition, many lower extremity injuries have been shown to be related to lack of external rotator strength, in particular patellofemoral pain syndromes [36, 37].
The ability to control balance during activity is critical for preventing lower extremity injury. Screening for postural control and the ability to balance can be very helpful in discovering areas of weakness, lack of range of motion, and decreased proprioception. Testing can also help the practitioner detect residual deficits that remain following a previous injury. With training, dancers learn to adjust postural responses (achieve and maintain balance) to different conditions. The systems involved in balance include the visual system, the vestibular system located in the inner ear, and the somatosensory system, which includes touch, nociception (which senses pain or harm), and proprioception. Screening to evaluate balance can involve decreasing the input of one of these systems, such as vision, in the single leg stance with eyes closed. The age of the dancers being evaluated may help determine the type of testing utilized, as children 12 years and under rely predominantly on vision for balance, while the other systems mentioned above are added with increasing maturity . In pre-professional adolescents and the professional dancer, a single leg balance test with eyes closed for 60 s is the gold standard. Screening with a movement-based test, such as the Star Excursion Test, may be more beneficial in younger dancers, or when dynamic balance is being tested. It should also be recognized that growth spurts often affect motor development, as changes occurring in body mass, limb length, proportions, flexibility, and strength will cause variability in balance and coordination.