Hip and ankle range of motion and hip muscle strength in young female ballet dancers and controls

Serial night casting increases ankle dorsiflexion range in children and young adults with Charcot-Marie-Tooth disease: a randomised trial

QUESTION

Does 4 weeks of serial night casting followed by 4 weeks of stretching of the gastrocnemius and soleus improve ankle dorsiflexion range and other outcomes compared with no intervention in children and young adults with Charcot-Marie-Tooth disease?

DESIGN

Randomised trial with concealed allocation, assessor blinding, and intention-to-treat analysis.

PARTICIPANTS

30 children and young adults with Charcot-Marie-Tooth disease and restricted ankle dorsiflexion range.

INTERVENTION

The experimental group received 4 weeks of serial night casting followed by 4 weeks of weightbearing stretches. The control group received no intervention.

OUTCOME MEASURES

Primary outcome was ankle dorsiflexion range; secondary outcomes included foot deformity, mobility, balance, falls, and self-reported activity limitations. Outcomes were measured at baseline, 4, and 8 weeks.

RESULTS

By 4 weeks, serial night casting had increased ankle dorsiflexion range by a mean of 4 deg (95% CI 2 to 6) more in the experimental group than the control group. After a further 4 weeks of weightbearing stretches, the experimental group still had a mean of 3 deg (95% CI 0 to 5) more ankle dorsiflexion range than the control group. Other than reduced time to walk 10 metres at self-selected pace favouring night casting at 4 weeks, outcomes did not differ between groups at any time point. Two minor adverse events were reported in the experimental group.

CONCLUSION

4 weeks of serial night casting increased ankle dorsiflexion range compared with no intervention, but at 8 weeks there was no significant difference between groups.

Factors associated with foot and ankle strength in healthy preschool-age children and age-matched cases of Charcot-Marie-Tooth disease type 1A

Charcot-Marie-Tooth disease affects foot and ankle strength from the earliest stages of the disease; however, little is known about factors influencing normal strength development or the pathogenesis of foot weakness and deformity in Charcot-Marie-Tooth disease. The authors investigated factors associated with foot and ankle strength in healthy preschool-age children and compared to age-matched cases of Charcot-Marie-Tooth disease type 1A. In healthy children, ankle dorsiflexion range of motion was one of the strongest independent correlates of foot and ankle strength. Compared with healthy children, those with Charcot-Marie-Tooth disease type 1A had significantly less dorsiflexion strength and range as well as imbalance in inversion-to-eversion and plantarflexion-to-dorsiflexion strength ratios. Given the association between ankle dorsiflexion strength and range in the healthy children, and the abnormality of these parameters in Charcot-Marie-Tooth disease, investigation of the cause-effect relationship is warranted to identify more targeted therapy and further understand the pathogenesis of foot deformity in Charcot-Marie-Tooth disease.

Evolution of foot and ankle manifestations in children with CMT1A

We studied the timing and progression of foot and ankle changes in 81 children with genetically confirmed Charcot-Marie-Tooth disease type 1A (CMT1A) and determined their impact on motor function and walking ability. Foot deformity, weakness, pain, cramps, and instability were a common feature of CMT1A. Foot structure evolved toward pes cavus from early childhood to adolescence, although a subgroup with normal and planus feet remained. Foot strength increased with age, although compared to age-equivalent norms it declined from 4 years. Factors associated with evolving foot deformity included muscle weakness/imbalance, restricted ankle flexibility, and joint hypermobility. Regression modeling identified dorsiflexion weakness, global foot weakness, and difficulty toe-walking as independent predictors of motor dysfunction, while pes cavus and difficulty heel-walking were predictors of poor walking ability. Foot problems are present from the earliest stages of the disease and can have a negative impact on function. Early foot and ankle intervention may prevent long-term disability and morbidity in CMT1A.

Pressure characteristics in painful pes cavus feet resulting from Charcot-Marie-Tooth disease

Charcot-Marie-Tooth (CMT) disease often presents with peripheral muscle imbalance associated with a painful cavus (medial high-arched) foot deformity which becomes increasingly severe and rigid as the disease progresses. The purpose of this study was to investigate the effect of pes cavus on foot pain and dynamic plantar pressure in CMT, and to explore the relationships between plantar pressure and pain. Sixteen participants diagnosed with CMT and painful pes cavus were assessed for foot posture, ankle dorsiflexion range of motion, levels of foot pain, functional impairment, health-related quality of life and plantar pressure distribution while walking. Plantar pressure parameters (mean pressure, peak pressure, pressure-time integral) and contact duration were measured using the Novel Pedar in-shoe capacitance transducer system and the foot was divided into rearfoot, midfoot and forefoot regions for analysis. Increasing cavus foot deformity was associated with more widespread foot pain and increased pressure under the forefoot and midfoot regions. In contrast, peak pressure decreased under the rearfoot. Neither relationship was found between foot pain intensity and any of the pressure variables, nor was ankle dorsiflexion range of motion correlated with pain location, intensity or degree of pes cavus. Although pes cavus in CMT is associated with substantial pain and dysfunction, there is no clear link between foot pain and plantar pressure. The more severe the degree of pes cavus, however, the more pressure develops under the lateral margin of the foot; probably as a result of the changed foot-ground contact seen during gait.

Dance training intensity at 11-14 years is associated with femoral torsion in classical ballet dancers

OBJECTIVE

To examine in a cross sectional study the influence of femoral torsion (FT) and passive hip external rotation (PER) on turnout (TO). Starting age, years of classical ballet training, and current and past dance training intensity were assessed to determine their influence on FT, PER, and TO in pre-professional female dancers.

METHODS

Sixty four dancers (mean (SD) age 18.16 (1.80) years) were recruited from four different dance training programmes. They completed a dance history questionnaire. FT was measured using a clinical method. PER was measured with the subjects prone, and TO was measured with the subjects standing.

RESULTS

Mean TO was 136 degrees, mean unilateral PER was 49.4 degrees, and mean FT was 18.4 degrees. A positive correlation was observed between PER combined (PERC) and TO (r = 0.443, p < 0.001). A negative association was found between FT combined (FTC) and PERC (r = -0.402, p = 0.001). No association was found between starting age or years of classical ballet training and FTC, PERC, or TO. Dancers who trained for six hours a week or more during the 11-14 year age range had less FT than those who trained less (mean difference 6 degrees, 95% confidence interval 1.4 to 10.3). Students currently training for longer had higher levels of TO (p < 0.001) but comparable PERC and FTC.

CONCLUSION

FT is significantly associated with PERC. Dancers who trained for six hours a week or more at 11-14 years of age had significantly less FT. FTC had a significant influence on PERC, but no influence on the execution of TO.

Range of joint movement in female dancers and nondancers aged 8 to 16 years: anatomical and clinical implications

BACKGROUND

Little data are available on changes that occur with age in joint range of motion in dancers and nondancers.

HYPOTHESIS

In dancers, joint range of motion will increase with age, whereas it will decrease in nondancers, independent of the joint studied.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

The study population included 1320 female dancers, aged 8 to 16 years, who participated in different types of dancing classes (classical ballet, modern dance, jazz, etc) and 226 nondancers of similar age. Range of motion was measured for the hip, knee, ankle, foot, and spinal joints.

RESULTS

The pattern of differences in range of motion with age varied in different joints and types of movement. (1) For combined ankle and foot plantar flexion (pointe), ankle plantar flexion, and hip external rotation, there was no change in range of motion in dancers, whereas range of motion diminished with age in the nondancers. (2) For ankle dorsiflexion, neither group showed any change with age, and range of motion was significantly greater in the nondancer group. (3) For knee flexion, hip flexion, and hip internal rotation, range of motion decreased with age in both groups. (4) For hip abduction, range of motion decreased with age in dancers and remained constant in the nondancers. (5) For hip extension, range of motion increased in both groups. (6) For lower back and hamstrings, range of motion increased among dancers with age and remained constant among nondancers.

CONCLUSION

Dancers and teachers should realize that passive joint range of motion is unlikely to improve with age. Therefore, the major goal of a dancing program should focus on exercises that retain the natural flexibility of the dancers' joints rather than trying to improve them.

Dancing for bone health: a 3-year longitudinal study of bone mineral accrual across puberty in female non-elite dancers and controls

INTRODUCTION

Weight-bearing exercise during growth enhances peak bone mass. However, the window of opportunity for optimizing positive effects of exercise on peak bone mass remains to be fully defined. Ballet dancing provides a model of mechanical loading patterns required to site-specifically modulate bone.

METHODS

We assessed the effects of ballet dancing on bone mineral accrual in female non-elite dancers and normally active controls for 3 years across puberty. We recruited 82 ballet dancers and 61 controls age 8-11 years at baseline. Participants were measured over 3 consecutive years; however, the overlap in ages allowed analysis of the groups across 8-14 years of age. We annually assessed bone mineral content (BMC) at the total body (TB), including upper and lower limb regions, and biannually assessed BMC at the proximal femur and lumbar spine (LS) using dual x-ray absorptiometry (DXA). We derived TB lean mass and fat mass from DXA TB scans. Anthropometry, exercise levels, and calcium intake were also measured biannually. Maturational age was determined by age at peak height velocity (PHV). A multilevel regression model was used to determine the independent effects of body size, body composition, maturation, exercise levels, and calcium intake at each measurement occasion.

RESULTS

When adjusted for growth and maturation, dancers had significantly greater BMC at the TB, lower limbs, femoral neck (FN), and LS than controls. Excepting the FN region, these differences became apparent at 1 year post-PHV, or the peripubertal years, and by 2 years post-PHV the differences represented a cumulative advantage in dancers of 0.6-1.3% (p<0.05) greater BMC than controls. At the FN, dancers had 4% (p<0.05) greater BMC than controls in prepuberty and maintained this advantage throughout the pubertal years.

CONCLUSIONS

Results from this novel population provide evidence for modest site-specific and maturity-specific effects of mechanical loading on bone.

Associations between turnout and lower extremity injuries in classical ballet dancers

STUDY DESIGN

Descriptive correlational study.

OBJECTIVES

To determine relationships between aspects of turnout and injury history in preprofessional classical ballet dancers, and to determine the clinical utility of various methods used to assess turnout.

BACKGROUND

In Australia 50% of professional dancers currently have persistent or recurrent injuries, with 36% of these injuries commencing before 18 years of age (preprofessional level). Overuse or nontraumatic dance injuries are often attributed to faults in technique, with poor turnout and inappropriate compensatory strategies consistently cited as the main cause.

METHODS AND MEASURES

Twenty-nine dancers (24 female), aged 15 to 22 years, were recruited from a preprofessional classical ballet program. Measurements were taken of passive and active hip external rotation (ER) range of motion (ROM) in supine, and functional turnout angles in standing. Three turnout variables were derived: active ER lag, compensated turnout, and static-dynamic turnout difference. Injury history over the previous 2 years was ascertained by interview. Pearson product moment and Spearman rank correlation coefficients were used to determine associations between turnout variables and injury history.

RESULTS

All dancers reported a history of injury, with 93.1% reporting a history of nontraumatic injuries and 41.4% reporting a history of traumatic injuries. Number and severity of nontraumatic injuries were associated with reduced functional turnout (r or rho>0.38; P<.04), but not with hip ER ROM. Number and severity of traumatic injuries were not associated with turnout. No correlation was found between hip ER ROM and functional turnout.

CONCLUSIONS

Functional measures of turnout are more relevant than hip ER ROM to prevalence of nontraumatic dance injuries. Control of turnout in classical ballet dancers should be assessed dynamically and in functional positions.

Effect of dry needling of gluteal muscles on straight leg raise: a randomised, placebo controlled, double blind trial

OBJECTIVES

To use a randomised, double blind, placebo controlled trial to establish the effect on straight leg raise, hip internal rotation, and muscle pain of dry needling treatment to the gluteal muscles in athletes with posterior thigh pain referred from gluteal trigger points.

METHODS

A randomised, double blind, placebo controlled trial of 59 male runners was performed during the 2002 Australian Rules football season. Subjects were thoroughly screened and had magnetic resonance imaging of their hamstring muscles to exclude local pathology. The inclusion criterion was reproduction of recognisable posterior thigh pain with the application of digital pressure to the gluteal trigger points. Subjects randomly received either therapeutic or placebo needle treatment on one occasion at their gluteal trigger points. Range of motion and visual analogue scale data were collected immediately before, immediately after, 24 hours after, and 72 hours after the intervention. Range of motion was measured with passive straight leg raise and hip internal rotation. Visual analogue scales were completed for hamstring and gluteal pain and tightness at rest and during a running task.

RESULTS

Magnetic resonance imaging scans revealed normal hamstring musculature in most subjects. Straight leg raise and hip internal rotation remained unchanged in both groups at all times. Visual analogue scale assessment of hamstring pain and tightness and gluteal tightness after running showed improvements immediately after the intervention in both groups (p = 0.001), which were maintained at 24 and 72 hours. The magnitude of this improvement was the same for therapeutic and placebo interventions. Resting muscle pain and tightness were unaffected.

CONCLUSIONS

Neither dry needling nor placebo needling of the gluteal muscles resulted in any change in straight leg raise or hip internal rotation. Both interventions resulted in subjective improvement in activity related muscle pain and tightness. Despite being commonly used clinical tests in this situation, straight leg raise and hip internal rotation are not likely to help the therapist assess response to treatment. Patient reports of response to such treatment are better indicators of its success. The mechanisms by which these responses occur and the reasons for the success of the placebo needling treatment are areas for further investigation.

An evaluation of differences in hip external rotation strength and range of motion between female dancers and non-dancers

OBJECTIVES

To evaluate the differences in hip external rotation (ER) strength and inner, outer, and total hip ER range of motion (ROM) between dancers and non-dancers and between left and right sides in each group.

METHODS

Seventy one subjects (34 dancers and 37 non-dancers) volunteered for this study. The strength (truncated range average torque (TRAT), work, and angle specific torque (AST)) of the hip external rotator muscle group, through the full available active hip ER ROM, was evaluated using concentric isokinetic (30 degrees /s) testing on a KinCom dynamometer. Adjustment for lean body mass (LBM) was made for comparison of strength between groups. A two way repeated analysis of covariance was used to compare strength between groups. A two way repeated analysis of variance was used to compare strength between sides and ROM between groups and sides. Bonferroni correction was made for multiple analyses, and significance was accepted at p<or=0.05.

RESULTS

AST at 0 degrees , 20 degrees , 30 degrees , and 40 degrees of hip ER was greater in the dancers than the non-dancers (p<or=0.022). TRAT, work, AST(0 degrees ), AST(20 degrees ), and AST(30 degrees ) of hip ER were all greater on the right side than the left (p = 0.007) in both groups. Dancers had greater inner ER ROM (p = 0.013) and less outer ER ROM than non-dancers (p<or=0.001). There was no difference in total ER ROM between groups (p = 0.133). The right side had greater inner ER (p<or=0.001) and total ER ROM (p<or=0.001) than the left in both groups.

CONCLUSIONS

Ballet dancers have greater inner range, angle specific strength and inner range ER ROM, demonstrated by a shift in the dancers' strength curves. This shift in the strength curve towards the inner range of hip ER may be an adaptive training response.

The Dancer as a Performing Athlete

The physical demands placed on dancers from current choreography and performance schedules make their physiology and fitness just as important as skill development. However, even at the height of their professional careers, dancers' aerobic power, muscular strength, muscular balance, bone and joint integrity are the 'Achilles heels' of the dance-only selection and training system. This partly reflects the unfounded view, shared by sections of the dance world, that any exercise training that is not directly related to dance would diminish dancers' aesthetic appearances. Given that performing dance itself elicits only limited stimuli for positive fitness adaptations, it is not surprising that professional dancers often demonstrate values similar to those obtained from healthy sedentary individuals of comparable age in key fitness-related parameters. In contrast, recent data on male and female dancers revealed that supplementary exercise training can lead to improvements of such fitness parameters and reduce incidents of dance injuries, without interfering with key artistic and aesthetic requirements. It seems, however, that strict selection and training regimens have succeeded in transforming dance to an activity practised by individuals who have selectively developed different flexibility characteristics compared with athletes. Bodyweight targets are normally met by low energy intakes, with female dance students and professional ballerinas reported to consume below 70% and 80% of the recommended daily allowance of energy intake, respectively, while the female athlete 'triad' of disordered eating, amenorrhoea and osteoporosis is now well recognised and is seen just as commonly in dancers. An awareness of these factors will assist dancers and their teachers to improve training techniques, to employ effective injury prevention strategies and to determine better physical conditioning. However, any change in the traditional training regimes must be approached cautiously to ensure that the aesthetic content of the dance is not affected by new training techniques. Since physiological aspects of performing dance have been viewed primarily in the context of ballet, further scientific research on all forms of dance is required.

Medical and rehabilitation issues in classical ballet

Classical ballet is a demanding professional occupation, with participants who are often underserved in terms of accurate diagnosis and appropriate comprehensive medical care. The view that follows is designed to be as global and insightful as published to date. Specific rehabilitation considerations, dance mechanics, idiosyncratic differential diagnosis, and personality and equipment issues are discussed, and a rational view of dogma is presented.

Changes in hip and ankle range of motion and hip muscle strength in 8-11 year old novice female ballet dancers and controls: a 12 month follow up study

OBJECTIVES

To evaluate in a 12 month longitudinal study changes in hip and ankle range of motion and hip muscle strength in young female novice ballet dancers.

METHODS

Fifty three of the original 77 (69%) female dancers aged 8-11 years and 40 of the original 49 (82%) controls returned for follow up measurements one year later. Supine right active hip external (ER) and internal (IR) rotation were measured using an inclinometer. A turnout protractor was used to assess standing active turnout range. Range of right weight bearing ankle dorsiflexion and calf muscle length were measured in a standing lunge position using an inclinometer. A manual muscle tester was used to assess right hip flexor, IR, ER, abductor and adductor strength.

RESULTS

The mean (SD) 12 month change in hip ER did not differ between dancers (11.7 (11.3)degrees) and controls (8.1 (17.6)degrees). Dancers gained 12.5 (13.5)degrees hip IR which was significantly greater than controls (0.5 (13.9)degrees). Greater IR change was associated with improved IR strength (r = 0.34, p<0.001). Dancers increased total turnout (12.0 (16.7)degrees) significantly more than controls (2.2 (20.0)degrees). There was no significant change in ankle dorsiflexion range in either group. Dancers and controls increased in all measures of hip muscle strength (p<0.001) and dancers achieved significantly greater gains in three out of five muscle groups (all, p<0.05).

CONCLUSIONS

Total hip range of motion increased in both ballet students and controls at this young age. However, ankle dorsiflexion did not, which is probably due to this movement being blocked by bony apposition, rather than soft tissue stretch. This has implications for ballet teachers, as it has long been accepted that this movement could be improved with training. Dancers had greater increases in hip strength after 12 months compared with controls in muscles specific for ballet, suggesting that hip strength can be trained at this young age. Whether these gains are permanent requires further study.