An observational study in Musculoskeletal Health, Lower Extremity Biomechanics and Foot Health, sponsored by University hospital of Odense. Not yet recruiting. Open to participants aged 7 Years to 16 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-12.
Sponsored by University hospital of Odense · Observational
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This study aims to investigate lower limb and foot health in children aged 7-16 years who participate in ballet or football. Both sports provide important health benefits but involve repetitive movements and physical demands that may affect the developing musculoskeletal system.
The study will include approximately 148 children: 74 ballet dancers from the Royal Danish Ballet School and 74 football players from participating Danish football clubs. Their findings will be compared with existing reference data from 501 typically developing Danish schoolchildren.
The main objective is to determine whether children participating in ballet have greater outward hip rotation than children in the reference group. The researchers will also examine ankle mobility, foot shape, joint flexibility, muscle function, balance, pain, and quality of life. Differences between ballet dancers and football players will be explored.
Each child will undergo a standardized clinical examination, including measurements of joint movement, lower limb alignment, and foot characteristics. Additional assessments will include three-dimensional foot scanning, functional movement tests, and questionnaires about pain, physical activity, and quality of life.
A subgroup of children will also participate in observations and group interviews to explore how young athletes experience and manage pain and soreness during training.
This is an observational study. No experimental treatment or intervention will be provided. The findings may improve our understanding of normal physical development and sport-related adaptations in active children and help inform future approaches to preventing musculoskeletal problems in young athletes.
Background and Rationale
Participation in organized sports during childhood is associated with substantial physical, psychological, and social benefits. However, intensive training during skeletal growth may also be associated with adaptations in joint mobility, lower limb alignment, and foot morphology, as well as musculoskeletal pain and overuse-related conditions.
Ballet and football impose different mechanical demands on the developing musculoskeletal system. Ballet requires substantial hip external rotation, ankle plantarflexion, and specific postural control, whereas football involves repetitive running, kicking, jumping, and rapid changes of direction.
Despite these differences, comprehensive data on lower limb anthropometrics, rotational profiles, foot morphology, functional characteristics, and pain in young athletes remain limited.
A previous Danish study established reference data on lower limb and foot characteristics in 501 typically developing schoolchildren aged 6-17 years. The present study will extend this research by examining children participating in ballet and football.
Study Objectives
The primary objective is to compare passive external hip rotation between ballet dancers and an age- and sex-frequency-matched reference cohort of typically developing children.
The primary hypothesis is that ballet dancers demonstrate greater passive external hip rotation than children in the reference cohort.
Secondary objectives include:
Comparisons involving football players and sport-specific functional assessments will be considered exploratory.
Study Design and Participants
This is an observational, cross-sectional study involving approximately 148 children aged 7-16 years, including 74 ballet dancers and 74 football players.
Participants will be recruited from the Royal Danish Ballet School and selected Danish football clubs. Eligible children will belong to predefined age groups (7-8, 11-12, or 15-16 years) and meet age- and sport-specific minimum training requirements.
Clinical findings will be compared with an existing reference cohort of 501 typically developing Danish schoolchildren. Comparisons with the reference cohort will account for age group and sex.
Clinical and Functional Assessments
Each participant will undergo a standardized clinical examination, including:
Sport-specific functional assessments will examine movement characteristics, joint mobility, balance, and neuromuscular control. These assessments will include evaluation of active turnout in ballet dancers and functional movement tasks relevant to the participants' sports.
Three-dimensional foot scanning will be performed using a Volumental scanner to obtain standardized measurements of foot morphology, including foot length, width, arch height, instep dimensions, and other anatomical parameters.
Footwear dimensions and fit will also be assessed.
Patient-reported outcome measures will evaluate musculoskeletal pain, ankle and foot function, health-related quality of life, and sport-related overuse problems. Instruments will include age-appropriate pain rating scales, the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C), the Pediatric Quality of Life Inventory (PedsQL), and the Oslo Sports Trauma Research Centre (OSTRC) questionnaire.
Qualitative Component
A complementary qualitative component will explore children's experiences of lower limb pain, soreness, and training culture.
Short-term observations will be conducted during regular ballet and football training sessions over approximately 3-4 weeks.
Subsequent focus group interviews will involve selected children and their teachers or coaches. Interviews will examine experiences of pain, communication about symptoms, and attitudes toward physical discomfort during training.
Qualitative data will be evaluated using reflexive thematic analysis.
Statistical Analysis
The primary analysis will compare passive external hip rotation between ballet dancers and the reference cohort using linear regression.
The participant-level mean of the right and left hip measurements will be used as the primary outcome. Results will be presented as mean differences with 95% confidence intervals.
Secondary analyses will evaluate associations between anthropometric measurements, range of motion, functional characteristics, pain intensity, and patient-reported outcomes.
Multivariable regression models will account for relevant potential confounders, including age, sex, body mass index, and training volume, where applicable.
Generalized estimating equations will be used when bilateral measurements are analyzed separately to account for within-participant correlation.
Multiple secondary and exploratory comparisons will be addressed using the Benjamini-Hochberg false discovery rate procedure.
Study Significance
The study will provide detailed descriptive and comparative information on lower limb and foot characteristics in young ballet dancers and football players.
The findings may help distinguish normal developmental variation and sport-related adaptations from characteristics associated with musculoskeletal symptoms.
Because the study is cross-sectional, it cannot establish causal relationships or predict future injuries.
The results may contribute to future longitudinal studies and inform clinical assessment, injury prevention, training recommendations, and musculoskeletal health promotion in physically active children.
516 studies on the registry are indexed under Musculoskeletal Pain; 128 are open to participants now.
This study's planned enrollment of 148 is below the median of 170 across 137 observational studies indexed under Musculoskeletal Pain.
Browse Musculoskeletal Pain studies →This is the only study on the registry with University hospital of Odense as lead sponsor.
Counted across the registry records on this site, refreshed daily.
The study population consists of Danish children aged 7-16 years participating in organized ballet or competitive football. Approximately 148 children will be recruited, including 74 ballet dancers from the Royal Danish Ballet School and 74 football players from selected Danish football clubs. Participants will belong to predefined age groups (7-8, 11-12, or 15-16 years) and meet sport-specific minimum training requirements.
Clinical findings will be compared with previously collected reference data from 501 typically developing Danish schoolchildren aged 6-17 years. The reference cohort will not undergo additional study assessments.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Enrollment at the Royal Danish Ballet School or a participating Danish football club.
Ballet participants must meet the following minimum training requirements:
Grades 0-1: At least 2 training sessions per week.
Grades 4-5: At least 3 training sessions per week.
Grades 8-9: At least 4 training sessions per week.
Football participants must participate in competitive football, with at least 2 training sessions per week, excluding matches.
Written from both legal guardians and age-appropriate information provided to the child.
Exclusion Criteria:
or infection requiring acute medical treatment.
Acute lower extremity injury or fracture that prevents participation in the study assessments.
Surgery involving the relevant anatomical region within the preceding 3 months.
Neurological or rheumatological disorders affecting lower extremity function.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Children aged 7-16 years recruited from the Royal Danish Ballet School. Approximately 74 participants will undergo standardized clinical assessments of lower limb and foot health, including joint range of motion, rotational profile, foot morphology, functional assessments, and patient-reported outcomes. Participants will meet age-specific minimum ballet training requirements.
Children aged 7-16 years recruited from selected Danish football clubs. Approximately 74 participants who train and compete at a competitive level, with at least two training sessions per week excluding matches, will undergo standardized clinical examinations, functional assessments, three-dimensional foot scanning, and patient-reported outcome assessments.
Passive External Hip Rotation
Passive external hip rotation will be measured in degrees using a goniometer, with the participant in the prone position, the knee flexed to 90 degrees, and the pelvis stabilized. The participant-level mean of right and left hip measurements will be used to compare ballet dancers with the age- and sex-frequency-matched reference cohort. Higher values indicate greater external hip rotation.
Time frame: At the single baseline study visit (cross-sectional assessment)
Ankle Plantarflexion Range of Motion
Maximum passive ankle plantarflexion will be measured in degrees using a standardized clinical examination protocol. Measurements will be compared between ballet dancers and the age- and sex-frequency-matched reference cohort.
Time frame: At the single baseline study visit
Lower Limb Rotational Profile and Joint Range of Motion
Clinical measurements of hip internal rotation, lower limb rotational alignment, and joint range of motion will be recorded in degrees using standardized examination procedures. Measurements will be analyzed descriptively and compared between relevant study groups.
Time frame: At the single baseline study visit
Three-Dimensional Foot Morphology
Foot morphology will be assessed using a Volumental three-dimensional foot scanner. Measurements will include foot length, forefoot width, arch height, instep height, heel width, and other predefined foot dimensions. Bilateral measurements will be recorded.
Time frame: At the single baseline study visit
Pain Intensity - Wong-Baker FACES Pain Rating Scale
1\. Pain Intensity - Wong-Baker FACES Pain Rating Scale Description: Pain intensity will be assessed using the Wong-Baker FACES Pain Rating Scale, an age-appropriate self-reported pain assessment tool. Scores range from 0 (no pain) to 10 (worst possible pain), with higher scores indicating greater pain intensity and therefore a worse outcome. The scale consists of six faces corresponding to scores of 0, 2, 4, 6, 8, and 10.
Time frame: At the single baseline study visit
2. Pain Intensity - Numeric Rating Scale
Pain intensity will be assessed using the 11-point Numeric Rating Scale for Pain (NRS), according to the child's age and ability to self-report pain. Scores range from 0 (no pain) to 10 (worst imaginable pain), with higher scores indicating greater pain intensity and therefore a worse outcome.
Time frame: At the single baseline study visit
3. Anatomical Location of Pain
Description: Pain location will be assessed using a standardized body map on which participants indicate the anatomical region or regions where pain is experienced. Results will be reported as the number and percentage of participants reporting pain in each anatomical region. This is a categorical assessment without a numerical severity score.
Time frame: At the single baseline study visit
Oxford Ankle Foot Questionnaire for Children
4\. Foot-Related Physical Function - Oxford Ankle Foot Questionnaire for Children Description: Foot-related physical function will be assessed using the Physical domain of the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C). This domain consists of six items assessing the impact of foot and ankle conditions on physical activities. Each item is scored from 0 to 4, and the summed score is transformed to a scale ranging from 0 to 100. Higher scores indicate better physical functioning and therefore a better outcome. 5\. School and Play Function - Oxford Ankle Foot Questionnaire for Children Description: School and play function will be assessed using the School and Play domain of the Oxford Ankle Foot Questionnaire for Children (OxAFQ-C). This domain consists of four items assessing the impact of foot and ankle conditions on participation in school and play activities. Each item is scored from 0 to 4, and the summed score is transformed to a scale ranging from 0 to 100. Higher
Time frame: At the single baseline study visit
No study locations are listed for this record.
Plan to share: Yes — De-identified individual participant data underlying the published study results may be made available to qualified researchers upon reasonable written request to the principal investigator after publication. Data sharing will be subject to applicable Danish and European data protection legislation (GDPR), participant consent, relevant institutional approvals, and an appropriate data-sharing agreement. Requests will be evaluated individually based on scientific purpose, data protection requirements, and the risk of participant re-identification. No directly identifiable participant information will be shared.
Supporting information: Study protocol
Time frame: De-identified individual participant data underlying the published results will be available upon reasonable request beginning after publication of the main study results, anticipated in 2029. Data will remain available for five years following publication, subject to applicable data protection regulations and institutional approval.
Access criteria: Qualified researchers may request access to de-identified individual participant data for scientifically justified research purposes. Requests must be submitted in writing to the principal investigator and include a research proposal describing the intended analyses. Access will require approval by the responsible institution, compliance with GDPR and applicable Danish legislation, and an appropriate data-sharing agreement. Data will only be shared if permitted by participant consent and relevant ethical and data protection approvals. No directly identifiable information will be provided.
No publications or documents are linked to this record.
Start is estimated for Jan 2027; primary completion for Dec 2028, 23 months later.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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