COVID-19 studies are our top priority. For all other trials, there is a 4-week delay in processing a trial submitted/resubmitted to the ANZCTR and additional delays for updates of registered trials. We appreciate your patience.

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been endorsed by the ANZCTR. Before participating in a study, talk to your health care provider and refer to this information for consumers
Trial registered on ANZCTR

Registration number
Ethics application status
Not yet submitted
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
Vitamin D and muscle strength in female dancers and gymnasts
Scientific title
The effect of 12 months of cholecalciferol supplementation on muscle strength, bone mineral density and respiratory infections in female adolescent gymnasts and dancers
Secondary ID [1] 279679 0
Nil Known
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Nutritional status of adolescent female gymnasts and dancers 285478 0
Muscle strength in female dancers and gymnasts 285479 0
Bone mineral density in female dancers and gymnasts 285501 0
Respiratory infections in female dancers and gymnasts 285502 0
Nutritional status of female dancers and gymnasts 285503 0
Condition category
Condition code
Diet and Nutrition 285658 285658 0 0
Other diet and nutrition disorders
Musculoskeletal 285695 285695 0 0
Normal musculoskeletal and cartilage development and function

Study type
Description of intervention(s) / exposure
12 month supplementation trial with vitamin D3 (cholecalciferol) 1.25mg (50,000 IU) oral tablet, once per month
Intervention code [1] 283947 0
Other interventions
Comparator / control treatment
placebo in the form of oral tablet identical in appearance to the intervention tablet but with no active ingredients, taken once per month
Control group

Primary outcome [1] 286208 0
muscle strength: dominant and non-dominant hand-grip measured using grip-strength dynamometer, quadriceps, hamstrings, knee extensors and flexors using an isokinetic dynamometer (Biodex 4), and jump height using a flight-time calculating jump mat.
Timepoint [1] 286208 0
6 and 12 months
Primary outcome [2] 286209 0
bone mineral density assessed at lumbar spine and proximal femure using dual energy x-ray absorptiometry (DXA) scan (Hologic Discovery A).
Timepoint [2] 286209 0
12 months
Primary outcome [3] 286225 0
Respiratory infections recorded using the Wisconsin Upper Respiratory Symptom survey
Timepoint [3] 286225 0
6 and 12 months
Secondary outcome [1] 295393 0
Iron status - full iron studies from venous blood sample including haemoglobin, serum ferritin, and soluble transferrin receptor
Timepoint [1] 295393 0
Secondary outcome [2] 295411 0
dietary intake from 4-day food diary (analysed using Foodworks software) and validated food frequency questionnaire to assess consumption of iron containing foods.
Timepoint [2] 295411 0
Secondary outcome [3] 295412 0
body composition using dual x-ray absorptiometry, full body scan (Hologic Discovery A)
Timepoint [3] 295412 0

Key inclusion criteria
Participating in gymnastics or dance at least 5 hours per week
Minimum age
13 Years
Maximum age
18 Years
Can healthy volunteers participate?
Key exclusion criteria
Recent (within 2 months) or current use of vitamin D supplements including cod liver oil, smoker

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Participants will be recruited by advertisements in various media. Once enrolled, they will be matched in pairs by (a) type of activity, and (b) age. Participants will receive either a vitamin D supplement or identical (in appearance) placebo pill once per month.Randomisation will be conducted by a 3rd party not associated with the study.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Participants will be randomised using simple randomisation using a computer generated randomisation table (
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Phase 4
Type of endpoint(s)
Statistical methods / analysis

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment outside Australia
Country [1] 4038 0
New Zealand
State/province [1] 4038 0

Funding & Sponsors
Funding source category [1] 284445 0
Name [1] 284445 0
Massey University Research Fund
Address [1] 284445 0
Massey University
Private Bag 102904
North Shore Mail Centre
Auckland 0745
Country [1] 284445 0
New Zealand
Primary sponsor type
Massey University
Private Bag 102904
North Shore Mail Centre
Auckland 0745
New Zealand
Secondary sponsor category [1] 283367 0
Name [1] 283367 0
Address [1] 283367 0
Country [1] 283367 0

Ethics approval
Ethics application status
Not yet submitted
Ethics committee name [1] 286422 0
Health and Disability Ethics Committee - Northern Y
Ethics committee address [1] 286422 0
Private Bag 92-522, Wellesley St

Courier address:
3rd floor, Unisys building
650 Great South Rd
Auckland 1061
Ethics committee country [1] 286422 0
Date submitted for ethics approval [1] 286422 0
Approval date [1] 286422 0
Ethics approval number [1] 286422 0

Brief summary
The discovery of the vitamin D receptor in skeletal muscle suggests a relationship between vitamin D status and muscular function. Although well investigated in the elderly, there are only a small number of cross-sectional studies investigating the relationship between vitamin D status and muscle strength and power in younger populations. Little is known about the implications of deficiency on athletic performance but athletes spending hours training and performing indoors are at risk and may not be achieving their greatest performance potential. Young female gymnasts and dancers have been shown to have low vitamin D status, and additionally are at risk of low iron status related to poor diet, in particular a low energy intake. The bone mineral density (BMD) of this group is also often compromised by poor dietary calcium and protein intake, negative energy balance and delayed menarche. For this study we will recruit 100 adolescent female ballet dancers and gymnasts. They will be randomly assigned to receive either a vitamin D supplement or a placebo for 12 months. Changes in muscle strength and power, and bone mineral density will be the primary outcome measures. Vitamin D and iron status, dietary assessment and body composition will also be measured.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 33580 0
Address 33580 0
Country 33580 0
Phone 33580 0
Fax 33580 0
Email 33580 0
Contact person for public queries
Name 16827 0
Dr Pamela von Hurst
Address 16827 0
Institute of Food, Nutrition and Human Health
Massey University
B27 Eastbourne Road,
Albany, Auckland 0632
Country 16827 0
New Zealand
Phone 16827 0
+64 9 414 0800 ext 41205
Fax 16827 0
+64 9 443 9640
Email 16827 0
Contact person for scientific queries
Name 7755 0
Dr Pamela von Hurst
Address 7755 0
Institute of Food, Nutrition and Human Health
Massey University
Private Bag 102904
Albany, Auckland 0745
Country 7755 0
New Zealand
Phone 7755 0
+64 9 414 0800 ext 41205
Fax 7755 0
+64 9 443 9640
Email 7755 0

No information has been provided regarding IPD availability
Summary results
No Results