The International Olympic Committee recently published its consensus statement on relative energy deficiency syndrome (REDs) in sport which was followed by a similar version for dance by clinicians and researchers in dance. REDs is a complex multisystem syndrome with low energy availability as its foundation. Dancers and gymnasts, particularly in ballet, have long been reported to have body weight issues with an increase prevalence of eating disorders which has been associated with early onset osteoporosis. Combat sports have a similar issue, with athletes needing to "make weight" to compete in their ideal weight category that has lead to similar eating disorder and associated issues to dance. Currently there are no data on REDs prevalence in dance, gymnastics or combat sports and therefore understanding the underlying prevalence of REDs in both these populations will provide important information for both clinicians and coaches to help develop a safe and healthy environment for their dancers and athletes to compete/perform and to be able to retire from sport/dance without an increased risk of osteoporosis. In a few sports and dance genres, some participants might be more prone to a negative health effect referred to as relative energy deficiency syndrome (REDs). This is an energy deficiency relative to the balance between dietary energy intake and energy availability required to support homeostasis, health and activities of daily living, growth and sporting activities that can result in multiple systems being affected including decreases in bone health, energy metabolism, reproductive function, musculoskeletal health, immunity, glycogen synthesis and cardiovascular and haematological health. The purpose of this study is to examine the prevalence of REDs in specific sports (combat sports and gymnastics) and dance genres (ballet and musical theatre). Voluntary participants will be tested three times a year over a 5-year period. This will include an annual dual-energy x-ray absorptiometry and blood tests plus resting energy expenditure and questionnaires three times a year.

Participants will be asked to be available three times for testing over a 12-month period, for a period of 3-years. Their initial test visit will be at a university exercise science laboratory whilst the other testing sessions will occur at their place of work/training.

Each year the initial testing session will include a bone health scan (DXA), a blood sample (2x 5ml samples), a body composition analysis (bioimpedance), resting metabolic rate test and a series of questionnaires. Subsequent test session will include the same tests except the DXA scan unless there is a medical reason to carry out a further scan (two or more bone stress injuries).

The DXA scan, where participants will need to lie still for approximately 20 minutes will monitor body composition, bone mineral density and bone mineral content for the whole body and at the forearm (radius), lower spine (Lumbar 4 and 5) and upper leg (femur). The scan will also look at the ratio between outer (cortical) and inner (trabecular) bone content.

The blood samples will measure a series of markers that have been associated with low energy availability for male and female participants and amenorrhea for female participants.

Anthropometric measurements will consist of body composition analysis will consist of a body composition, stature and body mass. The participant will have their height measured and then stand on bioimpedance scales and hold onto two handles. This will allow changes in body composition changes to be monitored throughout the year without exposing the participant to further radiation from the DXA.

To monitor resting metabolic rate participants will lie down on a bed in a quiet room. They will be fitted with a mask over the mouth and nose that is connected to a breathe-by-breathe gas analyser. They will lie as still as possible for 20-minutes for the test to conclude.

The validated questionnaires (Low Energy Availability Male Questionnaire, Low Energy Availability Female Questionnaire, Health questionnaire) will focus on sleep quality, general health, attitudes towards food and eating, perceptions of energy availability, and mood.

Basic injury incidence data will be provided by the participant's medical team through out the monitoring period. Injury data will consist of location, type and severity of each injury.

Participants' injury incidence and aetiology will be monitored by their club's/company's medical teams and summarised data provided to the research team via a signed medical release agreement. REDs prevalence will be analysed by the research team in conjunction with the participants' medical teams and for those diagnosed with the syndrome the relevant management plan will be put into place for their safe return to activity.

Inclusion Criteria:

• Full-time training at either a NGB centre, dance company, vocational dance school or academy
• Engaged in full-time training at start of project

Exclusion Criteria

• Not engaged in full-time training
• Injury preventing engagement in training

Dancers: ballet, contemporary dance and musical theatre Combat sports: judo, karate, taekwondo Gymnastics: artistic

All anonymised data will be shared via figshare

Protocol and statistical analysis plan will be available pre data collection Data will be available at point of publication

All data will be made available in line with Open Science protocols