Overuse injuries are common among competitive Norwegian rhythmic gymnasts with a mean weekly prevalence of 37% [95% CI: 36 - 39%] and incidence of 4.2 new overuse injuries [95% CI: 3.6 - 4.9] per gymnast per year (Gram, M., Clarsen, B., & Bø, K., 2021). The knees, lower back and hip/groin were the most common injury locations. It has been postulated that reduced physical capacity (e.g strength, flexibility, stability) in the knees, lower back and hip/groin can increase the risk of injuries in rhythmic gymnastics.

In addition, more than 30% of the Norwegian rhythmic gymnasts experience urinary incontinence (UI), and 70% reported that UI negatively affected sports performance (Gram, M., & Bø, K., 2020). Few of the rhythmic gymnasts had any knowledge about the pelvic floor.

Hence, this assessor blinded cluster randomized controlled trial aims to find out whether the implementation of exercises targeting reduced physical capacity and pelvic floor dysfunction can prevent/reduce the prevalence of overuse injuries and UI.

BACKGROUND

Norwegian rhythmic gymnasts have high prevalence and incidence of overuse injuries. Previous research on risk factors related to injuries in rhythmic gymnastics (RG) has implied that high weekly training load, hypermobility, poor technic and inappropriate training load increase the risk of injuries. A prospective study also found that previous injury increased the risk of injuries substantially (Gram, M., Clarsen, B., & Bø, K., 2021). Hence, injury prevention interventions should start at an early age to avoid the first injury. In addition, since the aetiology and mechanisms of injuries are multifactorial, with a well described complex interaction of internal and external risk factors making a gymnast more or less prone to sustain an injury, there might be a need to assess some internal risk factors more thoroughly. The modifiable internal risk factor physical capacity, e.g. strength, flexibility, stability, might be of particular interest, since lack of physical capacity can be thought of as a potential underlying cause in all of the above-mentioned risk factors. In addition, it is well known how persistent lack of physical capacity relative to the requirements in a sport might lead to injuries. With knees, lower back and hip/groin as the most commonly reported injury locations, clinical assessment of strength, flexibility and stability in these locations has been conducted in a cross-sectional study before this randomized controlled trial (RCT). Reduced physical capacity revealed in the cross-sectional study will be targeted/brought forward in the exercise program in the RCT.

The most common types of pelvic floor dysfunctions (PFD) are urinary incontinence (UI), anal incontinence (AI) and pelvic organ prolapse (POP). UI has high prevalence among female athletes participating in sports including jumping and running (high impact). A prevalence of 80% was found in young, nulliparous high-level trampoline jumpers in Sweden (Eliasson et.al., 2008). The prevalence among Norwegian rhythmic gymnasts was >30%, while Thyssen et.al. found that 56% of female Danish artistic gymnasts and 43% of dancers reported UI. UI negatively affects sports performance, and symptoms at young age is a risk factor of future UI developing during pregnancy and after childbirth. Hence, interventions toward prevention and treatment is necessary. While strength training of the pelvic floor muscles has 1A level of evidence/recommendation to treat UI in the general female population, and has no known adverse effects, there is little knowledge of this among young female athletes and dancers. Search on PubMed revealed only one RCT assessing the effect of pelvic floor muscle training on UI in female athletes. Ferreira et.al. randomized 32 female volleyball players to 3 months of pelvic floor muscle training or control, and found statistically significant improvement in the exercise group in frequency of leakage and urine loss measured during physical activity(p< 0.001). Hence, there seem to be a potential for prevention and treatment also in athletes exposed to heavy load towards the pelvic floor.

AIMS

The aims of this RCT are to investigate if implementation of prophylactic exercises targeting reduced capacity and pelvic floor dysfunction can prevent/lower the prevalence of overuse injuries and UI among Norwegian rhythmic gymnasts.

STUDY DESIGN AND METHODS

All rhythmic gymnastics clubs that are members of the Norwegian Gymnastics Federation and have gymnasts fulfilling the inclusion criteria will be invited to participate. The clubs are then randomly allocated to either an exercise or control group. Randomization will be provided by a person not involved in assessments of outcome.

All gymnasts in both groups will answer the "Oslo Sports Trauma Research Center Questionnaire on Health Problems" (OSTRC-H2) at baseline (including a part with background questions) and once each month during the intervention period. In addition, the gymnasts will answer the "International Consultation on Incontinence Questionnaire-Urinary Incontinence Short Form" (ICIQ-UI-SF) before and after the intervention period. After the intervention, the intervention group will answer the Global rating of change (GRC), a numerical 11-point scale to assess self-experienced effect and progress related to overuse injuries and UI.

Inclusion Criteria:

• All rhythmic gymnastics clubs that are members of the Norwegian Gymnastics Federation and have gymnasts fulfilling the inclusion criteria will be invited to participate.
• Female rhythmic gymnasts ≥12 years of age training ≥3 days per week

Exclusion Criteria:

• Female rhythmic gymnasts <12 years of age training <3 days per week

Rhythmic gymnastics is a female sport in Norway. Hence, the study will only include female gymnasts.