The Greek Acute Dance Injuries Registry

All the participants will be assessed by a registered physiotherapist either positively (incidence of the AV) or negatively (non-incidence of the AV) for the following AV: knee valgus, knee varum, hallux valgus, splay foot, forefoot adduction, hindfoot varum, hindfoot valgus, longitudinal arch cavus, longitudinal arch planus, forward head, cervical lordosis, thoracic kyphosis, scoliosis, lumbar lordosis, and knee hyperextension, according to past publications (Gamboa et al, 2008; Steinberg et al, 2012).

SF-36 is used to assess Quality of Life (QoL) and consists of eight physical and mental health domains: Physical Functioning (PF), Role Physical (RP), Bodily Pain (BP), General Health (GH), Vitality (VT), Social Functioning (SF), Role Emotional (RE), and Mental Health (MH). Subscales evaluate health between 0 and 100, and 0 indicates "bad health", 100 indicates "good health". It will be used to assess QoL and to study construct validity of the DFOS-Gr, similar to that tested in the english (Bronner and Urbano, 2018), spanish (de-la-Cruz-Torres et al, 2020), and italian (Contri et al, 2021) version.

Beighton-score is 9 point score for the assessment of hypermobility. It investigates the presence of hyperlaxity (yes = 1, no = 0) at both wrists, the fifth metacarpo-phalangeal joints, elbows, knee joints, and the lumbosacral joints. Sum of the items ranges from 0 to 9 points, with higher scores indicating greater joint laxity.

TT (also known as Iliacus Test or Iliopsoas Test) is used to measure hip flexors (iliopsoas muscle group, rectus femoris, pectineus, gracillis, tensor fascia latae, and sartorius) flexibility. Participants will be assessed by a registered physiotherapist either positively (non-flexible hip flexors) or negatively (flexible hip flexors) from supine position on the examination table. Participant holds one knee flexed on his/her chest and lowers the tested limb toward the table. Test is positive when the tested hip joint is flexed, and negative when is hyperextended with the tested limb's thigh under the table.

SLR is used to measure hamstring (semimembranosus, semitendinosus and biceps femoris) flexibility. Participants will be assessed by a registered physiotherapist either positively (non-flexible hip flexors) or negatively (flexible hip flexors) from supine position on the examination table. Participant actively flexes his tested hip joint with the knee extended and the non-tested limb totally extended on the table. Test is positive when the tested hip joint is flexed more than 90 degrees, and negative when it is flexed less than 90 degrees.

OT is used to measure tensor fascia latae (TFL) flexibility. Participants will be assessed by a registered physiotherapist either positively (non-flexible TFL) or negatively (flexible TFL) from lateral decubitus position. The evaluator flexes the knee of the tested limb at 90 degrees and abducts and extends the hip until it is level with the trunk. Only gravity then acts to the tested hip joint bringing it on the maximum possible passive adduction. Test is positive when tested limp's knee is off the table, and negative when it is on the table.

For the registration of the prevalence of possible cardiac clinical signs, an ECG will be executed and clinically interpreted by a registered cardiologist.

Five assessments with a goniometer in both sides will be executed, according to past research (Yin et al, 2019): passive range of dorsiflexion from supine position, passive range of hip external and internal rotation from prone position, passive range of hip horizontal abduction from supine position, and active range of hip external rotation from standing position (first feet ballet position), with higher ranges of motion indicating greater flexibility.

The participant is asked to lie facing down and rise on their elbows and toes while keeping the body in a straight line. The total time is recorded for the assessment of the core region muscles strength and endurance (more often called as "core stability"). The time is stopped if the participant lowers or lifts his/her body.

The participant is asked to lie on his/her side on the elbow with the lower limbs in full extension. Participant is asked to lift the lower limbs so that the hips and back are aligned and mentain this position. The total time is recorded for both sides, right and left, for the assessment of the lateral trunk flexor muscles strength and endurance (more often called as "lateral core stability"). The time is stopped if the participant lowers or lifts his/her pelvis.

The participant is asked to stand on one foot while he/she raises the other foot off the floor. The total time is recorded for both sides, right and left, for the assessment of static balance. The time is stopped if the supported foot is moved away from the starting position and/or the non-supported foot touches the floor. Rahman's et al (2017) categorization will be used: great (>50''), good (40''-50''), typical (25''-39''), acceptable (10''-24''), and poor (<10'') balance.

BI will be used to assess body mass (kg), body mass index - BMI (kg/cm^2), fat mass (percentage), and muscle mass (kg).

AST is a variation of Kasch Step Test for the aerobic capacity evaluation. Participant is asked to step up and down on a 0,305 meter step for 3 minutes following an audible metronome adjusted in 112 beats*min^-1. Resting heart rate (RHR) before the test and Heart Rate Recovery (HRR) one minute after the test finish will be assessed. HRR score closer to RHR score indicates greater aerobic capacity, according to Darr et al (1988).

DTSI is a dance-specific motor control instrument, which assesses the dancer's motor control for different body regions during the execution of 3 dance movements: grand plié à la seconde [pelvis, hips, knees, and feet (0-4 points)], dèveloppé à la seconde [pelvis, turn-out, hips, knees, feet (0-5 points), and sautés au premier position [pelvis, hips, knees, feet (0-4 points)]. One point is added for each incorrect body region's execution. A total score from 9 to 13 points indicates a poor technique, from 5 to 8 points indicates a moderate technique, and from 0 to 4 points indicates a good technique.

DFOS is a 14-item lower extremity and low back likert-scale questionnaire, which assesses dancer's ability to accomplish activities of daily living (ADL) and dance-specific movements. It has 2 subscales; the first consists of six items regarding ADL and scored with a total of 40 points, and the second consists of eight items regarding technique and scored with a total of 50 points. The DFOS-total is both sections combined, for a possible score of 90 points, and it is multiplied by 100 to be normalized to a percentage (Bronner et al, 2019).

MFI is a 20-item instrument to measure five dimensions of fatigue (general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue), each item is scored from one to five and each dimension consists of five items. The dimensional score consequently ranges from 4 to 20 (a higher score indicates more fatigue).

Normal score: 0-9, Mild score: 10-12, Moderate score: 13-20, Severe score: 21-27, and Extremely severe: 28-42.

Normal score: 0-6, Mild score: 7-9, Moderate score: 10-14, Severe score: 15-19, and Extremely severe: 20-42.

Normal score: 0-10, Mild score: 11-18, Moderate score: 19-26, Severe score: 27-34, and Extremely severe: 35-42.

PSS is a 1-item likert-scale questionnaire to assess the level of dance performance satisfaction, as it is used in past studies (Dotti et al, 1998; Yannakoulia et al, 2004). Total score ranges from 1 (i am not satisfied at all) to 10 (i am absolutely satisfied).

The EAT-26 is a 26-item scale. Items are presented in a 6-point Likert-scale ranging from 1 ("never") to 6 ("always). The total score is obtained re-coding scores as follows: scores from 1 to 3 are re-coded as 0, 4 is re-coded as 1, 5 as 2, and 6 is recoded as 3. The only exception is item 25 whose answers score as follows: 1 as 3, 2 as 2, 3 as 1, and 4 to 6 as 0. The EAT-26 total score ranges from 0 to 78. A higher score indicates greater levels of attitudes and behaviors related to eating disorders.

Greek version of ABQ is a 13-item scale that evaluates the 3 constructs of athlete burnout: emotional or physical exhaustion, reduced sense of accomplishment, and sport devaluation. Each item is rated on a 5-point Likert scale ranging from almost never (1) to almost always (5). To calculate average scores for each construct of athlete burnout, subscale scores were summed individually and divided by 5. Higher scores indicate higher burnout levels.

DFS-2 is a 36-item scale of a 5-point Likert-scale questionnaire ranges from 1 (totally disagree) to 5 (totally agree), with four items for each one of the following nine components (also known as factors and dimensions): Challenge-Skill Balance (CSB), Merging of Action-Awareness (MAA), Clear Goals (CG), Unambiguous Feedback (UF), Concentration on Task at Hand (CTH), Sense of Control (SC), Loss of Self-Consciousness (LSC), Transformation of Time (TT), and Autotelic Experience (AE).