Relationship between lower body muscle strength and explosiveness and degrees rotated in the double axel figure skating jump Michaela Kristensson Master Degree Project Main field of study: Sports Science Credits: 30 credits Semester/Year: 2020 Supervisor: Glenn Björklund Examiner: Marko Laaksonen Course code/registration number: IV005A Acknowledgements I would like to thank my supervisor Glenn Björklund for guidance and feedback throughout the writing of this thesis. Special thanks to Nanne Olsson and the staff at the Blekinge health arena for all the help preparing and executing the tests. Also, I would also like to thank all the skaters who participated in the study. Without you, it would not have been possible. Abstract Axel is a mandatory jump that figure skaters perform in their routines. All jump needs to be fully rotated to reach full points. This study investigated factors that can affect the amount of degrees rotated in the double axel jump. The purpose was to see if there is a link between off- ice performance and on-ice performance with the hypothesis, that figure skaters with higher lower body muscle strength and power off-ice will increase the ability to perform jumps with 2.5 turns or more on the ice. 13 participants first performed double axel (2A) on the ice, measuring entry speed and the amount of degrees rotated. Then the participants performed three different physical tests, back squat, maximum rotational speed and countermovement jump with arms at the test lab. The tests were made with light mat, camera and software for analysis. There was a significant (α = 0.05) correlation between degrees rotated and maximum rotational speed off-ice (r= 0.670, p= 0.012), degrees rotated and entry speed to the jump (r= 0.600, p= 0.030). There was also a moderate correlation between time in the air in double axel and two feet and countermovement jump with arms (r= 0.631 p=0.021). The conclusion, significant correlation was found between the rotational velocity off ice and degrees rotated in 2A on ice as well as entry speed and degrees rotated in 2A. Table of Contents Background 1 Figure skating 1 Technical rules for jumps 1 Biomechanics and technique of the axel jump 2 Strength and power in figure skating 4 Limiting factors 5 Aim 5 Hypothesis 5 Methods 5 Participants 5 Ethical consideration 6 Study Design 6 The testing procedure 6 Materials 9 Data analysis and statistics 9 Result 9 Discussion 11 Conclusion 15 References 16 Attachment 1. Material 18 Attachment 2. Pearson correlation matrix 19 Attachment 3. Multiple regression 20 Background Figure skating Figure skating has several different disciplines, single skating being one for them. In single figure skating the competition program consists of various elements and components that are judged during performance of the program. The skaters perform two different programs, short program and free program, which together gives the total score. The score from each program is divided into two categories, elements score and program components. The element score includes jumps, spins, step sequences and choreographic sequences. The program components consists of five categories, where each category will be judged individually and then combined into a total (International Skating Union, 2018a). The greatest evolution in figure skating in recent years concerns the increased difficulty of the jumps. The world's top men figure skaters all use quadruple jumps, while the ladies more often use triple axel (3A) and some of the quadruple jumps (Gajanan, 2018; Hersh, 2019). In women's senior class competitions required elements in the short program for ISU competitions (International Skating Union) are double axel (2A) or triple axel (3A), one solo triple jump and a combination of two jumps where at least one of them must be a triple jump (International Skating Union, 2018a). This means that the 2A is the easiest jump, that is valid and for which the skater can earn points from during the short program. In the free skating program, the axel jump is the only jump which is mandatory to perform at least once, but the number of revolutions in the air is optional. Only 18% of the skaters in Novice girls U15A (age between 13 and 15 years old), Junior A Lady and Senior A Lady in Sweden performed two or more clean 2A jumps at competition during the season 2018-2019 (www.skatesweden.wehost.se/18-19/) Technical rules for jumps The technical specialist judges are judging whether or not the jump has the sufficient amount of rotations in the air before the toe pick touches the ice again. The Technical Panel Handbook in single skating by ISU (International Skating Union, 2018b) defines that a jump is judged as under-rotated if it is “missing rotation of ¼ revolution or more, but less than ½ 1 revolution”. It is marked with a < in the judges score protocol and is penalized with point reduction. If the jump is missing more than ½ revolution, it is downgraded to a level below the attempted jump and marked << in the protocol (International Skating Union, 2018b). For example, an attempt on 3A with more than a ½ revolution left will say 3A<< and has the value for a 2A. In addition to the loss of points for one level down, the judges also rate the execution of the jump and this is called grade of execution (GOE). GOE is a scale between -5 to 5, where 0 is the base value of the jump. The requirement to reach base value is a normal jump without mistakes, but not particularly well executed either. There are bullet points indicating what makes the quality good or bad. For every bullet that applies to the jump, the grade increases or decreases by one point on the scale. Some events, like falling, automatically yields -5 as score for the jump (International Skating Union, 2018b). Due to all this, it is important that the jumps are rotated all revolutions required in order to achieve the best possible score. In the case of 2A and 1A, fully rotated 2A is worth three times as much as an attempt on 2A which is downgraded (2A<<) to a value of a 1A. Biomechanics and technique of the axel jump The name of the jump originates from the Norwegian figure skater Axel Paulson, who was the first skater to perform the jump at competition. The axel jump normally starts with a preparation on backward outside edge but can vary between skaters. The blade on figure skating skates is cup-shaped and has two edges, outside and inside edge. Outside edge is when the little toe is closest to the ice and inside edge is with the big toe closest. The axel jump can be divided into 3 different phases, the take-off, air phase and landing. It is executed by transitioning to forward outside edge on either left or right foot depending on which direction the skater prefers to do the rotation from. After the air phase the skater needs to perform a landing with balance, executed on the opposite leg from the take-off. The take-off phase can in turn be divided into glide, transition and pivot phase. The glide- phase starts on forward outside edge, standing on one foot, the active leg. The other leg, the free leg, is in the air, starting behind the body. The free leg works together with the arms in a forward motion. In this early stage, there is only horizontal speed that affects the skater when gliding forward. A positive relationship between skill level and higher horizontal entrance speed has been seen (Albert and Miller, 1996). There is a slightly negative vertical speed (Albert and Miller, 1996) because of the knee flexion and the start of stretch-shortening cycle, the same as can be seen at counter movement jump (CMJ). 2 The transition starts when the free leg passes the active leg together with the arms. The free leg passes and moves forward and the free leg’s knee bends upwards at the same time as the extension of the active leg starts (King, Arnold and Smith, 1994; Albert and Miller, 1996). The direction of the centre of mass (CoM) starts to move upwards and at the end of the transition phase the CoM simultaneously also moves forward to the toe pick which makes the blade turn even more into the circle (Albert and Miller, 1996). The free extremities, arms and leg, contribute 8 to 10 % of the force impulse of the vertical moment of the body during the take-off (King, 2005). As the vertical speed starts to get positive, the horizontal speed decreases. At the end of transition the rotational speed also gets positive. When performing 2A the horizontal speed decreases more than when performing 1A (Albert and Miller, 1996). During the pivot phase the horizontal speed decreases even more due to that the toe pick is in the ice during almost the whole phase. After the take-off the direction and velocity are fixed and cannot be changed, due to the law of conservation of momentum (Blazevich, 2007). It has also been found that initial rotation rate when entering the 2A was higher than for 1A (Albert and Miller, 1996). King, Arnold and Smith, 1994, discussed whether the increased rotational speed in the air depends on increased angular momentum at the take-off or decreased moment of inertia due to a tighter position in the air. In a study comparing 1A, 2A and 3A, the skater with the most open position in the air had the slowest rotation velocity and the skater with tightest position rotated the fastest (King, Arnold and Smith, 1994).