Author(s): MYKLEBUST, H., KJELLSTADLI, B., Institution: UNIVERSITY OF STAVANGER, Country: NORWAY, Abstract-ID: 2536

INTRODUCTION:
Figure skaters can improve performance in multi-revolution jumps by increasing the speed of rotation during the flight phase and/or increasing the height of the jumps [1]. Further, skaters spend a lot of time practicing on multi-rotational jumps both on ice and on dry-land, and manufacturers claim that training with rotational and harness training systems can enhance performance [2]. Hence, a non-invasive testing method is needed to quantify the possible effects of rotational and harness training. Therefore, the aim of the present study was to evaluate test-retest reliability and inter-rater reliability of jump height (flight time) in counter-movement jumps (CMJ) and maximal rotational jumps (RJ) performed by young figure skaters.
METHODS:
Nineteen female figure skaters (age: 10-16 years, height: 151.2±6.2 cm, bodymass: 52.5±6.2 kg) were recorded performing two CMJ trials with free arms and three RJ trials using a non-invasive smart-phone APP “My Jump 2” (v.6.1.7 by Dr. Balsalobre-Fernández). Thereafter, two independent experienced scientists analyzed all jumps using the APP, which estimates jump height from flight times. The method has been found valid compared to contact mat [3]. The inter-rater reliability was assessed using typical error (TE) between raters analyzing the same jumps, and test-retest reliability was assessed using TE within skaters repeating the same type of jump. Additionally, coefficient of variation (CV) between skaters was included as a reference of homogeneity of the group. The results are presented as mean ± standard deviation (SD) and the accepted level of TE was set to be < 6 % as previously reported for CMJ [3].
RESULTS:
The results from rater one was CMJ = 29.1 (4.8) cm and 485 (40) ms for jump heights and flight times, respectively, and for RJ was jump heights 23.1 (5.0) cm and flight times 431 (46) ms. Hence, CV between skaters were 17 %, 8.3 %, 21 % and 11 % for CMJ height, CMJ flight time, RJ height, and RJ flight time, respectively. Test-retest reliability showed TE of 3.8 %, 1.9%. 3.7 % and 1.8 % for the same parameters.
Rater two showed 1.4 (1.2) cm higher CMJ height and 3.1 (1.7) cm higher RJ height (p<0.01). This corresponds to 12 (11) ms and 29 (17) ms longer flight times for CMJ and RJ, respectively. The inter-rater TE was 3.9 % and 2.0 % for CMJ height and CMJ flight time, respectively. For RJ the inter-rater TE was 8.9 % for jump height and 4.8 % for flight time.
CONCLUSION:
Inter-rater TE for CMJ was comparable with TE within skaters and of acceptable magnitude. To our knowledge, inter-rater variability for RJ has not been reported previously and was unacceptably high. Hence, using the same rater to analyze RJ is essential for reliability.

References:
1 Mazurkiewicz, A. (2021). https://doi.org/10.2478/pjst-2021-0007
2 Panfilov, V. (2023). https://hdl.handle.net/11250/3078285
3 Gallardo-Fuentes et al. (2016). https://journals.lww.com/nsca-jscr/toc/2016/07000