Inertial measurement units are ‘all g’: Inter-trial reliability when assessing upper and lower body impact loading in artistic gymnastics

Abstract

The magnitude of loading artistic gymnasts experience during training is currently unknown. Inertial measurement units (IMUs) could assess loading, although the reliability of these devices must be established prior to implementation into the training environment. This study aimed to determine inter-trial reliability of using IMeasureU Blue Thunder IMUs to assess upper and lower limb loading when performing foundation gymnastics skills. A secondary aim investigated the effect of raw and filtered acceleration signals on reliability results. Sixteen competitive level artistic gymnasts (male, n = 8; female, n = 8) performed seven gymnastics skills while wearing four IMUs (upper back, lower back, forearm and tibia). The peak resultant acceleration (PRA) during ground contact for all skills was exported from raw and filtered acceleration data (fourth-order zero-lag Butterworth filter with 85 Hz cut-off). Descriptive statistics (median and inter-quartile range), Friedman’s ANOVA, intra-class correlations, coefficient of variation, mean difference and Cohen’s effect sizes were calculated. Overall, the IMU PRA measures showed very good inter-trial reliability, however filtered signals improved reliability statistics for five variables compared to raw. The forearm- and tibia-mounted IMUs demonstrated improved reliability (very good reliability) compared to back positions (good reliability). IMUs are considered reliable devices to measure upper and lower limb loading in gymnastics.

Upper and lower limb impact loading during artistic gymnastics foundation floor tumbling skills

“…All PRA results were sorted into magnitude-based impact categories (Campbell et al, 2021). The impact categories were as follows:…”

“…The gymnast's leading side was determined by observing them perform a round‐off skill (the leg the gymnast used to step into the skill was defined as the leading side). Four IMUs (Blue Thunder, 3‐axis, ±16 g, 1000 Hz; IMeasureU, Auckland, New Zealand) were attached in the following anatomical locations; upper back (T2 vertebrae), lower back (mid‐point between the left and right posterior superior iliac spine), the leading distal tibia (intersection of the middle and distal thirds of the antero‐medial aspect of the tibia) and the leading forearm (intersection of the third and last distal quarters of the dorsal aspect of the forearm; Campbell et al, 2021, 2022). Data from the upper back and the forearm IMUs were analyzed for upper limb impacts, and data from the lower back and tibia IMUs were analyzed for lower limb impacts.…”

“…All PRA results were sorted into magnitude‐based impact categories (Campbell et al., 2021). The impact categories were as follows: (i) very low impact (<4 g), (ii) low impact (4.0–6.9 g), (iii) moderate impact (7.0–9.9 g), (iv) high impact (10.0–12.9 g), (v) very high impact (13.0–15.9 g) and (vi) extreme impact (≥16 g).…”

“…Wearable sensors, such as accelerometers or inertial measurement units (IMU), can be used to measure body segment impact loading when performing gymnastics skills in a training environment (Beatty et al., 2005, 2007; Bradshaw, 2016; Bradshaw et al., 2016; Burt et al., 2007; Campbell et al., 2022). Impact load is typically measured from the peak resultant acceleration with respect to the gravitational constant (9.81 m/s 2 [g]; Campbell et al, 2021, 2022). Peak accelerations (measured at the pelvis) during hand contact have ranged between 4.5 and 7.4 g when performing handstand rebound drills and backwards handsprings (Beatty et al., 2005, 2007).…”

SYSTEMATIC SKILL PRACTICE IN WOMEN's FLOOR EXERCISE

“…This paper analyzes and studies 65 female athletes participating in floor exercises in the National Games. 2 In this paper, the on-the-spot statistical method is used to carry out statistics on the skills and completion of the athletes in the four games. This paper surveyed experts on movement difficulty, movement choreography, and training.…”