ECSS Paris 2023: CP-AP20
INTRODUCTION: The Reactive Strength Index (RSI), defined as the ratio between jump height and ground contact time, is used to assess vertical reactive strength and has been shown to be reliable both during (1) and between training intervals (2). A possible limitation of the RSI is that they only assess reactive strength in the vertical direction, whereas horizontal movements, such as sprinting and CoD in many sports are critical. For example, research has shown that horizontal force generation is a major determinant of sprint acceleration. It is critical to assess the horizontal RSI of horizontal sport athletes. However, the reliability of horizontal RSI derived from different horizontal jumps is unclear. Therefore, the aim of this study was to determine the reliability of sprint bounding and single-leg hopping. METHODS: Thirty-six male college players (21.29 ± 2.16 yr, 180.73 ± 4.02 cm, 79.32 ± 15.27 kg) with well-trained background were recruited in this study. All subjects randomly performed three sprint bounding and single-leg hopping trials in random order. The 2-3 min rest interval was allowed between trials and 5 m interval between tests. For the sprint bounding and single-leg hopping test, participants started with a 5 meter sprint and completed a 5-step forward jump, the contact time and distance was recorded using 10 pair Optojump. The average contact time and jump distance of each jump was used for further analysis. Horizontal DSI was define as the ratio of jump distance and contact time. For the assessment of reliability, and given our repeated measures design, a two-way mixed effects intraclass correlation model was used, where both the reliability of a single (best) trial (ICC [3,1]) and the average of three trials (ICC [3,k]) were assessed. Furthermore, the coefficient of variation (CV %) was also calculated, thus providing us with a measure of relative and absolute reliability. The combination of the ICC and CV% enabled the interpretation of overall reliability as follows: excellent (ICC > 0.9 and CV% < 5), good (0.75 < ICC ≤ 0.9 and CV% < 10), fair (ICC ≤ 0.75 or CV% > 10) and poor (ICC ≤ 0.75 and CV% < 10) (3). RESULTS: For the sprint bounding, good reliability was observed in contact time (ICC = 0.78, CV% = 9.4%), jump distance (ICC = 0.82, CV% = 8.3%), and horizontal RSI (ICC = 0.81, CV% = 3.4%). For the single-leg hopping, contact time (ICC = 0.89, CV% = 9.2%) and jump distance (ICC = 0.89, CV% = 9.2%) exhibited good reliability, excellent reliability was observed in horizontal RSI (ICC = 0.91, CV% = 2.4%). CONCLUSION: Both sprint bounding and single-leg hopping showed accepted reliability, the horizontal RSI derived from single-leg hopping exhibited excellent reliability. Therefore, practitioners can choose sprint bounding or single-leg hopping to assess player‘s horizontal RSI.
Read CV Shang HanECSS Paris 2023: CP-AP20
INTRODUCTION: The functional assessment of sports performance is fundamental throughout an athlete’s season. In various sports such as kayaking, water polo, soccer, and swimming, linear encoders are widely used to monitor the neuromuscular profile (1-4). The linear encoder (MuscleLabTM system, Norway), introduced and validated by Bosco et al., (1995) is a mechanical device capable of measuring time and displacement to estimate respectively the force-velocity and power-velocity ratio. Recently, new encoders and inertial measurement units (IMUs) (e.g., Vitruve, Movella Xsens) have been employed to assess kinematic and dynamic performance in land exercises such as bench press, squat, and prone bench pull. Given these advancements, this study aims to investigate whether these new devices provide data as reliable as the gold-standard MuscleLab system. METHODS: All devices involved in the study (MuscleLab, Vitruve, Xsens) were fixed and calibrated on the barbell. The sample acquisition rate was 100Hz for Vitruve and MuscleLab and 120Hz for Xsens. The test protocol provided six repetitions for each load (from 20,30,40,50 and 60kg) performed by the same athlete (Semi-Pro water polo athlete, Male, 32 years, 1.87m height, 83.5 weight) at maximum velocity, on the bench press (Smith machine). Between each series, an optimal recovery of 4 minutes was considered. The data provided for each device were respectively range of motion [ROM] (m), time (s), mean propulsive velocity [MPV] (m/s), and power (W). Repeated measures analysis of variances (ANOVA) has been used to compare the similar parameters measured by different devices on the same subject. RESULTS: The results showed no significant differences between MuscleLab and Xsens (p > 0.05). However, Vitruve exhibited statistically significant differences with MuscleLab and Xsens specifically for MVP, power, ROM, and time (p < 0.01). Instead, the MVP showed no significant differences between the devices, only at 60kg. CONCLUSION: This preliminary study showed that the parameters measured with Vitruve are different from the MuscleLab linear encoder and Xsens for light loads. Thus, to focus on the velocity and power in the power-based exercises it could be suggested to implement MuscleLab or Xsens.
Read CV Cristian RomagnoliECSS Paris 2023: CP-AP20
INTRODUCTION: Flywheel technology is commonly used in training but remains underutilized for monitoring and testing. Flywheel devices can provide valuable data from mechanical outputs during both concentric and eccentric movements. This systematic review assesses its validity and reliability for evaluating sports performance and limb asymmetry. METHODS: Searches were conducted in PubMed, SPORT-Discus, Google Scholar, and Web of Science following PRISMA DTA guidelines, focusing on keywords related to flywheel testing. RESULTS: The initial search yielded a total of 310 articles (figure 1). The data were imported to the ZoteroTM reference manager software version 6.0.30 (Vienna, Virginia, USA). Duplicates (30 titles) were subsequently removed, either automatically or manually. The remaining 280 articles were screened for their relevance based on their titles and abstracts. Of those, 260 articles were removed, and the full texts of the remaining studies were then inspected. After the automatic search, 20 articles remained for data extraction and further analysis. Following the citation of the list of 20 articles, 7 more eligible titles were suggested, reviewed, and integrated. Consequently, a total of 27 articles were included in the final systematic review. CONCLUSION: Results show that flywheel testing is reliable and valid for the athletic population who when subjects undergo two familiarization sessions and perform with 1-2 pre-repetitions followed by 5-10 recording repetitions with 1-4 sets and 2-3 minutes of rest between sets and with proper equipment (e.g., rotary encoders, force plates, linear encoders, and inertial measurement units) are used (ICC=0.66-0.99, r=0.69-0.97, α=0.85-0.98). Moment of inertia can be customized based on the athletes experience and the type of flywheel device used. Key metrics for assessment encompass speed, force, and power, with peak power being the most commonly employed parameter. Few samples of evidence showed that increased asymmetry in concentric power may negatively affect change of direction performance, emphasizing the need for more high-quality studies. In conclusion, flywheel technology offers valuable insights across various movements, providing strength and power assessment while potentially improving athletic performance and injury prevention. Continued research is vital to explore its effectiveness in diverse athletic contexts.
Read CV Mark, Chung Wai MakECSS Paris 2023: CP-AP20