Accuracy of flight time and countermovement-jump height estimated from videos at different frame rates with MyJump

Abstract

Recent improvements in smartphone video technology may provide sufficient accuracy for estimation of jump height via flight time determined from video recordings of vertical-jump tests. The aim of this study is to evaluate the accuracy of jump height estimated from videos at different frame rates. High-definition videos of 10 young adults (6 males, 4 females) performing 5 countermovement jumps were recorded at a frame rate of 1000 Hz and transcoded to frame rates of 120, 240, and 480 Hz. Flight time in the videos was assessed independently by three observers at each of the four frame rates with MyJump. Flight time and jump height were analyzed with mixed models for estimation of means and of standard deviations representing technical error of measurement (free of within-subject jump-to-jump variability) at each frame rate. The four frame rates and three observers produced practically identical estimates of mean jump height. The technical errors at 120, 240, 480 and 1000 Hz were respectively 3.4, 1.8, 1.2 and 0.8 ms for flight time, and 1.4%, 0.7%, 0.5% and 0.3% for jump height. Assessed relative to either differences in jump height between elite football players (standard deviation of ~12%) or the smallest expected test-retest variability (typical error of ~3%), the technical error was substantial at 120 Hz but negligible at 240 Hz or higher. In conclusion, use of frame rates above 240 Hz to estimate jump height with MyJump will not improve accuracy substantially.

Concurrent Validity and Reliability of In-Field Vertical Jump Performance Measures on Sand Surfaces

“…However, when the results of Rater 3 were removed, the absolute agreement between the expert raters was excellent . These findings contrast with a study by Pueo et al (33), who found no difference in reliability between trained and untrained raters when measuring jumps on firm ground, highlighting the challenges of measuring jumping performance on sand surfaces. Still, with the help of an adequate protocol for takeoff and landing detection, MyJump2 provides reliable results, highlighting the applicability of coaches to obtain data on sand surfaces.…”

Common Vertical Jump and Reactive Strength Index Measuring Devices: A Validity and Reliability Analysis

“…At the same time, one of the main disadvantages of this application is that it requires the user to visually select the video frames of the takeoff and landing moments, which may lead to an interrater disagreement and thus potentially inaccurate results. However, a recent study showed good agreement between trained and untrained raters for jump height assessment, indicating that the video application has good interrater reliability (44).…”

Test–Retest and Between–Device Reliability of Vmaxpro IMU at Hip and Ankle for Vertical Jump Measurement

“…Reliability of the instrument has been analyzed in a test–retest design in various studies [ 54 ]. For Vmaxpro , reliability on the hip was determined to be similar (ICC = 0.98; CV = 6.1%) compared to other studies where the device was placed on the hip (ICCs range: 0.86 to 0.98; CVs range: 3.1% to 10.7%) [ 15 , 16 , 19 , 21 , 55 ]. Placing the IMU on the forefoot showed better reliability figures (ICC = 0.89 to 0.90; CV = 4.1% to 4.3%) [ 18 , 56 ] than the Vmaxpro on the ankle in this study (ICC = 0.79; CV = 8.1%).…”

“…These factors can be so significant that they might mask the variability of the instrument. To mitigate this, averaging multiple jumps in the data analysis instead of using raw data can help avoid uncertainty [ 55 ].…”