The countermovement jump (CMJ) assessment is widely employed for monitoring sports performance, traditionally relying on heavy and expensive force plates to extract performance variables like jump height and peak force. Inertial measurement unit (IMU)-based approaches and mobile applications have been developed to analyse CMJ performance with cost-effective devices, but they still require technical expertise and manual annotations during operation. We developed a new camera-based pipeline that can measure CMJ performance automatically by utilising computer vision techniques and biomechanical approaches from video captured by a single uncalibrated camera. Human segmentation and pose estimation techniques are used to understand the movement of the centre of mass and take-off and landing times. Combined with the biomechanical principles of object parabolic motion and inverse dynamics, the force-time data can be estimated for extracting CMJ performance variables. We recruited 77 elite athletes (29 females; height: 170.0 ± 9.0 cm; mass: 72.2 ± 17.7 kg) to evaluate the developed method against a commercial force platform. The developed method enables fully automatic CMJ analysis for both force-time data and performance variables from video captured by a camera without calibration. The results showed superior correlations (R > 0.7) and high reliability (%CV < 10 %) for most CMJ variables compared to the IMU-based approach. This approach automates CMJ analysis, offering more variables than existing mobile apps while reducing the technical demands of IMU-based methods. It streamlines assessment, making it ideal for large-scale cohort studies. Grounded in biomechanics, it enhances sports and health monitoring, enabling data-driven optimisation of human performance.

Purpose : Optimizing performance while managing training load (TL) is a constant goal in high-performance sport. However, there is limited evidence on how year-long TL variations influence jumping and sprinting characteristics in collegiate basketball. This study aimed to analyze changes in TL and physical performance in a Taiwanese collegiate men’s basketball team during a full year-long season. Methods : Ten male basketball players who participated in a collegiate basketball training program were assessed using the countermovement jump (CMJ) and 20-m sprint test before the off-season (T1) and after the season (T4). In addition to the pretest and posttest, CMJ was assessed after the preparation phase (T2) and the precompetition phase (T3) to understand training adaptations. Session rating of perceived exertion was collected after each training session to calculate TL. Monthly TL values were then compared with those of the preceding month. CMJ, sprinting, and TL differences between time points were compared. Significance level was set at P < .05. Results : CMJ height significantly increased at T2 ( P = .04) and was maintained until T4. Twenty-meter sprint time did not significantly differ between T1 and T4. Monthly TL significantly decreased between off-season and preseason, as well as between off-season and precompetition phases ( P < .001). Conclusions : These findings suggest that the athletes improved CMJ and maintained sprint performance throughout the training plan. Tapering achieved through the manipulation of TL may improve performance outcomes before important competitions.

Background/Objectives: The underlying mechanisms of taekwondo-specific jumping ability among different competition levels are still unknown. This study aimed to compare vertical and horizontal stretch-shortening cycle (SSC) performance between athletes of different competitive levels and examine the relationships of force and power production abilities between those two directions in Taiwanese collegiate-level male taekwondo athletes. Methods: Seventeen male collegiate taekwondo athletes were divided into two groups: medalists (MG, n = 8) and non-medalists (NMG, n = 9); both groups performed countermovement jumps (CMJ) on a force platform and single-leg lateral hops (SLLHs) via an optoelectronic measurement system. Eccentric and concentric phase measures from CMJ and distant and temporal variables of SLLH were collected for further analysis. Results: The MG achieved statistically superior jump height (JH), concentric peak velocity, eccentric peak force, force at 0 velocity, and eccentric displacement than NMG (d = 1.05–1.36). Although non-significant differences showed in SLLH variables, MG had better results than NMG (d = 0.40–0.84). Moderate relationships were identified between SLLH step 1 and JH, reactive strength index modified, peak concentric power, and peak concentric velocity of CMJ (r = 0.50–0.57, p < 0.05). Furthermore, step 2 ground contact time and lateral reactive strength index from SLLH were associated with CMJ peak eccentric force, peak concentric force, and force at 0 velocity (r = 0.53–0.59, p < 0.05). Conclusions: Taekwondo MG achieved superior CMJ and SLLH performance. In addition, jumping abilities in vertical and lateral directions shared specific underlying mechanisms in collegiate male taekwondo athletes.

While the influence of the load on mechanical outcomes has been investigated in weightlifting pulling derivatives, knowledge of these relationships in overhead pressing derivatives remains limited. To address this gap, this study examined the effects of varying loads on the force-time characteristics associated with peak power output in the behind-the-neck push jerk (BNPJ). Sixteen recreational male athletes were recruited and performed three repetitions of the BNPJ at 40%, 50%, 60%, 70%, and 80% of their 1RM. Mean system velocity (MSV), propulsive phase time (Time), peak force (PF), mean force (MF), peak power (PP), mean power (MP), the impulse and depth were calculated from force-time data during the propulsive phase and compared across loads. A series of one-way repeated measures analysis of variance (ANOVA) was used to compare the differences in each variable across intensities. The level of significance was set at p ≤ 0.05. Except for MSV, all variables progressively increased with loads. PF, MF, PP, MP, and the impulse were greatest at 80% 1RM with small to large significant differences between other intensities (p = 0.00–0.02, Hedge’s g = 0.26–2.49). There were no significant differences between 70% and 80% 1RM in PV (p = 0.35, g = 0.18), but there were significant differences between 80% 1RM and 40%, 50%, and 60% 1RM (p = 0.01–0.05, g = 0.14–0.64). Prescribing the BNPJ at 80% 1RM is beneficial in enhancing power and force output.

Body mass (BM) can be used to prescribe loads for some weightlifting derivatives, as an alternative to the one-repetition maximum (1RM). However, the effectiveness of this method has not been investigated in weightlifting overhead pressing derivatives. The primary aim of the study was to investigate the effect of loads determined with percentages of 1RM and BM on kinetic and kinematic characteristics in the behind-neck push jerk (BNPJ). Sixteen recreational male athletes were recruited and performed 3 repetitions of the BNPJ from 40% to 80% of their 1RM and BM, respectively. Two force plates were used to collect kinematic (peak velocity, mean velocity, phase time) and kinetic variables (peak force, mean force, peak power, mean power, and impulse) in the concentric phase. A two-way repeated measures analysis of variance assessed the interaction and the main effect (approaches and intensities) on the dependent variables. The level of significance was set at p ≤ 0.05. No significant interactions existed between the approaches and intensities in all variables. The main effect approach was not significant in all the kinematic variables, but significant intensity main effects were found. Significant approach and intensity main effects were found in all kinetic variables. All kinetic variables were greater in the 1RM-based approach compared to the BM-based approach. BM can serve as a practical alternative to 1RM for load prescription in the BNPJ when targeting kinematic characteristics. However, 1RM-based loading may be more suitable for maximizing kinetic outputs.

Velocity loss thresholds (VLT) and rating of perceived exertion (RPE) are two autoregulatory (AR) methods often implemented in resistance training. To provide coaches with a clearer understanding of the interplay of the two different methods, the aim of this study was to investigate the effects of 10%, 20%, 30% and 40% VLTs on RPE and repetition characteristics during the back squat exercise. 17 resistance-trained males performed one repetition max (1RM) back squat testing to determine individual load-velocity profiles. In a subsequent session, subjects completed sets to failure at 85% 1RM with 10%, 20%, 30%, and 40% VLTs. Kinematic outputs were measured with a linear position transducer, and RPE was recorded after each set. Significance was set at p < 0.05. Linear mixed models revealed significant effects of VLT on RPE and repetitions, with analyses demonstrating that RPE was significantly higher at greater VLT. Additionally, there was substantial inter-subject variability in the number of repetitions completed at each threshold. Collectively, these findings demonstrate that VLT significantly influence both perceived exertion and repetition characteristics and can help regulate the proximity to failure and exertion of athletes. Furthermore, the heterogenous response of RPE and repetitions between subjects suggests that VLT may induce varying levels of perceived exertion and repetition totals. This may be due to individual factors such as muscular endurance and ability to gauge exertion. Thus, AR prescriptive methods (e.g., RPE or VLT) should be used alongside traditional prescriptive methods to guide training and support the adjustment of training loads and volume.