Journal of Human Kinetics最新文献

We sought to compare the spine and lower limb alignment using inertial measurement units (IMUs) in athletes with and without low back pain (LBP). Fifty junior gymnasts were divided into two groups: those with (n = 12) and without LBP (n = 38). IMU sensors were placed throughout the body. Participants were instructed to perform back-bending. The movements of shoulder, thoracolumbar, lumbosacral, hip, and knee joints were assessed. Additionally, differences between thoracolumbar and lumbosacral joints were evaluated. In the sagittal plane, lumbosacral extension was greater in the no-LBP group (37.7° ± 13.6°) than in the LBP group (24.6° ± 20.4°, p < 0.05, d = 0.85). Thoracolumbar extension was similar in the no-LBP (74.1° ± 14.4°) and LBP groups (84.5° ± 20.4°, p > 0.05, d = 0.66). The difference between thoracolumbar and lumbosacral extension was 36.4° ± 22.4° in the no-LBP group and 59.8° ± 34.2° in the LBP group, which was statistically significant (p < 0.05, d = 0.41). Hip extension was greater in the no-LBP group (10.7° ± 7.1°) than the LBP group (5.5° ± 7.6°, p < 0.05, d = 0.73). In the frontal plane, diminished lumbosacral joint lateral flexion was observed in the no-LBP group (5.8° ± 4.6°) compared to the LBP group (11.1° ± 8.3°, p < 0.05, d = 0.45). Junior gymnasts with LBP demonstrated reduced ranges of motion in hip and lumbosacral extension, along with further extension of the thoracolumbar beyond the lumbosacral joints while back-bending. Additionally, lateral flexion was observed at lumbosacral joints.

An excessive pelvic tilt in the late swing phase of sprinting may be associated with an increased risk of hamstring injury. Nevertheless, research including female athletes is scarce. Furthermore, it is essential to validate simple on-field methods. This study consisted of two experiments. Experiment I assessed the validity of two 2-D video-based methods: i) the kick-back score calculated from thigh angles at the toe-off and the touchdown; and ii) the pelvic tilt estimated by a line connecting two markers on the pelvis. Twelve soccer players sprinted for 30 m, and 3-D motion capture data and 2-D sagittal plane video were recorded. Experiment II aimed to compare the above 2-D methods in recently injured (n = 7) and non-injured (n = 18) professional female soccer players. In Experiment I, no correlation was found between the kick-back score and the pelvic tilt assessed using 3-D motion capture (rho = -0.224, p = 0.242). Two-D camera-based estimation of the pelvic tilt correlated with the 3-D pelvic tilt (r = 0.89-0.94, p < 0.001). In Experiment II, the kick-back score was not significantly different between groups (d = 0.11, p = 0.41). The pelvic tilt was higher in the previously injured than in non-injured players in the late swing phase (d = -0.79, p = 0.03). Our results suggest that the kick-back score is not associated with the pelvic tilt. Nevertheless, the estimation of the pelvic tilt in field settings is feasible through the tracking of two markers on the pelvis in the sagittal plane. Additionally, longitudinal studies are recommended to gain deeper understanding of the excessive pelvic tilt in previously injured female soccer players.

Recently, an elevated rear component of the ski binding has been associated with a reduced ACL injury risk. However, the underlying mechanism is unknown. This study aimed to evaluate the impact of elevated rear components of the ski binding on lower extremity joint angles and the center of mass (COM) in recreational skiers. To evaluate ankle, knee and hip joint angles and the COM, a cohort of 25 subjects (mean age: 25.4 ± 1.8 years) performed unipedal standing trials within a ski boot at four heel heights (position 0: +0.2 cm; position 1: +0.5 cm; position 2: +1.5 cm and position 3: +3.0 cm) on a force plate using an optical motion capture system. Repeated measures ANOVA revealed that flexion angles at the ankle joint significantly differed (η2 = 0.145) and were lowest at position 3, indicating a more neutral ankle joint (-1°). Flexion angles at the knee joint significantly increased with increasing heel height (η2 = 0.715) and were highest at position 3 (+6.9°), indicating a more flexed knee joint. Hip joint angles were not significantly different between the four different conditions (η2 = 0.082). The anterior-posterior COM position differed significantly between the four testing positions (η2 = 0.668) and was most anterior at position 3 (+3.7 cm), indicating a forward movement of the COM. An elevation of the heel component of the ski binding causes an increase in knee flexion accompanied by a forward movement of the COM, both potentially increasing hamstring co-activation as an advantageous preventive measure for ACL injuries in recreational skiing.

Improving the competitive level of elite athletes is always a considerable challenge for coaches, regardless of the sport discipline or a training phase. From this perspective, researchers and sport scientists continuously seek more effective training methods, capable of inducing acute changes or long-term adaptations in athletes with diverse training backgrounds. Recently, priming exercises have emerged as a promising approach to enhance athletic performance over short periods of time, either before sport-specific training sessions or official competitions. By incorporating different priming protocols into their regular practices-including sets of traditional resistance exercises, ballistic exercises or sprint drills-athletes have consistently achieved significant improvements in their speed and power qualities within time intervals ranging from 2 h to 48 h. This narrative review summarizes and examines the main studies on this topic, while providing practitioners with theoretical perspectives, practical insights, and guidelines for implementing efficient priming protocols in their training routines. In conclusion, priming interventions generally produce positive outcomes, irrespective of the exercise type and athletes' backgrounds, and may facilitate the transfer of these benefits to certain sport-specific tasks.

It is a critical tactic in combat sports to launch consecutive attacks that consist of two or more individual kicks strung together in time. The study aimed to assess how the number of round kicks would impact reaction time (RT) and movement time (MT). Twenty-eight experienced taekwondo athletes performed one of four different kick responses randomly in a simple RT paradigm: 1) clenched lead fist without a kick (task A); 2) round kick following task A (task B); 3) double kick following task B (task C); and 4) turning kick following task C (task D). Electromyography recordings from the thenar muscle and acceleration impulses from a triaxial accelerometer positioned at the heavy bag were used to determine premotor time and kick time, respectively. Repeated-measures ANOVA revealed that task B, task C, and task D significantly increased RTs (p < 0.001). The RT of task D was longer than that of task B and task C (p < 0.001). The movement time of the round kick in task C and task D was longer than in task B (p < 0.001). The movement time of the double kick in task D was longer than in task C (p = 0.003). Additional time is required to prepare for multi-kicks responses. An increased number of individual kicks to execute as a whole may slow down the kick movement.

This systematic review aimed to examine the effects of blood flow restriction training (BFRT) on lower extremity muscle strength of athletes. This study followed the PRISMA-P guidelines. A comprehensive search for literature up to August 2024 was conducted on Scopus, Web of Science, PubMed and EBSCOhost to determine the eligible studies based on the inclusion criteria. The Cochrane risk of bias assessment tool was employed to evaluate the methodological quality of studies, the certainty of the evidence was assessed utilizing the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE), and the subgroup analyses were conducted based on moderator factors. A total of sixteen studies with 366 healthy athletes aged 15-27 years were included in the meta-analyses. The results indicated a moderate to large effect size (ES) of BFRT on the isokinetic knee flexion peak torque (ES = 0.88; p < 0.05), lower extremity dynamic strength-1RM (ES = 0.99; p < 0.001), and isokinetic knee extension peak torque (ES = 1.47; p < 0.001). The findings of subgroup analysis revealed that BFR-RT training (ES = 1.20-1.95; p < 0.05), training frequency of ≥ 3 times per week (ES = 1.13-1.16; p < 0.001), occlusion pressures of ≥ 160 mmHg (ES = 1.32-2.23; p < 0.01) and cuff width of > 7 cm (ES = 1.84-11.84; p < 0.01) were more beneficial to isokinetic muscle strength. No significant difference was observed in training duration (p > 0.05). In conclusion, blood flow restriction training is effective in enhancing lower extremity muscle strength in healthy athletes.

Intermittent palm cooling (PC) could benefit strength performance. However, its effect on baseball throwing, which requires explosive strength, has yet to be determined. This study aimed to examine whether intermittent PC would enhance repeated baseball throwing performance and how pain after PC would affect outcomes. Twenty-two university division II male baseball athletes were instructed to perform five sets of 10 throws at maximum speed toward a target, separated by 3-min of recovery with PC into 10°C water or non-cooling (NC). Participants were classified into the no-pain group (NPG, n = 10) and mild-to-moderate pain group (PG, n = 12) according to their pain sensation after PC for data analysis. The results showed a significantly lower rating of perceived exertion under PC conditions (p < 0.05). In the NPG, PC resulted in higher mean throw velocity (107.9 ± 9.9 vs. 106.9 ± 10.2 km/h), maximal throw velocity (112.5 ± 9.0 vs. 111.2 ± 9.8 km/h), accuracy, and the arousal level than NC; in the PG, PC resulted in lower mean throw velocity (101.0 ± 11.1 vs. 105.2 ± 10.5 km/h) and maximal throw velocity (105.0 ± 10.8 vs. 108.7 ± 9.8 km/h) when compared with NC (p < 0.05). However, no significant difference was noted in accuracy and arousal levels between PC and NC (p > 0.05) in the PG. In conclusion, after PC, pain-free baseball athletes can enhance their baseball throwing performance. The presence or absence of pain after PC can serve as an initial assessment of whether to use it as an ergogenic aid strategy.

Jump monitoring has become an essential procedure for training load management and injury prevention in many sports, such as beach volleyball. This study aimed to assess the validity of WIMU PRO^TM devices for jump detection in beach volleyball and to determine, in a preliminary way, whether gender, the player's individuality or the technical action associated with the jump could influence data accuracy. Eleven beach volleyball players (6 female and 5 male) were recorded with high-definition cameras and the WIMU PRO^TM device during 42 one-set official matches. The number of jumps recorded by the device was compared with the observational analysis. The instrument's sensitivity was calculated based on true positives and false positives/negatives in terms of gender, player individuality, and the type of the jump. The WIMU PRO^TM device presented great sensitivity (96.29%), with a lower gender difference (male = 97.20%, female = 94.56%) and higher inter-player variability in females (91.06%-98.08%) than males (95.02%-98.40%). Regarding the type of the jump, actions classified as "Others" (99.10 %) obtained the greatest sensitivity, followed by "Block" (97.25 %), "Spike" (95.75 %) and "Serve" (94.69 %). The WIMU PRO^TM is a valid device for automatic jump detection in beach volleyball. The variations observed in terms of gender, players' individuality, and the type of the jump highlight the importance of a context-specific individualized algorithm adjustment.

This study aimed to compare the effects of scapular stability training (SST) alone and combined scapular stability and thoracic flexibility training (TFT) in elite table tennis players with scapular dyskinesis (SD). Thirty players were categorized into three groups based on the presence of scapular dysfunction: the control (n = 10), shoulder (n = 10, with dysfunction), and chest groups (n = 10, with dysfunction). The shoulder group underwent scapular stability training alone, while the chest group underwent combined scapular stability and thoracic flexibility training. Various variables, including average track error (ATE), angular velocity, lateral scapular slide test (LSST) positions, upper quarter Y-balance test (YBT) distance, and range of motion (ROM) of thoracic rotation, were measured before and after the interventions. For the shoulder group, the playing-side ATE decreased significantly after the experiment (p = 0.005), along with increased angular velocity. LSST positions one, two, and three were smaller after the experiment (p values of 0.008, 0.008, and 0.009, respectively), indicating improved proprioception. The chest group exhibited significant differences in playing-side ATE, angular velocity, LSST positions two and three, YBT distance, and ROM thoracic rotation after training (all p < 0.05). The playing-side YBT distance (p = 0.002), ROM of thoracic rotation to the right (p = 0.001), and angular velocity (p = 0.003) were all higher in the chest group than in the shoulder group. Both interventions positively impacted scapular stability, but combined training, especially in the chest group, showed additional benefits in terms of angular velocity, YBT distance and thoracic rotation. These findings suggest that combined scapular stability and thoracic flexibility training may offer superior outcomes in elite table tennis players with SD.

This study explores the relationship between Career Indicators (CIs) and the retiring age of Portuguese soccer players, focusing on the impact of early career experiences and career discontinuation stages. Data were analyzed from retired Portuguese soccer players registered on a private digital platform, using specific CIs related to different stages of their athletic careers. The analysis involved a two-level mediation model incorporating various CIs. Significant direct effects emerged with 'the number of seasons as a youth player' and 'the number of seasons as a youth player in top 3 clubs' on 'retiring age'. Additionally, a strong association was identified between 'discontinuation stage length' and 'retiring age'. The findings emphasize the importance of effectively managing career discontinuation stages and proactive career planning. Consequently, comprehensive support programs offering resources and guidance for career transitions are recommended for soccer players. The study underlines the key role of stakeholders in enabling smoother transitions into retirement.