Journal of Sports Science and Medicine最新文献

Repeated-sprint training in hypoxia (RSH) has been shown to boost team-sport players' repeated-sprint ability (RSA). Whether players' global inspiratory muscle (IM) and core muscle (CM) functions would be altered concomitantly with RSH was not reported. This study was designed to compare the concomitant alternations in players' RSA and their IM and CM functions during a team-sport-specific intermittent exercise protocol (IEP) before and after the intervention. Twenty players were assigned into either RSH or control (CON) groups (n = 10 for each). RSH players participated in 5-wk RSH (15 sessions, 3 sets 5x5-s all-out treadmill sprints interspersed with 25-s passive recovery under the hypoxia of 13.5%) while CON players had no corresponding training. The changes in RSA between pre- and post-intervention, and the alterations in IM and CM functions that were revealed by maximum inspiratory mouth pressure (PI_max) and sport-specific endurance plank test (SEPT) performance, respectively, between pre- and post-IEP and across pre- and post-intervention in the RSH group were compared with that of CON. Following the 5-wk RSH, players' RSA improved significantly (>6%, p < 0.05) while PI_max and SEPT performance did not alter (P > 0.05). Nevertheless, PI_max which declined markedly in pre-intervention IEP (pre-IEP 155.4 ± 22.7 vs post-IEP 140.6 ± 22.8 cmH₂O, p < 0.05) was alleviated significantly in post-intervention IEP (152.2 ± 27.4 vs 152.6 ± 31.8, p > 0.05), while the concomitant declined SEPT performance in the pre-intervention IEP (155 ± 24.6 vs 98.1 ± 21.7 s, p < 0.05) was retained post intervention (170.7 ± 38.1 vs 100.5 ± 33.4, p < 0.05). For the CON, all variables were unchanged (p > 0.05). Such findings suggest that 5-wk RSH could enhance players' RSA but not global IM and CM functions. Nonetheless, the decline in PI_max in pre-intervention IEP alleviated significantly post intervention led to a postulation that players' IM endurance, rather than strength, might improve with the 5-wk RSH regimen, while the possible improved IM endurance did not advance the fatigue resistance of CM.

Repeated sprint ability (RSA) is crucial for success in team sports, and involves both neuromuscular and metabolic factors. While single-mode training (SGL; e.g., sprint training) and combined training (CT; e.g., sprint + plyometric) can improve RSA, whether CT offers additional benefits compared to SGL or active controls maintaining routine training (CON) remains uncertain in team-sport athletes. This study evaluates the effect of CT versus SGL and CON on the RSA of team-sport athletes. A comprehensive search was conducted in five electronic databases. Thirteen studies involving 394 males and 28 females, aged 14 to 26 years, were included. The random effects model for meta-analyses revealed greater improvement in RSA mean after CT compared to SGL (Hedge's g effect size [g] = -0.46; 95 % confidence interval [CI]: -0.82, -0.10; p < 0.01) and CON (g = -1.39; 95% CI: -2.09, -0.70; p < 0.01). CT also improved RSA best compared to CON (g = -1.17; 95% CI: -1.58, -0.76; p < 0.01). The GRADE analyses revealed low- to very-low certainty of evidence in all meta-analyses. Subgroup analysis revealed that plyometric + sprint training yielded greater RSA mean (g = -1.46) and RSA best (g = -1.35) improvement than plyometric + resistance + sprint training and resistance + sprint training. The effects of CT on RSA did not differ according to age (≥ 18 vs. < 18), sports (e.g., soccer vs. basketball vs. handball), or RSA test type (linear sprint vs. sprint with change-of-direction). Studies showed an overall high risk of bias (ROB 2). In conclusion, CT may be improving team-sport athletes' RSA more effectively than SGL (small effect size) and CON (large effect size), particularly when CT involves plyometric + sprint training.

Tissue flossing involves wrapping a rubber band around a muscle group for a few minutes while performing joint motion, enhancing ankle joint torque and range of motion. As limited ankle dorsiflexion range of motion and plantar flexion muscle weakness are risk factors for sports injury, assessing the therapeutic effects of tissue flossing is important. This study aimed to evaluate the immediate effects of calf tissue flossing on enhancing ankle joint torque and dorsiflexion range of motion. We conducted a randomized controlled crossover trial involving 19 healthy adult males who received two interventions (low and high-pressure tissue flossing bands) and a control condition (underwrap). Each intervention was applied for 2 minutes on the non-dominant calf, with 5-10 days between sessions. A pressure sensor placed on the posterior calf monitored the wrapping compression force. The intervention exercise comprised six voluntary isometric contractions of the ankle at three angles (20° plantar flexion, neutral 0°, and 10° dorsiflexion) for 3 seconds each using a dynamometer. The maximal isometric ankle plantar flexion torque and dorsiflexion range of motion were evaluated pre- and post-intervention. Significant interactions were observed in ankle plantar flexion torque at 10° dorsiflexion (p < 0.01) but not at 0° or 20° plantar flexion. The low- and high-pressure bands significantly enhanced ankle plantar flexion torque by 4.3 Nm (effect size [ES]: 0.14, p = 0.02) and 4.9 Nm (ES: 0.15, p < 0.05), respectively, and also enhanced the ankle dorsiflexion range of motion by 1.7° (ES: 0.43, p < 0.01) and 1.3° (ES: 0.35, p = 0.02), respectively, compared to the control. The low- and high-pressure band conditions had comparable effects on torque and range of motion. A few minutes of the calf tissue flossing intervention significantly enhanced ankle plantar flexion torque and dorsiflexion range of motion, although the effect sizes were trivial to small.

The purpose of this study was to compare the adaptations in muscular strength, power, and landing forces of young female volleyball players enrolled in two experimental programs: one using smaller formats of the game (SFG) and the other using larger formats of the game (LFG), with a third group serving as a control. This study employed a randomized controlled design, with an 8-week intervention period and pre- and post-intervention evaluations. Fifty-six trained/developmental participants (age: 14.7 ± 0.5 years) voluntarily participated in this study. Each experimental group received additional training twice a week. The SFG group participated in 2v2 and 3v3 formats on smaller courts (covering 2/6 of the court's available zones) with a regular net, while the LFG group played in 4v4 and 5v5 formats on larger courts (covering 4/6 of the court's available zones). Assessments were conducted using force platforms and included the following tests: (i) isometric mid-thigh pull test (IMTP), measuring peak force; (ii) squat jump test (SJ), measuring peak force; (iii) countermovement jump test (CMJ), measuring peak power and landing force; and (iv) drop jump test (DJT), measuring the reactive strength index. Significant differences emerged post-intervention across all outcomes (p < 0.05). The SFG exhibited significantly greater IMTP peak force compared to both the LFG (p = 0.012) and control groups (p = 0.035). Additionally, the SFG showed significantly greater SJ peak force than the LFG (p = 0.036) and control groups (p = 0.023). Regarding CMJ peak power, significantly higher values were observed in the SFG compared to the LFG (p = 0.042) and control groups (p = 0.046). Moreover, the SFG had significantly lower CMJ peak landing force than both the LFG (p = 0.049) and control groups (p = 0.046). Finally, RSI was significantly higher in the SFG than in the LFG (p = 0.046) and control groups (p = 0.036). This study highlights the significant benefits of incorporating 2v2 and 3v3 SFG formats to enhance muscular strength, power, and landing forces in young female volleyball players, contrasting with less effective outcomes observed with 4v4 and 5v5 LFG formats, suggesting potential neuromuscular advantages crucial for improving volleyball performance.

Motor imagery (MI) or post-activation performance enhancement (PAPE) have shown acute benefits for sports performance. The aim of the present study was to investigate the cumulative effects of MI and PAPE when combined within a warm-up routine. Ten men boxers participated in this study. They underwent four experimental sessions composed of a standardized warm-up followed by 1) maximal leg press extensions (CONTROL-PAPE), 2) mental imagery of force and sprint tasks (CONTROL-MI), 3) maximal leg press extensions followed by mental imagery of force and sprint tasks (PAPE-MI) and 4) mental imagery of force and sprint tasks followed by then maximal leg press extensions (MI-PAPE). Post-tests consisted of boxing reaction time, average and maximal boxing force, maximal handgrip strength, repeated sprint ability and the NASA-TLX fatigue questionnaire. No difference was obtained between PAPE-MI and MI-PAPE for the different measurements. Compared to CONTROL-PAPE and CONTROL-MI, both the PAPE-MI and MI-PAPE significantly enhanced boxing average force (P < 0.05) and repeated sprint ability (P < 0.01). Compared to CONTROL-PAPE, both the PAPE-MI and MI-PAPE increased boxing reaction time (P < 0.05), PAPE-MI increased the handgrip strength (P < 0.05) and MI-PAPE increased boxing maximal force (P < 0.01). Compared to CONTROL-MI, both the PAPE-MI and MI-PAPE increased boxing maximal force (P < 0.001), handgrip strength (0 < 0.01) and MI-PAPE increased boxing reaction time (P < 0.05). The NASA-TLX questionnaire was not affected by the warm-up modalities (P = 0.442). Combining PAPE-MI and MI-PAPE protocols within the warm-up produced cumulative positive effects on acute muscular performance without increasing subjective fatigue. PAPE-MI and MI-PAPE are both interesting modalities for optimizing warm-up routines.

Osgood-Schlatter disease (OSD) is caused by high, repetitive, and continuous traction exerted by the quadriceps on the tibial tuberosity, primarily occurring in adolescents. Infrapatellar straps are commonly recommended for its prevention and treatment, yet their impact on quadriceps forces in adolescents remains unstudied. Furthermore, current research on OSD predominantly focuses on adolescent males, with limited attention to adolescent females, despite similar incidence rates in both groups. This study aimed to quantify the quadriceps forces during running, both with and without infrapatellar straps, in adolescent females. Kinematic data, ground reaction forces, and electromyography (EMG) data of knee muscles from 16 adolescent females were recorded as they ran at self-selected speeds with and without infrapatellar straps. OpenSim was employed to estimate quadriceps activations and forces, from which accumulated forces were derived. The simulation's reliability was validated by calculating the correlation between muscle activations obtained from OpenSim and EMG data, which revealed a strong correlation. Wearing infrapatellar straps during running decreased the peak and accumulated forces of the quadriceps (p < 0.001, and p < 0.001, respectively). The significant reduction in accumulated forces was associated with decreased vastus muscle forces during the stance phase (p = 0.002, p = 0.003, and p = 0.016 for vastus lateralis, vastus medialis, and vastus intermedius, respectively). The use of infrapatellar straps had limited effect on the rectus femoris muscle forces. The reliability of the simulation was validated through EMG data. Wearing infrapatellar straps may reduce the load exerted on the tibial tuberosity by decreasing vastus muscle forces during the stance phase. Adolescents aiming to reduce excessive rectus femoris muscle forces due to a shortened or tight rectus femoris, which may contribute to the occurrence of OSD, might experience limited benefits from wearing infrapatellar straps.

Interventions involving exposure to nature can increase self-regulatory resources. However, this improvement has never been examined in mentally fatigued soccer players who have insufficient resources to self-regulate and maintain specific performances. The present study aims to investigate how exposure to nature influences the self-regulation capability of university soccer players who are mentally fatigued. The participants aged 18-24 years (M = 20.73 ± 2.00), with an average training duration of 5.14 ± 1.31 years, were randomly divided into six different groups (three experimental groups and three control groups). Each experimental group was compared with its corresponding control group using three different intervention durations: 4.17 min, 8.33 min, and 12.50 min. A forty-five-minute Stroop task was used to induce mental fatigue, followed by the intervention. The indicators of self-regulation, both physiological (heart rate variability, or HRV) and psychological (competitive state anxiety), were recorded. Experimental Group 3 (12.50 min intervention) only showed significant improvement in HRV (p = 0.008, d = 0.93), competitive state anxiety (cognitive and somatic anxiety p = 0.019, d = 0.86; state confidence p = 0.041, d = 0.797) compared to control group 3. Nature exposure significantly improves self-regulation in mentally fatigued soccer players. Specifically, the 12.50 min intervention showed the greatest improvements in both HRV and competitive state anxiety, suggesting that a longer duration of nature exposure enhances mental restoration more effectively.

This study aimed to identify relationships between external and internal load parameters with subjective ratings of perceived exertion (RPE). Consecutively, these relationships shall be used to evaluate different machine learning models and design a deep learning architecture to predict RPE in highly trained/national level soccer players. From a dataset comprising 5402 training sessions and 732 match observations, we gathered data on 174 distinct parameters, encompassing heart rate, GPS, accelerometer data and RPE (Borg's 0-10 scale) of 26 professional male professional soccer players. Nine machine learning algorithms and one deep learning architecture was employed. Rigorous preprocessing protocols were employed to ensure dataset equilibrium and minimize bias. The efficacy and generalizability of these models were evaluated through a systematic 5-fold cross-validation approach. The deep learning model exhibited highest predictive power for RPE (Mean Absolute Error: 1.08 ± 0.07). Tree-based machine learning models demonstrated high-quality predictions (Mean Absolute Error: 1.15 ± 0.03) and a higher robustness against outliers. The strongest contribution to reducing the uncertainty of RPE with the tree-based machine learning models was maximal heart rate (determining 1.81% of RPE), followed by maximal acceleration (determining 1.48%) and total distance covered in speed zone 10-13 km/h (determining 1.44%). A multitude of external and internal parameters rather than a single variable are relevant for RPE prediction in highly trained/national level soccer players, with maximum heart rate having the strongest influence on RPE. The ExtraTree Machine Learning model exhibits the lowest error rates for RPE predictions, demonstrates applicability to players not specifically considered in this investigation, and can be run on nearly any modern computer platform.

Ischemic preconditioning (IPC) is a strategy that may enhances endurance performance in thermoneutral environments. Exercising in the heat increases thermoregulatory and cardiovascular strain, decreasing endurance performance. The current study aimed to determine whether IPC administration improves endurance performance in the heat. In a randomized crossover design, 12 healthy subjects (V̇O_2max: 54.4 ± 8.1 mL·kg^-1·min^-1) underwent either IPC administration (220 mmHg) or a sham treatment (20 mmHg), then completed a moderate-intensity 6-min running (EX1) and a high-intensity time-to-exhaustion running test (EX2) in a hot environment (35 °C, 50 % RH). Cardiac function, oxygen consumption (V̇O₂), and core body temperature (T_CORE) were measured. During EX2, IPC administration increased the total running time in the heat compared to the sham treatment (IPC: 416.4 ± 61.9 vs. sham 389.3 ± 40.7 s, P = 0.027). IPC administration also increased stroke volume (IPC: 150.4 ± 17.5 vs. sham: 128.2 ± 11.6 ml, P = 0.008) and cardiac output (IPC: 27.4 ± 1.7 vs. sham: 25.1 ± 2.2 ml min^-1, P = 0.007) during 100% isotime of EX2. End-exercise V̇O₂ (IPC: 3.72 ± 0.85 vs. sham: 3.54 ± 0.87 L·min^-1, P = 0.017) and slow phase amplitude (IPC: 0.57 ± 0.17 vs. sham: 0.72 ± 0.22 L·min^-1, P = 0.016) were improved. When compared with the baseline period, an increase in T_CORE was less in the IPC condition during EX1 (IPC: 0.18 ± 0.06 vs. sham: 0.22 ± 0.08 °C, P = 0.005) and EX2 (IPC: 0.87 ± 0.10 vs. sham: 1.03 ± 0.10 °C, P < 0.001). IPC improves high-intensity endurance performance in the heat by 6.9 %. This performance benefit could be associated with improved cardiac and thermoregulatory function engendered by IPC administration.

OpenPose-based motion analysis (OpenPose-MA), utilizing deep learning methods, has emerged as a compelling technique for estimating human motion. It addresses the drawbacks associated with conventional three-dimensional motion analysis (3D-MA) and human visual detection-based motion analysis (Human-MA), including costly equipment, time-consuming analysis, and restricted experimental settings. This study aims to assess the precision of OpenPose-MA in comparison to Human-MA, using 3D-MA as the reference standard. The study involved a cohort of 21 young and healthy adults. OpenPose-MA employed the OpenPose algorithm, a deep learning-based open-source two-dimensional (2D) pose estimation method. Human-MA was conducted by a skilled physiotherapist. The knee valgus angle during a drop vertical jump task was computed by OpenPose-MA and Human-MA using the same frontal-plane video image, with 3D-MA serving as the reference standard. Various metrics were utilized to assess the reproducibility, accuracy and similarity of the knee valgus angle between the different methods, including the intraclass correlation coefficient (ICC) (1, 3), mean absolute error (MAE), coefficient of multiple correlation (CMC) for waveform pattern similarity, and Pearson's correlation coefficients (OpenPose-MA vs. 3D-MA, Human-MA vs. 3D-MA). Unpaired t-tests were conducted to compare MAEs and CMCs between OpenPose-MA and Human-MA. The ICCs (1,3) for OpenPose-MA, Human-MA, and 3D-MA demonstrated excellent reproducibility in the DVJ trial. No significant difference between OpenPose-MA and Human-MA was observed in terms of the MAEs (OpenPose: 2.4° [95%CI: 1.9-3.0°], Human: 3.2° [95%CI: 2.1-4.4°]) or CMCs (OpenPose: 0.83 [range: 0.99-0.53], Human: 0.87 [range: 0.24-0.98]) of knee valgus angles. The Pearson's correlation coefficients of OpenPose-MA and Human-MA relative to that of 3D-MA were 0.97 and 0.98, respectively. This study demonstrated that OpenPose-MA achieved satisfactory reproducibility, accuracy and exhibited waveform similarity comparable to 3D-MA, similar to Human-MA. Both OpenPose-MA and Human-MA showed a strong correlation with 3D-MA in terms of knee valgus angle excursion.