Journal of Sports Medicine and Physical Fitness最新文献

Background: During the basketball season, it is essential to carefully plan training and recovery activities to optimize players' performance. This study monitored training load and perceived recovery indicators in professional female basketball players across the preseason and in-season phases.

Methods: Seventeen professional female basketball players (age: 19.6±3.1 years; height: 180.2±5.9 cm; playing position: 8 backcourt, 9 frontcourt) were monitored for eleven consecutive weeks. Each morning, players reported their perceived recovery using a 10-point Total Quality of Recovery (TQR) Scale. After each training session or game, players reported their perceived exertion using the CR-10 Scale, which was multiplied by the duration of the training or game to obtain the session load. Weekly load, monotony, strain, TQRAM (morning recovery) and TQRfw (recovery at the start of the following week) were calculated. Linear mixed models were performed to assess the effects of season phase (preseason; in-season), playing position (backcourt; frontcourt) and group (senior; under) on load and recovery variables.

Results: Weekly load, monotony and strain were higher in the preseason than the in-season phase (all P<0.001, ES: moderate-large). Strain was higher in senior players compared to under (P=0.045, ES: small). Regarding recovery variables, no effects were found for TQRAM, while TQRfw was higher in the preseason than in-season (P<0.001, ES: moderate) phase.

Conclusions: Professional female basketball players experience lower internal loads but poorer perceived recovery during the in-season phase. Practitioners should carefully consider the stress of competition and the cumulative fatigue from high preseason loads during the transition from the preseason to the regular season.

Background: Soccer involves many physically challenging actions and engaging in such activities can induce a decline in performance due to physical fatigue which predisposes players to develop injuries. The present study aimed to examine the impact of post-match fatigue on functional performance and Inter-Limb Asymmetry Index (LSI) in adolescent soccer players.

Methods: Thirty-eight adolescent male soccer players (15-18 years) completed a battery of functional performance measures (Rate of Perceived Exertion (RPE) scale, 10 m sprint, agility T-test, and Single leg hop for distance (SLHD) test). The data collection started prior to a soccer match and consisted of two testing sessions; two hours before the match, while the subsequent testing session was performed within two hours immediately following the match.

Results: The study results revealed a significant effect of post-match fatigue on change of direction abilities and SLHD (moderate effect size). However, no significant differences were observed in the 10 m sprint test and LSI (P>0.05).

Conclusions: Functional performance measures such as agility test and SLHD test can detect physical ability changes due to post-match fatigue in adolescent soccer players. The study findings offer insightful and practical information on the importance of employing field-based functional performance measures in monitoring players' recovery following a game.

Background: Blood flow restriction (BFR) has been shown to enhance the effectiveness of low load resistance exercise, but less research has examined its utility in conjunction with maximal isokinetic contractions, which may depend on the restrictive pressure and speed of contraction.

Methods: Individuals reported to the laboratory for three visits to complete three sets of 20 maximal elbow flexion exercises at 60°/s and 300°/s under 0%, 40% and 80% of their arterial occlusion pressure. Muscle thickness was measured before and after exercise, and ratings of discomfort, perceived activation, and exercise-induced feelings were obtained at the completion of each exercise. Fatigue was assessed as the decline in average peak torque across the three sets.

Results: A total of 27 individuals (11 females, 16 males) completed the study. There was a significant interaction for torque at both 60°/s and 300°/s (P<0.001), with each increasing pressure resulting in greater fatigue. Muscle swelling was present across all conditions but was lowest in the 40% BFR condition applied during the 300°/s speed. At both 60°/s and 300°/s speeds, the 80% BFR pressure was associated with lower enjoyment, greater discomfort, and greater perceived activation (all P<0.05).

Conclusions: The combined effects of BFR to maximal isokinetic contractions increased fatigue with less of an impact on muscle swelling. These results indicate that BFR may enhance the effectiveness of long-term isokinetic training, but it is also important to consider the addition of BFR was associated with lower levels of enjoyment and greater discomfort which may decrease adherence.

Background: The analysis of athletic performance has always aroused great interest from sport scientist. This study utilized machine learning methods to build predictive models using a comprehensive CrossFit (CF) dataset, aiming to reveal valuable insights into the factors influencing performance and emerging trends.

Methods: Random forest (RF) and multiple linear regression (MLR) were employed to predict performance in four key weightlifting exercises within CF: clean and jerk, snatch, back squat, and deadlift. Performance was evaluated using R-squared (R²) values and mean squared error (MSE). Feature importance analysis was conducted using RF, XGBoost, and AdaBoost models.

Results: The RF model excelled in deadlift performance prediction (R²=0.80), while the MLR model demonstrated remarkable accuracy in clean and jerk (R²=0.93). Across exercises, clean and jerk consistently emerged as a crucial predictor. The feature importance analysis revealed intricate relationships among exercises, with gender significantly impacting deadlift performance.

Conclusions: This research advances our understanding of performance prediction in CF through machine learning techniques. It provides actionable insights for practitioners, optimize performance, and demonstrates the potential for future advancements in data-driven sports analytics.

Background: Interventions on ankle motor control are important to prevent recurrent ankle sprains. Training using whole-body vibration may easily and effectively improve ankle motor control, but the effects have not been investigated. Therefore, this study aimed to clarify the effects of 6 weeks of training with whole-body vibration on ankle motor control in a dynamic movement task among healthy participants.

Methods: Twenty healthy university students (6 males and 14 females) were randomly allocated to whole-body vibration training and control groups, with 10 participants in each group. The training was performed twice a week for 6 weeks in both groups. Primary outcome was mean ankle angular jerk cost in the star excursion balance test. Secondary outcomes were maximum ankle motion angle and maximum reach distance in the star excursion balance test, ankle proprioception, and range of ankle dorsiflexion motion in the loaded position.

Results: There was a significant group × period (pre- and postintervention) interaction for mean ankle angular jerk cost in the direction of ankle abduction/adduction during posterolateral reaching, which was significantly lower at postintervention than that at preintervention in the whole-body vibration group In the whole-body vibration group, the maximum ankle dorsiflexion motion angle during anterior and posterolateral reaching was significantly higher at postintervention than that at preintervention.

Conclusions: Training with whole-body vibration improves ankle motor control in dynamic movement tasks, although the direction of reach and plane of motion are limited. Additionally, training with whole-body vibration is also effective in increasing the ankle dorsiflexion angle during dynamic movement tasks.

Background: In baseball pitches, the forkball requires a special grip, pinching the ball between the second and third fingers to achieve the resulting breaking ball trajectory. We hypothesized that the forkball grip would have a substantial impact on the hardness of the flexor digitorum superficialis. The aim was to quantify and clarify the change in the hardness of the flexor digitorum superficialis due to the forkball grip.

Methods: Twenty-one adult male subjects were recruited and instructed to perform two baseball grips with the ball: fast and forkball, and the rest without the ball. The shear wave speeds of the pronator teres, flexor carpi radialis, flexor digitorum superficialis, and flexor carpi ulnaris were measured using shear wave elastography.

Results: In the forkball grip, compared with the fastball grip and the rest without the ball, the shear wave speed of the flexor digitorum superficialis was significantly higher than those of the pronator teres, flexor carpi radialis, and flexor carpi ulnaris (P<0.001), indicating that muscle hardness increased due to the forkball grip. In contrast, no significant differences were found between the conditions for the other forearm flexor-pronator muscles.

Conclusions: Quantification of muscle hardness using shear wave elastography showed that gripping a forked ball increased muscle hardness in the flexor digitorum superficialis.

Background: In javelin, although many previous studies have examined throwing movements that can increase initial velocity, the characteristics of throwing arm movement an elongated implement have not been clarified. The purpose of the present study was to examine the characteristics of the throwing movement of an elongated implement by comparing throwing movement between a javelin and baseball.

Methods: Twelve male javelin throwers were asked to perform a javelin throw (JT) and a baseball long toss (LT) twice. The three-dimensional coordinates of reflective markers attached to the athlete's body, javelin, and baseball were measured using an optical motion capture system. %Trajectory was used as an index to evaluate the degree to which the hand was moved linearly during the throw. A smaller value of this indicator meant that the hand was move closer to a straight line. The joint angles in the throwing arm were obtained by calculating the Euler angles between body segments. These data were used to compare JT and LT.

Results: %Trajectory showed that JT was significantly smaller than LT. Significant differences in the joint angles of the throwing arm were noted between JT and LT.

Conclusions: JT showed a kinematic pattern in which the hand was moved more linearly than in baseball long toss.

Background: The development of moral competence seems to be an important factor in the context of youth development. The problem with lack of moral competence among youth has often been observed. Physical education (PE) as a subject in school seems to provide space in the curriculum where moral development can and should be experienced and practiced.

Methods: The participants were high school students (N.=235), divided into 4 groups: two experimental and two control groups. The difference between the experimental groups was the frequency of the experiment. The first group carried out two units a week for one semester, and the second group one lesson unit throughout the school year. As a research tool the Moral Competence Test was used.

Results: The results indicate statistically significant positive changes between the score of Community Index (C-Index) in pretest and post-test for both experimental group (P<0.05; η²=0.04), and between pretest and follow-up in second experimental group (P<0.05; η²=0.05). Whereas in the control groups, there were no significant changes in the comparison of terms (pretest, post-test, follow-up) (P>0.05).

Conclusions: Based on the study, it can be determined that the curriculum of physical education, based on the model of non-linear pedagogy, can increase the level of moral competence among young people.

Background: Ratings of perceived exertion (RPE) can be used to regulate exercise intensity. This study examined the effect of anchor scheme on performance fatigability and neuromuscular responses following fatiguing forearm flexion tasks.

Methods: Twelve men (age 20.9±2.2 years; height 179.8±5.3 cm; body mass 80.2±9.9 kg) performed sustained, isometric forearm flexion tasks to failure anchored to RPE=6 (RPEFT) and the torque (TRQFT) that corresponded to RPE=6. Pre-test and post-test maximal voluntary isometric contractions (MVIC) were performed to quantify changes in the amplitude (AMP) and mean power frequency (MPF) of the electromyographic (EMG) and mechanomyographic (MMG) signals. Neuromuscular efficiency (NME) was calculated by dividing normalized torque by normalized EMG AMP. A dependent t-test was used to assess the mean difference for time to task failure (TTF). Repeated measures ANOVAs were used to compare mean differences for performance fatigability and normalized neuromuscular parameters.

Results: The RPEFT had a greater TTF than the TRQFT (P<0.001). MVIC and NME decreased from pre-test to post-test following the RPEFT and TRQFT (P<0.05) with no differences between anchor schemes. Following the TRQFT, normalized EMG MPF decreased from pre-test to post-test (P=0.004). Following the RPEFT, normalized MMG MPF increased from pre-test to post-test (P=0.021). There were no changes in normalized EMG AMP or MMG AMP (P>0.05).

Conclusions: These findings indicated anchor scheme-specific neuromuscular responses and TTF, despite no difference in performance fatigability. Furthermore, performance fatigability was likely due to peripheral fatigue (based on normalized EMG MPF and NME) following the TRQFT, but peripheral and central fatigue (based on normalized MMG MPF and NME) following the RPEFT.

Introduction: Various tests have been developed to evaluate aerobic fitness and performance of runners. However, a systematic understanding of which methods are more accurate is necessary to provide coaches and the sports sciences community with useful and confident outcomes. This study aims to summarize the evidence regarding the validity, reliability and sensitivity of tests for measuring aerobic fitness and performance in runners of several background of training.

Evidence acquisition: A systematic search was conducted of Web of Science, PubMed and Scopus up to 31^st December 2022 according to PRISMA statement guidelines. Studies that reported findings about tests covering maximal aerobic speed, final velocity achieved during the test, average running speed or other method of evaluating the reference speed during the test were included. We evaluated the risk of bias in the included articles using the Risk of Bias Assessment Tool for Nonrandomized Studies (RoBANS). The tests were categorized into continuous incremental tests, intermittent tests and time-trial test.

Evidence synthesis: A total of 23 studies met eligibility criteria. These studies contained three background of training: track and road runners (N.=15), trail runners (N.=7) and inexperienced runners (N.=1). Criterion validity was assessed in 73% of the studies, while only 41% of studies examined convergent validity. The majority of the reviewed studies (87%) ignored test-retest reliability. Test sensitivity was not reported in any study.

Conclusions: At least one aerobic fitness and performance test was identified for each types of background of training. However, some methodological aspects were not provided in the included articles. Most studies examined at least one aspect of validity (i.e., criterion or convergent-related validity), whilst few studies investigated test-retest reliability. Researchers and practitioners can use the information provided in this systematic review to select appropriate tests.