Journal of Human Kinetics最新文献

Children tend to enjoy high-intensity activities that involve both linear speed (LS) and change of direction (COD), essential for sports performance. However, the results of trends in LS and COD have not been consistent over time. Therefore, our study aimed to investigate the temporal trends in LS and COD performance among 11-13 year old Italian children/preadolescents over 25 years, while minimizing the effect of anthropometric characteristics. A total of 3884 students were recruited between 1990 and 2010 and performed 4 x 5-m shuttle run, 30-m sprint, and 60-m speed tests. A weighted linear regression was performed to analyze the overall temporal trends in BMI-adjusted speed tests. The results showed an increase in mean 4 x 5-m shuttle run time, indicating a decrease in COD ability, while LS performance remained relatively stable over time. These trends were consistent across genders and ages. Our study concludes that LS test performance remained steady over decades, while COD ability declined with sex-based variations despite participants' early age. Our results offer crucial data for interventions to improve children's physical fitness: in particular for COD performance. PE teachers and coaches should prioritize improving COD over LS to improve these abilities and prevent physical fitness decline.

The role of power performance in elite athletes has been enriched by identifying associations between specific single nucleotide polymorphisms (SNPs) and power performance. To deepen our understanding of this association, the objective of this study was to explore the relationship between the genotype and the phenotype in elite athletes. A total of 278 German national squad athletes (156 males, 122 females) underwent genotyping, and their performance in a countermovement jump test (CMJ) and 10-m sprint was assessed. Genotype distribution was analyzed using Chi-square tests. Spearman correlation was employed to examine associations between selected SNPs (e.g., ACTN3, AGT, HSD17B14, IP6K3, MTRR, UCP2, and VDR) and CMJ and sprint performances. Gender-specific polygenic "Total Genotype Scores" (TGSsig) were calculated. Predictive power of TGSsig on power performance was evaluated using linear regression. TGSsig explained 10% of variance in CMJ and sprint performance in both genders. Among males, correlations were identified between AGT and VDR with the CMJ as well as between IP6K3 and sprint performance (p < 0.05). In females, ACTN3, AGT, and UCP2 exhibited associations with the CMJ, while HSD17B14, MTRR, and UCP2 were correlated with sprint performance (p < 0.05). Significant differences in genotype distribution between genders were observed for DMD and MPRIP. Our findings strengthen the idea of power being partly heritable, however, the genotype only partially, by 10%, determines power performance. The role of the athletes' genotype for individual performance development should be investigated in future longitudinal studies.

This study aimed to (1) quantify national-level female soccer players' accumulated microcycle (weekly) training load (accumulated absolute value) and intensity (value relative to duration), (2) investigate possible differences in training load and intensity between teams in the league's top- and bottom-half. Sixty-three females from six teams in the highest league participated in the study. Participants were divided into top-half (TH, n = 28) and bottom-half (BH, n = 35) groups based on their team's league ranking. Players' external and internal training load and intensity were monitored in all on-field training sessions and league matches during a three-week observation period (690 data samples) using the Polar Team Pro system. There were no differences between groups in the number of weekly training sessions or total duration. Accumulated external and internal load were highly similar between groups. Instead, the TH group reached significantly higher values than the BH group in multiple external intensity variables, such as total distance per minute and the number of low-, moderate- and high-intensity accelerations per minute (p = 0.004-0.001). There were no differences in the mean heart rate between groups. The TH group's training external intensity was also closer to match intensity in multiple variables, such as total distance and the number of low- and moderate-intensity accelerations and decelerations compared to the BH group (p = 0.029-0.001). These findings suggest that more successful teams achieved higher external intensity for the same internal response, and their average external training intensity was closer to match demands. Thus, it seems plausible that TH players had better physical qualities and their training prepared them better for matches than BH.

This study aimed to analyze the evolution of repetition velocity throughout a set until failure in the bench-press exercise and to analyze the relationships between the percentage of performed repetitions (%Rep) regarding the maximum number of repetitions that can be completed (MNR) and the percentage of velocity loss (VL) in women. Sixteen women performed one set until failure with four different intensities (50%, 60%, 70%, and 80% of one-repetition maximum, 1RM). Two-testing sessions were performed with 50% and 80% 1RM to evaluate data stability. The level of significance was set at p ≤ 0.05. A close relationship was observed between the magnitude of VL and the %Rep (R² = 0.85-0.92) and a low standard error of the estimation (6.85-9.81%). Regarding reliability, the MNR showed a coefficient of variation (CV) of 16.1% and 20.8% for 50% and 80% 1RM, respectively. Regarding the %Rep for a given VL (from 15% VL), CVs were: 6.3-19.6%, being higher when VL reached in the set was lower. This study shows the usefulness of monitoring VL to estimate, with considerable precision, the %Rep in women. However, the %Rep when a given VL was reached revealed only satisfactory absolute reliability from a certain VL threshold (>15% VL).

This study aimed to determine the optimal inter-set rest periods that would maximize the number of repetitions completed before surpassing various cut-off velocities (COVs) during the prone bench pull exercise. Twenty-three physically active individuals, 15 men and 8 women, participated in six random testing sessions. Each session included four sets of the prone bench pull exercise performed with maximum intent on a Smith machine at 75% of the one-repetition maximum (1RM). The length of the inter-set rest interval (1 [R1], 3 [R3], and 5 [R5] min) and COV used (0.65 m•s^-1 [COV_0.65] and 0.55 m•s^-1 [COV_0.55]) varied between sessions. Longer inter-set rest periods led to a higher volume of repetitions (R5 > R3 > R1), whereas the differences between the rest protocols were larger for COV_0.55 (R1: 28.4 ± 6.0 repetitions; R3: 36.4 ± 9.4 repetitions; R5: 41.1 ± 11.4 repetitions) compared to COV_0.65 (R1: 24.2 ± 7.3 repetitions; R3: 25.4 ± 10.1 repetitions; R5: 28.3 ± 9.7 repetitions). Increasing the number of sets negatively impacted the number of completed repetitions for R1 using both COV_0.65 and COV_0.55, as well as for R3 using COV_0.55. The fastest velocity of the set (MV_fastest) did not differ between the inter-set rest protocols for COV_0.65, while for COV_0.55, R3 and R5 provided a greater MV_fastest than R1 for sets 2-4. These findings suggest that the duration of inter-set rest periods is an important factor to consider when aiming to maximize mechanical performance across multiple sets of the prone bench pull exercise.

Small-sided games (SSGs) refer to game formats where there are variations in the pitch size, the number of players, and rules as compared to official soccer matches. The purpose of this study was to assess the relationship between GPS-derived external loads and the SSGs' area per player (ApP) in elite youth soccer players to identify whether the ApP influenced GPS-derived external load measures to estimate external load variables from SSGs with different densities (i.e., ApP100: the ApP <150 m²•player^-1; ApP200: the ApP ranged from 151 to 250; ApP300: the ApP > 251 m²•player^-1). A cumulative count of 978 individual observations was undertaken, encompassing 15 diverse SSG configurations. The results showed moderate and large correlations between the ApP and external load measures for both U19 and U16 soccer players. The ApP300 induced higher locomotor activities than the ApP100 and the ApP200. However, the ApP100 showed higher mechanical (accelerations and decelerations) values compared to ApP200 and ApP300 conditions for both age groups. It was found that an ApP of less than 150 m²•player^-1 in SSGs did not stimulate enough high-speed distance relative (HSDR), very high-speed distance relative (VHSDR) and sprint distance relative (SDR) compared to official matches in youth soccer players. However, the same ApP overestimated mechanical variables such as total high accelerations and decelerations relative to time (THACCR and THDECR, respectively). The findings of this study have the potential to facilitate the effective management of training loads tailored to specific fitness components of players.

In the field of mental health, eating disorders (EDs) are an important subject of research, especially regarding athletes. This study examined the risk of EDs, orthorexia nervosa (ON), and body perception among elite soccer players, focusing on the impact of body composition. Conducted from March to April 2024 with 51 players from the elite and 1^st division clubs, the research utilized the Eating Attitudes Test (EAT-26), the Düsseldorf Orthorexia Scale (DOS), and the Body Esteem Scale (BES) alongside body composition analysis via Direct Segmental Multi-Frequency Bioelectrical Impedance Analysis (DSM-BIA). Findings indicated a significant prevalence of ED risk among players, with more than half showing potential symptoms. Body composition analyses revealed that players with a higher fat mass had an increased ED risk, while muscle mass did not correlate significantly with ED attitudes. Regarding ON, approximately one-third of athletes were at risk, although no significant relationship was found between ON and body composition variables. In terms of body image, players generally viewed their bodies moderately, rating physical fitness, sex drive, and health positively. However, a higher body fat was associated with lower ratings in upper body strength, indicating perceived physical limitations. This study highlights the necessity for targeted interventions to manage the high prevalence of EDs among elite soccer players and promote healthier body image perceptions, emphasizing the low relationship between body esteem and the likelihood of developing EDs or ON.

Running-related knee injuries are associated with high and repetitive quadriceps contractions. Infrapatellar straps are commonly recommended for the prevention and management of those injuries. The effects of infrapatellar straps have been investigated in terms of quadriceps activations. However, these indexes cannot accurately characterize the quadriceps forces, which directly contribute to knee injuries. This study aimed to quantify quadriceps forces during running performed with and without infrapatellar straps based on OpenSim. Experimental data from 18 healthy participants were recorded using a 10-camera motion capture system and two force plates when they performed running at self-selected speeds with and without infrapatellar straps. OpenSim was used to estimate muscle forces, muscle activity, joint kinematics, and joint kinetics. The use of infrapatellar straps significantly reduced peak quadriceps forces (p < 0.001), accumulated forces of quadriceps (p < 0.001), and peak knee extension moments (p < 0.001). Among the four distinct muscles of the quadriceps, the vastus lateralis contributed the most to the reduction in quadriceps muscle forces. Strapping did not result in a significant change in rectus femoris forces (p > 0.05). The use of infrapatellar straps results in lower vastus muscle forces, and thus could be helpful in managing and preventing running-related knee injuries. However, infrapatellar straps may have little effect in people with an excessively forceful rectus femoris.

This study compared young female soccer players' tactical, conditional, and emotional responses during two small-sided games (SSGs), without restrictions (SSG_free), and introducing an additional rule (SSG_relationship: if a player touches an opponent just before she receives the ball, her team wins the ball back with an indirect free kick). Fourteen developmental U14 players participated in two 4 × 6-min seven-a-side games (six each, plus goalkeepers) on a 50-m long × 30-m wide field. Players' positional data were collected using a GPS to assess their tactical performance (central tendency and entropy measures of the surface area, distance between players and to the nearest opponent, and stretch and spatial exploration indices) and conditional performance (total and low-moderate, high, very high speed, sprinting distance covered, and the number of accelerations and decelerations). Participants also rated their perceived enjoyment and competence using the BECS scale. Tactical central tendency measures were higher during SSG_free (p < 0.05) than in SSG_relationship, but no differences were apparent for entropy and conditional measures (p > 0.05). From bout to bout, central tendency measures of tactical variables decreased more frequently during SSG_free than SSG_relationship. Entropy measures and conditional performance hardly varied between bouts. Enjoyment and perceived competence levels were similar for both SSGs. The findings indicate that modifying the interaction between opponents affects players' tactical responses more than conditional responses when compared with free play. Specifically, touching an opponent before they receive the ball may encourage players to play closer to their opponents during training tasks.

This study examined the effects of different inspiratory muscle training (IMT) on lactate concentration and utilization during high-intensity exercises. Participants were divided into the following three groups: a chronic inspiratory training group (CRG), an acute inspiratory training group (ARG), and a control group (CG). Participants in the CRG accomplished IMT at an exercise intensity of 60-90% of the maximum inspiratory pressure (MIP) with 30 breaths twice a day for 8 weeks, and those in the ARG performed IMT at an intensity of 40-50% of the MIP for approximately 20 min in the pre-training warm-up phase three times a week. Body composition tests, maximum oxygen uptake, anaerobic power tests, and lactate concentrations of participants were evaluated before and after the intervention. Three consecutive anaerobic power tests (Wingate) were performed to observe changes in lactate concentration and utilization during high-intensity exercises. Blood lactate concentrations were measured immediately at the end of each anaerobic power test, after a 75-s rest, and during passive rest at the 2^nd, 3^rd, 4^th, 5^th, 10^th, and 15^th min of recovery. The results of the analysis of variance (ANOVA) revealed a significant decrease in blood lactate concentration only in the CRG immediately after the first Wingate test, whereas significant differences in the ARG and the CG were observed after the third Wingate test. After the last Wingate test, a significant decrease was observed after 5 min of recovery in the CRG and after 10 and 15 min of passive rest in both training groups. Herein, we conclude that IMT decreases blood lactate concentration after intense exercise and accelerates lactate utilization during recovery.