Journal of Human Kinetics最新文献

The purpose of this investigation was to determine if average concentric velocity (ACV) of a single repetition at 70% of one-repetition maximum (1RM), ACV of the first repetition of a set to failure at 70% of 1RM, or the velocity loss during the set could predict the number of repetitions performed in the back squat. Fifty-six resistance-trained individuals participated in the study (male = 41, age = 23 ± 3 yrs, 1RM = 162.0 ± 40.0 kg; female = 15, age = 21 ± 2 yrs, 1RM = 81.5 ± 12.5 kg). After 1RM testing, participants performed single repetition sets with 70% of 1RM and a set to failure with 70% of 1RM. ACV was recorded on all repetitions. Regression model comparisons were performed, and Akaike Information Criteria (AIC) and Standard Error of the Estimate (SEE) were calculated to determine the best model. Neither single repetition ACV at 70% of 1RM (R² = 0.004, p = 0.637) nor velocity loss (R² = 0.011, p = 0.445) were predictive of total repetitions performed in the set to failure. The simple quadratic model using the first repetition of the set to failure ($Y={\beta }_0+{\beta }_1{X}_{ACVFirst}+{\beta }_{2}Z+\epsilon$) was identified as the best and most parsimonious model (R² = 0.259, F = 9.247, p < 0.001) due to the lowest AIC value (311.086). A SEE of 2.21 repetitions was identified with this model. This average error of ~2 repetitions warrants only cautious utilization of this method to predict total repetitions an individual can perform in a set, with additional autoregulatory or individualization strategies being necessary to finalize the training prescription.

The aim of this study was to evaluate functional movement patterns and spinal posture of elite ice hockey players and to examine the association between spinal posture, prevalence of musculoskeletal symptoms and Functional Movement Screen (FMS^TM) scores. The study included 86 elite male ice hockey players aged 18 to 38 years. Sagittal spinal curvatures were measured with a Saunders digital inclinometer, and functional movement patterns were assessed by the FMS^TM. Spinal posture of the studied ice hockey players was characterized by normal kyphosis (46%) or hyperkyphosis (41%) and decreased lumbar lordosis (54%). The mean total FMS^TM score was 14.8. Most of the hockey players (57%) achieved a total FMS^TM score in the range of 14-17 points, whereas 28% had a total FMS^TM score of <14. Seventy-two percent of the studied athletes had at least one asymmetry. Significant differences between performing the movements on the right and the left sides of the body were observed in in-line lunges (p = 0.019) and shoulder mobility sub-tests (p < 0.001). The FMS^TM sub-tests performed with the lowest success rates were rotatory stability and the hurdle step. A lower score in the rotatory stability test is related to shoulder pain. It is highly important to develop appropriate exercise programs to reduce or prevent muscle imbalances in ice hockey players.

Our cross-sectional study aimed to investigate joint specificity of concentric muscle torque enhancement after a maximum eccentric contraction for the knee versus ankle joints across two different movement velocities (120°/s and 180°/s). After a familiarization session, 22 healthy young adults randomly performed concentric (CONC) and maximum eccentric preloaded concentric (EccCONC) muscle strength tests of the knee extensors and ankle plantar flexors of the non-dominant leg on an isokinetic strength testing device. We calculated the ratio between EccCONC and CONC (EccCONC/CONC) for all the conditions as the marker of concentric muscle torque enhancement. Separate two-way (joints x velocity) within repeated measures ANOVAs were used to determine joint-specific torque differences at 120°/s and 180°/s. CONC and EccCONC were greater for the knee extensors versus ankle plantar flexors at 120°/s and 180°/s (32.86%-102%; p < 0.001 for both); however, EccCONC/CONC was greater for the ankle plantar flexors than knee extensors at 120°/s (52.4%; p < 0.001) and 180°/s (41.9%; p < 0.001). There was a trend of greater EccCONC/CONC for the knee extensors at 180°/s than 120°/s (6.6%; p = 0.07). Our results show that greater concentric muscle torque enhancement after a maximal eccentric contraction occurs for the ankle plantar flexors versus knee extensors. Whether the joint- specificity of concentric muscle torque enhancement after a maximal eccentric contraction differentially affects sports performance is unknown. Our data provide a reference framework to investigate joint-specific concentric muscle torque enhancement for general and clinical athletic populations.

During the last years, post-activation performance enhancement (PAPE) has gained notorious popularity due to the capacity to improve the acute rate of force development (RFD) using different strategies with different muscle contraction regimes as conditioning stimuli. The aim of the present study was to analyse the role of a maximal isometric post-activation performance enhancement (PAPE) protocol in performance and its effects on the kinematics of the sticking region. Twenty-one trained participants (age 26.4 ± 5.4 years) underwent two experimental sessions: an experimental session consisting of a single set and a single repetition of the bench press at the 93% of 1RM (which is considered a traditional conditioning activity to induce PAPE) (TRAD) and an isometric experimental session (ISO) consisting of 15 maximal voluntary isometric contractions in the sticking region of the medium grip bench press lasting 1 s with a 1 s rest interval between contractions. Both TRAD and ISO experimental conditions improved performance from post0 to post4, post8, post12 and post16, but only the ISO condition improved performance from the start of the lift to the start of the sticking region from pre to post (p < 0.001), and only the ISO condition improved maximum (p = 0.005) and minimum (p = 0.025) peak velocities. The results of this study suggest that short duration maximal voluntary isometric contractions improve the velocity of the lift prior to the initiation of the sticking region, which ultimately improves the impulse and facilitates the lift.

Horizontal foot speed is fundamental for running synchronization and stability, and may also be important for sprinting performance. In this investigation, we quantified the following during steady-speed running: (a) peak forward foot speed during the swing phase, (b) backward foot speed at touchdown, and (c) ground speed difference (GSD), i.e., the difference between forward running speed and backward foot speed at touchdown. We hypothesized that forward and backward foot speed would be significantly and positively correlated with top speed, and that GSD would be significantly and negatively correlated with top speed. Participants (20 male, 20 female) completed 40-m submaximal and maximal-effort running trials, with kinematic data collected from 31-39 m. Across top speed trials, forward foot speed (r = 0.90, p < 0.001) and backward foot speed (r = 0.85, p < 0.001) were significantly and positively correlated with running speed. However, counter to expectations, GSD values slightly increased with top speed (r = 0.36, p = 0.027). These findings indicate that forward and backward foot speeds are important variables for sprinting performance, but faster runners may not necessarily exhibit lower GSD values at top speed.

This study aimed to investigate the effects of 10-week aerobic and unilateral lower extremity resistance training on nerve conduction velocity and amplitude of sensory and motor nerves in diabetic patients with neuropathy. This clinical trial was conducted on twenty women and men (aged 30-60 years old) with diabetic neuropathy. Participants were randomly assigned to one of the two groups: an exercise group (EG; n = 10) and a control group (CG; n = 10). The EG performed a 10-week programme with one session of aerobic exercises (40% to 70% of HR reserve), supplemented with one session of specific lower extremity resistance exercises (60-90 min/day) on the same day for four days per week. The CG subjects performed their regular daily activities. The nerve conduction velocity, amplitude of sensory and motor nerves and glycosylated haemoglobin A1c were measured before and after the intervention. The repeated-measures ANOVA showed a significant increase in the conduction velocity of the sural sensory nerve as well as the peroneal motor nerve (p < 0.01, p < 0.01). The changes in the conduction velocity of the tibial nerve were similar when compared to the control group (p > 0.05). A significantly greater decrease in glycosylated haemoglobin was also observed in the EG group (p < 0.01). Performing 10 weeks of aerobic and specific unilateral lower extremity exercises can improve the function of sensory and motor nerves and improve symptoms in diabetic patients with neuropathy. Given the limited studies in this area, the exact mechanisms of this performance improvement need further examination.

This study analyzes the relative age effect (RAE) among the world's best junior hockey leagues and in the NHL. Despite the prevalence of RAE in ice hockey, past research suggests its fading-reversal over time, which may occur at later stages of athletic development. The hypothesis of the RAE reversal was tested with two sources of raw data files from the 2021-2022 season: 15 of the best international junior and minor professional leagues (N = 7 399) and the NHL (N = 812). Birth quartile distributions were analyzed to verify the prevalence of RAE and quantile regression was used to test the reversal of RAE hypotheses. Advanced hockey metrics were aggregated from multiple data sources and used to compare early born with late born players using birth quartiles. Prevalence of the RAE was verified with crosstabs analyses and quantile regression was used to test the reversal effect. Results indicated that the RAE still prevailed in ice hockey, with higher magnitude in Canadian leagues. Regression analyses showed that late-born junior and minor pro players, despite getting less exposure in terms of games played, attained levels of offensive production similar to those of early born players. Late-born players able to emerge in the NHL performed similarly and sometimes displayed better performance (in some markers). Results suggest that stakeholders should find ways to pay special attention to late born players in talent identification processes and offer them opportunities to develop at the highest levels.

This study aimed to investigate the effects of high load fast and medium tempo back squats using a low number of repetitions on maximal strength and power output. Seventeen participants completed a countermovement jump test and 1-repetition maximum (1-RM) assessment before and after an eight-week intervention. All participants were randomly divided into a fast tempo (FAS: 1/0/1/0) and a medium tempo (MED: 2/0/2/0) resistance training (RT) group and performed three repetitions per set of a Smith back squat exercise with 85% 1-RM intensity. Maximal strength, jump height, peak power and force of the two groups were significantly improved (p < 0.05). In addition, peak velocity significantly increased after the intervention in the FAS group (p < 0.05), but not in the MED group (p > 0.05). A significant interaction effect between training groups was observed for jump height (F (_{1, 30}) = 5.49, p = 0.026, η² = 0.155). However, no significant group by time interaction effects were found between training groups for maximal strength (F (_{1, 30}) = 0.11, p = 0.742, η² = 0.004). Therefore, the two groups showed similar effects in maximal strength, but, compared with the MED group, FAS resistance training with low repetitions caused favorable adaptations in power output in trained men.

Connecting desires for achievement, the satisfaction of basic psychological needs and the perception of fear of failure is one of the most relevant questions in the understanding of negative mental responses in youth athletes. How to act with less fear is what every athlete seeks to feel to enhance their performance actions. This paper aims to shed light on a sample of 681 members of sports teams belonging to different Spanish clubs (391 boys and 290 girls), with a mean age of 16.2 years, and a high sports dedication (75.5% > 5 years of experience; 96.3% > two training sessions/week; 90.3% > 3 hours of training/week). The collected data used self-reports based on the tenets of achievement motivation, Self-Determination Theory, and fear of failure. Those aspects linked to task involvement were positively close to Basic Psychological Needs (BPNs), while those related to ego involvement moved away from task involvement and BPNs. Fear was associated positively and significantly only with ego, and negatively with the rest of the constructs. In the standardized direct effect, positive and significant associations were observed among all constructs except between an ego-involving climate and basic psychological needs satisfaction. The association between a task-involving climate and BPNs was significant in fostering relationships among group members, as well as in improving interpersonal cohesion, empathic understanding processes, and reducing fear of failure in youth athletes.

The objective of this study was to compare the impact of cambered and standard barbells used during the bench press exercise on the number of performed repetitions and mean velocity during a bench press training session that included 5 sets performed to volitional failure at 70% of one-repetition maximum (1RM) (for each barbell type). An additional objective was to determine whether there would be any difference in neuromuscular fatigue assessed by peak velocity changes during bench press throws performed 1 and 24 hours after the cessation of each session. The research participants included 12 healthy resistance-trained men. Participants performed 5 sets of the bench press exercise to volitional failure against 70% of 1RM with the cambered or standard barbell. The Friedman's test showed an overall trend of a significant decrease in the mean velocity (p < 0.001) and a number of performed repetitions (p < 0.001) from the first to the fifth set (p < 0.006 and p < 0.02, respectively for all) under both conditions, yet neither bar showed significant differences between the corresponding sets. Two-way ANOVA indicated a significant main effect of time (p < 0.001) for peak velocity during the bench press throw. The post-hoc comparisons showed significantly lower peak velocity during the bench press throw one hour after the bench press compared to pre (p = 0.003) and 24-hour post intervention (p = 0.007). Both barbells caused a similar decrease in peak barbell velocity during the bench press throw performed one hour after the bench press training session, with values returning to baseline 24 hours later. This indicates that bench press workouts with either a standard or a cambered barbell present the same training demands.