This study investigated the process that contributes to the decay of short-term motor memory regarding force reproduction. Participants performed tonic flexion of the right index finger with the target force feedback (criterion phase) and reproduced this force level without feedback 3, 10, 30, or 60 s after the end of the criterion phase (recall phase). The constant error for force reproduction was significantly greater than zero, indicating that information about the somatosensation and/or motor command in the criterion phase is positively biased. Constant and absolute errors were not influenced by the retention interval, indicating that neither bias nor error represents the decay of short-term motor memory over time. Variable error, defined as SD of bias (force in the recall phase minus that in the criterion phase), increased as the retention interval increased. This indicates that the decay of short-term motor memory is represented by the increase in inconsistency of memory bias among the trials. The correlation coefficient of the force between the criterion and recall phases with 3-s retention interval was greater than that with longer intervals. This is explained by the view that the contribution of the information of the practiced force to the force reproduction process is great within 3 s after the end of the practice, but the additional contribution of the noise information becomes greater after this time, causing lesser relative contribution of the information of the practiced force to the force reproduction process.
Koichi Hiraoka, Masaya Ishimoto, Mai Kishigami, Ryota Sakaya, Asahi Sumimoto, and Kazuki Yoshikawa
Francesco Frontani, Marco Prenassi, Viviana Paolini, Giovanni Formicola, Sara Marceglia, and Francesca Policastro
The goal of the study is to analyze the kinematics and provide an EMG analysis of the support limb during an instep kick in adolescent players. We set a video camera, two torque transducers on the knee, and EMG sensors. A sample of 16 adolescent soccer players between 10 and 12 years old performed kicks. The kinematics shows a p = .039 on frontal plane (dominant 15.4 ± 1.8, nondominant 18.8 ± 1.7); the EMG analysis shows a p = .04 on muscular activation timing for the vastus medialis. A difference between the legs on the frontal plane emerges. Moreover, a huge difference on sagittal plane between the adolescent pattern and adult pattern exists (15° in adolescent population, 40° in adult population). The result shows a greater activation of the vastus medialis in the nondominant leg; probably, in this immature pattern, the adolescents use this muscle more than necessary.
Jacqueline A. Augustine, Sarah Rothstein, Larissa True, and Kevin D. Dames
Context: A variety of gait retraining interventions are available to modify running mechanics associated with musculoskeletal injuries. These often require specialized equipment and/or personnel to prompt the runner toward specific strategies. Objective: To determine whether instructing female recreational runners to “run quietly” could decrease impact force characteristics. Design: Cohort. Setting: Research laboratory. Participants: Fifteen healthy female recreational runners (24  y) volunteered. Interventions: Baseline testing occurred on day 1 (baseline), a posttraining assessment occurred on day 2 (training), and a final assessment occurred 1 week after training on day 3 (follow-up). A smartphone decibel measuring app was used to provide biofeedback on the decibel level of foot strike on day 2 (training). Main Outcomes: Peak vertical force, impact transient, peak and average vertical loading rate, ground contact time, and running economy were collected on each day and compared via repeated-measures analyses of variance. Results: Vertical ground reaction force was lower at follow-up (2.30 bodyweights [BW]) versus baseline (2.39 BW, P = .023) and training (2.34 BW, P = .047). Maximal loading rate decreased from baseline (69.70 BW·s−1) to training (62.24 BW·s−1, P = .021) and follow-up (60.35 BW·s−1, P = .031). There was no change in running economy. Conclusions: Our findings demonstrate that simple instructions to “run quietly” can yield immediate and sustained reductions in impact force profiles, which do not influence running economy.
Kim Tolentino, Tucker Readdy, and Johannes Raabe
Workaholism (i.e., working excessively and compulsively) is associated with negative physical, psychological, and social consequences. Researchers have previously examined antecedents of workaholism, but the experiences of sport coaches have not yet been investigated. This study explored (a) differences in National Collegiate Athletic Association Division I coaches’ workaholism, as well as need satisfaction and frustration based on gender, coaching role, gender of athletes coached, age, and years of coaching experience; and (b) how coaches’ perceptions of their three basic psychological needs are associated with tendencies to work excessively and compulsively. A total of 873 National Collegiate Athletic Association Division I coaches participated in the research. Data analyses revealed significant differences in participants’ workaholism as well as need satisfaction and frustration. Structural equation modeling indicated a significant relationship between reported levels of workaholism and perceptions of the three needs. Findings illustrate the importance of basic psychological needs in preventing coaches’ workaholism and maintain optimal functioning.
Nima Dehghansai, Alia Mazhar, Ross Pinder, Joseph Baker, and Ian Renshaw
The current study explored coach and athlete reactions and challenges leading up to the Tokyo 2020 Paralympic Games, with a specific focus on the impacts of the COVID-19 pandemic and the Games’ postponement. Nine Australian Paralympic coaches (n = 3) and athletes (n = 6) shared their experiences in semistructured interviews. The thematic analysis highlighted how participants experienced the emergence of the pandemic in different ways, but all were relieved when the late but eventual decision to postpone the Games was made. Regarding lockdown periods (i.e., social-distancing restrictions), some coaches and athletes thrived under the new reality (i.e., training from home, online coaching) while others had more difficulty adjusting. Furthermore, results highlight the many uncertainties still remaining, which continue to influence participants’ sport and personal lives. The experiences of coaches and athletes during the COVID-19 pandemic sheds light on strategies and resources that could support Paralympic coaches and athletes during current and future crises.
Deirdre Lyons, Philip Clarke, and Robert C. Dempsey
Limited research into professional rugby union players’ experiences of seeking formal support for their mental health exists, despite comparable rates of mental health issues among elite rugby players with the general population. This qualitative study explored professional players’ actual experiences of accessing Rugby Players Ireland’s mental well-being service, via separate focus group discussions with professional players (n = 5) and player development managers (n = 4) who refer players into the service. An inductive reflexive thematic analysis identified three themes detailing players’ (a) journey to disclosure of their mental health difficulties, (b) their expectations and engagement with the well-being service, and (c) participants’ reflections on mental health experiences in a high-performance environment. Embedding mental health as a key component of player development in high-performance environments, improving mental health literacy, normalizing mental health experiences, and encouraging help-seeking would help promote player well-being and support holistic development alongside sporting performance.
Blanca De-la-Cruz-Torres, Beatriz Romero-Rodríguez, and Carlos Romero-Morales
Context: The performance of sprints during male soccer matches usually is slow medium paced, where the soleus and gastrocnemius (ankle plantar flexors) play a very important role. As in male soccer, soleus injuries should be considered in female soccer; but the scientific evidence is very limited in this case. Design: Pilot clinical trial study. Objective: To determine whether adding an ultrasound-guided percutaneous needle electrolysis (US-guided PNE) technique to a specific exercise program improved perceived pain at stretching and at palpation, ankle dorsiflexion range of motion, muscle fatigue, and sport performance in women soccer players with soleus injury. Methods: This pilot study recruited 20 female players with chronic soleus injury (type 1, characterized by hypoechoic image) who were assigned to one of 2 groups: an experimental group (exercise program + US-guided PNE; n = 10) or a control group (exercise program + sham stimulation; n = 10). Pain intensity, dorsiflexion range of motion, knee-flexion heel raise test, curve sprint test, and the global rating of change scale were analyzed at baseline and after treatment (4 wk) and there was no further follow-up. Results: Pain intensity at palpation and at stretching, dorsiflexion range of motion, and heel raise test values showed significant improvements (P < .05) between pretreatment and posttreatment for both groups, however, no significant differences were observed between groups. Curve sprint tests did not show significant differences between pretreatment and posttreatment for either group or between groups. However, the percentage of changes always revealed better values in favor of the PNE group. Both groups showed good player satisfaction with the therapies. Conclusion: The application of the US-guided PNE combined with a specific exercise program may cause clinical benefits in the treatment of female soccer players with soleus injury.
Meghan Lamers, Erika E. Howe, Geoffrey A. Power, and Leah R. Bent
To determine how heating affects dynamic joint position sense at the knee, participants (n = 11; F = 6) were seated in a HUMAC NORM dynamometer. The leg was passively moved through extension and flexion, and participants indicated when the 90° reference position was perceived, both at baseline (28.74 ± 2.43 °C) and heated (38.05 ± 0.16 °C) skin temperatures. Day 2 of testing reduced knee skin feedback with lidocaine. Directional error (actual leg angle–target angle) and absolute error (AE) were calculated. Heating reduced extension AE (baseline AE = 5.46 ± 2.39°, heat AE = 4.10 ± 1.97°), but not flexion. Lidocaine did not significantly affect flexion AE or extension AE. Overall, increased anterior knee-skin temperature improves dynamic joint position sense during passive knee extension, where baseline matching is poorer. Limited application of lidocaine to the anterior thigh, reducing some skin input, did not influence dynamic joint position sense, suggesting cutaneous receptors may play only a secondary role to spindle information during kinesthetic tasks. Importantly, cutaneous input from adjacent thigh regions cannot be ruled out as a contributor.
Kwok Ng, Sean Healy, Wesley O’Brien, Lauren Rodriguez, Marie Murphy, and Angela Carlin
For the first time, data on children and adolescents with disabilities in Ireland are reported based on the Active Healthy Kids Global Alliance Para Report Card methodology. The most recent data from the last 10 years were used in the grading process (A+ to F), and indicators with insufficient data were graded as incomplete. Of the 10 indicators from the Global Matrix Para Report Cards, grades were assigned to Overall Physical Activity (F), Organized Sport (D), Active Transport (D−), Sedentary Behaviors (D−), Family & Peers (C), School (C−), Community & Environment (B−), and Government (B). Irish disability sport organizations were invited to assess the research-led audit and provided commentary around the final grading. The contextual discussion of the grades is presented through the lens of strengths, weaknesses, opportunities, and threats with the purpose being to provide direction for the reduction of physical activity disparities among children with disabilities.
Yen-Ting Chen, Shengai Li, Yingchun Zhang, Ping Zhou, and Sheng Li
Startling acoustic stimulation (SAS) causes a transient effect on the primary motor cortex (M1) nonreflexively. It reduces the cortical excitability at rest, but not during voluntary contraction. However, the effect of SAS on intracortical activity is not clear. The purpose of this study was to investigate the SAS effect on short-interval intracortical inhibition and intracortical facilitation using transcranial magnetic stimulation (TMS). Eleven healthy individuals performed isometric elbow flexion at 10% of maximum voluntary contraction on the dominant side with a real-time visual target (i.e., M1 preactivation) or at rest. TMS was delivered to the M1 ipsilateral to elbow flexion without or with SAS delivered 90 ms prior to TMS. There were three TMS delivery conditions: (a) single pulse, (b) short-interval intracortical inhibition, and (c) intracortical facilitation. TMS-induced motor-evoked potential (MEP) was compared between predetermined TMS and SAS conditions at rest and during ipsilateral voluntary contraction. We confirmed that SAS decreased the MEP amplitude at rest, but not during M1 preactivation. SAS caused task-specific effects on intracortical excitability. Specifically, SAS increased intracortical facilitation at rest and during voluntary contraction. However, SAS decreased short-interval intracortical inhibition only during M1 preactivation. Collectively, our results suggest that SAS transiently influences the motor cortex excitability, possibly via its activation of higher centers, to achieve a visually guided goal-directed task.