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Caleb D. Johnson, Jereme Outerleys, and Irene S. Davis

Several open-source platforms for markerless motion capture offer the ability to track 2-dimensional (2D) kinematics using simple digital video cameras. We sought to establish the performance of one of these platforms, DeepLabCut. Eighty-four runners who had sagittal plane videos recorded of their left lower leg were included in the study. Data from 50 participants were used to train a deep neural network for 2D pose estimation of the foot and tibia segments. The trained model was used to process novel videos from 34 participants for continuous 2D coordinate data. Overall network accuracy was assessed using the train/test errors. Foot and tibia angles were calculated for 7 strides using manual digitization and markerless methods. Agreement was assessed with mean absolute differences and intraclass correlation coefficients. Bland–Altman plots and paired t tests were used to assess systematic bias. The train/test errors for the trained network were 2.87/7.79 pixels, respectively (0.5/1.2 cm). Compared to manual digitization, the markerless method was found to systematically overestimate foot angles and underestimate tibial angles (P < .01, d = 0.06–0.26). However, excellent agreement was found between the segment calculation methods, with mean differences ≤1° and intraclass correlation coefficients ≥.90. Overall, these results demonstrate that open-source, markerless methods are a promising new tool for analyzing human motion.

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Danica Janicijevic and Amador Garcia-Ramos

This systematic review aimed to synthesize the current evidence on the feasibility of volitional reaction time (RT) tests to evaluate the information processing abilities of athletes. Four databases were searched, and, finally, 38 studies exploring the reliability, validity, or sensitivity of RT tests were included. Seven studies explored the reliability, which ranged from poor to excellent, while only three studies explored the validity of RT tests. The most important downside of the majority of the implemented RT tests is their nonspecific nature (i.e., stimulus and response did not resemble the sports actions). Sports scientists should focus on developing RT tests that are specific for each sport and refine the testing procedures to obtain accurate, reproducible, and sensitive measurements of RT.

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Sebastian S. Sandgren, Emma Haycraft, and Carolyn R. Plateau

Eating psychopathology symptoms are common in athletes; however, it is unknown which symptoms are detected and to what extent by sport professionals. This study aimed to develop and evaluate a self-report questionnaire to explore which features of eating psychopathology in athletes are detected by sport professionals, and how observation of these symptoms might vary. Thirty-one questions were developed and 232 sport professionals (56% male) participated in the study. Exploratory Factor Analysis revealed a 20-item, five-factor solution (Negative Affect, Dieting Practices, Fear of Eating in Social Contexts, Bingeing and Purging, and Compulsive Exercise). Participants most frequently reported observing athletes’ dieting practices, while symptoms of a fear of eating in social contexts were observed least frequently. This study has developed and preliminarily tested the Athlete Eating Psychopathology Observation Questionnaire (AEPOQ), which now requires further validation. The findings provide important directions for education initiatives with sport professionals regarding identification of eating psychopathology symptoms.

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David Trouilloud, Sandrine Isoard-Gautheur, and Valentin Roux

Using a person-centered approach, this study was conducted to identify (a) specific athlete profiles in terms of degree of discrepancy between their self-appraisals and the reflected appraisals of their coach and (b) the relations between these profiles and athlete burnout. Athletes (N = 369; Mage = 21.15 years) fulfilled measures of self-appraisals, reflected appraisals of their coach, and burnout. Latent profile analysis allowed the identification of three profiles: concordance (84%), positive discrepancy (11%), and negative discrepancy (5%). Analyses revealed relationships between athletes’ profile membership and the three dimensions of burnout: emotional and physical exhaustion, sport devaluation, and reduced sense of accomplishment. More specifically, results indicated that athletes with a positive discrepancy profile (i.e., who rated themselves more positively than they think their coaches see them) were more at risk of burnout. This study contributes to existing research on psychosocial determinants of athlete burnout in the context of the coach–athlete relationship.

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Thomas O. Minkler, Sam Zizzi, Blake Costalupes, and D. Jake Follmer

Existing mindfulness literature in sport primarily focuses on manualized mindfulness protocols, while less is known about athlete experiences with mindfulness outside of interventions. The purpose of the present study was to explore student-athlete experiences with and readiness to practice mindfulness. Using convenience and snowball sampling, 205 collegiate athletes completed a mixed-method survey that assessed readiness, trait mindfulness, social support for mindfulness practice, and mindfulness’ perceived effect on performance. Participants were invited to comment on benefits, barriers, or adverse experiences during their practice. Athletes with long-term experience had significantly higher mindfulness scores than those with less experience; they also perceived that mindfulness had significantly greater effects on performance than those not practicing. Various benefits and barriers were expressed across stages of readiness, though roughly 6%–10% of participants reported an adverse effect of mindfulness practice. It is thus important for practitioners to consider readiness levels and previous experiences in implementing mindfulness interventions.

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Samuel E. Masters and John H. Challis

Soft tissue moves relative to the underlying bone during locomotion. Research has shown that soft tissue motion has an effect on aspects of the dynamics of running; however, little is known about the effects of soft tissue motion on the joint kinetics. In the present study, for a single subject, soft tissue motion was modeled using wobbling components in an inverse dynamics analysis to access the effects of the soft tissue on joint kinetics at the knee and hip. The added wobbling components had little effect on the knee joint kinetics, but large effects on the hip joint kinetics. In particular, the hip joint power and net negative and net positive mechanical work at the hip was greatly underestimated when calculated with the model without wobbling components compared with that of the model with wobbling components. For example, for low-frequency wobbling conditions, the magnitude of the peak hip joint moments were 50% greater when computed accounting the wobbling masses compared with a rigid body model, while for high-frequency wobbling conditions, the peaks were within 15%. The present study suggests that soft tissue motion should not be ignored during inverse dynamics analyses of running.

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Hamid Norasi, Jordyn Koenig, and Gary A. Mirka

The electromyographic (EMG) normalization (often to maximum voluntary isometric contraction [MVIC]) is used to control for interparticipant and day-to-day variations. Repeated MVIC exertions may be inadvisable from participants’ safety perspective. This study developed a technique to predict the MVIC EMG from submaximal isometric voluntary contraction EMG. On day 1, 10 participants executed moment exertions of 100%, 60%, 40%, and 20% of the maximum (biceps brachii, rectus femoris, neck flexors, and neck extensors) as the EMG data were collected. On day 2, the participants replicated the joint moment values from day 1 (60%, 40%, and 20%) and also performed MVIC exertions. Using the ratios between the MVIC EMGs and submaximal isometric voluntary contraction EMG data values established on day 1, and the day 2 submaximal isometric voluntary contraction EMG data values, the day 2 MVIC EMGs were predicted. The average absolute percentage error between the predicted and actual MVIC EMG values for day 2 were calculated: biceps brachii, 45%; rectus femoris, 27%; right and left neck flexors, 27% and 33%, respectively; and right and left neck extensors, both 29%. There will be a trade-off between the required accuracy of the MVIC EMG and the risk of injury due to exerting actual MVIC. Thus, using the developed predictive technique may depend on the study circumstances.

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Yan-Xia Li, Lin Li, Zhi-Qiang Cai, Xu-Xue Zhou, Xiu-Jun Hao, and Li Li

This study aimed to explore the effect of sex and force level on grip force reproduction in healthy adults by conducting a force reproduction task. Participants (n = 28) were instructed to replicate a range of reference grip force levels (10–130 N in 10 N increments). We found that women (absolute error: 16.2 ± 8.7 N) replicated these force levels more accurately than men (absolute error: 23.1 ± 9.5 N) at higher force levels (90–130 N). Furthermore, the force reproductions were most accurate at the 30–50 N range for men and the 50–60 N range for women. These results may offer significant insights into the higher rates of musculoskeletal disorders among women, enabling researchers and clinicians to design novel interventions and tools that can improve grip force perception and reduce hand injury rates in both men and women.