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John H. Hollman, Nicholas J. Beise, Michelle L. Fischer and Taylor L. Stecklein

Context: Examining the coordinated coupling of muscle recruitment patterns may provide insight into movement variability in sport-related tasks. Objective: The purpose of this study was to examine the relationship between coupled gluteus maximus and medius recruitment patterns and hip-adduction variability during single-limb step-downs. Design: Cross-sectional. Setting: Biomechanics laboratory. Participants: Forty healthy adults, including 26 women and 14 men, mean age 23.8 (1.6) years, mean body mass index 24.2 (3.1) kg/m2, participated. Interventions: Lower-extremity kinematics were acquired during 20 single-limb step-downs from a 19-cm step height. Electromyography (EMG) signals were captured with surface electrodes. Isometric hip-extension strength was obtained. Main Outcome Measures: Hip-adduction variability, measured as the SD of peak hip adduction across 20 repetitions of the step-down task, was measured. The mean amplitudes of gluteus maximus and gluteus medius EMG recruitment were examined. Determinism and entropy of the coupled EMG signals were computed with cross-recurrence quantification analyses. Results: Hip-adduction variability correlated inversely with determinism (r = −.453, P = .018) and positively with entropy (r = .409, P = .034) in coupled gluteus maximus/medius recruitment patterns but not with hip-extensor strength nor with magnitudes of mean gluteus maximus or medius recruitment (r = −.003, .081, and .035; P = .990, .688, and .864, respectively). Conclusion: Hip-adduction variability during single-limb step-downs correlated more strongly with measures of coupled gluteus maximus and medius recruitment patterns than with hip-extensor strength or magnitudes of muscle recruitment. Examining coupled recruitment patterns may provide an alternative understanding of the extent to which hip neuromuscular control modulates lower-extremity kinematics beyond examining muscle strength or EMG recruitment magnitudes.

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Christopher Michael Brogden, Lewis Gough and Adam Kelly

Context: Physiological fitness testing, such as the Yo-Yo Intermittent Recovery Test (YYIR) is a key requirement of the Elite Player Performance Plan, introduced by the English Premier League. Eccentric hamstring strength has been identified as a risk factor for hamstring injuries in soccer players, with fatigue highlighted to further exasperate this issue. Objective: The aim of the current study was to examine the effect of the YYIR level 1 (YYIR1) on eccentric knee flexor strength assessed using the NordBord in youth soccer players. Design: Experimental design. Setting: Soccer club academy. Participants: A total of 67 male academy soccer players (age = 16.58 [0.57] y; height = 175.45 [5.85] cm; mass = 66.30 [8.21] kg) volunteered to participate in the current study during the English competitive soccer season. Main Outcome Measures: Participants conducted eccentric hamstring strength assessments using the NordBord prior to and immediately postcompletion of the YYIR1, with outcome measures of peak force and peak force relative to body mass recorded. Results: Paired t tests highlighted increased absolute eccentric knee flexor strength values (P < .001) immediately post-YYIR1 for both the dominant and nondominant limbs, with the same trend (P < .001) observed for eccentric strength relative to body mass. Conclusions: The results of this study indicate that the YYIR1 does not induce eccentric knee flexor fatigue and as such is not a valid assessment method to assess the effects of fatigue on hamstring function. However, results do suggest that the NordBord may be considered a viable and more accessible alternative to detect pre–post fitness test/fatigue protocol differences in eccentric knee flexor peak strength while working in the field.

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Audrey G. Evers, Jessica A Somogie, Ian L. Wong, Jennifer D. Allen and Adolfo G. Cuevas

The objective of this study was to examine the effectiveness of a pilot mindfulness program for student athletes by assessing mental health, mindfulness ability, and perceived stress before and after the intervention. The mindfulness program was adapted from a program developed at the University of Southern California. The four-session intervention taught the basics of mindfulness, self-care skills, and guided meditations. Participants completed surveys before and after the intervention. Mindfulness ability was assessed with the Cognitive and Affective Mindfulness Scale, mental health was assessed with a modified Short Form Health Survey, and stress was assessed with the Perceived Stress Scale. After the intervention, participants reported improvement in mindfulness ability, t(28) = −2.61, p =  .014, mental health, t(28)  =  −2.87, p =  .008, and a trending improvement in perceived stress, t(28)  =  1.86, p =  .073. A short mindfulness program may be effective for improving mental health and mindfulness ability in collegiate student athletes.

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Luca Correale, Vittoria Carnevale Pellino, Luca Marin, Massimiliano Febbi and Matteo Vandoni

Spatiotemporal parameters of walking are used to identify gait impairments and provide a tailored therapy program. Baropodometric platforms are not often used for measuring spatiotemporal parameters and walking speed and it is required to determine accuracy. The aim of this study was to compare FreeMed® Platform gait outcomes with a validated inertial measurement unit. There were 40 healthy adults without walking impairments enrolled. Each subject walked along a 15-m walkway at self and slow self-selected speed wearing an inertial measurement unit on the FreeMed® Platform. Stride length and time, right and left stance, swing time, and walking speed were recorded. Walking speed, stride length, and step time showed a very high level of agreement at slow walking speed and a high and moderate level of agreement at normal walking speed. FreeMed® Platform is useful to assess gait outcomes and could improve the exercise prescription.

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Joy Khayat, Stéphane Champely, Ahmad Diab, Ahmad Rifai Sarraj and Patrick Fargier

The present study aimed at examining the effect of mental calculation and number comparison on motor performance measured as the movement time of a fast manual-pointing movement. Three experiments, involving a total number of 65 undergraduate subjects, examined the effect of mental subtraction (complex) and, respectively, of (a) mental addition (simple or complex), (b) mental multiplication (simple or complex), and (c) the comparison of dot sets and number comparison. Each number was written in Arabic. The movement times were analyzed by using a multilevel linear mixed-effect model. The results showed significant improvement of manual-pointing movement performance only after the complex calculations and after number comparison. Possible implication of attentional mechanisms specific to this arithmetical activity is further discussed.

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Geovani Messias da Silva and Maria Eduarda Crescencio Bezerra

External focus is a way to guide human movement based on outcome rather than execution, therefore all instructions are provided based on factors present in the environment. The aim of this review is to search information about the effects of external focus in the long jump task and to compare its outcomes with other learning methods. For the research, online database search engines such as PubMed, ScienceDirect, Embase, Cinahl, and Scopus were used from January 2010 to June 2020. About 41 articles were identified by searching the online databases, 12 were discarded because they were duplicates, 11 were excluded due to the content of the abstract, and finally, 5 were excluded after evaluating the content of the full text, leaving 13 articles to be included in this review. This review sought to summarize the findings in the literature on the use of external focus in the practice of long jump. The authors concluded that the external focus is a relevant approach and can be used as a tool for the learning process.

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Xiangyu Liu, Meiyu Zhou, Chenyun Dai, Wei Chen and Xinming Ye

Surface electromyogram-based finger motion classification has shown its potential for prosthetic control. However, most current finger motion classification models are subject-specific, requiring calibration when applied to new subjects. Generalized subject-nonspecific models are essential for real-world applications. In this study, the authors developed a subject-nonspecific model based on motor unit (MU) voting. A high-density surface electromyogram was first decomposed into individual MUs. The features extracted from each MU were then fed into a random forest classifier to obtain the finger label (primary prediction). The final prediction was selected by voting for all primary predictions provided by the decomposed MUs. Experiments conducted on 14 subjects demonstrated that our method significantly outperformed traditional methods in the context of subject-nonspecific finger motion classification models.

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Michele Verdonck, Jacquie Ripat, Peita-Maree Clark, Florin Oprescu, Marion Gray, Lisa Chaffey and Bridie Kean

Wheelchair basketball (WCBB) often includes reverse integration (RI), defined as the inclusion of athletes without impairment in a sport traditionally aimed at athletes with an impairment. This study explored how RI in WCBB was understood by internal stakeholders. Data were gathered from athletes, coaches, and administrators at an Australian club competition and at a Canadian elite training center. Analysis of semistructured interviews with 29 participants led to the identification of eight themes. Collectively, the findings showed that RI was embedded within WCBB, RI was considered to be a way to advance the growth and improve the quality of WCBB as well as a way to increase awareness of WCBB and disability. There were some concerns that RI may not be equitable, as WCBB is a “disability sport.” Stakeholders’ perspectives on RI could provide useful information for sport policymakers, managers, administrators, sports organizations, and athletes interested in further developing WCBB.

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Joshua Berger, Oliver Ludwig, Stephan Becker, Wolfgang Kemmler and Michael Fröhlich

A 17-year-old male road cyclist with unspecific back pain and postural deficiency regarding the depth of the lumbar lordosis (flèche lombaire [fl]) and the upper body tilt (forward trunk tilt [tt]) absolved an 8-week whole-body electromyostimulation (WB-EMS) training to improve performance parameters and health issues. During WB-EMS, muscle groups all over the body are stimulated via external electrodes, thus creating an intensive training stimulus due to the electrically induced involuntary muscle contraction. The athlete’s posture (fl 2.2%, tt 64.3%) and back pain (54%) improved, and trunk strength increased (extension 15.5%, flexion 29.2%). This is the first WB-EMS study of a minor cyclist, suggesting positive effects of WB-EMS as a time-saving strength training method on health and strength parameters.

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Daichi Tomita, Tadashi Suga, Hiromasa Ueno, Yuto Miyake, Takahiro Tanaka, Masafumi Terada, Mitsuo Otsuka, Akinori Nagano and Tadao Isaka

This study examined the relationship between Achilles tendon (AT) length and 100-m sprint time in sprinters. The AT lengths at 3 different portions of the triceps surae muscle in 48 well-trained sprinters were measured using magnetic resonance imaging. The 3 AT lengths were calculated as the distance from the calcaneal tuberosity to the muscle–tendon junction of the soleus, gastrocnemius medialis, and gastrocnemius lateralis, respectively. The absolute 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = −.023 to .064, all Ps > .05). Furthermore, to minimize the differences in the leg length among participants, the 3 AT lengths were normalized to the shank length, and the relative 3 AT lengths did not correlate significantly with personal best 100-m sprint time (r = .023 to .102, all Ps > .05). Additionally, no significant correlations were observed between the absolute and relative (normalized to body mass) cross-sectional areas of the AT and personal best 100-m sprint time (r = .012 and .084, respectively, both Ps > .05). These findings suggest that the AT morphological variables, including the length, may not be related to superior 100-m sprint time in sprinters.