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Shihui Chen, Ernest Lange, Paul Miko, Jiabei Zhang and Daniel Joseph

The purpose of this study was to investigate the effectiveness of the progressive time delay (PTD) procedure on teaching gross motor skills to adult males with severe mental retardation. A multiple probe design across three skills and replicated across 4 participants was utilized. Results indicated that a PTD procedure with a 0 to 5 s delay was effective in teaching 4 participants three gross motor skills (tee-ball batting, softball pitching, croquet striking) over a period of 13 weeks. Data on effectiveness were analyzed in terms of the number of instructional sessions (M = 9.58), the number of trials (M = 105.41), the number of min (M = 84.66), and the number of performing errors to criterion (M = 4.08%). A maintenance level (M = 96.87%) was also determined across 4 participants and three skills on the 1st, 4th, 14th, and 24th sessions after terminating the PTD instruction.

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Carsten H. Larsen, Dorothee Alfermann, Kristoffer Henriksen and Mette K. Christensen

The purpose of this article is to present practitioners and applied researchers with specific details of an ecological-inspired program and intervention in a professional football (soccer) club in Denmark. Based on an ecological agenda, the aim is to reinforce the culture of psychosocial development in the daily practice of a professional football academy, provide the skills required to succeed at the professional level and create stronger relations between the youth and professional departments. The authors suggest six principles as fundamental governing principles to inform an intervention inspired by the holistic ecological perspective. Descriptions of the intervention program and findings are presented in four interconnected steps. Insights are provided into delivery of workshops, the supervision of the coach, on-pitch training, evaluation of the program, and integrating sport psychology as a part of the culture within the club.

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André Roca, Paul R. Ford, Allistair P. McRobert and A. Mark Williams

The ability to anticipate and to make decisions is crucial to skilled performance in many sports. We examined the role of and interaction between the different perceptual-cognitive skills underlying anticipation and decision making. Skilled and less skilled players interacted as defenders with life-size film sequences of 11 versus 11 soccer situations. Participants were presented with task conditions in which the ball was located in the offensive or defensive half of the pitch (far vs. near conditions). Participants’ eye movements and verbal reports of thinking were recorded across two experiments. Skilled players reported more accurate anticipation and decision making than less skilled players, with their superior performance being underpinned by differences in task-specific search behaviors and thought processes. The perceptual-cognitive skills underpinning superior anticipation and decision making were shown to differ in importance across the two task constraints. Findings have significant implications for those interested in capturing and enhancing perceptual-cognitive skill in sport and other domains.

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Eric L. Sauers, Danelle L. Dykstra, R. Curtis Bay, Kellie Huxel Bliven and Alison R. Snyder

Context:

Throwing-related arm injuries are common in softball pitchers and may lead to diminished health-related quality of life (HRQOL). Arm symptoms such as pain have been reported to be more common in healthy overhead athletes than nonoverhead athletes. Furthermore, more frequent shoulder symptoms and lower shoulder function have been demonstrated in athletes with self-reported history of shoulder injury.

Objective:

To evaluate the relationship between arm injury history, current pain rating, and HRQOL assessed via 2 region-specific patient self-report scales in high school and college softball pitchers.

Design:

Cross-sectional.

Setting:

High school and college athletic training facilities.

Participants:

25 female softball pitchers (10 high school, 15 college; 18 ± 2 y, 169 ± 7.6 cm, 67.5 ± 10.3 kg).

Intervention:

Self-reported arm injury history and rating of current pain and HRQOL were collected during the late season.

Main Outcome Measures:

A self-report questionnaire of arm injury history and current pain rating was used, and HRQOL was assessed via 2 region-specific scales: the Disabilities of the Arm, Shoulder, and Hand (DASH) and the Functional Arm Scale for Throwers© (FAST©). Correlational analysis was used to evaluate the relationships between arm injury history, current pain rating, and the DASH total score and sport module and the FAST total score, pitching module, and subscales.

Results:

A history of arm injury from throwing was reported by 64% of participants, 31% of whom had to cease activity for more than 10 d. The most common site of arm time-loss injury was the shoulder (81%). Mild to severe shoulder pain during the competitive season was reported by 60% of respondents. The DASH and the FAST total scores were significantly correlated (r = .79, P < .001). Respondent rating of shoulder pain correlated significantly with the DASH total (r = .69) and sports module (r = .69) and the FAST total (r = .71), pitching module (r = .65), and pain (r = .73), impairment (r = .76), functional-limitation (r = .79), disability (r = .52), and societal-limitations (r = .46) subscales.

Conclusion:

History of arm injury is common in female high school and college softball pitchers. Severe injury and elevated pain are associated with lower HRQOL that extends beyond the playing field.

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Vassilios Gourgoulis, Nikolaos Aggeloussis, Georgios Mavridis, Alexia Boli, Panagiotis Kasimatis, Nikolaos Vezos, Argyris Toubekis, Panagiotis Antoniou and Georgios Mavrommatis

The purpose of the current study was to investigate the acute effect of sprint resisted front crawl swimming on the propulsive forces of the hand. Eight female swimmers swam 25 m with maximal intensity, with and without added resistance. A bowl with a capacity of 2.2, 4 and 6 L was used as low, moderate and high added resistance, respectively. The underwater motion of the swimmer’s right hand was recorded using 4 cameras (60 Hz) and the digitization was undertaken using the Ariel Performance Analysis System. Repeated-measures ANOVA revealed that the velocity of the hand, the pitch and the sweepback angles of the hand, as well as the magnitude and the relative contribution of the drag and lift forces were not significantly modified and thus the magnitude of the resultant force did not change. Moreover, the magnitude of the effective force, as well as the angle formed between the resultant force and the axis of the swimming propulsion were not significantly affected. Thus, it could be concluded that resistance added as in this study did not alter the pattern of the propulsive hand forces associated with front crawl sprinting.

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L. R. Brawley, R. C. Powers and K. A. Phillips

This experiment examined if a general expectancy for male superiority biased subjective evaluation of motor performance. Alternatively, sex bias could be specific to tasks involving muscular work. If the former, rather than the latter explanation is viable, a bias favoring males would be generalized to a task not obviously sex typed: motor accuracy. Observers, 22 of each sex, watched the softball pitching accuracy of performers of both sexes. Performer accuracy was trained and tested to ensure equality. Observers estimated preperformance accuracy, then observed three throws, estimating postperformance after each. Unlike the muscular endurance experiments, neither preperformance nor postperformance analysis revealed a sex bias. Thus a task-specific expectancy rather than general expectancy for male superiority was suggested to explain evaluation sex bias of previous muscular endurance experiments. Surprisingly, mean error magnitude of postperformance estimates was significantly greater for performers observed second than those viewed first, although actual performer accuracy was not different. This finding appears analogous to psychophysical judgment results in which successive stimulus judgments were conditions sufficient to cause estimation error. Suggestions are made for future research.

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John H. Lawrence III and T. Richard Nichols

Muscle actions are often defined within a single anatomical reference plane. Yet animals must control posture and movement within a three-dimensional (3-D) environment, responding to a 3-D array of perturbing forces. Based on information gained regarding the 3-D muscle mechanics at the cat ankle joint complex (companion paper), we decided to study how alterations in the 3-D AJC orientation might affect ankle joint postural control. We used a 6 degree-of-freedom force-moment sensor to assess the affect of ankle joint orientation on the 3-D isometric joint torques evoked by electrical stimulation of muscles crossing the ankle joint complex (AJC) in the deeply anesthetized cat. An orthogonal axis system was established at the designated ankle rotation center, such that pitch (flexion-extension), yaw (abduction-adduction), and roll (inversion-eversion) axis torques were calculated. Experimental results suggest that both the magnitude and sign of extra-sagittal torques from the gastrocnemius muscles are joint angle dependent. Also, the hind limb levering system stabilizes the AJC against large yaw and roll rotations away from the control position.

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Simon Roberts, Grant Trewartha and Keith Stokes

Purpose:

To assess the validity of a digitizing time–motion-analysis method for field-based sports and compare this with a notational-analysis method using rugby-union match play.

Method:

Five calibrated video cameras were located around a rugby pitch, and 1 subject completed prescribed movements within each camera’s view. Running speeds were measured using photocell timing gates. Two experienced operators digitized video data (operator 1 on 2 occasions) to allow 2-dimensional reconstruction of the prescribed movements.

Results:

Accuracy for total distance calculated was within 2.1% of the measured distance. For intraoperator and interoperator reliability, calculated distances were within 0.5% and 0.9%, respectively. Calculated speed was within 8.0% of measured photocell speed with intraoperator and interoperator reliability of 3.4% and 6.0%, respectively. For the method comparison, two 20-minute periods of rugby match play were analyzed for 5 players using the digitizing method and a notational time–motion method. For the 20-minute periods, overall mean absolute differences between methods for percentage time spent and distances covered performing different activities were 3.5% and 198.1 ± 138.1 m, respectively. Total number of changes in activity per 20 minutes were 184 ± 24 versus 458 ± 48, and work-to-rest ratios, 10.0%:90.0% and 7.3%:92.7% for notational and digitizing methods, respectively.

Conclusion:

The digitizing method is accurate and reliable for gaining detailed information on work profiles of field-sport participants and provides applied researchers richer data output than the conventional notational method.

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Darcy M. Brown, Dan B. Dwyer, Samuel J. Robertson and Paul B. Gastin

The purpose of this study was to assess the validity of a global positioning system (GPS) tracking system to estimate energy expenditure (EE) during exercise and field-sport locomotor movements. Twenty-seven participants each completed a 90-min exercise session on an outdoor synthetic futsal pitch. During the exercise session, they wore a 5-Hz GPS unit interpolated to 15 Hz and a portable gas analyzer that acted as the criterion measure of EE. The exercise session was composed of alternating 5-minute exercise bouts of randomized walking, jogging, running, or a field-sport circuit (×3) followed by 10 min of recovery. One-way analysis of variance showed significant (P < .01) and very large underestimations between GPS metabolic power– derived EE and oxygen-consumption (VO2) -derived EE for all field-sport circuits (% difference ≈ –44%). No differences in EE were observed for the jog (7.8%) and run (4.8%), whereas very large overestimations were found for the walk (43.0%). The GPS metabolic power EE over the entire 90-min session was significantly lower (P < .01) than the VO2 EE, resulting in a moderate underestimation overall (–19%). The results of this study suggest that a GPS tracking system using the metabolic power model of EE does not accurately estimate EE in field-sport movements or over an exercise session consisting of mixed locomotor activities interspersed with recovery periods; however, is it able to provide a reasonably accurate estimation of EE during continuous jogging and running.

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Yin-Chou Lin, Angela Thompson, Jung-Tang Kung, Liang-Wei Chieh, Shih-Wei Chou and Jung-Charng Lin

Context:

Elbow injuries are widely reported among baseball players. The elbow is susceptible to injury when elbow-flexor and -extensor forces are imbalanced during pitching or throwing. Assessment of muscle-strength ratios may prove useful for diagnosing elbow injury.

Objective:

The purpose of this study was to assess the relationship between the elbow-flexor and -extensor functional isokinetic ratios and elbow injury in baseball players.

Design:

Retrospective study.

Setting:

Biomechanics laboratory.

Participants:

College baseball players with (n = 9) and without (n = 12) self-reported elbow pain or loss of strength were recruited.

Intervention and Main Outcome Measures:

Trials were conducted using a dynamometer to assess dominant-arm flexor and extensor concentric and eccentric strength at angular velocities of 60° and 240°/s. Functional isokinetic ratios were calculated and compared between groups.

Results:

Regression analysis revealed that a ratio of biceps concentric to triceps concentric strength greater than 0.76 (the median value) significantly predicted elbow injury (P = .01, odds ratio of injury = 24). No other ratios or variables (including position played) were predictive of injury status.

Conclusions:

These findings suggest that the ratio of biceps concentric to triceps concentric functional strength strongly predicts elbow-injury status in baseball players. Assessment of this ratio may prove useful in a practical setting for training purposes and both injury diagnosis and rehabilitation.