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Frederick S. Daniels and Daniel M. Landers

This study investigated heart rate (HE) and respiration functioning during rifle shooting to test hypotheses derived from Schwartz's (1979) systems and disregulation theory, and to compare biofeedback with verbal instruction in developing awareness and control of autonomic patterns. Male subjects (N = 8) were pretested to determine HE and respiration patterns affecting performance. They were then divided into two equal groups and given either auditory biofeedback or verbal instruction. The auditory-biofeedback group received continuous pattern feedback through earphones while the verbal instruction group received only presession instruction without feedback. Each group trained for five sessions of 40 shots each. Following training, two 40-shot sessions were conducted. A scaled interview was administered pre- and posttraining to determine awareness/control of autonomic functioning. Compared to the verbal instruction group, the results showed that the biofeedback group significantly improved performance and consistency of the desired pattern and had significantly greater awareness/control of the autonomic pattern. The results supported the systems and disregulation theory as well as the viability of biofeedback for altering imbalances within the systems.

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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.

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Pascal David, Mohamad Halimi, Isabelle Mora, Pierre-Louis Doutrellot and Michel Petitjean

Ankle sprains are among the most common sport-related injuries and can lead to chronic ankle instability. Impaired sensorimotor function of the ankle musculature is often suggested as a cause. The current study sought to assess and compare the isokinetic performance and electromyographic patterns of evertor and invertor muscles in patients with chronic ankle instability and in a control group. Twelve patients with chronic ankle instability and twelve healthy subjects were included. Isokinetic eccentric and concentric testing at various angular velocities was performed for eversion and inversion movements. The corresponding myoelectric activities of the fibularis longus and tibialis anterior muscles were quantified from surface electromyographic recordings by computing average root mean square values. Patients had lower myoelectric activity of the evertor and invertor muscles than controls did; this difference could account for the eccentric weakness associated with ankle instability. Functional strength ratios revealed a dynamic strength imbalance in unstable ankle patients and that may contribute to recurrent injury. Our findings suggest that rehabilitation programs for unstable ankle patients must be focused on the motor control of eccentric contractions of the ankle evertors and invertors, to boost these muscles’ contribution to ankle stabilization.

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Mark Kluemper, Tim Uhl and Heath Hazelrigg

Context:

Imbalanced shoulder muscles might cause poor posture in swimmers, which has been implicated as potential cause of injury.

Objective:

To determine whether a training program can reduce forward shoulder posture.

Design:

Prospective pseudorandomized.

Setting:

College swimming pool.

Participants:

39 competitive swimmers (age 16 ± 2 years) divided into an exercise group (n = 24) and a control group (n = 15).

Intervention:

The experimental group performed a partner-stretching program on the anterior shoulder muscles and a strengthening regimen focusing on the posterior shoulder muscles for 6 weeks. The control group participated in normal swim-training activities.

Main Outcome Measures:

Shoulder posture was measured as the distance from the anterior acromion to a wall using a double-square method.

Results:

The experimental group significantly reduced the distance of the acromion from the wall in a resting posture (–9.6 ± 7.3 mm) as compared with the control group (–2.0 ± 6.9 mm).

Conclusions:

A training routine might reduce the forward shoulder posture present in most competitive swimmers.

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Luiz Henrique Palucci Vieira, Felipe de Souza Serenza, Vitor Luiz de Andrade, Lucas de Paula Oliveira, Fábio Pamplona Mariano, Juliana Exel Santana and Paulo Roberto Pereira Santiago

The aims of the current study were to analyze a kick from 10 m in a futsal context and the parameters of muscular strength using an isokinetic dynamometer in a laboratory environment, performed with the dominant (DL) and nondominant lower limbs (NDL). Seventeen professional elite players participated. Kicking performance was evaluated from the second penalty mark. Next, athletes completed a strength evaluation with an isokinetic dynamometer at speeds of 60°⋅s–1, 180°⋅s–1, and 300°⋅s–1. Significant differences were observed for hip (15.64 ± 3.44; 13.97 ± 2.62), ankle (63.19 ± 8.90; 52.55 ± 8.72), foot (82.31 ± 7.93; 68.41 ± 7.85), and ball (99.74 ± 8.45; 88.31 ± 7.93) speeds (km⋅h–1), and average power at 180°⋅s–1 (325.59 ± 40.47; 315.79 ± 39.49 W), but not for accuracy (1.33 ± 0.57; 1.66 ± 0.77 m) between the DL and NDL, respectively. Few moderate correlations were observed in the DL (r = .54–.64) or NDL (r = .53–.55) between the kinematic variables of kick and muscular strength parameters (P < .05). We conclude that highly trained players present asymmetries in kicking motion; however, the imbalance in muscular strength is very small. We recommend that specific court tests be conducted to reliably characterize kicking performance in futsal. Success in kicking seems to be too variable and complex to be totally predicted only by joints, foot and ball speed, and lower limb muscular strength parameters.

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Jean-Benoît Morin and Pierre Samozino

Recent studies have brought new insights into the evaluation of power-force-velocity profiles in both ballistic push-offs (eg, jumps) and sprint movements. These are major physical components of performance in many sports, and the methods the authors developed and validated are based on data that are now rather simple to obtain in field conditions (eg, body mass, jump height, sprint times, or velocity). The promising aspect of these approaches is that they allow for more individualized and accurate evaluation, monitoring, and training practices, the success of which is highly dependent on the correct collection, generation, and interpretation of athletes’ mechanical outputs. The authors therefore wanted to provide a practical vade mecum to sports practitioners interested in implementing these power-force-velocity–profiling approaches. After providing a summary of theoretical and practical definitions for the main variables, the authors first detail how vertical profiling can be used to manage ballistic push-off performance, with emphasis on the concept of optimal force–velocity profile and the associated force–velocity imbalance. Furthermore, they discuss these same concepts with regard to horizontal profiling in the management of sprinting performance. These sections are illustrated by typical examples from the authors’ practice. Finally, they provide a practical and operational synthesis and outline future challenges that will help further develop these approaches.

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Naryana Cristina Mascarin, Claudio Andre Barbosa de Lira, Rodrigo Luiz Vancini, Alberto de Castro Pochini, Antonio Carlos da Silva and Marilia dos Santos Andrade

Context:

Imbalance in shoulder-rotator muscles has been considered a risk factor for injuries in handball. Strength training programs (STPs) may play an important preventive role.

Objective:

To verify the effects of an STP using elastic bands on shoulder muscles and ball-throwing speed.

Design:

Randomized and prospective controlled trial.

Setting:

Exercise physiology laboratory.

Participants:

Thirty-nine female handball players were randomly assigned to an experimental (EG, n = 21, 15.3 ± 1.1 y) or a control (CG, n = 18, 15.0 ± 0.8 y) group.

Intervention:

The EG performed the STP with elastic-band progressive exercises for 6 wk before regular handball training, and the CG underwent only their regular training.

Main Outcome Measures:

Before and after the STP, both groups underwent a ball-throwing-speed test and isokinetic test to assess shoulder internal- (IR) and external-rotator muscle performance.

Results:

Average power values for IR muscles presented a significant group-vs-time interaction effect (F = 3.9, P = .05); EG presented significantly higher values after the STP (P = .03). Ball speed presented higher values in EG after the STP in standing (P = .04) and jumping (P = .03) throws. IR peak-torque values and balance in shoulder-rotator muscles presented no group-vs-time interaction effect.

Conclusions:

STP using elastic bands performed for 6 wk was effective to improve muscle power and ball speed for young female handball players.

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Julie Minikel-Lacocque

Gender-based discrimination in sport is omnipresent and manifests in various forms, including unequal pay, disparate access to facilities, and imbalanced media exposure. This discrimination also extends to those female athletes who do not meet stereotypical notions of how females should look and how they should move on the sporting field. Four gender nonconforming youth athletes who have faced gender and gender-identity discrimination in sport were recruited for this study, as well as their families and two of their coaches. A qualitative case study was conducted and data from in-depth interviews with each participant, one focus group with the young athletes, and observational field notes are analyzed. Through the lens of Critical Feminist Theory, this study examines the gender and gender-identity discrimination these young athletes have endured, the perpetrators of which are adults charged with organizing and regulating youth sport. The study finds that these athletes are repeatedly accused of lying about their identities, that they are often subjected to gender identity denial, and that their bodies are routinely policed and objectified. Implications for institutions of higher education, sport management, coaches, referees, and fans are discussed and include targeted education on nuanced understandings of gender, sex, misgendering, and gender identity denial. This study also calls for sport to believe youth athletes regarding their identities as well as for a re-examination of the gendered structure of youth sport.

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Jaak Jürimäe

Physical exercise is known to regulate energy balance. Important to this regulatory system is the existence of several peptides that communicate the status of body energy stores to the brain and are related to the body fatness including leptin, adiponectin and ghrelin. These hormones assist in regulating energy balance as well as somatic and pubertal growth in children. It appears that rather few studies have investigated the responses of leptin, adiponectin and ghrelin to acute exercise and these studies have demonstrated no changes in these peptides as a result of exercise. Leptin levels are decreased and may remain unchanged advancing from prepuberty to pubertal maturation in young male and female athletes. A limited number of studies indicate that adiponectin levels are not different between prepubertal and pubertal athletes and untrained controls. However, in certain circumstances circulating adiponectin could be increased in young athletes after onset of puberty as a result of heavily increased energy expenditure. Ghrelin levels are elevated in young sportsmen. However, pubertal onset decreases ghrelin levels in boys and girls even in the presence of chronically elevated energy expenditure as seen in young athletes. Ghrelin may also be used as an indicator of energy imbalance across the menstrual cycle in adolescent athletes. There are no studies with high-molecular-weight adiponectin and only very few studies with acylated ghrelin responses to acute exercise and chronic training have been performed in young athletes. Since these forms of adiponectin and ghrelin have been thought to be bioactive forms, further studies with these specific forms of adiponectin and ghrelin are needed. In conclusion, further studies should be conducted to investigate the response of these hormones to acute and chronic negative energy balance to better understand their role in regulating energy balance during growth and maturation in young athletes.

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Ruth L. Chimenti, Sara A. Scholtes and Linda R. Van Dillen

Many risk factors have been identified as contributing to the development or persistence of low back pain (LBP). However, the juxtaposition of both high and low levels of physical activity being associated with LBP reflects the complexity of the relationship between a risk factor and LBP. Moreover, not everyone with an identified risk factor, such as a movement pattern of increased lumbopelvic rotation, has LBP.

Objective:

The purpose of this study was to examine differences in activity level and movement patterns between people with and people without chronic or recurrent LBP who participate in rotation-related sports.

Design Case:

Case-control study.

Setting:

University laboratory environment.

Participants:

52 people with chronic or recurrent LBP and 25 people without LBP who all play a rotation-related sport.

Main Outcome Measures:

Participants completed self-report measures including the Baecke Habitual Activity Questionnaire and a questionnaire on rotation-related sports. A 3-dimensional motion-capture system was used to collect movement-pattern variables during 2 lower-limb-movement tests.

Results:

Compared with people without LBP, people with LBP reported a greater difference between the sport subscore and an average work and leisure composite subscore on the Baecke Habitual Activity Questionnaire (F = 6.55, P = .01). There were no differences between groups in either rotation-related-sport participation or movement-pattern variables demonstrated during 2 lower-limb-movement tests (P > .05 for all comparisons).

Conclusions:

People with and people without LBP who regularly play a rotation-related sport differed in the amount and nature of activity participation but not in movement-pattern variables. An imbalance between level of activity during sport and daily functions may contribute to the development or persistence of LBP in people who play a rotation-related sport.