Workload and injury incidence in elite football academy players

ABSTRACT

The aim of this study was to prospectively analyse the relationship between workloads and injury in elite football academy players. Elite football academy players (n = 122) from under-19 (U19) and under-21 (U21) of a professional football team competing in UEFA European Cups were followed during 5 seasons. Injuries were collected and absolute workload and workload ratios (4-weeks, 3-weeks, 2-weeks and week-to-week) calculated using a rolling days method with the help of the session Rate of Perceived Exertion. There was no association between absolute workload or workload ratio with the injury incidence in the U19. In the U21, the level of cumulative absolute workloads during 3-weeks (RR = 1.39, p = 0.026) and during 4-weeks (RR = 1.40, p = 0.019) were associated with an increase in injury. There was no association between workload ratio and injury in U21. The significant link between high cumulated 3-weeks and 4 weeks workloads and injury in U21 confirmed the requirement to monitor the internal subjective workload in U21 in order to prevent injury. Further studies exploring the relationships between workload and injury are required in football academy.     

Classroom Teachers' Perceptions of the Impact of Barriers to Teaching Physical Education on the Quality of Physical Education Programs

A major aim of the current study was to determine what classroom teachers perceived to be the greatest barriers affecting their capacity to deliver successful physical education (PE) programs. An additional aim was to examine the impact of these barriers on the type and quality of PE programs delivered. This study applied a mixed-mode design involving data source triangulation using semistructured interviews with classroom teachers (n = 31) and teacher-completed questionnaires (n = 189) from a random sample of 38 schools. Results identified the key factors inhibiting PE teachers, which were categorized as teacher-related or institutional. Interestingly, the five greatest barriers were defined as institutional or out of the teacher's control. The major adverse effects of these barriers were evident in reduced time spent teaching PE and delivering PE lessons of questionable quality.     

Physical Activity Levels and Prompts in Young Children at Recess: A Two-Year Study of a Bi-Ethnic Sample

Abstract

We investigated physical activity and encouragement for activity in a bi-ethnic cohort during recess. Activity and associated interactions of 287 children were recorded at preschool and again 2.2 years later. Children expended nearly twice as much energy at preschool recess than at elementary recess. Activity levels declined as recess time elapsed. At preschool, European-American children engaged in more moderate to vigorous activity than Mexican-Americans. As participants moved to elementary school, teachers' prompts to be active decreased and prompts from peers increased. Boys and girls received similar amounts of activity prompts at preschool, but prompts to boys increased over time. The findings suggest that school environments could be altered to promote healthful physical activity among young children.     

Relationship between Motor Achievement and Selected Personality Factors of Junior and Senior High School Boys

Abstract

This study was conducted for the purpose of determining the relationship between specific factors of personality adjustment and levels of motor achievement in a select group of junior and senior high school boys. Pertinent scales from the 16 Personality Factor Questionnaire and the Guilford Zimmerman Temperament Survey were administered to 154 subjects for the purpose of determining existing personality characteristics. The motor achievement data were collected from administration of the McCloy General Motor Ability and Motor Capacity Test. The data were statistically analyzed through the use of the Pearson product-moment correlation technique, the t test, and the multiple regression technique. The study concluded that, (a) individual group dependance was a factor in extent of exhibited motor achievement and, (b) that levels of motor achievement were predictable with the use of grouped measured personality characteristics.     

A Biomechanical Analysis of Four Sprint Start Positions

Abstract

The sprint starts of 12 skilled collegiate sprinter!hurdlers were filmed for four different sprint start conditions. Ground reaction forces were collected for the first step out of the blocks and velocities through a 2-m speed trap immediately following the first support phase were recorded. The subjects employed their preferred right-left leg placement in the blocks, while the anterior–posterior spacing of the front block with respect to the starting line and the amount of forward lean in the set position were varied. Four positions were constructed that accounted for anthropometric differences. The four positions consisted of combinations of two arm orientations (forward lean and perpendicular to ground) and two front block to starting line distances (bunched and elongated). Kinematic data were reduced to provide center of mass position and velocity measures and analyzed for critical periods throughout the starting action. Selected critical events from the first step kinetic records were also analyzed. The results indicated that the elongated starting positions resulted in greater horizontal displacement, greater propelling impulse, increased first step toe-off velocity, and greater average velocity through a 2-m speed trap. Arm orientation effects were less well defined. Forward lean tended to result in greater vertical velocity at block clearance and horizontal velocity at first step toe-off, whereas perpendicular arm positioning resulted in greater 2-m speed trap velocity.     

Diet and Physical Activity Patterns of Obese and Nonobese Elementary School Children

Abstract

The caloric intake and physical activity patterns of 50 fifth grade students were studied to determine the relative contributions of diet and physical inactivity in the development of obesity. On the basis of tricep skinfold measurements, the subjects were divided into four groups or levels of obesity. Seven-day diet recall records were then obtained with the cooperation of the children's parents. Activity patterns were studied by filming the subjects during games of high and low organization and during free play. Indexes of the duration and intensity of activity were derived from the film analysis. The caloric intake and physical activity patterns of the four groups were compared by the Duncan Multiple Range Test. Using the combined scores for all groups, correlation coefficients were computed to determine the relationship between (1) skinfold measures and total caloric intake, (2) skinfold measures and activity patterns, and (3) total caloric intake and activity patterns. The relative inactivity of the obese children and the relatively similar diets of all children regardless of body fat, as well as the significant negative relationship between activity indexes and body fat tended to support the contention that inactivity may be as important or more important than excessive caloric intake in the development and maintenance of childhood obesity.     

Precompetitive anxiety and motor performance: A psychophysiological examination

Male volunteer subjects (27) completed a 5‐week habituation period during which practise was undertaken on three motor performance tests. Tests were of serial reaction time, visuomotor ability and muscular power. Following stabilization of performance subjects entered an experimental period where they performed the tests before an evaluative audience on one occasion, and against a matched opponent, also before an evaluative audience on the final occasion. Preperformance measures were obtained of neuroendocrine activity, anticipatory heart rate and state anxiety. Significant precompeti‐tion elevations in state anxiety, heart rate and adrenaline levels were observed, supporting the notion that the exposure was perceived as stressful by subjects. Significant correlations were obtained between adrenaline levels and both state and trait anxiety scores. Results showed a significant increase in performance compared to habituation levels for all three tests in the audience condition. In the competitive situation against a matched opponent, performance level for the visuomotor and power tests declined significantly compared to the previous session performed before an audience. Serial reaction time performance showed a continuing upward trend, although failing to achieve significance. Changes in performance are discussed with reference to cue‐utilization explanations and broader cognitive resource limitations.