RESUMEN
Decision-making is an essential capability for success in team sport athletes. Good decision-making is underpinned by perceptual-cognitive skills that allow athletes to assess the environment and choose the correct choice from a number of alternatives. Previous research has demonstrated that decision-making can be trained "off-line" by exposing athletes to gameplay scenarios and having them make decisions based on the information presented to them. These scenarios are typically presented on television monitors or using life-size projections but recent advances in immersive video capabilities provide opportunities to improve the fidelity of training by presenting a realistic, 360° view of the competition environment. The purpose of this study was to assess the effectiveness of immersive video training and whether training would improve decision-making performance in elite, youth basketball players (male and female). A training group completed 10 or 12 immersive video (360° video presented in a head-mounted display) training sessions in which they viewed and responded to gameplay scenarios across 3-weeks while the control group only participated in their usual training routine. Performance was assessed on an immersive video test and during small-sided games (SSG). The male training group had a large, non-significant improvement on immersive test score (+4.0 points) and in the SSG (+5.8 points) compared to the male control group (+0.3 points and +1.0 points, respectively). While both the female control group (+9.7 points) and training group (7.4 points) had large improvements in the immersive training test, only the female control improved their performance in the SSG (+6.9 points). Despite the mixed findings, there may be benefit for using immersive video for training decision-making skill in team sports. The implications of these findings (e.g., gender of the actors used to create stimuli, variety of scenarios presented) and the limitations of the experiment are discussed.
RESUMEN
It has been suggested that deep squats could cause an increased injury risk of the lumbar spine and the knee joints. Avoiding deep flexion has been recommended to minimize the magnitude of knee-joint forces. Unfortunately this suggestion has not taken the influence of the wrapping effect, functional adaptations and soft tissue contact between the back of thigh and calf into account. The aim of this literature review is to assess whether squats with less knee flexion (half/quarter squats) are safer on the musculoskeletal system than deep squats. A search of relevant scientific publications was conducted between March 2011 and January 2013 using PubMed. Over 164 articles were included in the review. There are no realistic estimations of knee-joint forces for knee-flexion angles beyond 50° in the deep squat. Based on biomechanical calculations and measurements of cadaver knee joints, the highest retropatellar compressive forces and stresses can be seen at 90°. With increasing flexion, the wrapping effect contributes to an enhanced load distribution and enhanced force transfer with lower retropatellar compressive forces. Additionally, with further flexion of the knee joint a cranial displacement of facet contact areas with continuous enlargement of the retropatellar articulating surface occurs. Both lead to lower retropatellar compressive stresses. Menisci and cartilage, ligaments and bones are susceptible to anabolic metabolic processes and functional structural adaptations in response to increased activity and mechanical influences. Concerns about degenerative changes of the tendofemoral complex and the apparent higher risk for chondromalacia, osteoarthritis, and osteochondritis in deep squats are unfounded. With the same load configuration as in the deep squat, half and quarter squat training with comparatively supra-maximal loads will favour degenerative changes in the knee joints and spinal joints in the long term. Provided that technique is learned accurately under expert supervision and with progressive training loads, the deep squat presents an effective training exercise for protection against injuries and strengthening of the lower extremity. Contrary to commonly voiced concern, deep squats do not contribute increased risk of injury to passive tissues.
Asunto(s)
Articulación de la Rodilla/fisiología , Pierna/fisiología , Postura/fisiología , Columna Vertebral/fisiología , Levantamiento de Peso/fisiología , Atletas , Fenómenos Biomecánicos , Humanos , Estrés MecánicoRESUMEN
UNLABELLED: Competition-specific conditioning for tournament basketball games is challenging, as the demands of tournament formats are not well characterized. PURPOSE: To compare the physical, physiological, and tactical demands of seasonal and tournament basketball competition and determine the pattern of changes within an international tournament. METHODS: Eight elite junior male basketball players (age 17.8 ± 0.2 y, height 1.93 ± 0.07 m, mass 85 ± 3 kg; mean ± SD) were monitored in 6 seasonal games played over 4 mo in an Australian second-division national league and in 7 games of an international under-18 tournament played over 8 days. Movement patterns and tactical elements were coded from video and heart rates recorded by telemetry. RESULTS: The frequency of running, sprinting, and shuffling movements in seasonal games was higher than in tournament games by 8-15% (99% confidence limits ± ~8%). Within the tournament, jogging and low- to medium-intensity shuffling decreased by 15-20% (± ~14%) over the 7 games, while running, sprinting, and high-intensity shuffling increased 11-81% (± ~25%). There were unclear differences in mean and peak heart rates. The total number of possessions was higher in seasonal than in tournament games by 8% (± 10%). CONCLUSIONS: Coaches should consider a stronger emphasis on strength and power training in their conditioning programs to account for the higher activity of seasonal games. For tournament competition, strategies that build a sufficient aerobic capacity and neuromuscular resilience to maintain high-intensity movements need to be employed. A focus on half-court tactics accounts for the lower number of possessions in tournaments.
Asunto(s)
Rendimiento Atlético/fisiología , Baloncesto/fisiología , Conducta Competitiva/fisiología , Esfuerzo Físico/fisiología , Adolescente , Frecuencia Cardíaca/fisiología , Humanos , MasculinoRESUMEN
Differences in physiological, physical, and technical demands of small-sided basketball games related to the number of players, court size, and work-to-rest ratios are not well characterised. A controlled trial was conducted to compare the influence of number of players (2v2/4v4), court size (half/full court) and work-to-rest ratios (4x2.5 min/2x5 min) on the demands of small-sided games. Sixteen elite male and female junior players (aged 15-19 years) completed eight variations of a small-sided game in randomised order over a six-week period. Heart rate responses and rating of perceived exertion (RPE) were measured to assess the physiological load. Movement patterns and technical elements were assessed by video analysis. There were â¼60% more technical elements in 2v2 and â¼20% more in half court games. Heart rate (86 ± 4% & 83 ± 5% of maximum; mean ± SD) and RPE (8 ± 2 & 6 ± 2; scale 1-10) were moderately higher in 2v2 than 4v4 small-sided games, respectively. The 2v2 format elicited substantially more sprints (36 ±12%; mean ±90% confidence limits) and high intensity shuffling (75 ±17%) than 4v4. Full court games required substantially more jogging (9 ±6%) compared to half court games. Fewer players in small-sided basketball games substantially increases the technical, physiological and physical demands.
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Rendimiento Atlético/fisiología , Baloncesto/fisiología , Frecuencia Cardíaca , Esfuerzo Físico/fisiología , Desempeño Psicomotor/fisiología , Descanso/fisiología , Carrera/fisiología , Adolescente , Adulto , Femenino , Humanos , Masculino , Movimiento , Aptitud Física , Análisis y Desempeño de Tareas , Adulto JovenRESUMEN
It is unclear if increases in 1 repetition maximum (1RM) in quarter squats result in higher gains compared with full depth squats in isometric force production and vertical jump performance. The aim of the research projects was to compare the effects of different squat variants on the development of 1RM and their transfer effects to Countermovement jump (CMJ) and squat jump (SJ) height, maximal voluntary contraction (MVC), and maximal rate of force development (MRFD). Twenty-three women and 36 men (mean age: 24.11 ± 2.88 years) were parallelized into 3 groups based on their CMJ height: deep front squats (FSQ, n = 20), deep back squats (BSQ, n = 20), and quarter back squats (BSQ», n = 19). In addition, a control group (C, n = 16) existed (mean age: 24.38 ± 0.50 years). Experimental groups trained 2 d·wk for 10 weeks with a strength-power block periodization, which produced significant (p ≤ 0.05) gains of the specific squat 1RM. The FSQ and BSQ attained significant (p ≤ 0.05) elevations in SJ and CMJ without any interaction effects between both groups (p ≥ 0.05). The BSQ» and C did not reveal any significant changes of SJ and CMJ. The FSQ and BSQ had significantly higher SJ scores over C (p ≤ 0.05). The BSQ did not feature any significant group difference to BSQ» (p = 0.116) in SJ, whereas FSQ showed a trend toward higher SJ heights over BSQ» (p = 0.052). The FSQ and BSQ presented significantly (p ≤ 0.05) higher CMJ heights over BSQ» and C. Posttest in MVC and MRFD demonstrated no significant changes for BSQ. Significant declines in MRFD for FSQ in the right leg (p ≤ 0.05) without any interaction effects for MVC and MRFD between both FSQ and BSQ were found. Training of BSQ» resulted in significantly (p ≤ 0.05) lower MRFD and MVC values in contrast to FSQ and BSQ. Quarter squat training elicited significant (p ≤ 0.05) transfer losses into the isometric maximal and explosive strength behavior. These findings therefore contest the concept of superior angle-specific transfer effects. Deep front and back squats guarantee performance-enhancing transfer effects of dynamic maximal strength to dynamic speed-strength capacity of hip and knee extensors compared with quarter squats.
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Contracción Isométrica/fisiología , Pierna/fisiología , Músculo Esquelético/fisiología , Entrenamiento de Fuerza/métodos , Análisis de Varianza , Antropometría , Femenino , Humanos , Estudios Longitudinales , Masculino , Fuerza Muscular/fisiología , Análisis y Desempeño de Tareas , Adulto JovenRESUMEN
Junior basketball athletes require a well-designed resistance training program to improve their physical development. Lack of expert supervision and resistance training in junior development pathways may be overcome by implementing an online video-based program. The aim of this study was to compare the magnitude of improvement (change) in physical performance and strength and functional movement patterns of junior basketball athletes using either a fully supervised or an online video-based resistance training program. Thirty-eight junior basketball athletes (males, n = 17; age, 14 ± 1 year; height, 1.79 ± 0.10 m; mass, 67 ± 12 kg; females, n = 21; age, 15 ± 1 year; height, 1.70 ± 0.07 m; mass, 62 ± 8 kg) were randomly assigned into a supervised resistance training group (SG, n = 13), video training group (VG, n = 13) or control group (CG, n = 12) and participated in a 6-week controlled experimental trial. Pre- and posttesting included measures of physical performance (20-m sprint, step-in vertical jump, agility, sit and reach, line drill, and Yo-Yo intermittent recovery level 1), strength (15 s push-up and pull-up), and functional movement screening (FMS). Both SG and VG achieved 3-5% ± 2-4% (mean ± 90% confidence limits) greater improvements in several physical performance measures (vertical jump height, 20-m sprint time, and Yo-Yo endurance performance) and a 28 ± 21% greater improvement in push-up strength compared with the CG. The SG attained substantially larger gains in FMS scores over both the VG (12 ± 10%) and CG (13 ± 8%). Video-based training appears to be a viable option to improve physical performance and strength in junior basketball athletes. Qualified supervision is recommended to improve functional movement patterns in junior athletes.