Aerodynamic drag of modern soccer balls

Soccer balls such as the Adidas Roteiro that have been used in soccer tournaments thus far had 32 pentagonal and hexagonal panels. Recently, the Adidas Teamgeist II and Adidas Jabulani, respectively having 14 and 8 panels, have been used at tournaments; the aerodynamic characteristics of these balls have not yet been verified. Now, the Adidas Tango 12, having 32 panels, has been developed for use at tournaments; therefore, it is necessary to understand its aerodynamic characteristics. Through a wind tunnel test and ball trajectory simulations, this study shows that the aerodynamic resistance of the new 32-panel soccer ball is larger in the high-speed region and lower in the middle-speed region than that of the previous 14- and 8-panel balls. The critical Reynolds number of the Roteiro, Teamgeist II, Jabulani, and Tango 12 was ~2.2 × 10⁵ (drag coefficient, C_d ≈ 0.12), ~2.8 × 10⁵ (C_d ≈ 0.13), ~3.3 × 10⁵ (C_d ≈ 0.13), and ~2.4 × 10⁵ (C_d ≈ 0.15), respectively. The flight trajectory simulation suggested that the Tango 12, one of the newest soccer balls, has less air resistance in the medium-speed region than the Jabulani and can thus easily acquire large initial velocity in this region. It is considered that the critical Reynolds number of a soccer ball, as considered within the scope of this experiment, depends on the extended total distance of the panel bonds rather than the small designs on the panel surfaces.

Evaluation and management of children and adolescents with sports-related concussion

Concussions are common sport injuries, and are particularly common among children and adolescents involved in organized sports and recreational activities. Symptoms of concussion can be subtle, and may be overlooked by athletes, coaches/trainers and parents. If a child or youth sustains a concussion, they should immediately be removed from play and assessed by a physician as soon as possible. The athlete should rest from physical and cognitive activities to allow for recovery from concussion. Once symptoms have completely resolved at rest, the athlete can progress through a medically supervised stepwise exertion protocol before being medically cleared to return to play. It is imperative that everyone involved in child and youth sports be aware of the signs and symptoms of concussion so that an accurate and timely diagnosis can be made, and proper evaluation and management instituted. The present position statement replaces the previous document published in 2006.

Elevated body mass index and body fat percentage are associated with decreased physical fitness in soccer players aged 12-14 years

Purpose

Adolescents are in increased risk for the development of obesity, while sport has been suggested as an effective means against adolescent obesity. The objectives of this study were to examine (a) the prevalence of overweightness/obesity, (b) the relationship between body mass index (BMI) and body fat percent (BF), and (c) the association between BMI, BF and physical fitness in adolescent soccer players.

Methods

Members (n=136, aged 13.1±0.6 yr) of competitive soccer clubs were examined for physical and physiological characteristics.

Results

Based on international BMI cut-off points, 19.9% (n=27) of participants were classified as overweight. BMI was highly correlated with BF (r=0.77, P<0.001). BMI and BF were in inverse relationship with aerobic power (r= − 0.29, P<0.001; r= − 0.44, P<0.001, respectively), maximal anaerobic power (r= − 0.23, P=0.009; r= − 0.47, P<0.001) and local muscular endurance (r= − 0.36, P<0.001; r= − 0.67, P<0.001).

Conclusions

The strong relationship between BMI and BF suggest the further use of BMI in adolescent soccer players. The findings confirmed previous observations in the general population about the negative effect of overweight and fatness on physical fitness. The prevalence of overweightness among participants was similar with what is observed in general population. Therefore, sport participation cannot guarantee physiological body mass and body composition, and it is necessary to prescribe exercise targeting body mass and fat control.

Physique and body composition in soccer players across adolescence

Purpose

Although the contribution of physique and body composition in soccer performance was recognized, these parameters of physical fitness were not well-studied in adolescent players. Aim of this study was to investigate physique and body composition across adolescence.

Methods

Male adolescents (N=297 aged 12.01–20.98 y), classified into nine one-year age-groups, child (control group, N=16 aged 7.34–11.97 y) and adult players (control group, N=29 aged 21.01–31.59 y), all members of competitive soccer clubs, performed a series of anthropometric measures (body mass, height, skinfolds, circumferences and girths), from which body mass index (BMI), percentage of body fat (BF%), fat mass (FM), fat free mass (FFM) and somatotype (Heath-Carter method) were calculated.

Results

Age had a positive association with FM (r=0.2, P<0.001) and FFM (r=0.68, P<0.001), and a negative association with BF (r=−0.12, P=0.047). Somatotype components changed across adolescence as well; age was linked to endomorphy (r=−0.17, P=0.005), mesomorphy (r=0.14, P=0.019) and ectomorphy (r=−0.17, P=0.004). Compared with age-matched general population, participants exhibited equal body mass, higher stature, lower body mass index and lower BF.

Conclusion

During adolescence, soccer players presented significant differences in terms of body composition and physique. Thus, these findings could be employed by coaches and fitness trainers engaged in soccer training in the context of physical fitness assessment and talent identification.

Angular deformities of the lower limb in children

Angular deformities of the lower limbs are common during childhood. In most cases this represents a variation in the normal growth pattern and is an entirely benign condition. Presence of symmetrical deformities and absence of symptoms, joint stiffness, systemic disorders or syndromes indicates a benign condition with excellent long-term outcome. In contrast, deformities which are asymmetrical and associated with pain, joint stiffness, systemic disorders or syndromes may indicate a serious underlying cause and require treatment.

Little is known about the relationship between sport participation and body adaptations during growth. Intense soccer participation increases the degree of genu varum in males from the age of 16. Since, according to some investigations, genu varum predisposes individuals to more injuries, efforts to reduce the development of genu varum in soccer players are warranted. In this article major topics of angular deformities of the knees in pediatric population are practically reviewed.

Sport and eating disorders - understanding and managing the risks

There is strong and consistent evidence that eating disorders are prevalent in sport and especially in weight sensitive sports such as endurance, weight category and aesthetic sports as well as jumping events. These illnesses are not only common but lead to significant physical and psychological morbidity and impaired performances.Sports organizations, and by extension the professionals whose job it is to help and support athletes, have important roles in dealing with these conditions. Preventative practices can be adopted if there is an understanding of how the sports environment contributes to the development of eating disorders. Some disorders can be difficult to detect especially in a sports environment and simple screening instruments are available. Athletes may also need help to access appropriate treatment whilst they are recovering.In many sports prevention, screening and support programs have been developed for a variety of medical conditions or sportsrelated injuries. Similar programs should be developed for eating disorders.