Reliability of the one-repetition-maximum power clean test in adolescent athletes

Although the power clean test is routinely used to assess strength and power performance in adult athletes, the reliability of this measure in younger populations has not been examined. Therefore, the purpose of this study was to determine the reliability of the 1-repetition maximum (1RM) power clean in adolescent athletes. Thirty-six male athletes (age 15.9 ± 1.1 years, body mass 79.1 ± 20.3 kg, height 175.1 ±7.4 cm) who had >1 year of training experience in weightlifting exercises performed a 1RM power clean on 2 nonconsecutive days in the afternoon following standardized procedures. All test procedures were supervised by a senior level weightlifting coach and consisted of a systematic progression in test load until the maximum resistance that could be lifted for 1 repetition using proper exercise technique was determined. Data were analyzed using an intraclass correlation coefficient (ICC[2,k]), Pearson correlation coefficient (r), repeated measures analysis of variance, Bland-Altman plot, and typical error analyses. Analysis of the data revealed that the test measures were highly reliable demonstrating a test-retest ICC of 0.98 (95% confidence interval = 0.96-0.99). Testing also demonstrated a strong relationship between 1RM measures in trials 1 and 2 (r = 0.98, p < 0.0001) with no significant difference in power clean performance between trials (70.6 ± 19.8 vs. 69.8 ± 19.8 kg). Bland-Altman plots confirmed no systematic shift in 1RM between trials 1 and 2. The typical error to be expected between 1RM power clean trials is 2.9 kg, and a change of at least 8.0 kg is indicated to determine a real change in lifting performance between tests in young lifters. No injuries occurred during the study period, and the testing protocol was well tolerated by all the subjects. These findings indicate that 1RM power clean testing has a high degree of reproducibility in trained male adolescent athletes when standardized testing procedures are followed and qualified instruction is present.     

Echocardiographic characteristics in adolescent junior male athletes of different sport events

The purpose of this study was to examine the effects of different sport activities on cardiac adaptation. Echocardiographic data of 137 athletes and 21 non-athletes were measured and compared in two age groups 15-16 and 17-18 years of age. Athletes belonged into three groups according to their sports activity (endurance events, power athletes, ball game players). The observed variables were related to body size by indices in which the exponents of the numerator and the denominator were matched. Left ventricular hypertrophy was manifest in all athletic groups. Power athletes had the largest mean left ventricular wall thickness (LVWTd) in both age groups. In the older age group differences between the athletic groups were smaller, but the endurance and power athletes had significantly higher wall thickness. Left ventricular internal diameter (LVIDd) was the largest in the endurance athletes, while mean relative muscle mass (LVMM) was the largest in the power athletes. LVMM of the older endurance athletes was significantly larger. Muscular quotient (MQ) was the highest in the endurance athletes; in the 17-18-year group there was no inter-event difference. Bradycardia was most manifest in the endurance athletes and ball game players, power athletes had higher resting heart rates than non-athletic subjects. It can be inferred that endurance training induces firstly an enlargement of the left ventricle what is then followed by an increase of muscle mass. In the studied functional and regulatory parameters no difference was found between the athletic and non-athletic groups.     

Incidence of exercise-induced asthma in adolescent athletes under different training and environmental conditions

The aim of this study was to establish if there were differences in the incidence of exercise-induced bronchospasm between athletes in different sports, which take place under different environmental conditions such as open places, closed courses, and swimming pools with similar exercise intensity (football, basketball, water polo) using the free running test. The study included 90 adolescents (3 groups of 30) aged 14-18 years recruited from academies in northern Greece. All the participants were initially subjected to (a) a clinical examination and cardiorespiratory assessment by a physician and (b) free running test of a 6-minute duration and measurement with a microspirometer of the forced expiratory volume in 1 second (FEV?). Only the participants who had measured a decrease in FEV? ≥ 10% were reevaluated with the microspirometer during a training session. The examination of all the participants during the free running test showed that 22 athletes, that is, 9, 8, and 5 of football, basketball, and water polo athletes, respectively, demonstrated an FEV? ≥ 10 drop. Reevaluation of the 22 participants during training showed that 5 out 9 (55%) football athletes, 4 out of 8 basketball athletes (50%), and none of the 5 athletes of the water polo team displayed a drop of FEV? ≥ 10%. Despite the absence of any significant statistical differences between the 3 groups, the analysis of variances did show a trend of a lower incidence of EIA in the water polo athletes. It was found that a football or basketball game can induce EIA in young athletes but to a lesser degree than the free running test can induce. The water polo can be a safer sport even for participants with a medical history of asthma or allergies.     

Media use and obesity in adolescent females

Objective: In the context of growing public health concern with the obesity rates among children and adolescents, much attention has focused on the role of television as a contributor to the problem. Less attention has been devoted to interactive media (internet surfing and video games), despite the fact that these forms of entertainment are fast gaining in popularity among youth. This study investigated the relative associations of TV viewing and interactive media use with body fat and BMI, controlling for both physical activity participation and cardiovascular fitness. Research Methods and Procedures: Female high‐school adolescents (N = 194) were assessed for cardiovascular fitness (cycle ergometer), percent body fat (DXA), and BMI. Time spent in moderate, vigorous, and sedentary activities was assessed with a 3‐day recall. Results: Multivariate regression analysis showed that only interactive media use was associated with percentage body fat and BMI, and the relationship remained strong even after controlling for physical activity participation and cardiovascular fitness. Discussion: It appears that, among this group of adolescent females, the association between interactive media use and obesity is not explained by a reduction in moderate or vigorous activity commensurate with media use.     

Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports

Dias Quiterio, AL, Canero, EA, Baptista, FM, and Sardinha, LB. Skeletal mass in adolescent male athletes and nonathletes: relationships with high-impact sports. J Strength Cond Res 25(12): 3439-3447, 2011-This study examined the relationships between the practice of different categories of sports (high-impact vs. nonimpact) and bone status in adolescent male athletes and investigated differences from an age-matched control group. A total of 54 adolescent male athletes and 26 adolescent nonathletes were evaluated. Bone mineral density, bone mineral content (BMC), and bone area at the whole-body, limbs, and lumbar spine were determined by dual-energy x-ray absorptiometry, along with total and regional fat-free mass and body fat. The high-impact group included 34 athletes: 9 gymnasts, 18 basketball players, and 7 handball players (age: 15.7 ± 1.6 years; weight: 72.0 ± 15.0 kg; height: 178.5 ± 12.5 cm). The nonimpact group consisted of 20 swimmers (age: 16.4 ± 2.5 years; weight: 66.9 ± 10.4 kg; height: 173.7 ± 10.9 cm). The nonathletic control group included 26 male adolescents (age: 15.9 ± 2.8 years; weight: 64.7 ± 16.3 kg; height: 168.6 ± 15.1 cm). No differences were observed between the nonimpact and the control group in all bone variables, before and after adjustments for maturation level, body weight, and height (p > 0.05). After adjustments for these variables, the high-impact group displayed greater bone mass in most of the measured sites when compared to the other 2 groups (p < 0.001). Subjects in the nonimpact group showed lower values of BMC, particularly in the lower limbs, than both the high-impact and the nonathletic control groups (p < 0.05) after adjustments for maturation, high, and fat-free mass. This study reinforces the positive associations between high-impact physical activities and skeletal health in adolescent boys.     

The use of bacillary tuberculosis information system central files for special-purpose data search

The automated information system for surveillance of bacillary tuberculosis (ISBT) was put into operation in 1981, with the objective to record, store and process all mycobacterial positivity data reported by the network of specialized mycobacteriological laboratories in the Czech socialist republic. Here are described the newly developed data processing programs which allow it to carry out some special-purpose searches for the stored epidemiological data important for surveillance of tuberculosis. Further improvement of the national system of tuberculosis surveillance is believed to lie in the future compatibility of the two computerized systems operating at present in Czechoslovakia, i.e. ISBT and the Register of Tuberculosis.     

Longitudinal variation in food sources and their use by aquatic fauna along a subtropical river in Taiwan

1. River food webs rely on two major food sources: autochthonous primary production within the river and allochthonous organic matter transferred to the river. We characterised the consumer communities and assessed the food sources of dominant consumers along a subtropical mountainous river (the Lanyang River of north‐eastern Taiwan) at the catchment scale from the headwater to the estuary using natural abundances of stable carbon and nitrogen isotopes. 2. The downstream transport of fine particulate organic matter (FPOM) was two orders of magnitude greater than that of coarse particulate organic matter (CPOM). Transport of both materials increased from the headwater and reached a maximum in the midstream reach. CPOM composition exhibited a gradual shift from leaves and branches in the headwater, an area characterised by high canopy cover, to algae in the midstream reaches and marsh plants in the downstream reaches. 3. Consumer communities can be classified into two regional categories: the upland category in the headwater and upstream and midstream reaches and the lowland category comprised of samples from the downstream reach and estuary. The upland category revealed a clear and gradual seasonal shift in community composition, but a seasonal shift was not apparent for the lowland category. Nutrient concentrations and water temperature were the main factors explaining longitudinal and seasonal variations. 4. The use of sources of organic matter by dominant consumers along the Lanyang River was primarily determined by their availability. Riparian C₃ plants were the major food sources in the headwater, upstream reach and estuary, but the contribution of periphyton increased in the upper midstream reach where the river flows through an agricultural area. In the lower midstream and downstream reaches, the contribution of riparian C₄ plants became dominant. 5. The trophic transfer of organic materials in the Lanyang River may be influenced by the fast current velocity and by sewage nutrient loading in the river, both of which have important implications for predicting how the functioning of subtropical river food webs will respond to human‐related changes in land use.     

A case study of virilizing adrenal tumor in an adolescent female elite tennis player--insight into the use of anabolic steroids in young athletes

A 14-year-old Caucasian girl was referred to the endocrine clinic for evaluation of voice deepening, facial hirsutism, and acne starting 2 years previously. She had been a competitive tennis player since age 7 years, practicing for 4-6 hours daily. On physical examination she was noticed to have a masculine appearance with mild facial acne and moderate hirsutism. Tanner stage was 1 for breast tissue and 5 for pubic hair. Her androgen levels (testosterone, androstenedione, dehydroepiandrosterone sulfate) were extremely elevated. Adrenal ultrasonography revealed a round left 4.6 × 5.3-cm adrenal mass. Laparoscopic left adrenalectomy was performed. The histologic findings were compatible with a benign adrenocortical tumor. Postoperatively, androgen levels dropped to within the normal range. Breast development proceeded normally, menarche occurred 2 months after tumor resection, and menses has been regular since then. Muscle strength of the dominant and nondominant upper and lower extremities was measured 1 month before surgery and 1 year later, using an isokinetic dynamometer (Biodex Systems II, Biodex, Shirley, NY, USA). There was no significant decrease in overall muscle strength after removal of the virilizing tumor and the marked drop in circulating androgens. In addition, the patient maintained her age category, number 1, national tennis ranking. The results suggest that even extremely high levels of tumor-related circulating androgens had no evident effect on muscle strength and competitive performance in a female adolescent tennis player. The lack of beneficial effect on performance in adolescents, combined with the potentially hazardous side effects of anabolic steroids, suggests that teenage athletes should avoid their use.     

Possible sources of new information in the magnetocardiogram

The theoretical basis for the relationship between the electric and magnetic fields of the heart is examined in terms of impressed currents, J^j, from a biologically active region imbedded in an Ohmic conductor. For quasistatic sources in a uniform conductor, it is shown that the problem of measuring the electrocardiogram or magnetocardiogram is an inverse problem rendered non-unique by the presence of so-called silent sources. An important class of sources, toroidal J^j, are silent electrically and not silent magnetically and these sources result in inherent differences between the information content of the electric and magnetic measurement techniques. A hypothetical example of cardiac activation departing from the conventional uniform double-layer model is presented to indicate that electrically silent sources cannot be ruled out a priori without careful magnetic measurements.     

Association between sleep quality and pain in the cervical region and scapular waist in adolescent athletes

Sleep and Biological Rhythms - The objective of this study was to identify the prevalence of poor sleep quality and assess its association with pain in the cervical and scapular waist in amateur...     

Immobilization of Candida bombicola cells on free-standing organic-gold nanoparticle membranes and their use as enzyme sources in biotransformations

Preparation of chemically functionalized biocompatible surfaces is of current interest, with application in the immobilization of various bioactive species such as DNA, enzymes, whole cells, etc. We report herein the one-step synthesis of a self-supporting gold nanoparticle membrane, its surface modification, and application in the immobilization of Candida bombicola (yeast) cells. The gold nanoparticle membrane is prepared by the spontaneous reduction of aqueous chloroaurate ions by a diamine at a liquid-liquid interface. The gold nanoparticles in the polymeric membrane may be capped with octadecylamine (ODA) molecules, thereby rendering the nanoparticle membrane hydrophobic. Exposure of the hydrophobized organic-gold nanoparticle membrane to C. bombicola yeast cells results in their binding to the membrane, possibly through nonspecific interactions such as hydrophobic interactions between the yeast cell walls and the ODA molecules. The enzyme cytochrome P450 present in the yeast cells immobilized on the organic-gold nanoparticle membrane was then used in the transformation of the arachidonic acid (AA) to sophorolipids followed by acid hydrolysis to form 20-hydroxyeicosatetraneoic acid (20-HETE). The organic-gold nanoparticle membrane-C. bombicola bioconjugate could be easily separated from the reaction medium and reused a number of times.     

Dietary breadth of frugivorous birds in relation to their feeding strategies in the lowland forests of central Honshu,Japan

Variation in the dietary breadth of frugivorous birds, i.e. variation in the degree of dietary specialization, is a key factor for understanding the construction of the architecture of diffused fruit–bird interactions. However, little information is available on the dietary breadth of frugivorous birds in a community and the avian attributes influencing it. In this study, we evaluated and compared the dietary breadth of 23 frugivorous birds (including both seed dispersers and seed predators) in relation to their feeding strategies (depending on which the birds were categorized into four types as gulpers, grinders, crushers and peckers) and other avian attributes. In particular, we hypothesized that feeding types with long fruit‐handling time (i.e. crushers and peckers) have a narrow dietary breadth. Our analysis was based on the data obtained through long‐term volunteer monitoring in the lowland forests of Kanagawa prefecture, Japan. We evaluated the dietary breadth of the birds while controlling for differences in sampling efforts and seasonal variation in the available fruit assemblages among the birds. Our analysis revealed that there was a large variation in dietary breadth among the birds, even after controlling for differences in sampling efforts and seasonal variation in the available fruit assemblages. Feeding strategies of the birds defined their dietary breadth to some degree, but we found little support for the hypothesis that fruit handling determines dietary breadth. We also observed a large variation in dietary breadth among the gulpers, which act mainly as seed dispersers for plants, and this variation could not be explained fully by other avian attributes. Our results showed that variation in the dietary breadth of frugivorous birds is partly determined by their feeding strategies and suggested that other unknown factors may play a role in determining dietary breadth variation and in structuring fruit–bird interaction networks.