Iron status of female collegiate athletes involved in different sports

Iron status was assessed in 70 female athletes aged 18–25 yr participating in collegiate cross-country track, tennis, softball, swimming, soccer, basketball, and gymnastics. No significant differences in mean hemoglobin, hematocrit, serum iron, total iron-binding capacity, transferrin saturation, and ferritin were found among teams. The mean concentrations of each parameter for each of the teams were within the normal ranges. However, several athletes from different sports had suboptimal iron status indexes. Of 17 athletes with a serum ferritin concentration ≤15 μg/L, 8 (4 freshmen, 2 sophomores, 2 unknown) also exhibited low serum iron concentrations (< 60μg/dL) and low transferrin saturation (< 16%). Thirteen (6 freshmen, 3 sophomores, 2 juniors, 2 seniors) of 51 (25%) athletes failed to consume two-thirds of the Recommended Dietary Allowance for iron and exhibited suboptimal serum concentrations of ferritin, iron, and/or transferrin saturation. Of nine athletes taking iron supplements, one exhibited suboptimal iron status. In summary, nonanemic iron depletion was present among female collegiate athletes involved in many different sports and in all years of participation (freshmen, sophomore, junior, and senior athletes). Female athletes should continue to be individually and routinely evaluated for nutritional deficiencies throughout their collegiate athletic careers.     

Developmental plasticity varied with sex and position in hatching hierarchy in nestlings of the asynchronous European roller,Coracias garrulus

Allocation rules between ornamental and other functional traits of birds may differ among individuals and vary with environmental conditions. We supplemented roller (Coracias garrulus) nestlings with methionine in a between‐nest design to investigate the way in which the sex and position in the hatching hierarchy affect the allocation of resources among growth, immunity, and plumage coloration. Methionine induces the production of lymphocytes at expense of growth; thus, we used it to manipulate growth and immunity, which are two traits likely to compromise plumage coloration. We predicted that late‐hatched chicks within a brood (juniors) compared to early‐hatched chicks (seniors) should allocate more to traits directly providing fitness than to ornamental traits because juniors are more affected than seniors by sibling competition. The methionine treatment effectively enhanced the production of lymphocytes in experimental broods. This appeared to be at the expense of plumage coloration in junior nestlings because, in supplemented nests, junior males showed a trend to display less greenish bellies than junior males from control nests. However, juniors from supplemented nests maintained wing growth as in control juniors. The plumage coloration of seniors was unaffected by the methionine supplementation, although they paid the costs of lymphocyte production at a level of growth that was reduced compared to senior nestlings in control nests. Hence, sex, and hatching order affected resource allocation among growth, immunity, and plumage coloration of roller nestlings. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 99 , 500–511.     

Anthropometric and strength correlates of fast bowling speed in junior and senior cricketers

The aim of this study was to characterize relationships between anthropometric and isoinertial strength characteristics and bowling speed in junior and senior cricket fast bowlers. Subjects were first-class senior (n = 24; mean +/- SD age = 23.9 +/- 4.8 years, height = 187.4 +/- 4.8 cm, mass = 87.8 +/- 8.4 kg) and junior representative (n = 48; mean +/- SD age = 14.8 +/- 1.3 years, height = 175.7 +/- 9.8 cm, mass = 65.8 +/- 12.9 kg) male fast bowlers. A full anthropometric profile, upper- and lower-body isoinertial strength tests, and peak bowling speed (Vpeak) were assessed on the same day. The senior bowlers had a substantially faster Vpeak (126.7 km.h(-1)) than the juniors (99.6 km.h(-1)), a larger estimated muscle mass (seniors 40.0 +/- 3.9 kg, juniors 28.3 +/- 5.6 kg), and a greater bench press throw and deltoid throw (all p < 0.01). The best multiple predictors of Vpeak for the junior bowlers were the static jump, bench throw, body mass, percentage muscle mass, and height (multiple-correlation r = 0.86). For the senior bowlers, static jump and arm length correlated positively with Vpeak (multiple-correlation r = 0.74). The 1-legged countermovement jump was negatively correlated with Vpeak in both groups. We conclude that differences in Vpeak between junior and senior bowlers relate primarily to body mass and upper-body strength. However, lower body strength is a more important contributor to Vpeak in senior bowlers.     

The vigilance components of begging and sibling competition

The conflict between siblings over how parental resources are divided has promoted the evolution of specific behaviour to outcompete each other. Young animals look out for parents’ arrival in order to start begging as quickly as possible, since a rapid begging reaction increases the likelihood of being fed before nestmates. If the young can physically intercept the parents, selection might be operating on the offspring ability to monitor parent arrival (vigilance towards parents) and any sudden modifications in siblings’ behaviour (vigilance towards siblings). To investigate the adaptive value of nestling vigilance in the context of family interactions, we recorded which direction barn owl Tyto alba siblings were facing in 89 two‐chick broods before the first parental feeding visit of the night. Nestlings were more vigilant towards nest entrance than expected by chance suggesting that vigilance towards parents is an important component of sibling competition. When positioned near the nest‐box entrance where parents predictably deliver food, the younger individual (i.e. junior) looked more towards the entrance than its older sibling. Thus, when the likelihood of obtaining a food item is relatively high, juniors are more vigilant than seniors to detect the incoming parent. When positioned at the back of the nest, the senior looked relatively more frequently towards its sibling than the junior did in the same situation. This suggests that when the likelihood of obtaining a food item is relatively low, seniors are more vigilant than juniors to observe their sibling. Because vigilance was not related to hunger level and prey obtaining, we propose the hypothesis that vigilance towards parents and siblings only indirectly influences the outcome of sibling competition.     

Costs of growing up as a subordinate sibling are passed to the next generation in blue‐footed boobies

As stresses in early development may generate costs in adult life, sibling competition and conflict in infancy are expected to diminish the reproductive value of surviving low‐status members of broods and litters. We analysed delayed costs to blue‐footed booby fledglings, Sula nebouxii, of junior status in the brood, which involves aggressive subordination, food deprivation and elevated corticosterone, but little or no deficit in size at fledging. In ten cohorts observed for up to 16 years, juniors showed no deficit in breeding success at any age, independent of lifespan, including in a sample of sibling pairs. Among females, juniors actually outreproduced seniors across the 16‐year span. However, offspring produced by juniors in the first 3 years of life were less likely to recruit into the breeding population than offspring of seniors. Since junior fledglings survive, recruit and compete as well as seniors (shown earlier), and breed as successfully as seniors across the lifespan, it appears the delayed cost of subordination is passed to offspring, and only to those few offspring produced in the first 3 years of life. These correlational results indicate that systematic competition‐related differences in developmental conditions of infant siblings can alter their reproductive value by affecting the viability of their eventual offspring.     

Performance changes following a field conditioning program in junior and senior rugby league players

This study investigated training loads, injury rates, and physical performance changes associated with a field conditioning program in junior and senior rugby league players. Thirty-six junior (16.9 [95% confidence interval: 16.7-17.1] years) and 41 senior (25.5 [23.6- 27.3] years) rugby league players participated in a 14-week preseason training program that included 2 field training sessions each week. Subjects performed measurements of standard anthropometry (height, body mass, and sum of 7 skinfolds), muscular power (vertical jump), speed (10-, 20-, and 40-m sprint), agility (L run), and maximal aerobic power (multistage fitness test) before and after training. Improvements in agility, muscular power, and maximal aerobic power were observed in both the junior and senior players following training; however, the improvement in maximal aerobic power and muscular power were greatest in the junior players. Training loads and injury rates were higher in the senior players. These findings demonstrate that junior and senior rugby league players adapt differently to a given training stimulus and that training programs should be modified to accommodate differences in training age.     

Set of criteria for the actual quality evaluation of the elite basketball players

The paper comprises a proposition of nineteen criteria for the actual quality (situation-related efficiency/performance) evaluation in the elite basketball players (seven criteria for the efficiency on defence and twelve for the efficiency on offence) regarding all the playing positions. Coaches and other practitioners connected to the domain of basketball could utilize this set of criteria for the individual and team aspects of the performance follow-up and assessment in players throughout their sports career, from the cadettes' to the senior selections. Proposed set of criteria is the pressumption for the exact scientific and expert approach to the basketball performance (situation-related efficiency) evaluation and prediction--criterion variable. Weighting factors (coefficients of significance) for each criterion in relation to the playing positions should be determined on the next stage of developing a system of the performance evaluation criteria.     

Food limitation in asynchronous bluethroat broods: effects on food distribution, nestling begging, and parental provisioning rules

Scramble competition models of begging predict that junior nestlingswill be more affected by food limitation than seniors. Thesemodels assume that food allocation is under offspring controland, hence, predict that this change in food distribution iscaused by a differential behavioral response by seniors andjuniors. By using the bluethroat (Luscinia svecica svecica)as our model species, we induced food limitation by removingthe male parent temporarily. We found that, as predicted, fooddistribution became more biased in disfavor of juniors whenfood was limited. However, there was no significant differencein the behavioral responses of seniors and juniors (i.e., positioningin the nest or begging postures) to food limitation that couldexplain the change in food distribution. Hence, there was noevidence that seniors controlled food distribution. As predictedif parents preferentially fed seniors, nestling rank affectedfood distribution when controlling for variation in nestlingbehaviors. Furthermore, as expected if the increased skew infood distribution under food limitation was caused by activefood allocation by parents, nestling rank had a greater effecton food distribution under food limitation than under normalconditions. The present study suggests that food distributionin passerine birds is determined not only by nestling behaviors(begging posture and positioning) alone but also by parentalpreferences for seniors based on nonsignaling cues, such asbody size.     

Injuries in racket sports among Slovenian players

On the sample of 83 top Slovenian athletes we have studied the frequency of injuries among table tennis, tennis and badminton players, types of injuries and severity of injuries--the latter based on data of players absences from training and/or competition processes. The most liable parts to injuries are shoulder girdle (17.27%), spine (16.55%) and ankle (15.83%), while foot (10.07%) and wrist (12.23%) are slightly less liable to injuries. The most frequent injuries in racket sports pertain to muscle tissues. According to this data, the majority of injuries occur halfway through a training session or a competition event, mostly during a competition season. The injuries primarily pertain to muscle tissues; these are followed by joint and tendon injuries. There are no differences between male and female players. Compared to other racket sports players, table tennis players suffer from fewer injuries.     

Differences in conative characteristics and perceived group cohesion of the basketball players playing in different positions in the team

Identification of differences in individual conative characteristics and in perceived group cohesion of the basketball players playing in different positions in the team could provide guidelines for a better selection of basketball players and better coaching work. The aim of our study was to determine the differences in relation to the positions of guards and forwards/centres, and the four major positions in the team. The final sample of subjects (74 basketball players) is selected from the initial sample of 107 subjects, selected from nine men's senior basketball teams that played in A-1 Croatian men's basketball league championship in 2006/2007. The results showed no statistically significant difference between basketball players who play in different positions in the team, neither in relation to two basic positions in the team (guards as opposed to forwards/centres), nor in relation to the four positions in the team (point guard, shooting guard, small forward, power forward/centre).     

The yo-yo intermittent recovery test in junior basketball players according to performance level and age group

The aim of this study was to evaluate the Yo-Yo Intermittent Recovery Test Level 1 (Yo-Yo IR1) ability to discriminate between elite, subelite junior basketball players, and a group of nonathletic healthy male athletes at 3 different age groups (U-14 to U-17). In a cross-sectional design, 119 age-matched participants spread over 3 groups, elite (n = 46), subelite (n = 42) junior basketball players, and nonathletic healthy male athletes (n = 31), were evaluated over a 5-week period. The participants undertook 2 familiarization trials of the Yo-Yo test performance and 3 test sessions on an indoor basketball court. When controlling for the effect of the participants' body mass, the results showed that elite athletes had a significantly higher Yo-Yo performance compared with the subelite athletes (1,271 ± 385 vs. 861 ± 428 m; p < 0.0017; effect size [ES] 1.0 ± 0.35) and the nonathletic group (1,271 ± 385 vs. 738 ± 345 m; p < 0.0017; ES 1.45 ± 0.38). No statistical differences (p > 0.0017; ES from 0.02 to 0.39) were noted between participants' performance levels across age groups. Typical between-performance levels and -age groups differences in the Yo-Yo IR1 were observed. However, when controlling for the effect of the participants' body mass, this study demonstrates that the Yo-Yo test is accurate only to discriminate elite junior basketball players but cannot be used to differentiate the basketball-specific aerobic performance for age.     

Influence of field size on the physiological and skill demands of small-sided games in junior and senior rugby league players

The purpose of this study was to investigate the effect of changes in field size on the physiological and skill demands of small-sided games in elite junior and senior rugby league players. Sixteen elite senior rugby league players ([mean ± SE] age, 23.6 ± 0.5 years) and 16 elite junior rugby league players ([mean ± SE] age, 17.3 ± 0.3 years) participated in this study. On day 1, 2 teams played an 8-minute small-sided game on a small field (10-m width × 40-m length), whereas the remaining 2 teams played the small-sided game on a larger sized field (40-m width × 70-m length). On day 2, the groups were crossed over. Movement was recorded by a global positioning system unit sampling at 5 Hz. Games were filmed to count the number of possessions and the number and quality of disposals. The games played on a larger field resulted in a greater (p < 0.05) total distance covered, and distances covered in moderate, high, and very-high velocity movement intensities. Senior players covered more distance at moderate, high, and very-high intensities, and less distance at low and very-low intensities during small-sided games than junior players. Although increasing field size had no significant influence (p > 0.05) over the duration of recovery periods for junior players, larger field size significantly reduced (p < 0.05) the amount of short-, moderate-, and long-duration recovery periods in senior players. No significant between-group differences (p > 0.05) were detected for games played on a small or large field for the number or quality of skill involvements. These results suggest that increases in field size serve to increase the physiological demands of small-sided games but have minimal influence over the volume or quality of skill executions in elite rugby league players.     

Relation between maximal aerobic power and the ability to repeat sprints in young basketball players

The aim of this study was to examine the effects of maximal aerobic power (V(.-)O2max peak) level on the ability to repeat sprints (calculated as performance decrement and total sprinting time) in young basketball players. Subjects were 18 junior, well-trained basketball players (age, 16.8 +/- 1.2 years; height, 181.3 +/- 5.7 cm; body mass, 73 +/- 10 kg; V(.-)O2max peak, 59.6 +/- 6.9 ml x kg(-1) x min(-1)). Match analysis and time-motion analysis of competitive basketball games was used to devise a basketball-specific repeated-sprint ability protocol consisting of ten 15-m shuttle run sprints with 30 s of passive recovery. Pre, post, and post plus 3-minute blood lactate concentrations were 2.5 +/- 0.7, 13.6 +/- 3.1, and 14.2 +/- 3.5 mmol x L(-1), respectively. The mean fatigue index (FI) value was 3.4 +/- 2.3% (range, 1.1-9.1%). No significant correlations were found between V(.-)O2max peak and either FI or total sprint time. A negative correlation (r = -0.75, p = 0.01) was found between first-sprint time and FI. The results of this study showed that V(.-)O2max peak is not a predictor of repeated-sprint ability in young basketball players. The high blood lactate concentrations found at the end of the repeated-sprint ability protocol suggest its use for building lactate tolerance in conditioned basketball players.     

Retrospective case evaluation of gender differences in sports injuries in a Japanese sports medicine clinic

Background: Although both gender- and sports-specific injuries exist among athletes, gender differences in the types of injuries caused by sports activities, except for anterior cruciate ligament (ACL) injury and anterior knee pain, are not well established.Objective: An observational study with a retrospective case-series design was conducted to investigate gender-specific differences in the types of injuries sustained while engaging in sports activities common to both males and females.Methods: We analyzed injuries sustained during sports activities including basketball, volleyball, tennis, skiing, track and field, and swimming, using data on age, sex, sports activities, activity levels, and sports injuries that had been computerized at our sports medicine (orthopedics) clinic. Inclusion criteria were sports activities that had a record of >100 injuries in total and athletes aged <50 years who were engaging in only 1 sports activity. We determined the absolute number of patients in each category and their percentage (proportion) of our cohort. The proportions of common injuries caused by sports activities were investigated, and gender-specific differences in the types of common injuries caused by sports activities were clarified. The Fisher exact test was used to determine the significance (P < 0.01) of the gender-specific differences in the types of sports injuries.Results: According to our database, during the 14-year period between October 1992 and December 2006, a total of 2989 athletes (1624 males and 1365 females) aged <50 years who engaged in 1 of the 6 sports activities described consulted our sports medicine clinic. The most common sports injuries were ACL injury (14.3%) and knee pain (13.7%), followed by ankle sprain (9.4%), lumbar disc disease (7.0%), meniscus injury (5.1%), stress fracture (2.9%), low back pain (2.5%), patellar tendinitis (2.1%), injury of the medial collateral ligament of the knee (2.0%), lumbar spondylolysis (1.7%), and muscle strain (1.5%). Among these 11 types of sports injuries, a significantly higher proportion of females who engaged in basketball (24.4% vs 10.5%), volleyball (20.5% vs 4.5%), or skiing (41.4% vs 26.5%) presented with an ACL injury, compared with their male counterparts (all, P < 0.001). There was also a significantly higher proportion of females than of males among the track and field athletes who presented with stress fractures (18.7% vs 3.9%; P < 0.001).Conclusion: The findings of this retrospective study suggest that there are gender-specific differences in the types of injuries sustained during sports activities.     

Parental Distribution of Resources in Relation to Larval Hunger and Size Rank in the Burying Beetle Nicrophorus vespilloides

In altricial birds, the parents' distribution of resources within the brood is influenced by variation in at least two components of nestling condition: hunger level and size rank. Here, we examine whether variation in larval hunger and size rank had similar influences on the parents' distribution of resources in the burying beetle Nicrophorus vespilloides . To this end, we analyzed hitherto unpublished data on parental resource distribution among individual larvae derived from three previous experiments. Our first experiment showed that resource distribution was biased towards hungry larvae at the expense of control larvae, but that actively begging hungry larvae were as likely to obtain resources from parents as actively begging control larvae. Thus, resource distribution was biased towards hungry larvae because hungry larvae spent more time begging than control larvae. Our second experiment showed that actively begging senior larvae (i.e. larvae that were older and larger) were more likely to obtain resources than actively begging junior larvae, suggesting that senior larvae had a competitive advantage or were treated preferentially by the parents. Our third experiment found no evidence that the interaction between larval hunger and size rank had an effect on parental resource distribution, suggesting that hunger level had a similar effect on resource distribution to seniors and juniors. We conclude that offspring hunger and size rank have remarkably similar effects in the burying beetle N. vespilloides as reported in studies on altricial birds.     

Differences in situation efficacy indicators at the elite basketball players that play on different positions in the team

The aim of our study was to determine the differences in situational efficacy for basketball players, in relation to their team positions: between guards and forwards/centres, and between the players on the four major positions in the team. The final sample of subjects (74 basketball players) is selected from the initial sample of 107 subjects, selected from nine men's senior basketball teams that played in A-1 Croatian men's basketball league championship in 2006/2007. Results confirmed the hypothesis that there is a significant difference between different groups of players: point/shooting guards, comparing with forwards/centres; players that play on four positions: point guard, shooting guard, small forward, power forward/centre. Guards have shown greater efficiency and utilization of the three-point shots, while centres are better in two-point shots. Guards have a greater number of assists, successful and unsuccessful three-point shots, while centres are better in the offensive and defensive rebounds, as same as in successful and unsuccessful two-point shots. No statistically significant differences were found among the players on the guard positions (point guard and shooting guard), while only one statistically significant difference is found among the players on the position forward/centre (small forward and power forward/centre).     

Hormonal Correlates of Dominance and Starvation-induced Aggression in Chicks of the Blue-footed Booby

In the blue-footed booby (Sula nebouxii), the first-hatched chick aggressively dominates its sibling and sometimes kills it when food is in short supply. To investigate the endocrine correlates of dominance-subordinance and hunger-induced agonism, we deprived 15–20-d-old single-chick and two-chick broods of food during 48 h by taping chicks' necks to prevent ingestion of parentally provided food (a protocol used previously and known to elicit escalated sibling fighting). We monitored weight and levels of circulating testosterone, oestradiol and corticosterone in deprived and normally fed broods comprising singletons, seniors (= dominants) and juniors (= subordinates), and observed behaviour to verify that aggression increased in deprived two-chick broods. During the 2 d of fasting, experimental chicks lost on average 6% of their baseline weight. After normal feeding was reinstated, seniors and singletons recovered normal (control) weight, but juniors remained significantly lighter than controls. No testosterone was detected in any nestling, but baseline corticosterone level was 109% higher in juniors than in seniors or singletons, implying that elevated corticosterone in juniors is a consequence of social subordination and may facilitate submissive behaviour. Although there was evidence that aggression of seniors increased under food deprivation, the increase was not accompanied by the rise in levels of testosterone expected under the ‘Challenge hypothesis’ (Wingfield et al. 1990). This result implies that this hypothesis probably does not apply to booby nestlings in the context of starvation-induced aggression. During the 2 d deprivation period, corticosterone levels of experimental chicks increased significantly, then declined to baseline levels a day after tapes were removed. The increase was probably due to the combined effects of starvation and frustration. We suggest that corticosterone could alter responsiveness of nestling blue-footed boobies to external stimuli, resulting in more aggression by dominants and greater readiness of subordinates to submit.     

Exercises to prevent lower limb injuries in youth sports: cluster randomised controlled trial

Objective To investigate the effect of a structured warm-up programme designed to reduce the incidence of knee and ankle injuries in young people participating in sports.Design Cluster randomised controlled trial with clubs as the unit of randomisation.Setting 120 team handball clubs from central and eastern Norway (61 clubs in the intervention group, 59 in the control group) followed for one league season (eight months).Participants 1837 players aged 15-17 years; 958 players (808 female and 150 male) in the intervention group; 879 players (778 female and 101 male) in the control group.Intervention A structured warm-up programme to improve running, cutting, and landing technique as well as neuromuscular control, balance, and strength.Main outcome measure The rate of acute injuries to the knee or ankle.Results During the season, 129 acute knee or ankle injuries occurred, 81 injuries in the control group (0.9 (SE 0.09) injuries per 1000 player hours; 0.3 (SE 0.17) in training v 5.3 (SE 0.06) during matches) and 48 injuries in the intervention group (0.5 (SE 0.11) injuries per 1000 player hours; 0.2 (SE 0.18) in training v 2.5 (SE 0.06) during matches). Fewer injured players were in the intervention group than in the control group (46 (4.8%) v (76 (8.6%); relative risk intervention group v control group 0.53, 95% confidence interval 0.35 to 0.81).Conclusion A structured programme of warm-up exercises can prevent knee and ankle injuries in young people playing sports. Preventive training should therefore be introduced as an integral part of youth sports programmes.     

Alterations to movement mechanics can greatly reduce anterior cruciate ligament loading without reducing performance

Anterior cruciate ligament (ACL) injuries are one of the most common and potentially debilitating sports injuries. Approximately 70% of ACL injuries occur without contact and are believed to be preventable. Jump stop movements are associated with many non-contact ACL injuries. It was hypothesized that an athlete performing a jump stop movement can reduce their peak tibial shear force (PTSF), a measure of ACL loading, without compromising performance, by modifying their knee flexion angle, shank angle, and foot contact location during landing. PTSF was calculated for fourteen female basketball players performing jump stops using their normal mechanics and mechanics modified to increase their knee flexion angle, decrease their shank angle relative to vertical and land more on their toes during landing. Every subject tested experienced drastic reductions in their PTSF (average reduction=56.4%) using modified movement mechanics. The athletes maintained or improved their jump height with the modified movement mechanics (an average increase in jump height of 2.5 cm). The hypothesis was supported: modifications to jump stop movement mechanics greatly reduced PTSF and therefore ACL loading without compromising performance. The results from this study identify crucial biomechanical quantities that athletes can easily modify to reduce ACL loading and therefore should be targeted in any physical activity training programs designed to reduce non-contact ACL injuries.