D.M. Peters

Crossvalidation of Anthropometry Against Magnetic Resonance Imaging for the Assessment of Visceral and Subcutaneous Adipose Tissue in Children

Background:The study of the relationship between anthropometry and visceral adipose tissue (VAT) is of great interest because VAT is associated with many risk factors for noncommunicable diseases and anthropometry is easy to perform in clinical practice. The studies hitherto available for children have, however, been performed on small sample sizes.Design:Pooling of the data of studies published from 1992 to 2004 as indexed on Medline.Aims:To assess the relationship between anthropometry and VAT and subcutaneous adipose tissue (SAT) as measured by magnetic resonance imaging (MRI) in children and to analyze the effect of age, gender, pubertal status and ethnicity.Subjects and methods:Eligible subjects were 7–16 year-old, with availability of VAT and SAT, gender, ethnicity, body mass index (BMI) and waist circumference (WC). A total of 497 subjects were collected from seven different investigators and 407 of them (178 Caucasians and 229 Hispanics) were analyzed.Results:Despite ethnic differences in MRI data, BMI, WC and age, no difference in VAT was found between Caucasians and Hispanics after correction for SAT and BMI. Univariate regression analysis identified WC as the best single predictor of VAT (64.8% of variance) and BMI of SAT (88.9% of variance). The contribution of ethnicity and gender to the unexplained variance of the VAT–WC relationship was low (⩽3%) but significant (P⩽0.002). The different laboratories explained a low (⩽4.8%) but significant (P<0.0001) portion of the unexplained variance of the VAT–WC and SAT–BMI relationships. Prediction equations for VAT (VAT (cm2)=1.1 × WC (cm)−52.9) and SAT (SAT (cm2)=23.2 × BMI (kg/m2)−329) were developed on a randomly chosen half of the population and crossvalidated in the remaining half. The pure error of the estimate was 13 cm2 for VAT and 57 cm2 for SAT.Conclusions:WC can be considered a good predictor of VAT as well as BMI of SAT. The importance of ethnicity and gender on VAT estimation is not negligible.

Seasonal Variation in Physiological Fitness of a Semiprofessional Soccer Team

Caldwell, BP and Peters, DM. Seasonal variation in physiological fitness of a semiprofessional soccer team. J Strength Cond Res 23(5): 1370-1377, 2009-The purpose of this study was to investigate seasonal variations in physiological fitness of semiprofessional soccer players over a 12-month period. Thirteen male players were tested 5 times over a 12-month period using bioelectrical impedance, a 20-m multistage fitness test, countermovement standing vertical jump, 15-m sprint test, Illinois agility test, and sit and reach test. Significant deconditioning was apparent in all fitness variables from end of season one season to prepreseason training of the next season. Aerobic fitness, vertical jump, percent body fat, agility, and sprint performance improved from prepreseason to midseason. Significant decreases in aerobic fitness and the cessation of significant increases in vertical jump, sprint, and agility performance were shown from midseason onward. No differences between the fitness components at the end of season one and the end of season two were identified. The deconditioning apparent in all fitness parameters during the off season, together with progressive improvement in most from postpreseason to midseason would support these parameters as sport-specific fitness requirements. Such improvements suggest that the short-term demands of playing and training in the first half of the season develop fitness and these trends are similar to those for professional players. Body fat was also shown to be detrimental to sprint performance throughout the 12-month period. Further research is needed to identify if the plateau in fitness from midseason is the result of attaining the required level of fitness, fatigue, allied training, or even relative success. Enhancing off-season training may enable yearly fitness increases by at least maintaining fitness levels for the next years preseason.

Magnetic resonance imaging of abdominal adiposity in a large cohort of British children

Objective:To describe abdominal adipose tissue distribution in a large sample of contemporary British children; to determine the influence of gender, stage of maturation and body mass index (BMI) on abdominal adipose tissue distribution; and to compare the ability of BMI and waist circumference to predict abdominal adipose tissue.Subjects and methods:A total of 74 boys (mean age 13.4±0.4 years) and 96 girls (mean age 13.5±0.5 years) were selected from volunteer children enrolled in the Avon Longitudinal Study of Parents and Children (ALSPAC). Height, weight and waist circumference were measured and BMI calculated. Stage of sexual maturation was available for 113 children using a self-report questionnaire based on Tanners criteria. Magnetic resonance imaging was used to assess subcutaneous abdominal adipose tissue (SAAT) and intra-abdominal adipose tissue (IAAT) volumes and patterning.Results:Boys had lower levels of IAAT (P=0.036) and SAAT (P=0.003) than girls. IAAT and SAAT were higher in overweight and obese boys and girls when compared with normal weight children (P<0.0001). This pattern was also reflected in waist circumference groups. Boys had higher IAAT/SAAT ratios than girls, indicating proportionately more adipose tissue deposited intra-abdominally (P=0.002). However, both boys and girls deposited less than 10% of their abdominal fat as internal adipose tissue. WC predicted 67.4% of the variance in IAAT (P<0.001), and BMI predicted 84.8% of the variance in SAAT (P<0.001). However, BMI as the best single predictor explained only 8.4% of the variance in the IAAT/SAAT ratio (P<0.001).Conclusions:At this age and stage of sexual maturation, the amount of IAAT remains relatively small. WC and BMI offer a feasible alternative to the MRI estimation of IAAT and SAAT, respectively, in a population-based sample of boys and girls.

Assessment of abdominal fat development in young adolescents using magnetic resonance imaging.

OBJECTIVE: To determine the patterns of change and the best anthropometric indicators of intra-abdominal fat deposition in young adolescents from ages 11–13 y.SUBJECTS: Subjects were 25 boys (mean age 13.7±0.32 y) and 17 girls (mean age of 13.7±0.23 y) who had taken part in a similar study 2 y earlier at ages 11.5±0.33 y and 11.5±0.27 y, respectively.METHODS: Intra-abdominal (IA) and subcutaneous adipose (SA) tissue areas and IA/SA ratio were determined through four tranverse magnetic resonance imaging scans on two occasions. Differences were investigated using t-tests and ANOVA. Skinfolds, girths and circumferences, body mass index and hydrostatic weighing were also recorded. Pearson correlation coefficients and regression equations were calculated to determine the best anthropometric indicators of intra-abdominal fat deposition.RESULTS: Intra-abdominal fat and subcutaneous fat areas had significantly increased in boys and girls by the second measure. Boys had deposited greater amounts of fat in intra-abdominal depots so that their intra-abdominal/subcutaneous ratio had increased significantly from 0.31 to 0.39. This had reduced in girls from 0.39 to 0.35. However, patterns of change were variable within sexes. Truncal skinfold sites (r=0.54–0.70) emerged as the best field indicators of intra-abdominal fat deposition.CONCLUSIONS: Patterns of intra-abdominal and subcutaneous fat distribution are identifiable in pubescent children using magnetic resonance imaging. An acceptable indication is provided by truncal skinfolds.

Preferred Coach Leadership Behaviour in Elite Soccer in Relation to Success and Failure

Multidimensional models of leadership in sport suggest that in order to maximize performance there should be congruence between the actual coaching behaviour and behaviours preferred by players. This study examined the preferred coaching leadership behaviours in prolonged periods of perceived success and failure in eighty-eight elite soccer players in Norway using the Leadership Scale for Sport (LSS). The three preferred behaviours were Positive Feedback, Training & Instruction, and Democratic Behaviour in both scenarios. All preferred behaviours (except Autocratic Behaviour) were higher in the unsuccessful scenario (p <.01). Negative relationships existed between age/experience and Social Support, Democratic Behaviours and Positive Feedback in the successful scenario and between age/experience and Social Support and Democratic Behaviours in the unsuccessful scenario (p <.05). The findings therefore have implications for adapting coaching leadership behaviours when players of different ages and with different levels of experience encounter prolonged periods of success or failure.

Age and Grip Strength Predict Hand Dexterity in Adults.

In the scientific literature, there is much evidence of a relationship between age and dexterity, where increased age is related to slower, less nimble and less smooth, less coordinated and less controlled performances. While some suggest that the relationship is a direct consequence of reduced muscle strength associated to increased age, there is a lack of research that has systematically investigated the relationships between age, strength and hand dexterity. Therefore, the aim of this study was to examine the associations between age, grip strength and dexterity. 107 adults (range 18-93 years) completed a series of hand dexterity tasks (i.e. steadiness, line tracking, aiming, and tapping) and a test of maximal grip strength. We performed three phases of analyses. Firstly, we evaluated the simple relationships between pairs of variables; replicating the existing literature; and found significant relationships of increased age and reduced strength; increased age and reduced dexterity, and; reduced strength and reduced dexterity. Secondly, we used standard Multiple Regression (MR) models to determine which of the age and strength factors accounted for the greater variance in dexterity. The results showed that both age and strength made significant contributions to the data variance, but that age explained more of the variance in steadiness and line tracking dexterity, whereas strength explained more of the variance in aiming and tapping dexterity. In a third phase of analysis, we used MR analyses to show an interaction between age and strength on steadiness hand dexterity. Simple Slopes post-hoc analyses showed that the interaction was explained by the middle to older aged adults showing a relationship between reduced strength and reduced hand steadiness, whereas younger aged adults showed no relationship between strength and steadiness hand dexterity. The results are discussed in terms of how age and grip strength predict different types of hand dexterity in adults.

Discrepancies in accelerometer-measured physical activity in children due to cut-point non-equivalence and placement site

Abstract This study examined dissonance in physical activity (PA) between two youth-specific hip-derived intensity cut-points for the Actiwatch (AW), and compared PA between hip and wrist placements using site-specific cut-points. Twenty-four children aged 11.2 ± 0.5 years wore the AW on the right hip and non-dominant wrist during a typical school day. Minutes of sedentary behaviour and vigorous activity were greater using Puyau et al. (2002) cut-points, but light, moderate, and moderate-to-vigorous (MVPA) were greater when derived using Puyau et al. (2004) cut-points (P < 0.01). Total hip activity counts were lower than wrist. Sedentary minutes were greater at the hip, but minutes of light, vigorous and MVPA were lower (P < 0.01). Moderate minutes were greater at the hip, but differed only when applying the Puyau et al. (2004) cut-points (P < 0.01). In conclusion, data comparisons between two hip derived AW cut-points and between hip and wrist data are inappropriate. Future researchers using the AW at the hip should present data reduced using both published cut-points. As hip and wrist data differ, the wrist placement is preferable as it will likely increase childrens compliance to monitoring protocols due to reduced obtrusiveness compared to the hip.

Preferred ‘learning styles’ in students studying sports‐related programmes in higher education in the United Kingdom

This article investigates the ‘preferred learning styles’ and their relationship with grades for students undertaking sports‐related undergraduate programmes at a higher education institution in the UK. Preferred ‘learning styles’ in students in this discipline have been identified as auditory, kinaesthetic and group, although the vast majority of students are multimodal in their learning preferences. Only individual learning style preference was found to be positively related to higher grade category, and group learning style preference was negatively related to grade category. The research aims to highlight the importance of a constructive alignment between sports learning activities and the learning styles of sports students, in order to enhance progression towards established sports learning outcomes. An issue of significance for the practitioner would be rebalancing learning and teaching methods to take cognisance of particular preferred learning styles, while still seeking to ensure that all learning styles are supported.

Differences in axial segment reorientation during standing turns predict multiple falls in older adults

BACKGROUND The assessment of standing turning performance is proposed to predict fall risk in older adults. This study investigated differences in segmental coordination during a 360° standing turn task between older community-dwelling fallers and non-fallers. METHODS Thirty-five older adults age mean (SD) of 71 (5.4) years performed 360° standing turns. Head, trunk and pelvis position relative to the laboratory and each other were recorded using a Vicon motion analysis system. Fall incidence was monitored by monthly questionnaire over the following 12 months and used to identify non-faller, single faller and multiple faller groups. RESULTS Multiple fallers were found to have significantly different values, when compared to non-fallers, for pelvis onset (p=0.002); mean angular separation in the transverse plane between the head and trunk (p=0.018); peak angular separation in the transverse plane between the trunk and pelvis (p=0.013); and mean angular separation between the trunk and pelvis (p<0.001). CONCLUSIONS Older adults who subsequently experience multiple falls show a simplified turning pattern to assist in balance control. This may be a predictor for those at increased risk of falling.

A systematic review of physical fitness, physiological demands and biomechanical performance in equestrian athletes

This article presents a systematic review of the literature investigating physical fitness, physiological demands and biomechanical performance in equestrian athletes. Three databases (SportsDiscus, CAB abstracts and PubMed) were searched to identify the literature. The main search term of ‘horse-riding’ was combined with eleven specific keywords (‘fitness’, ‘physiology’, ‘biomechanics’, ‘equestrian’, ‘athlete’, ‘co-ordination’, ‘heart rate’, ‘oxygen consumption’ ‘kinematic’ ‘EMG’ and ‘skill’). Exclusion criteria were: conference proceedings, abstracts, theses, and non-peer reviewed articles. Subsequently, 15 peer-reviewed papers were identified and included within this review. The main research findings are that as a horse progresses through the gaits (walk, trot and canter), the riders heart rate and oxygen consumption increase. The causal physiological factor at present is thought to be higher levels of tonic muscular contraction particularly of the trunk, which in elite equestrians achieves a more controlled upright trunk position, compared to their novice counterparts. It is the faster gaits, and jumping that require the rider to adopt a ‘forwards’ riding position that necessitates weight bearing to be through the riders legs, as opposed to a seated position, where weight bearing is predominantly through the pelvis. It is apparent that these ‘forward position’ modes of riding significantly increase metabolic cost and result in elevated levels of blood lactate, thus implying that they incorporate some anaerobic demand. Due to the paucity of literature available for review and particularly that which incorporates data obtained from ‘competitive’ performances, future research should attempt to prioritise investigations in competitive in addition to simulated riding environments. Only when further physiological and biomechanical data are available from a greater range of equestrian disciplines and from a range of level of athletes, will the demands of these sports be more clearly understood. Until such time, the development of evidence-based sport specific and potentially performance enhancing rider strength and conditioning programmes cannot be realised.