BMI is dead; long live waist-circumference indices: But which index should we choose to predict cardio-metabolic risk?

BACKGROUND AND AIMS: There is growing evidence that Body Mass Index (BMI) is unfit for purpose. Waist circumference (WC) indices appear to be the preferred alternative, although it is not clear which WC index is optimal at predicting cardio-metabolic risk (CMR) and associated health outcomes. METHODS AND RESULTS: We obtained a stratified random probability sample of 53,390 participants from the Health Survey for England (HSE), 2008-2018. The four available CMR factors were; high-density lipoproteins (HDL) cholesterol, glycated haemoglobin (HbA1c), systolic (SBP) and diastolic blood pressure (DBP). Strength of association between the four cardio-metabolic risk factors and competing anthropometric indicators of weight status [BMI, Waist-to-height ratio (WHTR), unadjusted WC, and a new WC index independent of height, WHT·5R = WC/height0.5] was assessed separately, using simple correlations and ANCOVAs, and together (combined) using MANCOVA, controlling for age, sex and ethnicity. Centile curves for the new index WHT·5R = WC/height0.5were also provided. CONCLUSIONS: Waist-circumference indices were superior to BMI when explaining/predicting our CMR factors, before and after controlling for age, sex and ethnicity. No single WC index was consistently superior. Results suggest that WHTR is the strongest predictor of HbA1c, confirming that shorter individuals are at great risk of diabetes. The most appropriate WC index associated with blood pressure was WHT·5R for DBP, or unadjusted WC for SBP. Given HDL cholesterol is independent of height, the best predictor of HDL was WHT.5R. Clearly, "no one size fits all!". MANCOVA identified WHT·5R to be the best single WC index associated with a composite of all four CMR factors.

Common mental disorders among Irish jockeys: prevalence and risk factors.

OBJECTIVE: Jockeys compete in a sport, horseracing, renowned for its physical and psychological demands. Previous research has identified that common mental disorders (CMDs) may be prevalent among this unique population of athletes. The aim of the present study was to further explore the prevalence of CMDs among jockeys and to test for associations with potential risk factors. METHODS: An anonymous survey was distributed to professional jockey online. Self-report screening tools for four CMDs (psychological distress, depression, generalized anxiety, and adverse alcohol use) were included alongside predictor variables from questionnaires assessing for burnout, career satisfaction, social support, and the contemplation of retirement. Binary logistic regression was used to explore associations between CMDs (present versus not present) and risk factors. Eighty-four professional jockeys completed the questionnaire (response rate = 52%). RESULTS: In total, 79% of jockeys met the threshold for at least one CMD. Prevalence (%) of CMD varied as follows: adverse alcohol (61%), depression (35%), generalized anxiety (27%), and psychological distress (19%). Burnout, career (dis)satisfaction, lower levels of social support, and the contemplation of retirement increased the odds of meeting the criteria for CMDs. CONCLUSION: The findings indicate that jockeys report CMD symptoms at comparable rates to athletes in other sports. The study was the first to highlight potential risk factors as predictors of CMDs among jockeys, including burnout, career satisfaction, and the current contemplation of retirement. Screening tools for the risk factors demonstrated may, therefore, provide useful in the early identification of CMDs among jockeys. The development of jockey-specific assessment tools, education programmes, and interventions may help better understand and support the mental health of jockeys.

Modeling children's development in gross motor coordination reveals key modifiable determinants. An allometric approach.

Children change their body size, shape, and gross motor coordination (GMC) as they grow. Further, GMC is expected to link to changes in children's body size, physical activity (PA), and physical fitness (PF). The objective was to model GMC changes in children followed longitudinally and to investigate associations between these changes and PA and PF levels. A total of 245 children (122 girls) were observed at 6 years of age and followed annually until 9 years. A sequence of allometric models was fitted, that is, 1. body mass, stature, and PA; 2. addition of four PF tests; 3. addition of four more PF tests. In Model 1, changes in GMC are nonlinear, and body mass (-0.60 ± 0.07, P < .001) and stature (2.91 ± 0.35, P < .001) parameter estimates were significant suggesting children with a more linear body size/shape showed higher GMC performances. Girls tend to outperform boys across time, and PA was not associated with GMC changes. Model 2 fitted the data better, and the PF tests (handgrip, standing long jump, 50-yard dash, and shuttle run) were significantly linked to GMC change. In Model 3, adding the remaining PF tests did not change the order of any factors importance. The greatest GMC changes were achieved by children whose body size/shape has an ectomorphic dominance across the years. Considering that leaner and physically fitter children tended to be more coordinated, physical education should also focus on PF development in components related to muscular strength, speed, agility, and aerobic capacity, along with nutritional education to reduce fat mass.

Scaling waist girth for differences in body size reveals a new improved index associated with cardiometabolic risk.

Our aim was to examine whether a new ratio, waist divided by height0.5 (WHT.5R), is both independent of stature and a stronger predictor of cardiometabolic risk (CMR) than other anthropometric indices. Subjects (4117 men and 646 women), aged 20-69 years, were assessed for stature (cm), mass (kg), waist, and hip girths (cm) from which body mass index (BMI), waist-to-hip ratio (WHR), waist-to-height ratio (WHTR), and two new indices, a body shape index (ABSI) and WHT.5R, were determined. We used the allometric power law, W = a.HTb , to obtain a simple body shape index for waist girth (W) to be independent of stature (HT). Physical activity was determined using self-report, and physical fitness was determined using the Bruce protocol. Glucose, total cholesterol, low-density lipoprotein, high-density lipoprotein, triglycerides, and TC/HDL ratio were determined from fasting venous blood samples. A single CMR composite score was derived from log-transformed z-scores of Triglycerides + average blood pressure ((diastolic + systolic)/2) + glucose + HDL (*-1). Results confirmed WHT.5R to be independent of stature and the strongest predictor of CMR, compared with BMI, WC, WHR, ABSI, and WHTR. We also found that CMR scores decline significantly with increasing fitness and physical activity, confirming that being fit and active can compensate for the adverse effects of being fat as measured by all other anthropometric indices. In conclusion, WHT.5R was the best anthropometric index associated with CMR, and being both physically fit and active has a protective effect on CMR, irrespective of weight status.

Longitudinal development of match-running performance in elite male youth soccer players.

This study longitudinally examined age-related changes in the match-running performance of retained and released elite youth soccer players aged 8-18 years. The effect of playing position on age-related changes was also considered. Across three seasons, 263 elite youth soccer players were assessed in 1-29 competitive matches (988 player-matches). For each player-match, total distance and distances covered at age group-specific speed zones (low-speed, high-speed, sprinting) were calculated using 1 Hz or 5 Hz GPS. Mixed modeling predicted that match-running performance developed nonlinearly, with age-related changes best described with quadratic age terms. Modeling predicted that playing position significantly modified age-related changes (P < 0.05) and retained players covered significantly more low-speed distance compared with released players (P < 0.05), by 75 ± 71 m/h (mean ± 95% CI; effect size ± 95% CI: 0.35 ± 0.34). Model intercepts randomly varied, indicating differences between players in match-running performance unexplained by age, playing position or status. These findings may assist experts in developing training programs specific to the match play demands of players of different ages and playing positions. Although retained players covered more low-speed distance than released players, further study of the actions comprising low-speed distance during match play is warranted to better understand factors differentiating retained and released players.

Physical employment standards for U.K. fire and rescue service personnel.

BACKGROUND: Evidence-based physical employment standards are vital for recruiting, training and maintaining the operational effectiveness of personnel in physically demanding occupations. AIMS: (i) Develop criterion tests for in-service physical assessment, which simulate the role-related physical demands of UK fire and rescue service (UK FRS) personnel. (ii) Develop practical physical selection tests for FRS applicants. (iii) Evaluate the validity of the selection tests to predict criterion test performance. METHODS: Stage 1: we conducted a physical demands analysis involving seven workshops and an expert panel to document the key physical tasks required of UK FRS personnel and to develop 'criterion' and 'selection' tests. Stage 2: we measured the performance of 137 trainee and 50 trained UK FRS personnel on selection, criterion and 'field' measures of aerobic power, strength and body size. Statistical models were developed to predict criterion test performance. Stage 3: matter experts derived minimum performance standards. RESULTS: We developed single person simulations of the key physical tasks required of UK FRS personnel as criterion and selection tests (rural fire, domestic fire, ladder lift, ladder extension, ladder climb, pump assembly, enclosed space search). Selection tests were marginally stronger predictors of criterion test performance (r = 0.88-0.94, 95% Limits of Agreement [LoA] 7.6-14.0%) than field test scores (r = 0.84-0.94, 95% LoA 8.0-19.8%) and offered greater face and content validity and more practical implementation. CONCLUSIONS: This study outlines the development of role-related, gender-free physical employment tests for the UK FRS, which conform to equal opportunities law.

The need to redefine age- and gender-specific overweight and obese body mass index cutoff points.

For convenience, health practitioners and clinicians are inclined to classify people/patients as overweight or obese based on body mass index (BMI) cutoff points of 25 and 30 kg m(-2) respectively, irrespective of age and gender. The purpose of the current study was to identity whether, for the same levels of adiposity, BMI is the same across different age groups and gender. A two-way ANCOVA revealed significant differences in BMI between different age groups and gender (plus an interaction), using body fat (%) as the covariate, data taken from a random sample of the English population (n=2993). Younger people had greater BMI than older people for the same levels of adiposity (differences ranged by 4 BMI units for males, and 3 BMI units for females). In conclusion, if BMI thresholds for overweight (BMI=25 kg m(-2)) and obese (BMI=30 kg m(-2)) are to reflect the same levels of adiposity across all gender and age groups within a population, then age- and gender-specific BMI adjustments outlined here are necessary to more accurately/fairly reflect the same critical levels of adiposity.

Effect of fat free mass on serum and plasma BDNF concentrations during exercise and recovery in healthy young men.

Exercise results in release of brain derived neurotrophic factor into the circulation; however, little is known about the changes in serum and plasma brain derived neurotrophic factor concentrations and factors influencing brain derived neurotrophic factor during exercise and recovery. Serum (n=23) and plasma (n=10) brain derived neurotrophic factor concentrations were measured in healthy young men at rest, during steady-rate and after exercise to determine the maximum aerobic power. A two-way analysis of variance was used to investigate brain derived neurotrophic factor levels in blood during exercise and recovery, with one between-subject factor (a median split on: age, height, body mass, fat free mass, body mass index and aerobic fitness), and one within-subject factor (time). Serum brain derived neurotrophic factor concentrations increased in response to exercise and declined rapidly in recovery. Plasma brain derived neurotrophic factor had a greater proportional increase relative to exhaustive exercise compared with serum brain derived neurotrophic factor and was slower to return to near baseline values. There was a significant group-by-time interaction indicating a greater release and faster recovery for serum brain derived neurotrophic factor in high- compared with low-fat free mass individuals.

A 4-week instructed minimalist running transition and gait-retraining changes plantar pressure and force.

The purpose of this study is to compare changes in plantar pressure and force using conventional running shoes (CRS) and minimalist footwear (MFW) pre and post a 4-week MFW familiarization period. Ten female runners (age: 21 ± 2 years; stature: 165.8 ± 4.5 cm; mass: 55.9 ± 3.2 kg) completed two 11 km/h treadmill runs, 24 hours apart, in both CRS and MFW (pretest). Plantar data were measured using sensory insoles for foot strike patterns, stride frequency, mean maximum force ( M ⁢ F ¯ ), mean maximum pressure ( M ⁢ P ¯ ) and eight mean maximum regional pressures. Subjects then completed a 4-week familiarization period consisting of running in MFW and simple gait-retraining, before repeating the tests (posttest). During the pretests, 30% of subjects adopted a forefoot strike in MFW, following familiarization this increased to 80%; no change occurred in CRS. A significant decrease in M ⁢ F ¯ in both MFW and CRS (P = 0.024) was observed from pre-post, and a significant decrease in heel pressures in MFW. M ⁢ P ¯ was higher in MFW throughout testing (P < 0.001).A 4-week familiarization to MFW resulted in a significant reduction in M ⁢ F ¯ in both the CRS and MFW conditions, as well as a reduction in heel pressures. Higher M ⁢ P ¯ was observed throughout testing in the MFW condition.

A field-test battery for elite, young soccer players.

The validity and reliability of a battery of field-based performance tests was examined. The opinions of coaches, fitness professionals and players (n=170, 172 and 101 respectively) on the importance of performance testing were established using a questionnaire. On 2 occasions, separated by 7 days, 80 elite, young soccer players (mean±SD [and range]: age 13.2±2.6 [8.9-19.1] years; stature 1.59±0.18 m [1.32-1.91]; body mass 50.6±17.1 [26.5-88.7] kg) completed a battery of field-based tests comprised of heart rate response to a submaximal Multi-stage fitness test, 3 types of vertical jump, sprints over 10 and 20 m, and an agility test. Physical performance testing was considered important by coaches (97%), fitness professionals (94%) and players (83%). The systematic bias ratio and the random error components of the 95% ratio limits of agreement for the first and second tests, for the U9-U11 vs. U12-U14 vs. U15-U18 age groups, were [Systematic bias (*/÷ ratio limits)]: Heart rate (Level 5): 0.983 (*/÷ 1.044) vs. 0.969 (*/÷ 1.056) vs. 0.983 (*/÷ 1.055); Rocket jump: 0998 (*/÷ 1.112) vs. 0.999 (*/÷ 1.106) vs. 0.996 (*/÷ 1.093); 10 m sprint: 0.997 (*/÷ 1.038) vs. 0.994 (*/÷ 1.033) vs. 0.994 (*/÷ 1.038); Agility test: 1.010 (*/÷1.050) vs. 1.014 (*/÷1.050) vs. 1.002 (*/÷1.053). All tests, except heart rate recovery from the Multi-stage fitness test, were able to distinguish between different ability and age groups of players (p<0.05). Thus, the field-test battery demonstrated logical and construct validity, and was shown to be a reliable and objective tool for assessing elite, young soccer players.

Colorectal cancer incidence and trend in UK South Asians: a 20-year study.

AIMS: South Asians comprise 13.6% of the Wolverhampton population. We aimed to compare the incidence and trend of colorectal cancer in this subgroup with the non South Asian population over a 20-year period. METHOD: Patients of South Asian origin diagnosed with colorectal cancer from 1989 to 2008 were identified from the hospital histopathology database and compared with those of non South Asian origin. 1991 and 2001 census data were used to standardize for differing age and sex distributions in the two study populations. RESULTS: The median unadjusted incidence of colorectal cancer from 1989 to 2008 was 6.17 per 100,000 per year in South Asians compared with 71.70 per 100,000 per year in non South Asians (77.79% white British). The age and sex adjusted odds ratio for colorectal cancer in South Asians was 0.2 (P < 0.001). There was an equal increased trend in the incidence in both the South Asians and non South Asians over the study period (0.8% per year). In patients < 50 years, the gender difference in the incidence of cancer was not significant, but as age increased this rose significantly (males > females). CONCLUSION: There was a markedly lower incidence of colorectal cancer in South Asians compared with non South Asians, maintained over 20 years. Colorectal cancer incidence increased by a small and similar amount over the period in both groups. There was a male preponderance of colorectal cancer in both populations over 50 years.

Physical activity, walking and leanness: an analysis of the Northern Ireland Sport and Physical Activity Survey (SAPAS).

OBJECTIVE: To report on the contribution walking makes to total weekly physical activity and the relationship between the volume and intensity of walking and leanness in a representative sample of the Northern Ireland population. METHOD: 4563 adults participated in this cross-sectional survey of physical activity behaviour. Self-reported height and weight was used to determine inverse body mass index (iBMI) as a measure of leanness. Data across all domains of physical activity including self-reported volume and intensity of walking (in bouts of 10 min or more) were analysed to determine their contribution to leanness using ANCOVA, having controlled for age, gender, socio-economic and smoking status. RESULTS: Over 68% of the participants reported walking >10 minutes during the previous week but only 24% report walking at a brisk or fast pace. Time walking at a brisk or fast pace for personal transport was identified as having the strongest positive association with being lean (F(1,4256)=10.45, ß=0.051 cm(2) kg(-1) min(-1) (SE=0.016),P=0.001). CONCLUSIONS: In addition to increasing the amount of walking and the percentage of people walking regularly, public health messages encouraging an increase in walking pace may be valuable to increase the proportion of the population meeting physical activity guidelines and gaining associated health benefits.

Modelling the determinants of 2000 m rowing ergometer performance: a proportional, curvilinear allometric approach.

Previous studies have investigated the determinants of indoor rowing using correlations and linear regression. However, the power demands of ergometer rowing are proportional to the cube of the flywheel's (and boat's) speed. A rower's speed, therefore, should be proportional to the cube root (0.33) of power expended. Hence, the purpose of the present study was to explore the relationship between 2000 m indoor rowing speed and various measures of power of 76 elite rowers using proportional, curvilinear allometric models. The best single predictor of 2000 m rowing ergometer performance was power at VO(2max)(WVO(2max))(0.28), that explained R(2)=95.3% in rowing speed. The model realistically describes the greater increment in power required to improve a rower's performance by the same amount at higher speeds compared with that at slower speeds. Furthermore, the fitted exponent, 0.28 (95% confidence interval 0.226-0.334) encompasses 0.33, supporting the assumption that rowing speed is proportional to the cube root of power expended. Despite an R(2)=95.3%, the initial model was unable to explain "sex" and "weight-class" differences in rowing performances. By incorporating anaerobic as well as aerobic determinants, the resulting curvilinear allometric model was common to all rowers, irrespective of sex and weight class.

Vibration training improves balance in unstable ankles.

Functional ankle instability (FAI) is a common condition following ankle injury characterised by increased risk of injury. Ankle sprains are a common acute form of injury suffered in dancing and loss of balance can affect not only risk of injury risk but also performance aesthetics. Whole body vibration training (WBVT) is a new rehabilitation method that has been linked with improving balance and muscle function. 38 female dancers with self reported unilateral FAI were randomly assigned in 2 groups: WBVT and control. Absolute centre of mass (COM) distribution during single leg stance, SEBT normalised research distances and Peroneus longus mean power frequency (f(med)) where measured pre and post 6-week intervention. There was a significant improvement in COM distribution over the 6 weeks from 1.05 ± 0.57 to 0.33 ± 0.42 cm² (P<0.05), and 4 of the 8 planes of direction in the SEBT Ant, Antlat, Med and Antmed from 77.5 ± 7.1 to 84.1 ± 5.8% (P<0.05) compared to control groups during the course of the 6 week training intervention. There was no evidence of improvement in peroneus longus (f(med)) over time (P=0.915) in either group. WBVT improved static balance and SEBT scores amongst dancers exhibiting ankle instability but did not affect peroneus longus muscle fatigue.

Effect of leg length on ROM, VJ and leg dexterity in dance.

We investigated the associations between leg length and specific ballet movements in different skill groups. Volunteers were from an undergraduate dance programme (n=18), a pre-professional school (n=43) and from an elite classical ballet company (n=45). Individual data were collected for anthropometry, vertical jump, leg dexterity, and leg active and passive ROM. ANCOVA identified both main effects as significant with regard to vertical jump (gender P<0.001 and skill P=0.017); leg length was also identified as a significant covariate (P=0.023). Analysis of leg dexterity identified no significant effects with gender, skill or leg length. Active and passive range of motion noted gender (P=0.001) and skill (P<0.001) differences. Leg length was found to be negatively associated with both active and passive ROM (P=0.002). In conclusion, the present data highlight the diverse and conflicting effects of leg length on fundamental ballet skills. The longer legs that benefit vertical jump have a negative influence on range of motion and leg dexterity except for highly skilled dancers, who through skill, seem to have overcome the effects of some of these dichotomies.

Bone status in professional cyclists.

Professional cycling combines extensive endurance training with non weight-bearing exercise, two factors often associated with lower bone mineral density (BMD). Therefore BMD was measured with dual-energy x-ray absorptiometry in 30 professional road cyclists (mean (SD) age: 29.1 (3.4) years; height: 178.5 (6.7) cm; weight: 71.3 (6.1) kg; %fat mass: 9.7 (3.2)%; VO (2)max: 70.5 (5.5) ml.kg (-1).min (-1)) and in 30 young healthy males used as reference (28.6 (4.5) years; 176.5 (6.3) cm; 73.4 (7.3) kg; 20.7 (5.8)%). Adjusting for differences in age, height, fat mass, lean body mass, and calcium intake by ANCOVA, professional cyclists had similar head BMD (p=0.383) but lower total body (1.135 (0.071) vs. 1.248 (0.104) g.cm (-2); p<0.001), arms (0.903 (0.075) vs. 0.950 (0.085), p=0.028), legs (1.290 (0.112) vs. 1.479 (0.138); p<0.001), spine (0.948 (0.100) vs. 1.117 (0.147) g.cm (-2); p<0.001), pelvis (1.054 (0.084) vs. 1.244 (0.142), p<0.001), lumbar spine (1.046 (0.103) vs. 1.244 (0.167), P<0.001), and femoral neck BMD (0.900 (0.115) vs. 1.093 (0.137), p<0.001) compared to reference subjects. Professional cycling appears to negatively affect BMD in young healthy and highly active males, the femoral neck being the most affected site (-18%) in spite of the elevated muscle contractions inherent to the activity.

Individualised assessment of response to clopidogrel in patients presenting with acute coronary syndromes: a role for short thrombelastography?

INTRODUCTION: There is considerable interindividual variation in response to the antiplatelet agent clopidogrel. Hyporesponse predicts negative outcomes in patients presenting with a variety of ischemic cardiac conditions and following intracoronary stent placement. Many tests of clopidogrel activity are time consuming and complex. Short thromboelastography (s-TEG) allows rapid measurement of platelet clopidogrel response. AIMS: We initiated this study to investigate the utility of s-TEG in assessing the response to clopidogrel in patients presenting with acute coronary syndromes (ACS) and to compare these results with established clopidogrel monitoring techniques. METHODS: Patients admitted with unstable angina (UA) or Non ST elevation myocardial infarction (NSTEMI) undergoing coronary angiography were recruited. After routine loading with clopidogrel, all patients were tested with s-TEG and Accumetrics Verify-Now rapid platelet function analyzer (VN-RPFA). We used the modified TEG technique of measuring area under the curve at 15 min (AUC15), which allows a rapid estimation of antiplatelet response. Vasodilator-stimulated phosphoprotein phosphorylation (VASP) was also tested in a subgroup of patients. Clinical follow-up was obtained at 1 year. s-TEG results were correlated with VN-RPFA and VASP findings. RESULTS: A total of 49 patients (33 male, mean age 63) were recruited and tested with s-TEG and VN-RPFA and a total of 39 patients were also assessed with VASP. s-TEG readings correlated well with VN-RPFA (r(2)= 0.54, P < 0.0001) and VASP (r(2)= 0.26, P= 0.001). CONCLUSION: s-TEG provides timely results which compare to current tests of clopidogrel activity. This technique can also be used to measure a variety of other clotting parameters and as such could develop into a valuable near patient test for the interventional cardiologist.

Scaling concept II rowing ergometer performance for differences in body mass to better reflect rowing in water.

We investigated whether the concept II indoor rowing ergometer accurately reflects rowing on water. Forty-nine junior elite male rowers from a Great Britain training camp completed a 2000 m concept II model C indoor rowing ergometer test and a water-based 2000 m single-scull rowing test. Rowing speed in water (3.66 m/s) was significantly slower than laboratory-based rowing performance (4.96 m/s). The relationship between the two rowing performances was found to be R2=28.9% (r=0.538). We identified that body mass (m) made a positive contribution to concept II rowing ergometer performance (r=0.68, P<0.001) but only a small, non-significant contribution to single-scull water rowing performance (r=0.039, P=0.79). The contribution that m made to single-scull rowing in addition to ergometer rowing speed (using allometric modeling) was found to be negative (P<0.001), confirming that m has a significant drag effect on water rowing speed. The optimal allometric model to predict single-scull rowing speed was the ratio (ergometer speed xm(-0.23))1.87 that increased R2 from 28.2% to 59.2%. Simply by dividing the concept II rowing ergometer speed by body mass (m0.23), the resulting "power-to-weight" ratio (ergometer speed xm(-0.23)) improves the ability of the concept II rowing performance to reflect rowing on water.