Can greater muscularity in larger individuals resolve the 3/4 power-law controversy when modelling maximum oxygen uptake?

BACKGROUND: The power function relationship, MR = a.m(b), between metabolic rate (MR) and body mass m has been the source of much controversy amongst biologists for many years. Various studies have reported mass exponents (b) greater than the anticipated 'surface-area' exponent 0.67, often closer to 0.75 originally identified by Kleiber. AIM: The study aimed to provide a biological explanation for these 'inflated' exponents when modelling maximum oxygen uptake (max), based on the observations from this and previous studies that larger individuals develop disproportionately more muscle mass in the arms and legs. RESEARCH DESIGN AND SUBJECTS: A cross-sectional study of 119 professional soccer players from Croatia aged 18-34 was carried out. RESULTS: Here we confirm that the power function relationship between max and body mass of the professional soccer players results in an 'inflated' mass exponent of 0.75 (95% confidence interval from 0.56 to 0.93), but also the larger soccer players have disproportionately greater leg muscle girths. When the analysis was repeated incorporating the calf and thigh muscle girths rather than body mass as predictor variables, the analysis not only explained significantly more of the variance in max, but the sum of the exponents confirmed a surface-area law. CONCLUSIONS: These findings confirm the pitfalls of fitting body-mass power laws and suggest using muscle-girth methodology as a more appropriate way to scale or normalize metabolic variables such as max for individuals of different body sizes

The validity of capillary blood sampling in the determination of human growth hormone concentration during exercise in men

This is an open access article - Copyright © 2004 BMJ Publishing Group LtdBACKGROUND: Studies measuring human growth hormone (hGH) in blood during exercise have mainly used venous sampling. The invasive nature of this procedure makes evaluation of hGH impossible in various exercise environments. OBJECTIVE: To determine whether capillary sampling could offer an alternative sampling method. METHODS: Capillary and venous blood samples were collected for determination of hGH at the end of each exercise stage during an incremental exercise test in 16 male club level competitive cyclists (mean (SD) age 30.8 (8.0) years, body mass 72.2 (7.1) kg, body fat 12.9 (3.5)%, peak oxygen consumption 4.18 (0.46) l⋅min−1). Linear regression, from a plot of venous v capillary blood hGH concentration, showed a correlation coefficient of r = 0.986 (p<0.001). When geometric means and log transformations were used, a coefficient of variation of 14.2% was demonstrated between venous and capillary flow for hGH concentration. The mean ratio limits of agreement were 0.62 (1.72)—that is, 95% of the ratios were contained between 0.36 and 1.07, with a mean of 0.62. CONCLUSIONS: Capillary blood sampling is an acceptable alternative to venous sampling for determining hGH concentration during rest and exercise. Sample sites should not be used interchangeably: one site should be chosen and its use standardised

Commentary on the article "improving the prediction of maturity from anthropometric variables using a maturity ratio"

Published versio

Do pedometers motivate people to walk more?

Physical activity confers many important health benefits. The 'active living message' recommends that adults should accumulate 30 ruin of moderate-intensity physical activity (e.g. brisk walking) on most--preferably all--days of the week, but the populations of most developed countries are not meeting this target. Walking is one mode of activity that most people can do without skills, equipment, facilities or extra expense and walking has less bias in terms of age, sex and social class than facility-based exercise. Thus we need to investigate interventions that promote walking

Characteristics associated with 10-km running performance among a group of highly trained male endurance runners age 21-63 years

This study assessed physiological and cardiac factors associated with 10-km running performance in a group of highly trained endurance runners age 21-63 years. Participants (N = 37) underwent a resting echocardiograph and incremental treadmill running test. They also provided information on their recent 10-km races. Data were analyzed using &quot;best subsets&quot; multiple regression. Declines with age were found for 10-km running speed (0.26 m · s-1 · decade-1), maximum heart rate (4 beats/decade), VO2peak (6 ml · kg-1 · min-1 · decade-1), velocity at lactate threshold (1 m · s-1 · decade-1), and VO2 at lactate threshold (4 ml · kg-1 · min-1 · decade-1). The percentage of VO2peak at which lactate threshold occurred increased with age by 1.5% per decade. The rate of change of displacement of the atrioventricular plane at the left free wall and septum both declined by 1 cm · s-1 · decade-1. The best single predictor of 10-km running speed was velocity at lactate threshold

Scanning Electron Microscopy of the Mammalian Organ of Corti: Assessment of Preparative Procedures

Different fixation, drying and coating procedures have been applied in preparation of the organ of Corti for scanning electron microscopy (SEM), and structural features of the apical surface of the tissue in unfixed, freeze-fractured preparations used in assessing their effects on morphology. Fixation with glutaraldehyde alone or osmium tetroxide alone causes artefacts that are substantially avoided when tissue is doubly fixed in glutaraldehyde followed by osmium. Significant improvements in preservation are also obtained when tissue is additionally processed through thiocarbohydrazide-osmium (TOTO) processing. In addition to providing a conducting coat, it stabilises the tissue against deformations that might otherwise occur during drying, and reduces the extent of tissue shrinkage. Freeze-drying of TOTO processed tissue produces less tissue distortion than critical point drying (CPD) but is not so easy to apply routinely. The distortions of structure in TOTO-processed CPD tissue are not significant and this may be the preferred procedure for routine use, but air drying from hexamethyldisilazane is a useful alternative, producing results as good as those from CPD samples if TOTO processing is applied beforehand. One particular advantage of freeze-drying, though, is that after freezing, brittle fracture through the tissue can occur making examination of intracellular structure by SEM relatively easy. However, again, TOTO processing prior to freezing is of value as this appears to prevent the formation of large ice-crystal during freezing. Examination of isolated outer hair cells by SEM shows that isolation procedures do not cause significant damage to the stereociliary bundles

Correction: The Complete Sequence of the Acacia ligulata Chloroplast Genome Reveals a Highly Divergent clpP1 Gene

The authors would like to amend this article based on the discovery that the originally published Acacia ligulata sequence contains assembly errors, which came to light after the publication of the article

Integration of complete chloroplast genome sequences with small amplicon datasets improves phylogenetic resolution in Acacia

Combining whole genome data with previously obtained amplicon sequences has the potential to increase the resolution of phylogenetic analyses, particularly at low taxonomic levels or where recent divergence, rapid speciation or slow genome evolution has resulted in limited sequence variation. However, the integration of these types of data for large scale phylogenetic studies has rarely been investigated. Here we conduct a phylogenetic analysis of the whole chloroplast genome and two nuclear ribosomal loci for 65 Acacia species from across the most recent Acacia phylogeny. We then combine this data with previously generated amplicon sequences (four chloroplast loci and two nuclear ribosomal loci) for 508 Acacia species. We use several phylogenetic methods, including maximum likelihood bootstrapping (with and without constraint) and ExaBayes, in order to determine the success of combining a dataset of 4000 bp with one of 189,000 bp. The results of our study indicate that the inclusion of whole genome data gave a far better resolved and well supported representation of the phylogenetic relationships within Acacia than using only amplicon sequences, with the greatest support observed when using a whole genome phylogeny as a constraint on the amplicon sequences. Our study therefore provides methods for optimal integration of genomic and amplicon sequences

An Evaluation of Prediction Equations for the 6 Minute Walk Test in Healthy European Adults Aged 50-85 Years

This study compared actual 6 minute walk test (6MWT) performance with predicted 6MWT using previously validated equations and then determined whether allometric modelling offers a sounder alternative to estimating 6MWT in adults aged 50-80 years.We compared actual 6MWT performance against predicted 6MWT in 125 adults aged 50-85 years (62 male, 63 female). In a second sample of 246 adults aged 50-85 years (74 male, 172 female), a new prediction equation for 6MWT performance was developed using allometric modelling. This equation was then cross validated using the same sample that the other prediction equations were compared with.Significant relationships were evident between 6MWT actual and 6MWT predicted using all of the commonly available prediction equations (all P<0.05 or better) with the exception of the Alameri et al prediction equation (P>0.05). A series of paired t-tests indicated significant differences between 6MWT actual and 6MWT predicted for all available prediction equations (all P<0.05 or better) with the exception of the Iwama et al equation (P = .540). The Iwama et al equation also had similar bias (79.8m) and a coefficient of variation of over 15%. Using sample 2, a log-linear model significantly predicted 6MWT from the log of body mass and height and age (P = 0.001, adjusted R2 = .526), predicting 52.6% of the variance in actual 6MWT. When this allometric equation was applied to the original sample, the relationship between 6MWT actual and 6MWT predicted was in excess of values reported for the other previously validated prediction equations (r = .706, P = 0.001). There was a significant difference between actual 6MWT and 6MWT predicted using this new equation (P = 0.001) but the bias, standard deviation of differences and coefficient of variation were all less than for the other equations.Where actual assessment of the 6MWT is not possible, the allometrically derived equation presented in the current study, offers a viable alternative which has been cross validated and has the least SD of differences and smallest coefficient of variation compared to any of the previously validated equations for the 6MWT

The effect of match standard and referee experience on the objective and subjective match workload of English Premier League referees

The aim of the present study was to examine the effect of match standard and referee experience upon the objective and subjective workload of referees during Premier and Football league soccer matches. We also examined the relationship between heart rate (HR) and ratings of perceived exertion (RPE) for assessing match intensity in soccer referees. Heart rate responses were recorded using short-range telemetry and RPE scores were collected using a 10-point scale. Analysis revealed a significant relationship between mean match HR and match RPE scores (r = 0.485, p &lt; 0.05, n =18). There were significant differences in match HR (Premier league 83.6 2.6 %HRmax vs. Football league 81.5 2.2 %HRmax, p &lt; 0.05) and match RPE scores (Premier league 7.8 0.8 vs. Football league 6.9 0.8, p &lt; 0.05) between standards of competition. Referee experience had no effect upon match heart rate and RPE responses to Premier and Football league matches. The results of the present study demonstrate the validity of using HR and RPE as a measure of global match intensity in soccer referees. Referee experience had no effect upon the referees’ objective and subjective match workload assessments, whereas match intensity was correlated to competition standard. These findings have implications for fitness preparation and evaluation in soccer referees. When progressing to a higher level of competition, referees should ensure that appropriate levels of fitness are developed in order to enable them to cope with an increase in physical match demands