Stephen-Mark Cooper

Evidence from randomised controlled trials did not support the introduction of dietary fat guidelines in 1977 and 1983: a systematic review and meta-analysis

Objectives National dietary guidelines were introduced in 1977 and 1983, by the US and UK governments, respectively, with the ambition of reducing coronary heart disease (CHD) by reducing fat intake. To date, no analysis of the evidence base for these recommendations has been undertaken. The present study examines the evidence from randomised controlled trials (RCTs) available to the US and UK regulatory committees at their respective points of implementation. Methods A systematic review and meta-analysis were undertaken of RCTs, published prior to 1983, which examined the relationship between dietary fat, serum cholesterol and the development of CHD. Results 2467 males participated in six dietary trials: five secondary prevention studies and one including healthy participants. There were 370 deaths from all-cause mortality in the intervention and control groups. The risk ratio (RR) from meta-analysis was 0.996 (95% CI 0.865 to 1.147). There were 207 and 216 deaths from CHD in the intervention and control groups, respectively. The RR was 0.989 (95% CI 0.784 to 1.247). There were no differences in all-cause mortality and non-significant differences in CHD mortality, resulting from the dietary interventions. The reductions in mean serum cholesterol levels were significantly higher in the intervention groups; this did not result in significant differences in CHD or all-cause mortality. Government dietary fat recommendations were untested in any trial prior to being introduced. Conclusions Dietary recommendations were introduced for 220 million US and 56 million UK citizens by 1983, in the absence of supporting evidence from RCTs.

Anthropometric and kinematic influences on release speed in men's fast-medium bowling.

The main aim of this study was to identify significant relationships between selected anthropometric and kinematic variables and ball release speed. Nine collegiate fast-medium bowlers (mean - s : age 21.0 - 0.9 years, body mass 77.2 - 8.1 kg, height 1.83 - 0.1 m) were filmed and reconstructed three-dimensionally. Ball release speeds were measured by a previously validated Speedchek™ Personal Sports Radar (Tribar Industries, Canada). Relationships between selected anthropometric variablesand ball release speed and between kinematic variables and ball release speed were investigated using Pearsons product-moment correlation coefficients ( r ). A significant relationship was found between the horizontal velocity during the pre-delivery stride ( r = 0.728, P ≪ 0.05) and ball release speed (31.5 - 1.9 m·s -1 ). We believe that the high correlation was due to the bowlers using techniques that allowed them to contribute more of the horizontal velocity created during the run-up to ball release speed. We also found that the angular velocity (40.6 - 3.4 rad·s -1 ) of the right humerus had a low correlation ( r = 0.358, P > 0.05) with ball release speed. Although the action of the wrist was not analysed because of an inadequate frame rate, we found high correlations between ball release speed and shoulder-wrist length (661 - 31 mm; r = 0.626, P ≪ 0.05) and ball release speed and total arm length (860 - 36 mm; r = 0.583, P ≪ 0.05). We conclude that the variance in release speed within this group may be accounted for by the difference in radial length between the axis of rotation at the glenohumeral joint and the release point.

The Effects of Time and Intensity of Exercise on Novel and Established Markers of CVD in Adolescent Youth

This article examines the effects of brief, intense exercise in comparison with traditional endurance exercise on both novel and traditional markers of cardiovascular disease (CVD) in youth.

The repeatability and criterion related validity of the 20 m multistage fitness test as a predictor of maximal oxygen uptake in active young men

Objective: To investigate the repeatability and criterion related validity of the 20 m multistage fitness test (MFT) for predicting maximal oxygen uptake (Vo2max) in active young men. Methods: Data were gathered from two phases using 30 subjects (x̄±s; age = 21.8±3.6 years, mass = 76.9±10.7 kg, stature = 1.76±0.05 m). MFT repeatability was investigated in phase 1 where 21 subjects performed the test twice. The MFT criterion validity to predict Vo2max was investigated in phase 2 where 30 subjects performed a continuous incremental laboratory test to volitional exhaustion to determine Vo2max and the MFT. Results: Phase 1 showed non-significant bias between the two applications of the MFT (x̄diff±sdiff = −0.4±1.4 ml kg−1 min−1; t = −1.37, p = 0.190) with 95% limits of agreement (LoA) ±2.7 ml kg−1 min−1 and heteroscedasticity 0.223 (p = 0.330). Log transformation of these data reduced heteroscedasticity to 0.056 (p = 0.808) with bias −0.007±0.025 (t = −1.35, p = 0.190) and LoA±0.049. Antilogs gave a mean bias on the ratio scale of 0.993 and random error (ratio limits) ×/÷1.050. Phase 2 showed that the MFT significantly underpredicted Vo2max (x̄diff±sdiff = 1.8±3.2 ml kg−1 min−1; t = 3.10, p = 0.004). LoA were ±6.3 ml kg−1 min−1 and heteroscedasticity 0.084 (p = 0.658). Log transformation reduced heteroscedasticity to −0.045 (p = 0.814) with LoA±0.110. The significant systematic bias was not eliminated (x̄diff±sdiff = 0.033±0.056; t = 3.20, p = 0.003). Antilogs gave a mean bias of 1.034 with random error×/÷1.116. Conclusions: These findings lend support to previous investigations of the MFT by identifying that in the population assessed it provides results that are repeatable but it routinely underestimates Vo2max when compared to laboratory determinations. Unlike previous findings, however, these results show that when applying an arguably more appropriate analysis method, the MFT does not provide valid predictions of Vo2max.

Counterfeiting in performance‐ and image‐enhancing drugs

The current drastic escalation in obesity may be contributing to the exponential rise in drugs used for image enhancement. Drugs such as anabolic-androgenic steroids (AAS) are perceived as a viable method of achieving a perfect physique. They are also the most widely abused drugs in sport. The Internet has encouraged the abuse of expensive drugs, particularly human growth hormone (hGH), resulting in increased importation for personal use. The substantial increase in this market has opened up avenues for counterfeiting, estimated as a multi-million pound business. The acute adverse effects from contaminated vials may result in a variety of pathologies including communicable diseases. In 2007, in the UK, a series of intramuscular abscesses, requiring surgical treatment, led us to study samples obtained from the underground market. The analysis of 38 parenteral samples and 19 oral samples of tablets was performed by a World Anti-Doping Agency (WADA) accredited laboratory, in an attempt to establish the extent of available counterfeit products. Fifty-three per cent (20) of the injectable AAS esters and 21% (4) of the oral tablets were counterfeit. Culture and sensitivity revealed the presence of skin commensal organisms, which may have contributed to the development of the abscesses. Users of AAS and hGH for sport, including bodybuilding, are currently risking their health because of counterfeit and poorly controlled products.

Direct Hits to the Head during Amateur Boxing is Associated with a Rise in Serum Biomarkers for Brain Injury

Boxing exposes participants to the physiological response to high intensity exercise and also to direct body and brain trauma. Amateur boxing is increasing and females have also been included in the Olympics. The aim of this study is to assess the stress response and possible brain injury incurred during a match by measuring serum biomarkers associated with stress and cellular brain injury before and after combat. Sixteen male amateur boxers were studied retrospectively. The study population was divided into two groups: (a) a group that received predominantly punches to the head (PTH) and (b) a group that received predominantly punches to the body (PTB). Blood samples were taken before and five minutes after each contest. They were analysed for S-100B, neuron-specific enolase (NSE), creatine kinase (CK) and cortisol. The PTH group received direct contacts to the head (not blocked, parried or avoided) and to the body (n=8, age: 17.6 ± 5.3, years; height: 1.68 ± 0.13, meters; mass: 65.4 ± 20.3, kg). The PTB group received punches to the body including blocked and parried punches, but received no direct punches to the head, (n=8, mean ± SD, age: 19.1 ± 3.2 years; height: 1.70 ± 0.75, meters; mass: 68.5 ± 15 kg). Significant increases (P<0.05) were observed between pre- and post-combat serum concentrations in serum concentrations in PTH of S-100B (0.35 ± 0.61 vs. 0.54 ± 0.73, μg.L−1) NSE (19.7 ± 14 vs.31.1 ± 26.6, ng.ml−1) and cortisol (373 ± 202 vs. 756± 93, nmol.L−1). Significant increases (P<0.05) of creatine kinase were recorded in both groups. This study demonstrates significant elevations in neurochemical biomarkers in boxers who received direct blows to the head. However, further work is required to quantify this volumetric brain damage and long term clinical sequelae.

C-reactive protein in schoolchildren and its relation to adiposity, physical activity, aerobic fitness and habitual diet

Objective: To investigate the relation between C-reactive protein (CRP), adiposity, physical activity, aerobic fitness and habitual diet in a cohort of schoolchildren. Methods: A cross-sectional study of 164 schoolchildren aged 12–13 years was conducted in two schools. Adiposity was estimated using body mass index and waist circumference. Blood samples were taken after an overnight fast and measured for CRP. Aerobic fitness and habitual physical activity were assessed using the 20 metres multistage fitness test, and a seven-day recall, respectively. A seven-day food diary provided measures of dietary intake. Results: To improve the distribution of this variable, CRP levels were logarithmically transformed in all analyses. There was no significant difference in mean CRP concentration between boys (1.07 (1.33) mg/l) and girls (1.24 (1.87) mg/l) (p⩾0.05). Compared to girls, boys reported significantly higher (i) aerobic fitness 59.2 (20.3) shuttles vs 42.9 (15.3) shuttles, (ii) vigorous activity levels per week 92 (123) minutes vs 11.2 (34.6) minutes and (iii) waist circumference 69.8 (1.1) cm vs 65.2 (0.9) cm (p⩽0.05). Among boys and girls, adiposity was significantly associated with log transformed CRP (p⩽0.05). CRP was not significantly related to any other variable. Conclusion: Elevated CRP was evident in this cohort; however, whether high CRP levels during childhood and adolescence leads to an increased risk of CVD in later life has not been determined. Adiposity was related to CRP concentration, suggesting that reducing adiposity may be effective in lowering CRP and preventing future cardiovascular events.

Analysis procedures for non-parametric data from performance analysis

It is vital that the reliability of a data gathering system is demonstrated clearly and in a way that is compatible with the intended analyses of the data. The data must be tested in the same way and to the same depth in which it will be processed in the subsequent analyses. In general, the work of Bland and Altman (1986) has transformed the attitude of sport scientists to testing reliability; can similar techniques be applied to the non-parametric data that most notational analysis studies generate? There are also a number of questions that inherently re-occur in these forms of data-gathering – this study aims to demonstrate practical answers to some of these questions. The most common form of data analysis in notation studies is to record frequencies of actions and their respective positions on the performance area, these are then presented as sums or totals in each respective area. What are the effects of cumulative errors nullifying each other, so that the overall totals appear less incorrect than they actually are? The application of parametric statistical techniques is often misused in notational analysis - how does this affect the confidence of the conclusions to say something about the data, with respect to more appropriate non-parametric tests? Analysing 72 research papers recently published under the banner of notational analysis, it was found that 70% did not report any reliability study and a large proportion of the remaining used questionable processes given the recent ideas in reliability testing in sports science (Atkinson, G. and Nevill, A. (1998) Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sports Med., 26, 217–238). In some cases the reliability studies were executed on summary data, and the system was then assumed to be reliable for all of the other types of more detailed data analyses that were produced. By using practical examples from recent research and consultancy projects, undergraduate and postgraduate studies, this research investigated these issues associated with reliability studies and subsequent analyses in performance analysis, in order to give practical guidelines to enable establishing simple and reliable comparisons of non-parametric sets of data.

Physical activity interventions: effects of duration and intensity

The purpose of this study was to examine the effects of exercising at different intensities over 7 weeks on components of physical fitness and CVD risk factors. Forty‐seven boys and 10 girls, (16.4±0.7 years of age) were divided into a moderate, high intensity, or a control group. All participants had indices of obesity and blood pressure recorded in addition to four physical performance measures pre‐ and post‐intervention. In addition, the intervention groups repeated the physical performance measures at the 4th week phase of the intervention. Following the intervention, significant improvements (P<0.05) in the high‐intensity group were found in the 20 MSFT, agility, CMJ and 10 m sprint post‐intervention. Participants in the moderate intensity group displayed significant improvements (P<0.05) in both the CMJ and 20 MSFT post‐intervention. Body fat % significantly improved (P<0.01) in the moderate group only post‐intervention. Interestingly, Systolic blood pressure significantly improved post‐intervention (112±10 vs 106±11 mmHg) (P=0.017) in the high intensity group. In conclusion, high‐intensity exercise over 7 weeks is a very time efficient means of improving important components of physical fitness in adolescents.

A simple statistical method for assessing the reliability of data entered into sport performance analysis systems

The purpose of this srudy was to present a method for Assessing a reliability based upon Bland and Altman’s (1999) suggestions for the non-parametric treatment of comparison data and the proposals of Nevill et al. (2001) who recommended that 95% of differences should be recorded within a reference value thought to be of ‘no practical importance’. In this study, it is shown how the analyst can apply the method when individual sport performance indicators are treated as individual variables. A simple notation analysis test-retest ‘experiment’ is described, and the intraobserver data collected by one subject was used for illustrative purposes to explain how the necessary graphical, point estimate and confidence interval computations are made. The notational analyses of a further three volunteer subjects are considered in order to investigate the sensitivity of the method. The method is a simple measure of absolute agreement that is sensitive enough to distinguish between the successes and errors made by expert, experienced and improving sport performance analysts. The method is also free from the assumptions of normality, does not depend upon high within-systems variance and it can be applied successfully to individual performance indicators in the development of sport performance analysts and analysis systems.