The reliability and validity of gas exchange kinetics, maximal aerobic power, anaerobic threshold and sport specific protocols as determinants of fitness in elite athletes.

The aim of this research was to produce reliable and valid new fitness assessments utilising both gas exchange kinetics and sport specific field testing for the determination of fitness in elite athletic groups. A series of studies were conducted on both track runners and soccer players to examine the usefulness of maximal, submaximal and sport specific procedures. The physiological measurements utilisedin this research were: gas exchange kinetics, maximum aerobic power (VO2 max), anaerobic threshold and a soccer specific fitness test. The research developed new procedures and modified existing protocols to challenge athletes appropriately in the examination of relevant athletic performance indicators. For the determination of test reliability and validity, test-retest analysis was performed and cross-sectional comparisons were made between performers of both different standards of performance and event specialisms. The submaximal gas exchange kinetics test enabled the differentiation of elite sprinters from elite endurance runners. A test-retest reliability study of that procedure revealed high test variability (measurement error range: 18 - 35%), possibly due to breath-by-breath fluctuations. The development of a mean response time through a mathematical modelling technique improved the confidence in this procedure (test-retest measurement error: 16%) and produced a single, overall, measurement to enhance the future application of the procedure for the assessment of aerobic fitness in different population groups. Nevertheless, relatively high test-retest variability remains a feature of the test. Further research examined the validity of standard laboratory and sport specific measurements in the determination of training status in professional soccer players. Maximal aerobic power was shown to be unaffected by short-term (5 weeks) changes in training status (63.3 +/-5.8 ml-kg-1min-1 and 62.1 +/-4.9 ml-kg-1min-1) , questioning the relevance of this measurement to routine assessment of fitness and training status. Conversely, the soccer specific fitness test enabled the differentiation between soccer players performing at differentstandards where there was no difference in estimated VO2 max, however there was norelationship between V02 max and the soccer test which questions the validity of the new field test. Nevertheless, it is possible that this result reflects a greater sensitivity of the new test to detect soccer specific differences in the fitness of soccer players. In conclusion, the research has demonstrated that gas exchange kinetics test has limited use for the identification of aerobic fitness in elite athletes. Future investigations might clarify the relationship between the soccer specific fitness test and match performance

Gas exchange kinetics in elite runners.

Oxygen uptake (VO[2]) kinetics measured in the frequency domain are known to be faster in subjects of greater aerobic fitness (Essfeld et al. 1987). Carbon dioxide output (VCO[2] ) kinetics have been shown to be delayed following 6 months sprint and strength training in footballers (Fukuoka et al 1997) and might also, therefore, be expected to differentiate subjects according to their aerobic fitness. The purpose of this study was to examine whether an established technique for measuring gas exchange kinetics could be applied as a test to differentiate between elite athletic groups. The subject groups selected for this study were 12 elite male sprinters (ST) and 12 elite male endurance runners (ET). A 300s pseudo random binary sequence (PRBS) exercise protocol was selected to investigate differences between ST and ET. Oxygen uptake (ml-min[-1]) and VCO[2] (ml-min[-1]) were measured on a breath-by-breath basis using a Marquette MGA 1100 respiratory mass spectrometer system. The test/retest reliability of the selected test procedure was examined by the limits of agreement technique. Ten healthy male subjects agreed to participate in the reliability study and all subjects completed 3 consecutive 300s PRBS cycles with 20 s work rate changes between 25 and 85 W on an electrically-braked cycle ergometer at a pedal cadence of 1 Hz. Fourier analysis was computed for frequencies 3.3, 6.7 and 10 mHz. The limits of agreement between test and retest were closer at each measured frequency of VO[2] kinetics than VCO[2] kinetics. The measurement error for VO[2] kinetics ranged from 18-35%, while VCO[2] kinetics displayed greater variability, ranging from 39 - 108%. The results of the reliability study suggest that, using the selected test procedure, VO[2] kinetics are more likely to detect physiological differences between ET and ST than VCO[2] kinetics.In the study of elite athletes, twelve elite male sprinters and twelve elite endurance runners completed the selected PRBS exercise test. Blood lactate concentrations taken pre and post testing remained below 2mM. Statistical analysis by two way ANOVA with repeated measures and tukey honest significant difference post hoc test showed significantly greater amplitude ratios for ET than ST at frequencies 6.7mHz (6.71 +/-1.09 and 5.47 +/-0.95 ml-min[-1]-W[-1]respectively) P<0.05) and 10 mHz (4.97 +/-0.98 and 3.56 +/-0.69 ml-min[-1]W[-1] respectively) (P<0.01) for VO[2] kinetics but not for VCO[2] kinetics. Significantly shorter phase shifts were observed for ET than ST at frequency 3.3mHz (-35.45 +/-4.31 and -41.26 +/-5.82 degrees respectively) (P<0.05) for VO[2] kinetics but not for VCO[2] kinetics, although a trend for faster VCO[2] kinetics was evident in ET. The findings of this study show that VO[2] kinetics and not VCO[2] kinetics, as measured by the selected PRBS test, differentiate between elite sprinters and endurance runners. This supports the further development of the VO[2] kinetics test as a practical measure to differentiate between sports groups

Numerosity and density judgments: Biases for area but not for volume

International audienceHuman observers can rapidly judge the number of items in a scene. This ability is underpinned by specific mechanisms encoding number or density. We investigated whether judgments of number and density are biased by a change in volume, as they are by a change in area. Stimuli were constructed using nonoverlapping black and white luminance-defined dots. An eight-mirror Wheatstone stereoscope was used to present the dots as though in a volume. Using a temporal two-alternative forced-choice (2AFC) task and the Method of Constant Stimuli (MOCS), we measured the precision and bias (PSE shift) of numerosity and density judgments, separately, for stimuli differing in area or volume. For two-dimensional (2-D) stimuli, consistent with previous literature, perceived density was biased as area increased. However, perceived number was not. For three-dimensional (3-D) stimuli, despite a vivid impression of the dots filling a cylindrical volume, there was no bias in perceived density or number as volume increased. A control experiment showed that all of our observers could easily perceive disparity in our stimuli. Our findings reveal that number and density judgments that are biased by area are not similarly biased by volume changes

Pacing behaviour development and acquisition: A systematic review

The goal-directed decision-making process of effort distribution (i.e. pacing) allows individuals to efficiently use energy resources as well as to manage the impact of fatigue on performance during exercise. Given the shared characteristics between pacing behaviour and other skilled behaviour, it was hypothesized that pacing behaviour would adhere to the same processes associated with skill acquisition and development. PubMed, Web of Science and PsycINFO databases between January 1995 and January 2022 were searched for articles relating to the pacing behaviour of individuals (1) younger than 18 years of age, or (2) repeatedly performing the same exercise task, or (3) with different levels of experience. The search resulted in 64 articles reporting on the effect of age (n = 33), repeated task exposure (n = 29) or differing levels of experience (n = 13) on pacing behaviour. Empirical evidence identifies the development of pacing behaviour starts during childhood (~ 10 years old) and continues throughout adolescence. This development is characterized by an increasingly better fit to the task demands, encompassing the task characteristics (e.g. duration) and environment factors (e.g. opponents). Gaining task experience leads to an increased capability to attain a predetermined pace and results in pacing behaviour that better fits task demands. Similar to skilled behaviour, physical maturation and cognitive development likely drive the development of pacing behaviour. Pacing behaviour follows established processes of skill acquisition, as repeated task execution improves the match between stimuli (e.g. task demands and afferent signals) and actions (i.e. continuing, increasing or decreasing the exerted effort) with the resulting exercise task performance. Furthermore, with increased task experience attentional capacity is freed for secondary tasks (e.g. incorporating opponents) and the goal selection is changed from achieving task completion to optimizing task performance. As the development and acquisition of pacing resemble that of other skills, established concepts in the literature (e.g. intervention-induced variability and augmented feedback) could enrich pacing research and be the basis for practical applications in physical education, healthcare, and sports. [Abstract copyright: © 2022. The Author(s).

Effects of Experience and Opponents on Pacing Behavior and 2-km Cycling Performance of Novice Youths

Purpose: To study the pacing behavior and performance of novice youth exercisers in a controlled laboratory setting. Method: Ten healthy participants (seven male, three female, 15.8 ± 1.0 years) completed four, 2-km trials on a Velotron cycling ergometer. Visit 1 was a familiarization trial. Visits 2 to 4 involved the following conditions, in randomized order: no opponent (NO), a virtual opponent (starting slow and finishing fast) (OP-SLOWFAST), and a virtual opponent (starting fast and finishing slow) (OP-FASTSLOW). Repeated measurement ANOVAs (p .05). Conclusion: Performance was improved by an increase in experience after one visit, parallel with the ability to anticipate future workload

Involving older adults in the technology design process: : a case study on mobility and wellbeing in the built environment

Older adults benefit from unstructured, lifestyle-based activity that can be carried out in people’s houses, neighbourhoods, and the built environment. Technological solutions may support physical activity and encourage wellbeing. To ensure such technology is suitable for, and usable by, older adults, it is crucial they are involved in all stages of design. Participatory design methodologies facilitate collaboration and engagement with potential users. We examine the suitability of participatory design for collaborating and engaging with older adults. Participatory design workshops were conducted with 33 older adults in the UK with the aim of designing mobile applications to support and promote physical activity and wellbeing in the built environment. As well as summarising the outcome of these workshops, the paper outlines several methodological issues relating to the suitability of participatory design for involving older adults in the technology design proces

“Unfortunately, I use my car”: Commuter transport choices in Bristol, UK

© 2018 WIT Press. The leading source of nitrogen dioxide (NO2) concentrations in Bristol, United Kingdom is road transport, and Bristol exceeds the annual mean national air quality objective of 40 µg/m3 for NO2 in many locations around the city. Understanding the reasons for residents' modal choice is an important element in managing air quality in the city. The ClairCity Project approach provides insight into how to reduce overall transport demand and identify incentives that will be effective in creating modal switch away from higher polluting private motorised vehicles. From the ClairCity Project survey subset of commuters (n=442), 45% of respondents used cars or vans at least occasionally for their journey to work, with 28% of the total number of commuters relying exclusively on private motorised transport. The majority of these car users (65.6%) said they would prefer not to travel by car to work in the future. Their responses showed a mix of negative perceptions of public transport, geography and health as key motivations. Family responsibilities, lack of safe cycling and walking spaces, poor health and disability, distance, requirements to transport goods as well as themselves and the need for flexibility were all given as barriers to modal switching. This suggests that for car commuters, well-targeted policy interventions could provide practical alternatives that would appeal to those who currently rely on private motorised transport. Understanding citizens' perceptions, behaviours and activities is a key element in decision-making to reduce transport related air quality emissions and concentrations

Applying Adverse Outcome Pathways (AOPs) to support Integrated Approaches to Testing and Assessment (IATA)

Chemical regulation is challenged by the large number of chemicals requiring assessment for potential human health and environmental impacts. Current approaches are too resource intensive in terms of time, money and animal use to evaluate all chemicals under development or already on the market. The need for timely and robust decision making demands that regulatory toxicity testing becomes more cost-effective and efficient. One way to realize this goal is by being more strategic in directing testing resources; focusing on chemicals of highest concern, limiting testing to the most probable hazards, or targeting the most vulnerable species. Hypothesis driven Integrated Approaches to Testing and Assessment (IATA) have been proposed as practical solutions to such strategic testing. In parallel, the development of the Adverse Outcome Pathway (AOP) framework, which provides information on the causal links between a molecular initiating event (MIE), intermediate key events (KEs) and an adverse outcome (AO) of regulatory concern, offers the biological context to facilitate development of IATA for regulatory decision making. This manuscript summarizes discussions at the Workshop entitled “Advancing AOPs for Integrated Toxicology and Regulatory Applications” with particular focus on the role AOPs play in informing the development of IATA for different regulatory purposes.publishedVersio

Novel Approach to Estimate Osteoarthritis Progression:Use of the Reliable Change Index in the Evaluation of Joint Space Loss

OBJECTIVE: Osteoarthritis-related changes in joint space measurements over time are small and sensitive to measurement error. The Reliable Change Index (RCI) determines whether the magnitude of change observed in an individual can be attributed to true change. This study aimed to examine the RCI as a novel approach to estimating osteoarthritis progression.METHODS: Data were from 167 men and 392 women with knee osteoarthritis (diagnosed using the American College of Rheumatology criteria) randomized to the placebo arm of the 3-year Strontium Ranelate Efficacy in Knee Osteoarthritis trial (SEKOIA) and assessed annually. The RCI was used to determine whether the magnitude of change in joint space width (JSW) on radiographs between study years was likely to be true or due to measurement error.RESULTS: Between consecutive years, 57-69% of participants had an apparent decrease (change &lt;0) in JSW, while 31-43% of participants had annual changes indicating improvement in JSW. The RCI identified JSW decreases in only 6.0% of patients between baseline and year 1, and in 4.5% of patients between the remaining study years. The apparent increases in JSW were almost eliminated between baseline and year 1, and between years 1 and 2 only 1.3% of patients had a significant increase, dropping to 0.9% between years 2 and 3.CONCLUSION: The RCI provides a method to identify change in JSW, removing many apparent changes that are likely to be due to measurement error. This method appears to be useful for assessing change in JSW from radiographs in clinical and research settings.</p