Medical consequences in endurance sports - Two Oceans Marathon longitudinal study : an evaluation of participation guidelines in runners presenting with symptoms of acute illness before competition

Includes bibliographical references.Background: One of the most common clinical decisions a Sports and Exercise Medicine (SEM) physician is required to make is whether an athlete presenting with symptoms or signs of an acute illness can participate in exercise training or competition. Currently, a clinical tool, known as the ‘neck check’ is used to determine eligibility to participate in exercise training or competition athletes with acute illness. This original clinical tool, first described about 20 years ago, was based mainly on an abbreviated medical history and findings of a clinical examination were excluded. Symptoms of illness ‘above-the-neck’ e.g.sneezing, rhinorrhoea or sinus congestion constitute a ‘passed’ “neck check”, whereas ‘below-the-neck’ symptoms e.g.cough and/or systemic symptoms such as fever and myalgia, constitute a ‘failed’ “neck check”. However, in the current literature, there remain very few data regarding 1) the adherence of athletes to advice given following a ‘neck check’, and 2) whether the exercise performance (e.g.the ability to finish a race) or the development of medical complications during exercise is different in athletes who “passed” or “failed” the ‘neck check’. Objective The main objectives of this dissertation are: 1) to review the available evidence with respect to medical assessment and participation risk in endurance runners presenting with symptoms of acute illness before a road race; 2) to document the range of acute illnesses in runners presenting in the 3 days before a race; 3) to determine adherence to advice given by medical staff to these runners, and 4) to determine the effects of the outcomes of the medical assessment on running performance particularly, the ability to finish the race and the medical complications experienced during the race. These data are important to improve the medical care of runners (and other athletes) presenting with acute illness before training and competition. Methods: Phase 1: Review of the literature All literature relating to the epidemiology of acute illness in athletes, risk factors for illness, and participation risk, potential medical complications and effects on performance of exercising whilst ill were sourced using established electronic databases (PubMed, Medline, Google Scholar). In addition, literature related to the background of the ‘neck check’, as well as the evolution of the current RTP guidelines in athletes with acute illness were sourced. Phase 2: Research study In a prospective cohort study, 242 runners who presented to a pre-race registration medical facility with medical concerns were assessed by SEM physicians by means of medical history and physical examination (if indicated) using a specific Pre-Race acute Illness Medical Assessment (PRIMA group). 172 of these runners had evidence suggesting acute infective illness (PRIMA-I group) and 70 runners had non-infective complaints (PRIMA-N/I group). The epidemiology (prevalence rate = % runners) of runners with symptoms, signs and specific clinical diagnoses of acute illnesses were documented in the PRIMA-I group. Following clinical evaluation, all the runners in the PRIMA-I group were then advised regarding clearance to run the race, monitoring symptoms, or not running the race, using the ‘neck check’ as a guideline. Runners in the PRIMA cohort were then tracked during and immediately after the race, and the following parameters were compared to those in a control group of runners not presenting to the medical facility at registration (CON=53 734): 1) incidence of not starting of the race (per 1000 runners) (DNS rate), 2) incidence of not finishing the race in those who started (per 1000 runners) (DNF rate), and 3) incidence of medical complications during the race in those who started (per 1000 runners) (MC rate). Results Phase 1: Review The main finding of the review is the relative paucity in clinical data with respect to participation in athletes with acute illness. Upper respiratory tract symptoms are very common in athletes, and the risk factors are discussed. Furthermore, there are different aetiologies underlying athletes’ URT symptoms (other than infection). The documented risks of exercising when systemically ill include sudden cardiac death and reduced pulmonary function, splenic rupture in patients with infectious mononucleosis, and dehydration and electrolyte disturbances when exercising with acute gastro-intestinal illness. There is little evidence in the literature regarding the effects of illness on performance; these include reduced performance, non-participation and the potential effects of WARI (wheezing after respiratory tract infection). Evidence supporting the two aspects of the neck check is reviewed: the presumed safety of exercising with localised URT symptoms, and the perceived risk of exercising with lower respiratory tract or systemic symptoms. Clinical data are severely lacking, and the available data are based on self-reported symptomatology. There are no published data regarding the use of the ‘neck check’ as a participation guideline. Phase 2: In the PRIMA-I cohort of 172 runners, the most common symptoms were sinus congestion (40.1%), cough (38.2%), sore throat (37.8%) and runny nose (25.6%). More than half the cohort (57.5%) had a diagnosis of localised URTI. However, URTI with generalised symptoms was the single most common diagnosis (22.7%). In the PRIMA-I group, 41.3% of the runners failed the ‘neck check’. Compared with the CON group, there was no significant difference in the DNS rate in the PRIMA-I group. However, in those runners who were advised not to run, the DNS rate was 565 per 1000 runners, and this was significantly higher than that of the CON group (192 per 1000 runners) (p<0.0001). PRIMA-I race starters had a higher DNF rate (31 per 1000 runners), and runners with any medical concerns (PRIMA group) had a significantly higher DNF rate (37 per 1000 runners) compared to the CON group of runners who started the race (15 per 1000 runners) (p= 0.0329). There were no documented medical complications in the PRIMA-I group who started the race, while the MC rate of the CON group was 6.7 per 1000 runners. In runners in the PRIMA-I group who had been advised not to run, 43.5% were non-adherent, and started the race despite this advice. Conclusion: Our study indicates that localised upper respiratory tract infection is responsible for the majority of acute illness in a pre-race cohort of runners. Furthermore, the data provide some evidence that it is safe for runners with acute illness to exercise if they pass the ‘neck check’. However, presenting to a pre-race registration medical facility, failing the ‘neck check’ and receiving advice against participation appear to increase the risk of not finishing a race. There is also concern about the high rate of non-adherence to advice given by the SEM physician. Finally, a pre-race registration medical assessment for runners with acute illness may reduce the risk of developing short-term medical complications during the race

Harmonic analysis of lossy piezoelectric composite transducers using the plane wave expansion method

Periodic composite ultrasonic transducers oer many advantages but the periodic pillar architecture can give rise to unwanted modes of vibration which interfere with the piston like motion of the fundamental thickness mode. In this paper, viscoelastic loss is incorporated into a three dimensional plane wave expansion model (PWE) of these transducers. A comparison with experimental and nite element data is conducted and a design to damp out these lateral modes is investigated. Scaling and regularisation techniques are introduced to the PWE method to reduceill-conditioning in the large matrices which can arise. The identication of the modes of vibration is aided by examining proles of the displacements, electrical potentialand Poynting vector. The dispersive behaviour of a 2-2 composite transducer with high shear attenuation in the passive phase is examined. The model shows thatthe use of a high shear attenuation ller material improves the frequency band gap surrounding the fundamental thickness mode

A New Velocity Map for Byrd Glacier, East Antarctica, from Sequential Aster Satellite Imagery

New ice-velocity measurements are obtained for the main trunk of Byrd Glacier, East Antarctica, using recently acquired Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) imagery. The velocities are derived from the application of a cross-correlation technique to sequential images acquired in 2000 and 2001. Images were co-registered and ortho-rectified with the aid of a digital elevation model (DEM) generated from ASTER stereo imagery. This paper outlines the process of DEM generation, image co-registration and correction, and the application of the cross-correlation technique to obtain ice velocities. Comparison of the new velocity map with earlier measurements of velocity from 1978 indicates that the glacier has undergone a substantial deceleration between observations. Portions of the glacier flowing at speeds of similar to 850 m a(-1) in 1978/79 were flowing at similar to 650 m a(-1) in 2000/01. The cause of this change in ice dynamics is not known, but the observation shows that East Antarctic outlet glaciers can undergo substantial changes on relatively short timescales

Impact of ocean stratification on submarine melting of a major Greenland outlet glacier

Submarine melting is an important balance term for tidewater glaciers1,2 and recent observations point to a change in the submarine melt rate as a potential trigger for the widespread acceleration of outlet glaciers in Greenland3-5. Our understanding of the dynamics involved, and hence our ability to interpret past and predict future variability of the Greenland Ice Sheet, however, is severely impeded by the lack of measurements at the ice/ocean interface. To fill this gap, attempts to quantify the submarine melt rate and its variability have relied on a paradigm developed for tidewater glaciers terminating in fjords with shallow sills. In this case, the fjords&#x2019; waters are mostly homogeneous and the heat transport to the terminus, and hence the melt rate, is controlled by a single overturning cell in which glacially modified water upwells at the ice edge, driving an inflow at depth and a fresh outflow at the surface1. Greenland&#x2019;s fjords, however, have deep sills which allow both cold, fresh Arctic and warm, salty Atlantic waters, circulating around Greenland, to reach the ice sheet margin3,6,7. Thus, Greenland&#x2019;s glaciers flow into strongly stratified fjords and the generic tidewater glacier paradigm is not applicable. Here, using new summer data collected at the margins of Helheim Glacier, East Greenland, we show that melting is driven by both Atlantic and Arctic waters and that the circulation at the ice edge is organized in multiple, overturning cells that arise from their different properties. Multiple cells with different characteristics are also observed in winter, when glacial run off is at a minimum and there is little surface outflow. These results indicate that stratification in the fjord waters has a profound impact on the melting dynamics and suggest that the shape and stability of Greenland&#x2019;s glaciers are strongly influenced by layering and variability in the Arctic and Atlantic waters. &#xd;&#xa;&#xd;&#xa

Rapid volume loss from two East Greenland outlet glaciers quantified using repeat stereo satellite imagery

This is the publisher's version, also available electronically from "http://onlinelibrary.wiley.com/".[1] The coastal portions of Kangerdlugssuaq and Helheim glaciers in southeast Greenland lost at least 51 ± 8 km3 yr−1 of ice between 2001–2006 due to thinning and retreat, according to an analysis of sequential digital elevation models (DEMs) derived from stereo ASTER satellite imagery. The dominant contribution to this ice loss was dynamic thinning caused by the acceleration in flow of both glaciers. Peak rates of change, including thinning rates of ∼90 m yr−1, coincided with the rapid increases in flow speed. Extrapolation of the measured data to the ice divides yields an estimated combined catchment volume loss of ∼122 ± 30 km3 yr−1, which accounts for half the total mass loss from the ice sheet reported in recent studies. These catchment-wide volume losses contributed ∼0.31 ± 0.07 mm yr−1 to global sea level rise over the 5-year observation period with the coastal regions alone contributing at least 0.1 ± 0.02 mm yr−1

Rapid Volume Loss from Two East Greenland Outlet Glaciers Quantified Using Repeat Stereo Satellite Imagery

The coastal portions of Kangerdlugssuaq and Helheim glaciers in southeast Greenland lost at least 51 +/- 8 km(-3) yr(-1) of ice between 2001-2006 due to thinning and retreat, according to an analysis of sequential digital elevation models (DEMs) derived from stereo ASTER satellite imagery. The dominant contribution to this ice loss was dynamic thinning caused by the acceleration in flow of both glaciers. Peak rates of change, including thinning rates of similar to 90 m yr(-1), coincided with the rapid increases in flow speed. Extrapolation of the measured data to the ice divides yields an estimated combined catchment volume loss of similar to 122 +/- 30 km(-3) yr(-1), which accounts for half the total mass loss from the ice sheet reported in recent studies. These catchment-wide volume losses contributed similar to 0.31 +/- 0.07 mm yr(-1) to global sea level rise over the 5-year observation period with the coastal regions alone contributing at least 0.1 +/- 0.02 mm yr(-1)

Sex, Drugs, and Rock \u27n\u27 Roll: What Shall We Ban Next?

Music, literature, movies, and all forms of entertainment play an important role in the socialization of adolescents. Present everywhere and easily available, this allows children almost limitless access to questionable entertainment alone or with friends. Parents are unaware of the content of what their children are absorbing because of the use of downloaded music, videos, and literature, and the use of headphones. Research on popular culture/entertainment has explored its effects on schoolwork, social interactions, and particularly behavior. Lyrics have become more explicit in their references to drugs, sex, and violence over the years, particularly in certain genres. And, in turn, there have been myriad attempts to censor, ban, and block access to various materials. Justifications for such efforts has been the belief that a teenager\u27s preference for certain types of entertainment could be correlated or associated with certain behaviors. The purpose of this chapter is to offer an historical examination of the efforts to censor and/or ban what children are exposed