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Biomedical subjects

G P Whyte

Publications and source records attributed to G P Whyte.

14 recordsLinked to original sources
PubMed2006

Breathless in the bath.

The case is reported of a male track and field athlete with breathing difficulties at rest and during exercise, which were exacerbated in the supine position and during water immersion. Right hemidiaphragmatic paralysis was diagnosed. The cause of this relatively benign disorder is not known and there are no serious clinical implications. There is no treatment, but a continuation of exercise together with interventions to strengthen the subsidiary inspiratory muscles is recommended.

Adult↗
PubMed2006

Screening elite winter athletes for exercise induced asthma: a comparison of three challenge methods.

BACKGROUND: The reported prevalence of exercise induced asthma (EIA) in elite winter athletes ranges from 9% to 50%. Many elite winter athletes do not report symptoms of EIA. At present there is no gold standard test for EIA. OBJECTIVE: To establish the efficacy of screening for EIA and examine the role of the eucapnic voluntary hyperventilation (EVH) challenge and laboratory based and sport specific exercise challenges in the evaluation of elite winter athletes. METHODS: 14 athletes (mean (SD) age 22.6 (5.7) years, height 177.2 (7.0) cm, body mass 68.9 (16.9) kg) from the Great Britain short-track speed skating (n = 10) and biathlon teams (n = 4) were studied. Each athlete completed a laboratory based and sport specific exercise challenge as well as an EVH challenge, in randomised order. RESULTS: All 14 athletes completed each challenge. Two had a previous history of asthma. Ten (including the two with a previous history) had a positive test to at least one of the challenges. Ten athletes had a positive response to EVH; of these, only three also had a positive response to the sport specific challenge. No athletes had a positive response to the laboratory based challenge. CONCLUSIONS: Elite athletes should be screened for EIA. EVH is a more sensitive challenge in asymptomatic athletes than sport specific and laboratory based challenges. If sporting governing bodies were to implement screening programmes to test athletes for EIA, EVH is the challenge of choice.

Adolescent↗
PubMed2005

Mid-expiratory flow versus FEV1 measurements in the diagnosis of exercise induced asthma in elite athletes.

BACKGROUND: A fall in FEV(1) of > or =10% following bronchoprovocation (eucapnic voluntary hyperventilation (EVH) or exercise) is regarded as the gold standard criterion for diagnosing exercise induced asthma (EIA) in athletes. Previous studies have suggested that mid-expiratory flow (FEF(50)) might be used to supplement FEV(1) to improve the sensitivity and specificity of the diagnosis. A study was undertaken to investigate the response of FEF(50) following EVH or exercise challenges in elite athletes as an adjunct to FEV(1). METHODS: Sixty six male (36 asthmatic, 30 non-asthmatic) and 50 female (24 asthmatic, 26 non-asthmatic) elite athletes volunteered for the study. Maximal voluntary flow-volume loops were measured before and 3, 5, 10, and 15 minutes after stopping EVH or exercise. A fall in FEV(1) of > or =10% and a fall in FEF(50) of > or =26% were used as the cut off criteria for identification of EIA. RESULTS: There was a strong correlation between DeltaFEV(1) and DeltaFEF(50) following bronchoprovocation (r = 0.94, p = 0.000). Sixty athletes had a fall in FEV(1) of > or =10% leading to the diagnosis of EIA. Using the FEF(50) criterion alone led to 21 (35%) of these asthmatic athletes receiving a false negative diagnosis. The lowest fall in FEF(50) in an athlete with a > or =10% fall in FEV(1) was 14.3%. Reducing the FEF(50) criteria to > or =14% led to 13 athletes receiving a false positive diagnosis. Only one athlete had a fall in FEF(50) of > or =26% in the absence of a fall in FEV(1) of > or =10% (DeltaFEV(1) = 8.9%). CONCLUSION: The inclusion of FEF(50) in the diagnosis of EIA in elite athletes reduces the sensitivity and does not enhance the sensitivity or specificity of the diagnosis. The use of FEF(50) alone is insufficiently sensitive to diagnose EIA reliably in elite athletes.

Adult↗
PubMed2005

The detraining and retraining of an elite rower: a case study.

A heavyweight male rower, and current Olympic champion, undertook a laboratory-based incremental rowing test on four separate occasions; eight weeks prior to the Sydney Olympics (Pre OG), after eight weeks of inactivity (Post-IA), after 8 weeks of retraining (Post 8) and after a further 12 weeks of training (Post 20). Following the period of inactivity, peak oxygen uptake (VO2peak) declined by 8%, power at reference blood lactate concentrations declined by approximately 100 W (25%), and power at VO2peak was 20% lower. With eight weeks of retraining, rapid improvements were seen. For most parameters, however, the rate of improvement slowed and after 20 weeks of retraining the individual was approaching pre-Olympic levels. VO2 at lactate threshold as a percentage of VO2peak remained unchanged. These results show that detraining in the elite athlete can be pronounced, with rapid improvements upon retraining which slow, so that retraining takes considerably longer to achieve than detraining did. Complete cessation of training should be limited to short periods only in the preparation of the elite heavyweight rower. Any break should, if possible, include 'maintenance training'. In this way any decrements in those physiological parameters associated with 2000 m rowing performance will be minimised.

Body Mass Index↗
PubMed2005

Impact of changes in the IOC-MC asthma criteria: a British perspective.

BACKGROUND: Since 2001 the International Olympic Committee-Medical Commission (IOC-MC) has required athletes using inhaled beta2 agonists to provide clinical evidence of their asthmatic condition. The aim of this study was to compare the reported prevalence of asthma at the 2000 and 2004 Olympic Games in the Great British Olympic team (Team GB). METHODS: Following local ethics committee approval, 271 athletes (165 men) from the 2004 Team GB volunteered and provided written informed consent. An athlete was confirmed asthmatic if he or she had a positive bronchoprovocation or bronchodilator test as defined by the IOC-MC. Pre-Olympic medical forms from the 2000 Team GB were also examined to establish the prevalence of asthma among the members of Team GB at the 2000 Olympic Games. RESULTS: The prevalence of asthma in the two teams at the 2000 and 2004 Olympic Games was similar (21.2% and 20.7%, respectively). In the 2004 Olympic Games 13 of 62 athletes (21.0%) with a previous diagnosis of asthma tested negative. A further seven with no previous diagnosis of asthma tested positive. CONCLUSIONS: The prevalence of asthma within Team GB remained unchanged between 2000 and 2004. The IOC-MC requirement that asthmatic athletes must submit documented evidence of asthma has highlighted that 13 (21.0%) previously diagnosed as asthmatic failed to demonstrate evidence of asthma while seven athletes with no previous history or diagnosis of asthma tested positive. Screening for asthma within elite athletic populations using bronchoprovocation challenges appears warranted to assist athletes in preparing more effectively for major sporting events.

Asthma↗
PubMed2004

The upper limit of physiological cardiac hypertrophy in elite male and female athletes: the British experience.

Establishment of upper normal limits of physiological hypertrophy in response to physical training is important in the differentiation of physiological and pathological left ventricular hypertrophy. The genetic differences that exist in the adaptive response of the heart to physical training and the causes of sudden cardiac death in young athletes indicate the need for population-specific normal values. Between September 1994 and December 2001, 442 (306 male, 136 female) elite British athletes from 13 sports were profiled. Standard two-dimensional guided M-mode and Doppler echocardiography were employed to evaluate left ventricular morphology and function. Eleven (2.5%) athletes, competing in a range of sports including judo, skiing, cycling, triathlon, rugby and tennis, presented with a wall thickness >13 mm, commensurate with a diagnosis of hypertrophic cardiomyopathy. Eighteen (5.8%) male athletes presented with a left ventricular internal diameter during diastole (LVIDd) >60 mm, with an upper limit of 65 mm. Of the 136 female athletes, none where found to have a maximum wall thickness >11 mm. Left ventricular internal diameter was <60 mm in all female athletes. Systolic and diastolic function were within normal limits for all athletes. Upper normal limits for left ventricular wall thickness and LVIDd are 14 mm and 65 mm for elite male British athletes, and 11 mm and 60 mm for elite female British athletes. Values in excess of these should be viewed with caution and should prompt further investigation to identify the underlying mechanism.

Adolescent↗
PubMed2004

Left ventricular morphology and function in female athletes: a meta-analysis.

The purpose of the present study was to examine the impact of physical training upon cardiac structure and function, and identify physiologic upper limits in female athletes. Meta-analytical techniques were applied to 13 published echocardiographic studies examining cardiac structure and function in female athletes. The study group included 890 athletes and 333 controls. For comparison of sporting discipline, studies were partitioned into 3 categories (endurance, strength/sprint, team). Significant (p < 0.05) effect sizes were observed for all structural measures between athletes and controls. Significant effect size differences existed between sporting groups for LVIDd and LVM only, with endurance and team game athletes demonstrating the largest effect sizes compared to strength trained athletes. No significant effect of training was observed for left ventricular diastolic or systolic function, with the exception of stroke volume where a significant effect size difference was observed between athletes and controls with no observed difference between sporting groups. Maximum reported upper limits for LV wall thickness and LVIDd in female athletes were 12 mm and 66 mm respectively. Chronic exercise training results in cardiac enlargement in female athletes. The nature of physiologic adaptation is similar to that observed in male athletes. LV wall thickness values greater than 12 mm in female athletes should be viewed with caution and indicate a more comprehensive evaluation to establish a physiological or pathological basis for the observed left ventricular enlargement.

Adaptation, Physiological↗
PubMed2002

Determinants of 2,000 m rowing ergometer performance in elite rowers.

This study examined the physiological determinants of performance during rowing over 2,000 m on an ergometer in finalists from World Championship rowing or sculling competitions from all categories of competion rowing (19 male and 13 female heavyweight, 4 male and 5 female lightweight). Discontinuous incremental rowing to exhaustion established the blood lactate threshold, maximum oxygen consumption (VO(2max)) and power at VO(2max); five maximal strokes assessed maximal force, maximal power and stroke length. These results were compared to maximal speed during a 2,000 m ergometer time trial. The strongest correlations were for power at VO(2max), maximal power and maximal force (r=0.95; P<0.001). Correlations were also observed for VO(2max) (r=0.88, P<0.001) and oxygen consumption (VO(2)) at the blood lactate threshold (r=0.87, P=0.001). The physiological variables were included in a stepwise regression analysis to predict performance speed (metres per second). The resultant model included power at VO(2max), VO(2) at the blood lactate threshold, power at the 4 mmol x l(-1) concentration of blood lactate and maximal power which together explained 98% of the variance in the rowing performance over 2,000 m on an ergometer. The model was validated in 18 elite rowers, producing limits of agreement from -0.006 to 0.098 m x s(-1) for speed of rowing over 2,000 m on the ergometer, equivalent to times of -1.5 to 6.9 s (-0.41% to 1.85%). Together, power at VO(2max), VO(2) at the blood lactate threshold, power at 4 mmol x l(-1) blood lactate concentration and maximal power could be used to predict rowing performance.

Adult↗
PubMed2001

Comparison of physiological responses to morning and evening submaximal running.

The aim of this study was to assess the effect of time of day on physiological responses to running at the speed at the lactate threshold. After determination of the lactate threshold, using a standard incremental protocol, nine male runners (age 26.3 +/- 5.7 years, height 1.77 +/- 0.07 m, mass 73.1 +/- 6.5 kg, lactate threshold speed 13.6 +/- 1.6 km x h(-1); mean +/- s) completed a standardized 30 min run at lactate threshold speed, twice within 24 h (07:00-09:00 h and 18:00-21:00 h). Core body temperature, heart rate, minute ventilation, oxygen uptake, carbon dioxide expired, respiratory exchange ratio and capillary blood lactate were measured at rest, after a warm-up and at 10, 20 and 30 min during the run. In addition, the rating of perceived exertion was reported every 10 min during the run. Significant diurnal variation was observed only for body temperature (36.9 +/- 0.9 degrees C vs 37.3 +/- 0.3 degrees C) and respiratory exchange ratio at rest (0.86 +/- 0.01 vs 0.89 +/- 0.07) (P < 0.05). Diurnal variation persisted for body temperature throughout the warm-up (37.1 +/- 0.2 degrees C vs 37.5 +/- 0.3 degrees C) and during exercise (36.2 +/- 0.6 degrees C vs 38.6 +/- 0.4 degrees C), but only during the warm-up for the respiratory exchange ratio (0.85 +/- 0.05 vs 0.87 +/- 0.02) (P < 0.05). The rating of perceived exertion was significantly elevated during the morning trial (12.7 +/- 0.9 vs 11.9 +/- 1.2) (P < 0.05). These findings suggest that, despite the diurnal variation in body temperature, other physiological responses to running at lactate threshold speed are largely unaffected. However, a longer warm-up may be required in morning trials because of a slower increase in body temperature, which could have an impact on ventilation responses and ratings of perceived exertion.

Adult↗
PubMed2001

Stability of psychometric questionnaires.

In 1999, Wilson and Batterham proposed a new approach to assessing the test-retest stability of psychometric questionnaires. They recommended assessing the proportion of agreement - that is, the proportion of participants that record the same response to an item - using a test-retest design. They went on to use a bootstrapping technique to estimate the uncertainty of the proportion of agreement. The aims of this short communication are (1) to demonstrate that the sampling distribution of the proportion of agreement is well known (the binomial distribution), making the technique of 'bootstrapping' redundant, and (2) to suggest a much simpler, more sensitive method of assessing the stability of a psychometric questionnaire, based on the test-retest differences (within-individuals) for each item. Adopting methods similar to Wilson and Batterham, 97 sport students completed the Social Physique Anxiety Scale on two occasions. Test-retest differences were calculated for each item. Our results show that the proportion of agreement ignores the nature of disagreement. Items 4 and 11 showed similar agreement (44.3% and 43.3% respectively), but 89 of the participants (91.8%) differed by just +/-1 point when responding to item 4, indicating a relatively stable item. In contrast, only 78 of the participants (80.4%) recorded a difference within +/- 1 point when responding to item 11, suggesting quite contrasting stability for the two items. We recommend that, when assessing the stability of self-report questionnaires using a 5-point scale, most participants (90%) should record test-retest differences within a reference value of +/- 1.

Adult↗
PubMed2000

Comparison of critical swimming velocity and velocity at lactate threshold in elite triathletes.

The purpose of this study was to determine whether the critical swimming velocity (Vcrit) corresponds to the velocity at lactate threshold (V-LT) in elite triathletes. Eight elite triathletes (5 male, 3 female; age 26 +/- 4 years; height 1.7 +/- 0.1 m and body mass 75 +/- 4 kg) participated in the study. Vcrit, defined as the speed that could theoretically be maintained indefinitely without exhaustion, was expressed as the slope of a regression line between swimming distance covered and the corresponding times of five time trials over 100, 200, 400, 800 and 1500m and all combinations of these. Lactate threshold (LT) was determined by visual inspection as the point of first inflection of the lactate-work rate curve following 5 x 300 m swims of increasing velocity which were paced using the Aquapacer (Challenge and Response, Inverurie, Scotland). Velocities of the 300 m swims were -10, -5, 0, +5 and +10% of the average 100m pace from a 1500 m time trial. Vcrit was similar regardless of the combination or number of time trials used in the linear regression. For all subjects Vcrit was significantly faster (p <0.05) than V-LT (1.23 +/- 0.11 m x s(-1) and 1.15 +/- 0.10 m x s(-1) respectively). Blood lactate concentrations were also significantly higher (p < 0.05) at Vcrit (3.0 +/- 1.0 mM) than at LT (1.9 +/- 0.4 mM). Results from the present study demonstrate that Vcrit can be calculated from any two time trials in triathletes, however Vcrit did not represent V-LT in triathletes. Since Vcrit is faster than V-LT it is unlikely to be sustained indefinitely and consequently the notion of Vcrit should be re-evaluated in light of these findings.

Adult↗
PubMed2000

Cardiac fatigue following prolonged endurance exercise of differing distances.

PURPOSE: Recent echocardiographic studies have reported cardiac dysfunction following ultra-endurance exercise in trained individuals. The duration of exercise required to elicit cardiac dysfunction and the mechanisms underlying this phenomenon have not been fully elucidated. The aim of the present study was to examine the presence of cardiac dysfunction following a half-Ironman and Ironman triathlon in trained individuals. METHODS: 14 male triathletes (age: 32 +/- 5 yr; height: 180 +/- 8 cm; body mass: 75 +/- 9 kg) completed a half-Ironman triathlon. Following a 4-wk period, 10 of the original 14 triathletes completed an Ironman triathlon. All triathletes were assessed using ECG, echocardiography, and blood analysis pre-, immediately post-, and 48 h postrace for both distances. RESULTS: Echocardiographic results indicated diastolic and systolic left ventricular dysfunction, for both race distances, which were associated with altered relaxation characteristics and a reduced inotropic contractility, respectively. Following 48-h recovery, all echocardiographic measures were similar to resting values. Creatine kinase MB (CKMB) was significantly elevated immediately postrace for both distances; however, it accounted for less than 5% of the total CK value and in the presence of an elevated total CK and CKMM implied that the elevated CKMB was noncardiac in origin. Troponin-T, however, was significantly elevated immediately postrace for both distances and returned to normal following 48-h recovery indicating myocardial damage. CONCLUSIONS: Ironman and half-Ironman competition resulted in reversible abnormalities in resting left ventricular diastolic and systolic function. Results suggest that myocardial damage may be, in part, responsible for cardiac dysfunction, although the mechanisms responsible for this cardiac damage remain to be fully elucidated.

Adult↗
PubMed1999

Exercise gas exchange responses in the differentiation of pathologic and physiologic left ventricular hypertrophy.

PURPOSE: The purpose of the present investigation was to examine differences that may exist in maximal and submaximal exercise gas exchange parameters and their use in differentiating pathological and physiological left ventricular hypertrophy. METHODS: Exercise gas exchange responses were measured on-line during a maximal ramping cycle-ergometer exercise test in 10 young, male hypertrophic cardiomyopathy (HCM) patients, 11 elite triathletes, and 9 normal controls. RESULTS: The HCM patients exhibited significantly lower VO2max, anaerobic threshold (AT) in both absolute terms (ATVO2) and as a percentage of VO2max (AT%VO2max), and oxygen-pulse (O2-pulse) compared with triathletes and normal controls. Elite triathletes exhibited significantly increased VO2max, %VO2max, ATVO2, AT%VO2max and O2-pulse compared with controls. The VE/VCO2 at AT was significantly increased in the HCM patients compared with triathletes and controls, whereas no difference was observed between triathletes and controls. CONCLUSIONS: Maximal and submaximal exercise gas exchange responses may be used as an additional noninvasive tool in the differential diagnosis of physiologic and pathologic left ventricular hypertrophy.

Adult↗