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Biomedical subjects

D G Rowbottom

Publications and source records attributed to D G Rowbottom.

11 recordsLinked to original sources
PubMed2003

A practical method of estimating energy expenditure during tennis play.

This study aimed to develop a practical method of estimating energy expenditure (EE) during tennis. Twenty-four elite female tennis players first completed a tennis-specific graded test in which five different Intensity levels were applied randomly. Each intensity level was intended to simulate a "game" of singles tennis and comprised six 14 s periods of activity alternated with 20 s of active rest. Oxygen consumption (VO2) and heart rate (HR) were measured continuously and each player's rate of perceived exertion (RPE) was recorded at the end of each intensity level. Rate of energy expenditure (EE(VO2)) during the test was calculated using the sum of VO2 during play and the 'O2 debt' during recovery, divided by the duration of the activity. There were significant individual linear relationships between EE(VO2) and RPE, EE(VO2) and HR (r > or = 0.89 & r > or = 0.93; p < 0.05). On a second occasion, six players completed a 60-min singles tennis match during which VO2, HR and RPE were recorded; EE(VO2) was compared with EE predicted from the previously derived RPE and HR regression equations. Analysis found that EE(VO2) was overestimated by EE(RPE) (92 +/- 76 kJ x h(-1)) and EE(HR) (435 +/- 678 kJ x h(-1)), but the error of estimation for EE(RPE) (t = -3.01; p = 0.03) was less than 5% whereas for EE(HR) such error was 20.7%. The results of the study show that RPE can be used to estimate the energetic cost of playing tennis.

Adolescent↗
PubMed2003

Tennis, incidence of URTI and salivary IgA.

Tennis played at an elite level requires intensive training characterized by repeated bouts of brief intermittent high intensity exercise over relatively long periods of time (1 - 3 h or more). Competition can place additional stress on players. The purpose of this study was to investigate the temporal association between specific components of tennis training and competition, the incidence of upper respiratory tract infections (URTI), and salivary IgA, in a cohort of seventeen elite female tennis players. Timed, whole unstimulated saliva samples were collected before and after selected 1-h training sessions at 2 weekly intervals, over 12 weeks. Salivary IgA concentration was measured by ELISA and IgA secretion rate calculated (microg IgA x ml -1 x ml saliva x min -1). Players reported URTI symptoms and recorded training and competition in daily logs. Data analysis showed that higher incidence of URTI was significantly associated with increased training duration and load, and competition level, on a weekly basis. Salivary IgA secretion rate (S-IgA) dropped significantly after 1 hour of tennis play. Over the 12-week period, pre-exercise salivary IgA concentration and secretion rate were directly associated with the amount of training undertaken during the previous day and week (p < 0.05). However, the decline in S-IgA after 1 h of intense tennis play was also positively related to the duration and load of training undertaken during the previous day and week (p < 0.05). Although exercise-induced suppression of salivary IgA may be a risk factor, it could not accurately predict the occurrence of URTI in this cohort of athletes.

Adaptation, Physiological↗
PubMed2000

Acute exercise effects on the immune system.

PURPOSE: In recent years, health professionals have placed increased attention on the benefits of physical activity for maintaining health in the general population as well as regaining health in many disease states. Conversely, reports of apparent decreases in immune cell function after acute exercise are widespread in the literature. The purpose of this article is to evaluate critically the available data and currently employed methods, with the aim of establishing whether genuine or artefactual alterations of immune function are being reported. During and immediately after exercise, the total number of white blood cells in peripheral blood samples increases, such that the relative proportions of cell types within the leukocyte pool are altered. A number of important areas of discussion arise from these shifts in the number of circulating cells after exercise, not least of which is the artefactual effects they may have on currently employed assays of immune cell function. Recent advances in methodology are beginning to call into question the assumption that acute exercise has any genuine immunosuppressive effect. CONCLUSION: At present, there is little evidence to suggest that the range of acute exercise intensities and durations recommended by ACSM has a major detrimental effect on the function of individual T- and B-lymphocytes, natural killer cells and neutrophils. Although individual cells may not be as adversely affected as previously supposed, it is unclear whether the numerical content of the circulating population is an important clinical consideration.

Exercise↗
PubMed1998

The case history of an elite ultra-endurance cyclist who developed chronic fatigue syndrome.

An elite ultra-endurance athlete, who had previously undergone physiological and performance testing, developed chronic fatigue syndrome (CFS). An incremental cycling exercise test conducted while he was suffering from CFS indicated decreases in maximum workload achieved (Wmax; -11.3%), the maximum oxygen uptake (VO2max; -12.5%), and the anaerobic threshold (AT; -14.3%) compared to pre-CFS data. A third test conducted after the athlete had shown indications of significant improvement in his clinical condition revealed further decreases in Wmax (-7.9%), VO2max (-10.2%) and AT (-8.3%). These data, along with submaximal exercise data and muscle biopsy electron microscopic analyses, suggest that the performance decrements were the result of detraining, rather than an impairment of aerobic metabolism due to CFS per se. These data may be indicative of central, possibly neurological, factors influencing fatigue perception in CFS sufferers.

Adult↗
PubMed1998

A simple bacterial bioassay for the measurement of L-glutamine.

The amino acid L-glutamine has been shown to be important to numerous cells in the body. However, the routine measurement of glutamine in biological solutions is complicated by its relative instability, particularly at extremes of pH. We report a simple bacterial bioassay method for the estimation of glutamine, carried out at neutral pH, using an Escherichia coli that is specifically dependent on the presence of glutamine for replication. The assay is simple to perform and we have shown it to be highly reproducible. Furthermore, we observed significant correlation between the estimations of glutamine by the bioassay system and current methodologies. The levels of glutamine recorded were higher than by other methods. We also found that deproteinization and neutralization of samples allowed them to be stored at -70 degrees C for up to 24 weeks without deterioration.

Biological Assay↗
PubMed1997

Acute intensive interval training and in vitro t-lymphocyte function.

Five male endurance-trained runners completed an interval running session of 15 x 1-min intervals at 95% VO2 max. Venous blood samples were collected pre-exercise and then immediately, 30- and 60-minutes post-exercise. The response of cultures of total lymphocytes to mitogen (phytohaemagglutinin) were significantly reduced immediately after exercise, but returned to resting levels by 30-min of recovery. Conversely, the mitogen response of cultures of pure T-lymphocytes (CD4+ and CD8+ cells), separated using a magnetic separation technique, showed no significant change during the exercise and recovery periods. These data showed directly that there was no apparent change in the functional capability of T-lymphocytes following an intensive interval training session. Furthermore, there were significant changes in the composition of the total lymphocyte cultures immediately post-exercise; increased numbers of natural killer (NK) cells (CD56+) and T-suppressor cells (CD8+) and decreased numbers of T-helper cells (CD4+). There were also significant correlations between total mitogen response and the composition of the cultured lymphocytes. These data indicated that the large increases in NK cells, relative to T-cells, following intensive exercise, were the most likely cause of the reduced mitogen response of total lymphocyte cultures.

Adult↗
PubMed1997

Training adaptation and biological changes among well-trained male triathletes.

The distinction between training and overtraining responses is an important prerequisite for any potential marker for monitoring overtraining in athletes. In this study, eight well-trained male triathletes undertook physical performance assessments, at 6 weekly intervals, throughout a 9-month intensive training season. At each assessment, a resting blood sample was obtained for determination of a number of biological parameters previously associated with overtraining. All athletes produced significant (P < 0.05) improvements in running speed at anaerobic threshold (ATRS) from 15.6 +/- 0.2 k.h-1 at the start of the season to 16.6 +/- 0.6 k.h-1 at the time of major competitions. This improvement in performance was taken as evidence of well balanced training programs. Significant changes (P < 0.05) in plasma glutamine and plasma uric acid concentrations were observed during the training season, and both correlated moderately with ATRS (r = 0.365 and r = -0.328, respectively). None of the other parameters measured showed any significant changes during the training season. The elevations in plasma glutamine concentration observed in response to long-term balanced training may be distinguishable from previous reports of decreased glutamine concentrations in overtrained athletes, making it a potentially valuable tool in the monitoring of overtraining in athletes.

Adult↗
PubMed1996

The emerging role of glutamine as an indicator of exercise stress and overtraining.

Glutamine is an amino acid essential for many important homeostatic functions and for the optimal functioning of a number of tissues in the body, particularly the immune system and the gut. However, during various catabolic states, such as infection, surgery, trauma and acidosis, glutamine homeostasis is placed under stress, and glutamine reserves, particularly in the skeletal muscle, are depleted. With regard to glutamine metabolism, exercise stress may be viewed in a similar light to other catabolic stresses. Plasma glutamine responses to both prolonged and high intensity exercise are characterised by increased levels during exercise followed by significant decreases during the post-exercise recovery period, with several hours of recovery required for restoration of pre-exercise levels, depending on the intensity and duration of exercise. If recovery between exercise bouts is inadequate, the acute effects of exercise on plasma glutamine level may be cumulative, since overload training has been shown to result in low plasma glutamine levels requiring prolonged recovery. Athletes suffering from the overtraining syndrome (OTS) appear to maintain low plasma glutamine levels for months or years. All these observations have important implications for organ functions in these athletes, particularly with regard to the gut and the cells of the immune system, which may be adversely affected. In conclusion, if methodological issues are carefully considered, plasma glutamine level may be useful as an indicator of an overtrained state.

Animals↗
PubMed1995

The haematological, biochemical and immunological profile of athletes suffering from the overtraining syndrome.

To help clarify the overtraining syndrome (OTS), a combination of parameters were measured in ten athletes who were suffering from OTS. Blood samples were obtained at rest and a range of haematological, biochemical and immunological tests were carried out on the samples. For each parameter, the mean value for the group was compared to an established normal range amongst age-matched controls. The subjects were also asked to complete a questionnaire to establish the severity of their condition. The data indicated that the debilitating fatigue experienced by the OTS sufferers was not related to any of the blood parameters traditionally associated with chronic exercise stress, since levels were normal in OTS. The only parameter measured which deviated significantly from the normal range for both the sedentary controls and the athletes was the plasma concentration of glutamine. Although the data in this study would suggest that plasma glutamine concentrations represented an objective, measurable difference between OTS subjects and normal controls, it remains to be shown that there is any correlation between glutamine concentrations and other clinical symptoms of OTS such as physical capability.

Adult↗
PubMed1995

Serum free cortisol responses to a standard exercise test among elite triathletes.

Eighteen elite male triathletes completed an incremental treadmill run to volitional exhaustion, followed by two maximal cycle ergometer sprints. Venous blood samples were obtained at rest (R), immediately post- (P) and one hour postexercise (H). Serum was analysed for total cortisol (TC) by a radioimmunoassay, and free cortisol (FC) by a temperature and time dependent ultrafiltration/dialysis method. Mean (+SE) resting cortisol levels were 627 + or - 23 (TC) and 12.5 + or - 2.5 nmol 1(-1)(FC). The mean percentage increase in TC (P vs. R) was 49.0 + 73%, accompanied by a 344 + or - 47% increase in FC. Significantly divergent (p<0.001) total cortisol responses (H vs. P) were observed within the group, and the athletes were divided into two subgroups (A and B) on this basis. In group A, both TC and FC returned to resting levels. In group B, there was a further slight increase in TC, accompanied by a significant (p<0.01) increase in FC reaching 851 + or - 268% of resting levels. These data suggest that exercise-induced increases in free cortisol, and hence its catabolic effect, are of much greater relative magnitude than TC changes. The relationship between TC and FC was best fitted to an exponential regression, with a clearcut change in slope at 700 nmol 1(-1)(TC) suggesting saturation of the binding protein. We suggest that the measurement of cortisol in athletes be reassessed, favouring determination of FC in the future.

Adult↗