Inter-unit variability in two ParvoMedics TrueOne 2400 automated metabolic gas analysis systems.

Knowing the inter-unit variability, especially the technological error, is important when using many physiological measurement systems, yet no such inter-unit analysis has been undertaken on duplicate automated gas analysis systems. This study investigated the inter-unit performance of two identical ParvoMedics TrueOne 2400 automated gas analysis systems during a range of submaximal steady-state exercises performed on an electromagnetic cycle ergometer. Fifteen adult males were tested on two separate days a rest, 30, 60, 90, and 120 Watts with the duplicate gas analysis units arranged (1) collaterally (2 min of steady-state expired gas was alternately passed through each system), and (2) simultaneously (identical steady-state expired gas was passed simultaneously through both systems). Total within-subject variation (biological + technological) was determined from the collateral tests, but the unique inter-unit variability (technological error between identical systems) was shown by the simultaneous tests. Absolute percentage errors (APE), coefficient of variations (CV), effect sizes and Bland-Altman analyses were undertaken on the metabolic data, including expired ventilation (V (E)), oxygen consumption (VO(2)) and carbon dioxide production (VCO(2)). The few statistically significant differences detected between the two duplicate systems were determined to have small or trivial effect sizes, and their magnitudes to be of little physiological importance. The total within-subject variations for VO(2), VCO(2) and V (E) each equated to a mean CV and mean APE value of ~4 and ~6 %, whilst the respective inter-unit technological errors equated to ~1.5 and ~2.1 %. The two ParvoMedics TrueOne 2400 systems demonstrated excellent inter-unit agreement.

Validity, reliability and stability of the portable Cortex Metamax 3B gas analysis system.

This study investigated the performance of the portable Cortex Metamax 3B (MM3B) automated gas analysis system during both simulated and human exercise using adolescents. Repeated measures using a Gas Exchange System Validator (GESV) across a range of simulated metabolic rates, showed the MM3B to be adequately reliable (both percentage errors, and percentage technical error of measurements <2%) for measuring expired ventilation (V (E)), oxygen consumption (VO(2)), and carbon dioxide production (VCO(2)). Over a 3 h period, the MM3B was shown to be acceptably stable in measuring gas fractions, as well as V (E), VO(2), and VCO(2) generated by the GESV, especially at moderate and high metabolic rates (drifts <2% and of minor physiological significance). Using eight healthy adolescents during rest, moderate, and vigorous cycle ergometry, the validity of the MM3B was tested against the primary criterion Douglas bag method (DBM) and a secondary criterion machine known to be accurate, the Jaeger Oxycon Pro system. No significant errors in V (E) were noted, yet the MM3B significantly overestimated both VO(2) and VCO(2) by approximately 10-17% at moderate and vigorous exercise as compared to the DBM and at all exercise levels compared to the Oxycon Pro. No significant differences were seen in any metabolic variable between the two criterion systems (DBM and Oxycon Pro). It is concluded the MM3B produces acceptably stable and reliable results, but is not adequately valid during moderate and vigorous exercise without some further correction of VO(2) and VCO(2).

Exercise and diet in weight management: updating what works.

The world is facing major problems associated with the rapid increase in levels of overweight and obesity. Solving this problem via appropriate modifications to exercise habits and/or diet appears easy, but in practice it is inordinately difficult and only a small percentage manage to maintain their weight loss over the long term. However, a number of strategies can be used to increase the chances of success. Medical doctors, dieticians and other allied health professionals are potentially well placed to provide guidance to those at risk of overweight/obesity. This review is aimed at supporting major initiatives targeting an increase in community physical activity to help reduce the prevalence of overweight/obesity, such as the "Change4Life" campaign in the UK (http://www.nhs.uk/change4life) and the "Exercise is Medicine" campaign in the USA (http://www.exerciseismedicine.org). By providing a concise summary of the evidence-based research that can be easily understood by a wide range of health professionals, this review hopes to provide a useful document that can be used to enhance preventive counselling by promoting appropriate changes in lifestyle that will ultimately increase levels of physical activity, as well as reduce levels of overweight/obesity and other associated chronic hypokinetic conditions.

Validity and normative data for thirty-second chair stand test in elderly community-dwelling Hong Kong Chinese.

It is important to establish valid field measures of lower body strength in the elderly, and to provide representative normative values that are culturally specific in order to help health professionals in the risk assessment of this group. A sample of 1,038 elderly Hong Kong Chinese undertook a 30-sec chair stand test (30CST), with a subsample of 143 completing isometric measures of maximal hip flexion and knee extension, plus a habitual physical activity questionnaire. The 30CST was significantly, yet only weakly, correlated with the isometric strength measures (r approximately 0.3-0.4), but accurately discriminated between levels of habitual physical activity and across ages in decades. The normative values generated provide useful data for health screening in this elderly Hong Kong population, but do not compare well with their healthier US counterparts.

Improving aerobic power in primary school boys: a comparison of continuous and interval training.

The purpose of this study was to assess whether the magnitude of change in aerobic power was different in boys (mean age 10.25 +/- 0.50 y) who followed a high-intensity interval training protocol, compared to those who followed a moderate-intensity continuous training protocol. Boys were assigned to either a control group (n = 15), a continuous training group (n = 10), or an interval training group (n = 10). They completed peak oxygen uptake tests at baseline and following an 8-week training period. The control group continued with normal activity habits, whilst the continuous training group followed a 20-minute steady-state cycle protocol at 80-85 % of the maximal heart rate, and the interval training group completed 30-s sprints on a cycle ergometer, interspersed with active rest periods. The two training protocols were designed to incur similar cardiovascular work over the 20 minutes of each training session. Significant increases (p < 0.05) in peak oxygen uptake were noted for both the interval and continuous training groups. The interval training group showed marked pre- to post-increases in both peak oxygen pulse, oxygen pulse at the ventilatory threshold, and ventilatory threshold that were not apparent in the continuous group boys. It would appear that a high-intensity interval protocol confers a different training effect in comparison to continuous steady-state training in boys. Possible mechanisms that underpin these adaptations may include increased blood volume and a concomitant adjustment in stroke volume.

153Sm EDTMP for bone marrow ablation prior to stem cell transplantation for haematological malignancies.

This study examined the safety of adding 153Sm lexidronam to standard conditioning regimens in patients undergoing stem cell transplantation for marrow based haematological malignancies in whom total-body irradiation as part of conditioning was desirable but not feasible. Ten such patients were enrolled, seven with multiple myeloma. An escalating regimen of 19-45 GBq of 153Sm lexidronam was added 12-14 days prior to the standard transplantation regimen. Evaluation parameters included time to engraftment, status at day +100 by International Bone Marrow Transplant Registry (IBMTR) criteria and toxicity during this period. Absorbed marrow radiation doses were estimated using the MIRDOSE 3 program. No adverse events were attributable to 153Sm lexidronam. Of the seven patients with multiple myeloma, four achieved complete response, two partial response, and another had stable monoclonal band at 3 months post-transplant. One patient with Refractory Anaemic with Excess Blasts in transformation (RAEBt) died of a presumed fungal infection, whilst another with acute myeloid leukaemia relapsed, dying at day +153. A patient with low-grade lymphoma showed no evidence of residual disease at day +100. The total marrow absorbed dose was estimated to be 0.7+/-0.2 mGy x MBq(-1). Regional uptake was markedly non-uniform with poor uptake in the appendicular skeleton. Dose-limiting toxicity was not attained. At the activities used 153Sm lexidronam was not associated with additional toxicity in this population. Adequate absorbed radiation dose to appendicular marrow is unlikely to be deliverable by this approach alone.

Estimating uptake in liver and abdominal tumours for radionuclide therapy dosimetry.

Historically, patients for radionuclide therapy have received fixed activities, sometimes normalized to body weight or body surface area. As radionuclide therapy develops, however, practitioners are becoming interested in individualized doses. This requires individual estimates of uptake to be routinely available. Such estimates need not necessarily be highly accurate but the magnitude of associated errors must be known. This paper looks specifically at simple methods for estimating relative (tumour to organ) uptake and also absolute (organ) uptake, for abdominal tumours and the liver. For relative uptake, the ratio of geometric mean counts gives a rough estimate, to within a factor of 2. Absolute liver uptake can be estimated from the geometric mean of liver counts but a correction must be applied for patient attenuation. Such a correction can be calculated solely from the patient's height and weight. The patient weight alone gives a correlation coefficient of 0.86, when plotted against the measured attenuation. However, this correction does not work well for patients heavier than 100 kg. The attenuation index, which is calculated from a patient's weight and height, gives a correlation coefficient of 0.90, for patients ranging in weight from 41 kg to 120 kg.

Automated metabolic gas analysis systems: a review.

The use of automated metabolic gas analysis systems or metabolic measurement carts (MMC) in exercise studies is common throughout the industrialised world. They have become essential tools for diagnosing many hospital patients, especially those with cardiorespiratory disease. Moreover, the measurement of maximal oxygen uptake (VO2max) is routine for many athletes in fitness laboratories and has become a defacto standard in spite of its limitations. The development of metabolic carts has also facilitated the noninvasive determination of the lactate threshold and cardiac output, respiratory gas exchange kinetics, as well as studies of outdoor activities via small portable systems that often use telemetry. Although the fundamental principles behind the measurement of oxygen uptake (VO2) and carbon dioxide production (VCO2) have not changed, the techniques used have, and indeed, some have almost turned through a full circle. Early scientists often employed a manual Douglas bag method together with separate chemical analyses, but the need for faster and more efficient techniques fuelled the development of semi- and full-automated systems by private and commercial institutions. Yet, recently some scientists are returning back to the traditional Douglas bag or Tissot-spirometer methods, or are using less complex automated systems to not only save capital costs, but also to have greater control over the measurement process. Over the last 40 years, a considerable number of automated systems have been developed, with over a dozen commercial manufacturers producing in excess of 20 different automated systems. The validity and reliability of all these different systems is not well known, with relatively few independent studies having been published in this area. For comparative studies to be possible and to facilitate greater consistency of measurements in test-retest or longitudinal studies of individuals, further knowledge about the performance characteristics of these systems is needed. Such information, along with the costs and the common features associated with these systems, may aid physicians and scientists to select a system that is best suited to their requirements and may also improve the quality of these frequently-reported physiological measures.

Passive smoking and respiratory symptoms in primary school children in Hong Kong. Child Health and Activity Research Group (CHARG).

1. We aimed to study whether passive smoking is associated with respiratory ill health in primary school children in Hong Kong. 2. In this cross-sectional study, a standardised structured questionnaire was used to obtain information on respiratory symptoms, smokers in the household and smoking habit of the children. A random sample of 30 primary schools was included. Four classes were randomly selected for each school, one class each from each school year of primary 3-6. A total of 3964 children aged 8 - 13 years completed the questionnaire during October 1995-May 1996. The response rate was over 94%. 3. In 3480 children who had never smoked, after adjusting for gender, age, place of birth and living district, the odds ratios (95% confidence interval) were: (a) throat problems, 1.35 (1.08-1.68); (b) cough, 1.54 (1.28-1.84); (c) phlegm, 1.43 (1.21-1.70); (d) wheezing, 1.21 (0.89-1.41); (e) nose problems, 1.17 (1.02-1.35). The odds ratios increased with increasing number of smokers at home (P for trend < 0.001; except for wheezing, P=0.3). The odds ratios for having any of the above symptoms for one, two and three smokers at home were respectively 1.15 (0.99-1.34), 1.48 (1.16-1.88) and 2.03 (1.47 - 2.81); P for trend < 0.001. 4. We conclude that the results provide further evidence that passive smoking is a cause of respiratory ill health in school children in Hong Kong.

Prospective evaluation of 2-[18F]-2-deoxy-D-glucose positron emission tomography in staging of regional lymph nodes in patients with cutaneous malignant melanoma.

PURPOSE: To assess prospectively the accuracy of 2-[l8F]-2-deoxy-D-glucose positron emission tomography (FDG-PET) for predicting regional node involvement in cutaneous malignant melanoma (CMM). PATIENTS AND METHODS: Twenty-three patients with CMM (primary lesions > 1.5 mm thick) scheduled for lymph node dissection (LND) were preoperatively studied with FDG-PET. Thirteen patients underwent therapeutic LND of 14 node basins, while nine patients had elective LND of 10 node basins. Medical problems precluded surgery in one patient. Two observers unaware of the clinical node status-apart from whether a recent surgical scar was present-read attenuation-corrected reconstructed transverse images acquired between 50 and 60 minutes after injection. Intensity of FDG uptake was scored as 0 to 3 + on a semiquantitative four-point scale: 0, no uptake; 1 +, faint; 2 +, moderate; and 3 +, intense uptake. A node group was considered positive on FDG-PET if it contained at least one focus of FDG uptake of > or = 2+ intensity. Histopathologic examination of the 24 dissected node groups served as a reference. RESULTS: Considering regional node basins, PET imaging demonstrated 11 true-positive (TP), 10 true-negative (TN), two false-negative (FN), and one false-positive (FP) result, for an overall accuracy of 88%. Histopathologic from one FN case showed seven malignant cells in a marginal node sinus. The FP was due to reactive changes postbiopsy. In one patient, clinically involved lymph nodes were correctly categorized TN by PET. At least four additional 2 + foci seen outside the dissected regions on PET may represent metastases and are being monitored. CONCLUSION: FDG-PET accurately predicted regional node status in 88% of CMM cases. The failure to detect micrometastatic disease may be due to the limitations of the imaging equipment and technique used here.

Back injuries in competitive squash players.

BACKGROUND: The aim of this investigation was to examine the prevalence of back injuries in competitive squash players. EXPERIMENTAL DESIGN: a retrospective analysis was made using a cross-section of current competitive squash players (survivor population). SETTING/PARTICIPANTS: an attempt was made to distribute a questionnaire on back injuries to all competitive squash players registered in the Otago provincial area, New Zealand, (n = 1047), of which 495 questionnaires were returned (47.3% compliance). INTERVENTIONS: variables were cross-tabulated and analysed via descriptive statistics, paired t-tests, chi-analyses of trend and chi 2 tests of significance. MEASURES: the questionnaire obtained information on demographics, the level of play (ability), overall volume of play (average frequency and duration of all exposures), plus the occurrence and severity of back injury. RESULTS: Nearly 52% of the sample reported they had suffered back injury. Of these, 33.5% claimed squash initiated their injury, 20.6% claimed squash exacerbated a previous back injury and the remaining 45.9% felt that squash had no detrimental effect on their back injury. Significantly higher frequencies of back injury were observed in males (56.5% compared to 46.4% in females, p = 0.033), in players of higher grade (p = 0.006),and with increased frequency (p = 0.01), but not duration of play (p = 1.0). CONCLUSIONS: These results suggest that the greater activity and possible over-reaching for the ball associated with higher levels of play may increase the risk of back injury and provides tentative support for the notion that back injuries in squash players might be related to periods of relative over-use.

Exercise and health---new imperatives for public health policy in Hong Kong.

Physical inactivity is an important and largely avoidable cause of incapacity. Regular physical activity protects against several chronic diseases, including cardiovascular disease---one of the major causes of death in Hong Kong. Significant benefits can be achieved by regular participation in moderate amounts of either recreational or general lifestyle physical activities. Even more is gained from increasing the frequency, duration, and vigour of exercise. In Hong Kong, 59% of all adults lead a fairly sedentary lifestyle and only one in three exercise at levels that are thought to offer significant health benefits. An even more disturbing fact is that Hong Kong probably has the most inactive primary level schoolchildren in the world. The prevalence of these risk behaviours should make schoolchildren a priority for any public health prevention programme.

Instrumentation of an ergometer to monitor the reliability of rowing performance.

The aim of this study was to develop a portable data-acquisition system to measure the stroke-by-stroke power output and the force developed at the feet during simulated rowing, and to use the system to investigate the reliability of selected variables used to describe rowing performance. Using a Concept II rowing ergometer, the instantaneous power output was calculated as the product of the force at the handle, measured using a small transducer mounted near the handle, and the velocity of the handle, measured using an infra-red emitter-receiver to detect the passage of each vane of the flywheel. The cumulative force at the feet was measured using two force-plates, one mounted under each foot. The outputs from all transducers were sampled at 30 Hz using an 80386SX computer running Asyst data-acquisition software. Excellent linearity in all transducers was established and a calibration of the system revealed measurement errors of less than 3%. The reliability of the variables used to describe rowing performance was studied using a repeated 90 s maximal test on seven experienced oarsmen. Statistical analysis indicated that, of the 14 variables used, only two failed to meet the set criterion. In conclusion, it was found that a rower's performance during simulated rowing was very reliable and that the selected variables used in this study could be used to objectively describe performance on a rowing ergometer.

Effects of artificially-induced anaemia on sudomotor and cutaneous blood flow responses to heat stress.

The influence of artificially induced anaemia on thermal strain was evaluated in trained males. Heat stress trials (38.6 degrees C, water vapour pressure 2.74 kPa) performed at the same absolute work rates [20 min of seated rest, 20 min of cycling at 30% peak aerobic power (VO2pcak), and 20 min cycling at 45% VO2peak] were completed before (HST1) and 3-5 days after 3 units of whole blood were withdrawn (HST2). Mild anaemia did not elevate thermal strain between trials, with auditory canal temperatures terminating at 38.5 degrees C [(0.16), HST1] and 38.6 degrees C [(0.13), HST2; P > 0.05]. Given that blood withdrawal reduced aerobic power by 16%, this observation deviates from the close association often observed between core temperature and relative exercise intensity. During HST2, the absolute and integrated forearm sweat rate (mSW) exceeded control levels during exercise (P < 0.05), while a suppression of forehead mSW occurred (P < 0.05). These observations are consistent with a possible peripheral redistribution of sweat secretion. It was concluded that this level of artificially induced anaemia did not impact upon heat strain during a 60-min heat stress test.

An evaluation of the role of skin temperature during heat adaptation.

This project sought to evaluate the importance of skin temperature during heat acclimation, using an isothermal-strain model. Two groups of seven matched males, participated (1 h per day, 10 days) in one of two conditions: (i) temperate physical training (TEMP: 22.4 +/- 0.7 degrees C, relative humidity (r.h.) 41.0 +/- 0.9%); or (ii) combined physical training and heat acclimation (HEAT: 38.2 +/- 0.7 degrees C, r.h. 39.7 +/- 1.3%). Isothermal strain was induced in both groups by rapidly elevating rectal temperature by 1 degree C (cycling), then holding it constant by manipulating external work. Subjects completed two three-phase heat stress tests (39.8 +/- 0.1 degrees C, r.h. 38.6 +/- 1.2), consisting of 20 min rest, then 20 min cycling at each of 30% and 45% of peak power, before and after each regimen. While there was a difference of 4.2 degrees C in mean skin temperature between treatments, both regimens elicited a similar peripheral sudomotor increase, indicating a core temperature dependent adaptation. However, based on significant pre- vs. post-acclimation decreases in average auditory canal temperature (0.4 +/- 0.1 degree C), average forehead skin blood flow (26%), average perceived exertion (11%), and a 5% increase in average forehead sweat rate (0.1 +/- 0.04 mg cm-2 min-1), the HEAT regimen elicited a more complete acclimation. While elevation in core temperature is critical to acclimation, it also appears necessary to expose subjects to an external thermal stress. This observation has not been previously demonstrated under conditions of isothermal strain, and verifies the importance of skin temperature elevation in the acclimation process.