Dynamics of the heart rate variability and oxygen saturation response to acute normobaric hypoxia within the first 10 min of exposure

Although the heart rate variability (HRV) response to hypoxia has been studied, little is known about the dynamics of HRV after hypoxia exposure. The purpose of this study was to assess the HRV and oxygen saturation (SpO₂) responses to normobaric hypoxia (FiO₂ = 9·6%) comparing 1 min segments to baseline (normoxia). Electrocardiogram and SpO₂ were recorded during a 10‐min hypoxia exposure in 29 healthy male subjects aged 26·0 ± 4·9 years. Baseline HRV values were obtained from a 5‐min recording period prior to hypoxia. The hypoxia period was split into 10 non‐overlapping 1‐min segments and time domain HRV indexes (RMSSD and SDNN) were calculated for each segment. Differences (Δ) from baseline values were calculated and transformed using natural logarithm (Ln). This study revealed that the decrease in ΔSpO₂ became significant (P<0·001) in the first minute of hypoxia, the decrease in ΔLn RMSSD became significant (P = 0·002) in the second minute, and the decrease in ΔLn SDNN became significant (P = 0·001) in the third minute. Between the second and fifth minute of hypoxia, ΔSpO₂ correlated with ΔLn RMSSD (r = 0·57, P<0·001) and ΔLn SDNN (r = 0·44, P<0·001). Five min after the onset of hypoxia, ΔSpO₂ was significantly (P = 0·002) decreased but changes in ΔLn RMSSD (P = 0·344) and ΔLn SDNN (P = 0·558) were not significant. In conclusion, the decrease in HRV was proportional to desaturation but only during the first 5 min of hypoxia.     

Influence of exercise intensity on systemic oxidative stress and antioxidant capacity

The aim of the current study was to examine the influence of exercise intensity on systemic oxidative stress (OS) and endogenous antioxidant capacity. Non‐smoking, sedentary healthy adult males (n = 14) participated in two exercise sessions using an electronically braked cycle ergometer. The first session consisted of a graded exercise test to determine maximal power output and oxygen consumption (VO_2max). One week later, participants undertook 5‐min cycling bouts at 40%, 55%, 70%, 85% and 100% of VO_2max, with passive 12‐min rest between stages. Measures of systemic OS reactive oxygen metabolites (dROM), biological antioxidant potential (BAP), heart rate (HR), VO₂, blood lactate and rating of perceived exertion were assessed at rest and immediately following each exercise stage. Significant (P<0·05) differences between exercise bouts were examined via repeated measures ANOVA and post hoc pairwise comparisons with Bonferroni correction. Increasing exercise intensity significantly augmented HR (P<0·001), VO₂ (P<0·001), blood lactate (P<0·001) and perceived exertion (P<0·001) with no significant effect on dROM levels compared with resting values. In contrast, increasing exercise intensity resulted in significantly (P<0·01) greater BAP at 70% (2427 ± 106), 85% (2625 ± 121) and 100% (2651 ± 92) of VO_2max compared with resting levels (2105 ± 57 μmol Fe²⁺/L). The current results indicate that brief, moderate‐to‐high‐intensity exercise significantly elevates endogenous antioxidant defences, possibly to counteract increased levels of exercise‐induced reactive oxygen species. Regular moderate‐to‐high‐intensity exercise may protect against chronic OS associated diseases via activation, and subsequent upregulation of the endogenous antioxidant defence system.     

Changes in transfer factor of the lung in response to bronchodilatation

Measurement of the transfer factor for carbon monoxide (T_LCO) is a widely used clinical lung function test. Although it is frequently applied in patients with bronchial obstruction, there is little information on the effects of bronchodilatation on the test. We therefore measured T_LCO in 40 patients before and after inhalation of terbutaline. T_LCO was measured with the single‐breath technique in 20 patients and with the intra‐breath technique in 20 patients. T_LCO was also measured in 20 healthy subjects with the single‐breath technique. Forced expiratory volume (FEV₁) increased from 2·9 ± 1·1 to 3·2 ± 1·2 l in patients with bronchial obstruction in response to terbutaline inhalation. T_LCO increased from 8·2 ± 2·6 to 8·6 ± 2·7 mmol min^–1 kPa^–1 (P< 0·001) and alveolar volume (V_A) from 5·74 ± 1·21 to 5·90 ± 1·21 l (P<0·001). There was no difference between the single‐breath and the intra‐breath techniques. There was little change in FEV₁ in the healthy subjects in response to terbutaline. T_LCO increased from 10·2 ± 2·1 to 10·5 ± 2·2 mmol min^–1 kPa^–1 (P< 0·01), but there was no change in V_A. The increase in T_LCO in patients may partly be explained by improved distribution of the inhaled gas. In healthy subjects, terbutaline may increase pulmonary capillary volume. We conclude that bronchodilatation results in a small increase in T_LCO in patients with light to moderate bronchoconstriction as well as in healthy subjects. The effect is small and should in most cases be simple to account for in the interpretation of pulmonary function tests, provided the patient’s treatment is known.     

A comparison of dynamic contrast‐enhanced CT and MR imaging‐derived measurements in patients with cervical cancer

This work is to compare the kinetic parameters derived from the DCE‐CT and ‐MR data of a group of 37 patients with cervical cancer. The modified Tofts model and the reference tissue method were applied to estimate kinetic parameters. In the MR kinetic analyses using the modified Tofts model for each patient data set, both the arterial input function (AIF) measured from DCE‐MR images and a population‐averaged AIF from the literature were applied to the analyses, while the measured AIF was used for the CT kinetic analysis. The kinetic parameters obtained from both modalities were compared. Significant moderate correlations were found in modified Tofts parameters [volume transfer constant(K^trans) and rate constant (k_ep)] between CT and MR analysis for MR with the measured AIFs (R = 0·45, P<0·01 and R = 0·40, P<0·01 in high‐K^trans region; R = 0·38, P<0·01 and R = 0·80, P<0·01 in low‐K^trans region) as well as with the population‐averaged AIF (R = 0·59, P<0·01 and R = 0·62, P<0·01 in high‐K^trans region; R = 0·50, P<0·01 and R = 0·63, P<0·01 in low‐K^trans region), respectively. In addition, from the Bland–Altman plot analysis, it was found that the systematic biases (the mean difference) between the modalities were drastically reduced in magnitude by adopting the population‐averaged AIF for the MR analysis instead of the measured ones (from 51·5% to 18·9% for K^trans and from 21·7% to 4·1% for k_ep in high‐K^trans region; from 73·0% to 29·4% for K^trans and from 63·4% to 24·5% for k_ep in low‐K^trans region). The preliminary results showed the feasibility in the interchangeable use of the two imaging modalities in assessing cervical cancers.     

Left ventricular diastolic function is enhanced after peak exercise in endurance‐trained adolescents as well as in their non‐trained controls

The aims of the study were to explore the temporal change of cardiac function after peak exercise in adolescents, and to investigate how these functional changes relate to maximal oxygen uptake (VO_2max). The cohort consisted of 27 endurance‐trained adolescents aged 13–19 years, and 27 controls individually matched by age and gender. Standard echocardiography and colour tissue Doppler were performed at rest, and immediately after as well as 15 min after a maximal cardio pulmonary exercise test (CPET) on a treadmill. The changes in systolic and diastolic parameters after exercise compared to baseline were similar in both groups. The septal E/e′‐ratio increased immediately after exercise in both the active and the control groups (from 9·2 to 11·0; P<0·001, and from 8·7 to 10·2; P = 0·008, respectively). In a comparison between the two groups after CPET, the septal E/e′‐ratio was higher in the active group both immediately after exercise and 15 min later compared to the control group (P = 0·007 and P = 0·006, respectively). We demonstrated a positive correlation between VO_2max and cardiac function including LVEF and E/e′ immediately after CPET, but the strongest correlation was found between VO_2max and LVEDV (r = 0·67, P<0·001) as well as septal E/e′ (r = 0·34, P = 0·013). Enhanced diastolic function was found in both groups, but this was more pronounced in active adolescents. The cardiac functional response to exercise, in terms of LVEF and E/e′, correlates with the increase in VO₂ uptake. These findings in trained as well as un‐trained teenagers have practical implications when assessing cardiac function.     

Acute resistance exercise with blood flow restriction effects on heart rate,double product,oxygen saturation and perceived exertion

The aim of this study was to compare the acute effect of resistance exercise (RE) with and without blood flow restriction (BFR) on heart rate (HR), double product (DP), oxygen saturation (SpO₂) and rating of perceived exertion (RPE). Twenty‐four men (21·79 ± 3·21 years) performed three experimental protocols in a random order (crossover): (i) high‐intensity RE at 80% of 1RM (HI), (ii) low‐intensity RE at 20% of 1RM (LI) and (iii) low‐intensity RE at 20% of 1RM combined with partial blood flow restriction (LI+BFR). HR, blood pressure, SpO₂ and RPE were assessed. The data were analysed using repeated measures analysis of variance and the Wilcoxon test for RPE. The results indicated that all protocols significantly increased HR, both immediately postexercise and during the subsequent 60 min (P<0·05), and postexercise DP (P<0·05), but there were no differences between protocols. The protocols of LI and LI+BFR reduced postexercise SpO₂ (P = 0·033, P = 0·007), and the LI+BFR protocol presented a perception of greater exertion in the lower limbs compared with HI (P = 0·022). We conclude that RE performed at low intensity combined with BFR seems to reduce the SpO₂ after exercise and increase HR and DP while maintaining a perception of greater exertion on the lower limbs.     

A comparison of head motion and prefrontal haemodynamics during upright and recumbent cycling exercise

The aim of this observational study was to compare head motion and prefrontal haemodynamics during exercise using three commercial cycling ergometers. Participants (n = 12) completed an incremental exercise test to exhaustion during upright, recumbent and semi‐recumbent cycling. Head motion (using accelerometry), physiological data (oxygen uptake, end‐tidal carbon dioxide [P_ETCO₂] and heart rate) and changes in prefrontal haemodynamics (oxygenation, deoxygenation and blood volume using near infrared spectroscopy [NIRS]) were recorded. Despite no difference in oxygen uptake and heart rate, head motion was higher and P_ETCO₂ was lower during upright cycling at maximal exercise (P<0·05). Analyses of covariance (covariates: head motion P>0·05; P_ETCO₂, P<0·01) revealed that prefrontal oxygenation was higher during semi‐recumbent than recumbent cycling and deoxygenation and blood volume were higher during upright than recumbent and semi‐recumbent cycling (respectively; P<0·05). This work highlights the robustness of the utility of NIRS to head motion and describes the potential postural effects upon the prefrontal haemodynamic response during upright and recumbent cycling exercise.     

Patients with Parkinson disease present high ambulatory blood pressure variability

Patients with Parkinson disease (PD) present blunted nocturnal blood pressure fall and similar ambulatory blood pressure variability (ABPV) measured by standard deviation (SD) and coefficient of variation (CV) compared with healthy subjects. However, these classical indices of ABPV have limited validity in individuals with circadian blood pressure alterations. New indices, such as the average of daytime and night‐time standard deviation weighted by the duration of the daytime and night‐time intervals (SD_dn) and the average real variability (ARV), remove the influence of the daytime and the night‐time periods on ABPV. This study assessed ABPV by SD_dn and ARV in PD. Twenty‐one patients with PD (11 men, 66 ± 2 years, stages 2–3 of modified Hoehn & Yahr) and 21 matched controls without Parkinson disease (9 men, 64 ± 1 years old) underwent blood pressure monitoring for 24 h. ABPV was analysed by 24 h, daytime and night‐time SD and CV, and by the SD_dn and ARV. Systolic/diastolic 24‐h and night‐time SD and CV were similar between the patients with PD and the controls. The patients with PD presented higher daytime systolic/diastolic CV and SD than the controls (10·4 ± 0·9/12·3 ± 0·8 versus 7·0 ± 0·3/9·9 ± 0·5%, P<0·05; 12·6 ± 1·0/9·1 ± 0·5 versus 8·6 ± 0·4/7·5 ± 0·3 mmHg, P<0·05, respectively) as well as higher systolic/diastolic SD_dn (10·9 ± 0·8/8·2 ± 0·5 versus 8·2 ± 0·3/7·1 ± 0·2 mmHg, P<0·05, respectively) and ARV (8·8 ± 0·6/6·9 ± 0·3 versus 7·2 ± 0·2/6·0 ± 0·2 mmHg, P<0·05, respectively). In conclusion, patients with PD have higher ABPV than control subjects as assessed by SD_d, CV_d, SD_dn and AVR.     

Differential effects of age on large artery stiffness and minimal vascular resistance in normotensive and mildly hypertensive individuals

Large artery stiffness and small artery structural changes are both cardiovascular risk factors. Arterial stiffness increases with age and blood pressure (BP), but it is unclear in which way large artery pulse wave velocity (PWV) and peripheral vascular resistance are related and whether age has any influence. In a cross‐sectional study, PWV and forearm minimum vascular resistance (R_min) was compared with emphasis on the impact of age. Normotensive (n = 53) and untreated hypertensive (n = 23) subjects were included based on 24‐h BP measurements. Age ranged from 21 to 79 years with an even distribution from each age decade. PWV was assessed using tonometry. Forearm R_min was measured by venous occlusion plethysmography at maximal vasodilatation induced by 10 min of ischaemia in combination with skin heating and hand grip exercise. In both normotensive and hypertensive subjects, PWV correlated significantly with age and BP. Based on median age, both groups were assigned into two equally large subgroups. Normotensive older (66 ± 7 years) and younger (35 ± 10 years) persons had different carotid‐femoral PWV (7·9 ± 1·8 versus 5·7 ± 0·9 m/s, P<0·01), but similar R_min values (3·7 ± 0·9 versus 3·6 ± 1·2 mmHg/ml/min/100 ml). Hypertensive older (63 ± 6 years) and younger (40 ± 10 years) also had different PWV (8·0 ± 1·5 versus 6·7 ± 1·1 m/s, P<0·05), but the older had lower R_min (3·1 ± 0·8 versus 4·7 ± 2·2 mmHg/ml/min/100 ml, P<0·05). In a regression analysis adjusting for age, BP, gender and heart rate, no correlation was seen between PWV and R_min. The data suggest that age differentially affects PWV and R_min and that BP can increase in older persons without affecting R_min.     

Influence of skin blood flow and source‐detector distance on near‐infrared spectroscopy‐determined cerebral oxygenation in humans

Most near‐infrared spectroscopy (NIRS) apparatus fails to isolate cerebral oxygenation from an extracranial contribution although they use different source‐detector distances. Nevertheless, the effect of different source‐detector distances and change in extracranial blood flow on the NIRS signal has not been identified in humans. This study evaluated the extracranial contribution, as indicated by forehead skin blood flow (SkBF) to changes in the NIRS‐determined cerebral oxyhaemoglobin concentration (O₂Hb) by use of a custom‐made multidistance probe. Seven males (age 21 ± 1 year) were in a semi‐recumbent position, while extracranial blood flow was restricted by application of four different pressures (+20 to +80 mmHg) to the left temporal artery. The O₂Hb was measured at the forehead via a multidistance probe (source‐detector distance; 15, 22·5 and 30 mm), and SkBF was determined by laser Doppler. Heart rate and blood pressure were unaffected by application of pressure to the temporal artery, while SkBF gradually decreased (P<0·001), indicating that extracranial blood flow was manipulated without haemodynamic changes. Also, O₂Hb gradually decreased with increasing applied pressure (P<0·05), and the decrease was related to that in SkBF (r = 0·737, P<0·01) independent of the NIRS source to detector distance. These findings suggest that the NIRS‐determined cerebral oxyhaemoglobin is affected by change in extracranial blood flow independent of the source‐detector distance from 15 to 30 mm. Therefore, new algorithms need to be developed for unbiased NIRS detection of cerebral oxygenation.     

Microcirculation of skeletal muscle adapts differently to a resistive exercise intervention with and without superimposed whole‐body vibrations

Whole‐body vibration (WBV) training is commonly practiced and may enhance peripheral blood flow. Here, we investigated muscle morphology and acute microcirculatory responses before and after a 6‐week resistive exercise training intervention without (RE) or with (RVE) simultaneous whole‐body vibrations (20 Hz, 6 mm peak‐to‐peak amplitude) in 26 healthy men in a randomized, controlled parallel‐design study. Total haemoglobin (tHb) and tissue oxygenation index (TOI) were measured in gastrocnemius muscle (GM) with near‐infrared spectroscopy (NIRS). Whole‐body oxygen consumption (VO₂) was measured via spirometry, and skeletal muscle morphology was determined in soleus (SOL) muscle biopsies. Our data reveal that exercise‐induced muscle deoxygenation both before and after 6 weeks training was similar in RE and RVE (P = 0·76), although VO₂ was 20% higher in the RVE group (P<0·001). The RVE group showed a 14%‐point increase in reactive hyperaemia (P = 0·007) and a 27% increase in blood volume (P<0·01) in GM after 6 weeks of training. The number of capillaries around fibres was increased by 15% after 6 weeks training in both groups (P<0·001) with no specific effect of superimposed WBV (P = 0·61). Neither of the training regimens induced fibre hypertrophy in SOL. The present findings suggest an increased blood volume and vasodilator response in GM as an adaptation to long‐term RVE, which was not observed after RE alone. We conclude that RVE training enhances vasodilation of small arterioles and possibly capillaries. This effect might be advantageous for muscle thermoregulation and the delivery of oxygen and nutrients to exercising muscle and removal of carbon dioxide and metabolites.     

Characterization of muscle oxygenation response to vascular occlusion: implications for remote ischaemic preconditioning and physical Performance

Remote ischaemic preconditioning is a non‐invasive intervention with potential to protect a number of organs against ischaemia–reperfusion injury and possibly improve athletic performance. Little mechanistic evidence exists to support either limb choice or cuff inflation pressure that is most effective. This preliminary study aimed to establish the dose–response effect of different occlusion pressures on skeletal muscle oxygenation and blood flow in healthy males (n = 6). In a randomized controlled crossover study, cuff inflation pressures (140,160 and 180 mmHg) were used to induce limb ischaemia (× 3 cycles of 5‐min) in upper (UL) and lower (LL) limbs on three separate occasions. Muscle oxygenation and blood flow properties of UL (flexor carpi ulnaris) and LL (vastus lateralis) were assessed using near infrared spectroscopy. Higher deoxyhaemoglobin (ΔHHb) values were consistently observed in UL (versus LL; P<0·05), no difference between pressures. Occlusion at 140 mm Hg failed to elicit decreases in tissue oxyhaemoglobin (ΔHbO₂) from resting baseline (UL and LL), with significant HbO₂ decreases only observed at 180 mmHg in LL (P<0·05). Increases in ΔHbO₂ and muscle oxygenation index (Hb_diff) above baseline were observed with cuff deflation, lasting up to 15 min into recovery in LL irrespective of occlusion pressure (P<0·05). Muscle oxygenation properties are influenced by choice of limb occluded and findings show that tissue ischaemia can be induced at much lower absolute pressures than traditionally used in RIPC studies. Blood flow and muscle oxygenation may be enhanced for at least 15 min following the last occlusion.     

Ultrasound measurements of carotid intima–media thickness by two semi‐automated analysis systems

Increased carotid intima–media thickness (cIMT) is associated with an increased risk of cardiac events and stroke. Several semi‐automated edge‐detection techniques for measuring cIMT are used for research and in clinical practice. Our aim was to compare two currently available semi‐automated techniques for the measurement of cIMT. Carotid ultrasound recordings were obtained from 99 subjects (mean age 54·4 ± 8·9 years, range 33–69) without known cardiovascular diseases using a General Electric (GE) Vivid 7 ultrasound scanner, 8‐MHz transducer. The far‐wall cIMT was evaluated 1–2 cm proximal to the carotid bulb. Three diastolic images (ECG R‐wave) from the left and three images from the right common carotid arteries were analysed using GE and Artery Measurement System (AMS) semi‐automated softwares. Mean systolic and diastolic blood pressures were 120 ± 13 and 76 ± 8 mmHg, respectively. The cIMT_mean (left + right)/2 by GE and cIMT_mean (left + right)/2 AMS were highly correlated (r = 0·92, P<0·001). Higher values were measured by GE (0·72 ± 0·12 mm) compared with AMS (0·69 ± 0·12 mm), and this was significant (P<0·001). The coefficients of variation for the intra‐observer variability of cIMT_mean (left + right)/2 were 1·0% (GE) and 2·2% (AMS). cIMT_mean measured by GE's semi‐automated edge‐detection method correlated well with that measured by AMS. However, there were small but significant systematic differences between the cIMT_mean values measured by the two techniques. Thus, the use of only one type of measurement program seems favourable in follow‐up studies and when evaluating treatment effects.     

Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols

Background: Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady‐state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal‐to‐noise (SNR) and contrast‐to‐noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction. Methods: Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non‐infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed. Results: SS_SSFP had significantly better quality scores in all categories (P = 0·037, P = 0·014, P = 0·021, P = 0·03). SNR_infarct and SNR_blood were significantly better for IR_FGRE than for SS_SSFP (P = 0·048, P = 0·018). No significant difference was found in SNR_myocardium and CNR. The myocardial volume was significantly larger with SS_SSFP (170·7 versus 159·2 ml, P<0·001), but no significant difference was found in infarct volume and infarct extent. Conclusion: SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.     

Cardiac power output and its response to exercise in athletes and non‐athletes

Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow‐ and pressure‐generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non‐athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age‐ and gender‐matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end‐diastolic volume (r = 0·54; r = 0·46, P<0·05) and end‐diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non‐athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance.     

Comparison of two methacholine challenge methods using Spira-2 or Mefar dosimeter

Two bronchial challenge protocols with breath-actuated dosimeters, Spira Elektro-2 and Mefar, with similar cumulative dose steps were compared in 28 patients with mild to moderate asthma. Methacholine challenges were performed after two different protocols at the same time of day in random order 3 or 4 days apart. The provocative dose of methacholine producing a 20% fall in forced expiratory volume in 1 second (PD₂₀) was lower when determined by Spira than with the Mefar dosimeter (P<0·05). Transition equations calculated by linear regression analysis were: PD_20mefar=exp₁₀[0·897 + 0·678(logPD_20spira)] (P<0·05; r=0·62) and PD_20spira=exp₁₀[0·759 + 0·559 (log PD_20mefar)] (P<0·05; r=0·62). The slopes were calculated by regressing the percentage fall in FEV₁ on log₁₀ (dose) and transformed as slope=100/(regression coefficient + 10). The mean slope (95% CI) for Spira was 3·1 (2·6–3·7) and for Mefar 4·4 (3·6–5·1) (P<0·005). Regression equations calculated by linear regression analysis were: slope_mefar=2·126 + 0·712 slope_spira (P<0·05; r=0·51) and slope_spira=1·551 + 0·365 slope_mefar (P<0·05; r=0·51). In conclusion, PD₂₀ was smaller and the decline in FEV₁/log(dose) curve steeper using the Spira compared with the Mefar protocol. The dose–response curves should be validated and transition equations calculated when bronchial reactivity to inhaled agents is compared, even while using apparently similar well-standardized dosimeter methods.     

Acute effects of different volumes of dynamic stretching on vertical jump performance,flexibility and muscular endurance

The purpose of this study was to examine the acute effects of different volumes of a dynamic stretching routine on vertical jump (VJ) performance, flexibility and muscular endurance (ME). Twenty‐six males (age 22·2 ± 1·3 years) performed three separate randomized conditions: (i) a control (CON) condition (5‐min jog + 12 min of resting), (ii) a 5‐min jog + a dynamic stretching routine (DS1; 6·7 ± 1·3 min) and (iii) a 5‐min jog + a dynamic stretching routine with twice the volume (DS2; 12·1 ± 1·6 min). The dynamic stretching routine included 11 exercises targeting the hip and thigh musculature. VJ performance (jump height and velocity) and flexibility were measured prior to and following all conditions, while ME was measured following all conditions. The DS1 and DS2 conditions increased VJ height and velocity (P<0·01), while the CON condition did not change (P>0·05). When compared to the CON condition, the DS1 condition did not improve ME (P>0·05), whereas the DS2 condition resulted in a significant (15·6%) decrease in the number of repetitions completed (P<0·05). Flexibility increased following all conditions (P<0·01), while the DS1 condition was significantly greater (P<0·01) than the CON condition at post‐testing. These results suggest that dynamic stretching routines lasting approximately 6–12 min performed following a 5‐min jog resulted in similar increases in VJ performance and flexibility. However, longer durations of dynamic stretching routines may impair repetitive high‐intensity activities.     

Comparison of two methods of assessing total body water at sea level and increasing high altitude

Fluid retention is a recognized feature of acute mountain sickness. However, accurate assessment of hydration, including the quantification of body water, has traditionally relied on expensive and non‐portable equipment limiting its utility in the field setting. We compared the assessment of total body water (TBW) and their relationship to total body weight using two non‐invasive methods using the NICas single‐frequency bioimpedance analysis (SF‐BIA) system and the BodyStat QuadScan 4000 multifrequency BIA system (MF‐BIA). TBW measurements were performed at rest at sea level and at high altitude (HA) at 3833 m postexercise and at rest and thereafter at rest at 4450 m and 5129 m on 47 subjects. The average age was 34·5 ± 9·3 years with an age range of 21–54 years (70·2% male). There were strong correlations between TBW assessment with both methods at sea level (r = 0·90; 95% CI 0·78–0·95: P<0·0001) and at HA (r = 0·92; 0·89–0·94: P<0·0001), however, TBW readings were 0·2 l and 1·91 l lower, respectively, with the NICaS. There was a stronger correlation between TBW and body weight with the QuadScan (r = 0·91; P<0·0001) than with the NICaS (r = 0·83; P<0·0001). The overall agreement between the two TBW methods was good, but the 95% confidence intervals around these agreements were relatively wide. We conclude that there was reasonable agreement between the two methods of BIA for TBW, but this agreement was lower at HA.     

Technetium‐99m‐anti‐tumour necrosis factor alpha scintigraphy as promising predictor of response to corticotherapy in chronic active Graves' ophthalmopathy

It has been suggested that technetium‐99m (99mTc)‐anti‐tumour necrosis factor alpha (TNF‐α) scintigraphy (SCI) may be a useful diagnostic tool in Graves' ophthalmopathy (GO). This study evaluated whether orbit total radioactivity uptake on SCI could be used to predict corticosteroid therapy (CorT) responses in active‐GO patients. A longitudinal study of patients with active GO defined by Clinical Active Score (CAS) >3/7 was done. Clinical, laboratory and SCI evaluations were performed at baseline and 3 months after concluding intravenous CorT. SCI (planar and tomographic) was assessed after intravenous injection of 10 mCi of 99mTc‐anti‐TNF‐α. Orbits and cerebral hemispheres were defined as regions of interest (ROIs) to enable orbit/hemisphere ROI‐ratios of total radioactive uptake. ROI‐ratios were considered positive at >2·5. Average total radiation uptake (TRU) was also determined for each orbit (AVG_ROI). Clinical, laboratory and SCI data were compared between responders (CAS became inactive) and non‐responders to CorT (18 patients). At baseline, AVG_ROI were higher in active OG orbits (67·3 cps) than in inactive ones (33·6 cps; P<0·05). AVG_ROI (absolute values) reduced (?29·9 cps) in CorT responders and tended (P = 0·067) to differ from variations occurred in non‐responders (+6·9 cps in patients with maintained CAS positivity post‐treatment). Higher baseline ROI‐ratios (4·9 versus 3·3; P = 0·056) and its pronounced reductions following CorT (?37% versus +56% in non‐responders; P = 0·036) tended to be associated with good CorT responses in the subgroup of GO history ≥1 year. SCI showed a good association with active eye disease and may be an additional tool to identify CorT responders.