Reference Fitness Values in the Untrained Spinal Cord Injury Population

ObjectiveEstablish reference values of cardiorespiratory fitness applicable to the general, untrained spinal cord injury (SCI) population.DesignData were retroactively obtained from 12 studies (May 2004 to May 2012).SettingAn institution-affiliated applied physiology research laboratory.ParticipantsA total of 153 men and 26 women (age, 18–55y) with chronic SCI (N=179) were included. Participants were not involved in training activities for 1 or more months before testing and were able to complete a progressive resistance exercise test to determine peak oxygen consumption (Vo₂peak).InterventionsNot applicable.Main Outcome MeasurePercentile ranking (poor<20%; fair; 20%–40%; average, 40%–60%; good, 60%–80%; excellent, 80%–100%) used to establish reference values.ResultsReference cardiorespiratory fitness values based on functional classification as paraplegic or tetraplegic were established (paraplegic: median, 16.0mL·kg⁻¹·min⁻¹; range, 1.4–35.2mL·kg⁻¹·min⁻¹; tetraplegic: median, 8.8mL·kg⁻¹·min⁻¹; range, 1.5–21.5mL·kg⁻¹·min⁻¹) for untrained men and women. For the primary outcome measure (Vo₂peak), persons with paraplegia had significantly higher values than did persons with tetraplegia (P<.001). Although men had higher values than did women, these differences did not reach significance (P=.256). Regression analysis revealed that motor level of injury was associated with 22.3% of the variability in Vo₂peak (P<.001), and an additional 8.7% was associated with body mass index (P<.001). No other measure accounted for additional significant variability.ConclusionsEstablished reference fitness values will allow investigators/clinicians to stratify the relative fitness of subjects/patients from the general SCI population. Key determinants are motor level of injury and body habitus, yet most variability in aerobic capacity is not associated with standard measures of SCI status or demographic characteristics.     

Maximal Cardiorespiratory Fitness Testing in Individuals With Chronic Stroke With Cognitive Impairment: Practice Test Effects and Test-Retest Reliability

Objectives

To evaluate, for individuals with chronic stroke with cognitive impairment, (1) the effects of a practice test on peak cardiorespiratory fitness test results; (2) cardiorespiratory fitness test-retest reliability; and (3) the relationship between individual practice test effects and cognitive impairment.

Design

Cross-sectional.

Setting

Rehabilitation center.

Participants

A convenience sample of 21 persons (men [n=12] and women [n=9]; age range, 48–81y; 44.9±36.2mo poststroke) with cognitive impairments who had sufficient lower limb function to perform the test.

Interventions

Not applicable.

Main Outcome Measure

Peak oxygen consumption (Vo₂peak, ml·kg⁻¹·min⁻¹).

Results

Test-retest reliability of Vo₂peak was excellent (intraclass correlation coefficient model 2,1 [ICC_2,1]=.94; 95% confidence interval [CI], .86–.98). A paired t test showed that there was no significant difference for the group for Vo₂peak obtained from 2 symptom-limited cardiorespiratory fitness tests performed 1 week apart on a semirecumbent cycle ergometer (test 2–test 1 difference, −.32ml·kg⁻¹·min⁻¹; 95% CI, −.69 to 1.33ml·kg⁻¹·min⁻¹; P=.512). Individual test-retest differences in Vo₂peak were, however, positively related to general cognitive function as measured by the Mini-Mental State Examination (ρ=.485; P<.026).

Conclusions

Vo₂peak can be reliably measured in this group without a practice test. General cognitive function, however, may influence the effect of a practice test in that those with lower general cognitive function appear to respond differently to a practice test than those with higher cognitive function.     

Determinants of cardiorespiratory fitness at 3, 6 and 12 months poststroke

Purpose: To better delineate intervention programs, knowledge of the factors that are associated with physical fitness in stroke survivors is crucial. This study aimed to predict cardiorespiratory fitness based on standardized measures along the several dimensions of the International Classification of Functioning, Disability and Health (ICF) model at several time intervals in the first year after stroke. Methods: Forty patients were assessed at 3, 6 and 12 months poststroke. A symptom-limited graded cycle ergometer test was used to assess cardiorespiratory fitness. Outcome variables were VO₂ peak and the Oxygen Uptake Efficiency Slope (OUES). Impairments, activity limitations, participation restrictions, personal and environmental factors were assessed to determine predictive factors. Results: Explained variance at 3, 6 and 12 months poststroke was 39%, 55% and 91% for VO₂ peak and 55%, 63% and 79% for OUES. A strong association between knee muscle strength and cardiorespiratory fitness was found at each measurement time, explaining up to 72 % of the variance in fitness. At 12 months poststroke, functional mobility, body mass index (BMI) and emotional status also contributed to explain variance. Conclusions: Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months poststroke.

Implications for Rehabilitation

• Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months post-stroke.

• Cardiorespiratory endurance training should be implemented with strength-developing exercises of both lower limbs, with emphasis on the weaker paretic side.

     

Validity of submaximal exercise testing in adults with athetospastic cerebral palsy

Satonaka A, Suzuki N, Kawamura M. Validity of submaximal exercise testing in adults with athetospastic cerebral palsy.ObjectiveTo examine the validity of the multistage submaximal cycle ergometer test for adults with athetospastic cerebral palsy.DesignCross-sectional and correlative study. Oxygen uptake and heart rates were recorded while the participants underwent the maximal cycle ergometer test and the multistage submaximal cycle ergometer test. Peak oxygen consumption (Vo₂peak) was achieved by the maximal cycle test. Maximum oxygen consumption (V?o₂max) was predicted by the multistage submaximal cycle ergometer test.SettingResearch laboratory setting.ParticipantsAdults with athetospastic cerebral palsy (N=16; 10 women and 6 men; mean age ± SD, 43.7±14.5y).InterventionsNot applicable.Main Outcome MeasurePeak Vo₂ was compared with the predicted V?o₂max.ResultsMean Vo₂peak and the predicted V?o₂max ± SD were 866.9±202.9mL/min^?1 and 857.4±248.4mL/min^?1, respectively. There was not a significant difference between Vo₂peak values and the predicted V?o₂max values (r=.28). And there was a significant correlation between Vo₂peak values and the predicted V?o₂max values (r=.94, P<.001). SE of the estimate (or SE for X to Y) was 71.2mL/min^?1, equivalent to 7.4%.ConclusionsThe multistage submaximal cycle ergometer test may provide a valid V?o₂max estimate of adults with athetospastic cerebral palsy.     

Intensity of Nordic Walking in young females with different peak O2 consumption

The purpose of this cross‐sectional study was to determine the physiological reaction to the different intensity Nordic Walking exercise in young females with different aerobic capacity values. Twenty‐eight 19–24‐year‐old female university students participated in the study. Their peak O₂ consumption (VO₂ peak kg^?1) and individual ventilatory threshold (IVT) were measured using a continuous incremental protocol until volitional exhaustion on treadmill. The subjects were analysed as a whole group (n = 28) and were also divided into three groups based on the measured VO₂ peak kg^?1 (Difference between groups is 1 SD) as follows: 1. >46 ml min^?1 kg^?1 (n = 8), 2. 41–46 ml min^?1 kg^?1 (n = 12) and 3. <41 ml min^?1 kg^?1 (n = 8). The second test consisted of four times 1 km Nordic Walking with increasing speed on the 200 m indoor track, performed as a continuous study (Step 1 – slow walking, Step 2 – usual speed walking, Step 3 – faster speed walking and Step 4 – maximal speed walking). During the walking test expired gas was sampled breath‐by‐breath and heart rate (HR) was recorded continuously. Ratings of perceived exertion (RPE) were asked using the Borg RPE scale separately for every 1 km of the walking test. No significant differences emerged between groups in HR of IVT (172·4 ± 10·3–176·4 ± 4·9 beats min^?1) or maximal HR (190·1 ± 7·3–191·6 ± 7·8 beats min^?1) during the treadmill test. During maximal speed walking the speed (7·4 ± 0·4–7·5 ± 0·6 km h^?1) and O₂ consumption (30·4 ± 3·9–34·0 ± 4·5 ml min^?1 kg^?1) were relatively similar between groups (P > 0·05). However, during maximal speed walking, the O₂ consumption in the second and third groups was similar with the IVT (94·9 ± 17·5% and 99·4 ± 15·5%, respectively) but in the first group it was only 75·5 ± 8·0% from IVT. Mean HR during the maximal speed walking was in the first group 151·6 ± 12·5 beats min^?1, in the second (169·7 ± 10·3 beats min^?1) and the third (173·1 ± 15·8 beats min^?1) groups it was comparable with the calculated IVT level. The Borg RPE was very low in every group (11·9 ± 2·0–14·4 ± 2·3) and the relationship with VO₂and HR was not significant during maximal speed Nordic Walking. In summary, the present study indicated that walking is an acceptable exercise for young females independent of their initial VO₂ peak level. However, females with low initial VO₂ peak can be recommended to exercise with the subjective ‘faster speed walking’. In contrast, females with high initial VO₂ peak should exercise with maximal speed.     

Use of Salivary Osmolality to Assess Dehydration

Abstract

Objective. To investigate the ability of salivary osmolality to assess dehydration while subjects perform alternating work/rest cycles in personal protective equipment (PPE). Methods. Eight healthy men (mean ± standard deviation age: 23.5 ± 4.9 years; body fat: 17.8% ± 5.0%; maximum volume of oxygen consumption [VO_2max]: 57.2 ± 5.5 mL·kg^?1·min^?1) performed two exercise trials: one while wearing shorts and a T-shirt (EX) and one while wearing firefighting PPE (EX+PPE). Saliva samples were taken before exercise, at minutes 40, 80, and 120 of the exercise trial, and during recovery. Results. Percent body mass loss (BML) was significantly greater while the subjects were wearing PPE (2.18% ± 0.54% vs. control 0.81% ± 0.30%). Salivary osmolality increased significantly in both trials (73.4 ± 12.4 to 125.1 ± 30.3 mOsm·kg^?1 and 70.1 ± 12.5 to 83.6 ± 17.7 mOsm·kg^?1); however, the increase in the EX+PPE trial was significantly greater than the increase in the EX trial. Plasma osmolality did not change significantly in either trial, whereas urinary osmolality increased significantly in both trials. Changes in salivary osmolality were strongly correlated with percent BML (r = 0.80; p < 0.01). Conclusion. Salivary osmolality may be a sensitive indicator of moderate dehydration under carefully controlled conditions.     

Updated Reference Standards for Cardiorespiratory Fitness Measured with Cardiopulmonary Exercise Testing: Data from the Fitness Registry and the Importance of Exercise National Database (FRIEND)

ObjectiveTo provide updated reference standards for cardiorespiratory fitness (CRF) for the United States derived from cardiopulmonary exercise (CPX) testing when using a treadmill or cycle ergometer.Patients and MethodsThirty-four laboratories in the United States contributed data to the Fitness Registry and the Importance of Exercise National Database. Analysis included 22,379 tests (16,278 treadmill and 6101 cycle ergometer) conducted between January 1, 1968, through March 31, 2021, from apparently healthy adults (aged 20 to 89 years). Percentiles of peak oxygen consumption for men and women were determined for each decade from 20 through 89 years of age for treadmill and cycle exercise modes, as well as when defining maximal effort as respiratory exchange ratio (RER) greater than or equal to 1.0 or RER greater than or equal to 1.1.ResultsFor both men and women, the 50^th percentile scores for each exercise mode decreased with age and were higher in men across all age groups and higher for treadmill compared with cycle CPX. The average rate of decline per decade over a 6-decade period was 13.5%, 4.0 mLO₂·kg^-1·min^-1 for treadmill CPX and 16.4%, 4.3 mLO₂·kg^-1·min^-1 for cycle CPX. Observationally, the mean peak oxygen consumption was similar whether using an RER criterion of greater than or equal to 1.0 or greater than or equal to 1.1 across the different test modes, ages, and for both sexes. The updated reference standards for treadmill CPX were 1.5 – 4.6 mLO₂·kg^-1·min^-1 lower compared with the previous 2015 standards whereas the updated cycling standards were generally comparable to the original 2017 standards.ConclusionThese updated cardiorespiratory fitness reference standards improve the representativeness of the US population compared with the original standards.     

Decreased aerobic capacity 4 years after aortic valve replacement in male patients operated upon for chronic aortic regurgitation

Exercise testing is underutilized in patients with valve disease. We have previously found a low physical work capacity in patients with aortic regurgitation 6 months after aortic valve replacement (AVR). The aim of this study was to evaluate aerobic capacity in patients 4 years after AVR, to study how their peak oxygen uptake (peakVO₂) had changed postoperatively over a longer period of time. Twenty‐one patients (all men, 52 ± 13 years) who had previously undergone cardiopulmonary exercise testing (CPET) pre‐ and 6 months postoperatively underwent maximal exercise testing 49 ± 15 months postoperatively using an electrically braked bicycle ergometer. Breathing gases were analysed and the patients’ physical fitness levels categorized according to Åstrand’s and Wasserman’s classifications. Mean peakVO₂ was 22·8 ± 5·1 ml × kg^?1 × min^?1 at the 49‐month follow‐up, which was lower than at the 6‐month follow‐up (25·6 ± 5·8 ml × kg^?1 × min^?1, P = 0·001). All but one patient presented with a physical fitness level below average using Åstrand’s classification, while 13 patients had a low physical capacity according to Wasserman’s classification. A significant decrease in peakVO₂ was observed from six to 49 months postoperatively, and the decrease was larger than expected from the increased age of the patients. CPET could be helpful in timing aortic valve surgery and for the evaluation of need of physical activity as part of a rehabilitation programme.     

Evaluation of three measures of cardiorespiratory fitness in independently ambulant stroke survivors

Measuring cardiorespiratory fitness (CRF) in the stroke population is challenging. Currently, the recommended method is a graded exercise test (GXT) on an ergometer such as a treadmill or cycle, which may not always be possible. We investigated whether walking tests such as the six-minute walk test (6MWT) and the shuttle walk test (SWT) may be appropriate indicators of CRF in the stroke population. Twenty-three independently ambulant stroke survivors (11 men, age 61.5 ± 18.4 years) within one-year post stroke performed the 6MWT, SWT, and cycle GXT, during which peak oxygen consumption (VO_2peak) and heart rate (HR_peak) were recorded. There were no differences (p > 0.05) in mean VO_2peak among the three tests (min-max: 17.08–18.09 mL kg^?1 min^?1). For individuals, small discrepancies in VO_2peak between the 6MWT and other tests were greater with higher fitness levels. HR_peak was significantly (p = 0.005) lower during the 6MWT. Correlations between VO_2peak and performance measures within each test were high (6MWT VO_2peak and distance: r = 0.78, SWT VO_2peak and shuttles: r = 0.73, cycle GXT VO_2peak and workload: r = 0.77) suggesting the performance measures may be clinically useful as proxy measures of CRF. Common comorbidities, such as lower-limb joint pain and poor balance, and participant’s fastest walking speed, should inform the choice of CRF test.     

Determinants of cardiorespiratory fitness at 3, 6 and 12 months poststroke

Purpose: To better delineate intervention programs, knowledge of the factors that are associated with physical fitness in stroke survivors is crucial. This study aimed to predict cardiorespiratory fitness based on standardized measures along the several dimensions of the International Classification of Functioning, Disability and Health (ICF) model at several time intervals in the first year after stroke. Methods: Forty patients were assessed at 3, 6 and 12 months poststroke. A symptom-limited graded cycle ergometer test was used to assess cardiorespiratory fitness. Outcome variables were VO(2) peak and the Oxygen Uptake Efficiency Slope (OUES). Impairments, activity limitations, participation restrictions, personal and environmental factors were assessed to determine predictive factors. Results: Explained variance at 3, 6 and 12 months poststroke was 39%, 55% and 91% for VO(2) peak and 55%, 63% and 79% for OUES. A strong association between knee muscle strength and cardiorespiratory fitness was found at each measurement time, explaining up to 72 % of the variance in fitness. At 12 months poststroke, functional mobility, body mass index (BMI) and emotional status also contributed to explain variance. Conclusions: Knee muscle strength was found to be a very strong predictor of cardiorespiratory fitness during the first year after stroke and functional mobility became important at 12 months poststroke. [Box: see text].     

Assessment of V̇o2peak and Exercise Capacity After Stroke: A Validity Study of the Human Activity Profile Questionnaire

ObjectiveTo investigate the concurrent validity of the Human Activity Profile (HAP) in individuals after stroke to provide the peak oxygen uptake (V?o_2peak) and the construct validity of the HAP to assess exercise capacity, and to provide equations based on the HAP outcomes to estimate the distance covered in the Incremental Shuttle Walking Test (ISWT).DesignCross-sectional study.SettingUniversity laboratory.ParticipantsIndividuals (N=57) aged 54±11 years who have experienced stroke.InterventionNot applicable.Main Outcome MeasuresAgreement between the V?o_2peak provided by the HAP (lifestyle energy consumption [LEC] outcome, in mL/kg^?1/min^?1) and the criterion standard measure of the V?o_2peak (mL/kg^?1/min^?1), obtained through the symptom-limited Cardiopulmonary Exercise Test (CPET). Correlation between the HAP outcomes (LEC, maximum activity score [MAS], and adjusted activity score [AAS]) and the construct measure: the distance covered (in meters) in the ISWT. An equation to estimate the distance covered in the ISWT was determined.ResultsHigh magnitude agreement was found between the V?o_2peak, in mL/kg^?1/min^?1, obtained by the symptom-limited CPET and the value of V?o_2peak, in mL/kg^?1/min^?1, provided by the HAP (LEC) (intraclass correlation coefficient, 0.75; P<.001). Low to moderate magnitude correlations were found between the distance covered in the ISWT and the HAP (LEC/MAS/AAS) (0.34≤ρ≤0.58). The equation to estimate the distance covered in the ISWT explained 31% of the variability of the ISWT (ISWT_estimated, –361.91+(9.646xAAS)).ConclusionThe HAP questionnaire is a clinically applicable way to provide a valid value of V?o_2peak (in mL/kg^?1/min^?1) and to assess the exercise capacity of individuals after stroke. Furthermore, an equation to estimate the distance covered in the submaximal field exercise test (ISWT) based on the result of the AAS (in points) was provided.     

Autonomic nervous function at rest in aerobically trained and untrained oldermen

Therelationship between aerobictraining, vagal influence on the heart and ageing was examined by assessing aerobic fitness andresting heart rate variability in trained and untrained older men. Subjects were 11 trained cyclistsand runners (mean age=6±61·6 years) and 11 untrained, age-matchedmen (mean age=66±1·2 years). Heart rate variability testing involvedsubjects lying supine for 25 min during which subjects’ breathing was paced andmonitored (7·5 breaths min^?1). Heart rate variability was assessedthrough time series analysis (HRV_ts) of the interbeat interval. Results indicated thattrained older men (3·55±0·21 l min^?1) hadsignificantly (P<0·05) greater VO _2maxthan that of control subjects (2·35±0·15 l min^?1).Also, trained older men (52±1·8 beats min^?1) hadsignificantly (P<0·05) lower supine resting heart rate than that of controlsubjects (65±4·2 beats min^?1). HRV_ts at highfrequencies was greater for trained men (5·98±0·22) than for untrainedmen (5·23±0·32). These data suggest that regular aerobic exercise inolder men is associated with greater levels of HRV_ts at rest.     

Body composition,maximal aerobic performance and inflammatory biomarkers in endurance-trained athletes

This study was designed to examine the relationships between body composition, cardiorespiratory fitness and simultaneously measured inflammatory parameters in endurance-trained athletes. In 20 well-trained rowers (19·0 ± 2·9 years; 185·6 ± 4·8 cm; 85·7 ± 10·8 kg; 17·1 ± 5·1% body fat; maximal oxygen consumption [VO₂max]: 63·9 ± 8·5 ml min⁻¹ kg⁻¹), body composition was measured by dual-energy X-ray absorptiometry and cardiorespiratory fitness by direct VO₂max test. Twelve inflammatory factors [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma (IFN-γ), tumour necrosis factor-alpha, IL-1α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), epidermal growth factor (EGF)] were analysed from serum samples. Serum IFN-γ was related (P<0·05) to fat-free mass (FFM) (r = −0·56) and muscle mass (r = −0·50). The stepwise regression analysis showed that IFN-γ explained 27·5%, and IFN-γ and IL-6 together explained 39·8% of the variability of FFM, while IFN-γ explained 21·1%, and IFN-γ together with EGF explained 36·6% of the variability of muscle mass in male rowers. Serum IL-8 (r = −0·65) and VEGF (r = −0·48) correlated (P<0·05) with VO₂max kg⁻¹. Serum IL-8 explained 38·5% of the variability of VO₂max kg⁻¹. Significant correlations were also found among several inflammatory parameters, indicating that various inflammatory cytokines act on the body as an ensemble. In conclusion, this cross-sectional study in endurance-trained male rowers showed that FFM and muscle mass were negatively correlated with serum IFN-γ level, whereas cardiorespiratory fitness was negatively related to serum IL-8 level.     

Reproducibility of peak oxygen consumption and the impact of test variability on classification of individual training responses in young recreationally active adults

This study investigated whether VO₂peak is reproducible across repeated tests before (PRE) and after (POST) training, and whether variability across tests impacts how individual responses are classified following 3 weeks of aerobic exercise training (cycle ergometry). Data from 45 young healthy adults (age: 20·1 ± 0·9 years; VO₂peak, 42·0 ± 6·7 ml·min^?1) from two previously published studies were utilized in the current analysis. Non‐responders were classified as individuals who failed to demonstrate an increase or decrease in VO₂peak that was greater than 2·0 times the typical error of measurement (107 ml·min^?1) away from zero, while responders and adverse responders were above and below this cut‐off, respectively. VO₂peak tests at PRE (three total) and POST (three total) were highly reproducible (PRE and POST average and single measures ICCs: range 0·938–0·992), with low coefficients of variation (PRE:4·9 ± 3·1%, POST: 4·8 ± 2·7%). However, a potential learning effect was observed in the VO₂peak tests prior to training, as the initial pretraining test was significantly lower than the third (p = 0·010, PRE 1: 2 946 ± 924 ml·min^?1, PRE 3: 3 042 ± 919 ml·min^?1). This resulted in fewer individuals classified as adverse responders for Test 3 compared to any combination of tests that included Test 1, suggesting that a single ramp test at baseline may not be sufficient to accurately classify the VO₂peak response in young recreationally active individuals. Thus, it is our recommendation that the initial VO₂peak test be used as a familiarization visit and not included for analysis.     

Insulin sensitivity in alcoholic cirrhosis

The amount-of-substance rate of glucose metabolism and its sensitivity to the concentration of insulin was quantified in 10 non-diabetic patients with alcoholic cirrhosis of varying severity, using the ‘glucose clamp technique’. Fasting glucose and insulin were 5.4±0.3 mmol/1 and 187±50 μmol/1 (mean ± SEM), respectively. During the hyperglycaemic clamp (blood glucose at 12.5 mmol/1) the glucose metabolic rate (divided by body mass) was 27± 4 μmol·min^?1·kg^?1 at an insulin concentration of 998± 158 pmol/1. Thus the insulin sensitivity of the tissue glucose metabolism was 22±7 m³·min^?1·kg^?1. During the euglycaemic clamp exogenous insulin was given to a concentration of 574± 72 pmol/1. The resulting glucose metabolic rate was 20± 4 μmol·min^?1·kg^?1 and the insulin sensitivity the same as during hyperglycaemia. The calculated systemic delivery rate of insulin (divided by body surface area) was 783± 172 pmol·min^?1·m^?2. Fasting glucagon was 32± 5 pmol/ and only partly depressed by glucose or insulin. In comparison with stated relevant control groups cirrhotics exhibit glucose intolerance characterized by decreased sensitivity to insulin, hyperinsulinaemia due to increased release, and hyperglucagonaemia with decreased suppressibility. There was no relation between clinical or biochemical data of the patients and the above results, suggesting that the abnormal glucose metabolism does not depend directly on the decreased liver function but on a disturbed pancreatic-hepatic-peripheral axis.     

The influence of a fast ramp rate on peak cardiopulmonary parameters during arm crank ergometry

The influence of a very fast ramp rate on cardiopulmonary variables at ventilatory threshold and peak exercise during a maximal arm crank exercise test has not been extensively studied. Considering that short arm crank tests could be sufficient to achieve maximal oxygen consumption (VO₂), it would be of practical interest to explore this possibility. Thus, this study aimed to analyse the influence of a fast ramp rate (20 W min^?1) on the cardiopulmonary responses of healthy individuals during a maximal arm crank ergometry test. Seventeen healthy individuals performed maximal cardiopulmonary exercise tests (Ultima CardiO2; Medical Graphics Corporation, St Louis, USA) in arm ergometer (Angio, LODE, Groningen, The Netherlands) following two protocols in random order: fast protocol (increment: 2 w/6 s) and slow protocol (increment: 1 w/6 s). The fast protocol was repeated 60–90 days after the 1st test to evaluate protocol reproducibility. Both protocols elicited the same peak VO₂ (fast: 23·51 ± 6·00 versus slow: 23·28 ± 7·77 ml kg^?1 min^?1; P = 0·12) but peak power load in the fast ramp protocol was higher than the one in the slow ramp protocol (119 ± 43 versus. 102 ± 39 W, P < 0·001). There was no other difference in ventilatory threshold and peak exercise variables when 1st and 2nd fast protocols were compared. Fast protocol seems to be useful when healthy young individuals perform arm cardiopulmonary exercise test. The usefulness of this protocol in other populations remains to be evaluated.     

Forearm metabolism during infusion of adrenaline: comparison of the dominant and non‐dominant arm

Human skeletal muscle metabolism is often investigated by measurements of substrate fluxes across the forearm. To evaluate whether the two forearms give the same metabolic information, nine healthy subjects were studied in the fasted state and during infusion of adrenaline. Both arms were catheterized in a cubital vein in the retrograde direction. A femoral artery was catheterized for blood sampling, and a femoral vein for infusion of adrenaline. Forearm blood flow was measured by venous occlusion strain‐gauge plethysmography. Forearm subcutaneous adipose tissue blood flow was measured by the local ¹³³Xe washout method. Metabolic fluxes were calculated as the product of forearm blood flow and a‐v differences of metabolite concentrations. After baseline measurements, adrenaline was infused at a rate of 0·3 nmol kg^?1 min^?1. No difference in the metabolic information obtained in the fasting state could be demonstrated. During infusion of adrenaline, blood flow and lactate output increased significantly more in the non‐dominant arm (8·12 ± 1·24 versus 6·45 ± 1·19 ml 100 g^?1 min^?1) and (2·99 ± 0·60 versus 1·83 ± 0·43 μmol 100 g^?1 min^?1). Adrenaline induced a significant increase in oxygen uptake in the non‐dominant forearm (baseline period: 4·98 ± 0·72 μmol 100 g^?1 min^?1; adrenaline period: 6·63 ± 0·62 μmol 100 g^?1 min^?1) while there was no increase in the dominant forearm (baseline period: 5·69 ± 1·03 μmol 100 g^?1 min^?1; adrenaline period: 4·94 ± 0·84 μmol 100 g^?1 min^?1). It is concluded that the two forearms do not respond equally to adrenaline stimulation. Thus, when comparing results from different studies, it is necessary to know which arm was examined.     

Estimation de la consommation pic d��oxyg��ne par la perception de l��effort chez des patients ob��ses et diab��tiques de type 2

Objectives

The main objectives of this study were: 1) to assess the validity of predicting peak oxygen uptake (.VO₂peak) from ratings of perceived exertion (RPE) during a sub-maximal graded exercise test (GXT), in obese patients with diabetes, and 2) to compare the accuracy of predictions obtained from RPE ?? 15 and RPE ?? 17. Materials and methods: Seventeen obese women with type 2 diabetes performed GXT to volitional exhaustion, in which oxygen uptake (.VO₂) and RPE were measured. Individual linear regressions between.VO₂ and RPE, that were collected during the first stages of GXT (RPE ?? 15 and RPE ?? 17), were extrapolated to RPE = 20 in order to predict.VO₂peak. Results: Actual (12.7 ± 3.6 ml.min^?1.kg^?1) and predicted.VO₂peak from RPE ?? 15 and RPE ?? 17 (13.1 ± 3.7 and 13.3 ± 3.8 ml.min^?1.kg^?1, respectively) were not significantly different. The actual.V O₂peak were significantly correlated to the predicted.VO₂peak from RPE ?? 15 and RPE ?? 17 (R = 0.89 and R = 0.92, respectively). The 95% limits of agreement analysis were ?0.4 ± 3.4 and ?0.6 ± 3.0 ml.min^?1.kg^?1 for the predictions from RPE ?? 15 and RPE ?? 17, respectively.

Conclusion

Results suggested that the RPE ?? 15 provide accurate.V O₂peak prediction in obese women with type 2 diabetes. However, the accurate of predictions was improved when the.VO₂peak was predicted from RPE ?? 17. Consequently, RPE may be used to predict.VO₂peak and to decrease the risk of cardio-vascular complications during GXT.     

Mechanical ventilation mode (volume × pressure) does not change the variables obtained by indirect calorimetry in critically ill patients

PurposeThe aim of the study was to analyze the difference between the results obtained by indirect calorimetry (IC) using volume-controlled and pressure-controlled mechanical ventilation in 2 different ventilators and to characterize the variables achieved by IC after well-defined changes in minute volume (Vm).Materials and MethodsProspective study of 20 critically ill patients under volume-controlled (n = 15) or pressure-controlled (n = 5) mechanical ventilation. Three IC measurements of 45 minutes each were taken; values of oxygen consumption (Vo₂), carbon dioxide production (Vco₂), Vm, resting energy expenditure (REE), and respiratory quotient (RQ) were obtained. For the last measurement, Vm was set at 20% above the baseline.ResultsThere were no differences between the results obtained by IC during volume-controlled and pressure-controlled mechanical ventilation. The most relevant changes in the variables obtained by IC before and after intervention in Vm were a significant increase in Vco₂ (from 165 to 177 mL·min^?1; P < .01), a decrease in Paco₂ (from 38.49 to 28.46 mm Hg; P < .01), and a rise in pH (from 7.41 to 7.49; P < .01). There were no alterations in Vo₂, REE, or RQ.ConclusionsVentilators and ventilation modes do not influence the IC measurements. The observed changes have no clinical effects and are reversible, provided that increased Vm is maintained for no longer than 45 minutes.     

Dose-dependent effects of almitrine on hemodynamics and gas exchange in an animal model of acute lung injury

Objective: To determine the dose-response relationship of almitrine (Alm) on pulmonary gas exchange and hemodynamics in an animal model of acute lung injury (ALI).¶Design: Prospective, randomized, controlled study.¶Methods: Twenty anesthetized, tracheotomized and mechanically ventilated (FIO₂ 1.0) pigs underwent induction of ALI by repeated saline washout of surfactant. Animals were randomly assigned to either receive cumulating doses of Alm intravenously (0.5, 1.0, 2.0, 4.0, 8.0 and 16.0 μg · kg^–1· min^–1) for 30 min each (treatment; n = 10) or to receive the solvent malic acid (controls; n = 10).¶Measurements and results: Measurements of pulmonary gas exchange and hemodynamics were performed at the end of each infusion period. Alm < 4.0 μg · kg^–1· min^–1 improved arterial oxygen pressure (PaO₂) (105 ± 9 mmHg for Alm 1.0 vs 59 ± 5 mmHg) and decreased intrapulmonary shunt (Q_s/Q_t) (32 ± 4 % for Alm 1.0 vs 46 ± 4 %) (P < 0.05). Alm ≥ 8.0 μg · kg^–1· min^–1 did not improve pulmonary gas exchange compared to controls. When compared to low doses of Alm < 4.0 μg · kg^–1· min^–1, high doses ≥ 8.0 μg · kg¹· min^–1 decreased PaO₂ (58 ± 11 mmHg for Alm 16.0) and increased Q_s/Q_t (67 ± 10 % for Alm 16.0) (P < 0.05).¶Conclusions: In experimental ALI, effects of almitrine on oxygenation are dose-dependent. Almitrine is most effective when used at low doses known to mimic hypoxic pulmonary vasoconstriction.