Higher Peak Oxygen Uptake Research Articles

Association of Smartwatch-Based Heart Rate and Physical Activity With Cardiorespiratory Fitness Measures in the Community: Cohort Study.

Resting heart rate (HR) and routine physical activity are associated with cardiorespiratory fitness levels. Commercial smartwatches permit remote HR monitoring and step count recording in real-world settings over long periods of time, but the relationship between smartwatch-measured HR and daily steps to cardiorespiratory fitness remains incompletely characterized in the community. This study aimed to examine the association of nonactive HR and daily steps measured by a smartwatch with a multidimensional fitness assessment via cardiopulmonary exercise testing (CPET) among participants in the electronic Framingham Heart Study. Electronic Framingham Heart Study participants were enrolled in a research examination (2016-2019) and provided with a study smartwatch that collected longitudinal HR and physical activity data for up to 3 years. At the same examination, the participants underwent CPET on a cycle ergometer. Multivariable linear models were used to test the association of CPET indices with nonactive HR and daily steps from the smartwatch. We included 662 participants (mean age 53, SD 9 years; n=391, 59% women, n=599, 91% White; mean nonactive HR 73, SD 6 beats per minute) with a median of 1836 (IQR 889-3559) HR records and a median of 128 (IQR 65-227) watch-wearing days for each individual. In multivariable-adjusted models, lower nonactive HR and higher daily steps were associated with higher peak oxygen uptake (VO2), % predicted peak VO2, and VO2 at the ventilatory anaerobic threshold, with false discovery rate (FDR)-adjusted P values <.001 for all. Reductions of 2.4 beats per minute in nonactive HR, or increases of nearly 1000 daily steps, corresponded to a 1.3 mL/kg/min higher peak VO2. In addition, ventilatory efficiency (VE/VCO2; FDR-adjusted P=.009), % predicted maximum HR (FDR-adjusted P<.001), and systolic blood pressure-to-workload slope (FDR-adjusted P=.01) were associated with nonactive HR but not associated with daily steps. Our findings suggest that smartwatch-based assessments are associated with a broad array of cardiorespiratory fitness responses in the community, including measures of global fitness (peak VO2), ventilatory efficiency, and blood pressure response to exercise. Metrics captured by wearable devices offer a valuable opportunity to use extensive data on health factors and behaviors to provide a window into individual cardiovascular fitness levels.

Hospital and intensive care unit stay associated with body mass index affect cardiorespiratory fitness in patients with COVID-19.

The effects of coronavirus disease 2019 (COVID-19) on the cardiorespiratory fitness of hospitalized and obese patients are of utmost relevance. This study aimed to analyze how hospital and intensive care unit (ICU) stay together with body mass index affect cardiorespiratory fitness in patients with COVID-19. 251 participants (males, n = 118; females, n = 133) were assigned to four groups: non-hospitalized COVID-19 patients (n = 65, age: 45.3years), hospitalized COVID-19 patients (n = 63, age: 57.6years), COVID-19 patients admitted to the ICU (n = 61, age: 56.9years), and control group (n = 62, age: 49.8years). An incremental cardiopulmonary exercise test was performed between 3 and 6weeks after medical discharge from hospital. Higher peak oxygen uptake (VO2peak), ventilatory efficiency and power output were found in ICU patients with normal weight (NW) than in overweight (OW) (Mean difference: 0.1L·min-1, -5.5, 29.0W, respectively) and obese (OB) ICU patients (Mean difference: 0.1L·min-1, -5.0, 26.2W, respectively) (p < .05). In NW, OW and OB participants, higher VO2peak and power output were observed in control group compared with non-hospitalized (Mean difference: NW: 0.2L·min-1, 83.3W; OW: 0.2L·min-1, 60.0W; OB: 0.2L·min-1, 70.9W, respectively), hospitalized (Mean difference: NW: 0.2L·min-1, 72.9W; OW: 0.1L·min-1, 58.3W; OB: 0.2L•min-1, 91.1W, respectively) and ICU patients (Mean difference: NW: 0.1L·min-1, 70.9W; OW: 0.2L·min-1, 91.1W; OB: 0.3L·min-1; 65.0W, respectively) (p < .05). The degree of severity of COVID-19, especially identified by hospitalization and ICU stay, together with obesity and overweight were key factors in reducing cardiorespiratory fitness in patients with COVID-19.

Effects of high-intensity interval training on retinal vessel diameters and oxygen saturation in patients with hypertension: A cross-sectional and randomized controlled trial

IntroductionArterial hypertension is a global healthcare burden that affects macrovascular and microvascular structure and function and can promote vascular end-organ damage. This study aimed 1) to evaluate differences in microvascular health between normotensive individuals and patients with arterial hypertension and 2) to assess the effects of short-term high-intensity interval training (HIIT) on microvascular health in the subgroup with arterial hypertension as add-on treatment to antihypertensive medication. MethodsIn the cross-sectional part, central retinal arteriolar (CRAE) and venular diameter equivalent (CRVE), arteriolar-to-venular diameter ratio (AVR), and retinal oxygen saturation (O2-saturation) were investigated in 19 normotensive healthy controls (mean age 56 ± 7 years) and 41 patients with arterial hypertension (mean age 59 ± 7 years). In the subsequent randomized controlled trial (RCT), patients with arterial hypertension were randomized to an intervention group (HIIT 3×/week) or a control group that received standard physical activity recommendations after baseline assessment. Assessments of retinal vessel biomarkers and patients` characteristics were repeated after the intervention period of 8 weeks. ResultsIn the cross-sectional part, individuals with normal blood pressure (BP) showed lower body mass index (BMI), body fat, 24 h systolic and diastolic BP, higher peak oxygen uptake, wider CRAE (174 ± 17 μm vs. 161 ± 17 μm, p = 0.009), and higher AVR (0.84 ± 0.05 vs. 0.79 ± 0.05, p = 0.003) compared to patients with hypertension. In the RCT, patients with arterial hypertension showed reduced BMI and fasting glucose levels after HIIT and control condition. In addition, the intervention group reduced body fat percentage (27.0 ± 5.5 vs. 25.8 ± 6.1, p = 0.023) and increased peak oxygen uptake (33.3 ± 5.7 vs. 36.7 ± 5.1, p < 0.001). No changes in BP were found in either group. The intervention group showed narrower CRVE (β −4.8 [95 % CI, −8.85, −0.81] p = 0.020) and higher AVR (0.03 [0.01, 0.04] p < 0.001) after eight weeks of HIIT compared to the control group. No statistically significant changes in retinal O2-saturation were found in either group. ConclusionShort-term HIIT proved to be an effective treatment to ameliorate hypertension-induced retinal microvascular abnormalities in patients with hypertension. Retinal vessel diameters may prove to be a sensitive biomarker to quantify treatment efficacy at the microvascular level, at the earliest possible stage in patients with hypertension.

Associations between cardiovascular risk factors, disease activity and cardiorespiratory fitness in patients with inflammatory joint disease: a cross-sectional analysis

BackgroundInflammatory joint diseases (IJD) are accompanied by an increased risk of cardiovascular disease (CVD). Cardiorespiratory fitness (CRF) is a modifiable CVD risk factor and low levels of CRF associate with an elevated CVD risk. This study aimed to investigate the associations between CVD risk factors, disease activity and CRF in patients with IJD and to explore differences between patients with normal versus low levels of CRF.MethodsCRF was measured as peak oxygen uptake (VO2peak) with a cardiopulmonary exercise test. Participants were also evaluated for: Body composition, blood pressure, blood lipids, inflammatory markers and disease activity. Patient-reported use of cigarettes/snuff, medication, disease duration, pain, fatigue, CVD history, habitual physical activity and exercise beliefs and self-efficacy were collected by questionnaire. Cross-sectional associations between CVD risk factors, disease-related factors and CRF were analyzed by multiple linear regression. CRF was categorized to normal CRF (VO2peak ≥ 80%) or low CRF (VO2peak < 80%) according to age- and gender-stratified reference data. Differences in demographic, CVD and disease-related factors between patients with normal versus low CRF were explored.ResultsIn 60 Norwegian patients with IJD [34 females, age 59 years (IQR: 52–63)], mean VO2peak was 30.2 (± 6.9) mL/kg/min, corresponding to 83% (± 18) of normative reference values. Age (coefficient: − 0.18 years, p = 0.01) and fat mass (coefficient: − 0.67 %, p < 0.001) were inversely associated with CRF, while physical activity index (coefficient: 0.13 points, p = 0.05) was positively associated with CRF (R2 = 0.66). There were no significant associations between CRF, classical CVD risk factors and disease-related variables. Compared to patients with low CRF (n = 30), patients with normal CRF (n = 30) had higher peak oxygen uptake (+ 9.4 mL/kg/min, p < 0.001), high-density lipoprotein cholesterol (+ 0.5 mmol L−1, p < 0.001), and exercise self-efficacy (+ 6.9, p < 0.01) as well as lower fat mass (− 8.7%, p < 0.001), resting heart rate (− 8.0 beats/min, p < 0.01) and triglycerides (− 0.5 mmol L−1, p < 0.01).ConclusionsIn this sample of IJD-patients, age, fatmass and physical activity level were associated with CRF. CRF was lower than reference values and patients with normal CRF presented with a more favorable health profile. There is a continued need for exercise interventions to improve CRF in patients with IJD.Trial registration: NCT04922840.

Pulmonary Vascular Pressures and Gas Exchange Response to Exercise in Heart Failure With Preserved Ejection Fraction

Elevated left ventricular filling pressure (measured as mean pulmonary capillary wedge pressure) at rest or with exercise is diagnostic of heart failure with preserved ejection fraction. However, the capacity of the right ventricle to compensate for a high mean pulmonary capillary wedge pressure and thus maintain an appropriate transpulmonary gradient (TPG) and perfusion of the pulmonary capillaries is likely an important contributor to gas exchange efficiency and exercise capacity. Therefore, this study aimed to determine whether a higher TPG at peak exercise is associated with superior exercise capacity and gas exchange. Gas exchange data from dyspneic patients referred for exercise right heart catheterization were retrospectively analyzed and patients were split into two groups based on TPG. Patients with a higher TPG at peak exercise had a higher peak VO2 (1025 ± 227 vs 823 ± 276, P = .038), end-tidal partial pressure of carbon dioxide (42.2 ± 7.9 vs 38.0 ± 4.7, P = .044), and gas exchange estimates of pulmonary vascular capacitance (408 ± 90 vs 268 ± 108, P = .001). A higher TPG at peak exercise correlated with a higher peak oxygen uptake, O2 pulse, and stroke volume (R = 0.42, 0.44 and 0.42, respectively, all P < 0.05). These findings indicate that a greater TPG with exercise might be important for improving exercise capacity in heart failure with preserved ejection fraction.

The Effects of a Patient and Provider Co-Developed, Behavioral Physical Activity Intervention on Physical Activity, Psychosocial Predictors, and Fitness in Individuals with Spinal Cord Injury: A Randomized Controlled Trial.

Physical activity (PA) interventions in people with spinal cord injury (SCI) have been limited by a shortage of (1) evidence for sufficient increases in unsupervised PA to improve aerobic fitness and (2) stakeholder involvement in intervention design. This study examined the effects of a theory-based PA intervention, developed in collaboration with nearly 300 stakeholders, on PA levels, aerobic fitness, and psychosocial predictors of PA among individuals with SCI. A randomized controlled trial (RCT) was conducted with 28 men and women with chronic SCI (age 45.0 ± 11.5years, years post-injury 16.4 ± 12.4). Participants randomized to the intervention group (n = 14) received an introductory personal training session followed by eight weekly 15-min PA behavioral coaching sessions per week. PA was assessed using self-report and accelerometers. Aerobic fitness and psychosocial predictors of exercise were evaluated using an incremental exercise test and survey methods, respectively. At post-intervention, controlling for baseline, the intervention group showed fivefold greater self-reported moderate to vigorous physical activity [mean difference 247.9min/day; 95% confidence interval (CI) 92.8-403.1; p = 0.026, d = 1.04], 17% greater accelerometer-measured PA (mean difference 3.9 × 105 vector magnitude counts; 95% CI 1.1 × 104-7.7 × 105; p = 0.014, d = 0.31), and 19% higher peak oxygen uptake (VO2Peak; mean difference 0.23L/min; 95% CI 0.12-0.33; p < 0.001, d = 0.54) compared with the control group. Mean values of psychosocial predictors of PA were also significantly improved in the intervention group compared with controls. To our knowledge, this co-created behavioralintervention produced the largest effect size to date for change in self-reported PA in an RCT involving people with physical disability. This is also the first RCT in people with SCI to demonstrate that abehavioral intervention can sufficiently increase unsupervised PA to improve aerobic fitness. ClinicalTrials.gov, NCT03111030, 12 April 2017, https://clinicaltrials.gov/ct2/show/NCT03111030?term=NCT03111030&rank=1 .

Comprehensive Exercise Capacity and Quality of Life Assessments Predict Mortality in Patients with Pulmonary Arterial Hypertension.

The 6-minute walk test (6MWT) and cardiopulmonary exercise test (CPET) are exercise tests associated with physical function, quality of life and hemodynamic data in patients with pulmonary arterial hypertension (PAH). This study was conducted to assess correlations between exercise capacity, quality of life and disease functional classification, and to analyze the value of comprehensive assessments in predicting mortality in patients with PAH. Fifty-four patients with PAH were enrolled. Comprehensive assessments including exercise capacity evaluated using the 6MWT and CPET, and health-related quality of life evaluated using the Short Form 36 (SF-36) questionnaire were performed in all participants. The patients were followed for 2 years with the end point of mortality. The survivors had a longer 6-minute walking distance, higher peak oxygen uptake and higher physical component score of the SF-36 than the non-survivors. In addition, exercise capacity combined with SF-36 predicted 2-year mortality in the patients with PAH. The patients with lower peak oxygen uptake (peak VO2 < 11.03 mL/kg/ min) and lower physical component score (score < 44.54) had a higher mortality rate than those with a higher peak VO2 and higher physical component score (adjusted hazard ratio = 19.95, p = 0.011). Comprehensive assessments of exercise capacity and quality of life can be used to predict 2-year mortality in patients with PAH.

Impact of Lifelong Exercise Training Dose on Ventricular-Arterial Coupling.

The dynamic Starling mechanism, as assessed by beat-by-beat changes in stroke volume and left ventricular end-diastolic pressure, reflects ventricular-arterial coupling. It deteriorates with age, and is preserved in highly trained masters athletes. Currently, it remains unclear how much exercise over a lifetime is necessary to preserve efficient ventricular-arterial coupling. The purpose of this study was to assess the dose-dependent relationship between lifelong exercise training and the dynamic Starling mechanism in healthy seniors. One hundred two seniors were recruited and stratified into 4 groups based on 25 years of exercise training history: sedentary subjects (n=27, <2 sessions/week), casual exercisers (n=25, 2-3 sessions/week), committed exercisers (n=25, 4-5 sessions/week), and competitive Masters Athletes (n=25, 6-7 sessions/week). The dynamic Starling mechanism was estimated by transfer function gain between beat-by-beat changes in diastolic pulmonary artery pressure, a surrogate for left ventricular end-diastolic pressure, and stroke volume index. The transfer function gain of pulmonary artery pressure-stroke volume index was markedly enhanced in committed and competitive exercisers compared with more sedentary seniors and correlated with higher peak oxygen uptake (Vo2) and lower left ventricular stiffness. The power spectral density of pulmonary artery pressure was greater in sedentary adults than in committed and competitive exercisers, whereas the power spectral density of stroke volume index was greater in competitive exercisers than in the other groups. There is a graded, dose-dependent improvement in ventricular-arterial coupling with increasing amounts of lifelong regular exercise in healthy older individuals. Our data suggest that the optimal dose of lifelong endurance exercise to preserve ventricular-arterial coupling with age appears to be at least 4 to 5 sessions per week.

The interrelationship between muscle oxygenation, muscle activation, and pulmonary oxygen uptake to incremental ramp exercise: influence of aerobic fitness.

We investigated whether muscle and ventilatory responses to incremental ramp exercise would be influenced by aerobic fitness status by means of a cross-sectional study with a large subject population. Sixty-four male students (age: 21.2 ± 3.2 years) with a heterogeneous peak oxygen uptake (51.9 ± 6.3 mL·min(-1)·kg(-1), range 39.7-66.2 mL·min(-1)·kg(-1)) performed an incremental ramp cycle test (20-35 W·min(-1)) to exhaustion. Breath-by-breath gas exchange was recorded, and muscle activation and oxygenation were measured with surface electromyography and near-infrared spectroscopy, respectively. The integrated electromyography (iEMG), mean power frequency (MPF), deoxygenated [hemoglobin and myoglobin] (deoxy[Hb+Mb]), and total[Hb+Mb] responses were set out as functions of work rate and fitted with a double linear function. The respiratory compensation point (RCP) was compared and correlated with the breakpoints (BPs) (as percentage of peak oxygen uptake) in muscle activation and oxygenation. The BP in total[Hb+Mb] (83.2% ± 3.0% peak oxygen uptake) preceded (P < 0.001) the BP in iEMG (86.7% ± 4.0% peak oxygen uptake) and MPF (86.3% ± 4.1% peak oxygen uptake), which in turn preceded (P < 0.01) the BP in deoxy[Hb+Mb] (88.2% ± 4.5% peak oxygen uptake) and RCP (87.4% ± 4.5% peak oxygen uptake). Furthermore, the peak oxygen uptake was significantly (P < 0.001) positively correlated to the BPs and RCP, indicating that the BPs in total[Hb+Mb] (r = 0.66; P < 0.001), deoxy[Hb+Mb] (r = 0.76; P < 0.001), iEMG (r = 0.61; P < 0.001), MPF (r = 0.63; P < 0.001), and RCP (r = 0.75; P < 0.001) occurred at a higher percentage of peak oxygen uptake in subjects with a higher peak oxygen uptake. In this study a close relationship between muscle oxygenation, activation, and pulmonary oxygen uptake was found, occurring in a cascade of events. In subjects with a higher aerobic fitness level this cascade occurred at a higher relative intensity.

Feedback control of oxygen uptake profiles during robotics‐assisted treadmill exercise

Gait rehabilitation robots have potential for cardiovascular rehabilitation of patients with neurological deficits. A novel method was developed to guide exercise intensity by feedback control of oxygen uptake rate with a focus on tracking ramps as typically applied in maximal exercise testing. This approach is important as prior observations have noted a non-linear oxygen uptake response to increasing work rate, whereas a linear progression of exercise intensity is desirable. The proposed oxygen-uptake controller has embedded within it a human-in-the-loop feedback system for control of mechanical work rate which takes its target work rate from the automatic oxygen uptake control loop. Results of step and ramp tracking of target oxygen-uptake profiles, and disturbance rejection tests, demonstrated the technical feasibility and accuracy of the approach. Comparison with open-loop tests demonstrated clearly that the feedback system linearises the oxygen-uptake response and that linear progression of exercise intensity leads to higher peak oxygen uptake values. Further work will focus on clinical feasibility and the potential for cardiovascular rehabilitation in patients with neurological deficits.

Increased aortic blood pressure augmentation in patients with congenital heart defects — A cross-sectional study in 1125 patients and 322 controls

ObjectiveMultiple studies have demonstrated the predictive value of arterial stiffness parameters like augmentation index (AIx) for cardiovascular events, the onset of hypertension, and the progression of heart failure. There is evidence that arterial stiffness is increased in some diagnostic subgroups of patients with congenital heart defects (CHD). This study aims to investigate AIx in a large cross-sectional cohort of patients with CHD. Patients and methodsWe prospectively examined 1125 consecutive patients with various congenital heart defects (27.3±12.1years, 464 female) referred for routine cardiopulmonary exercise testing (CPET) in our institution, and 322 healthy volunteers (29.4±18.4years, 165 female). AIx was estimated in supine position using the oscillometric Vicorder device (SMT medical, Würzburg, Germany). Afterward patients performed a CPET. ResultsIn multivariable regression, presence of a CHD emerged as independent risk factor for higher AIx (p<.001). AIx was also higher in older (p<.001), smaller (p<.001) and heavier (p<.001) patients and in females (p=.008).Patients with aortic stenosis (p<.001), Tetralogy of Fallot (p<.001), transposition of the great arteries after atrial switch (p<.001) or Rastelli procedure (p=.013) and after Fontan procedure (p=.002) had higher AIx. Higher peak oxygen uptake (p<.001) and an ACE-inhibitor (p=.088) were associated with a lower AIx. ConclusionsAIx is increased in patients with CHD. Several diagnostic subgroups are at risk. A better understanding of pathophysiologic mechanisms, genetic predisposition, the role of surgical aortic scars or implanted conduits/patches and medication is needed to define the value of AIx for further cardiovascular risk assessment in this cohort.

The physiological and biomechanical contributions of poling to roller ski skating

Poling is considered to make a significant contribution to cross-country skiing with the skating technique. To better understand this contribution, the current investigation compared roller ski skating on a treadmill with the so-called G3 skating technique with (G3-P) and without poling (G3-NP). Seven male elite skiers performed 5-min submaximal tests at 8, 12, and 15 km h(-1), as well as an incremental test to exhaustion with both techniques on a 5 % incline. Ventilatory variables were assessed by open-circuit indirect calorimetry and three-dimensional kinematics analyzed using the Qualisys Pro Reflex system. G3-P was associated with approximately 15 % higher peak velocity and 10 % higher peak oxygen uptake than G3-NP in the incremental test (both P < 0.01). All ventilatory variables, as well as heart rate and blood lactate concentration were lower with G3-P as compared to G3-NP at 12 and 15 km h(-1) (all P < 0.01). Gross efficiency (i.e., the ratio of work rate to metabolic rate) at 12 km h(-1) was higher in G3-P (14.9 %) than G3-NP (13.5 %) (P < 0.01). Moreover, with G3-P cycle time and length were both 30 % longer, with correspondingly reduced cycle rates (all P < 0.01). In addition, the ski gliding and swing phases were longer and the angle between the skis smaller with G3-P (both P < 0.01), whereas the push-off time was independent of technique and velocity. Taken together, these results indicate that poling makes an important contribution to propulsion and velocity during ski skating, specifically by enhancing peak oxygen uptake, skiing efficiency and associated biomechanical variables.

Effect of metformin on substrate utilization after exercise training in adults with impaired glucose tolerance

Metformin attenuates the higher insulin sensitivity that occurs with exercise training. Sixteen people with prediabetes trained for 10 weeks while taking metformin (n = 8) or placebo (n = 8). Substrate utilization was assessed using glucose kinetics and indirect calorimetry. After training, exercise whole-body fat oxidation was higher and glycogen use lower (p < 0.05), with no differences between groups. Blood glucose use was unchanged. Training-induced enhancement of insulin sensitivity (clamp) correlated with higher peak oxygen uptake (r = 0.70; p < 0.05), but was independent of glucose kinetic and substrate metabolism.

One-arm maximal strength training improves work economy and endurance capacity but not skeletal muscle blood flow

Maximal strength training with a focus on maximal mobilization of force in the concentric phase improves endurance performance that employs a large muscle mass. However, this has not been studied during work with a small muscle mass, which does not challenge convective oxygen supply. We therefore randomized 23 adult females with no arm-training history to either one-arm maximal strength training or a control group. The training group performed five sets of five repetitions of dynamic arm curls against a near-maximal load, 3 days a week for 8 weeks. This training increased maximal strength by 75% and improved rate of force development during both strength and endurance exercise, suggesting that each arm curl became more efficient. This coincided with a 17–18% reduction in oxygen cost at standardized submaximal workloads (work economy), and a 21% higher peak oxygen uptake and 30% higher peak load during maximal arm endurance exercise. Blood flow assessed by Doppler ultrasound in the axillary artery supplying the working biceps brachii and brachialis muscles could not explain the training-induced adaptations. These data suggest that maximal strength training improved work economy and endurance performance in the skeletal muscle, and that these effects are independent of convective oxygen supply.

PGC-1α: important for exercise performance?

since the identification of the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α as a factor interacting with PPARγ in brown adipose tissue (BAT) ([12][1]), it has become clear that PGC-1α plays important roles in regulating several cellular processes

Exercise performance during losartan‐ or atenolol‐based treatment in hypertensive patients with electrocardiographic left ventricular hypertrophy (a LIFE substudy)

The objective of the study was to assess the influence of left ventricular (LV) hypertrophy regression on exercise capacity in hypertensive patients. Doppler echocardiography was performed at rest and during exercise in 51 patients with electrocardiographic LV hypertrophy before and after 1 year of randomized blinded losartan‐ or atenolol‐based antihypertensive treatment. After 1 year, blood pressure was comparably reduced by 32/14 and 27/13 mmHg, respectively, in the losartan and atenolol groups, but the atenolol group had higher mean LV mass index (118 vs 103 g/m2) and lower LV ejection fraction (61% vs 67%) and midwall shortening (15.8% vs 16.8%) (all p<0.05). Resting diastolic Doppler indices remained unchanged and did not differ between the groups. Peak oxygen uptake during exercise was virtually unchanged after 1 year and did not differ between the groups in spite of a lower peak exercise heart rate in atenolol‐treated patients. In multivariate analysis, higher peak oxygen uptake at 1 year was associated with lower body mass index, and higher systolic blood pressure and shorter isovolumic relaxation time at peak exercise (multiple R2 = 0.51, p<0.01), while age, gender, heart rate increase during exercise, reduction in LV mass and study treatment did not enter. In conclusion, reduction in blood pressure and LV mass induced by losartan or atenolol treatment was not accompanied by improved exercise capacity after 1 year. The results may be explained by persistent impairment of myocardial relaxation influencing exercise capacity.

Effect of exercise mode on oxygen uptake and blood gases in COPD patients

Patients with chronic obstructive pulmonary disease (COPD) are characterised by decreased exercise tolerance, and, more variably, exercise induced hypoxaemia (EIH). Evaluation of physical work capacity and physiological responses to exercise may be performed by various procedures, but there are diverging opinions as to which exercise test should be preferred. In the current study, oxygen uptake and arterial blood gases in COPD patients have been compared during sub-maximal and maximal exercise on treadmill and ergometer bicycle. Treadmill exercise resulted in higher peak oxygen uptake than bicycle exercise (1111±235 vs. 987±167 ml min −1, P<0.02), while the plasma lactate levels were higher during cycling (1.8±0.8 vs. 3.8±1.7 mmol l −1, P<0.001). Neither carbon dioxide output, ventilation, nor rate of perceived exertion (Borg RPE scale) showed significant differences between the two modes of exercise. The EIH during both maximal (Δ Sa,O 2=−5.6±4.2 vs. −3.4±5.1%) and sub-maximal exercise was more pronounced during treadmill walking than during cycling. The present study indicates that the VO 2peak in COPD patients is higher, the maximal lactate concentrations lower and the development of EIH more pronounced when exercise testing is performed on a treadmill than on a bicycle ergometer.

Aerobic exercise physiology in a professional rugby union team

Introduction: In professional rugby, different positional roles may require different levels of aerobic fitness. Forward and backline players from a team of elite rugby players were tested to evaluate the differences between the two groups. Methods: 28 male players, 15 backs and 13 forwards, underwent maximal treadmill cardiopulmonary exercise testing (CPX), lung spirometry, a 3 km timed run, and body fat measurement. Results: Peak oxygen uptake was higher in backs than in forwards (peak VO 2 48.3±2.1 vs. 41.2±2.7 ml kg −1 min −1, P<0.05) with no significant difference in peak respiratory exchange ratio (1.08±0.02 vs. 1.07±0.02, P=NS), exercise time (1306±39.7 vs. 1217±25.1 s, P=NS) or time for 3 km run (667.5±14.1 vs. 699.0±20.7 s, P=NS). However, the forwards were taller and heavier (height 190.2±2.2 vs. 179.5±1.3 cm, P<0.001, body mass 104±2.4 vs. 86.3±1.7 kg, P<0.0001) and had a higher fat content (body fat percentage 12.8±0.8 vs. 9.7±0.6%, P<0.01) and forced expiratory volume in 1 s (FEV1, 4.9±0.1 vs. 4.5±0.2 l, P<0.05). There was a significant negative correlation between peak VO 2, 3 km run time ( r=−0.45, P<0.05) and weight ( r=−0.54, P<0.003) for all subjects. Conclusion: Backline players have a higher peak oxygen uptake per kilogram than forwards, although the cardiopulmonary exercise test duration, degree of anaerobic metabolism and 3 km run time are not significantly different. These results could be due to the two groups’ different body structure, being shorter, lighter and having a lower percentage body fat. These differences, which are likely to be a result of selection for specific roles in the game, should be taken into account when evaluating aerobic fitness within a rugby team.

Impact of diastolic doppler indices on exercise capacity in hypertensive patients with electrocardiographic left ventricular hypertrophy (a LIFE substudy)

To assess whether Doppler evidence of impaired early diastolic relaxation during exercise is associated with lesser exercise capacity in hypertensive patients. Single center addition to the echocardiographic substudy in the Losartan Intervention For Endpoint (LIFE) reduction in hypertension study. University hospital out-patient clinic. A total of 60 patients (29 women and 31 men) with essential hypertension and electrocardiographic LV hypertrophy. Assessment of Doppler echocardiography and ergospirometry during semi-upright bicycling. Exercise capacity and its relation to diastolic Doppler indices at rest and during exercise. Average resting blood pressure was 181/97 +/- 18/9 mmHg, LV mass/body surface area 127 +/- 26 g/m2, midwall shortening 16 +/- 2%, and isovolumic relaxation time (IVRT) and transmitral early to atrial filling velocity (E/A) ratio 121 ms and 0.80, respectively. Exercise capacity, assessed as peak oxygen uptake and exercise load at exhaustion in all patients, were 20 and 25% higher, respectively, in men than women (both P < 0.01). In multivariate analysis, higher peak exercise load was related to male gender, higher E/A ratio at rest, greater reduction in IVRT during exercise and higher peak exercise heart rate (multiple R2 = 0.59, P < 0.01). Younger age, greater reduction in IVRT during exercise, higher midwall shortening and peak exercise heart rate were associated with higher peak oxygen uptake (multiple R2 = 0.47, P < 0.01). Diastolic LV performance significantly influences exercise capacity in hypertensive patients with LV hypertrophy. Impaired exercise capacity is more strongly associated with blunted reduction in IVRT during exercise than with lower E/A ratio at rest.

Cardiorespiratory function, flexibility, and body composition among geriatric Tai Chi Chuan practitioners

Objective: To evaluate the health-related fitness of geriatric Tai Chi Chuan (TCC) practitioners. Design: Case-control study of a TCC group and a group of sedentary controls. Setting: Research project at a hospital-based exercise physiology laboratory. Participants: Seventy-six community-dwelling senior persons (mean age 69.3 ± 3.9yr), a TCC group that included 22 men and 19 women and a control group of sedentary subjects that included 18 men and 17 women with matched age and body size. Intervention: The TCC group had practiced TCC regularly for 11.8 ± 5.6 years, with an exercise frequency of 4.3 ± 1.3 times per week. Each session included 20 minutes of warm-up, 24 minutes of TCC training, and 10 minutes of cool-down. Exercise intensity was estimated to exceed 70% of maximal heart rate (HRmax). Main Outcome Measure: Breath-by-breath measurement of cardiorespiratory function was obtained during the incremental exercise of leg cycling. Flexibility of thoracic/lumbar spine was measured by an electronic inclinometer. Percentages of body fat were calculated from biceps and subscapular skinfolds. Results: In the peak exercise, men in the TCC group showed 19% higher peak oxygen uptake (V̇ o 2peak) in comparison with their sedentary counterparts (26.9 ± 4.7mL/kg/min vs 21.8 ± 3.1 mL/kg/min). Women in the TCC group also showed 18% higher V̇ o 2peak than in the sedentary group (20.1 ± 2.9mL/kg/min vs 16.5 ± 2.0mL/kg/min). The TCC group also showed higher oxygen uptake at the ventilatory threshold. In addition, the TCC practitioners were characterized by greater flexibility and lower percentage of body fat in comparison with their sedentary counterparts. Conclusion: It is concluded that TCC training has benefits for health-related fitness, and it may be prescribed as a suitable conditioning exercise for the elderly.