Haemodynamic response to exercise in patients with alcoholic liver cirrhosis

Summary. Physical work capacity was evaluated by a multistage bicycle exercise test in 29 patients, 22 men and seven women aged 35–61 years (mean 49) with alcoholic liver cirrhosis and in a sex- and age-matched control group. The maximal work load was reduced in the patient group, mean 122 vs. 186 watts in men (P < 0·001), and 60 vs. 119 watts in women (P < 0·005). Resting heart rate was higher in patients (91 vs. 78 beats × min¹, (P < 0·005), and the maximal heart rate was lower (159 vs. 170 beats × min^-1, (P < 0·001) compared with controls. Thirteen of 29 (45%) patients compared with 5 of 29 (17%) control subjects had an increase in left ventricular ejection fraction of ≤5% during exercise (P < 0·05). The present results suggest that an impaired capacity of the cardiac function to respond adequately to physical stress may at times contribute to the reduced physical work capacity seen in patients with alcoholic liver cirrhosis.     

Middle cerebral artery blood velocity during exercise in patients with atrial fibrillation

Atrial fibrillation limits the ability to increase cardiac output during exercise and may, in turn, affect the exercise-associated elevation in cerebral perfusion. In nine patients with atrial fibrillation (AF) and in five age-matched healthy subjects, middle cerebral artery blood velocity (MCA V_mean) was measured during incremental exercise using the transcranial Doppler. The AF patient group exhibited a lower aerobic capacity than the control group [peak work rate: 106 W (71–153 W; median and range) vs. 129 W (118–159 W) and maximal oxygen uptake: 1·4 l min^–1 (1·0–1·9 l min^–1) vs. 1·7 l min^–1 (1·4–2·2 l min^–1); P = 0·05]. At rest, MCA V_mean was not significantly different between the two groups [43 cm s^–1 (39–56 cm s^–1) vs. 52 cm s^–1 (40–68 cm s^–1)]. During intense cycling, the increase in MCA V_mean was to 51 cm s^–1 (40–78 cm s^–1) (9%) in the AF group and lower than in the healthy subjects [to 62 cm s^–1 (50–81 cm s^–1) 23%; P<0·05], which corresponded with the smaller than expected increase in cardiac output [156% (130–169%) vs. 180%]. Thus, there was a correlation between the increase in MCA V_mean and the ability to increase cardiac output (r² = 0·55, P<0·01). We suggest that, during exercise with a large muscle mass, atrial fibrillation affects the ability to elevate cerebral perfusion, and this results from an impaired ability to increase cardiac output.     

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.     

Measurement of cardiac output with non-invasive Aesculon impedance versus thermodilution

Background: This study compared the non‐invasive thoracic electrical bioimpedance Aesculon^® technique (TEB_Aesculon) with thermodilution (TD) to evaluate whether TEB_Aesculon may offer a reliable means for estimating cardiac output (CO) in humans. Material and method: Cardiac output was measured with TD and TEB_Aesculon in 33 patients, with a mean age ± SEM of 59 ± 2·7 years, that underwent right heart catheterization for clinical investigation of pulmonary hypertension or severe heart failure. Four to five CO measurements were performed with each technique simultaneously in 33 patients at rest, 11 during exercise and seven during NO inhalation. Result: Cardiac output correlated poorly between TEB_Aesculon and TD at rest (r = 0·46, P<0·001), during exercise (r = 0·35, P<0·013) and NO inhalation (r = 0·41, P<0·017). CO was higher for TEB_Aesculon than TD with 0·86 ± 0·14 l min^?1 at rest (P<0·001) and 2·95 ± 0·69 l min^?1 during exercise (P<0·003), but similar during NO inhalation, with a tendency (P<0·079) to be 0·44 ± 0·19 l min^?1 higher for TEB_Aesculon than TD. CO increased from rest to exercise for TEB_Aesculon and TD with 6·11 ± 0·6 l min^?1 (P<0·001) and 3·91 ± 0·36 l min^?1 (P<0·001), respectively; an increase that was higher (P<0·002) for TEB_Aesculon than TD. During NO inhalation, compared to rest, CO decreased for TEB_Aesculon with 0·62 ± 0·11 l min^?1 (P<0·002), but not significantly for TD with 0·21 ± 0·12 l min^?1 (P<0·11). Bland–Altman analysis showed a poor agreement between TEB_Aesculon and TD. Conclusion: TEB_Aesculon overestimated CO compared to TD with ～17% at rest and ～34% during exercise, but the techniques showed similar results during NO inhalation. CO, furthermore, correlated poorly between TEB_Aesculon and TD. TEB_Aesculon may at present not replace TD for reliable CO measurements in humans.     

The exercise heart rate profile in master athletes compared to healthy controls

Endurance exercise protects the heart via effects on autonomic control of heart rate (HR); however, its effects on HR indices in healthy middle‐aged men are unclear. This study compared HR profiles, including resting HR, increase in HR during exercise and HR recovery after exercise, in middle‐aged athletes and controls. Fifty endurance‐trained athletes and 50 controls (all male; mean age, 48·7 ± 5·8 years) performed an incremental symptom‐limited exercise treadmill test. The electrocardiographic findings and HR profiles were evaluated. Maximal O₂ uptake (52·6 ± 7·0 versus 34·8 ± 4·5 ml kg^?1 min^?1; P<0·001) and the metabolic equivalent of task (15·4 ± 1·6 versus 12·2 ± 1·5; P<0·001) were significantly higher in athletes than in controls. Resting HR was significantly lower in athletes than in controls (62·8 ± 6·7 versus 74·0 ± 10·4 beats per minute (bpm), respectively; P<0·001). Athletes showed a greater increase in HR during exercise than controls (110·1 ± 11·0 versus 88·1 ± 15·4 bpm; P<0·001); however, there was no significant between‐group difference in HR recovery at 1 min after cessation of exercise (22·9 ± 5·6 versus 21·3 ± 6·7 bpm; P = 0·20). Additionally, athletes showed a lower incidence of premature ventricular contractions (PVCs) during exercise (0·0% versus 24·0%; P<0·001). Healthy middle‐aged men participating in regular endurance exercise showed more favourable exercise HR profiles and a lower incidence of PVCs during exercise than sedentary men. These results reflect the beneficial effect of endurance training on autonomic control of the heart.     

Pulmonary vasodilatation and augmentation of right ventricular function following terbutaline infusion in severe chronic pulmonary disease

Summary. Twenty patients with a median age of 61 years and a median forced expired volume in 1 s (FEV₁) after bronchodilatating therapy of 0·55 1 were studied in order to measure the effect of intravenous terbutaline on bronchial tone, cardiac function, pulmonary haemodynamics, gas exchange, and oxygen transport capacity during rest and in 10 patients during exercise. Terbutaline infusion during rest resulted in an increase in heart rate from 84 to 103 beats min^-1 (P < 0·01), a decrease in mean systemic arterial pressure from 95 to 80 mmHg (P < 0·02), an unchanged mean pulmonary arterial pressure (18 mmHg), an increase in cardiac index from 2·89 to 3·86 1 min^-1 m^-2 (P < 0·01), an increase in right ventricular ejection fraction from 45 to 53% (P < 0·01), an increase in left ventricular ejection fraction from 63 to 67% (NS), an unchanged arterial oxygen tension, and an increase in calculated oxygen delivery from 533 to 638 ml O₂ min^-1 m^-2 (P < 0·01). During exercise terbutaline infusion resulted in an increase in heart rate from 108 to 120 beats min^-1 (P < 0·05), a decrease in mean systemic arterial pressure from 117 to 106 mmHg (P < 0·01), a decrease in mean pulmonary arterial pressure from 29 to 22 mmHg (P < 0·01), an increase in cardiac index from 4·53 to 4·64 min^-1 m^-2 (NS), an unchanged arterial oxygen tension, and an increase in the calculated oxygen delivery from 834 to 856 ml O₂ min^-1 m^-2 (NS). It was concluded that terbutaline augments right ventricular function: increases right ventricular ejection fraction and decreases right ventricular end-diastolic volume, and further decreases pulmonary vascular resistance without decreasing arterial oxygen tension, and increases oxygen delivery in patients with chronic pulmonary disease during rest and exercise.     

Normal values for QT intervals in ECG during ramp exercise on bicycle

Summary. The relation between QT interval and heart rate during ramp exercise tests on a bicycle was investigated in 37 healthy individuals (21 women) without regular medication and with a normal thallium-201 exercise scintigram (mean age 52–9 ± 8–3, range 38–68). The test started at 20 W and the load increased by 10 W min^-1. A 12-lead ECG was recorded twice every min and mean complexes (during a 15 s period) were calculated by computer. At rest the QT interval (in s) corrected for heart rate (QT_C) for women and men was 0–408 ± 0–004 and 0–399 ± 0–005, respectively, P > 0–05). During exercise there was no difference in QT interval between women and men or between younger (<50 years) and older (> 50 years) individuals. A straight line was used to describe the relation between QT interval and heart rate (beats min^-1; QT = 0–459–12–3xlO^-4*HR). A 95% prediction interval around the regression line was determined using a non-parametric statistical method. When QT_C was calculated using Bazett's formula with a cut-off value of QT_c= 0–46, 19 individuals (11 women) had a prolonged QT interval during exercise. It is concluded that the relation between QT interval and heart rate can during exercise be described by a straight line for normal individuals. It is not valid to use Bazett's formula for correction of QT intervals during ramp exercise tests.     

Beta-blockade and binding of digoxin to skeletal muscle

Summary. The effect of beta-blockade and a 1-h bicycle exercise test on the digoxin concentration in skeletal muscle (thigh) and serum was studied in 10 healthy men, who had ingested 0·5 mg digoxin daily for 2 weeks. Each subject performed two exercise tests at 100–140 W during maintenance digoxin treatment and 24 h after the latest dose. They rested in the supine position for 2·5 h before the exercise. Sixty minutes before the start of the exercise 0·25 mg/kg b.w. propranolol or saline (control) were injected (single-blind). At the end of the exercise the mean heart rate was 30% lower with beta-blockade (P < 0·001). During exercise the mean skeletal muscle digoxin concentration increased by 29% (P<0·01) in the control situation and by 12% (NS) with beta-blockade. The results indicate that propranolol partly inhibits the exercise-induced increase in skeletal muscle digoxin binding. This might be due to inhibition of a catecholamine-induced stimulation of Na⁺-K⁺ATPase during exercise.     

Simultaneous quantification of myocardial perfusion,oxidative metabolism,cardiac efficiency and pump function at rest and during supine bicycle exercise using 1‐11C‐acetate PET – a pilot study

Background: PET using 1‐¹¹C‐acetate (ACE‐PET) applied at rest is used for measuring absolute myocardial blood flow (MBF) and oxidative metabolic rate (k_mono). We evaluated the feasibility of quantitative ACE‐PET during exercise. Methods: Five endurance athletes underwent dynamic PET scanning at rest and during supine bicycle stress. Exercise was maintained at a workload of 120 Watt for 17 min. The rate‐pressure product (RPP) was recorded repeatedly. MBF, k_mono in left (LV) and right (RV) ventricular wall, cardiac output (CO), cardiac efficiency and a lung uptake value reflecting left heart diastolic pressures were calculated from the PET data using previously validated models. Results: MBF increased from 0·71 ± 0·17 to 2·48 ± 0·25 ml min^?1 per ml, LV‐k_mono from 0·050 ± 0·005 to 0·146 ± 0·021 min^?1, RV‐k_mono from 0·023 + 0·006 to 0·087 + 0·014 min^‐1, RPP from 4·7 ± 0·8 to 13·2 ± 1·4 mmHg × min^?1 × 10³ and Cardiac Output from 5·2 ± 1·1 to 12·3 ± 1·2 l min ^?1 (all P < 0·001). Cardiac efficiency was unchanged (P = 0·99). Lung uptake decreased from 1·1 ± 0·2 to 0·6 ± 0·1 ml g^?1 (P < 0·001). Discussion: A number of important parameters related to cardiac function can be quantified non‐invasively and simultaneously with a short scanning protocol during steady state supine bicycling. This might open up new opportunities for studies of the integrated cardiac physiology in health and early asymptomatic disease.     

Ventilation–perfusion inequality and carbon dioxide sensitivity in hypoxaemic chronic obstructive pulmonary disease (COPD) and effects of 6 months of long‐term oxygen treatment (LTOT)

The aim of our study was to find out how blood gas disturbances in stable, eucapnic, severe chronic obstructive pulmonary disease (COPD) patients with an arterial oxygen tension (PaO₂) value of 7·7 (6·1–8·4) kPa are affected by ventilation–perfusion (V_A/Q) relationships and carbon dioxide (CO₂) sensitivity and how these parameters are influenced by 6 months of long‐term oxygen treatment (LTOT). V_A/Q ratios were measured using the multiple inert gas elimination technique (MIGET). Mouth occlusion pressure 0·1 s after onset of inspiration (Pi0·1) and minute ventilation (V_E) were measured to assess respiratory drive response (ΔPi0·1/ΔPCO₂) and hypercapnic ventilatory response (HCVR) to CO₂ rebreathing. At the start of LTOT, a normal median respiratory drive response level of 1·2 (0·2–2·3) cm H₂O/kPa and a low median HCVR as compared with healthy individuals (P<0·001) were found. However, 7·9 (0–29·8)% of the V_E, was directed towards hypoperfused lung areas. The dispersion of ventilation (log SDV; 0·47–1·76), and the dispersion of perfusion (log SDQ; 0·66–1·07) were wider than normal. The PaO₂ level correlated inversely with mean V_A/Q ratio for ventilation (V mean) and shunt. The PaCO₂ level correlated inversely with HCVR and vital capacity. After 6 months of LTOT, no significant changes in daytime blood gas levels, CO₂‐sensitivity or V_A/Q ratios were found. V_E tended to be reduced by 1·0 l min^–1. Conclusions: An elevated V mean and probably shunting are important contributing factors for the reduced PaO₂ and hypercapnic ventilatory response is a major determinant of PaCO₂ in eucapnic stable hypoxaemic COPD. Six months of LTOT does not affect blood gases, CO₂ sensitivity or ventilation–perfusion relationships.     

Commonly used reference values underestimate oxygen uptake in healthy, 50‐year‐old Swedish women

Cardiopulmonary exercise testing (CPET) is the gold standard among clinical exercise tests. It combines a conventional stress test with measurement of oxygen uptake (V_O2) and CO₂ production. No validated Swedish reference values exist, and reference values in women are generally understudied. Moreover, the importance of achieved respiratory exchange ratio (RER) and the significance of breathing reserve (BR) at peak exercise in healthy individuals are poorly understood. We compared V_O2 at maximal load (peakV_O2) and anaerobic threshold (V_O2@AT) in healthy Swedish individuals with commonly used reference values, taking gender into account. Further, we analysed maximal workload and peakV_O2 with regard to peak RER and BR. In all, 181 healthy, 50‐year‐old individuals (91 women) performed CPET. PeakV_O2 was best predicted using Jones et al. (100·5%). Furthermore, underestimation of peakV_O2 in women was found for all studied reference values (P<0·001) and was largest for Hansen‐Wasserman: women had 115% of predicted peakV_O2, while men had 103%. PeakV_O2 was similar in subjects with peak RER of 1–1·1 and RER > 1·1 (2 328·7 versus 2 176·7 ml min^?1, P = 0·11). Lower BR (≤30%) related to significantly higher peakV_O2 (P<0·001). In conclusion, peakV_O2 was best predicted by Jones. All studied reference values underestimated oxygen uptake in women. No evidence for demanding RER > 1·1 in healthy individuals was found. A lowered BR is probably a normal response to higher workloads in healthy individuals.     

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.     

Effects of intense exercise training on endothelium-dependent exercise-induced vasodilatation

To determine whether intense exercise training affects exercise-induced vasodilatation, six subjects underwent 4 weeks of handgrip training at 70% of maximal voluntary contraction. Exercise forearm vascular conductance (FVC) responses to an endothelium-dependent vasodilator (acetylcholine, ACH; 15, 30, 60 μg min^?1) and an endothelium-independent vasodilator (sodium nitroprusside, SNP; 1·6, 3·2, 6·4 μg min^?1) and FVC after 10 min of forearm ischaemia were determined before and after training. Training elicited significant (P<0·001) increases in grip strength (43·4 ± 2·3 vs. 64·1 ± 3·5 kg, before vs. after, mean ± SEM), forearm circumference (26·7 ± 0·4 vs. 27·9 ± 0·4 cm) and maximal FVC (0·4630 ± 0·0387 vs. 0.6258 ± 0·0389 units, P<0·05). Resting FVC did not change significantly with training (0·0723 ± 0·0162 vs. 0.0985 ± 0·0171 units, P>0·4), but exercise FVC increased (0·1330 ± 0·0190 vs. 0.2534 ± 0·0387 units, P<0·05). Before and after the training, ACH increased exercise FVC above the control (no drug) exercise FVC, whereas SNP did not. Training increased (P<0·05) the exercise FVC responses to ACH (0·3344 ± 0·1208 vs. 0.4303 ± 0·0858 units, before vs. after training, 60 μg min^?1) and SNP (0·2066 ± 0·0849 vs. 0.3172 ± 0·0628 units, 6·4 μg min^?1). However, these increases were due to the increase in control (no drug) exercise FVC, as the drug-associated increase in exercise FVC above control did not differ between trials (P>0·6). These results suggest that exercise FVC is increased by both exercise training and stimulating the release of endothelium-dependent vasodilators. However, training does not affect the vascular response to these vasodilators.     

Influence of body adiposity on structural characteristics of skeletal muscle in men and women

The structure of skeletal muscle (SM) can be characterized by quantitative (size) and qualitative (composition) attributes, which are disparately reported to be influenced by body adiposity. This study tests the hypothesis that body adiposity exerts a systematic influence on these muscle characteristics and evaluates the possible functional implications for movements. Lower limb SM volume (VSM) and attenuation (ATTSM), an inverse measure of lipid infiltration in muscle, were determined with computed tomography in 21 men (BMI = 21–36 kg m^?2; age = 31–71 years.) and 18 women (BMI = 19–35 kg m^?2; age = 32–76 years.). After adjusting for age, a multivariate regression analysis revealed that body adiposity positively correlated (P<0·05–0·001) with absolute VSM and cross‐sectional area (CSA) in both genders, while VSM per unit body mass (VSM/BM) decreased with adiposity (P<0·001) in women and was constant in men. ATTSM was higher in men (P<0·05) and decreased (P<0·05) with adiposity in both genders. The product of ATTSM by average muscle CSA (predictor of maximal strength) and by VSM/BM (predictor of maximal dynamic performance) was lower in women (P<0·001) and was reduced by age in both genders (P<0·05–0·01), while obesity had a negative effect (P<0·001) only on the predictor of performance. In conclusion, body adiposity significantly increases SM size and reduces ATTSM. Structural indicators accounting for both quantitative and qualitative characteristics of SM may be useful predictors of the effects of obesity on motor function at different ages. With rising body adiposity and advancing age, women appear mostly affected by the decline of SM features relevant for motor performance.     

Ankle–brachial index after maximum exercise in treadmill and cycle ergometers in athletes

Previous works have focused on the normal ankle and arm pressure response to maximum bicycle exercise or moderate walking tests. The aim of the present work was to compare the normal ankle and arm pressure and ankle–brachial index response to incremental maximum bicycle and treadmill exercise in 13 athletes (11 men, two women, 24 ± 11 years) No difference was found at rest on both ankle pressure 139 ± 21 vs. 163 ± 22 mmHg and ankle–brachial index 1·18 ± 0·09 vs. 1·17 ± 0·10 between bicycle and treadmill tests respectively (mean ± SD). One minute after maximum exercise, no difference in arm pressure was found between bicycle (182 ± 16 mmHg) and treadmill tests (190 ± 17 mmHg), whereas ankle pressure was 139 ± 21 vs. 163 ± 22 mmHg respectively (P<0·05). As a result, a significant difference was found in the ankle–brachial index 0·76 ± 0·10 vs.0·86 ± 0·10 (P<0·05) between bicycle and treadmill ergometers during the first minute of the recovery period. Although performed at comparable workloads, a significant difference was noted between running and cycling tests. Thereby, the limit cut-off point for the diagnosis of lower extremity arterial disease in athletes defined for maximum bicycle tests may not apply to maximum incremental treadmill tests.     

Calculation algorithms alter the breath‐by‐breath gas exchange values when abrupt changes in ventilation occur

The automatic metabolic units calculate breath‐by‐breath gas exchange from the expiratory data only, applying an algorithm (‘expiration‐only’ algorithm) that neglects the changes in the lung gas stores. These last are theoretically taken into account by a recently proposed algorithm, based on an alternative view of the respiratory cycle (‘alternative respiratory cycle’ algorithm). The performance of the two algorithms was investigated where changes in the lung gas stores were induced by abrupt increases in ventilation above the physiological demand. Oxygen, carbon dioxide fractions and ventilatory flow were recorded at the mouth in 15 healthy subjects during quiet breathing and during 20‐s hyperventilation manoeuvres performed at 5‐min intervals in resting conditions. Oxygen uptakes and carbon dioxide exhalations were calculated throughout the acquisition periods by the two algorithms. Average ventilation amounted to 6·1 ± 1·4 l min^?1 during quiet breathing and increased to 41·8 ± 27·2 l min^?1 during the manoeuvres (P<0·01). During quiet breathing, the two algorithms provided overlapping gas exchange data and noise. Conversely, during hyperventilation, the ‘alternative respiratory cycle’ algorithm provided significantly lower gas exchange data as compared to the values yielded by the ‘expiration‐only’ algorithm. For the first breath of hyperventilation, the average values provided by the two algorithms amounted to 0·37 ± 0·34 l min^?1 versus 0·96 ± 0·73 l min^?1 for O₂ uptake and 0·45 ± 0·36 l min^?1 versus 0·80 ± 0·58 l min^?1 for exhaled CO₂ (P<0·001 for both). When abrupt increases in ventilation occurred, such as those arising from a deep breath, the ‘alternative respiratory cycle’ algorithm was able to halve the artefactual gas exchange values as compared to the ‘expiration‐only’ approach.     

Decreased leg glucose uptake during exercise contributes to the hyperglycaemic effect of octreotide

Aim: During prolonged infusion of somatostatin, there is an increase in arterial glucose concentration, and this increase persists even during prolonged exercise. The aim of the study was to measure glucose uptake in the leg muscles during infusion of the somatostatin analogue octreotide before and during leg exercise. Material and methods: Eight healthy male subjects were investigated twice in the fasting state: during 3 h infusion of octreotide [30 ng (kg min)^?1] or sodium chloride with exercise at 50% of maximal VO₂ in the last hour. Glucose uptake and oxygen uptake in the leg were measured using Fick’s principle by blood sampling from an artery and a femoral vein. Blood flow in the leg was measured using the indicator (indocyanine green) dilution technique. Results: After an initial decrease during rest, octreotide infusion resulted in a significant increase in arterial glucose concentrations compared to control conditions during exercise (mean ± SEM: 7·6 ± 0·6 versus 5·6 ± 0·1 mmol l^?1, P<0·01). During rest, octreotide did not change the leg glucose uptake (59 ± 10 versus 55 ± 11 μmol min^?1). In contrast, leg glucose uptake was significantly lower during exercise compared to control conditions (208 ± 79 versus 423 ± 87 μmol min^?1, P<0·05). During exercise, leg oxygen uptake was not different in the two experiments (20·4 ± 1·3 versus 19·5 ± 1·1 μmol min^?1). Conclusion: In conclusion, infusion of octreotide reduced leg glucose uptake during exercise, despite the same leg oxygen consumption and blood flow compared to control conditions. The hyperglycaemic effect of octreotide can partly be explained by the reduction in leg glucose uptake. Furthermore, the results suggest that a certain level of circulating insulin is necessary to obtain sufficient stimulation of glucose uptake in the exercising muscles.     

Sequence effects of combined resistance exercises with step choreography in the same session in women's oxygen uptake during and postexercise

The combination of step choreography (SC) with resistance training exercises (RE) in the same session is common in class fitness rooms populated mainly by women to increase energy expenditure. The aim of this study was to evaluate the differences in the exercise oxygen uptake and postexercise between two different combinations of resistance training exercises and step choreography, regarding the order of execution. Thirteen active women (30·31 ± 4·42 years, 62·02 ± 5·37 kg, 162·65 ± 4·40 cm, 19·14 ± 3·29% body fat) performed two combinations: step choreography before resistance training, where resistance training was divided into two blocks of analysis (10 min each); and step choreography divided into three equal blocks (10 min for each block), before, in the middle and after resistance exercise. There were significant differences (P<0·05) between the two sessions in oxygen uptake postexercise in the period of 0–5 min. A significant increase (P<0·0001) in the oxygen uptake absolute and relative in the heart rate between blocks 1 and 2 of resistance exercise in the two sessions was observed. In the step choreography in blocks, a significant (P = 0·001) decrease between blocks 2 and 3 in the step choreography before resistance exercise and a significant (P<0·05) increase in the heart rate in both sessions between blocks were observed. The combination of step choreography and resistance exercises during the same exercise session is a good strategy to promote an elevation of women's oxygen uptake during and after an exercise session, independent of the sequence used.     

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.     

Effects of endurance training on heart rate and blood pressure variability

Purpose: To study the influences of a 1‐year controlled, randomized endurance exercise training period on heart rate (HR) and blood pressure variability in a representative sample of Finnish men in their late middle age. Methods and results: Subjects were 140 sedentary men aged 53–63 years. The men were randomized into two identical groups: an intervention (EX) and a reference (CO) group. One hundred and twelve of them remained in the final analysis (EX: n=59, CO: n=53). EX trained for 30–60 min three to five times a week with the intensity of 40–60% of maximal oxygen consumption. In EX, 1 year of regular exercise training increased oxygen consumption at respiratory compensation threshold by 11% (P ≤ 0·001) in a maximal cardiorespiratory test. Total power and very low frequency power of R–R interval variability (ms²) tended to increase in the EX group by 26 and 42% and to decrease in the CO group by 13 and 10% (interaction P<0·05 and P<0·01), respectively. There were no significant changes in blood pressure variability. Conclusion: Regular low‐ to moderate‐intensity exercise training could retard the decli‐ning tendency in cardiac autonomic nervous function in older men during 1 year.