Effect of High Intensity Exercise on Peak Oxygen Uptake and Endothelial Function in Long‐Term Heart Transplant Recipients

Coronary allograft vasculopathy is a well‐known long‐term complication after cardiac transplantation. Endothelial dysfunction is involved and may be prevented by aerobic exercise. The purpose of this study was to examine whether high intensity aerobic exercise improves peak oxygen uptake (VO_{2 peak}) and endothelial function in heart transplant (HT) recipients. Twenty‐seven long‐term HT recipients were randomized to either 8‐weeks high intensity aerobic exercise or no training. Flow mediated dilation of the brachial artery (FMD) was measured by ultrasound and VO_{2 peak} by the analysis of expired air. Blood pressure and biomarkers were measured before and after 8 weeks. VO_{2 peak} increased significantly in the exercise group (VO_{2 peak} 23.9 ± 1.79 to 28.3 ± 1.63 mL/kg/min compared to controls (VO_{2 peak} 24.6 ± 1.38 to 23.4 ± 1.58, p < 0.001 exercise vs. control).FMD increased in the exercise group compared to controls (8.3 ± 1.1% to 11.4 ± 1.2% vs. 5.6 ± 1.0% to 5.3 ± 1.7%, p = 0.024). No increase in nitroglycerin‐induced vasodilation was observed. Systolic blood pressure fell in the exercise group (142 ±4.2 mmHg to127 ± 3.4 mmHg, p = 0.01) and was unchanged in controls (141 ± 4.2 mmHg to 142 ±6.4 mmHg, NS). High intensity aerobic exercise reduces systolic blood pressure and improves endothelial function in HT recipients.     

Interval training does not modulate diastolic function in heart transplant recipients

Objectives. This study investigates the effect of aerobic interval training on diastolic function at rest and during exercise in stable heart transplant (HTx) recipients. Design. Twenty-three stable HTx recipients (74% males, mean age 50 ± 14.9 years) were recruited to a training programme. Intervention was 8 weeks intensive training or control in a randomized controlled design. Results. At baseline, participants had normal or mild diastolic dysfunction at rest. During exercise, mean E/e′ increased from 9.0 (± 2.8) to 12.8 (± 7.7) (p = 0.09), E/A increased from 2.1 (± 0.6) to 2.6 (± 0.7) (p = 0.02), and deceleration time decreased by over 50 ms, all markers of increased filling pressure. There were no correlations between diastolic function and VO_2peak at baseline. After intervention VO_2peak increased from 23.9 (± 4.5) to 28.3(± 6) ml/kg/min in the training group (difference between groups p = 0.0018). No consistent pattern of improvement in diastolic function at rest or during exercise was seen. Conclusion. The study does not support a role of diastolic dysfunction in the limited exercise capacity of HTx recipients and suggests that in these patients peripheral factors are of greater importance.     

Adaptation to reduced lung function in children and young people with spinal deformity

BackgroundSevere scoliosis can affect respiratory function in growing patients and produce cardiopulmonary complications, leading to significant morbidity. The development of spinal deformity may impact on young patients’ level of function and reported quality of life (QOL). The aim of this study was to investigate the relationship between lung function, exercise capacity and quality of life in young patients with spinal deformity.MethodsThis is a retrospective analysis of 104 patients (31% male, 69% female with mean age 14.9yrs). 77% of patients had an adolescent idiopathic scoliosis, with the remainder having other scoliosis diagnoses or Scheuermann’s kyphosis. Principal outcomes included Spirometry [FEV₁, FVC], Whole Body Plethysmography, Cardiopulmonary Exercise Testing [CPET] and patient outcome questionnaires (with SRS-22). CPET measures included maximal exercise capacity [VO_2peak] as well as VO₂ at ventilatory threshold [VT] expressed as %predicted VO_2max-a measure of physical conditioning, and minute ventilation [V_E] from which breathing reserve [BR] could be calculated.ResultsMean (±SD) main thoracic scoliosis was 59.9⁰ (±15.2⁰), and mean kyphosis in those with Scheuermann’s condition was 95.3⁰ (±11.5⁰). No correlation was elicited between FEV₁ or FVC (%predicted) and VO_2peak (%predicted) in this patient cohort. Greater thoracic curves were associated with lower FEV₁ (%predicted), r = −0.343, p = 0.001, FVC (%predicted), r = −0.307, p = 0.003 and BR (%) at the end of exercise (r = −0.-0.459, p < 0.001). The patient cohort had a mean (sd) VO₂peak of 98(17) %predicted, with greater VO₂peak levels recorded in female subjects, those of younger age and those with higher scoliosis angles. Those with better lung function [FEV₁ (%predicted)] had better BR (%) at the end of exercise (r = 0.483, p < 0.001). SRS-22 scores correlated significantly with VO_2peak (%predicted) (total SRS-22 versus VO_2peak (%predicted), r = 0.336, p = 0.002).ConclusionLarger thoracic scoliotic curves are associated with poorer lung function but better exercise capacity, likely related to higher levels of physical conditioning. Higher QOL scores were recorded in patients who had greater VO_2peak levels, suggesting that exercise capacity may be a protective factor for emotional well-being in patients with spinal deformity.     

Enhanced Exercise Performance and Survival Associated With Evidence of Autonomic Reinnervation in Pediatric Heart Transplant Recipients

Following heart transplantation (HTx), loss of autonomic input to the allograft results in elevated resting heart rate (HR) and decreased chronotropic reserve. As enhanced exercise capacity and HR recovery post exercise are suggestive of reinnervation in pediatric cohorts, we used heart rate variability (HRV) analysis to assess autonomic reinnervation in pediatric HTx recipients. Pediatric patients transplanted between 1996 and 2010 and with serial 24‐hour Holter recordings post‐HTx were analyzed for HRV using time and frequency domain measures. Of 112 patients, 68 (57%) showed evidence of autonomic reinnervation that was not associated with age at HTx. Evidence of reinnervation was associated with a significant increase in low‐frequency power spectrum (p<0.001), suggesting sympathetic reinnervation. Patients with evidence of reinnervation showed higher percent‐predicted maxVO₂ on performing an exercise test (+10.2 ± 3.6%, p = 0.006) and improved HR recovery at 3 minutes (?11.4 ± 3.9 bpm, p = 0.004), but no difference in percent‐predicted maximal HR. Cox hazards modeling using presumed sinus reinnervation criteria at last Holter recording as a time‐dependent covariate was associated with decreased hazard of mortality and/or retransplantation (HR: 0.2, 95% CI 0.04–1.0, p = 0.05). In conclusion, a majority of pediatric HTx recipients demonstrate evidence of reinnervation that is associated with functional outcomes. Studies to assess graft reinnervation as a marker of long‐term prognosis are warranted.     

Exercise Performance of Chronic Heart Failure Patients in the Early Period of Support by an Axial‐Flow Left Ventricular Assist Device as Destination Therapy

Axial‐flow left ventricular assist devices (LVADs) are increasingly used as destination therapy in end‐stage chronic heart failure (CHF), as they improve survival and quality of life. Their effect on exercise tolerance in the early phase after implantation is still unclear. The aim of this study was to evaluate the effect of LVADs on the exercise capacity of a group of CHF patients within 2 months after initiation of circulatory support. Cardiopulmonary exercise test data were collected for 26 consecutive LVAD‐implanted CHF patients within 2 months of initiation of assistance; the reference group consisted of 30 CHF patients not supported by LVAD who were evaluated after an episode of acute heart failure. Both LVAD and reference groups showed poor physical performance; LVAD patients achieved lower workload (LVAD: 36.3 ± 9.0 W, reference: 56.6 ± 18.2 W, P < 0.001) but reached a similar peak oxygen uptake (peak VO₂; LVAD: 12.5 ± 3.0 mL/kg/min, reference: 13.6 ± 2.9 mL/kg/min, P = ns) and similar percentages of predicted peak VO₂ (LVAD: 48.8 ± 13.9%, reference: 54.2 ± 15.3%, P = ns). While the values of the O₂ uptake efficiency slope were 12% poorer in LVAD patients than in reference patients (1124.2 ± 226.3 vs. 1280.2 ± 391.1; P = ns), the kinetics of VO₂ recovery after exercise were slightly better in LVAD patients (LVAD: 212.5 ± 62.5, reference: 261.1 ± 80.2 sec, P < 0.05). In the first 2 months after initiation of circulatory support, axial‐flow LVAD patients are able to sustain a low‐intensity workload; though some cardiopulmonary exercise test parameters suggest persistence of a marked physical deconditioning, their cardiorespiratory performance is similar to that of less compromised CHF patients, possibly due to positive hemodynamic effects beginning to be produced by the assist device.     

Interval training elicits higher enjoyment versus moderate exercise in persons with spinal cord injury

Background: High intensity interval training (HIIT) is a robust and time-efficient approach to improve multiple health indices including maximal oxygen uptake (VO₂max). Despite the intense nature of HIIT, data in untrained adults report greater enjoyment of HIIT versus continuous exercise (CEX). However, this has yet to be investigated in persons with spinal cord injury (SCI).

Objective: To examine differences in enjoyment in response to CEX and HIIT in persons with SCI.

Design: Repeated measures, within-subjects design.

Setting: University laboratory in San Diego, CA.

Participants: Nine habitually active men and women (age?=?33.3?±?10.5 years) with chronic SCI.

Intervention: Participants performed progressive arm ergometry to volitional exhaustion to determine VO₂peak. During subsequent sessions, they completed CEX, sprint interval training (SIT), or HIIT in randomized order.

Outcome Measures: Physical activity enjoyment (PACES), affect, rating of perceived exertion (RPE), VO₂, and blood lactate concentration (BLa) were measured.

Results: Despite a higher VO₂, RPE, and BLa consequent with HIIT and SIT (P?, PACES was significantly higher (P?=?0.03) in response to HIIT (107.4?±?13.4) and SIT (103.7?±?12.5) compared to CEX (81.6?±?25.4). Fifty-five percent of participants preferred HIIT and 45% preferred SIT, with none identifying CEX as their preferred exercise mode.

Conclusion: Compared to CEX, brief sessions of submaximal or supramaximal interval training elicit higher enjoyment despite higher metabolic strain. The long-term efficacy and feasibility of HIIT in this population should be explored considering that it is not viewed as more aversive than CEX.     

Cardiovascular response to peak voluntary exercise in males with cervical spinal cord injury

Context/Objective: Traumatic damage to the cervical spinal cord is usually associated with a disruption of the autonomic nervous system (ANS) and impaired cardiovascular control both during and following exercise. The magnitude of the cardiovascular dysfunction remains unclear. The aim of the current study was to compare cardiovascular responses to peak voluntary exercise in individuals with tetraplegia and able-bodied participants.

Design: A case-control study.

Subjects: Twenty males with cervical spinal cord injury (SCI) as the Tetra group and 27 able-bodied males as the Control group were included in the study.

Outcome Measures: Blood pressure (BP) response one minute after the peak exercise, peak heart rate (HR_peak), and peak oxygen consumption (VO_2peak) on an arm crank ergometer were measured. In the second part of the study, 17 individuals of the Control group completed the Tetra group's workload protocol with the same parameters recorded.

Results: There was no increase in BP in response to the exercise in the Tetra group. Able-bodied individuals exhibited significantly increased post-exercise systolic BP after the maximal graded exercise test (123±16%) and after completion of the Tetra group's workload protocol (114±11%) as compared to pre-exercise. The Tetra group VO_2peak was 59% and the HR_peak was 73% of the Control group VO_2peak and HR_peak, respectively.

Conclusions: BP did not increase following maximal arm crank exercise in males with a cervical SCI unlike the increases observed in the Control group. Some males in the Tetra group appeared to be at risk of severe hypotension following high intensity exercise, which can limit the ability to progressive increase and maintain high intensity exercise.     

Changes in Total Cardiac Output and Oxygen Extraction During Exercise in Patients Supported With an HVAD Left Ventricular Assist Device

Following implantation of a left ventricular assist device (LVAD), acceptable functional performance is now being achieved; however, peak VO₂ and peak work load (watts) remain considerably limited. Maximum physical capacity is essentially dependent on generated cardiac output (CO) and arteriovenous oxygen difference (avDO₂). We investigated the changes in CO and avDO₂ during exercise in LVAD patients with an HVAD pump (HeartWare Inc., Framingham, MA, USA). Approximately 6 weeks after implantation, 20 patients (100% male, 60.8 ± 7.3 years old, BMI 25.7 ± 3.3) underwent a six‐minute walk test (6MWT), a cardiopulmonary exercise test (CPET), and noninvasive hemodynamic measurement. The mean six‐minute walking distance (6MWD) was 403 m (68% of predicted), and mean peak VO₂ was 10.9 mL/kg/min (39% of predicted). Mean total CO improved from 3.8 L at rest to 7.0 L at maximum exercise. The mean avDO₂ increased from 7.4 mL/dL (44% of oxygen content) at rest to 13.2 mL/dL (75% of oxygen content) at maximum exercise. There was a significant increase in both total CO (P < 0.01) and avDO₂ (P < 0.05) between rest and sub‐maximum exercise. As exercise levels increased, however, no further significant changes were achieved. Long‐term studies, especially in combination with exercise programs, would be desirable in order to observe the development of these parameters.     

Compensatory Exercise Hyperventilation is Restored in the Morbidly Obese After Bariatric Surgery

Background Morbidly obese individuals may have poor compensatory hyperventilation during exercise. The objective was to examine pulmonary gas exchange and the compensatory hyperventilatory response during exercise pre- and post-weight reduction surgery in obese subjects. Methods Fifteen patients (age = 39 ± 8 years, body mass index = 47 ± 6 kg/m²), with an excess weight of 69 ± 17 kg, were recruited. Pulmonary function at rest was assessed and arterial-blood gases were sampled at rest and all levels of exercise pre- and 10 ± 3 weeks postsurgery. Results There was a loss of excess weight 21 ± 6 kg (p < 0.01). Waist and hip circumference decreased by 13 ± 9 and 8 ± 7 cm, respectively (p < 0.01). Prior to surgery, there was no compensatory hyperventilation between rest and peak exercise as arterial PCO₂ (PaCO₂) remained unchanged (37± 3 mm Hg). However, postsurgery, there was compensatory hyperventilation as PaCO₂ decreased to 33 ± 2 mm Hg at peak exercise (p < 0.01), with no change in peak oxygen consumption (VO_2peak in L/min). Multiple linear regression revealed that the restored ventilatory response to exercise was most strongly associated with the reduction in overall fat mass (adjusted r ² = 0.25; p = 0.03). Total weight loss of 21 kg induces adequate compensatory hyperventilation that begins to show at about 50% of VO_2peak, resulting in improved gas exchange at moderate to peak exercise intensities. Conclusion Improvement in compensatory hyperventilation is most closely related to loss in overall fat mass. G.S. Zavorsky is the recipient of the 2005 Baxter Corporation Award in Anesthesia from the Canadian Anesthesiologist’s Society. G.S. Zavorsky is also Research Scholar–Junior 1 from the Quebec Health Research Foundation (Fonds de la Recherche en Santé du Québec). N.V. Christou is a consultant for Ethicon Endo-Surgery and has stock ownership in Weight Loss Surgery.     

Assessment of Cardiorespiratory and Metabolic Responses in Women with Obesity After Surgically Induced Weight Loss: Results from a Pilot Study

Purpose

Bariatric surgery is effective in controlling severe obesity. However, studies investigating the impact of surgically induced weight loss on cardiorespiratory and metabolic responses during maximal effort are controversial. The aim of this study was to assess cardiorespiratory and metabolic responses in women with obesity after bariatric surgery.

Materials and Methods

We performed a secondary analysis on data from a pilot study with women with obesity submitted to bariatric surgery and who did not participate in a controlled physical training program. Anthropometry, pulmonary function (spirometry), and cardiorespiratory fitness (cardiopulmonary exercise testing [CPX]) were assessed before and after bariatric surgery.

Results

Thirty-four women were included (38.7 ± 9.6 years, body mass index = 44.1 ± 6.3 kg/m²). Postoperative assessment was conducted 9.4 ± 2.7 months after surgery. After surgery, we observed a reduction in all anthropometric measurements (mean loss of 28.6 kg, p < 0.001), and improvement in spirometry values (p < 0.001). Relative VO_2peak (mL/kg/min) increased slightly (Δ = 1.7; p = 0.06); however, absolute VO_2peak (L/min) reduced significantly (Δ =  − 0.398; p < 0.001). We also observed an increase of 1.3 min (p < 0.001) in CPX duration, a reduction of 11.3 bpm (p < 0.001) in resting heart rate, and a decrease of systolic (p = 0.02) and diastolic (p < 0.001) blood pressures at peak effort.

Conclusion

Surgically induced weight loss without exercise training improved cardiac reserve, ventilatory response, blood pressure, and resting heart rate. Cardiorespiratory fitness reflected by relative VO_2peak increased slightly, despite increased tolerance to CPX.

Graphical abstract

     

Effective training for patients with intermittent claudication

Objective. Current guidelines for treatment of intermittent claudication (IC) do not include a specific recommendation for the intensity of exercise therapy. Thus, the purpose of this study was to determine the relative effectiveness of high versus low intensity exercise for patients with IC, and further to study the effect of such training on blood flow to the legs during exercise. Design. The effect of eight weeks of supervised endurance training was examined in 16 patients with IC. The patients were randomly assigned to training at intensities corresponding to either 60% or 80% of their peak oxygen consumption (VO_2peak), respectively. Results. VO_2peak and time to exhaustion increased significantly (9% and 16%, respectively) more in the high intensity group (p<0.05). Blood flow to the legs did not change after training in any of the groups. Conclusion. High intensity training gave larger improvements in VO_2peak and time to exhaustion than low intensity training. As blood flow did not change after the exercise program, it is likely that the observed different increase of VO_2peak was due to changed mitochondrial oxidative capacity and/or skeletal muscle diffusive capacity.     

Health‐related quality of life,social support,and caregiver burden between six and 120 months after heart transplantation: a Spanish multicenter cross‐sectional study

A multicenter cross‐sectional study was conducted to determine the current heart transplant (HTx) outcomes in Spain. Clinical and functional status, health‐related quality of life (HRQoL), social support, and caregiver burden were analyzed in 303 adult transplant recipients (77.9% males) living with one functioning graft. Mean age at time of HTx (SD) was 56.4 (11.4) years, and the reason for transplantation in all patients was congestive heart failure. All patients had received a first heart transplant 6 (±1), 12 (±2), 36 (±6), 60 (±10), or 120 (±20) months previously. Participants completed the Kansas City Cardiomyopathy Questionnaire (KCCQ), the EQ‐5D, the Duke‐UNC Functional Social Support Questionnaire, and the Zarit Caregiver Burden Scale. Reasonable HRQoL, social support, and caregiver burden levels were found at all time points, although a slight decrease in HRQoL was recorded at 120 months (p ≤ 0.033). Multivariate regression analyses showed that complications, comorbidities, and hospitalizations were associated with HRQoL (EQ‐5D: 48.4% of explained variance, F_4,164 = 38.46, p < 0.001; KCCQ overall summary score: 45.0%, F_3,198 = 54.073, p < 0.001). Patient functional capabilities and complications affected caregiver burden (p < 0.05). In conclusion, HTx patients reported reasonable levels of HRQoL with low caregiver burden. Clinical variables related to these outcomes included functional status, complications, and number of admissions.     

Exercise training in haemodialysis patients: a systematic review and meta-analysis

Background We quantified baseline and observed change in peak VO₂, quality of life, cardiac function, strength and energy intake following exercise training in haemodialysis patients and optimal exercise delivery for producing greatest adherence, safety and patient improvements. Methods A systematic literature search was completed in August 2010 to identify randomized, controlled trials of exercise training studies in haemodialysis patients. A subsequent meta‐analysis was conducted and the search repeated in December 2010. Results Fifteen studies, yielding 565 patients were included. Baseline, peak VO₂ values were 70% of age‐predicted values, exercise intervention patients improved post‐training peak VO₂ to 88% predicted. Exercise training produced mean 26 ± 12% improvements in eight studies that reported peak VO₂, mean difference 5.22 mL O₂/kg per min (95% confidence interval 3.86, 6.59, P < 0.00001). Equivocal results for change in short‐form 36 health questionnaire scores were reported post‐training. Heart rate variability was improved after exercise training of normal to normal interval, mean difference 1634 milliseconds (95% confidence interval 8.3, 24.3, P < 0.0001). Significant improvements in lean body mass, quadriceps muscle area, knee extension, hip abduction and flexion strength were also reported (all P < 0.0001). Exercise training appears safe, with no deaths directly associated with exercise in 28 400 patient‐hours and no differences in withdrawal rates between exercise and control participants, P = 0.98. Exercise training for 6 months or more conveyed larger improvements in peak VO₂ than shorter programmes. Data indicate about 25% of patients were excluded from exercise training studies for medical reasons. Conclusion Exercise training is safe and imparts large improvements in peak VO₂, and heart rate variability.     

High-Intensity Training for 6 Months Safely,but Only Temporarily,Improves Exercise Capacity in Selected Solid Organ Transplant Recipients

BackgroundOrgan transplantation is a life-saving intervention that improves quality of life of patients with irreversible organ failure. Although exercise training immediately after transplantation has been suggested to be beneficial, such interventions remain rare in stable transplant recipients, whereas effects of high-intensity training (HIT) are even less frequently investigated. Moreover, sustainability of such interventions has not yet been reported. We investigated the effects of a 6-month, cycling-based HIT program on physical performance in long-term stable solid organ transplant (SOT) recipients, with follow-up evaluation after 6 months.MethodsForty-two adult, stable, and selected SOT recipients participated in a 6-month individualized home- and group-based HIT program. Exercise capacity (VO₂max), maximal power (Wmax), and body mass index were measured before, at the end, and 6 months after completion of the intervention.ResultsThe study comprised 12 heart, 7 lung, 8 liver, and 15 kidney recipients (mean age, 41.4 ± 11.1 years; median time posttransplant, 3.4 [1.7-8.0] years). For 6 months, VO₂max increased in the heart, lung, and kidney groups, Wmax increased in the heart group, and body mass index decreased in the liver group. Six months after the HIT program, the achieved gain in exercise capacity had disappeared in all groups.ConclusionDespite voluntary participation selection bias, our observations indicate that HIT is safe and may result in a beneficial effect on physical performance in selected, stable SOT recipients. However, there was no sustained beneficial effect once training stopped. Larger scale and longer term studies are still required to investigate longevity of improvement and overall beneficial effects on clinical outcomes.     

Relationship between Fat Oxidation and Lactate Threshold in Athletes and Obese Women and Men

The first aim of this study was to determine the exercise intensity that elicited the highest rate of fat oxidation in sedentary, obese subjects (OB; n=10 men, n=10 women) compared with endurance athletes (AT; n=10 men, n=10 women). The second aim was to investigate the relationship between VO₂ at the intensity eliciting the highest rate of fat oxidation and the corresponding VO₂ at the lactate threshold. Peak oxygen consumption (VO_2peak) was determined in 20 AT and 20 OB using an incremental exercise protocol on a cycle ergometer. Based on their VO_2peak values, subjects completed a protocol requiring them to exercise for 20 min at three different workloads (55, 65 and 75% VO_2peak), randomly assigned on two separate occasions. The oxidation rates of fat and carbohydrate were measured by indirect calorimetry. The highest rates of fat oxidation were at 75 % VO_2peak (AT), and at 65 % VO_2peak (OB). The rate of fat oxidation was significantly higher in AT (18.2 ± 6.1) compared with OB women (10.6 ± 4.5 kJ min^-1·kg^-1) (p < 0.01). There was no significant difference in the rate of fat oxidation for the men (AT 19.7 ± 8.1 vs. OB 17.6 ± 8.2 kJ min^-1·kg^-1). AT reached LT at a significantly (p < 0.01) higher exercise intensity expressed in VO_2peak than obese subjects (AT women 76.4 ± 0.1, men 77.3 ± 0.1 vs. OB women, 49.7 ± 0.1, men 49.5 ± 0.1% VO_2peak). A significant correlation was found between VO₂ at LT and VO₂ (L·min^-1) eliciting the maximal rate of fat oxidation in athletes (women; r = 0.67; p = 0.03; men: r = 0.75; p = 0.01) but not in the obese. In summary, we observed higher rates of fat oxidation at higher relative work rates in AT compared with OB. A significant correlation was found between LT and the exercise intensity eliciting a high rate of fat oxidation in AT (r=0.89; p < 0.01) but not in OB. Cardiorespiratory fitness, defined as VO_2peak, seems to be important in defining the relationship between a high rate of fat oxidation and LT.

Key Points

• Within the tested intensities of 55, 65 and 75% VO_2peak athletes reached higher rates of fat oxidation at higher relative work rates compared with obese subjects.
• We found in obese women and men the intensity of the highest rate of fat oxidation at 65% VO_2peak.
• Between the lactate threshold and the intensity eliciting a high rate of fat oxidation a significant correlation was found in athletes but not in obese subjects.

Key words: Exercise intensity, substrate utilization, obesity, lactate threshold     

Effect of everolimus vs calcineurin inhibitors on quality of life in heart transplant recipients during a 3‐year follow‐up: Results of a randomized controlled trial (SCHEDULE)

The Sc andinavian he art transplant everolimus d e novo st u dy with ear l y calcineurin inhibitors avoidanc e (SCHEDULE) trial was a 12 month, randomized, open‐label, parallel‐group trial that compared everolimus (EVR; n=56) to conventional CsA (n=59) immunosuppression. Previously, we reported that EVR outperformed CsA in improving renal function and coronary artery vasculopathy, despite a higher rejection rate with EVR. This study aimed to compare the effects of these treatments on quality of life (QoL). Within five post‐operative days, patients (mean age 50±13 years, 27% women) were randomized to EVR or a standard CsA dosage (CsA group). This study assessed quality of life (QoL), based on the Short Form‐36, EuroQol‐5D, and Beck Depression Inventory (BDI). Assessments were performed pre‐HTx and 12 and 36 months post‐HTx. At 12 and 36 months, the groups showed similar improvements in Short Form‐36 measures (at pre‐HTx, 12 and 36 months the values were as follows: Physical component summary: EVR: 31.5±110.9, 49.1±9.7, and 47.9±10.6; P<.01; CsA: 32.5±8.2, 48.4±8.5, and 46.5±11.5; P<.01; mental component summary: EVR: 46.0±12.0, 51.7±11.9, and 52.1±13.0; P<.01; CsA: 38.2±12.5, 53.4±7.1, and 54.3±13.0; P<.01); similar decrease in mean BDI (EVR: 10.9±10.2, 5.4±4.7, and 8.1±9.0; P<.01; CsA: 11.8±7.1, 6.3±5.4, and 6.2±6.5; P<.01); and similar Euro Qol‐improvements. Thus, in this small‐sized study, EVR‐based and conventional CsA immunosuppressive strategies produced similar QoL improvements.     

Net Fluxes Over Working Thigh of Hormones,Growth Factors and Biomarkers of Bone Metabolism During Short Lasting Dynamic Exercise

The purpose of this study was to evaluate the responses of hormones, growth factors, and biomarkers involved in bone and muscle metabolism during exercise and in recovery. One leg knee-extension exercise and concomitant sampling from the artery and vein were performed. In 12 healthy individuals (6 men and 6 women; age 21–36 years) blood was drawn from the femoral artery and vein at rest, after 10 minutes warm-up, after 15 minutes work at 61% of peak one leg VO₂, and after 5 minutes work at peak one leg VO₂, as well as 5, 30, and 60 minutes in recovery. Blood flow in the femoral vein was measured using the thermodilution technique. Arteriovenous differences were measured over working thigh for growth hormone (GH), insulin-like growth factor I (IGF-I), insulin-like growth factor binding protein 3 (IGF BP3), parathyroid hormone (PTH) and bone biomarkers, i.e., the carboxyterminal propeptide of type I procollagen (PICP), the carboxyterminal cross-linked telopeptide of type I collagen (ICTP), osteocalcin, and bone-specific alkaline phosphatase (b-ALP). There was an uptake of GH (3.1 ± 1.2 mU · min⁻¹, P < 0.001; mean ± SE) over thigh during exercise and a release of IGF-I at the end of exercise (60 ± 36 μg · min⁻¹; P < 0.01). PICP was also released after the maximal exercise (23 ± 12 μg · min⁻¹; P < 0.01) as well as ICTP (0.5 ± 0.3 μg · min⁻¹; P < 0.05) and b-ALP (0.2 ± 0.1 μkat · min⁻¹; P < 0.05). Osteocalcin, IGF BP3, and PTH revealed no clearcut pattern. In the present study, exercise induces endocrine changes which point to anabolic effects on muscle and bone tissue. Received: 12 February 1996 / Accepted: 6 June 1996     

The Effects of Intermittent Exercise on Physiological Outcomes in an Obese Population: Continuous Versus Interval Walking

This study compared the effects of 12 weeks of caloric restriction and interval exercise (INT) and caloric restriction and continuous aerobic exercise (CON) on physiological outcomes in an obese population. Forty-four individuals (BMI ≥ 30 kg·m^-2) were randomised into the INT or CON group. Participant withdrawal resulted in 12 and 14 participants in the INT and CON groups, respectively. All participants were on a strict monitored diet. Exercise involved two 15-min bouts of walking performed on five days per week. Interval exercise consisted of a 2:1 min ratio of low-intensity (40-45% VO_2peak) and high- intensity (70-75% VO_2peak) exercise, while the CON group exercised between 50-55% VO_2peak. Exercise duration and average intensity (%VO_2peak) were similar between groups. There were no significant differences (p > 0.05) between the two groups for any variable assessed apart from very low density lipoprotein (VLDL-C), which significantly decreased over time in the INT group only (p < 0.05, d = 1.03). Caloric restriction and interval exercise compared to caloric restriction and continuous aerobic exercise resulted in similar outcome measures apart from VLDL-C levels, which significantly improved in the INT group only.

Key points

• Twelve weeks of interval exercise and caloric restriction resulted in significant improvement in very low density lipoprotein cholesterol in an obese population, as compared to continuous aerobic exercise and caloric restriction.
• Twelve weeks of either interval exercise or continuous exercise resulted in similar improvements in aerobic fitness in an obese population.

Key words: Interval training, body fat, fitness, metabolism     

Clinical utility of the oxygen uptake efficiency slope in cystic fibrosis patients

BackgroundThe present study investigated the validity and the reliability of the oxygen uptake efficiency slope (OUES) as a determinant of exercise tolerance in adults with cystic fibrosis (CF).Methods31 CF patients and 34 healthy controls performed a maximal incremental cycle test with respiratory gas-exchange measurements. OUES was calculated from data taken from different percentages of the entire exercise duration, including 80% (OUES₈₀) and 100% (OUES₁₀₀). Peak oxygen uptake (VO_2peak) and gas exchange threshold (GET) were also determined. The agreement between submaximal parameters and VO_2peak was assessed using Bland Altman plots. Test retest reliability was evaluated in CF patients using absolute (SEM) and relative indices (ICC).ResultsOn the contrary to the GET, which was undetectable in 16% of the CF patients, the OUES was easily determined in all patients. Among all the submaximal variables, OUES₈₀ had the best reliability (ICC = 0.94, SEM = 7.3%) and agreement with VO_2peak (r² = 0.83, P < 0.01; limits of agreement: ± 365 mL min^− 1) and did not differ from OUES₁₀₀.ConclusionsOUES₈₀ is a reliable and more useful submaximal parameter than the GET and may find use in the interpretation of exercise studies in CF patients who are unable to perform maximal exercise.