Ioannis Nasis

Effect of Pulmonary Rehabilitation on Peripheral Muscle Fiber Remodeling in Patients With COPD in GOLD Stages II to IV

BACKGROUND In most patients with COPD, rehabilitative exercise training partially reverses the morphologic and structural abnormalities of peripheral muscle fibers. However, whether the degree of improvement in muscle fiber morphology and typology with exercise training varies depending on disease severity remains unknown. METHODS Forty-six clinically stable patients with COPD classified by GOLD (Global Initiative for Obstructive Lung Disease) as stage II (n = 14), III (n = 18), and IV (n = 14) completed a 10-week comprehensive pulmonary rehabilitation program consisting of high-intensity exercise three times weekly. RESULTS At baseline, muscle fiber mean cross-sectional area and capillary density did not significantly differ between patients with COPD and healthy control subjects, whereas muscle fiber type I and II proportion was respectively lower (P < .001) and higher (P < .002) in patients with GOLD stage IV compared with healthy subjects and patients with GOLD stages II and III. Exercise training improved, to a comparable degree, functional capacity and the St. George Respiratory Questionnaire health-related quality of life score across all three GOLD stages. Vastus lateralis muscle fiber mean cross-sectional area was increased (P < .001) in all patient groups (stage II: from 4,507 ± 280 μm² to 5,091 ± 271 μm² [14% ± 3%]; stage III: from 3,753 ± 258 μm² to 4,212 ± 268 μm² [14% ± 3%]; stage IV: from 3,961 ± 266 μm² to 4,551 ± 262 μm² [17% ± 5%]), whereas all groups exhibited a comparable reduction (P < .001) in type IIb fiber proportion (stage II: by 6% ± 2%; stage III: by 6% ± 1%; stage IV: by 7% ± 1%) and an increase (P < .001) in capillary to fiber ratio (stage II: from 1.48 ± 0.10 to 1.81 ± 0.10 [23% ± 5%]; stage III: from 1.29 ± 0.06 to 1.56 ± 0.09 [21% ± 5%]; stage IV: from 1.43 ± 0.10 to 1.71 ± 0.13 [18 ± 3%]). The magnitude of changes in the aforementioned variables did not differ across GOLD stages. CONCLUSIONS Functional capacity and morphologic and typologic adaptations to rehabilitation in peripheral muscle fibers were similar across GOLD stages II to IV. Pulmonary rehabilitation should be implemented in patients at all COPD stages.

Cardiovascular effects of high-intensity interval aerobic training combined with strength exercise in patients with chronic heart failure. A randomized phase III clinical trial

BACKGROUND The aim of this work was to evaluate the effect of high-intensity interval exercise (i.e., 30s at 100% of max workload, followed by 30s at rest, 45 min 3 days/week working-out schedule for 12 weeks) on left ventricular function and aortic elastic properties among chronic heart failure (CHF) patients. METHODS This study is a phase III clinical trial. Of the 100 consecutive CHF patients (NYHA classes II-IV, ejection fraction<50%) that were randomly allocated, 72 completed the study (exercise training group, n=33, 63 ± 9 years, 88% men, and control group, n=39, 56 ± 11 years, 82% men). All patients underwent cardiopulmonary stress test, non-invasive high-fidelity tonometry of the radial artery, pulse wave velocity measurement using a SphygmoCor device and echocardiography before and after the completion of the training program. RESULTS Both groups reported similar medical characteristics and physical activity status. General mixed effects models revealed that the intervention group reduced pulse wave velocity by 9% (p=0.05); Emv/Vp by 14% (p=0.06); E to A ratio by 24% (p=0.004), E to Emv ratio by 8% (p=0.05), MLHFQ score by 66% (p=0.003) and the depression score by 19% (p=0.5); increased augmentation index by 29%; VTI by 4% (p=0.05), 6-minute-walk distance up to 13% (p=0.05), peak oxygen uptake by 28% (p=0.001) and peak power by 25% (p=0.005). There were no significant changes in the control group. CONCLUSION Interval high-intensity aerobic training, combined with strength exercise, seems to benefit aortic dilatation capacity and augmented systolic pressure in parallel with improvement in left ventricular diastolic function and quality of life.

Intensity of daily physical activity is associated with central hemodynamic and leg muscle oxygen availability in COPD

In chronic obstructive pulmonary disease (COPD), daily physical activity is reported to be adversely associated with the magnitude of exercise-induced dynamic hyperinflation and peripheral muscle weakness. There is limited evidence whether central hemodynamic, oxygen transport, and peripheral muscle oxygenation capacities also contribute to reduced daily physical activity. Nineteen patients with COPD (FEV1, 48 ± 14% predicted) underwent a treadmill walking test at a speed corresponding to the individual patients mean walking intensity, captured by a triaxial accelerometer during a preceding 7-day period. During the indoor treadmill test, the individual patient mean walking intensity (range, 1.5 to 2.3 m/s2) was significantly correlated with changes from baseline in cardiac output recorded by impedance cardiography (range, 1.2 to 4.2 L/min; r = 0.73), systemic vascular conductance (range, 7.9 to 33.7 ml·min(-1)·mmHg(-1); r = 0.77), systemic oxygen delivery estimated from cardiac output and arterial pulse-oxymetry saturation (range, 0.15 to 0.99 L/min; r = 0.70), arterio-venous oxygen content difference calculated from oxygen uptake and cardiac output (range, 3.7 to 11.8 mlO2/100 ml; r = -0.73), and quadriceps muscle fractional oxygen saturation assessed by near-infrared spectrometry (range, -6 to 23%; r = 0.77). In addition, mean walking intensity significantly correlated with the quadriceps muscle force adjusted for body weight (range, 0.28 to 0.60; r = 0.74) and the ratio of minute ventilation over maximal voluntary ventilation (range, 38 to 89%, r = -0.58). In COPD, in addition to ventilatory limitations and peripheral muscle weakness, intensity of daily physical activity is associated with both central hemodynamic and peripheral muscle oxygenation capacities regulating the adequacy of matching peripheral muscle oxygen availability by systemic oxygen transport.

Effects of interval-load versus constant-load training on the BODE index in COPD patients

The BODE index is frequently used to assess functional capacity in patients with COPD. The aim of this study was to investigate the effectiveness of interval-load training (ILT) to improve the BODE index in comparison to the commonly implemented constant-load training (CLT). Forty-two patients with COPD [FEV(1): (mean+/-SEM) 42+/-3% predicted] were randomly allocated to either ILT (n=21) or CLT (n=21). The training program consisted of cycling exercise 3 days/week for 10 weeks. Patients assigned to ILT exercised at a mean intensity of 126+/-4% of baseline peak work rate (Wpeak) with 30-s work periods alternated with 30-s rest periods for 45 min per day, whereas patients allocated to CLT exercised at a mean intensity of 76+/-5% of baseline Wpeak for 30 min per day. The BODE index and its components: body mass index, FEV(1), MMRC dyspnea score and the 6-min walk test (6-MWT) as well as cycling Wpeak were assessed before and after both exercise training regimes. Both ILT and CLT significantly (p<0.001) decreased the BODE index (from 4.8+/-0.5 to 4.0+/-0.5 units and from 4.4+/-0.5 to 3.8+/-0.5 units, respectively). In addition, both ILT and CLT significantly decreased the MMRC dyspnea score by 0.4+/-0.1 units and increased the 6-MWT (by 52+/-16 and 44+/-12 m, respectively) as well as cycling Wpeak (by 14+/-2 and 10+/-2W, respectively). The magnitude of these changes was not significantly different between ILT and CLT. Consequently, ILT is equally effective to CLT in terms of improving the BODE index in patients with COPD and as such it may constitute an alternative rehabilitative modality in COPD.

On- and off-exercise kinetics of cardiac output in response to cycling and walking in COPD patients with GOLD Stages I-IV.

Exercise-induced dynamic hyperinflation and large intrathoracic pressure swings may compromise the normal increase in cardiac output (Q) in Chronic Obstructive Pulmonary Disease (COPD). Therefore, it is anticipated that the greater the disease severity, the greater would be the impairment in cardiac output during exercise. Eighty COPD patients (20 at each GOLD Stage) and 10 healthy age-matched individuals undertook a constant-load test on a cycle-ergometer (75% WR(peak)) and a 6min walking test (6MWT). Cardiac output was measured by bioimpedance (PhysioFlow, Enduro) to determine the mean response time at the onset of exercise (MRTon) and during recovery (MRToff). Whilst cardiac output mean response time was not different between the two exercise protocols, MRT responses during cycling were slower in GOLD Stages III and IV compared to Stages I and II (MRTon: Stage I: 45±2, Stage II: 65±3, Stage III: 90±3, Stage IV: 106±3s; MRToff: Stage I: 42±2, Stage II: 68±3, Stage III: 87±3, Stage IV: 104±3s, respectively). In conclusion, the more advanced the disease severity the more impaired is the hemodynamic response to constant-load exercise and the 6MWT, possibly reflecting greater cardiovascular impairment and/or greater physical deconditioning.

Limitation in tidal volume expansion partially determines the intensity of physical activity in COPD

In patients with chronic obstructive pulmonary disease (COPD), reduced levels of daily physical activity are associated with the degree of impairment in lung, peripheral muscle, and central hemodynamic function. There is, however, limited evidence as to whether limitations in tidal volume expansion also, importantly, determine daily physical activity levels in COPD. Eighteen consecutive patients with COPD [9 active (forced expiratory volume in 1 s, FEV1: 1.59 ± 0.64 l) with an average daily movement intensity >1.88 m/s(2) and 9 less active patients (FEV1: 1.16 ± 0.41 l) with an average intensity <1.88 m/s(2)] underwent a 4-min treadmill test at a constant speed corresponding to each individual patients average movement intensity, captured by a triaxial accelerometer during a preceding 7-day period. When chest wall volumes, captured by optoelectronic plethysmography, were expressed relative to comparable levels of minute ventilation (ranging between 14.5 ± 4.3 to 33.5 ± 4.4 l/min), active patients differed from the less active ones in terms of the lower increase in end-expiratory chest wall volume (by 0.15 ± 0.17 vs. 0.45 ± 0.21 l), the greater expansion in tidal volume (by 1.76 ± 0.58 vs. 1.36 ± 0.24 l), and the larger inspiratory reserve chest wall volume (IRVcw: by 0.81 ± 0.25 vs. 0.39 ± 0.27 l). IRVcw (r(2) = 0.420), expiratory flow (r(2) change = 0.174), and Borg dyspnea score (r(2) change = 0.123) emerged as the best contributors, accounting for 71.7% of the explained variance in daily movement intensity. Patients with COPD exhibiting greater ability to expand tidal volume and to maintain adequate inspiratory reserve volume tend to be more physically active. Thus interventions aiming at mitigating restrictions on operational chest wall volumes are expected to enhance daily physical activity levels in COPD.

Hemodynamic effects of high intensity interval training in COPD patients exhibiting exercise-induced dynamic hyperinflation.

Dynamic hyperinflation (DH) has a significant adverse effect on cardiovascular function during exercise in COPD patients. COPD patients with (n = 25) and without (n = 11) exercise-induced DH undertook an incremental (IET) and a constant-load exercise test (CLET) sustained at 75% peak work (WRpeak) prior to and following an interval cycling exercise training regime (set at 100% WRpeak with 30-s work/30-s rest intervals) lasting for 12 weeks. Cardiac output (Q) was assessed by cardio-bio-impedance (PhysioFlow, enduro, PF-O7) to determine Q mean response time (QMRT) at onset (QMRT(ON)) and offset (QMRT(OFF)) of CLET. Post-rehabilitation only those patients exhibiting exercise-induced DH demonstrated significant reductions in QMRT(ON) (from 82.2 ± 4.3 to 61.7 ± 4.2 s) and QMRT(OFF) (from 80.5 ± 3.8 to 57.2 ± 4.9 s ). These post-rehabilitation adaptations were associated with improvements in inspiratory capacity, thereby suggesting that mitigation of the degree of exercise-induced DH improves central hemodynamic responses in COPD patients.

Activity monitoring reflects cardiovascular and metabolic variations in COPD patients across GOLD stages II to IV.

We investigated whether activity monitoring reliably reflects variations in oxygen transport and utilization during walking in COPD patients. Forty-two patients (14 in each GOLD stage II, III and IV) performed an incremental treadmill protocol to the limit of tolerance. Breath-by-breath gas exchange, central hemodynamic variables and activity monitoring were simultaneously recorded. Physiological variables and accelerometer outputs rose linearly with walking speeds. Strong correlations (r[interquartile range, IQR]) were found between treadmill walking intensity (WI: range 0.8-2.0 ms(-2)) and oxygen consumption (0.95 [IQR 0.87-0.97]), (range 7.6-15.5 ml kg(-1)min(-1)); minute ventilation (0.95 [IQR 0.86-0.98]), (range 20-37 l min(-1)); cardiac output (0.89 [IQR 0.73-0.94]), (range 6.8-11.5 l min(-1)) and arteriovenous oxygen concentration difference (0.84 [IQR 0.76-0.90]), (range 7.7-12.1 ml O2100 ml(-1)). Correlations between WI and gas exchange or central hemodynamic parameters were not different across GOLD stages. In conclusion, central hemodynamic, respiratory and muscle metabolic variations during incremental treadmill exercise are tightly associated to changes in walking intensity as recorded by accelerometry across GOLD stages II to IV. Interestingly, the magnitude of these associations is not different across GOLD stages.

Interval training induces clinically meaningful effects in daily activity levels in COPD

Mounting evidence suggests that daily activity levels (DAL) in patients with chronic obstructive pulmonary disease (COPD) are markedly low compared with healthy age-matched individuals and are associated with poorer health status and prognosis [1]. COPD severity negatively impacts on DAL since patients with low DAL experience greater ventilatory, central haemodynamic and peripheral muscle oxygenation constraints during activities of daily living when compared with more physically active counterparts [2, 3]. Although exercise training as part of pulmonary rehabilitation has shown to mitigate the aforementioned physiological constraints [4], there is no evidence of clinically meaningful improvements in DAL following pulmonary rehabilitation [5] as manifested by a mean increase of at least 1000 steps·day−1 [6]. This has been attributed to methodological shortfalls, such as lack of adequately controlled studies, small sample size, short duration of pulmonary rehabilitation programmes, application of activity monitors non-validated for COPD patients [5] and insufficient exercise intensities to induce true physiological training effects. Interval exercise training has been shown to allow application of intense loads to peripheral muscles that induce substantial physiological effects manifested by mitigation of respiratory and central haemodynamic limitations and partial restoration of peripheral muscle dysfunction in patients with diverse COPD severity [7, 8]. In this context, it is reasoned that application of this training modality would allow transfer of the aforementioned physiological benefits into clinically meaningful improvements in DAL [2, 3]. Accordingly, the purpose of this randomised controlled study was to investigate the effect of a 12-week high-intensity interval exercise training programme in DAL in addition to usual care in patients with COPD. 12 weeks of interval training induces clinically meaningful effects in amount and intensity of daily activities in COPD http://ow.ly/rZXI3002awp