Inspiratory muscle training improves cycling time-trial performance and anaerobic work capacity but not critical power

We examined whether inspiratory muscle training (IMT) improved cycling time-trial performance and changed the relationship between limit work (W _lim) and limit time (T _lim), which is described by the parameters critical power (CP) and anaerobic work capacity (AWC). Eighteen male cyclists were assigned to either a pressure-threshold IMT or sham hypoxic-training placebo (PLC) group. Prior to and following a 6 week intervention subjects completed a 25-km cycling time-trial and three constant-power tests to establish the W _lim–T _lim relationship. Constant-power tests were prescribed to elicit exercise intolerance within 3–10 (Ex1), 10–20 (Ex2), and 20–30 (Ex3) min. Maximal inspiratory mouth pressure increased by (mean ± SD) 17.1 ± 12.2% following IMT (P < 0.01) and was accompanied by a 2.66 ± 2.51% improvement in 25-km time-trial performance (P < 0.05); there were no changes following PLC. Constant-power cycling endurance was unchanged following PLC, as was CP (pre vs. post: 249 ± 32 vs. 250 ± 32 W) and AWC (30.7 ± 12.7 vs. 30.1 ± 12.5 kJ). Following IMT Ex1 and Ex3 cycling endurance improved by 18.3 ± 15.1 and 15.3 ± 19.1% (P < 0.05), respectively, CP was unchanged (264 ± 62 vs. 263 ± 61 W), but AWC increased from 24.8 ± 5.6 to 29.0 ± 8.4 kJ (P < 0.05). In conclusion, these data provide novel evidence that improvements in constant-power and cycling time-trial performance following IMT in cyclists may be explained, in part, by an increase in AWC.     

Improvement after lung volume reduction surgery: a role for inspiratory muscle adaptation

In severe emphysema, lung volume reduction surgery (LVRS) can improve lung function and exercise tolerance. The maximal changes of forced expiratory volume in 1s (FEV(1)) and lung volume occur early after surgery, whereas maximal improvement of exercise tolerance occurs later. We tested the hypothesis that secondary adaptation of inspiratory muscles could explain this delayed clinical improvement. In that purpose, we evaluated nine consecutive patients before LVRS and up to 9 months post-operatively. Six weeks after LVRS, we observed an increase in FEV(1) and 6 min walk distance (6MWD). The gain in sniff nasal inspiratory pressure (SNIP) was inversely proportional to lung volume loss. Values of FEV(1) and lung volume were maintained throughout follow-up whereas SNIP values significantly increased from 6 weeks to 6 months post-LVRS. In the meantime, we observed an increase in 6MWD correlated with the SNIP increase. This suggests that in patients undergoing LVRS, early improvement of SNIP is proportional to decrease in lung volume whereas the further delayed improvement may be due, at least in part, to adaptation of the inspiratory muscles.     

Predictors of nocturnal oxyhemoglobin desaturation in COPD

It would be useful to detect predictors of marked nocturnal oxyhemoglobin desaturation (NOD) among COPD patients, who do not have respiratory failure when awake and sleep apnea (SA). Stable COPD patients with awake Pa(O2) ≥ 60 mmHg and Pa(CO2) ≤ 45 mmHg underwent cardio-respiratory polysomnography to exclude SA and to assess NOD. The patients that spent more than 30% of night time with Sp(O2) < 90%, were defined desaturators (D), and the others non desaturators (ND). Pulmonary function testing was performed to determine lung volumes, maximal flow rates, lung diffusion capacity for carbon monoxide and maximal inspiratory and expiratory pressure (P(Imax) and P(Emax)). Negative expiratory pressure test was performed to assess tidal expiratory flow limitation. Supine pharyngometry was performed to determine upper airway size, shuttle walking test to assess exercise desaturation. Twenty-one patients were included in the study (18 male, age 66.0±7.2 years, Body Mass Index 25.9±4.4 kg/m(2), FEV(1) 47.2±16.4% pred., Pa(O2) 74.7±6.9 mmHg, Pa(CO2) 40.3±3.4 mmHg): 10 were D and 11 ND. Significant differences between the two groups were found in diurnal Pa(CO2) (D: 42.4±3.0 vs. ND: 38.3±2.6mmHg; p<0.01), diurnal Sp(O2) (D: 94.0±1.5 vs. ND: 95.9±0.9%; p<0.01), inspiratory capacity (IC) (D: 69.6±11.9 vs. ND: 87.0±17.7% pred.; p<0.05), and oro-pharyngeal junction area (OPJ) (D: 0.8±0.2 vs. ND: 1.2±0.3 cm(2); p<0.01). Among parameters related to marked NOD at the univariate analysis, [Formula: see text] and OPJ remained as independent predictors after stepwise multiple regression analysis. These findings indicate that previously unrecognized factors such as smaller upper airway caliber and lung dynamic hyperinflation are associated with marked NOD in stable COPD patients without daytime respiratory failure and SA.     

Cardiopulmonary fitness assessment on maximal and submaximal exercise testing in patients with Fabry disease

The cardiopulmonary exercise test (CPET) is a valuable tool to assess a patient's aerobic fitness and cardiac function, including the response to stress. There have been few studies using CPET to evaluate cardiopulmonary exercise capacity in patients with Fabry disease. We performed a retrospective chart review of patients with Fabry disease from 2001 to 2016, compared to age, gender, and size‐matched normal controls. A total of 18 patients were evaluated using the Bruce protocol (treadmill) and 11 patients were evaluated with the ramp protocol (cycle ergometer). The Fabry group demonstrated significantly lower heart rate at peak exercise (151.2 ± 22.5 vs. 178.6 ± 16.2, p < .05), max indexed VO₂ (23.7 ± 7 vs. 33.9 ± 8.4, p < .05), and peak index oxygen pulse (12.1 ± 3 vs. 15.2 ± 4.2, p < .05). When the groups were further separated into treadmill or cycle ergometry testing only, there remained statistically significant differences in peak indexed oxygen pulse, heart rate at peak exercise, and max indexed VO₂. There was a statistically significant difference between the Fabry patients evaluated by treadmill testing for systolic blood pressure at peak exercise that was not seen in the cycle ergometry group. Additionally, when looking at the patients who had concurrent cardiac MRI (cMRI) with their CPET, there was a positive correlation with max indexed VO₂ and right ventricular end‐diastolic volume (r = .55, p = .007) and end‐systolic volume (r = .59, p = .007). Patients with Fabry disease have impaired cardiopulmonary exercise capacity as measured by CPET. Additionally, in patients with Fabry disease there is a positive correlation with functional capacity and right ventricular volumes on cMRI.     

Supplemental oxygen and muscle metabolism in mitochondrial myopathy patients

Patients with mitochondrial myopathy (MM) have a reduced capacity to perform exercise due to a reduced oxidative capacity. We undertook this study to determine whether skeletal muscle metabolism could be improved with oxygen therapy in patients with MM. Six patients with MM and six controls, matched for age, gender and physical activity, underwent ³¹P-magnetic resonance spectroscopy (³¹P-MRS) examination. ³¹P-MR spectra were collected at rest and in series during exercise and recovery whilst breathing normoxic (0.21 O₂) or hyperoxic (1.0 O₂) air. At rest, MM showed an elevated [ADP] (18 ± 3 μmol/l) and pH (7.03 ± 0.01) in comparison to the control group (12 ± 1 μmol/l, 7.01 ± 0.01) (P < 0.05) consistent with mitochondrial dysfunction. Oxygen supplementation did not change resting metabolites in either MM or the control group (P > 0.05). Inferred maximal ATP synthesis rate improved by 33% with oxygen in MM (21 ± 3 vs. 28 ± 5 mmol/(l min), P < 0.05) but only improved by 5% in controls (40 ± 3 vs. 42 ± 3 mmol/(l min), P > 0.05). We conclude that oxygen therapy is associated with significant improvements in muscle metabolism in patients with MM. These data suggest that patients with MM could benefit from therapies which improve the provision of oxygen.     

Effect of specific inspiratory muscle warm-up on intense intermittent run to exhaustion

The effects of inspiratory muscle (IM) warm-up on the maximum dynamic IM function and the maximum repetitions of 20-m shuttle run (Ex) in the Yo-Yo intermittent recovery test were examined. Ten men were recruited to perform identical IM function test and exercise test in three different trials randomly. The control trial was without IM warm-up while the placebo and experimental trials were with IM warm-up by performing two sets of 30 breaths with inspiratory pressure-threshold load equivalent to 15% (IMW_P) and 40% (IMW) maximum inspiratory mouth pressure, respectively. In IMW, maximum dynamic IM functions including the maximal inspiratory pressure at zero flow (P ₀) and maximal rate of P ₀ development (MRPD) were increased compared with control values (P<0.05). The Ex was also augmented [mean (SD)] [19.5% (12.6)] while the slope of the linear relationship of the increase in rating of perceived breathlessness for every 4th exercise interval (RPB/4i) was reduced (P<0.05). In IMW_P, although increase in Ex and reduction in RPB/4i were occurred concomitantly in some subjects, the differences in Ex, RPB/4i and dynamic IM functions between control and IMW_P trials were not statistically significant. For the changes (Δ) in parameters in IMW and IMW_P (n=20), negative correlations were found between Δ RPB/4i and Δ Ex (r=−0.92), ΔP ₀ and Δ RPB/4i (r=−0.48), and Δ MRPD and Δ RPB/4i (r=−0.54). Such findings suggested that the specific IM warm-up in IMW may entail reduction in breathlessness sensation, partly attributable to the enhancement of dynamic IM functions, in subsequent exhaustive intermittent run and, in turn, improve the exercise tolerance.     

How can autoantibodies predict the long-term outcome of patients with interstitial lung disease? Results from a retrospective cohort study

Objectives

This study aimed to investigate whether positive serum autoantibodies (AAbs) have any impact on survival and time evolution of radiological findings and pulmonary function indices in patients with interstitial lung disease (ILD).

Pulmonary adaptations to swim and inspiratory muscle training

Because the anomalous respiratory characteristics of competitive swimmers have been suggested to be due to inspiratory muscle work, the respiratory muscle and pulmonary function of 30 competitively trained swimmers was assessed at the beginning and end of an intensive 12-week swim training (ST) program. Swimmers (n = 10) combined ST with either inspiratory muscle training (IMT) set at 80% sustained maximal inspiratory pressure (SMIP) with progressively increased work-rest ratios until task failure for 3-days per week (ST + IMT) or ST with sham-IMT (ST + SHAM-IMT, n = 10), or acted as controls (ST only, ST, n = 10). Measures of respiratory and pulmonary function were assessed at the beginning and end of the 12 week study period. There were no significant differences (P > 0.05) in respiratory and pulmonary function between groups (ST + IMT, ST + SHAM-IMT and ST) at baseline and at the end of the 12 week study period. However, within all groups significant increases (P < 0.05) were observed in a number of respiratory and pulmonary function variables at the end of the 12 week study, such as maximal inspiratory and expiratory pressure, inspiratory power output, forced vital capacity, forced expiratory and inspiratory volume in 1-s, total lung capacity and diffusion capacity of the lung. This study has demonstrated that there are no appreciable differences in terms of respiratory changes between elite swimmers undergoing a competitive ST program and those undergoing respiratory muscle training using the flow-resistive IMT device employed in the present study; as yet, the causal mechanisms involved are undefined.     

Characteristics of the respiratory mechanical and muscle function of competitive breath-hold divers

Competitive breath-hold divers (BHD) employ glossopharyngeal insufflation (GI) to increase intrapulmonary oxygen stores and prevent the lungs from dangerous compressions at great depths. Glossopharyngeal insufflation is associated with inflation of the lungs beyond total lung capacity (TLC). It is currently unknown whether GI transiently over-distends the lungs or adversely affects lung elastic properties in the long-term. Resting lung function, ventilatory drive, muscle strength, and lung compliance were measured in eight BHD who performed GI since 5.5 (range 2–6) years on average, eight scuba divers, and eight control subjects. In five BHD subsequent measures of static lung compliance (Cstat) were obtained after 1 and 3 min following GI. Breath-hold divers had higher than predicted ventilatory flows and volumes and did not differ from control groups with regard to gas transfer, inspiratory muscle strength, and lung compliance. A blunted response to CO₂ was obtained in BHD as compared to control groups. Upon GI there was an increase in mean vital capacity (VC_GI) by 1.75 ± 0.85 (SD) L compared to baseline (p < 0.001). In five BHD Cstat raised from 3.7 (range 2.9–6.8) L/kPa at baseline to 8.1 (range 3.4–21.2) L/kPa after maximal GI and thereafter gradually decreased to 5.6 (range 3.3–8.1) L/kPa after 1 min and 4.2 (range 2.7–6.6) L/kPa after 3 min (p < 0.01). We conclude that in experienced BHD there is a transient alteration in lung elastic recoil. Resting lung function did not reveal a pattern indicative of altered lung ventilatory or muscle function.     

Intense hypoxic cycle exercise does not alter lung density in competitive male cyclists

We tested the hypothesis that intense short duration hypoxic exercise would result in an increase in extravascular lung water (EVLW), as evidenced by an increase in lung density. Using computed tomography (CT), baseline lung density was obtained in eight highly trained male cyclists (mean ± SD: age = 28 ± 8 years; height = 180 ± 9 cm; mass = 71.6 ± 8.2 kg; = 65.0 ± 5.2 ml kg min⁻¹). Subjects then completed an intense hypoxic exercise challenge on a cycle ergometer and metabolic data, HR and %S_pO₂ were recorded throughout. While breathing 15% O₂, subjects performed five 3 km cycling intervals (mean power, 286 ± 20 W; HR = 91 ± 4% HR_max) separated by 5 min of recovery. From a resting hypoxic S_pO₂ of 92 ± 4%, subjects further desaturated during exercise to 76 ± 3%. CT scans were repeated 76 ± 10 min (range 63–88 min) following the completion of exercise. There was no change in lung density from pre (0.18 ± 0.02 g ml⁻¹) to post-exercise (0.18 ± 0.04 g ml⁻¹). The substantial reduction in S_pO₂ may be explained by a number of potential mechanisms, including decreased pulmonary diffusion capacity, alveolar hypoventilation, reduced red cell transit time, ventilation/perfusion inequality or a temperature and pH induced rightward-shift in the oxyhaemoglobin dissociation curve. Alternatively, the integrity of the blood gas barrier may have been disrupted without any measurable increase in lung density.     

Nutritional Status is Related to Fat-Free Mass, Exercise Capacity and Inspiratory Strength in Severe Chronic Obstructive Pulmonary Disease Patients

INTRODUCTION:

Being overweight or obese is associated with a higher rate of survival in patients with advanced chronic obstructive pulmonary disease (COPD). This paradoxical relationship indicates that the influence of nutritional status on functional parameters should be further investigated.

OBJECTIVE:

To investigate the impact of nutritional status on body composition, exercise capacity and respiratory muscle strength in severe chronic obstructive pulmonary disease patients.

METHODS:

Thirty-two patients (nine women) were divided into three groups according to their body mass indices (BMI): overweight/obese (25 ≤ BMI ≤ 34.9 kg/m², n=8), normal weight (18.5 ≤ BMI ≤ 24.9 kg/m², n=17) and underweight (BMI <18.5 kg/m², n=7). Spirometry, bioelectrical impedance, a six-minute walking distance test and maximal inspiratory and expiratory pressures were assessed.

RESULTS:

Airway obstruction was similar among the groups (p=0.30); however, overweight/obese patients had a higher fat-free mass (FFM) index [FFMI=FFM/body weight² (mean±SEM: 17±0.3 vs. 15±0.3 vs. 14±0.5 m/kg², p<0.01)], exercise capacity (90±8 vs. 79±6 vs. 57±8 m, p=0.02) and maximal inspiratory pressure (63±7 vs. 57±5 vs. 35±8 % predicted, p=0.03) in comparison to normal weight and underweight patients, respectively. In addition, on backward multiple regression analysis, FFMI was the unique independent predictor of exercise capacity (partial r=0.52, p<0.01).

CONCLUSIONS:

Severe chronic obstructive pulmonary disease (COPD) patients who were overweight or obese had a greater FFM, exercise capacity and inspiratory muscle strength than patients with the same degree of airflow obstruction who were of normal weight or underweight, and higher FFM was independently associated with higher exercise capacity. These characteristics of overweight or obese patients might counteract the drawbacks of excess weight and lead to an improved prognosis in COPD.     

Inspiratory muscle training improves 100 and 200 m swimming performance

Inspiratory muscle training (IMT) has been shown to improve time trial performance in competitive athletes across a range of sports. Surprisingly, however, the effect of specific IMT on surface swimming performance remains un-investigated. Similarly, it is not known whether any ergogenic influence of IMT upon swimming performance is confined to specific race distances. To determine the influence of IMT upon swimming performance over 3 competitive distances, 16 competitive club-level swimmers were assigned at random to either an experimental (pressure threshold IMT) or sham IMT placebo control group. Participants performed a series of physiological and performance tests, before and following 6 weeks of IMT, including (1) an incremental swim test to the limit of tolerance to determine lactate, heart rate and perceived exertion responses; (2) standard measures of lung function (forced vital capacity, forced expiratory volume in 1 s, peak expiratory flow) and maximal inspiratory pressure (MIP); and (3) 100, 200 and 400 m swim time trials. Training utilised a hand-held pressure threshold device and consisted of 30 repetitions, twice per day. Relative to control, the IMT group showed the following percentage changes in swim times: 100 m, −1.70% (90% confidence limits, ±1.4%), 200 m, −1.5% (±1.0), and 400 m, 0.6% (±1.2). Large effects were observed for MIP and rates of perceived exertion. In conclusion, 6 weeks of IMT has a small positive effect on swimming performance in club-level trained swimmers in events shorter than 400 m.     

Inspiratory muscle training abolishes the blood lactate increase associated with volitional hyperpnoea superimposed on exercise and accelerates lactate and oxygen uptake kinetics at the onset of exercise

We examined the effects of inspiratory muscle training (IMT) upon volitional hyperpnoea-mediated increases in blood lactate ([lac(-)](B)) during cycling at maximal lactate steady state (MLSS) power, and blood lactate and oxygen uptake kinetics at the onset of exercise. Twenty males formed either an IMT (n = 10) or control group (n = 10). Prior to and following a 6-week intervention, two 30 min trials were performed at MLSS (207 ± 28 W), determined using repeated 30 min constant power trials. The first was a reference trial, whereas during the second trial, from 20 to 28 min, participants mimicked the breathing pattern commensurate with 90% of the maximal incremental exercise test minute ventilation ([Formula: see text]). Prior to the intervention, the MLSS [lac(-)](B) was 3.7 ± 1.8 and 3.9 ± 1.6 mmol L(-1) in the IMT and control groups, respectively. During volitional hyperpnoea, [Formula: see text] increased from 79.9 ± 9.5 and 76.3 ± 15.4 L min(-1) at 20 min to 137.8 ± 15.2 and 135.0 ± 19.7 L min(-1) in IMT and control groups, respectively; [lac(-)](B) concurrently increased by 1.0 ± 0.6 (+27%) and 0.9 ± 0.7 mmol L(-1) (+25%), respectively (P < 0.05). Following the intervention, maximal inspiratory mouth pressure increased 19% in the IMT group only (P < 0.01). Following IMT only, the increase in [lac(-)](B) during volitional hyperpnoea was abolished (P < 0.05). In addition, the blood lactate (-28%) and phase II oxygen uptake (-31%) kinetics time constants at the onset of exercise and the MLSS [lac(-)](B) (-15%) were reduced (P < 0.05). We attribute these changes to an IMT-mediated increase in the oxidative and/or lactate transport capacity of the inspiratory muscles.     

The effect of inspiratory muscle training upon maximum lactate steady-state and blood lactate concentration

Several studies have reported that improvements in endurance performance following respiratory muscle training (RMT) are associated with a decrease in blood lactate concentration ([Lac]_B). The present study examined whether pressure threshold inspiratory muscle training (IMT) elicits an increase in the cycling power output corresponding to the maximum lactate steady state (MLSS). Using a double-blind, placebo-controlled design, 12 healthy, non-endurance-trained male participants were assigned in equal numbers to an experimental (IMT) or sham training control (placebo) group. Cycling power output at MLSS was initially identified using a lactate minimum protocol followed by a series of constant power output rides (2.5% increments) of 29.5 min duration; MLSS was reassessed following six weeks of IMT or sham IMT. Maximum inspiratory mouth pressure increased significantly (26%) in the IMT group, but remained unchanged in the placebo group. The cycling power output corresponding to MLSS remained unchanged in both groups after the intervention. After IMT, [Lac]_B decreased significantly at MLSS power in the IMT group [–1.17 (1.01) mmol l^–1 after 29.5 min of cycling; mean (SD)], but remained unchanged in the placebo group [+0.37 (1.66) mmol l^–1]. These data support previous observations that IMT results in a decrease in [Lac]_B at a given intensity of exercise. That such a decrease in [Lac]_B was not associated with a substantial (>2.5%) increase in MLSS power is a new finding suggesting that RMT-induced increases in exercise tolerance and reductions in [Lac]_B are not ascribable to a substantial increase in the lactate threshold.     

The importance of intima-media thickness (IMT) measurements in monitoring of atherosclerosis progress after myocardial infarction

PurposeIntima-media thickness (IMT) assessed in peripheral arteries correlates with presence and progression of atherosclerosis in coronary arteries. IMT measurements may help to select high risk patients and evaluate the efficacy of the therapy used.AIMThe aim of the study was to assess the usefulness of ultrasonographic measurement of IMT in atherosclerosis progress monitoring in patients after myocardial infarction (MI).Patients and Methods70 men (mean age 52.8 ± 8.4) treated with PCI due to acute myocardial infarction, were enrolled in the study. All subjects underwent ultrasound examination of the IMT complex of: common carotid artery (CCA), carotid bulb and common femoral artery (CFA) during hospitalization and follow-up period (3.83 ± 1.29 years).ResultsDuring the follow-up 3 patients (4.3%) were not on any medications, 8 pts (11.4%) were on reduced doses of β-blocker, statin or ACE-I (non-compliant pts.). The others (compliant) – 59 pts (84.3%) received standard pharmacological treatment after MI. Nevertheless, an increase of IMT complex value after follow-up compared to initial IMT values of all examined peripheral arteries was observed (respectively: IMT CCA – 0.91±0.26 vs 1.10±0.36, p=0.002, IMT of carotid bulb – 1.31±0.55 vs 1.82±0.69, p=0.012, IMT CFA – 1.38±0.64 vs 1.97±0.75, p=0.014). Non-compliant patients had statistically significant higher IMT values after follow-up when compared to compliant subjects (1.62 vs 1.20, p= 0.017). Patients with higher IMT values were reported to have cardiac events more frequently during the follow-up (p<0.05).ConclusionsOur results provide evidence that ultrasonographic IMT complex assessment of peripheral arteries in everyday clinical practice allows monitoring efficacy of pharmacological therapy in CAD patients after MI. They also suggest treatment intensification if necessary.     

Inspiratory muscle training reduces blood lactate concentration during volitional hyperpnoea

Although reduced blood lactate concentrations ([lac(-)](B)) have been observed during whole-body exercise following inspiratory muscle training (IMT), it remains unknown whether the inspiratory muscles are the source of at least part of this reduction. To investigate this, we tested the hypothesis that IMT would attenuate the increase in [lac(-)](B) caused by mimicking, at rest, the breathing pattern observed during high-intensity exercise. Twenty-two physically active males were matched for 85% maximal exercise minute ventilation (.V(E) max) and divided equally into an IMT or a control group. Prior to and following a 6 week intervention, participants performed 10 min of volitional hyperpnoea at the breathing pattern commensurate with 85% .V(E) max. The IMT group performed 6 weeks of pressure-threshold IMT; the control group performed no IMT. Maximal inspiratory mouth pressure increased (mean +/- SD) 31 +/- 22% following IMT and was unchanged in the control group. Prior to the intervention in the control group, [lac(-)](B) increased from 0.76 +/- 0.24 mmol L(-1) at rest to 1.50 +/- 0.60 mmol L(-1) (P < 0.05) following 10 min volitional hyperpnoea. In the IMT group, [lac(-)](B) increased from 0.85 +/- 0.40 mmol L(-1) at rest to 2.02 +/- 0.85 mmol L(-1) following 10 min volitional hyperpnoea (P < 0.05). After 6 weeks, increases in [lac(-)](B) during volitional hyperpnoea were unchanged in the control group. Conversely, following IMT the increase in [lac(-)](B) during volitional hyperpnoea was reduced by 17 +/- 37% and 25 +/- 34% following 8 and 10 min, respectively (P < 0.05). In conclusion, increases in [lac(-)](B) during volitional hyperpnoea at 85% .V(E) max were attenuated following IMT. These findings suggest that the inspiratory muscles were the source of at least part of this reduction, and provide a possible explanation for some of the IMT-mediated reductions in [lac(-)](B), often observed during whole-body exercise.     

Ventilatory responses to exercise training in obese adolescents

The aim of this study was to examine ventilatory responses to training in obese adolescents. We assessed body composition, pulmonary function and ventilatory responses (among which expiratory flow limitation and operational lung volumes) during progressive cycling exercise in 16 obese adolescents (OB) before and after 12 weeks of exercise training and in 16 normal-weight volunteers. As expected, obese adolescents' resting expiratory reserve volume was lower and inversely correlated with thoraco-abdominal fat mass (r=-0.74, p<0.0001). OB presented lower end expiratory (EELV) and end inspiratory lung volumes (EILV) at rest and during submaximal exercise, and modest expiratory flow limitation. After training, OB increased maximal aerobic performance (+19%) and maximal inspiratory pressure (93.7±31.4 vs 81.9±28.2cmH(2)O, +14%) despite lack of decrease in trunk fat and body weight. Furthermore, EELV and EILV were greater during submaximal exercise (+11% and +9% in EELV and EILV, respectively), expiratory flow limitation delayed but was not accompanied by increased V(T). However, submaximal exertional symptoms (dyspnea and leg discomfort) were significantly decreased (-71.3% and -70.7%, respectively). Our results suggest that exercise training can improve pulmonary function at rest (static inspiratory muscle strength) and exercise (greater operating lung volumes and delayed expiratory flow limitation) but these modifications did not entirely account for improved dyspnea and exercise performance in obese adolescents.     

Acute effects of exercise posture on executive function in transient ischemic attack patients

In patients with stroke or transient ischemic attacks (TIA), a decline in executive function may limit an individual's ability to process motor tasks and relearn motor skills. The purpose of this study was to assess the acute effect of exercise posture (seated vs. supine cycle ergometry) on executive function and prefrontal cortex perfusion in patients with TIA. Eleven TIA patients (65 ± 10 years) and 15 age‐matched, healthy controls (HC; 62 ± 7 years) completed two exercise tests to maximal capacity (one seated, one supine) and two 30‐min submaximal exercise tests (one seated, one supine). Executive function was assessed prior to and following (1.5 min post, 15 min post) the submaximal exercise tests using a Stroop task. Prefrontal cortex perfusion (total hemoglobin) was continuously recorded using near‐infrared spectroscopy. There was no Posture (seated, supine) × Group (TIA, HC) interaction for the Stroop task (p > .05). HC completed Stroop tasks significantly faster than TIA (51.9[SD = 10.3] vs. 64.2[8.5] s, respectively), while Stroop completion time significantly improved between baseline and 1.5 min post (61.3[10] vs. 58.1[9.4] s, respectively) and 1.5 min post and 15 min post (54.8[8.9] s). Posture and group had no significant influence on prefrontal cortex perfusion (p > .05). In summary, executive function improves to a similar extent in TIA and age‐matched, healthy controls following an acute bout of exercise, regardless of exercise posture. As acute improvements in executive function were maintained for 15 min, there could be an important window of opportunity for assigning executive tasks following exercise rehabilitation for patients with TIA.     

Respiratory muscle training reduces the work of breathing at depth

Resistance respiratory muscle training (RRMT) increases respiratory muscle and swimming performance at depths down to 17 msw. It is unknown if RRMT improves swimming performance at greater depths and if the improvements are associated with a reduced work of breathing (WOB), altered respiratory mechanics and/or improved respiratory muscle performance. Eight male subjects (30.3 ± 6.0 years) were tested swimming underwater in a hyperbaric chamber at 37 m of depth against a pre-determined load (70% [(V)\dot]_{\textO 2} \dot{V}_{{{\text{O}}_{ 2} }} ) until exhausted. End expiratory lung volume (EELV) was determined by subtracting inspiratory capacity from total lung capacity throughout the swims. The mechanical WOB on the lung was calculated as the integrated product of the transpulmonary pressure and ventilatory flow. Maximal expiratory (P _EMAX) and inspiratory pressures (P _IMAX) were measured pre- and post-RRMT. RRMT was performed every 30 s against spring loaded inspiratory and expiratory valves 30 min/day, 5 days/week, for 4 weeks. RRMT increased P _IMAX and P _EMAX by 40% (110 ± 11 cmH₂O (SD) vs. 155 ± 22, p < 0.001) and 30% (148 ± 33 cmH₂O vs. 192 ± 49, p < 0.001), respectively, respiratory endurance by 75% (19.7 ± 15.4 min vs. 34.4 ± 27.3, p = 0.010), and swimming endurance by 87% (26.4 ± 9.7 min vs. 49.4 ± 21.6, p = 0.004). The longer swimming time was associated with reduced [(V)\dot]_\textE \dot{V}_{\text{E}} and [(V)\dot]_\textA \dot{V}_{\text{A}} (p < 0.001), f _b (p < 0.001), [(V)\dot]_\textCO2 \dot{V}_{{{\text{CO}}_{2} }} (p < 0.001) and WOB (p < 0.001). There were no changes in EELV post-RRMT. These results suggest the improved exercise performance post-RRMT was associated with stronger respiratory muscles, a decreased f _b, and a reduced WOB.     

Pulmonary function,exercise capacity and dyspnea in patients 7 ​years after Nuss surgery

PurposePectus excavatum is a frequent thoracic malformation increasingly treated with minimally invasive methods (MIRPE), which are performed for cardio-respiratory problems and in some centers also for esthetic considerations. Theoretically, MIRPE may increase thoracic elastic recoil, work of breathing and cause emphysema. The aim of the present study was to determine whether teenagers who underwent MIRPE may expect normal thoracic cage development, cardio-respiratory function, exercise capacity and asymptomatic functioning.Material and methodsFifty five patients (21.1 ?± ?3.0 years) who underwent MIRPE between 2000 and 2010 were assessed 6.8 (±2.4) years after surgery. Controls were matched for sex, age and height to the intervention participants. Spirometry, body plethysmography, diffusion capacity and the 6 ?min walking test (6MWT) were performed. Anteroposterior (AP) and transverse chest diameters were measured.ResultsParticipants who underwent MIRPE had normal pulmonary function, and exercise capacity. After adjustment for potential confounders, the intervention group had lower mean BMI [–1.88 ?± ?0.56 (kg/m²); p ?= ?0.001] and chest AP diameter [-2.79 ?± ?0.57 (cm); p ?< ?0.001], but higher residual volume (RV%) [12.98 ?± ?5.31 (%); p ?= ?0.001], RV% total lung capacity (TLC) [5.56 ?± ?0.92 (%); p ?< ?0.001], forced expiratory volume in 1 ?s/forced vital capacity (FEV₁/FVC) [2.64 ?± ?1.28 (%); p ?= ?0.039] and 6MWT distance [29.10 ?± ?13.02 (m); p ?= ?0.025].ConclusionsYoung adults who undergo MIRPE may expect normal pulmonary function and exercise capacity. Observed differences in air trapping require further assessment in terms of emphysema development risk.