Towards an individualized protocol for workload increments in cardiopulmonary exercise testing in children and adolescents with cystic fibrosis

AbstractBackgroundThere is no single optimal exercise testing protocol for children and adolescents with cystic fibrosis (CF) that differs widely in age and disease status. The aim of this study was to develop a CF-specific, individualized approach to determine workload increments for a cycle ergometry testing protocol.MethodsA total of 409 assessments consisting of maximal exercise data, anthropometric parameters, and lung function measures from 160 children and adolescents with CF were examined. 90% of the database was analyzed with backward linear regression with peak workload (Wpeak) as the dependent variable. Afterwards, we [1] used the remaining 10% of the database (model validation group) to validate the model's capacity to predict Wpeak and [2] validated the protocol's ability to provide a maximal effort within a 10±2minute time frame in 14 adolescents with CF who were tested using this new protocol (protocol validation group).ResultsNo significant differences were seen in Wpeak and predicted Wpeak in the model validation group or in the protocol validation group. Eight of 14 adolescents with CF in the protocol validation group performed a maximal effort, and seven of them terminated the test within the 10±2minute time frame. Backward linear regression analysis resulted in the following equation: Wpeak (W)=−142.865+2.998×Age (years)−19.206×Sex (0=male; 1=female)+1.328×Height (cm)+23.362×FEV1 (L) (R=.89; R2=.79; SEE=21). Bland–Altman analysis showed no systematic bias between the actual and predicted Wpeak.ConclusionWe developed a CF-specific linear regression model to predict peak workload based on standard measures of anthropometry and FEV1, which could be used to calculate individualized workload increments for a cycle ergometry testing protocol

Позиционирование изображений фотошаблонов в системах автоматизированного оптического контроля

Разработана система автоматизированного оптического позиционирования фотошаблонов интегральных схем, которая имеет высокие показатели помехоустойчивости и точности

MRI-based screening for metabolic insufficiency of leg muscle during aerobic exercise in Cystic Fibrosis

There is evidence for mitochondrial dysfunction in various tissues in Cystic Fibrosis (CF) including muscle. Among others, a slow rate of high-energy phosphate resynthesis following exercise involving single limb muscle activity was found in human CF using in vivo 31P magnetic resonance spectroscopy (MRS). This raises the question whether this outcome would be ameliorated versus exacerbated if instead an exercise regime is used that puts a significant cardiopulmonary load on the body as in running or bicycling. This is of interest because exercise therapy is commonly prescribed in CF. To investigate this matter, ten pediatric CF patients (age 12–16 years) and healthy peers performed two ramp exercise tests to volitional exhaustion using a bicycle ergometer fit for use inside a MR scanner. Endurance, VO2max and heart rate were determined in the exercise laboratory. Quadriceps muscle energy-and acid/base balance during exercise and recovery were measured on a separate day using MR imaging-based 31P MRS. This study brings together for the first time this powerful biomedical imaging platform and whole body exercise testing in the clinical setting of human CF

Exercise testing, limitation and training in patients with cystic fibrosis. A personalized approach

Exercise testing and training are cornerstones in regular CF care. However, no consensus exists in literature about which exercise test protocol should be used for individual patients. Furthermore, divergence exists in insights about both the dominant exercise limiting mechanisms and the possibilities to aim and institute exercise training strategies, based on these individual limitations. Therefore, this thesis intends to expand current knowledge in [1] alternative exercise test procedures in CF; [2] exercise limiting mechanisms in CF; and [3] exercise training of the inspiratory and skeletal muscles. In the first part of this research report we describe two different methodologies of exercise testing that were developed in patients with CF and were analyzed for their usefulness. Chapter 2 described the verification of VO2peak obtained during traditional cardiopulmonary exercise testing (CPET) with a supramaximal exercise procedure. The development and the validity of an individualized exercise test protocol in children and adolescents with CF are described in Chapter 3. Subsequently, Chapter 4 presents an alternative method to estimate VO2peak developed and validated in adolescents with CF. The major findings of the first part of the thesis: · The VO2peak measured with traditional CPET seems to reflect the true VO2peak in adolescents with CF (Chapter 2), · W­peak can be reliably predicted with standard measured anthropometric variables (Chapter 3), · The predicted Wpeak can be reliably used as guideline to individualize workload increments during CPET (Chapter 3), · VO2peak can be reliably predicted from Wpeak obtained with a traditional CPET combined with gender in adolescents with CF without the necessity of direct gas analysis (Chapter 4). The second part of this thesis focuses on two previously described exercise limiting mechanisms in patients with CF. Chapter 5 presents a study of the possible role of static hyperinflation as an exercise limiting factor, while Chapter 6 describes a study of the possible role of a CF specific locomotor skeletal muscle dysfunction. The major findings of the second part of the thesis: •The presence of static hyperinflation alone does not strongly influence ventilatory limitations during (peak) exercise in adolescents with CF (Chapter 5), •The RV/TLC > 30% criterion for static hyperinflation is a slightly stronger predictor of Wpeak/kg and VO2peak/kg than the traditional FEV1%pred (Chapter 5), •Oxidative exercise metabolism and oxygenation kinetics in clinically stable adolescents with CF with mild lung function impairment and without systemic inflammation seem to be comparable to healthy controls (Chapter 6). The third part of this thesis (Chapter 7) presents a study of the effects of two different types of exercise interventions, i.e. short-term, home-based inspiratory muscle training (IMT) and short-term, home-based peripheral muscle training programin patients with CF and the possible preconditioning effect of inspiratory muscle training prior to general exercise training. The major findings of this part of the thesis: •A six-week, home-based, non-supervised IMT program does not significantly decrease work of breathing in patients with mild lung function impairment compared to control patients, •Six weeks, non-supervised, peripheral muscle training was insufficient effective to increase exercise capacity in mild-moderate patients with CF

Ventilatory response to exercise in adolescents with cystic fibrosis and mild-to-moderate airway obstruction

Data regarding the ventilatory response to exercise in adolescents with mild-to-moderate cystic fibrosis (CF) are equivocal. This study aimed to describe the ventilatory response during a progressive cardiopulmonary exercise test (CPET) up to maximal exertion, as well as to assess the adequacy of the ventilatory response for carbon dioxide (CO2) exhalation. Twenty-two adolescents with CF (12 boys and 10 girls; mean +/- SD age: 14.3 +/- 1.3 years; FEV1: 78.6 +/- 17.3% of predicted) performed a maximal CPET. For each patient, data of a sex- and age matched healthy control was included (12 boys and 10 girls; mean +/- SD age: 14.3 +/- 1.4 years). At different relative exercise intensities of 25%, 50%, 75%, and 100% of peak oxygen uptake (VO2peak), breathing pattern, estimated ventilatory dead space ventilation (VD/VT ratio), minute ventilation (VE) to CO2 production relationship (VE/VCO2-slope), partial end-tidal CO2 tension (PETCO2), and the VE to the work rate (VE/WR) ratio were examined. VO2peak was significantly reduced in CF patients (P = 0.01). We found no differences in breathing pattern between both groups, except for a significantly higher VE at rest and a trend towards a lower VE at peak exercise in patients with CF. Significantly higher values were found for the estimated VD/VT ratio throughout the CPET in CF patients (P < 0.01). VE/VCO2-slope and PETCO2 values differed not between the two groups throughout the CPET. VE/WR ratio values were significantly higher in CF during the entire range of the CPET (P < 0.01). This study found an exaggerated ventilatory response (high VE/WR ratio values), which was adequate for CO2 exhalation (normal VE/VCO2-slope and PETCO2 values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction

Extended steep ramp test normative values for 19-24-year-old healthy active young adults

Purpose To extend currently available sex and age-specific normative values in children and adolescents for the peak work rate (WRpeak) attained at the steep ramp test (SRT) to healthy active young adults. Methods Healthy male and female participants aged between 19 and 24 years were recruited. After screening and anthropometric measurements, participants performed a SRT on a cycle ergometer (increments of 25 W/10 s), monitoring and recording SRT-WRpeak, heart rate (HR), and blood pressure (BP) at rest and directly after peak exercise. Results Fifty-seven participants (31 males and 26 females; median age of 21.3 years) volunteered and were tested. Anthropometrics, resting BP and lung function were all within normal ranges. Ninety-three percent of the participants attained a peak HR (HRpeak) > 80% of predicted (mean HRpeak 87 +/- 5% of predicted). No differences were found in resting and peak exercise variables between females and males, except for absolute SRT-WRpeak (350 W [Q1: 306; Q3: 371] and 487 W [Q1: 450; Q3: 517], respectively) and SRT-WRpeak normalized for body mass (relative SRT-WRpeak; 5.4 +/- 0.5 and 6.2 +/- 0.6 W/kg, respectively). Low-to-moderate correlations (rho [0.02-0.71]) were observed between SRT-WRpeak and anthropometric variables for females and males separately. Extended reference curves (8-24-year-old subjects) for SRT performance show different trends between male and female subjects when modelled against age, body height, and body mass. Conclusions The present study provides sex-, age-, body height-, and body mass-related normative values (presented as reference centiles) for absolute and relative SRT performance throughout childhood and early adulthood