Determinants of aerobic and anaerobic exercise performance in cystic fibrosis

Mechanisms of ventilatory limitation to maximum exercise in children and adolescents with chronic airway diseases

INTRODUCTION

Exercise intolerance is common in chronic airway diseases (CAD), but its mechanisms are still poorly understood. The aim of this study was to evaluate exercise capacity and its association with lung function, ventilatory limitation, and ventilatory efficiency in children and adolescents with cystic fibrosis (CF) and asthma when compared to healthy controls.

METHODS

Cross-sectional study including patients with mild-to-moderate asthma, CF and healthy children and adolescents. Anthropometric data, lung function (spirometry) and exercise capacity (cardiopulmonary exercise testing) were evaluated. Primary outcomes were peak oxygen consumption (VO2 peak), forced expiratory volume in 1 s (FEV1 ), breathing reserve (BR), ventilatory equivalent for oxygen consumption (VE /VO2 ) and for carbon dioxide production (VE /VCO2 ), both at the ventilatory threshold (VT1 ) and peak exercise.

RESULTS

Mean age of 147 patients included was 11.8 ± 3.0 years. There were differences between asthmatics and CF children when compared to their healthy peers for anthropometric and lung function measurements. Asthmatics showed lower VO2 peak when compared to both healthy and CF subjects, although no differences were found between healthy and CF patients. A lower BR was found when CF patients were compared to both healthy and asthmatic. Both CF and asthmatic patients presented higher values for VE /VO2 and VE /VCO2 at VT1 when compared to healthy individuals. For both VE /VO2 and VE /VCO2 at peak exercise CF patients presented higher values when compared to their healthy peers.

CONCLUSION

Patients with CF achieved good exercise capacity despite low ventilatory efficiency, low BR, and reduced lung function. However, asthmatics reported reduced cardiorespiratory capacity and normal ventilatory efficiency at peak exercise. These results demonstrate differences in the mechanisms of ventilatory limitation to maximum exercise testing in children and adolescents with CAD.

Home Based Rehabilitation in Children and Adolescents with Cystic Fibrosis: A Systematic Review with Meta-Analysis and Grade Recommendations

OBJECTIVE

The objective of this study is to elucidate the effectiveness of home based rehabilitation (HBR) and compare its results with those obtained in conventional rehabilitation (CR) programs, carried out in clinics and/or outpatient clinics.

METHODS

Searches were conducted in five databases of randomized clinical trials. Study selection, data extraction, and assessment of the methodological quality of included studies were conducted independently by two reviewers, with discrepancies resolved by a third reviewer.

RESULTS

The results demonstrate post-intervention values favorable to the use of HBR when compared to control group in the outcomes of forced expiratory volume in 1 second (FEV1) (MD = 14% CI: 5.42 to 22.58, p = 0.001), forced vital capacity (FVC) (MD = 8.00% CI: 0.83 to 15.17, p = 0.03) and quality of life by the Cystic Fibrosis Questionnaire - revised in the categories (Child version score" (MD= 0.71%CI: 0.15 to 1.27, p = 0.01) and "Parent version score" (MD= 0.67%CI: 0.11 to 1.23, p = 0.02). Furthermore, we noticed an increase in the distance covered in the 6-minute walk test (MD= 34.75%CI: -8.00 to 77.50, p = 0.14), in favor of HBR.

CONCLUSIONS

We found that supervised or partially supervised HBR promotes improvements in FEV1, FVC and related quality of life in children and/or adolescents with cystic fibrosis.

Physical Activity and Quality of Life among Patients with Cystic Fibrosis

BACKGROUND

Physical activity (PA) improves exercise capacity, slows the decline in lung function, and enhances Quality of Life (QoL) in patients with cystic fibrosis (pwCF).

OBJECTIVES

The study aimed to evaluate PA and QoL among children with CF compared to healthy controls; the secondary aim was to assess the correlation between PA, QoL, and lung function (FEV1).

METHODS

Forty-five children and adolescents with CF and 45 age-matched controls completed two self-administered validated questionnaires: The Godin Leisure-Time Exercise Questionnaire (GLTEQ) and the DISABKIDS for QoL. Moreover, pwCF performed spirometry and multiple breath washout tests (MBW). In addition, weight, height, and BMI were recorded. The Godin Leisure-Time Exercise Questionnaire was used to evaluate physical activity; QOL was assessed using the DISABKIDS Questionnaire. The correlation of PA with QOL was assessed as well.

RESULTS

Mean age of the CF population was 13.22 (±4.6) years, mean BMI 19.58 (±4.1) kg/m2, mean FEV1% 91.15 ± 20.46%, and mean LCI 10.68 ± 4.08. 68% of the CF group were active, 27% were medium active, 5% were sedentary, while 83% of the control group were active and 17% were medium active. PwCF with higher PA scores showed significantly higher emotional health (r2: 0.414, p: 0.006) and total QOL score (r2: 0.372; p: 0.014). The PA score showed no significant correlation with FEV1% or LCI.

CONCLUSIONS

The children with CF showed satisfactory PA levels, which positively correlated to their QoL. More research is needed on the effect of increased levels of habitual physical activity to establish the decline in pulmonary function among pwCF.

The Comparison of Anaerobic Power using Two Tests in Patients with Cystic Fibrosis and Healthy Children

ABSTRACT Purpose: Cystic fibrosis (CF), a progressive and multi-systemic disease, causes reduced anaerobic performance. This study aimed to compare anaerobic power using two tests (Counter-movement Vertical Jump and Wingate Anaerobic Test) in CF patients and healthy children. Material and Methods: Eighteen CF and 18 healthy children were included in this prospective study. Knee extensor muscle strength and body composition were assessed with a digital handheld dynamometer and Tanita-BC 418, respectively. Anaerobic power was evaluated with Wingate Anaerobic Test (WAnT) and Counter-movement Vertical Jump (CMJ) using a triaxial accelerometer (G-Walk). Results: Maximum concentric power, peak speed, impact force, take-off force, and jump height were significantly worse in the CF group than in their healthy peers (p

High-intensity interval training accelerates oxygen uptake kinetics and improves exercise tolerance for individuals with cystic fibrosis

Background

Exercise training provides benefits for individuals with cystic fibrosis; however, the optimal program is unclear. High-intensity interval training is safe and effective for improving ‘functional capacity’ in these individuals with peak rate of O₂ uptake typically referenced. The ability to adjust submaximal rate of oxygen uptake (V̇O₂ kinetics) might be more important for everyday function because maximal efforts are usually not undertaken. Moreover, the ability of high-intensity training to accelerate V̇O₂ kinetics for individuals with cystic fibrosis could be enhanced with O₂ supplementation during training.

Methods

Nine individuals with cystic fibrosis completed incremental cycling to limit of tolerance followed by 8 weeks of high-intensity interval cycling (2 sessions per week x ~ 45 min per session) either with (n = 5; O2+) or without (AMB) oxygen supplementation (100%). Each session involved work intervals at 70% of peak work rate followed by 60 s of recovery at 35%. For progression, duration of work intervals was increased according to participant tolerance.

Results

Both groups experienced a significant increase in work-interval duration over the course of the intervention (O2+, 1736 ± 141 v. 700 ± 154 s; AMB, 1463 ± 598 v. 953 ± 253 s; P = 0.000); however, the increase experienced by O2+ was greater (P = 0.027). During low-intensity constant-work-rate cycling, the V̇O₂ mean response time was shortened post compared to pre training (O2+, 34 ± 11 v. 44 ± 9 s; AMB, 39 ± 14 v. 45 ± 17 s; P = 0.000) while during high-intensity constant-work-rate cycling, time to exhaustion was increased (O2+, 1628 ± 163 v. 705 ± 133 s; AMB, 1073 ± 633 v. 690 ± 348 s; P = 0.002) and blood [lactate] response was decreased (O2+, 4.5 ± 0.9 v. 6.3 ± 1.4 mmol^. L^− 1; AMB, 4.5 ± 0.6 v. 5.2 ± 1.4 mmol^. L^− 1; P = 0.003). These positive adaptations were similar regardless of gas inspiration during training.

Conclusion

Eight weeks of high-intensity interval training for patients with cystic fibrosis accelerated V̇O₂ kinetics and increased time to exhaustion. This provides some evidence that these patients may benefit from this type of exercise.

Trial registration

This study was retrospectively registered in the ISRTCN registry on 22/06/2019 (#ISRCTN13864650).

Evaluation of exercise capacity using two field tests in patients with metabolic syndrome

PURPOSE

Field tests are popular for assessing exercise capacity because they are practical and have established validity. The objective of this study was to compare physiological responses and exercise performance of patients with metabolic syndrome in two field tests of exercise capacity.

MATERIAL AND METHODS

Forty-seven patients diagnosed with metabolic syndrome participated in this cross-sectional study. Exercise capacity was assessed using incremental shuttle walk test and six-minute walk test. Factors determining exercise capacity and agreement between the two tests were also investigated.

RESULTS

Metabolic syndrome patients achieved a significantly greater percentage of predicted maximal heart rate, blood pressure, and longer distance in the incremental shuttle walk test than in the six-minute walk test (p < 0.001). Gender and body mass index explained 48.5% of the variance in six-minute walk test distance (R = 0.697, R² = 0.485, F_(2-46) = 20.737, p < 0.001). Body mass index and fat-free mass explained 55% of the variance in incremental shuttle walk test distance (R = 0.746, R²= 0.557, F_(2-46) = 27.623, p < 0.001).

CONCLUSIONS

Despite the agreement in the percentages of predicted maximal heart rate during these two field tests, the incremental shuttle walk test may be a better assessment tool than the six-minute walk test because it elicits more pronounced and definitive physiological responses to exercise tolerance in patients with metabolic syndrome.IMPLICATIONS FOR REHABILITATIONThe incremental shuttle walk test can be used to evaluate exercise capacity in metabolic syndrome.The incremental shuttle walk test elicits greater physiological responses than the six-minute walk test.The incremental shuttle walk test may be preferable over the six-minute walk test in investigating exercise capacity.Both tests can guide and assist in the evaluation of this patient population in clinical practice.Body mass index affected distance in both exercise tests.

Airway clearance physiotherapy improves ventilatory dynamics during exercise in patients with cystic fibrosis: a pilot study

BACKGROUND

Airflow limitation and dynamic hyperinflation may limit exercise capacity in patients with cystic fibrosis (CF). The aim was to investigate whether the undertaking of airway clearance physiotherapy (ACT) prior to cardiopulmonary exercise testing (CPET) results in improvements in exercise capacity.

METHODS

A prospective randomised, cross-over pilot study was performed in children aged >9 years. Spirometry, plethysmography and CPET were performed on two separate occasions-one test with ACT prior to CPET and the other without.

RESULTS

12 patients with CF were included in the study with a mean (SD) age of 12.83 (1.85) years. No significant difference in peak oxygen uptake (VO₂) was found between the tests. However, lower minute ventilation (V_E) and ventilatory equivalents (V_EVO₂ and V_EVCO₂) at ventilatory threshold (VT) were noted when ACT was undertaken prior to CPET. The mean(SD) V_E (L/min) at VT was 26.67 (5.49) vs 28.92 (6.3) (p=0.05), V_EVO₂ (L/min) at VT was 24.5 (1.75) vs 26.05 (2.5) (p=0.03) and V_EVCO₂ (L/min) at VT was 26.58 (2.41) vs 27.98 (2.11) (p=0.03).

CONCLUSIONS

These pilot data suggest that ACT prior to exercise may lead to improved ventilatory dynamics during exercise in individuals with CF.

Reduced anaerobic and aerobic performance in children with primary ciliary dyskinesia

Primary ciliary dyskinesia (PCD) restricts lifestyle and increases morbidity. The aim of the study was to investigate anaerobic and aerobic performance in children with PCD and their healthy counterparts. Thirty-one children with PCD and 29 age- and sex-matched healthy subjects were studied. Pulmonary function, hand grip strength (HGS), quadriceps strength (QMS), physical activity, anaerobic capacity (muscle power sprint test), and aerobic performance (modified shuttle walk test (MSWT)) were determined. Pulmonary function, HGS, QMS, mean anaerobic power (MAP), and MSWT distance in PCD were significantly lower than those of healthy subjects (p < 0.05). In PCD, the MAP was significantly correlated with age, FEV₁, and the mean kcal for 3 days (p < 0.05), and age was its independent predictor (p < 0.05). The MSWT distance was significantly related to gender and weight (p < 0.05), and gender was selected as its independent predictor (p < 0.05). In healthy controls, the MAP was significantly associated with age, gender, FVC, FEV₁, HGS, QMS, and the mean kcal for three days (p < 0.05). The MSWT distance was significantly related to weight and body mass index in healthy group (p < 0.05).

CONCLUSION

Anaerobic and aerobic performance is impaired in PCD from the early stages. Age determines anaerobic performance. Gender is the determinant of aerobic performance. Whether skeletal muscle characteristics and sex-related changes in body composition affect anaerobic and aerobic capacity in PCD children warrants further study. What is Known: • Exercise performance is determined by anaerobic and aerobic power. • Few studies have shown that PCD patients have lower aerobic performance which is associated with impaired lung function. What is New: • The present research indicated that both anaerobic and aerobic exercise capacity determined using field testing is impaired in PCD from the early stages. • Anaerobic capacity was found to be independently associated with age in PCD. Higher aerobic performance is independently associated with male gender.

Static hyperinflation is associated with ventilatory limitation and exercise tolerance in adult cystic fibrosis

INTRODUCTION

Lung hyperinflation is a potential mechanism limiting exercise tolerance. However, available data on the impact of static hyperinflation on exercise performance in adult cystic fibrosis are lacking. Furthermore, the relative contribution of both static and dynamic hyperinflation to exercise performance is unknown.

OBJECTIVES

The aim of this study was to determine the impact of static hyperinflation on exercise tolerance and lung dynamics in adult cystic fibrosis.

METHODS

Clinical data of 107 adult patients with cystic fibrosis, including pulmonary function, lung volumes and cardiopulmonary exercise from the Toronto Cystic Fibrosis database, were collected and analyzed. Patients were classified as having static hyperinflation with a residual volume to total lung capacity (RV/TLC) ratio of 30% or greater.

RESULTS

Patients with static hyperinflation demonstrated a significant reduction in exercise performance [peak oxygen uptake (% predicted) 70 ± 17 vs 80 ± 17; P = .006] and were more likely to experience ventilatory limitation when exercising (Fisher's exact test P < .001). Correlation analysis showed significant relationships between measures of static hyperinflation [RV/TLC ratio (%)] and exercise performance [peak oxygen uptake (% predicted); r = -.38, P < .001] and dynamic hyperinflation (r = -.35, P < .001). Multiple linear regression showed that the contribution of static hyperinflation to exercise performance [peak oxygen uptake (% predicted)] was greater than that of airway obstruction (forced expiratory volume in 1 second).

CONCLUSION

Clinicians working with this patient group in a pulmonary rehabilitation or health care setting may wish to consider using measures of static hyperinflation as end points to determine program or treatment efficacy.

CFTR Genotype and Maximal Exercise Capacity in Cystic Fibrosis: A Cross-sectional Study

RATIONALE

Cystic fibrosis transmembrane conductance regulator (CFTR) is expressed in human skeletal muscle cells. Variations of CFTR dysfunction among patients with cystic fibrosis may be an important determinant of maximal exercise capacity in cystic fibrosis. Previous studies on the relationship between CFTR genotype and maximal exercise capacity are scarce and contradictory.

OBJECTIVES

This study was designed to explore factors influencing maximal exercise capacity, expressed as peak oxygen uptake (V.O2peak), with a specific focus on CFTR genotype in children and adults with cystic fibrosis.

METHODS

In an international, multicenter, cross-sectional study, we collected data on CFTR genotype and cardiopulmonary exercise tests in patients with cystic fibrosis who were ages 8 years and older. CFTR mutations were classified into functional classes I–V.

RESULTS

The final analysis included 726 patients (45% females; age range, 8–61 yr; forced expiratory volume in 1 s, 16 to 123% predicted) from 17 cystic fibrosis centers in North America, Europe, Australia, and Asia, all of whom had both valid maximal cardiopulmonary exercise tests and complete CFTR genotype data. Overall, patients exhibited exercise intolerance (V.O2peak, 77.3 ± 19.1% predicted), but values were comparable among different CFTR classes. We did not detect an association between CFTR genotype functional classes I–III and either V.O2peak (percent predicted) (adjusted β = −0.95; 95% CI, −4.18 to 2.29; P = 0.57) or maximum work rate (Wattmax) (adjusted β = −1.38; 95% CI, −5.04 to 2.27; P = 0.46) compared with classes IV–V. Those with at least one copy of a F508del-CFTR mutation and one copy of a class V mutation had a significantly lower V.O2peak (β = −8.24%; 95% CI, −14.53 to −2.99; P = 0.003) and lower Wattmax (adjusted β = −7.59%; 95% CI, −14.21 to −0.95; P = 0.025) than those with two copies of a class II mutation. On the basis of linear regression analysis adjusted for relevant confounders, lung function and body mass index were associated with V.O2peak.

CONCLUSIONS

CFTR functional genotype class was not associated with maximal exercise capacity in patients with cystic fibrosis overall, but those with at least one copy of a F508del-CFTR mutation and a single class V mutation had lower maximal exercise capacity.

Physiological markers of exercise capacity and lung disease severity in cystic fibrosis

BACKGROUND AND OBJECTIVE

Peak aerobic capacity (VO₂ peak) is an important outcome measure in cystic fibrosis (CF), but measurement is not widely available and can be influenced by patient motivation, pain and fatigue. Alternative markers of disease severity would be helpful. Neural respiratory drive, measured using parasternal intercostal muscle electromyography (EMGpara), reflects the load to capacity balance of the respiratory system and provides a composite measure of pulmonary function impairment in CF. The aim of the study was to investigate the relationship between exercise capacity, EMGpara and established measures of pulmonary function in clinically stable adult CF patients.

METHODS

Twenty CF patients (12 males, median (range) age: 22.3 (17.0-43.1) years) performed the 10-m incremental shuttle walk test (ISWT) maximally with contemporaneous measures of aerobic metabolism. EMGpara was recorded from second intercostal space at rest and normalized using peak electromyogram activity obtained during maximum respiratory manoeuvres and expressed as EMGpara%max (EMGpara expressed as a percentage of maximum).

RESULTS

VO₂ peak was strongly correlated with ISWT distance (r = 0.864, P < 0.0001). Lung gas transfer (T_L CO) % predicted was best correlated with VO₂ peak (r = 0.842, P < 0.0001) and ISWT distance (r = 0.788, P < 0.0001). EMGpara%max also correlated with VO₂ peak (-0.757, P < 0.0001), while the relationships between exercise outcome measures and forced expiratory volume in 1 s (FEV₁ ) % predicted and forced vital capacity (FVC) % predicted were less strong. A T_L CO% predicted of <70.5% was the strongest predictor of VO₂ peak <32 mL/min/kg (area under the curve (AUC): 0.96, 100% sensitivity, 83.3% specificity). ISWT distance and EMGpara%max also performed well, with other pulmonary function variables demonstrating poorer predictive ability.

CONCLUSION

T_L CO% predicted and EMGpara%max relate strongly to exercise performance markers in CF and may provide alternative predictors of lung disease progression.

Physiotherapy management of cystic fibrosis

For many years physiotherapy for cystic fibrosis (CF) was synonymous with a daily routine of postural drainage and percussion. Improved longevity and a desire for independence, together with a clearer understanding of the pathophysiology of the disease, has led to the development of many airway clearance techniques. The contribution of ‘chest’ physiotherapy remained unchallenged until recent times when lack of robust evidence and the presentation of asymptomic infants and adults led some physiotherapists to question this traditional approach. As survival increases into the fourth and fifth decade unique complications have evolved and physiotherapy management is challenged with nonrespiratory aspects of treatment. This review will consider the evidence for, and current practice of airway clearance, the value of exercise and the emerging problems of musculoskeletal complications and incontinence.

Exercise responses are related to structural lung damage in CF pulmonary disease

INTRODUCTION

Early detection of lung disease is a primary objective in monitoring patients with Cystic Fibrosis (CF); High-Resolution-Computed-Tomography (HRCT) assesses structural damage. Spirometry and cardiopulmonary exercise testing are used for functional evaluation of CF lung disease.

AIM

To evaluate the deterioration of exercise testing parameters over a 2-year period compared to the change of spirometry and HRCT parameters among CF patients.

METHODS

Twenty-eight CF patients were evaluated with HRCT, spirometry, and exercise testing; 15 had two assessments with an interval of 2 years. Correlation analyses between Bhalla score parameters and functional measures were performed.

RESULTS

Twenty-eight patients with CF (mean age 14.9 years, mean forced expiratory volume in 1 sec [FEV1 ] 83.2%) were evaluated. FEV1 was not found to change significantly in the 2-year period (P = 0.612). Both mean Bhalla score and mean peak oxygen consumption (VO2 peak %) deteriorated significantly (P = 0.014 and P = 0.026, respectively). VO2 peak and respiratory equivalents for O2 and CO2 at peak exercise were found to be significant predictors of Bhalla score (r = -0.477, P = 0.010; r = 0.461, P = 0.018; r = 0.402; P = 0.042, respectively). Anaerobic threshold was associated with changes in Bhalla score over the following 2 years.

CONCLUSIONS

Exercise testing is more sensitive than spirometry to detect structural changes in CF lungs. Pediatr Pulmonol. 2016; 51:914-920. © 2016 Wiley Periodicals, Inc.

[Impact of physical exercise in cystic fibrosis patients: A systematic review]

INTRODUCTION

Beneficial effects of physical exercise have been previously demonstrated in patients with chronic obstructive pulmonary disease. The aim of this systematic review was to summarize the evidence supporting physical exercise to improve on lung function, exercise capacity and quality of life in cystic fibrosis patients.

METHODS

Medline database was used to search clinical studies from 2000 to 2015. We also analyzed the bibliographic section of the included studies, in order to identify additional references.

RESULTS

A total of 17 studies were identified. A great disparity was found in the results of the different studies. No systematic benefit was found on lung function, exercise capacity or quality of life. No relationship between the type of program and the benefits achieved was observed.

CONCLUSIONS

Evidence that physical exercise benefits lung function, exercise capacity and quality of life in cystic fibrosis patient is inconsistent and evidence does not support a particular standardized program for all patients.

Relationship between lung function and Modified Shuttle Test performance in adult patients with cystic fibrosis: a cross-sectional, retrospective study

OBJECTIVES

To investigate the relationship between lung function and exercise capacity in adults with cystic fibrosis (CF), and to develop a CF-specific equation to predict Modified Shuttle Test (MST) performance from baseline data.

DESIGN

Cross-sectional, retrospective study.

SETTING

Adult CF centre.

PARTICIPANTS

One hundred and twenty-seven patients with CF [61 male; mean age 25 years (range 17 to 52 years), mean forced expiratory volume in 1second (FEV1) 56% predicted (range 15 to 124%)].

MAIN OUTCOME MEASURES

MST and FEV1.

RESULTS

Overall, a moderate-to-good relationship was found between lung function and MST performance (walking distance vs FEV1% predicted: r=0.64, P=0.01). This relationship between FEV1 and MST shows an obvious threshold at an FEV1 of 67% predicted. Above this threshold, no significant association was observed between FEV1 and MST performance. However, a strong relationship (MST vs FEV1% predicted: r≥0.74, P<0.01 for men and r=0.79, P<0.01 for women) was found below an FEV1 of 67% predicted.

CONCLUSIONS

This study suggests that a strong association exists between lung function (FEV1% predicted) and MST (walking distance) in adult patients with moderate-to-severe CF (FEV1<67% predicted). A reference equation for MST performance was developed for those patients with FEV1 ≤67% predicted, providing a tool to make an a-priori prediction of MST walking distance.

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 (VO_2peak), 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 (P_ETCO₂), and the VE to the work rate (VE/WR) ratio were examined. VO_2peak 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 P_ETCO₂ 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 P_ETCO₂ values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction.

Physiological correlates of pulmonary function in children with cystic fibrosis

RATIONALE

Although peak aerobic capacity (VO(2peak)) has been linked to outcome in patients with cystic fibrosis (CF), measuring is time consuming, and requires expensive equipment and expertise that is not readily available in all centers. Other fitness parameters such as peak anaerobic power, measures of power and strength may be simpler to deliver in the clinic. The relationship between these measures and established outcomes such as forced expiratory volume in one second (FEV(1)) and peak aerobic power (VO(2peak)) in CF remains unclear. Therefore we evaluated (a) aerobic fitness, (b) anaerobic fitness, and (c) upper and lower body muscle strength to determine their relationship to FEV(1) and VO(2peak) in children with CF.

METHODS

Eighty-two patients (7-18 years) with CF (40 female) from the CF clinic at The Hospital for Sick Children in Toronto performed a maximal incremental cycling test to exhaustion. Anaerobic power (W) for 10 and 30 sec cycling trials as well as vertical jump (VJ) and hand grip strength (HG) were compared to FEV(1) and VO(2peak).

RESULTS

Absolute VO(2peak) (R(2)  = 0.16, P < 0.001), anaerobic power (R(2)  = 0.21, P < 0.001), and hand grip strength (R(2)  = 0.10, P = 0.003) were significantly correlated to lung function whereas measures of explosive lower body strength (VJ) were not. Anaerobic power (R(2)  = 0.16, P = 0.001) and hand grip strength (R(2)  = 0.08, P = 0.01) were related to VO(2peak). Vertical jump was correlated with VO(2peak) (R(2)  = 0.29, P < 0.001) but not FEV(1).

CONCLUSIONS

Simple fitness tests such as hand grip strength and anaerobic cycle tests may be useful indicators of lung health and fitness.

Determinants of exercise capacity in cystic fibrosis patients with mild-to-moderate lung disease

Background

Adult patients with cystic fibrosis (CF) frequently have reduced exercise tolerance, which is multifactorial but mainly due to bronchial obstruction. The aim of this retrospective analysis was to determine the mechanisms responsible for exercise intolerance in patients with mild-to-moderate or severe disease.

Methods

Cardiopulmonary exercise testing with blood gas analysis at peak exercise was performed in 102 patients aged 28 ± 11 years: 48 patients had severe lung disease (FEV₁ < 50%, group 1) and 54 had mild-to-moderate lung disease (FEV₁ ≥ 50%, group 2). VO₂ peak was measured and correlated with clinical, biological, and functional parameters.

Results

VO₂ peak for all patients was 25 ± 9 mL/kg/min (65 ± 21% of the predicted value) and was < 84% of predicted in 82% of patients (100% of group 1, 65% of group 2). VO₂ peak was correlated with body mass index, C-reactive protein, FEV₁, FVC, RV, DLCO, V_E/VCO₂ peak, V_D/V_T, PaO₂, PaCO₂, P(A-a)O₂, and breathing reserve. In multivariate analysis, FEV₁ and overall hyperventilation during exercise were independent determinants of exercise capacity (R² = 0.67). FEV₁ was the major significant predictor of VO₂ peak impairment in group 1, accounting for 31% of VO₂ peak alteration, whereas excessive overall hyperventilation (reduced or absent breathing reserve and V_E/VCO₂) accounted for 41% of VO₂ alteration in group 2.

Conclusion

Exercise limitation in adult patients with CF is largely dependent on FEV₁ in patients with severe lung disease and on the magnitude of the ventilatory response to exercise in patients with mild-to-moderate lung disease.

Infection, inflammation and exercise in cystic fibrosis

Regular exercise is positively associated with health. It has also been suggested to exert anti-inflammatory effects. In healthy subjects, a single exercise session results in immune cell activation, which is characterized by production of immune modulatory peptides (e.g. IL-6, IL-8), a leukocytosis and enhanced immune cell functions. Upon cessation of exercise, immune activation is followed by a tolerizing phase, characterized by a reduced responsiveness of immune cells. Regular exercise of moderate intensity and duration has been shown to exert anti-inflammatory effects and is associated with a reduced disease incidence and viral infection susceptibility. Specific exercise programs may therefore be used to modify the course of chronic inflammatory and infectious diseases such as cystic fibrosis (CF).Patients with CF suffer from severe and chronic pulmonary infections and inflammation, leading to obstructive and restrictive pulmonary disease, exercise intolerance and muscle cachexia. Inflammation is characterized by a hyper-inflammatory phenotype. Patients are encouraged to engage in exercise programs to maintain physical fitness, quality of life, pulmonary function and health.In this review, we present an overview of available literature describing the association between regular exercise, inflammation and infection susceptibility and discuss the implications of these observations for prevention and treatment of inflammation and infection susceptibility in patients with CF.

The Impact of Pulmonary Arterial Pressure on Exercise Capacity in Mild-to-Moderate Cystic Fibrosis: A Case Control Study

Background. Pulmonary hypertension (PH) is an often complication of severe cystic fibrosis (CF); however, data on the presence and impact of pulmonary vasculopathy in adult CF patients with milder disease, is very limited. Aim. To investigate, for the first time, the impact of systolic pulmonary arterial pressure (PASP) on maximal exercise capacity in adults with mild-to-moderate cystic fibrosis, without PH at rest. Methods. This is a Case Control study. Seventeen adults with mild-to-moderate CF, without PH at rest (cases) and 10 healthy, nonsmoking, age, and height matched controls were studied. All subjects underwent maximal cardiopulmonary exercise testing and echocardiography before and within 1 minute after stopping exercise. Results. Exercise ventilation parameters were similar in the two groups; however, cases, compared to controls, had higher postexercise PASP and decreased exercise capacity, established with lower peak work rate, peak O(2) uptake, anaerobic threshold, and peak O(2) pulse. Furthermore, the change in PASP values before and after exercise was strongly correlated to the parameters of exercise capacity among cases but not among controls. Conclusions. CF adults with mild-to-moderate disease should be screened for the presence of pulmonary vasculopathy, since the elevation of PASP during exercise might contribute to impaired exercise capacity.

Exercise Capacity in Prepubertal Children with Cystic Fibrosis

Background. Patients with cystic fibrosis (CF) are observed to have diminished lung function, nutritional status, and aerobic exercise capacity. All three parameters are related to prognosis and survival. However, there is little information regarding these parameters in prepubertal patients. Methods. Our study groups consisted of sixteen patients with CF (7 girls) and 99 healthy volunteers (52 girls). Subjects performed spirometry and a progressive exercise test to exhaustion on a cycle ergometer. Leg muscle strength was measured using an isokinetic dynamometer. Physical activity was examined using the modifiable activity questionnaire and accelerometer. Results. Nutritional status was similar between groups (BMI—boys control versus CF 18.5 versus 17.9, girls control versus CF 19.5 versus 17.4). Girls with CF were significantly smaller and lighter than controls. Lung function was significantly reduced in CF groups (FEV1—boys control versus CF 91% versus 84%, girls control versus CF 90% versus 82%). Patients with CF were as active and as fit as their healthy controls. Conclusion. In this group of prepubertal children with CF, nutritional status was comparable to healthy children of the same age. Their aerobic exercise tolerance and peripheral muscle strength were also relatively well preserved despite significantly lower lung function.

Is static hyperinflation a limiting factor during exercise in adolescents with cystic fibrosis?

Increased work of breathing is considered to be a limiting factor in patients with cystic fibrosis (CF) performing aerobic exercise. We hypothesized that adolescents with CF and with static hyperinflation are more prone to a ventilatorily limited exercise capacity than non-static hyperinflated adolescents with CF. Exercise data of 119 adolescents with CF [range 12-18 years], stratified for static hyperinflation, defined as ratio of residual volume to total lung capacity (RV/TLC) > 30%, were obtained during a progressive bicycle ergometer test with gas analysis and analyzed for ventilatory limitation. Static hyperinflation showed a significant, though weak association (Φ 0.38; P < 0.001) with a ventilatorily limited exercise capacity (breathing reserve index at maximal effort >0.70; FEV(1)  < 80% predicted and reduced exercise capacity, defined as VO(2peak)  < 85% predicted). Analysis of association for increasing degrees of hyperinflation showed an increase to Φ 0.49 (P < 0.001) for RV/TLC > 50%. In adolescents with static hyperinflation, peak work rate (W(peak) ; 3.1 ± 0.7 W/kg (75.1 ± 17.3% of predicted), peak oxygen uptake (VO(2peak) /kg (ml/min/kg); 39.2 ± 9.2 ml/min/kg (91.0 ± 20.3% of predicted), peak heart rate (HR(peak) ; 176 ± 19 beats/min) were significantly (P < 0.05) decreased when compared with non-static hyperinflated adolescents (W(peak) 3.5 ± 0.5 W/kg (81.4 ± 10.0% of predicted)); VO(2peak) /kg (ml/min/kg); 43.1 ± 7.5 ml/min/kg (98.0 ± 15.1% of predicted); and HR(peak) 185 ± 14 beats/min). Additionally, no difference was found in the degree of association of FEV(1) (%) and RV/TLC (%) with VO(2peak) /kg(pred) and W(peak) /kg(Pred) , but we found the RV/TLC (%) to be a slightly stronger predictor of VO(2peak) /kg(pred) and W(peak) /kg(Pred) than FEV(1) (%). These results indicate that the presence of static hyperinflation in adolescents with CF by itself does not strongly influence ventilatory constraints during exercise and that static hyperinflation is only a slightly stronger predictor of W(peak) /kg(Pred) and VO(2peak) /kg(Pred) than airflow obstruction (FEV(1) (%)).

Skeletal muscle metabolism in cystic fibrosis and primary ciliary dyskinesia

Previous studies have reported differences in muscle function and metabolism between patients with cystic fibrosis (CF) and healthy controls (HC), but it is currently unknown whether these abnormalities are specific to CF or also seen in other airway diseases. In this study, we used magnetic resonance spectroscopy (MRS) during exercise to assess muscle metabolism in CF patients. Twenty patients with CF and 20 age, gender, and habitual activity-matched HCs and a respiratory disease comparison group with primary ciliary dyskinesia (PCD; n = 10) were studied. Phosphorus MRS (P-MRS) was used to characterize muscle bioenergetic metabolism at rest and after high-, moderate-, and low-intensity exercise. CF patients exhibited lower resting ATP/phosphocreatine (PCr) ratio and significantly higher end-exercise pH values compared with both HC and PCD patients. Both CF and PCD patients demonstrated significantly slower PCr recovery time constants after high-intensity exercise. Our results suggest that not only there are specific abnormalities of muscle metabolism in CF patients but also there is a nonspecific impact of respiratory disease on muscle function.

Supramaximal verification of peak oxygen uptake in adolescents with cystic fibrosis

PURPOSE

To study whether peak oxygen uptake ((Equation is included in full-text article VO₂ peak), attained in traditional cardiopulmonary exercise testing (CPET) in adolescents with cystic fibrosis (CF), could be verified by a supramaximal exercise test.

METHODS

Sixteen adolescents with CF (forced expiratory volume in 1 second as % of predicted [range, 45%-117%]) volunteered and successively performed CPET and a supramaximal test (Steep Ramp Test [SRT] protocol).

RESULTS

Cardiopulmonary exercise testing and the SRT resulted in comparable cardiorespiratory peak values. We found no significant difference in oxygen uptake ((Equation is included in full-text article VO₂ peak/kg) between CPET and the SRT (38.9 ± 7.4 and 38.8 ± 8.5 mL min kg, respectively; P = .81). We found no systemic bias for CPET and SRT measurements of (Equation is included in full-text article VO₂  peak/kg and no differences between CPET and SRT (Equation is included in full-text article VO₂  peak values within and between the maximal and non-maximal effort groups (P > .4).

CONCLUSION

The (Equation is included in full-text article VO₂  peak measured in CPET seems to reflect the true (Equation is included in full-text article.)O2 peak in adolescents with CF.

Exercise training in children and adolescents with cystic fibrosis: theory into practice

Physical activity and exercise training play an important role in the clinical management of patients with cystic fibrosis (CF). Exercise training is more common and recognized as an essential part of rehabilitation programmes and overall CF care. Regular exercise training is associated with improved aerobic and anaerobic capacity, higher pulmonary function, and enhanced airway mucus clearance. Furthermore, patients with higher aerobic fitness have an improved survival. Aerobic and anaerobic training may have different effects, while the combination of both have been reported to be beneficial in CF. However, exercise training remains underutilised and not always incorporated into routine CF management. We provide an update on aerobic and anaerobic responses to exercise and general training recommendations in children and adolescents with CF. We propose that an active lifestyle and exercise training are an efficacious part of regular CF patient management.

Exercise and physical activity in children with cystic fibrosis

Regular exercise and habitual physical activity are important for patients with cystic fibrosis (CF). Research has demonstrated the benefits of aerobic, anaerobic, and strength exercise training programs for health and quality of life, however, the CF patient is faced with unique barriers and challenges to participation. Recently, increased levels of habitual physical activity have been shown to slow the decline in lung function in patients with CF, and regular participation in a variety of activities may result in greater adherence in the long term. Research is now available to justify the incorporation of exercise into the routine care of patients with CF. This paper provides the background and rationale for the implementation of exercise and habitual physical activity recommendations by the health care team. Education of health care providers regarding the importance of exercise and habitual physical activity for patients with CF is needed in order for exercise and physical activity to be incorporated as key components of clinical practice and into the lives of patients with CF.

Substrate utilization during and after exercise in mild cystic fibrosis

PURPOSE

To determine substrate utilization and energy expenditure during maximal and submaximal exercise and recovery in adolescents with cystic fibrosis (CF) and healthy age-matched controls (C).

METHODS

Ten clinically stable CF patients (four girls, six boys; age = 10-22 yr) were matched by body mass index, age, gender, and Tanner stage to healthy controls. Subjects completed VO(2peak) testing and submaximal exercise (20 min) on a cycle ergometer at a relative intensity of 50% VO2(peak) and at an absolute power output (PO). Metabolic parameters were assessed during exercise and recovery (20 min).

RESULTS

Similar respiratory quotient (RQ) values occurred in both groups during maximal exercise and recovery, despite differences in the maximal PO [CF = 114 (60-180) W and C = 171 (105-280) W, P = 0.006], the total work completed [CF = 27 (9.0-54.3) kJ and C = 55 (25.3-126.5) kJ, P = 0.008], or the VO(2peak) value attained [CF = 30.6 (8.5-45.2) mL kg(-1) min(-1) and C = 40.6 (29-64.5) mL kg(-1) min(-1), P = 0.027]. Submaximal exercise at the same absolute PO resulted in similar RQ values during exercise and recovery despite higher heart rates and average VO2 [CF = 18.8 (9.3-28.7) mL kg(-1) min(-1) and C = 15.2 (6.5-20.1) mL kg(-1)min(-1), P = 0.031] values in CF adolescents, and submaximal exercise at the same relative intensity also resulted in similar RQ values despite significantly greater average PO in the C group [CF = 38.7 (12.3-80) W and C = 67.8 (25.5-140) W, P = 0.039]. Excess postexercise oxygen consumption (EPOC) was greater in CF [2.79 (1.14-5.24) L O2] than C [1.46 (0.56-2.80) L O2] after submaximal exercise at a fixed PO (P = 0.036) but not after the relative exercise bout.

CONCLUSIONS

Habitual physical activity participation does not warrant adjustment of macronutrient intake ratios in adolescents with mild to moderate CF, but total caloric intake may need to be increased based on the level of EPOC and upon the intensity and the duration of the habitual activity.

Early oxygen uptake recovery following exercise testing in children with chronic chest diseases

The value of exercise testing as an objective measure of disease severity in patients with chronic chest diseases (CCD) is becoming increasingly recognized. The aim of this study was to investigate changes in oxygen uptake (VO2) during early recovery following maximal cardiopulmonary exercise testing (CPXT) in relation to functional capacity and markers of disease severity. Twenty-seven children with CCD (age 12.7 +/- 3.1 years; 17 female) [19 children with Cystic fibrosis (CF) (age 13.4 +/- 3.1 years; 10 female) and 8 with other stable non-CF chest diseases (NON-CF) (age 11.1 +/- 2.2 years; 7 female)] and 27 healthy controls (age 13.2 +/- 3.3 years; 17 female) underwent CPXT on a cycle ergometer. On-line respiratory gas analysis measured VO2 before and during CPXT to peak VO2) (VO2(peak)), and during the first 10 min of recovery. Early VO2 recovery was quantified by the time (sec) to reach 50% of the VO2 (peak) value. Early VO2 recovery was correlated against spirometry [forced expiratory volume in 1 sec (FEV(1)) and forced expiratory flow between 25% and 75% of the forced vital capacity (FEF(25-75))] and aerobic fitness (VO2)(peak)) as a measure of functional capacity. Disease severity was graded in the CF patients by the Shwachman score (SS). Compared to controls, children with CCD demonstrated a significantly reduced VO2(peak) (P = 0.011), FEV(1) (P < 0.001), FEF(25-75) (P < 0.001), and a significantly prolonged early (VO2) recovery (P = 0.024). In the CF patients the SS was significantly correlated with early VO2 recovery (r = -0.63, P = 0.004), FEV(1) (r = 0.72, P = 0.001), and FEF(25-75) (r = 0.57, P = 0.011). In the children with CCD, FEV(1), FEF(25-75), and BMI were not significantly correlated with VO2(peak) or early VO2 recovery. Lung function does not necessarily reflect aerobic fitness and the ability to recover from exercise in these patients. A significant relationship was found between VO2(peak) and early VO2 recovery (r = -0.39, P = 0.044) in the children with CCD, showing that a greater aerobic fitness corresponded with a faster recovery.

Clinical exercise testing in children and adolescents with cystic fibrosis

PURPOSE

To review the most common field and laboratory exercise tests available for children and adolescents with cystic fibrosis (CF).

METHODS

Relevant studies for this review were identified by electronic search of Medline and PubMed databases between the years 1958 and 2008. The bibliographies of all accessed publications were also searched. Key descriptors were cystic fibrosis, exercise testing, aerobic fitness, children, and adolescents.

RESULTS

Five field tests were selected for presentation, including discussion of their strengths and weaknesses. Laboratory tests measuring aerobic and anaerobic responses to exercise in children with CF were also selected for presentation and discussed along with a summary of safety considerations for exercise testing of children with CF.

CONCLUSION

Exercise testing is regarded an important prognostic tool in CF care. However, despite its beneficial effects, clinical exercise testing seems underused. Clinicians and their staff should encourage patients with CF to be physically active and recommend exercise testing annually.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Effect of Albuterol on Maximal Exercise Capacity in Cystic Fibrosis

BACKGROUND

Inhaled, short-acting beta-adrenergic agonists (SAbetaAs) are widely prescribed in cystic fibrosis (CF) subjects, despite a lack of convincing data for efficacy and the potential for these agents to result in airway instability. We tested the hypothesis that inhaled albuterol would improve maximal exercise performance in CF subjects with airflow obstruction, as a result of acute bronchodilation.

METHODS

Randomized, double-blind, placebo-controlled crossover study of the effect of inhaled albuterol on maximal exercise performance in 20 stable adult CF patients (mean +/- SD age, 23.3 +/- 6.1 years; FEV(1), 57.65 +/- 17.13% of predicted).

RESULTS

Ventilatory limitation to exercise was demonstrated in 16 subjects (80%). Significant bronchodilation occurred with exercise alone (end-exercise FEV(1), 2.24 +/- 0.8 L; vs preexercise FEV(1), 2.09 +/- 0.77 L; p < 0.0001), but albuterol resulted in significantly greater exercise-induced bronchodilation than placebo (change in FEV(1), 0.3 +/- 0.15 L vs 0.15 +/- 0.11 L; 95% confidence interval [CI], + 0.07 to + 0.23; p < 0.001). However, there was no difference in maximal workload achieved (albuterol, 158 +/- 46 W; vs placebo, 158 +/- 45 W; 95% CI, - 4.41 to + 4.71; p = 0.95), nor any other measure of exercise performance including maximal oxygen uptake.

CONCLUSIONS

Despite causing significant acute bronchodilation, inhaled albuterol did not improve maximal exercise performance in ventilatory-limited CF adults, adding to the body of literature that fails to show any clinical benefit of SAbetaAs in CF subjects. The current results provide further evidence to question the widespread use of these agents, although the potential for adrenergic beta-agonists to instead improve submaximal exercise performance merits further investigation.

Timing and driving components of the breathing strategy in children with cystic fibrosis during exercise

The aim of this study was twofold: first, to determine the breathing strategies of children with cystic fibrosis (CF) during exercise, and secondly, to see if there was a correlation with lung function parameters. We determined the tension-time index of the inspiratory muscles (T(T0.1)) during exercise in nine children with CF, who were compared with nine healthy children with a similar age distribution. T(T0.1) was determined as followed T(T0.1) = P0.1/PImax . T(I)/T(TOT), where P0.1 is mouth occlusion pressure, PImax is maximal inspiratory pressure, and T(I)/T(TOT) is the duty cycle. CF children showed a significant decrease of their forced expiratory volume in 1 sec (FEV1), forced vital capacity (FCV), and FEV1/FVC, whereas the residual volume to total lung capacity ratio (RV/TLC) ratio and functional residual capacity (FRC) were significantly increased (P < 0.001). Children with CF showed mild malnutrition assessed by actual weight expressed by percentage of ideal weight for height, age, and gender (weight/height ratio; 82.3 +/- 3.6%). Children with CF showed a significant reduction in their PImax (69.3 +/- 4.2 vs. 93.8 +/- 7 cmH2O). We found a negative linear correlation between PImax and weight/height only in children with CF (r = 0.9, P < 0.001). During exercise, P(0.1), P0.1/PImax, and T(T0.1) were significantly higher, for a same percent maximal oxygen uptake in children with CF. On the contrary, T(I)/T(TOT) ratio was significantly lower in children with CF compared with healthy children. At maximal exercise, children with CF showed a T(T0.1) = 0.16 vs. 0.14 in healthy children (P < 0.001). We observed at maximal exercise that P0.1/PImax increased as FEV1/FVC decreased (r = -0.90, P < 0.001), and increased as RV/TLC increased (r = 0.92, P < 0.001) only in children with CF. Inversely, T(I)/T(TOT) decreased as FEV1/FVC decreased (r = 0.89, P < 0.001), and T(I)/T(TOT) decreased as RV/TLC increased (r = -0.94, P < 0.001). These results suggest that children with CF adopted a breathing strategy during exercise in limiting the increase of the duty cycle. Two determinants of this strategy were degrees of airway obstruction and hyperinflation.

Effects of Anaerobic Training in Children With Cystic Fibrosis

BACKGROUND

Children's physical activity patterns are characterized by short-term anaerobic activities. Anaerobic exercise performance in children with cystic fibrosis (CF) has received little attention compared to aerobic performance. This study investigated the effects of anaerobic training in children with CF.

DESIGN AND METHODS

Twenty patients were randomly assigned to the training group (TG) [11 patients; mean (+/- SD) age, 13.6 +/- 1.3 years; mean FEV(1), 75.2 +/- 20.7% predicted] or the control group (CG) [9 patients; mean age, 14.2 +/- 2.1 years; FEV(1), 82.1 +/- 19.1% predicted]. The TG trained 2 days per week for 12 weeks, with each session lasting 30 to 45 min. The training program consisted of anaerobic activities lasting 20 to 30 s. The control subjects were asked not to change their normal daily activities. Body composition, pulmonary function, peripheral muscle force, habitual physical activity, aerobic and anaerobic exercise performance, and quality of life were reevaluated at the end of the training program, and again after a 12-week follow-up period.

RESULTS

Patients in the TG significantly improved their anaerobic performance, aerobic performance, and quality of life. No significant changes were seen in other parameters, and no improvements were found in CG. After the follow-up period, only anaerobic performance and quality of life in TG were significantly higher compared to pretraining values.

CONCLUSIONS

Anaerobic training has measurable effects on aerobic performance (although not sustained), anaerobic performance, and health-related quality of life in children with CF. Therefore, anaerobic training could be an important component of therapeutic programs for CF patients.

Growth hormone and exercise tolerance in patients with cystic fibrosis

Cystic fibrosis (CF) is a life-limiting inherited disorder characterised by pulmonary disease, pancreatic dysfunction and symptoms of malnutrition that are all interrelated with low exercise capacity and poor survival rate. Therapy with growth hormone (GH) may improve the reduced dimensional and functional capacity associated with poor nutritional status and catabolism and therefore improve exercise tolerance, quality of life and survival rate in patients with CF. The literature about GH treatment and its effect on exercise tolerance are rather limited, not always consistent and methodological concerns restrict further analysis. GH treatment may have beneficial effects on both growth and exercise tolerance without serious complications in prepubertal children with CF. The observed dimensional changes of the muscular, cardiovascular and pulmonary system seem to improve aerobic exercise capacity and respiratory and peripheral muscle strength. The physiological background of the observed changes is not yet fully understood, therefore, larger-scale studies with an optimised design are required.

Longitudinal Determinants of Peak Aerobic Performance in Children With Cystic Fibrosis

BACKGROUND

Several cross-sectional studies in patients with cystic fibrosis (CF) have shown that nutritional status and lung function are important determinants of peak aerobic capacity (peak oxygen uptake [O(2)peak]). In order to account for individual changes, the aim of this study was to determine the longitudinal relationship of changes in nutritional status, lung function, and O(2)peak in children with CF.

DESIGN AND METHODS

Fat-free mass (FFM), lung function, and O(2)peak were assessed in 65 children with CF at baseline (mean +/- SD age, 10.5 +/- 2.9 years; mean FEV(1), 92.6 +/- 20.5%) and again 2 years later. FFM was calculated using skinfold thickness, and O(2)peak was measured using an incremental treadmill test for children < 12 years old or an incremental cycle ergometry test for children > or =12 years old. Lung function was measured before the exercise test.

RESULTS

Over the 2-year study period, an increase was found for absolute values of FFM (6.1 kg, p < 0.001), FEV(1) (229 mL, p < 0.001), and O(2)peak (240 mL, p < 0.001), while a decrease was found for predicted values of FEV(1) (- 8.9%, p < 0.001) and O(2)peak (- 4.4%, p < 0.05). DeltaO(2)peak over the 2-year period best correlated with DeltaFEV(1) (r = 0.619, p < 0.001) and to a lesser degree with DeltaFFM (r = 0.506, p < 0.001). Multiple regression analysis demonstrated that DeltaFEV(1) and DeltaFFM explained 47% of the variation of the DeltaO(2)peak over the 2-year period.

CONCLUSIONS

Our results show that longitudinal changes in O(2)peak are associated with changes in lung function and to a lesser extent with changes in nutritional status in children with CF. Special consideration should be given to exercise training and nutritional intervention, which might improve long-term clinical outcome in children with CF.

Anaerobic exercise in pediatric cystic fibrosis

Anaerobic fitness is important for daily functioning of children with cystic fibrosis (CF). The aim of this study was to assess the determinants of anaerobic performance in CF. Anaerobic performance was measured in 39 children with CF (mean age, 13.2 +/- 1.8 (SD) years, forced expired volume in 1 sec (FEV(1)) 81.6 +/- 22.1% predicted), using a Wingate anaerobic test. Significant associations were found for peak power (PP) and mean power (MP) with fat-free mass (FFM) body weight, body mass index, maximal isometric muscle force, and aerobic capacity. Pulmonary function was correlated with anaerobic indices when controlled for FFM. Multiple regression analysis indicated that FFM and FEV(1) accounted for 82% and 86% of the variability in PP and MP, respectively. Patients with moderate CF (FEV(1) < 80%), as compared to mild CF (FEV(1) >/= 80%), had higher PP (difference = 85 W, 95% CI = 27-144 W) and MP (difference = 53 W, 95% CI = 42-63 W) at equivalent FFM. Our results indicate that FFM and pulmonary function are important determinants of anaerobic exercise performance in children with CF. With progression of pulmonary disease, anaerobic performance may be enhanced.

An elevated breathing reserve index at the lactate threshold is a predictor of mortality in patients with cystic fibrosis awaiting lung transplantation

The proportion of cystic fibrosis (CF) patients dying while on the lung transplant wait list remains high; identification of such patients remains difficult. The breathing reserve index (BRI = minute ventilation/maximal voluntary ventilation) at the lactate threshold (LT) is a predictor of a pulmonary mechanical limit to incremental exercise. We hypothesized that an elevated BRI at the LT in patients with CF awaiting lung transplantation would be a predictor of wait list mortality. Forty-five consecutive patients with CF completed cardiopulmonary exercise testing as part of their pretransplant assessment. We evaluated BRI at LT, baseline demographic characteristics, pulmonary function, and other exercise parameters via Cox proportional hazards modeling. Fifteen patients died while awaiting transplant. Twenty one were transplanted, and nine still awaited transplantation. Relative risks from the multivariate model included (95% confidence interval in parentheses) BRI at LT, 17.52 (2.45-123.97); resting Pa(CO(2)), 1.29 (1.10-1.49); resting Pa(O(2)), 0.97 (0.90-1.05); and forced expiratory volume at one second as a percent of predicted, 1.19 (1.05-1.34). BRI at LT not only provided the highest point estimate of risk for wait list mortality but also identified a physiologically significant threshold value (0.70 or more) for those at risk. This measurement may allow improved timing of listing for transplantation, including consideration for living donor transplantation.