Exercise testing in cystic fibrosis: Who and why?

Six-minute walk test and factors affecting exercise capacity in children with cystic fibrosis

PURPOSE

This study aimed to compare the result of the six-minute walk test (6MWT) in patients with cystic fibrosis (CF) aged < 20 years old and individuals without CF.

METHODS

In this cross-sectional study, 50 children and adolescents with CF and 20 children and adolescents without CF underwent the 6MWT. Vital signs before and immediately after the 6MWT and six-minute walk distance (6MWD) were evaluated.

RESULTS

The mean change in heart rate, percentage of peripheral oxygen saturation (SpO2%), systolic blood pressure, respiratory rate, and dyspnea severity during the 6MWT was significantly higher in patients with CF. In the case group, 6MWD was associated with regular chest physical therapy (CPT) and forced expiratory volume (FEV)> 80%. Patients with CF receiving regular CPT or mechanical vibration and with FEV in the first second > 80% showed better physical capacity during the 6MWT (smaller Sp02% decline and lower dyspnea perception).

CONCLUSION

Children and adolescents with CF have lower physical capacity compared to individuals without CF. CPT and mechanical vibration could be used to increase physical capacity in this population.

Feasibility of the A-STEP for the assessment of exercise capacity in people with cystic fibrosis

OBJECTIVES

To evaluate feasibility of the Alfred Step Test Exercise Protocol (A-STEP) for the assessment of exercise capacity in adults and children with cystic fibrosis (CF); in adults to test whether demographics and/or lung function correlated with exercise capacity.

METHODS

Adults and children with stable CF from two centres completed the A-STEP (a recently developed incremental maximal-effort step test). Feasibility was evaluated by: usefulness for exercise capacity assessment (measures of exercise capacity were: level reached, exercise-induced desaturation, and achievement of at least one maximal effort criteria); safety; operational factors; time to complete; floor and/or ceiling effects. We used multiple linear regression to test whether demographics and/or lung function correlated with exercise capacity.

RESULTS

A total of 49 participants: 38 adults (18 male), percent predicted (pp) forced expiration in one second (FEV₁ ) 29-109, aged 22-48 years and 11 children (6 male), ppFEV₁ 68-107, aged 10-15 years were included. Levels reached (mean (SD) [range]) were 10.2 (2.4) [6-15] (adults), 10.1 (2.5) [7-14] (children); desaturation (change between baseline and peak-exercise SpO₂ ): was 8.4 (3.8 [0-15]% (adults), 2.0 (2.0) [0-7]% (children). A total of 8 (21%) adults and no children desaturated <90% SpO₂ . At least one criterion for maximal effort was reached by 33 (84%) adults and 10 (91%) children. There were no adverse events. The A-STEP was straightforward to use and carried out by one operator. A total of 26 (68.4%) adults and 7 (63.6%) children completed the test within the recommended 8-12 min. All participants completed a minimum of 6 levels, and completed the test before the final 16th level. In adults, ppFEV₁ and ppFVC correlated with the level reached (r = 0.55; p = <0.001 and r = 0.66, p = <0.0001) and desaturation (r = 0.55, p = <0.001 and r = 0.45, p = <0.005).

CONCLUSION

In adults and children with stable CF, the A-STEP was feasible, safe, and operationally easy to use for the assessment of exercise capacity, without floor or ceiling effects. In adults, lung function correlated with exercise capacity.

Exercise testing and exercise training within cystic fibrosis centres across Australia and New Zealand: what is considered important and what is current practice?

BACKGROUND

Within Australian and New Zealand cystic fibrosis (CF) centres, exercise testing and exercise training are common components of clinical care, but current practices regarding these components have not been reported.

AIM

To determine the extent, scope and importance placed on exercise testing and exercise training within CF centres across Australia and New Zealand.

METHODS

Information pertaining to exercise testing and training practices was sought by administering a survey to health professionals working in CF centres across Australia and New Zealand. The survey comprised five sections (46 questions) and was sent via an online link (Qualtrics). Response rate was optimised using the Dillman approach. Approval for this study was granted from the Human Research Ethics Committee at Curtin University (HRE2018-074). Completion of the survey was taken as informed consent.

RESULTS

A response rate of 80% (n = 32/40) was achieved. Each state/territory in Australia, except the Northern Territory was represented in the survey responses. Eight of the 12 major regions in New Zealand were also represented. Regarding tests of exercise capacity, field-based tests were performed more commonly than laboratory-based tests (n = 28/32; 88% vs n = 11/32 centres; 34%; difference: 54%; 95% confidence interval 31-70%). Most (89%) respondents perceived field tests to be at least 'somewhat' important, whereas 91% of respondents perceived laboratory tests to be 'a little' to 'somewhat' important. Physical activity and/or exercise were discussed by at least one health professional in the CF team at every clinic appointment and/or annual review. Most centred offered outpatient exercise training each year to their patients (n = 24/32; 75%).

CONCLUSION

This survey captures the current practices of exercise testing and training in CF centres across Australia and New Zealand.

Adherence and barriers to general and respiratory exercises in cystic fibrosis

OBJECTIVES

To investigate the adherence and the self-reported barriers to general and respiratory exercises reported by individuals with cystic fibrosis (CF).

STUDY DESIGN

An exploratory, experimental study.

METHODS

Community-dwelling individuals aged 16 years and over, diagnosed with CF, who were accompanied in referral centers were included. Information regarding adherence to exercises was obtained by a questionnaire and reported as a ratio between prescribed exercises and self-reported adherence. The weekly frequency was used to verify adherence to exercise initiation, and the amount of session duration concluded was used to verify adherence to exercise duration. Values above 0.70 were considered as high adherence. Eight demographic and clinical factors were examined to explore their relationships with adherence, and the barriers to exercises were also collected by questionnaire.

RESULTS

Thirty-four participants met the inclusion criteria. Overall, adherence to exercise initiation was 0.40 (standard deviation [SD] = 0.3) for general exercises and 0.63 (SD = 0.4) for respiratory exercises. Adherence to exercise duration was 0.76 (SD = 0.4) for general exercises and 0.73 (SD = 0.4) for respiratory exercises. Forced vital capacity (r = 0.39; P = .02) was associated with adherence to the duration of general exercises, and body mass index (r = -0.33; P = .05) was associated with adherence to the duration of respiratory exercises. The main reported barriers were lack of interest, motivation and time, tiredness, noncommitment, and do not recognize the benefits of exercises.

CONCLUSIONS

Individuals with CF minded completing the sessions of prescribed exercises once they have initiated it, but most of the days they did not practice general or respiratory exercises.

Tissue oxygenation in peripheral muscles and functional capacity in cystic fibrosis: a cross-sectional study

NEW FINDINGS

What is the central question of this study? How do peripheral muscle tissue oxygenation and physical conditioning levels of children and adolescents with cystic fibrosis compare to demographically matched controls? What is the main finding and its importance? Children and adolescents with cystic fibrosis consumed more oxygen, more quickly and exhibited slower recovery, demonstrating that there may have been deficiencies in oxygen supply related to both oxygen uptake and oxygen transport.

ABSTRACT

Cystic fibrosis affects skeletal muscle performance and functional capacity. However, it is currently unclear how peripheral muscle behaviour is affected, especially in children and adolescents. To examine this, we compared tissue oxygenation of children and adolescents with cystic fibrosis against healthy volunteers. We also evaluated the functional capacity of participants via the modified shuttle test (MST) and assessed for associations between performance and near-infrared spectroscopy. A total of 124 participants enrolled. Participants were divided into either the cystic fibrosis group (CFG) or the healthy group (HG). Statistical comparisons between groups were evaluated with the Mann-Whitney U test and associations with functional capacity were evaluated using Spearman's correlation coefficient. CFG volunteers scored lower on the MST compared to the HG. They walked shorter distances (P = 0.001) with less efficiency because they performed the tests with a less efficient walking economy (P = 0.001) and a greater deoxyhaemoglobin concentration (P = 0.001). Further, they experienced reduced tissue oxygen saturation (P = 0.037) faster than the HG. As a result, they presented lower respiratory (P = 0.001) and lower heart (P = 0.001) rate values at the end of the MST, with a longer post-test heart rate recovery time (P = 0.005). There was a significant association between deoxygenation time and functional capacity. The CFG consumed more oxygen, more quickly, with a slower recovery, reflecting impairments in the dynamics of muscle oxygen extraction. The results suggest differences in functional capacity and haemodynamic recovery in children and adolescents with cystic fibrosis.

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

BACKGROUND

Severe scoliosis can affect respiratory function in growing patients and produce cardiopulmonary complications, leading to significant morbidity. The development of spinal deformity may impact on young patients' level of function and reported quality of life (QOL). The aim of this study was to investigate the relationship between lung function, exercise capacity and quality of life in young patients with spinal deformity.

METHODS

This is a retrospective analysis of 104 patients (31% male, 69% female with mean age 14.9yrs). 77% of patients had an adolescent idiopathic scoliosis, with the remainder having other scoliosis diagnoses or Scheuermann's kyphosis. Principal outcomes included Spirometry [FEV₁, FVC], Whole Body Plethysmography, Cardiopulmonary Exercise Testing [CPET] and patient outcome questionnaires (with SRS-22). CPET measures included maximal exercise capacity [VO_2peak] as well as VO₂ at ventilatory threshold [VT] expressed as %predicted VO_2max-a measure of physical conditioning, and minute ventilation [V_E] from which breathing reserve [BR] could be calculated.

RESULTS

Mean (±SD) main thoracic scoliosis was 59.9⁰ (±15.2⁰), and mean kyphosis in those with Scheuermann's condition was 95.3⁰ (±11.5⁰). No correlation was elicited between FEV₁ or FVC (%predicted) and VO_2peak (%predicted) in this patient cohort. Greater thoracic curves were associated with lower FEV₁ (%predicted), r = -0.343, p = 0.001, FVC (%predicted), r = -0.307, p = 0.003 and BR (%) at the end of exercise (r = -0.-0.459, p < 0.001). The patient cohort had a mean (sd) VO₂peak of 98(17) %predicted, with greater VO₂peak levels recorded in female subjects, those of younger age and those with higher scoliosis angles. Those with better lung function [FEV₁ (%predicted)] had better BR (%) at the end of exercise (r = 0.483, p < 0.001). SRS-22 scores correlated significantly with VO_2peak (%predicted) (total SRS-22 versus VO_2peak (%predicted), r = 0.336, p = 0.002).

CONCLUSION

Larger thoracic scoliotic curves are associated with poorer lung function but better exercise capacity, likely related to higher levels of physical conditioning. Higher QOL scores were recorded in patients who had greater VO_2peak levels, suggesting that exercise capacity may be a protective factor for emotional well-being in patients with spinal deformity.

Exercise Physiology Across the Lifespan in Cystic Fibrosis

Cystic fibrosis (CF), a severe life-limiting disease, is associated with multi-organ pathologies that contribute to a reduced exercise capacity. At present, the impact of, and interaction between, disease progression and other age-related physiological changes in CF on exercise capacity from child- to adult-hood is poorly understood. Indeed, the influences of disease progression and aging are inherently linked, leading to increasingly complex interactions. Thus, when interpreting age-related differences in exercise tolerance and devising exercise-based therapies for those with CF, it is critical to consider age-specific factors. Specifically, changes in lung function, chronic airway colonization by increasingly pathogenic and drug-resistant bacteria, the frequency and severity of pulmonary exacerbations, endocrine comorbidities, nutrition-related factors, and CFTR (cystic fibrosis transmembrane conductance regulator protein) modulator therapy, duration, and age of onset are important to consider. Accounting for how these factors ultimately influence the ability to exercise is central to understanding exercise impairments in individuals with CF, especially as the expected lifespan with CF continues to increase with advancements in therapies. Further studies are required that account for these factors and the changing landscape of CF in order to better understand how the evolution of CF disease impacts exercise (in)tolerance across the lifespan and thereby identify appropriate intervention targets and strategies.