Resting energy expenditure in children at risk of hypothalamic dysfunction.

Objective: Children with suprasellar brain damage are at risk of hypothalamic dysfunction (HD). HD may lead to decreased resting energy expenditure (REE). Decreased REE, however, is not present in all children with HD. Our aim was to assess which children suspect for HD have low REE, and its association with clinical severity of HD or radiological hypothalamic damage. Patients and methods: A retrospective cohort study was performed. Measured REE (mREE) of children at risk of HD was compared to predicted REE (pREE). Low REE was defined as mREE <90% of predicted. The mREE/pREE quotient was associated to a clinical score for HD symptoms and to radiological hypothalamic damage. Results: In total, 67 children at risk of HD (96% brain tumor diagnosis) with a mean BMI SDS of +2.3 ± 1.0 were included. Of these, 45 (67.2%) had low mREE. Children with severe HD had a significant lower mean mREE/pREE quotient compared to children with no, mild, or moderate HD. Mean mREE/pREE quotient of children with posterior hypothalamic damage was significantly lower compared to children with no or anterior damage. Tumor progression or tumor recurrence, severe clinical HD, and panhypopituitarism with diabetes insipidus (DI) were significant risk factors for reduced REE. Conclusion: REE may be lowered in children with hypothalamic damage and is associated to the degree of clinical HD. REE is, however, not lowered in all children suspect for HD. For children with mild or moderate clinical HD symptoms, REE measurements may be useful to distinguish between those who may benefit from obesity treatment that increases REE from those who would be better helped using other obesity interventions.

Results from the Netherlands' 2018 Report Card and Report Card+ on physical activity for children and youth with and without chronic medical condition.

OBJECTIVE: The objective of this study was to summarize the results of the 2018 the Netherlands' Physical Activity Report Card (PARC) for children and youth as well as for children and youth with a chronic medical condition (CMC; PARC+). STUDY DESIGN: This study is a survey. METHODS: A total of 12 indicators were graded using the Active Healthy Kids Global Alliance PARC development process, which includes a synthesis of the best available research, surveillance, policy and practice findings and expert consensus. Grades were based on the best available evidence and ranged from grade A (>80% of the children succeed) to grade F (less than 20% succeed) or incomplete (INC). Sources included national surveys, peer-reviewed literature and grey literature such as government and non-government reports and online content. RESULTS: Grades assigned for PARC/PARC+ were as follows: Overall Physical Activity: C-/D+; Organized Sports Participation: B/B-; Active Play: D/D; Active Transportation: A-/B+; Sedentary Behaviour: D/D; Physical Fitness: INC /INC; Family and Peers: C/INC; School: C+/A-; Community and Environment: INC /INC; Government: INC /INC; Sleep: A-/B+ and Weight Status: A-/A-, respectively. CONCLUSIONS: The report shows that the Netherlands' youth scores well on (organized) participation in sports and active transport to and from school. However, they do not participate enough in overall physical activity. Despite the fact that outdoor play is the most important exercise activity for children, outdoor play scores an insufficient score for both healthy children and children with a CMC. Sports participation also contributed significantly to daily physical activity. However, sports participation alone is not enough to comply with the national activity guidelines.

Long-term effects of ivacaftor on nonpulmonary outcomes in individuals with cystic fibrosis, heterozygous for a S1251N mutation.

OBJECTIVES: To describe the long-term effects of ivacaftor (Kalydeco®) in individuals with cystic fibrosis (CF) on body mass index (BMI), body composition (BC), pulmonary function (PF), resting energy expenditure (REE), and exercise capacity (EC) after ≥12 months of treatment. WORKING HYPOTHESIS: BMI, lean and fat mass, PF, and EC will increase and REE will decrease after treatment. STUDY DESIGN: Observational study. METHODOLOGY: Seven individuals with CF (mean age 15.4 ± 5.8 years) heterozygous for S1251N mutation, starting with ivacaftor, were included. Paired t tests were performed to assess the effects of ivacaftor. Height and weight were used to calculate BMI and BMI Z-scores. Dual-energy X-ray absorptiometry was used to assess BC. Spirometry and body plethysmography were used to assess PF. Indirect calorimetry was used to measure REE and cardiopulmonary exercise testing (CPET) was used to measure oxygen uptake (VO2peak ), peak work rate (Wpeak ), and other CPET variables. RESULTS: After a median of 15 (interquartile range: 13-16) months of treatment, BMI increased significantly (P = .03), but not BMI Z-score (P = .23) or BC. Significant improvements were found for several PF variables, especially measures of hyperinflation (P = .02). Absolute VO2peak (P = .01), VO2peak related to body weight (P = .00), and oxygen cost of work (P = .01) decreased. Absolute Wpeak (P = .59) and Wpeak related to body weight (P = .31) remained stable. CONCLUSIONS: The results showed that long-term treatment of ivacaftor is associated with improvement of BMI and PF, but not of BC and REE. Oxygen uptake reduced after treatment, which may be due to a decrease in work of breathing.

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 (ρ [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.

Reference values for cardiopulmonary exercise testing in healthy subjects - an updated systematic review.

Introduction: Reference values for cardiopulmonary exercise testing (CPET) parameters provide the comparative basis for answering important questions concerning the normalcy of exercise responses in patients, and significantly impacts the clinical decision-making process. Areas covered: The aim of this study was to provide an updated systematic review of the literature on reference values for CPET parameters in healthy subjects across the life span. A systematic search in MEDLINE, Embase, and PEDro databases were performed for articles describing reference values for CPET published between March 2014 and February 2019. Expert opinion: Compared to the review published in 2014, more data have been published in the last five years compared to the 35 years before. However, there is still a lot of progress to be made. Quality can be further improved by performing a power analysis, a good quality assurance of equipment and methodologies, and by validating the developed reference equation in an independent (sub)sample. Methodological quality of future studies can be further improved by measuring and reporting the level of physical activity, by reporting values for different racial groups within a cohort as well as by the exclusion of smokers in the sample studied. Normal reference ranges should be well defined in consensus statements.

Reference values for maximum work rate in apparently healthy Dutch/Flemish adults: data from the LowLands fitness registry.

Background: The peak oxygen uptake (VO2peak) test is the gold standard for cardiorespiratory fitness. However, the test is demanding, requiring sophisticated apparatus for measuring the oxygen uptake. Peak work rate (WRpeak) testing is a promising substitute for peak VO2peak testing. However, there is a paucity of research conducted to determine reference values (RVs) for WRpeak. Methods: The database from the LowLands fitness registry was used, containing data from health checks from apparently healthy subjects among various professions. Exercise tests were performed using a cycle ergometer and a calibrated metabolic cart. Analysis was executed on 3463 subjects, 2868 male and 595 female. Reference values with corresponding centiles were developed using the LMS method. Results: VO2peak and WRpeak where highly associated with Pearson's correlation of 0.9 (p = .001). Weight, height, maximum heart rate, and the respiratory exchange ratio had a positive significant effect (p < .001) on WRpeak, and age a negative significant effect, in both males and females. The following formulas were computed for RVs: WRpeak=-102+(1.5 * weight[kg])+(1.9 * height[cm])-(2.0 * age)-(sex * 60[M:0;V:1]) WRpeak/kg=2.45-(0.026 * weight[kg])+(0.024 * height[cm])-(0.024 * age)-(sex * 0.84 [M:0;V:1]) Conclusions: WRpeak can be used as a substitute for VO2peak when a respiratory gas-analysis system is not available. This study provides RVs for WRpeak and WRpeak/kg in a healthy Dutch/Flemish adult population using cycle ergometry. Further research is needed to obtain RVs for elderly subjects, specific diseases, ethnicities and ergometers.

Evaluation of Left Ventricular Function Long Term After Arterial Switch Operation for Transposition of the Great Arteries.

Long-term after arterial switch operation for transposition of the great arteries, abnormal coronary anatomy and altered loading conditions could compromise ventricular function. The current study investigates whether left ventricular function, measured with echocardiographic bi-plane ejection fraction and deformation imaging, in patients long term after arterial switch operation for transposition of the great arteries differs from healthy peers. A cross-sectional cohort study of patients at least 12 years after arterial switch operation was analyzed with bi-plane Simpson's left ventricular ejection fraction (LVEF) and deformation (speckle tracking) echocardiography. 81 patients, median age 20.6 (interquartile range 13.5-28.4) years, were included. LVEF was normal on average at 55.5 ± 6.1%. Global longitudinal strain (GLS) was lower in patients compared to healthy peers throughout all age groups and on pooled average (- 15.4 ± 1.1% vs. - 23.2 ± 0.9%). Although LVEF is normal on average in patients after arterial switch operation for transposition of the great arteries, GLS is impaired compared to healthy peers. The reduced GLS could indicate sub-clinical myocardial dysfunction.

[An activity-friendly environment: that's also the doctor's business]. / Een beweegvriendelijke omgeving.

Achieving and maintaining sufficient levels of physical activity is important for the health of the Dutch population. However, the vast majority of the Dutch population - including children - does not comply with the current physical activity guideline. This is the case despite excellent infrastructure which allows safe movement and facilitates walking or cycling to school or work. Perhaps the layout of our living environment is unattractive for movement. It may possibly be unchallenging for young people or too much concrete for adults. In this article we discuss the role of the physical environment on physical activity and ultimately our health. Ways in which the environment could influence the levels of physical activity of the population are also considered.

Cost-effectiveness of a combined physical exercise and psychosocial training intervention for children with cancer: Results from the quality of life in motion study.

This study was performed to estimate the cost-effectiveness of a combined physical exercise and psychosocial intervention for children with cancer compared with usual care. Sixty-eight children, aged 8-18 years old, during or within the first year post-cancer treatment were randomised to the intervention (n = 30) and control group (n = 38). Health outcomes included fitness, muscle strength and quality adjusted life years; all administered at baseline, 4- and 12-month follow-up. Costs were gathered by 1 monthly cost questionnaires over 12 months, supplemented by medication data obtained from pharmacies. Results showed no significant differences in costs and effects between the intervention and control group at 12-month follow-up. On average, societal costs were €299 higher in the intervention group than in the control group, but this difference was not significant. Cost-effectiveness acceptability curves indicated that the intervention needs large societal investments to reach reasonable probabilities of cost-effectiveness for quality of life and lower body muscle strength. Based on the results of this study, the intervention is not cost-effective in comparison with usual care.

Reference value for the 6-minute walk test in children and adolescents: a systematic review.

INTRODUCTION: The 6-minute walk test is a submaximal exercise test used to quantify the functional exercise capacity in clinical populations. It measures the distance walked within a period of 6-minutes. Obtaining reference values in the pediatric population is especially demanding due to factors as the development stage and age. RV provide a comparative basis for answering questions concerning the normality of health status, exercise responses and functional exercise capacity in patients. Areas covered: The aim of this review is to provide an overview of reference values and reference value prediction equations for the 6-minute walk test in the children and in adolescent pediatric population and of the methodology used to obtain them. A total of 22 studies from MEDLINE, EMBASE and Cinahl were included containing healthy participants aged ≤18 years. Reported reference values ranged from 383 m ± 41 m to 799 m ± 54 m. The prediction equation 6MWD = (4.63*height(cm))-(3.53*weight(kg))+(10.42*age)+56.32 yields the highest R2 value (0.6). Expert commentary: It is impossible to present a single best reference value. A flow-chart is presented to aid the selection of reference values or reference value prediction equations. Consensus regarding testing procedures should lead to an update and stricter application of the current guidelines.

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.

Altered Energetics of Exercise Explain Risk of Rhabdomyolysis in Very Long-Chain Acyl-CoA Dehydrogenase Deficiency.

Rhabdomyolysis is common in very long-chain acyl-CoA dehydrogenase deficiency (VLCADD) and other metabolic myopathies, but its pathogenic basis is poorly understood. Here, we show that prolonged bicycling exercise against a standardized moderate workload in VLCADD patients is associated with threefold bigger changes in phosphocreatine (PCr) and inorganic phosphate (Pi) concentrations in quadriceps muscle and twofold lower changes in plasma acetyl-carnitine levels than in healthy subjects. This result is consistent with the hypothesis that muscle ATP homeostasis during exercise is compromised in VLCADD. However, the measured rates of PCr and Pi recovery post-exercise showed that the mitochondrial capacity for ATP synthesis in VLCADD muscle was normal. Mathematical modeling of oxidative ATP metabolism in muscle composed of three different fiber types indicated that the observed altered energy balance during submaximal exercise in VLCADD patients may be explained by a slow-to-fast shift in quadriceps fiber-type composition corresponding to 30% of the slow-twitch fiber-type pool in healthy quadriceps muscle. This study demonstrates for the first time that quadriceps energy balance during exercise in VLCADD patients is altered but not because of failing mitochondrial function. Our findings provide new clues to understanding the risk of rhabdomyolysis following exercise in human VLCADD.

Application of the steep ramp test for aerobic fitness testing in children with cancer.

BACKGROUND: Children with and after cancer are found to have a decreased physical fitness, frequently resulting in decreased physical functioning. The gold standard test for assessing aerobic fitness, a component of physical fitness, is the respiratory gas analyses-based cardiopulmonary exercise test (CPET). However, equipment for gas analysis is often unavailable in local physical therapy centres and non-university hospitals. The steep ramp test (SRT), is a cycle ergometer test with a fast increase in workload, a short duration, and does not require respiratory gas analysis equipment. AIM: The aim of this study was to compare the results of the CPET and the SRT, in children with cancer, and to assess whether the SRT can be used for aerobic fitness assessment in clinical practice in this population. DESIGN: This study is a cross-sectional assessment using baseline data of a randomized controlled trial. SETTING: The study was performed in a hospital setting. POPULATION: Sixty-one children (mean age 12.9 years; 33 boys) with cancer were included in the analysis; 16 children were on non-intensive chemotherapy treatment, 45 were in the first year thereafter. METHODS: Participants performed both the SRT and the CPET on a cycle ergometer with respiratory gas analysis. Data of the two tests were compared and regression analyses were performed. RESULTS: CPET test results revealed a higher impact on the cardiovascular system, as shown by higher peak ventilation (47.8 versus 52.0 Litres per min) and peak heart rates (173 versus 191 beats per min), compared to the SRT. In addition, the test time was significantly longer (90 s versus 390 s). Yet, the primary outcome of the SRT (peak work rate) was able to reliably estimate the peak oxygen uptake of the CPET. CONCLUSION: The peak oxygen uptake was comparable between the SRT and the CPET, although the peak work rate was significantly higher during the SRT. This study showed that the SRT is a valid instrument to assess aerobic fitness in children with cancer. CLINICAL REHABILITATION IMPACT: The SRT is less time consuming and can be performed without gas analysis in a non-clinical setting, making it less demanding for children.

Exercise tolerance in obese vs. lean adolescents: a systematic review and meta-analysis.

To prescribe feasible and medically safe exercise interventions for obese adolescents, it remains to be determined whether exercise tolerance is altered and whether anomalous cardiopulmonary responses during maximal exercise testing are present. Studies that examined cardiopulmonary responses to maximal exercise testing in obese adolescents were searched: cardiopulmonary exercise tests with respiratory gas exchange measurements of peak oxygen uptake (VO2peak) were performed and comparisons between obese and lean adolescents were made. Study quality was assessed using a standardized item list. By meta-analyses VO2peak, peak cycling power output (Wpeak) and peak heart rate (HRpeak) were compared between groups. Nine articles were selected (333 obese vs. 145 lean adolescents). VO2peak (L min(-1)), HRpeak and Wpeak were not different between groups (P ≥ 0.10), while a trend was found for a reduced VO2peak (mL min(-1) kg(-1) lean tissue mass) (P=0.07) in obese vs. lean adolescents. It remained uncertain whether anomalous cardiopulmonary responses occur during maximal exercise testing in obese adolescents. In conclusion, a trend was found for lowered VO2peak (mL min(-1)kg(-1) lean tissue mass) in obese vs. lean adolescents. Whether cardiopulmonary anomalies during maximal exercise testing would occur in obese adolescents remains uncertain. Studies are therefore warranted to examine the cardiopulmonary response during maximal exercise testing in obese adolescents.

Systematic review of the effects of physical exercise training programmes in children and young adults with congenital heart disease.

BACKGROUND: Most patients with congenital heart disease (ConHD) do not perform regular physical exercise. Consensus reports have stated that exercise should be encouraged and regularly performed in these patients, but this is not common practise. We reviewed the literature on actual evidence for either negative or positive effects of physical exercise training programmes in children and young adults with ConHD. METHODS: Using the Medline database, we systematically searched for articles on physical exercise training programmes in ConHD. RESULTS: A total of 31 articles met all inclusion criteria; in total, 621 subjects (age range 4 to 45 years) were included. Most studies used training programmes with a duration of 12 weeks. On average, the number of training sessions was 3 times per week. In 12 studies, training intensity was set at a percentage of peak heart rate. Outcome measures reported were PeakVO2, activity levels and muscle strength. Twenty-three studies (72%) found a significant positive change in the main outcome measure after the physical exercise training period. None of the studies reported negative findings related to physical exercise training in ConHD. Cardiac effects have hardly been studied. CONCLUSION: In most studies, participation in a physical exercise training programme was safe and improved fitness in children and young adults with ConHD. We recommend that patients with ConHD participate in physical exercise training. Cardiac effects need to be studied more extensively.

Validation of the Actical and Actiheart monitor in ambulatory children with spina bifida.

BACKGROUND: Ambulatory children with Spina Bifida (SB) often show a decline in physical activity leading to deconditioning and functional decline. Therefore, assessment and promotion of physical activity is important. Because energy expenditure during activities is higher in these children, the use of existing pediatric equations to predict physical activity energy expenditure (PAEE) may not be valid. AIMS: (1) To evaluate criterion validity of existing predictions converting accelerocounts into PAEE in ambulatory children with SB and (2) to establish new disease-specific equations for PAEE. METHODS: Simultaneous measurements using the Actical, the Actiheart, and indirect calorimetry took place to determine PAEE in 26 ambulatory children with SB. DATA ANALYSIS: Paired T-tests, Intra-class correlations limits of agreement (LoA), and explained variance (R(2)) were used to analyze validity of the prediction equations using true PAEE as criterion. New equations were derived using regression techniques. RESULTS: While T-tests showed no significant differences for some models, the predictions developed in healthy children showed moderate ICC's and large LoA with true PAEE. The best regression models to predict PAEE were: PAEE=174.049+3.861 × HRAR - 60.285 × ambulatory status (R(2) =0.720) and PAEE=220.484+0.67 × Actical counts - 60.717 × ambulatory status (R(2) =0.681). CONCLUSIONS: Existing equations to predict PAEE are not valid for use in children with SB for the individual evaluation of PAEE. The best regression model was based on HRAR in combination with ambulatory status, followed by a new model for the Actical monitor. A benefit of HRAR is that it does not require the use of expensive accelerometry equipment. Further cross-validation of these models is still needed.

Exercise therapy improves mental and physical health in schizophrenia: a randomised controlled trial.

OBJECTIVE: The objective of this multicenter randomised clinical trial was to examine the effect of exercise versus occupational therapy on mental and physical health in schizophrenia patients. METHOD: Sixty-three patients with schizophrenia were randomly assigned to 2 h of structured exercise (n = 31) or occupational therapy (n = 32) weekly for 6 months. Symptoms (Positive and Negative Syndrome Scale) and cardiovascular fitness levels (Wpeak and VO2peak ), as assessed with a cardiopulmonary exercise test, were the primary outcome measures. Secondary outcome measures were the Montgomery and Åsberg Depression Rating Scale, Camberwell Assessment of Needs, body mass index, body fat percentage, and metabolic syndrome (MetS). RESULTS: Intention-to-treat analyses showed exercise therapy had a trend-level effect on depressive symptoms (P = 0.07) and a significant effect on cardiovascular fitness, measured by Wpeak (P < 0.01), compared with occupational therapy. Per protocol analyses showed that exercise therapy reduced symptoms of schizophrenia (P = 0.001), depression (P = 0.012), need of care (P = 0.050), and increased cardiovascular fitness (P < 0.001) compared with occupational therapy. No effect for MetS (factors) was found except a trend reduction in triglycerides (P = 0.08). CONCLUSION: Exercise therapy, when performed once to twice a week, improved mental health and cardiovascular fitness and reduced need of care in patients with schizophrenia.

Recommendations for physical activity, recreation sport, and exercise training in paediatric patients with congenital heart disease: a report from the Exercise, Basic & Translational Research Section of the European Association of Cardiovascular Prevention and Rehabilitation, the European Congenital Heart and Lung Exercise Group, and the Association for European Paediatric Cardiology.

All children have a natural need to move, play, and perform activities. Physical activity is necessary for optimal physical, emotional, and psychosocial development for healthy children as well as children with congenital heart disease (CHD). In this paper we provide recommendations for physical activity, recreational sport, and exercise training in children and adolescents with CHD. In general, children with CHD should be advised to comply with public health recommendations of daily participation in 60 min or more of moderate-to-vigorous physical activity that is developmentally appropriate and enjoyable and involves a variety of activities. While all patients with CHD can participate and benefit from physical activity and exercise, those with specific lesions or complications may require counselling regarding precautions and recommendations.

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

BACKGROUND: There 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. METHODS: A 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 (W(peak)) 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 W(peak) and [2] validated the protocol's ability to provide a maximal effort within a 10±2 minute time frame in 14 adolescents with CF who were tested using this new protocol (protocol validation group). RESULTS: No significant differences were seen in W(peak) and predicted W(peak) 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±2 minute time frame. Backward linear regression analysis resulted in the following equation: W(peak) (W)=-142.865+2.998×Age (years)-19.206×Sex (0=male; 1=female)+1.328×Height (cm)+23.362×FEV(1) (L) (R=.89; R(2)=.79; SEE=21). Bland-Altman analysis showed no systematic bias between the actual and predicted W(peak). CONCLUSION: We developed a CF-specific linear regression model to predict peak workload based on standard measures of anthropometry and FEV(1), which could be used to calculate individualized workload increments for a cycle ergometry testing protocol.