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Tim Takken
Wilhelmina Children’s Hospital

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" .... Lode ergometers are very reliable and are a good investment for many years...."

We have a long standing positive experience with the Lode equipment. When I started working as a PhD student at the Wilhelmina Children’s Hospital 15 years age, we used a Lode Examiner ergometer. Because we were satisfied with the quality and sustainability of the Lode equipment, we obtained a pediatric Corrival to replace the old Examiner ergometer.

Currently we have several Lode ergometers in our laboratory, including the Lode Corival, pediatric Corival, Corival pediatric, Angio arm ergometer, and the Angio Echo Cardiac Stress Table including the LEM software. We are using the ergometers for both our clinical care as well as scientific research for patients in the age range of 4 to 80 years.
It is our experience that the Lode ergometers are very reliable and are a good investment for many years.
Publications

Towards an individualized protocol for workload increments in cardiopulmonary exercise testing in children and adolescents with cystic fibrosis. (Hulzebos HJ, Werkman MS, van Brussel M, Takken T. )

Date
2012-06-14
Title journal
Towards an individualized protocol for workload increments in cardiopulmonary exercise testing in children and adolescents with cystic fibrosis.
Source
J Cyst Fibros. 2012

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±2minute 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±2minute 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.


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Exercise capacity in children with isolated congenital complete atrioventricularblock: does pacing make a difference? (Blank AC, Hakim S, Strengers JL, Tanke RB, van Veen TA, Vos MA, Takken T. )

Date
2012-02-14
Title journal
Exercise capacity in children with isolated congenital complete atrioventricularblock: does pacing make a difference?
Source
Pediatr Cardiol. 2012;33(4):576-85.

Abstract

The management of patients with isolated congenital complete atrioventricular block (CCAVB) has changed during the last decades. The current policy is to pace the majority of patients based on a variety of criteria, among which is limited exercise capacity. Data regarding exercise capacity in this population stems from previous publications reporting small case series of unpaced patients. Therefore, we have investigated the exercise capacity of a group of contemporary children with CCAVB. Sixteen children (mean age 11.5 ± 4; seven boys, nine girls) with CCAVB were tested. In 13 patients, a median number of three pacemakers were implanted, whereas in three patients no pacemaker was given. All patients had an echocardiogram and completed a cardiopulmonary cycle exercise test. Exercise parameters were determined and compared with reference values obtained from healthy Dutch peers. The peak oxygen uptake/body mass was reduced to 34.4 ± 9.5 ml kg(-1) min(-1) (79 ± 24% of predicted) and the ventilatory threshold was reduced to 52 ± 17% of peak oxygen uptake (78 ± 21% of predicted), whereas the peak work load/body mass was 2.8 ± 0.6 W/kg (91 ± 24% of predicted), which was similar to controls. Importantly, 25% of the paced patients showed upper rate restriction by the pacemaker. In conclusion, children with CCAVB show a reduced peak oxygen uptake and ventilatory threshold, whereas they show normal peak work rates. This indicates that they generate more energy during exercise from anaerobic energy sources. Paced children with CCAVB do not perform better than unpaced children.


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Validity of the oxygen uptake efficiency slope in children with cystic fibrosis and mild-to-moderate airflow obstruction. (Bongers BC, Hulzebos E HJ, Arets B GM, Takken T. )

Date
2012-02-01
Title journal
Validity of the oxygen uptake efficiency slope in children with cystic fibrosis and mild-to-moderate airflow obstruction.
Source
Pediatr Exerc Sci. 2012;24(1):129-41.

Abstract

PURPOSE:

The oxygen uptake efficiency slope (OUES) has been proposed as an 'effort-independent' measure of cardiopulmonary exercise capacity, which could be used as an alternative measurement for peak oxygen uptake (VO(2peak)) in populations unable or unwilling to perform maximal exercise. The aim of the current study was to investigate the validity of the OUES in children with cystic fibrosis (CF).

METHODS:

Exercise data of 22 children with CF and mild to moderate airflow obstruction were analyzed and compared with exercise data of 22 healthy children. The OUES was calculated using data up to three different relative exercise intensities, namely 50%, 75%, and 100% of the total exercise duration, and normalized for body surface area (BSA).

RESULTS:

Only the OUES/BSA using the first 50% of the total exercise duration was significantly different between the groups. OUES/BSA values determined at different exercise intensities differed significantly within patients with CF and correlated only moderately with VO(2peak) and the ventilatory threshold.

CONCLUSION:

The OUES is not a valid submaximal measure of cardiopulmonary exercise capacity in children with mild to moderate CF, due to its limited distinguishing properties, its nonlinearity throughout progressive exercise, and its moderate correlation with VO(2peak) and the ventilatory threshold.


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Effects of Exercise Therapy on Cardiorespiratory Fitness in Schizophrenia Patients. (Scheewe TW, Takken T, Kahn RS, Cahn W, Backx FJ.)

Date
2012-02-19
Title journal
Effects of Exercise Therapy on Cardiorespiratory Fitness in Schizophrenia Patients.
Source
Med Sci Sports Exerc. 2012 Apr 19. [Epub ahead of print]

Abstract

BACKGROUND:

Increased mortality in schizophrenia is caused largely by coronary heart disease. Low cardiorespiratory fitness (CRF) is a key factor for coronary heart disease mortality. We compared CRF in patients with schizophrenia to CRF of matched, healthy controls and reference values. Also, we examined the effects of exercise therapy on CRF in schizophrenia patients and controls.

METHODS:

Sixty-three schizophrenia patients and 55 controls, matched for gender, age, and socioeconomic status, were randomized to exercise (n=31) or occupational therapy (n=32) and controls to exercise (n=27) or life-as-usual (n=28). CRF was assessed with an incremental cardiopulmonary exercise test and defined as the highest relative oxygen uptake (VO2peak) and peak work rate (Wpeak). Minimal compliance was 50% of sessions (n=52).

RESULTS:

Male and female schizophrenia patients had a relative VO2peak of 34.3 (±9.9) ml·kg·min and 24.0 (±4.5) ml·kg·min, respectively. Patients had higher resting heart rate (p<.01) and lower peak heart rate (p<.001), peak systolic blood pressure (p=.02), relative VO2peak (p<.01), Wpeak (p<.001), respiratory exchange rate (p<.001), minute ventilation (p=.02), and heart rate recovery (p<.001) than controls. Relative VO2peak was 90.5 ± 19.7% (p<.01) of predicted relative VO2peak in male and 95.9 ± 14.9% (p=.18) in female patients. In patients, exercise therapy increased relative VO2peak compared to decreased relative VO2peak after occupational therapy. In controls, relative VO2peak increased after exercise therapy and to a lesser extend after life-as-usual (group: p<.01; randomization: p=.03). Exercise therapy increased Wpeak in patients and controls compared to decreased Wpeak in nonexercising patients and controls (p<.001).

CONCLUSION:

Patients had lower CRF-levels compared to controls and reference values. Exercise therapy increased VO2peak and Wpeak in patients and controls. VO2peak and Wpeak decreased in non-exercising patients.


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Near-infrared spectroscopy during exercise and recovery in children with juvenile Dermatomyositis. (Habers G.E., De Knikker R, van BrusselM, HulzebosHJ, StegemanDF, van RoyenA, Takken T. )

Date
2012-01-01
Title journal
Near-infrared spectroscopy during exercise and recovery in children with juvenile Dermatomyositis.
Source
Muscle Nerve. 2012.

Abstract
BACKGROUND
We hypothesized that microvascular disturbances in muscle tissue play a role in the reduced exercise capacity in juvenile dermatomyositis (JDM).
METHODS
Children with JDM, children with juvenile idiopathic arthritis (clinical controls), and healthy children performed a maximal incremental cycloergometric test from which normalized concentration changes in oxygenated hemoglobin (?[O2Hb]) and total hemoglobin (?[tHb]) as well as the half recovery times of both signals were determined from the vastus medialis and vastus lateralis muscles using near-infrared spectroscopy.
RESULTS
Children with JDM had lower ?[tHb] values in the vastus medialis at work rates of 25%, 50%, 75%, and 100% of maximal compared with healthy children; the increase in ?[tHb] with increasing intensity seen in healthy children was absent in children with JDM. Other outcome measures differed not by group.
DISCUSSION
The results suggest that children with JDM may experience difficulties in increasing muscle blood volume with more strenuous exercise.


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Habitual physical activity in Dutch children and adolescents with haemophilia. (Groen WG, Takken T, van der Net J, Helders PJ, Fischer K. )

Date
2011-01-01
Title journal
Habitual physical activity in Dutch children and adolescents with haemophilia.
Source
Haemophilia. 2011;17(5):e906-12.

Abstract
For patients with haemophilia, a physically active lifestyle is important to maintain musculoskeletal health and to prevent chronic diseases, such as cardiovascular disease. Therefore, we studied physical activity levels, in Dutch children and adolescents with haemophilia as well as its association with aerobic fitness and joint health. Forty-seven boys with haemophilia (aged 8-18) participated. Physical activity was measured using the Modifiable Activity Questionnaire (MAQ) and was compared with the general population. Aerobic fitness was determined using peak oxygen uptake (VO(?peak)). Joint health was measured using the Haemophilia Joint Health Score (HJHS). Associations between physical activity, joint health and aerobic fitness were evaluated by correlation analysis. Subjects were 12.5 (SD 2.9) years old, had a Body Mass Index (BMI) of 19.5 (SD 3.1; z-score 0.5) and a median HJHS score of 0 (range 0-6). Cycling, physical education and swimming were most frequently reported (86%, 69% and 50% respectively). Children with severe haemophilia participated significantly less in competitive soccer and more in swimming than children with non-severe haemophilia. Physical activity levels were similar across haemophilia severities and comparable to the general population. VO(?peak) kg?¹ was slightly lower than healthy boys (42.9 ± 8.6 vs. 46.9 ± 1.9 mL kg?¹ min?¹; P = 0.03). Joint health, aerobic fitness and physical activity showed no correlation. Dutch children with haemophilia engaged in a wide range of activities of different intensities and showed comparable levels of physical activity to the general population. Aerobic fitness was well preserved and showed no associations with physical activity levels or joint health.



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Supramaximal Verification of Peak Oxygen Uptake in Adolescents With Cystic Fibrosis (Werkman MS, Hulzebos HJ, van de Weert-van Leeuwen PB, Arets HGM, Helders, PJM, Takken T. )

Date
2011-01-01
Title journal
Supramaximal Verification of Peak Oxygen Uptake in Adolescents With Cystic Fibrosis
Source
Ped Phys Ther. 2011; 23(1): 15-21

Abstract
PURPOSE: To study whether peak oxygen uptake ((Equation is included in full-text article VO??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 VO??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 VO???peak/kg and no differences between CPET and SRT (Equation is included in full-text article VO???peak values within and between the maximal and non-maximal effort groups (P > .4).

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



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Respiratory Gas Exchange During Exercise in Children with Congenital Heart Disease: Methodology and Clinical Concepts. (Takken T, Blank AC, Hulzebos H)

Date
2011-08-01
Title journal
Respiratory Gas Exchange During Exercise in Children with Congenital Heart Disease: Methodology and Clinical Concepts.
Source
Current Respiratory Medicine Reviews. 2011; 7: 87-96.

Cardiopulmonary exercise testing (CPET) in pediatric patients differs in many aspects from the tests as performed in adults. Children's cardiopulmonary responses during exercise testing present different characteristics, particularly indices of respiratory gas exchange (e.g. oxygen uptake, ventilation and ventilatory efficiency), which are essential in interpreting hemodynamic data. Diseases that are associated with myocardial ischemia are very rare in children. Important indications for CPET in children are the evaluation of exercise capacity and the non-invasive identification of pathologic features. In this article we will review the methodology, and clinical concepts exercise testing and interpretation of respiratory gas-exchange during exercise in children with congenital heart disease.



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The steep ramp test in healthy children and adolescents: reliability and validity. (Bart C. Bongers, Sanne de Vries, Paul J.M. Helders and Tim Takken)

Date
2013-02-24
Title journal
The steep ramp test in healthy children and adolescents: reliability and validity.
Source
Medicine and Science in Sports and Exercise

Abstract
PURPOSE:

This study aimed to examine the reliability and validity of the steep ramp test (SRT), a feasible, maximal exercise test on a cycle ergometer that does not require the use of respiratory gas analysis, in healthy children and adolescents.
METHODS:

Seventy-five children were randomly divided in a reliability group (n = 37, 17 boys and 20 girls; mean ± SD age = 13.86 ± 3.22 yr), which performed two SRTs within 2 wk, and a validity group (n = 38, 17 boys and 21 girls; mean ± SD age = 13.85 ± 3.20 yr), which performed both an SRT and a regular cardiopulmonary exercise test (CPET) with respiratory gas analysis within 2 wk. Peak work rate (WRpeak) was the main outcome of the SRT. Peak oxygen uptake (VO2peak) was the main outcome of the CPET. Reliability was examined with the intraclass correlation coefficient and a Bland and Altman plot, whereas validity was assessed using Pearson correlation coefficients and stepwise linear regression analysis.
RESULTS:

Reliability statistics for the WRpeak values attained at the two SRTs showed an intraclass correlation coefficient of 0.986 (P < 0.001). The average difference between the two SRTs was -6.4 W, with limits of agreement between +24.5 and -37.5 W. A high correlation between WRpeak attained at the SRT and the V?O2peak achieved during the CPET was found (r = 0.958; P < 0.001). Stepwise linear regression analysis provided the following prediction equation: VO2peak (mL·min) = (8.262 WRpeak SRT) + 177.096 (R2 = 0.917, SEE = 237.4).
CONCLUSION:

The results suggest that the SRT is a reliable and valid exercise test in healthy children and adolescents, which can be used to predict VO2peak.

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The Steep Ramp Test in Dutch Caucasian Children and Adolescents: Age- and Sex- Related Normative Values (Bongers BC, de Vries SI, Obeid J, van Buuren S, Helders PJ, Takken T)

Date
2013-05-30
Title journal
The Steep Ramp Test in Dutch Caucasian Children and Adolescents: Age- and Sex- Related Normative Values
Source
Physical Therapy

BACKGROUND:

The steep ramp test (SRT) is a feasible, reliable, and valid exercise test on a cycle ergometer that may be more appealing for use in children in daily clinical practice than the traditional cardiopulmonary exercise test, because of its short duration, its resemblance to children's daily activity pattern and the fact that it does not require respiratory gas analysis.
OBJECTIVE:

The aim of the current study was to provide sex- and age-related norm values for SRT performance in healthy Dutch Caucasian children and adolescents between the ages of 8 and 19 years.
DESIGN:

This was a cross-sectional, observational study.
METHODS:

Two hundred and fifty-two Dutch Caucasian children and adolescents, 118 boys (mean age 13.4 (3.0) years) and 134 girls (mean age 13.4 (2.9) years), performed a SRT (work rate increments of 10, 15, or 20 W·10 s-1, depending on body height) to voluntary exhaustion to assess peak work rate (WRpeak). Norm values are presented as reference centiles developed using generalized additive models for location, scale, and shape (GAMLSS).
RESULTS:

WRpeak correlated highly with age (r=0.915 and r=0.811), body mass (r=0.870 and r=0.850), body height (r=0.922 and r=0.896), body surface area (r=0.906 and r=0.885), and fat free mass (r=0.930 and r=0.902), for boys and girls respectively (P<0.001 for all coefficients). The reference curves demonstrated an almost linear increase with age in WRpeak in boys, even when normalized for body mass. In contrast, absolute WRpeak in girls increased constantly until the age of approximately 13 years, where after WRpeak started to level off. WRpeak normalized for body mass showed only a slight increase with age in girls, with a slight decrease in relative WRpeak as of the age of 14 years.
LIMITATIONS:

The sample may not be entirely representative of the Dutch population.
CONCLUSIONS:

The current study provides sex- and age-related norm values for SRT performance for both absolute and relative WRpeak thereby facilitating the interpretation of SRT results for clinicians and researchers.

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Estimating peak oxygen uptake in adolescents with cystic fibrosis (Werkman MS, Hulzebos EH, Helders PJ, Arets BG, Takken T.)

Date
2013-07-26
Title journal
Estimating peak oxygen uptake in adolescents with cystic fibrosis
Source
Archives of disease in childhood

To predict peak oxygen uptake (VO2peak) from the peak work rate (Wpeak) obtained during a cycle ergometry test using the Godfrey protocol in adolescents with cystic fibrosis (CF), and assess the accuracy of the model for prognostication clustering.
METHODS:

Out of our database of anthropometric, spirometric and maximal exercise data from adolescents with CF (N=363; 140 girls and 223 boys; age 14.77±1.73 years; mean expiratory volume in 1 s (FEV1%pred) 86.82±17.77%), a regression equation was developed to predict VO2peak (mL/min). Afterwards, this prediction model was validated with cardiopulmonary exercise data from another 60 adolescents with CF (28 girls, 32 boys; mean age 14.6±1.67 years; mean FEV1%pred 85.43±20.01%).
RESULTS:

We developed a regression model VO2peak (mL/min)=216.3-138.7×sex (0=male; 1=female)+11.5×Wpeak; R2=0.91; SE of the estimate (SEE) 172.57. A statistically significant difference (107 mL/min; p<0.001) was found between predicted VO2peak and measured VO2peak in the validation group. However, this difference was not clinically relevant because the difference was within the SEE of the model. Furthermore, we found high positive predictive and negative predictive values for the model for prognostication clustering (PPV 50-87% vs NPV 82-94%).
CONCLUSIONS:

In the absence of direct VO2peak assessment it is possible to estimate VO2peak in adolescents with CF using only a cycle ergometer. Furthermore, the regression model showed to be able to discriminate patients in different prognosis clusters based on exercise capacity.
KEYWORDS:

Cystic Fibrosis, Exercise, Paediatric Lung Disaese

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