The active control group is offered a home-based training program consisting of combined aerobic, strength and stretching exercises. Further, they will receive monthly motivational consultations, as described below, concerning the training program. The use of the home-based training program will be monitored through exercise journals.

The INT group will receive usual standardized hospital care, including physiotherapy if needed.

Each child and their parents will participate in a monthly 30-minute motivational counseling session to adjust the intervention and training program according to the child's physical capacity and preferences. Further, the session will determine potential barriers towards performing physical exercise using the Self-efficacy for Exercise Scale.

The sessions are based on the principles in Self-Determination Theory that includes a spectrum of external and internal motivation factors for engaging in exercise. Each session will provide guidelines to increase the general activity levels and adjust the intervention according to the child's preferences and presence of symptoms.

Isometric leg extension is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant is instructed to kick (forward) with maximal force keeping maximal intensity for at least five seconds. Three attempts with a two minutes break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. Highest score is noted.

The participant is sitting upright with hands grasping the bench. Hips and knees are kept in 90 degrees flexion. The height of the bench is adjusted to maintain both feet of the ground.

The chain to the dynamometer is adjusted in order to keep the leg in 90 degrees flexion during muscle contraction. The test is performed unilaterally, and in some cases solely on one leg as children with solid tumors in under extremities may be restricted to testing.

Isometric leg extension is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant is instructed to kick (forward) with maximal force keeping maximal intensity for at least five seconds. Three attempts with a two minutes break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. Highest score is noted.

The participant is sitting upright with hands grasping the bench. Hips and knees are kept in 90 degrees flexion. The height of the bench is adjusted to maintain both feet of the ground.

The chain to the dynamometer is adjusted in order to keep the leg in 90 degrees flexion during muscle contraction. The test is performed unilaterally, and in some cases solely on one leg as children with solid tumors in under extremities may be restricted to testing.

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood pressure (mmHg) will be measured in the morning and in the right arm with the subject in the sitting position. TMarkers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Waist circumference is measured in CM, at the end of several consecutive natural breaths, at a level parallel to the floor, midpoint between the top of the iliac crest and the lower margin of the last palpable rib in the mid axillary line following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Waist circumference is measured in CM, at the end of several consecutive natural breaths, at a level parallel to the floor, midpoint between the top of the iliac crest and the lower margin of the last palpable rib in the mid axillary line following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Waist circumference is measured in CM, at the end of several consecutive natural breaths, at a level parallel to the floor, midpoint between the top of the iliac crest and the lower margin of the last palpable rib in the mid axillary line following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3.

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Blood samples will be drawn from an antecubital vein, or when possible, through a central or peripheral venous catheter. Markers of Metabolic Syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Isometric bench press is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant lies in supine position, with shoulder in 150% of biacromial width and elbows in 90 degrees flexion, with the height of the bar adjusted accordingly. The participant is obliged to maintain this position during the test. The participant is instructed to push (upwards) with maximal force.

Isometric bench press is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant lies in supine position, with shoulder in 150% of biacromial width and elbows in 90 degrees flexion, with the height of the bar adjusted accordingly. The participant is obliged to maintain this position during the test. The participant is instructed to push (upwards) with maximal force.

Isometric bench press is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant lies in supine position, with shoulder in 150% of biacromial width and elbows in 90 degrees flexion, with the height of the bar adjusted accordingly. The participant is obliged to maintain this position during the test. The participant is instructed to push (upwards) with maximal force.

Isometric bench press is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant lies in supine position, with shoulder in 150% of biacromial width and elbows in 90 degrees flexion, with the height of the bar adjusted accordingly. The participant is obliged to maintain this position during the test. The participant is instructed to push (upwards) with maximal force.

Isometric bench press is tested using a special-build strength ergometer (Gym 2000®) with a dynamometer (US2A100 kg, Holtinger, Germany).

The participant lies in supine position, with shoulder in 150% of biacromial width and elbows in 90 degrees flexion, with the height of the bar adjusted accordingly. The participant is obliged to maintain this position during the test. The participant is instructed to push (upwards) with maximal force.

Handgrip strength is measured using a hand-held dynamometer. Participants are placed in a seated position with the elbow flexed at 90°, with three attempts performed for each hand. During testing, the participant will be encouraged to exhibit the best possible force, and the best measure in the strongest hand will be used as test score. Hand Grip strength is also used as a surrogate measure for upper-body physical function.

Handgrip strength is measured using a hand-held dynamometer. Participants are placed in a seated position with the elbow flexed at 90°, with three attempts performed for each hand. During testing, the participant will be encouraged to exhibit the best possible force, and the best measure in the strongest hand will be used as test score. Hand Grip strength is also used as a surrogate measure for upper-body physical function.

Handgrip strength is measured using a hand-held dynamometer. Participants are placed in a seated position with the elbow flexed at 90°, with three attempts performed for each hand. During testing, the participant will be encouraged to exhibit the best possible force, and the best measure in the strongest hand will be used as test score. Hand Grip strength is also used as a surrogate measure for upper-body physical function.

Handgrip strength is measured using a hand-held dynamometer. Participants are placed in a seated position with the elbow flexed at 90°, with three attempts performed for each hand. During testing, the participant will be encouraged to exhibit the best possible force, and the best measure in the strongest hand will be used as test score. Hand Grip strength is also used as a surrogate measure for upper-body physical function.

Handgrip strength is measured using a hand-held dynamometer. Participants are placed in a seated position with the elbow flexed at 90°, with three attempts performed for each hand. During testing, the participant will be encouraged to exhibit the best possible force, and the best measure in the strongest hand will be used as test score. Hand Grip strength is also used as a surrogate measure for upper-body physical function.

Maximal walking distance in six minutes, as a surrogate measure for cardiorespiratory fitness, is measured through the self-paced 6-minute walk test. Two cones are positioned on a straight course spaced at 20 m. The object of the test is to walk as far as possible in 6 minutes. Participants must walk back and forth around the cones, permitted to slow down, to stop, and to rest as necessary without running or jogging. The accumulated distance is noted, and degree of perceived exhaustion is estimated using the Borg Category-Ratio 1-10 Scale.

Maximal walking distance in six minutes, as a surrogate measure for cardiorespiratory fitness, is measured through the self-paced 6-minute walk test. Two cones are positioned on a straight course spaced at 20 m. The object of the test is to walk as far as possible in 6 minutes. Participants must walk back and forth around the cones, permitted to slow down, to stop, and to rest as necessary without running or jogging. The accumulated distance is noted, and degree of perceived exhaustion is estimated using the Borg Category-Ratio 1-10 Scale.

Maximal walking distance in six minutes, as a surrogate measure for cardiorespiratory fitness, is measured through the self-paced 6-minute walk test. Two cones are positioned on a straight course spaced at 20 m. The object of the test is to walk as far as possible in 6 minutes. Participants must walk back and forth around the cones, permitted to slow down, to stop, and to rest as necessary without running or jogging. The accumulated distance is noted, and degree of perceived exhaustion is estimated using the Borg Category-Ratio 1-10 Scale.

Maximal walking distance in six minutes, as a surrogate measure for cardiorespiratory fitness, is measured through the self-paced 6-minute walk test. Two cones are positioned on a straight course spaced at 20 m. The object of the test is to walk as far as possible in 6 minutes. Participants must walk back and forth around the cones, permitted to slow down, to stop, and to rest as necessary without running or jogging. The accumulated distance is noted, and degree of perceived exhaustion is estimated using the Borg Category-Ratio 1-10 Scale.

Maximal walking distance in six minutes, as a surrogate measure for cardiorespiratory fitness, is measured through the self-paced 6-minute walk test. Two cones are positioned on a straight course spaced at 20 m. The object of the test is to walk as far as possible in 6 minutes. Participants must walk back and forth around the cones, permitted to slow down, to stop, and to rest as necessary without running or jogging. The accumulated distance is noted, and degree of perceived exhaustion is estimated using the Borg Category-Ratio 1-10 Scale.

Sit-To-Stand is performed using a chair that allows the child to flex the legs at a 90o angle. The child is instructed to fold his/her arms across the chest or to let them hang to the side, stand straight and then touch the chair with their bottom while returning to a seated position. Strong verbal encouragement will be given during the test. Subjects were permitted to use rest periods to complete the one-minute period. The test score equates the number of repetitions during a 60 second period. As a marker for lower extremity muscle strength, the number repetition completed after 30 seconds will be noted.

Sit-To-Stand is performed using a chair that allows the child to flex the legs at a 90o angle. The child is instructed to fold his/her arms across the chest or to let them hang to the side, stand straight and then touch the chair with their bottom while returning to a seated position. Strong verbal encouragement will be given during the test. Subjects were permitted to use rest periods to complete the one-minute period. The test score equates the number of repetitions during a 60 second period. As a marker for lower extremity muscle strength, the number repetition completed after 30 seconds will be noted.

Sit-To-Stand is performed using a chair that allows the child to flex the legs at a 90o angle. The child is instructed to fold his/her arms across the chest or to let them hang to the side, stand straight and then touch the chair with their bottom while returning to a seated position. Strong verbal encouragement will be given during the test. Subjects were permitted to use rest periods to complete the one-minute period. The test score equates the number of repetitions during a 60 second period. As a marker for lower extremity muscle strength, the number repetition completed after 30 seconds will be noted.

The timed Up-and-Go test (TUG) tests basic mobility, defined as the ability to get in and out of bed, to get up and down from a chair, to walk short distances, and to turn.

The test is performed using a chair that allows the child to flex the legs at a 90o angle. From the start position, with the back resting against the chair and arms on knees, the child is instructed to stand up, walk three meters as fast as possible, turn around and return to the start position. Completion time will be recorded in seconds to the nearest two decimals. Strong verbal encouragement will be given during the test. The lowest score of three tries will be used in the analysis.

Sit-To-Stand is performed using a chair that allows the child to flex the legs at a 90o angle. The child is instructed to fold his/her arms across the chest or to let them hang to the side, stand straight and then touch the chair with their bottom while returning to a seated position. Strong verbal encouragement will be given during the test. Subjects were permitted to use rest periods to complete the one-minute period. The test score equates the number of repetitions during a 60 second period. As a marker for lower extremity muscle strength, the number repetition completed after 30 seconds will be noted.

Sit-To-Stand is performed using a chair that allows the child to flex the legs at a 90o angle. The child is instructed to fold his/her arms across the chest or to let them hang to the side, stand straight and then touch the chair with their bottom while returning to a seated position. Strong verbal encouragement will be given during the test. Subjects were permitted to use rest periods to complete the one-minute period. The test score equates the number of repetitions during a 60 second period. As a marker for lower extremity muscle strength, the number repetition completed after 30 seconds will be noted.

The timed Up-and-Go test (TUG) tests basic mobility, defined as the ability to get in and out of bed, to get up and down from a chair, to walk short distances, and to turn.

The test is performed using a chair that allows the child to flex the legs at a 90o angle. From the start position, with the back resting against the chair and arms on knees, the child is instructed to stand up, walk three meters as fast as possible, turn around and return to the start position. Completion time will be recorded in seconds to the nearest two decimals. Strong verbal encouragement will be given during the test. The lowest score of three tries will be used in the analysis.

The timed Up-and-Go test (TUG) tests basic mobility, defined as the ability to get in and out of bed, to get up and down from a chair, to walk short distances, and to turn.

The test is performed using a chair that allows the child to flex the legs at a 90o angle. From the start position, with the back resting against the chair and arms on knees, the child is instructed to stand up, walk three meters as fast as possible, turn around and return to the start position. Completion time will be recorded in seconds to the nearest two decimals. Strong verbal encouragement will be given during the test. The lowest score of three tries will be used in the analysis.

The timed Up-and-Go test (TUG) tests basic mobility, defined as the ability to get in and out of bed, to get up and down from a chair, to walk short distances, and to turn.

The test is performed using a chair that allows the child to flex the legs at a 90o angle. From the start position, with the back resting against the chair and arms on knees, the child is instructed to stand up, walk three meters as fast as possible, turn around and return to the start position. Completion time will be recorded in seconds to the nearest two decimals. Strong verbal encouragement will be given during the test. The lowest score of three tries will be used in the analysis.

The timed Up-and-Go test (TUG) tests basic mobility, defined as the ability to get in and out of bed, to get up and down from a chair, to walk short distances, and to turn.

The test is performed using a chair that allows the child to flex the legs at a 90o angle. From the start position, with the back resting against the chair and arms on knees, the child is instructed to stand up, walk three meters as fast as possible, turn around and return to the start position. Completion time will be recorded in seconds to the nearest two decimals. Strong verbal encouragement will be given during the test. The lowest score of three tries will be used in the analysis.

Number of admissions to hospital (total number of admissions, scheduled and unscheduled admission) will be drawn from the participants medical records

Number of admissions to hospital (total number of admissions, scheduled and unscheduled admission) will be drawn from the participants medical records

Number of admissions to hospital (total number of admissions, scheduled and unscheduled admission) will be drawn from the participants medical records

Bone Mineral Density (g/cm2) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral content (kg) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Body Fat (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Fat-Free Mass (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Density (g/cm2) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Content (kg) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Body Fat (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Fat-Free Mass (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Density (g/cm2) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Content (kg) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Body Fat (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Fat-Free Mass (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Density (g/cm2) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Bone Mineral Content (kg) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Body Fat (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

Fat-Free Mass (kg and %) will be analyzed by whole-body DXA scan (DPX-IQ) (Lunar, Lunar Corporation Madison, WI, USA). Transverse scans at 1 cm intervals are made from head to toe measuring the absorption of x-ray beams at two different energy levels as these are sent through the body.

The Pediatric Quality of Life Inventory (PedsQL Core) measures the quality of life in children using 23 items on a five-point response scale from never to almost always. The answers are divided into four domains: health and physical activity, emotions, dealing with others, and school activity.

The Pediatric Quality of Life Inventory (PedsQL Core) measures the quality of life in children using 23 items on a five-point response scale from never to almost always. The answers are divided into four domains: health and physical activity, emotions, dealing with others, and school activity.

The Pediatric Quality of Life Inventory (PedsQL Core) measures the quality of life in children using 23 items on a five-point response scale from never to almost always. The answers are divided into four domains: health and physical activity, emotions, dealing with others, and school activity.

The Pediatric Quality of Life Inventory (PedsQL Core) measures the quality of life in children using 23 items on a five-point response scale from never to almost always. The answers are divided into four domains: health and physical activity, emotions, dealing with others, and school activity.

Prevalence of Metabolic syndrome, based on markers described above (waist circumference, triglycerides, high-density lipoprotein (HDL) cholesterol, blood pressure, fasting blood sugar and insulin) will be calculated in the Intervention and active control group. Although Children between 6 and 9.9 years cannot be diagnosed with Metabolic syndrome, the potential decline or increase in the biological markers, i.e. predisposition, for metabolic syndrome will, however, be described in this study.

Prevalence of Metabolic syndrome, based on markers described above (waist circumference, triglycerides, high-density lipoprotein (HDL) cholesterol, blood pressure, fasting blood sugar and insulin) will be calculated in the Intervention and active control group. Although Children between 6 and 9.9 years cannot be diagnosed with Metabolic syndrome, the potential decline or increase in the biological markers, i.e. predisposition, for metabolic syndrome will, however, be described in this study.

Prevalence of Metabolic syndrome, based on markers described above (waist circumference, triglycerides, high-density lipoprotein (HDL) cholesterol, blood pressure, fasting blood sugar and insulin) will be calculated in the Intervention and active control group. Although Children between 6 and 9.9 years cannot be diagnosed with Metabolic syndrome, the potential decline or increase in the biological markers, i.e. predisposition, for metabolic syndrome will, however, be described in this study.

Prevalence of Metabolic syndrome, based on markers described above (waist circumference, triglycerides, high-density lipoprotein (HDL) cholesterol, blood pressure, fasting blood sugar and insulin) will be calculated in the Intervention and active control group. Although Children between 6 and 9.9 years cannot be diagnosed with Metabolic syndrome, the potential decline or increase in the biological markers, i.e. predisposition, for metabolic syndrome will, however, be described in this study.

Metabolomics will be performed in urine and plasma for deep metabolomic phenotyping in collaboration with professor L.O. Dragsted (University of Copenhagen). The metabolites (<1500 Da) will be profiled by reversed-phase ultra-high-performance liquid chromatography coupled with a quadrupole - time-of-flight dual mass spectrometer.

Metabolomics will be performed in urine and plasma for deep metabolomic phenotyping in collaboration with professor L.O. Dragsted (University of Copenhagen). The metabolites (<1500 Da) will be profiled by reversed-phase ultra-high-performance liquid chromatography coupled with a quadrupole - time-of-flight dual mass spectrometer.

Metabolomics will be performed in urine and plasma for deep metabolomic phenotyping in collaboration with professor L.O. Dragsted (University of Copenhagen). The metabolites (<1500 Da) will be profiled by reversed-phase ultra-high-performance liquid chromatography coupled with a quadrupole - time-of-flight dual mass spectrometer.

Collection of information regarding the participants dietary intake is based on self-reporting during 3-5days in the online diet program 'Madlog' (Madlog Vita, Vitakost, Kolding Denmark). An overall report of intake calculated in both macro and micronutrients is determined based on the Danish Technical University's (DTU) and the Danish Food Institute's database FRIDA (Frida.com)

Collection of information regarding the participants dietary intake is based on self-reporting during 3-5days in the online diet program 'Madlog' (Madlog Vita, Vitakost, Kolding Denmark). An overall report of intake calculated in both macro and micronutrients is determined based on the Danish Technical University's (DTU) and the Danish Food Institute's database FRIDA (Frida.com)

Collection of information regarding the participants dietary intake is based on self-reporting during 3-5days in the online diet program 'Madlog' (Madlog Vita, Vitakost, Kolding Denmark). An overall report of intake calculated in both macro and micronutrients is determined based on the Danish Technical University's (DTU) and the Danish Food Institute's database FRIDA (Frida.com)

Collection of information regarding the participants dietary intake is based on self-reporting during 3-5days in the online diet program 'Madlog' (Madlog Vita, Vitakost, Kolding Denmark). An overall report of intake calculated in both macro and micronutrients is determined based on the Danish Technical University's (DTU) and the Danish Food Institute's database FRIDA (Frida.com)

Total DNA will be extracted from fecal samples using the Illumina HiSeq technology, generating16S data with the option to later run full microbiome sequencing on selected samples. These studies will be done in collaboration with the National Food Institute, Technical University of Denmark

Total DNA will be extracted from fecal samples using the Illumina HiSeq technology, generating16S data with the option to later run full microbiome sequencing on selected samples. These studies will be done in collaboration with the National Food Institute, Technical University of Denmark

Total DNA will be extracted from fecal samples using the Illumina HiSeq technology, generating16S data with the option to later run full microbiome sequencing on selected samples. These studies will be done in collaboration with the National Food Institute, Technical University of Denmark

Total DNA will be extracted from fecal samples using the Illumina HiSeq technology, generating16S data with the option to later run full microbiome sequencing on selected samples. These studies will be done in collaboration with the National Food Institute, Technical University of Denmark

Total DNA will be extracted from fecal samples using the Illumina HiSeq technology, generating16S data with the option to later run full microbiome sequencing on selected samples. These studies will be done in collaboration with the National Food Institute, Technical University of Denmark

Blood samples will be analyzed for inflammation-related growth factors, chemokines, incretins, epithelial and endothelial markers and cytokines including interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and macrophage-related biomarkers (sCD163 and sCD206), by ELISA or by the Luminex at the Institute of Inflammation Research, Copenhagen University Hospital, Rigshospitalet.

Blood samples will be analyzed for inflammation-related growth factors, chemokines, incretins, epithelial and endothelial markers and cytokines including interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and macrophage-related biomarkers (sCD163 and sCD206), by ELISA or by the Luminex at the Institute of Inflammation Research, Copenhagen University Hospital, Rigshospitalet.

Blood samples will be analyzed for inflammation-related growth factors, chemokines, incretins, epithelial and endothelial markers and cytokines including interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and macrophage-related biomarkers (sCD163 and sCD206), by ELISA or by the Luminex at the Institute of Inflammation Research, Copenhagen University Hospital, Rigshospitalet.

Blood samples will be analyzed for inflammation-related growth factors, chemokines, incretins, epithelial and endothelial markers and cytokines including interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and macrophage-related biomarkers (sCD163 and sCD206), by ELISA or by the Luminex at the Institute of Inflammation Research, Copenhagen University Hospital, Rigshospitalet.

DNA purified from the blood samples will be analyzed for growth-factors gene polymorphism by PCR based technologies including insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), testosterone (and tumor necrosis factor-alpha (TNF-α)) in collaboration with Department for Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet.

DNA purified from the blood samples will be analyzed for growth-factors gene polymorphism by PCR based technologies including insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), testosterone (and tumor necrosis factor-alpha (TNF-α)) in collaboration with Department for Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet.

DNA purified from the blood samples will be analyzed for growth-factors gene polymorphism by PCR based technologies including insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), testosterone (and tumor necrosis factor-alpha (TNF-α)) in collaboration with Department for Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet.

DNA purified from the blood samples will be analyzed for growth-factors gene polymorphism by PCR based technologies including insulin-like growth factor 1 (IGF-1), insulin-like growth factor binding protein 3 (IGFBP-3), testosterone (and tumor necrosis factor-alpha (TNF-α)) in collaboration with Department for Growth and Reproduction, Copenhagen University Hospital, Rigshospitalet.

All counter movement jumps are carried out on a mobile force plate platform (FP4, HUR-Labs Oy, Tampere, Finland). The participant is given instructions on how to perform the CMJ correctly and is given time to familiarize with each test.

The participant stands with both hands resting on the hips. Both hands must stay in this position during the test. The knee angle movement is standardized; participant is instructed to bend down until knees is in a 90-degree angle and immediately hereafter jumps a s high as possible in a vertical direction, landing on both feet simultaneously on the platform.

Three attempts with a one-minute break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. The highest score is noted.

Depending on tumor location, children with solid tumors may be restricted to participate in the counter movement jump.

All counter movement jumps are carried out on a mobile force plate platform (FP4, HUR-Labs Oy, Tampere, Finland). The participant is given instructions on how to perform the CMJ correctly and is given time to familiarize with each test.

The participant stands with both hands resting on the hips. Both hands must stay in this position during the test. The knee angle movement is standardized; participant is instructed to bend down until knees is in a 90-degree angle and immediately hereafter jumps a s high as possible in a vertical direction, landing on both feet simultaneously on the platform.

Three attempts with a one-minute break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. The highest score is noted.

Depending on tumor location, children with solid tumors may be restricted to participate in the counter movement jump.

All counter movement jumps are carried out on a mobile force plate platform (FP4, HUR-Labs Oy, Tampere, Finland). The participant is given instructions on how to perform the CMJ correctly and is given time to familiarize with each test.

The participant stands with both hands resting on the hips. Both hands must stay in this position during the test. The knee angle movement is standardized; participant is instructed to bend down until knees is in a 90-degree angle and immediately hereafter jumps a s high as possible in a vertical direction, landing on both feet simultaneously on the platform.

Three attempts with a one-minute break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. The highest score is noted.

Depending on tumor location, children with solid tumors may be restricted to participate in the counter movement jump.

All counter movement jumps are carried out on a mobile force plate platform (FP4, HUR-Labs Oy, Tampere, Finland). The participant is given instructions on how to perform the CMJ correctly and is given time to familiarize with each test.

The participant stands with both hands resting on the hips. Both hands must stay in this position during the test. The knee angle movement is standardized; participant is instructed to bend down until knees is in a 90-degree angle and immediately hereafter jumps a s high as possible in a vertical direction, landing on both feet simultaneously on the platform.

Three attempts with a one-minute break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. The highest score is noted.

Depending on tumor location, children with solid tumors may be restricted to participate in the counter movement jump.

All counter movement jumps are carried out on a mobile force plate platform (FP4, HUR-Labs Oy, Tampere, Finland). The participant is given instructions on how to perform the CMJ correctly and is given time to familiarize with each test.

The participant stands with both hands resting on the hips. Both hands must stay in this position during the test. The knee angle movement is standardized; participant is instructed to bend down until knees is in a 90-degree angle and immediately hereafter jumps a s high as possible in a vertical direction, landing on both feet simultaneously on the platform.

Three attempts with a one-minute break is carried out, however the participant can try as many attempts as possible if the participant keeps showing improvements. The highest score is noted.

Depending on tumor location, children with solid tumors may be restricted to participate in the counter movement jump.

Neuropathy is evaluated using the Pediatric Modified Total Neuropathy Score (Ped-mTNS)(72). This validated instrument captures impairment-level information on the function of the peripheral nervous system and includes questions on sensory, motor, and autonomic symptoms; examination of light touch, pin, and vibration perception; muscle strength of distal musculature; and deep tendon reflexes.

Neuropathy is evaluated using the Pediatric Modified Total Neuropathy Score (Ped-mTNS)(72). This validated instrument captures impairment-level information on the function of the peripheral nervous system and includes questions on sensory, motor, and autonomic symptoms; examination of light touch, pin, and vibration perception; muscle strength of distal musculature; and deep tendon reflexes.

Neuropathy is evaluated using the Pediatric Modified Total Neuropathy Score (Ped-mTNS)(72). This validated instrument captures impairment-level information on the function of the peripheral nervous system and includes questions on sensory, motor, and autonomic symptoms; examination of light touch, pin, and vibration perception; muscle strength of distal musculature; and deep tendon reflexes.

Neuropathy is evaluated using the Pediatric Modified Total Neuropathy Score (Ped-mTNS)(72). This validated instrument captures impairment-level information on the function of the peripheral nervous system and includes questions on sensory, motor, and autonomic symptoms; examination of light touch, pin, and vibration perception; muscle strength of distal musculature; and deep tendon reflexes.

Neuropathy is evaluated using the Pediatric Modified Total Neuropathy Score (Ped-mTNS)(72). This validated instrument captures impairment-level information on the function of the peripheral nervous system and includes questions on sensory, motor, and autonomic symptoms; examination of light touch, pin, and vibration perception; muscle strength of distal musculature; and deep tendon reflexes.

Total number physiotherapy and occupational therapy treaments (days) will be drawn from the participants medical records.

Total number physiotherapy and occupational therapy treaments (days) will be drawn from the participants medical records.

Total number physiotherapy and occupational therapy treaments (days) will be drawn from the participants medical records.

An validated questionnaire used in the UNGkan and HEIA project will be used to assess self-reported physical activity, physical function, sedentary time, screen time, diet habits, active transportation behavior, physical education participation, perceived barriers/facilitators to physical activity, health-related behaviors. The questionnaire contains four versions targeted either children (<14 years) or youth (>14 years) and the parents guardians to each of these subgroups. The questionnaire contains 35 items for the child/youth report and 18 items for the parent proxy report for both groups.

An validated questionnaire used in the UNGkan and HEIA project will be used to assess self-reported physical activity, physical function, sedentary time, screen time, diet habits, active transportation behavior, physical education participation, perceived barriers/facilitators to physical activity, health-related behaviors. The questionnaire contains four versions targeted either children (<14 years) or youth (>14 years) and the parents guardians to each of these subgroups. The questionnaire contains 35 items for the child/youth report and 18 items for the parent proxy report for both groups.

An validated questionnaire used in the UNGkan and HEIA project will be used to assess self-reported physical activity, physical function, sedentary time, screen time, diet habits, active transportation behavior, physical education participation, perceived barriers/facilitators to physical activity, health-related behaviors. The questionnaire contains four versions targeted either children (<14 years) or youth (>14 years) and the parents guardians to each of these subgroups. The questionnaire contains 35 items for the child/youth report and 18 items for the parent proxy report for both groups.

An validated questionnaire used in the UNGkan and HEIA project will be used to assess self-reported physical activity, physical function, sedentary time, screen time, diet habits, active transportation behavior, physical education participation, perceived barriers/facilitators to physical activity, health-related behaviors. The questionnaire contains four versions targeted either children (<14 years) or youth (>14 years) and the parents guardians to each of these subgroups. The questionnaire contains 35 items for the child/youth report and 18 items for the parent proxy report for both groups.

The PedsQL 3.0 Cancer Module instrument encompasses eight subscales: (1) pain and hurt, (2) nausea, (3) procedural anxiety, (4) treatment anxiety, (5) worry, (6) cognitive problems, (7) perceived physical appearance, and (8) communication

The PedsQL 3.0 Cancer Module instrument encompasses eight subscales: (1) pain and hurt, (2) nausea, (3) procedural anxiety, (4) treatment anxiety, (5) worry, (6) cognitive problems, (7) perceived physical appearance, and (8) communication

Composed og 18 items, the PedsQL Multidimensional Fatigue Scale possesses three subscales: general fatigue, sleep and rest fatigue, and cognitive fatigue.

Composed og 18 items, the PedsQL Multidimensional Fatigue Scale possesses three subscales: general fatigue, sleep and rest fatigue, and cognitive fatigue.

Composed og 18 items, the PedsQL Multidimensional Fatigue Scale possesses three subscales: general fatigue, sleep and rest fatigue, and cognitive fatigue.

Composed og 18 items, the PedsQL Multidimensional Fatigue Scale possesses three subscales: general fatigue, sleep and rest fatigue, and cognitive fatigue.

Self-efficacy for exercise is measured using the Danish version of the SEE scale. This scale contains nine-items concerning nine different potential barriers (weather, activity being tedious, pain, loneliness, disliking the activity, irrelevance, fatigue, stress, sadness) to perform physical exercise.

This four-condition test is designed to assess how well an individual is using sensory inputs to maintain balance when one or more sensory systems are compromised. In condition one, all sensory systems (i.e., vision, somatosensory, and vestibular) are available for maintaining balance. In condition two, vision has been removed and the participant must rely on the somatosensory and vestibular systems to balance. In condition three, the somatosensory system has been compromised and the participant must use vision and the vestibular system to balance. In condition four, vision has been removed and the somatosensory system has been compromised.

Each trial is timed using a stopwatch. The trial is over when (a) the participant opens his/her eyes in an eyes closed condition, (b) raises arms from sides, (c) loses balance and requires manual assistance to prevent a fall or (d) maintains balance for 30 seconds.

This four-condition test is designed to assess how well an individual is using sensory inputs to maintain balance when one or more sensory systems are compromised. In condition one, all sensory systems (i.e., vision, somatosensory, and vestibular) are available for maintaining balance. In condition two, vision has been removed and the participant must rely on the somatosensory and vestibular systems to balance. In condition three, the somatosensory system has been compromised and the participant must use vision and the vestibular system to balance. In condition four, vision has been removed and the somatosensory system has been compromised.

Each trial is timed using a stopwatch. The trial is over when (a) the participant opens his/her eyes in an eyes closed condition, (b) raises arms from sides, (c) loses balance and requires manual assistance to prevent a fall or (d) maintains balance for 30 seconds.

This four-condition test is designed to assess how well an individual is using sensory inputs to maintain balance when one or more sensory systems are compromised. In condition one, all sensory systems (i.e., vision, somatosensory, and vestibular) are available for maintaining balance. In condition two, vision has been removed and the participant must rely on the somatosensory and vestibular systems to balance. In condition three, the somatosensory system has been compromised and the participant must use vision and the vestibular system to balance. In condition four, vision has been removed and the somatosensory system has been compromised.

Each trial is timed using a stopwatch. The trial is over when (a) the participant opens his/her eyes in an eyes closed condition, (b) raises arms from sides, (c) loses balance and requires manual assistance to prevent a fall or (d) maintains balance for 30 seconds.

This four-condition test is designed to assess how well an individual is using sensory inputs to maintain balance when one or more sensory systems are compromised. In condition one, all sensory systems (i.e., vision, somatosensory, and vestibular) are available for maintaining balance. In condition two, vision has been removed and the participant must rely on the somatosensory and vestibular systems to balance. In condition three, the somatosensory system has been compromised and the participant must use vision and the vestibular system to balance. In condition four, vision has been removed and the somatosensory system has been compromised.

Each trial is timed using a stopwatch. The trial is over when (a) the participant opens his/her eyes in an eyes closed condition, (b) raises arms from sides, (c) loses balance and requires manual assistance to prevent a fall or (d) maintains balance for 30 seconds.

This four-condition test is designed to assess how well an individual is using sensory inputs to maintain balance when one or more sensory systems are compromised. In condition one, all sensory systems (i.e., vision, somatosensory, and vestibular) are available for maintaining balance. In condition two, vision has been removed and the participant must rely on the somatosensory and vestibular systems to balance. In condition three, the somatosensory system has been compromised and the participant must use vision and the vestibular system to balance. In condition four, vision has been removed and the somatosensory system has been compromised.

Each trial is timed using a stopwatch. The trial is over when (a) the participant opens his/her eyes in an eyes closed condition, (b) raises arms from sides, (c) loses balance and requires manual assistance to prevent a fall or (d) maintains balance for 30 seconds.

We will interview at least 20 children and their parents from the intervention and control group purposely sampled to represent children with high and low physical activity levels, from all centers, representatives for age, diagnosis and sex.

Physical activity and sedentary time are assessed by accelerometers worn for 7 days during and after treatment. The accelerometers (ActiGraph™ model GT3X+, ActiGraph LLC, Pensacola FL, USA) measures accelerations of ±6 G. The sample rate will be set to measure raw signals at 100 Hz, translated into metabolic energy equivalents of light, moderate and vigorous physical activity and sedentary time.

Physical activity and sedentary time are assessed by accelerometers worn for 7 days during and after treatment. The accelerometers (ActiGraph™ model GT3X+, ActiGraph LLC, Pensacola FL, USA) measures accelerations of ±6 G. The sample rate will be set to measure raw signals at 100 Hz, translated into metabolic energy equivalents of light, moderate and vigorous physical activity and sedentary time.

Physical activity and sedentary time are assessed by accelerometers worn for 7 days during and after treatment. The accelerometers (ActiGraph™ model GT3X+, ActiGraph LLC, Pensacola FL, USA) measures accelerations of ±6 G. The sample rate will be set to measure raw signals at 100 Hz, translated into metabolic energy equivalents of light, moderate and vigorous physical activity and sedentary time.

Physical activity and sedentary time are assessed by accelerometers worn for 7 days during and after treatment. The accelerometers (ActiGraph™ model GT3X+, ActiGraph LLC, Pensacola FL, USA) measures accelerations of ±6 G. The sample rate will be set to measure raw signals at 100 Hz, translated into metabolic energy equivalents of light, moderate and vigorous physical activity and sedentary time.

Physical activity and sedentary time are assessed by accelerometers worn for 7 days during and after treatment. The accelerometers (ActiGraph™ model GT3X+, ActiGraph LLC, Pensacola FL, USA) measures accelerations of ±6 G. The sample rate will be set to measure raw signals at 100 Hz, translated into metabolic energy equivalents of light, moderate and vigorous physical activity and sedentary time.

Weight and Height is combined to report BMI in kg/m^2

Weight and Height is combined to report BMI in kg/m^2

Weight and Height is combined to report BMI in kg/m^2

Weight and Height is combined to report BMI in kg/m^2

Blood samples is reported in mmol/L

Blood samples is reported in mmol/L

Blood samples is reported in mmol/L

Blood samples is reported in mmol/L

An Oral Glucose Tolerance Test is performed in the morning following an overnight fast initiated at 10:00 pm the previous evening. Participants will receive 1.75 g/kg of dextrose (maximum of 75 g). Blood will be sampled for serum insulin and plasma glucose at fasting and at 30, 60, 90 and 120 minutes after dextrose administration. Insulin concentrations is determined using an immunochemiluminometric assay. The insulin assay uses a monoclonal anti-insulin antibody and was run on an Immulite2000 machine (Diagnostic Product Corporation, Los Angeles, California).

An Oral Glucose Tolerance Test is performed in the morning following an overnight fast initiated at 10:00 pm the previous evening. Participants will receive 1.75 g/kg of dextrose (maximum of 75 g). Blood will be sampled for serum insulin and plasma glucose at fasting and at 30, 60, 90 and 120 minutes after dextrose administration. Insulin concentrations is determined using an immunochemiluminometric assay. The insulin assay uses a monoclonal anti-insulin antibody and was run on an Immulite2000 machine (Diagnostic Product Corporation, Los Angeles, California).

An Oral Glucose Tolerance Test is performed in the morning following an overnight fast initiated at 10:00 pm the previous evening. Participants will receive 1.75 g/kg of dextrose (maximum of 75 g). Blood will be sampled for serum insulin and plasma glucose at fasting and at 30, 60, 90 and 120 minutes after dextrose administration. Insulin concentrations is determined using an immunochemiluminometric assay. The insulin assay uses a monoclonal anti-insulin antibody and was run on an Immulite2000 machine (Diagnostic Product Corporation, Los Angeles, California).

An Oral Glucose Tolerance Test is performed in the morning following an overnight fast initiated at 10:00 pm the previous evening. Participants will receive 1.75 g/kg of dextrose (maximum of 75 g). Blood will be sampled for serum insulin and plasma glucose at fasting and at 30, 60, 90 and 120 minutes after dextrose administration. Insulin concentrations is determined using an immunochemiluminometric assay. The insulin assay uses a monoclonal anti-insulin antibody and was run on an Immulite2000 machine (Diagnostic Product Corporation, Los Angeles, California).

Hip circumference (in CM) at a level parallel to the floor, at the largest circumference of the buttocks following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Hip circumference (in CM) at a level parallel to the floor, at the largest circumference of the buttocks following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Hip circumference (in CM) at a level parallel to the floor, at the largest circumference of the buttocks following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).

Hip circumference (in CM) at a level parallel to the floor, at the largest circumference of the buttocks following standards described by the World Health Organization. Metabolic syndrome is based on age-based criterias defined by the International Diabetes Foundation (3).