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Archives of Physical Medicine and Rehabilitation 2014;95:1646-55

ORIGINAL ARTICLE

Can a Lifestyle Intervention Improve Physical Fitnessin Adolescents and Young Adults With SpasticCerebral Palsy? A Randomized Controlled Trial

Jorrit Slaman, MSc,a,b Marij Roebroeck, PhD,a Wilma van der Slot, MD, PhD,a,b

Jos Twisk, PhD,c Akkelies Wensink, MD,d Henk Stam, MD, PhD, FRCP,a

Rita van den Berg-Emons, PhD,a and LEARN 2 MOVE Research Group

From the aDepartment of Rehabilitation, Research Lines MoveFit & Transition Into Adulthood, Erasmus Medical Center, University MedicalCenter, Rotterdam; bRijndam Rehabilitation Center, Rotterdam; cVU Medical Center, Amsterdam; and dRehabilitation Center De Hoogstraat,Utrecht, The Netherlands.

Abstract

Objective: To evaluate both the short- and long-term effectiveness of a lifestyle intervention on physical fitness in adolescents and young adults

with cerebral palsy (CP).

Design: Single-blind, randomized controlled trial.

Setting: University hospitals and rehabilitation clinics.

Participants: Adolescents and young adults (NZ57) with spastic CP classified in Gross Motor Function Classification System levels I through

IV; of these, 42 completed the study.

Intervention: A 6-month lifestyle intervention consisting of physical fitness training combined with counseling sessions focused on physical

behavior and sports participation.

Main Outcome Measures: Physical fitness, including measures of cardiopulmonary fitness, muscle strength, and body composition.

Results: Favorable short- and medium-term effects were found for peak oxygen consumption, oxygen consumption, and load on the anaerobic

threshold and waist circumference. Favorable long-term effects were found for sum of skinfolds, systolic blood pressure, and total cholesterol.

Conclusions: This exploratory study showed that the lifestyle intervention was effective in improving cardiopulmonary fitness and body

composition. Effects of body composition were maintained in the long term. However, the intervention needs to be optimized to increase muscle

strength and for long-term retention of effects on aerobic capacity.

Archives of Physical Medicine and Rehabilitation 2014;95:1646-55

ª 2014 by the American Congress of Rehabilitation Medicine

Sufficient physical fitness and physical activity (PA) are majorcontributors to a healthy lifestyle for the general population,1

particularly because of their inverse relation to total and cardio-vascular mortality.2 For persons with cerebral palsy (CP), definedas “a group of permanent disorders of the development ofmovement and posture, causing activity limitation that are

Supported by Netherlands Organisation for Health Research and Development (grant no.

89000002) and Phelps Stichting (grant no. 2008039).

This project is part of the Dutch LEARN 2 MOVE research program.

Clinical Trial Registration No.: NTR1785.

Disclosures: none.

0003-9993/14/$36 - see front matter ª 2014 by the American Congress of Re

http://dx.doi.org/10.1016/j.apmr.2014.05.011

attributed to non-progressive disturbances that occurred in thedeveloping foetal or infant brain,”3(p9) sufficient physical fitnessand PA is likely to be even more important. In addition to healthbenefits, sufficient physical fitness and PA are believed to maintainand optimize daily life performance4 and prevent the developmentof secondary health problems in adulthood.5 Nevertheless,research consistently shows that people with CP have low levels ofphysical fitness6-9 and PA.10-13

During adolescence, there are many changes occurring withsubstantial impact on the development of the adult lifestyle.14,15

Therefore, improving physical fitness and incorporating suffi-cient PA at this age seem to be an appropriate goal to benefit the

habilitation Medicine

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Effectiveness of a lifestyle intervention 1647

person through their lifespan. Important health-related compo-nents of physical fitness are cardiopulmonary fitness, bodycomposition, and muscle strength.16 Children, adolescents, andyoung adults with CP benefit from all these measures of physicalfitness directly after the interventions as described in 2 systematicreviews.17,18 However, both reviews indicate that cardiopulmonaryfitness tends to return to baseline at follow-up.17,18 Also, benefitsto muscle strength were no longer present at follow-up in 2 out of5 studies in the review by Verschuren et al.17 Apparently, offeringa temporary intervention focused on improving physical fitness isinsufficient to maintain improvements in physical fitness over thelong term in persons with CP. Behavioral change toward a moreactive lifestyle may be more effective in the long term. Counselingsessions appear promising to achieve behavioral changes amongpersons with physical disabilities.19,20 Therefore, the active life-style and sports participation intervention was developed in TheNetherlands to increase physical fitness and PA through behavioralchange in adolescents and young adults with childhood-onsetphysical disabilities.21 The present study is part of the LEARN2 MOVE 16-24 study,22 and its aim is to evaluate the effectivenessof this active lifestyle and sports participation intervention onphysical fitness in adolescents and young adults with spastic CP.Effects of the intervention on other outcome measures (eg, PA,fatigue, participation, quality of life) will be presented in forth-coming publications. By offering an exercise program combinedwith PA counseling to achieve behavioral changes toward morePA, effects on physical fitness are expected in both the short andlong terms.

Methods

Study design

The present study is a multicenter trial with a randomizedcontrolled design. To obtain equally distributed gross motorfunctioning between experimental and control groups, stratifica-tion of participants was performed using the Gross Motor Func-tioning Classification System (GMFCS).23 Random allocation ofparticipants to these groups (1:1) was performed for eachparticipating center and within each stratum. The active lifestyleand sports participation intervention was received by the experi-mental group, whereas no intervention to improve physicalbehavior and fitness was received by the control group. In-dividuals allocated to the control group continued their regulartreatments. These regular treatments consisted of physiotherapyfor slightly >80% of control group participants and had anaverage duration of 2 hours per week. However, in contrast withthe active lifestyle and sports participation intervention, theseregular treatments were not aimed at increasing fitness or PAlevels. Assessors performing the study measurements were blin-ded to group allocation.

List of abbreviations:

AT anaerobic threshold

CP cerebral palsy

CPET cardiopulmonary exercise testing

GEE generalized estimating equation

GMFCS Gross Motor Function Classification System

PA physical activity

VO2peak peak oxygen consumption

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Setting and participants

Review of health records at 4 rehabilitation centers and 2 reha-bilitation departments at university hospitals throughout thewestern-central part of The Netherlands identified eligible par-ticipants. Persons were eligible if they met the following inclusioncriteria: diagnosed with spastic unilateral or bilateral CP; age 16 to24 years old; and GMFCS levels I to IV. Persons were excluded ifthey had any of the following: disabilities other than CP affectingcardiopulmonary fitness or PA; contraindication to (maximal)exercise24; exceeding the mean PA level þ 2 SD of a CP popu-lation10 as measured with an accelerometry-based activitymonitor25 corresponding to 263 minutes of PA per day; or insuf-ficient understanding of the project caused by severe cognitiveimpairment or insufficient comprehension of the Dutch language.An informational letter, including an invitation to participate, wassent to eligible persons. Three weeks later, nonresponders receiveda reminder letter. Written informed consent was provided by allparticipants. The study was approved by the medical ethicscommittee of the Erasmus Medical Center. All participatingcenters granted local approval.

We identified a target population of 456 adolescents and youngadults with CP in the patient registers of participating centers.Many patients had not received care at a rehabilitation center formany years. Therefore, the accuracy of their contact informationwas uncertain. A total of 183 potential participants responded toour invitation; of these, 57 (31%) consented to participate, and 42completed the study (fig 1).

Intervention

The active lifestyle and sports participation intervention aims topermanently increase physical fitness and PA levels and reducesedentary behavior. The intervention is targeted at adolescents andyoung adults with physical disabilities and promotes a more activelifestyle. The active lifestyle and sports participation interventionconsisted of 3 parts. The first included weekly supervised centerand weekly home-based physical fitness training with a focus onincreasing levels of cardiopulmonary fitness and muscle strengthoffered by a physical therapist for a period of 3 months. Thesecond included counseling on daily PA, which was based onmotivational interviewing.26 Barriers and facilitators of PA indaily life were discussed, and increasing PA and minimizingsedentary behavior were encouraged during these sessions. Intotal, 6 monthly sessions with a duration of 30 minutes wereoffered and guided by a personal coach (physical therapist/movement therapist). The third part included counseling on sportsparticipation, which was carried out to find accessible, suitable,and appropriate sports and sports facilities conveniently located ineach participant’s environment. In total, 2 to 4 sports counselingsessions were offered by a movement therapist over a period of 6months depending on the participant’s desires. Furthermore,optional sport-specific training was offered, which includedpractice opportunities to match sports to participants’ interests andabilities.21 A time schedule of the active lifestyle and sportsparticipation intervention is presented in table 1. Details of theactive lifestyle and sports participation intervention have beendescribed elsewhere.22

The training frequency of the active lifestyle and sportsparticipation intervention did not meet guidelines for cardiopul-monary exercise training.27 However, the content of the coun-seling and sport-specific training was considered because it also


Fig 1 Flowchart of participants through the study. Abbreviation: ASLP, active lifestyle and sports participation.

1648 J. Slaman et al

required time and physical effort. Therefore, a training frequencyof 2 times a week was assumed to be practically feasible for theactive lifestyle and sports participation intervention to respect theload/capacity ratio of participants.

Measurements

All measurements were performed at 4 points in time: prior torandomization (t0); directly after completing the fitness trainingportion of the intervention, which was 3 months after starting theintervention (t3); directly after completing the entire intervention,including counseling, which was 6 months after starting theintervention (t6); and a follow-up measurement 6 months afterfinishing the intervention (t12). Three components of physicalfitness were measured in the present study: cardiopulmonaryfitness, body composition, and muscle strength.

Cardiopulmonary fitness

Peak oxygen consumption (VO2peak) was measured using a pro-gressive ramp protocol during cardiopulmonary exercise testing(CPET). This test was performed on electronically braked cycle orarm-crank ergometers depending on each person’s primary mode ofambulation during daily life to elicit the highest oxygen consump-tion levels.28 Peak VO2 (mL/min) was defined as the highest meanoxygen consumption during 30 seconds of exercise. The ventilatoryequivalent method was used to estimate oxygen consumption at theventilatory anaerobic threshold (AT) (mL/min).29 Furthermore, themaximum load and load at the ATwere analyzed and expressed inwatts. We applied 2 objective criteria for maximal exercise: amaximum heart rate of at least 175 beats per minute, which repre-sents 90% of the predicted maximum heart rate in adolescents with

CP,30 and a respiratory exchange ratio �1.1.31 A detailed descrip-tion of the applied CPET protocol is available elsewhere.22

Body composition

Height was measured in a standing position. In case of jointcontractures, length was measured joint to joint in a lying position.A Seca scalea was used to obtain body mass of ambulatory par-ticipants, and an electronic Cormier sitting scaleb was used toweigh nonambulatory participants. Waist circumference (cm) wasmeasured in ambulatory persons midway between the iliac crestand lowest rib while standing, whereas this was measured in asitting position for nonambulatory persons. A Harpenden SkinfoldCaliperc was used to measure skinfold thickness (biceps, triceps,subscapular, suprailiac). These measurements were repeated twiceon the left side of the body.

Vacutainer needles were used to draw nonfasting blood sam-ples of 10mL, which were collected in evacuated serum separatortubes II. High-density lipoprotein cholesterol, total serumcholesterol, and the ratio between total serum cholesterol andhigh-density lipoprotein were determined from the blood samples.

Muscle strength

Muscle strength of the knee extensors, hip abductors, and hipflexors was measured in ambulatory participants, whereas musclestrength of the elbow extensors and shoulder abductors wasmeasured in nonambulatory participants. Measurements wereperformed bilaterally with a handheld dynamometerd using thebreak testing method.32 Three trials were performed per musclegroup, with a trial duration of approximately 4 seconds and 1minute of rest between each trial. The mean value of the trialsfor both sides was calculated for each muscle group. A detailed



Table 1 Time schedule of the active lifestyle and sports participation intervention

Week Measurements Counseling on Daily PA

Fitness Training

Sports AdviceSupervised Home Based

Week 1 Pretest (t0) PA session 1

Week 2 Training 1 Training 2

Week 3 Training 3 Training 4 Sports session 1


Week 5 PA session 2 Training 7 Training 8





Week 10 PA session 3 Training 17 Training 18 Sports session 2




Week 14 Posttest 1 (t3)

Week 15 PA session 4

Week 16

Week 17 (Sports session 3)

Week 18

Week 19


Week 21

Week 22

Week 23

Week 24 (Sports session 4)


Week 26 Posttest 2 (t6)

Week 52 Follow-up test (t12)

NOTE. The intervention group followed the described intervention. The control group received no treatment and only participated in the measurements.

Advice in parentheses is not obligatory.


description of the applied protocol to obtain muscle force isavailable elsewhere.22

Statistical analysis

Because the current study is part of the LEARN 2 MOVE 16-24study,22 the power analysis was performed on PA because this aprimary outcome measure of the total randomized controlled trial.Therefore, the study was not powered for the outcomes analyzed inthis study, and we will consider our results as exploratory. To detecta change of 30 minutes per day in total daily PA between thecontrol and experimental groups with a power of 0.8 and an a of.05, we had to include 50 participants. We aimed to recruit 60participants to allow for dropouts. American College of SportsMedicine guidelines for healthy adults recommend at least 30 mi-nutes of moderate intense PA 5 times a week, preferably in bouts ofat least 10 minutes.27 Because activities in persons with CP aremore burdensome than in healthy persons,6 these guidelines maynot be suitable for the population with CP. Because of this and theinactive lifestyle found in CP,10,13 we considered a daily 30-minutechange in PA (regardless of the intensity and duration of continuousbouts) as a clinically relevant effect of the intervention. The poweranalysis was based on data from our previous research.10

Chi-square tests were used to test for differences at baselinewith respect to sex, CP distribution (unilateral or bilateral CP), andGMFCS level between the control and intervention groups.


Independent sample t tests were used to test for differences atbaseline with respect to age, body mass, height, VO2peak, waistcircumference, and muscle strength.

We used generalized estimating equation (GEE) analyses,which were more appropriate than using repeated-measuresanalysis of variance because of missing data in our dataset.Furthermore, the GEE was preferred over linear mixed modelsbecause it is slightly more robust for relatively small samplesizes.33 GEE analyses were applied for each outcome measure.33

For these analyses, identity link functions were used, andexchangeable correlation structures were assumed. Group alloca-tion, baseline values of the particular outcome variable, mea-surement time, and an interaction variable between groupallocation and measurement time were added to the GEE to beable to compare group outcomes for specific time intervals. Thesetime intervals were the exercise training period (t0et3), totalintervention period (t0et6), and follow-up period (t6et12). Incase of significant effects of the intervention between the controland intervention group, additional GEE analyses were performedper group to gain insight into the within-group effect of the activelifestyle and sports participation intervention. These models werespecified per group and included measurement time as a factor.The presented differences from these GEE models represent thedifference between groups over the specified time period. Thecontrol group was the referent group for all analyses. SPSSversion 20e was used for all statistical analyses.



Results

Personal and clinical characteristics of the study sample at baselineare presented in table 2 for the complete study sample and speci-fied per allocated group. Apart from waist circumference (PZ.04),none of the characteristics differed between the control and inter-vention groups. Participants who completed the interventionattended, on average, 89% of the supervised training sessions.

In total, 28 of 178 CPET measurements did not meet theobjective criteria for maximal exercise (13 measurements from thecontrol group, 15 measurements from the intervention group) andtherefore were not analyzed. These 28 measurements (from 18participants) included all CPET measurements performed on thearm-crank ergometer (8 measurements), on which it appearedimpossible to reach maximal exercise because of the physicaldisabilities of participants. For the remaining 20 measurements,participants appeared to lack motivation for maximal exercise.Waist circumference was measured during standing in all but 2participants. Blood observation was incomplete because collectionwas impossible at 1 center (28 observations), lack of consent (24observations), and logistic reasons (42 observations). Therefore,84 blood observations remained out of 178 for analysis. Musclestrength was measured on the lower extremity for all but 4 non-ambulatory participants (3 from the control group, 1 from theintervention group). Muscle strength was measured on the upperextremity in these 4 participants. Because of the low number ofupper-extremity measurements, no analyses were performed onupper-extremity muscle force.

Intervention effects

The observed data over time are presented in tables 3 and 4 andshow the results of the associated longitudinal analyses. For spe-cific time intervals, we found significant effects of the interventionfor the experimental group compared with the control group (seetable 4). Significant increases in cardiopulmonary fitness werefound for the intervention group for oxygen consumption on theAT (differenceZ300, P<.01) and load on the AT (differenceZ27,P<.01) between t0 and t3. Furthermore, VO2peak (differ-enceZ195, P<.01), oxygen consumption on the AT (differ-enceZ325, P<.01), and load on the AT (differenceZ36, P<.01)increased in the intervention group compared with the controlgroup between t0 and t6. For body composition, a decrease in

Table 2 Baseline participant characteristics

Characteristic All

n 57

Sex (M/F) 27/30

Age (y) 20�3

Body mass (kg) 67�18

Height (cm) 170�10

CP distribution (unilateral/bilateral)* 29/27

GMFCS23 level (I/II/III/IV) 33/18/5/1

VO2peak (mL/min) 2397�780

Waist circumference (cm) 83�14

Total lower-extremity muscle strength (n) 1397�515

Total upper-extremity muscle strength (n) 461�34

NOTE. Data are presented as n, mean � SD, or as otherwise indicated.

Abbreviations: F, female; M, male; NA, not applicable.

* CP distribution for 1 person from the control group is unknown.

waist circumference was found for the intervention group betweent0 and t3 (differenceZ�4, PZ.04). Furthermore, during thefollow-up period, decreases in sum of skinfolds (differenceZ�12,PZ.01), systolic blood pressure (differenceZ�10.18, PZ.03),and total cholesterol (differenceZ�.55, PZ.05) were found forthe intervention group compared with the control group. No sig-nificant effects were found for muscle strength. Table 5 shows theresults of the within-group analyses.

Discussion

In our sample of adolescents and young adults with spastic CP,VO2peak at baseline was 17% lower (P<.01) than individuallycalculated healthy norm values for peak cardiopulmonary fitness,using the formula from Jones et al.34 This finding is consistentwith previous results of decreased peak cardiopulmonary fitness inpersons with CP.35-37 Active lifestyle and sports participationintervention effects were promising for several cardiopulmonaryfitness outcomes. The oxygen consumption on the AT and load onthe AT increased directly after completing the physical fitnesstraining of the intervention (t3) and remained through the totalintervention period (t6), whereas the physical fitness training had aduration of only 3 months. Peak VO2 intervention effects were alsopresent for the entire 6-month intervention period. In contrast withregular exercise programs,17,18 active lifestyle and sports partici-pation intervention effects were maintained for at least 3 monthsafter physical fitness training. This persistence is likely attribut-able to the counseling sessions regarding incorporation of exerciseand PA into daily life. However, these effects were no longerpresent at follow-up, half a year after intervention completion.Booster strategies (eg, phone, mail, Internet support) could facil-itate long-term effectiveness and could be added to the activelifestyle and sports participation intervention because these stra-tegies seem effective for maintaining long-term lifestyle inter-vention effects.38 We found improvements of 10% to 30% for theintervention group on outcomes of cardiopulmonary fitness. Thisis reasonable when compared with previously published results onintervention studies,39 especially when the low training frequencyof the active lifestyle and sports participation intervention is takeninto account. These effects may contribute to higher PA levels bylowering the physical strain of daily activities.6

Participants completing the active lifestyle and sports partici-pation intervention experienced decreases in waist circumference

Control Group Intervention Group P

29 28 NA

15/14 12/16 .50

20�3 20�3 .64

65�18 70�18 .24

170�9 169�11 .66

15/14 14/13 .79

16/9/3/1 17/9/2/0 .75

2533�824 2260�725 .25

79�12 87�15 .04

1482�630 1307�352 .24

466�40 448 .74



Table 3 Outcome measures for intervention and control groups

Outcome Measure Group n, t0/t3/t6/t12 t0 t3 t6 t12


Maximum load (W) I 22/17/21/15 163�64 172�64 174�58 166�63

C 22/20/19/15 183�74 184�77 183�84 188�88

Maximum heart rate (bpm) I 20/17/16/14 185�15 183�23 183�16 184�14

C 19/18/18/15 192�9 190�11 181�20 182�21

VO2peak (mL/min) I 22/17/21/15 2260�725 2515�737 2456�583 2315�519

C 22/20/21/15 2533�824 2553�862 2396�861 2549�864_VO2 on the AT (mL/min) I 20/16/19/14 1488�491 1796�483 1603�551 1706�427

C 20/19/19/13 1664�695 1626�634 1501�481 1953�691

Load on the AT (W) I 20/16/18/14 91�42 111�46 102�48 113�47

C 20/19/16/11 113�58 105�55 103�47 151�65

Oxygen pulse (mL/beat) I 20/17/15/13 13.4�3.6 14.7�3.5 15.5�4.3 14.3�3.5

C 19/17/18/12 14.4�5.0 14.5�4.6 14.3�4.9 15.3�4.9

MaxVE (L/min) I 22/17/16/15 89�32 98�33 94�30 95�240

C 22/20/16/15 101�34 101�33 80.81�31 105�47

Body composition

Weight (kg) I 28/22/23/20 70.3�18.4 74.0�18.5 72.9�17.8 70.7�15.0

C 29/25/22/22 64.6�17.6 66.0�18.2 66.5�18.7 67.4�19.9

Waist circumference (cm) I 28/21/22/18 87�15 86�15 86�14 84�13

C 28/26/25/21 79�12 82�13 82�13 80�15

Sum of skinfolds (mm) I 28/22/23/20 72.4�31.1 69.5�28.8 74.0�33.2 64.8�25.4

C 29/26/24/21 58.9�27.9 61.5�28.1 60.8�29.7 64.8�32.2

Systolic blood pressure (mmHg) I 28/22/23/19 119.9�17.7 121.1�12.3 119.2�13.6 115.9�14.2

C 29/26/24/21 119.4�17.6 117.0�16.8 116.0�16.4 122.9�15.1

Diastolic blood pressure (mmHg) I 28/21/23/19 78.0�9.3 76.0�8.0 77.2�8.3 74.8�11.8

C 29/26/24/21 75.2�8.6 69.9�11.7 77.5�9.2 73.9�10.6

Total cholesterol (mmol/L) I 14/8/10/11 4.17�0.54 4.19�0.52 3.68�0.51 3.27�0.67

C 10/10/12/9 4.58�0.61 4.30�0.63 4.46�0.94 4.32�0.86

HDL cholesterol (mmol/L) I 14/8/10/11 1.29�0.28 1.37�0.22 1.42�0.35 1.41�0.21

C 10/10/12/9 1.44�0.31 1.36�0.33 1.36�0.26 1.44�0.25

Cholesterol ratio (mmol/L) I 14/8/10/11 3.28�0.74 3.15�0.72 2.67�0.42 3.08�0.66

C 10/10/12/9 3.36�0.94 3.35�1.05 3.37�0.94 3.13�0.96

Muscle strength

Hip flexion (n) I 26/21/21/18 417�15 449�160 429�121 501�187

C 25/22/21/19 477�20 474�139 443�153 486�118

Hip abduction (n) I 26/20/19/16 461�15 482�143 469�128 476�108

C 25/21/20/18 483�24 449�176 480�195 508�215

Knee extension (n) I 24/18/18/15 463 (12) 494�126 468�124 494�144

C 25/20/20/19 522�25 484�136 457�147 516�211

Shoulder abduction (n) I 1/1/1/1 222 250 250 282

C 3/3/2/3 267�67 167�41 105�25 139�27

Elbow extension (n) I 1/1/1/1 226 179 191 263

C 3/3/NA/3 198�60 221�68 NA 232�43

NOTE. Data are presented as mean � SD or as otherwise indicated.

Abbreviations: bpm, beats per minute; C, control group; HDL, high-density lipoprotein; I, intervention group; MaxVE, ventilation at maximum exercise;

NA, not applicable; VO2, oxygen consumption.


(t0et3), sum of skinfolds (t6et12), and systolic blood pressure(t6et12) compared with the control group. In contrast with effectson cardiopulmonary fitness, effects on body composition areretained in the long term. A recent study found more hypertensionand obesity in adults with CP than a healthy reference sample.40

Therefore, the active lifestyle and sports participation interven-tion may help participants lower their risk for cardiovasculardisease. Furthermore, our results show that baseline lipid profilesare lower compared with those of a Dutch reference sample.41

Such favorable lipid profiles have also been found in adults with


CP.40 Despite participants having favorable baseline lipid profiles,total cholesterol decreased in the intervention group comparedwith the control group during the follow-up period.

No effects of the active lifestyle and sports participationintervention were found on muscle strength. This lack of a dif-ference is consistent with results from a meta-analysis of resis-tance training protocols, which showed that such interventions areineffective in children and adolescents with CP.42 However, adifferent review found that children and adolescents with CP maybenefit from resistance training.17 These conflicting results led to a


Table 4 Longitudinal GEE results for between-group analyses

Components of Physical Fitness

Difference,

t0et3 P 95% CI

Difference,

t0et6 P 95% CI

Difference,

t6et12 P 95% CI


Maximum load (W) �0.3 .97 �15.5 to 14.9 7.7 .19 �3.8 to 19.2 0.3 .97 �13.2 to 13.7

Maximum heart rate (bpm) 2.53 .52 �5.2 to 10.3 4.1 .35 �4.5 to 12.7 2.9 .40 �3.9 to �9.6

VO2peak (mL/min) 89.3 .35 �98.8 to 277.4 195.2 <.01* 57.3 to 333.1 �118.2 .14 �274.5 to 40.1_VO2 on the AT (mL/min) 299.6 <.01* 94.2 to 505.0 325.5 <.01* 102.4 to 548.5 �219.7 .23 �574.2 to 134.9

Load on the AT (W) 26.5 <.01* 9.1 to 43.9 35.6 <.01* 16.0 to 55.2 �28.8 .30 �61.1 to 17.4

Oxygen pulse (mL/beat) 0.7 .25 �0.5 to 1.8 1.7 .07 �0.1 to 3.6 �1.0 .12 �2.1 to 0.3

MaxVE (L/min) 5.6 .21 �3.1 to 14.3 11.4 .20 �5.4 to 28.1 �7.8 .40 �24.3 to 8.8

Body composition

Weight (kg) 0.5 .51 �1.1 to 2.2 �0.6 .46 �2.2 to 0.9 �0.8 .62 �4.0 to 2.4

Waist circumference (cm) �3.7 .04* �7.2 to �0.2 �2.6 .15 �6.1 to 0.9 0.4 .85 �3.9 to 4.7

Sum of skinfolds (mm) �2.2 .48 �8.4 to 4.0 0.2 .96 �7.6 to 8.0 �11.2 <.01*,y �19.0 to �2.9

Systolic blood pressure (mmHg) 2.9 .40 �3.7 to 9.5 1.5 .68 �5.6 to 8.6 �10.2 .03*,y �19.2 to �1.2

Diastolic blood pressure (mmHg) 5.2 .10 �0.3 to 10.6 �3.0 .24 �7.9 to 1.9 0.7 .83 �6.1 to 7.5

Total cholesterol (mmol/L) �0.18 .27 �0.50 to 0.14 �0.50 .07 �3.22 to �0.01 �0.55 .05*,y �1.04 to �0.07

HDL cholesterol (mmol/L) 0.12 .13 �0.03 to 0.26 0.01 .98 �0.21 to 0.21 0.09 .34 �0.09 to 0.26

Cholesterol ratio (mmol/L) �0.42 .07 �0.88 to 0.04 �0.49 .11 �1.08 to 0.10 0.18 .44 �0.28 to 0.65

Muscle strength

Hip flexion (n) �16.1 .63 �81.3 to 49.2 1.4 .97 �63.0 to 66.0 29.0 .51 �56.5 to 114.5

Hip abduction (n) 2.4 .94 �59.6 to 64.5 �38.6 .17 �93.1 to 15.9 �10.8 .71 �68.1 to 46.5

Knee extension (n) 17.8 .64 �56.7 to 92.4 23.7 .57 �58.6 to 106.1 37.7 .33 �38.0 to 113.4

NOTE. All analyses were adjusted for baseline differences between groups for that particular outcome variable.

Abbreviations: bpm, beats per minute; CI, confidence interval; Difference, difference over time of the intervention group compared with the control group for the specified time intervals; HDL, high-density

lipoprotein; MaxVE, ventilation at maximum exercise; _VO2, oxygen consumption.

* Statistically significant.y P<.05.

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Table 5 Longitudinal GEE results for within-group analyses for both the control group and intervention group and specified per time frame

Outcome Measure

Control Group Intervention Group

Difference P 95% CI Difference P 95% CI

t0et3_VO2 on the AT (mL/min) �52.9 .51 �209.2 to 103.3 218.2 <.01* 58.0 to 378.4

Load on the AT (W) �9.1 .19 �22.6 to 4.5 15.7 .02* 2.7 to 28.6

Waist circumference (cm) 2.1 <.01* 0.6 to 3.6 �2.5 .11 �5.6 to 0.6

t0et6

VO2peak (mL/min) �119.5 .02* �215.8 to �23.3 94.0 .17 �41.7 to 229.6_VO2 on the AT (mL/min) �240.6 .01* �424.5 to �56.7 110.3 .25 �79.1 to 300.0

Load on the AT (W) �25.8 <.01* �44.1 to �7.6 13.6 .05 �0.2 to 27.3

t6et12

Sum of skinfolds (mm) �3.2 .24 �8.5 to 2.1 8.0 .01* 1.6 to 14.3

Systolic blood pressure (mmHg) �7.3 .06 �14.8 to 0.2 2.8 .29 �2.4 to 8.0

Total cholesterol (mmol/L) 0.26 .10 �0.1 to 0.6 �0.3 .17 �0.7 to 0.1

Abbreviations: CI, confidence interval; Difference, difference over time within groups; _VO2, oxygen consumption.

* Statistically significant.


study, which aimed to optimize resistance training protocols forchildren and adolescents with CP.43 The active lifestyle and sportsparticipation resistance training protocol met almost all sugges-tions presented in that optimization study. The lack of improve-ment in muscle strength in the present study may be caused by therelatively low training frequency for the active lifestyle and sportsparticipation intervention.

The results of the within-group analyses in table 5 show thatthe between-group effects in the present study are not alwaysattributable to within-group changes of the intervention group butcan also result from within-group changes in the control group.

The results of the present study suggest that offering a lifestyleintervention has positive results on physical fitness. By offering acombination of fitness training and counseling on daily PA andsports participation, the retention of treatment effects are posi-tively influenced compared with regular fitness training. This of-fers opportunities for clinical practice to maintain physical fitnessafter intervention completion. However, optimization of the activelifestyle and sports participation intervention is required to retaineffects on cardiopulmonary fitness at follow-up. The retention ofresults in the midterm for cardiopulmonary fitness and in the longterm for body composition is likely to be attributable to theoffered counseling sessions on PA and sports. However, the designof the present study is not suitable to attribute results to specificintervention components. This merits more specific testing infuture studies. Furthermore, the present study provided explor-atory results for future studies and study designs.

Study limitations

The 6 participating centers did not have the same breath-by-breathanalyzers available. Therefore, 2 different types of analyzers wereused to determine VO2peak. However, over the study course, eachparticipant was tested with the same equipment, and calibration ofthe analyzing systems was performed prior to each measurement.Furthermore, both applied systems were found to be valid by testingthem against the Douglas bag method, which resulted in explainedvariances of .97 and .96.44,45 Waist circumference was measured ina sitting position in persons using a wheelchair; this method couldhave led to incorrectly high waist circumference measurescompared with those measured in the standing position. However,each participant was measured using the same method over time.


Furthermore, waist circumference was measured during standing inall but 2 participants, which makes this possible measurement errornegligible. Skinfold thickness was measured on the left side of thebody. However, it could be possible that an involved side would nothave the same anthropometric features as a nonimpaired side. Forpractical reasons, nonfasting blood samples were collected. How-ever, evidence exists that fasting minimally alters levels of totalserum cholesterol and high-density lipoprotein cholesterol.46-48

Furthermore, nonfasting values for total serum cholesterol andhigh-density lipoprotein cholesterol are considered to be appro-priate by National Cholesterol Education Program guidelines.49

Because the power calculation was performed on PA, inter-vention effects on physical fitness should be regarded as explor-atory. Loss to follow-up was 29% in the intervention group and24% in the control group (see fig 1). Because of this higher thanexpected dropout rate, a type II error may have occurred in thelongitudinal analysis. Finally, one should be careful to draw strongconclusions from single significant findings because of multipletesting in the present study.

Conclusions

This exploratory study showed that the active lifestyle and sportsparticipation intervention yielded positive short- and medium-termeffects on VO2peak, oxygen consumption, and load on the AT andwaist circumference. Long-term effects were found for sum ofskinfolds, systolic blood pressure, and total cholesterol. Theintervention was ineffective in increasing muscle strength andneeds to be optimized to increase muscle strength and for long-term retention of effects on aerobic capacity.

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Keywords

Cerebral palsy; Intervention studies; Physical fitness; Rehabilitation

Corresponding author

Jorrit Slaman, MSc, Erasmus Medical Center, 0s-Gravendijkwal230, 3015 CE Rotterdam, The Netherlands. E-mail address:[email protected].

Acknowledgments

The following institutions and members of the LEARN 2 MOVEResearch Group contributed to this study: J. van Meeteren, MD,PhD, Department of Rehabilitation Medicine and PhysicalTherapy, Erasmus Medical Center, University Medical Center,Rotterdam; W. van der Slot, MD, PhD, Rijndam RehabilitationCenter, Rotterdam; F. van Markus, MD, Sophia Rehabilitation,The Hague; A. Dallmeijer, Department of Rehabilitation, VUMedical Center, Amsterdam; and the Association of PhysicallyDisabled Persons and their Parents (BOSK).

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