Changes in Endurance andWalking Ability ThroughFunctional Physical Training inChildren with Cerebral PalsyHetty Gorter, PT, Lian Holty, PT, Eugène E.A. Rameckers, PT, MRes, Hans J.W.H. Elvers, RI, MSc, andRob A.B. Oostendorp, Prof Dr
Roessingh Rehabilitation Centre Enschede (H.G., L.H.), Enschede, The Netherlands; Stichting Revalidatie Limburg(E.E.A.R.), Franciscusoord Valkenburg, The Netherlands; Dutch Institute of Allied Health Care (J.W.H.E.,R.A.B.O.), Amersfoort, The Netherlands; Methodological Health-skilled Institute (J.W.H.E.), Beuningen, TheNetherlands; Radboud University Nijmegen Medical Centre, Department of Public Health and Research (J.W.H.E,R.A.B.O.); Centre for Allied Health Sciences, Department of Quality of Care Research (J.W.H.E, R.A.B.O.),Nijmegen, The Netherlands
Purpose: To investigate the feasibility and effect of a functional physical training program on aerobicendurance and walking ability of children with cerebral palsy. Methods: Thirteen children (8 –13 years,Gross Motor Function Classification System level I or II, with normal intelligence or mild retardation)participated in this study. A functional physical training program addressing aerobic endurance, walkingdistance, walking velocity, and ambulation, consisted of a circuit with 4 stations and lasted 30 minutestwice weekly for 9 weeks. The Bruce, 6-minute-run test, Timed Up and Down Stairs Test, and AmbulationQuestionnaire were administered 2 weeks before the start, immediately after, and 11 weeks after theintervention. Results: Significant improvement in aerobic endurance, walking distance, and ambulationwere observed immediately after the intervention. Maximum treadmill time had improved significantly at11 weeks. Conclusion: A functional physical training improves the aerobic endurance and the functionalwalking ability of children with cerebral palsy. (Pediatr Phys Ther 2009;21:31–37) Key words: aerobicexercise, cerebral palsy, child, exercise therapy, human movement system, physical endurance, physicaltherapy, walking
INTRODUCTION
Children with cerebral palsy (CP) have a decreasedlevel of daily physical activity in comparison with theirhealthy peers.1 Despite physical training and therapy, theydo not use their physical reserve sufficiently during the dayto achieve optimal levels of daily physical activity. Theyhave to train almost 2.5 hours a day to reach the same levelof daily physical activity as their healthy peers.
In addition, individuals with CP need to retain ahigher level of physical fitness than people without impair-ments to resist the natural process of decline because ofboth age and the restricted endurance related to CP.2 Re-duced endurance is the main factor in the decline in walk-ing ability for individuals with CP.3
van den Berg-Emons4 demonstrated that peak aerobicpower does not increase without a specific training pro-gram. In a study by van den Berg-Emons,1 physical trainingfor children with CP involved both a long training periodand training time as well as a high frequency. This demandsa lot of motivation and time of the children to maintain theprogram. A combination of strength training and trainingfocused on aerobic and sometimes anaerobic endurancewas given in the above-mentioned study1 and in otherstudies.2,4 It is not clear which effect can be reachedthrough aerobic training only.
Address correspondence to: Hetty Gorter, PT, Roessinghsbleekweg 33,7522AH Enschede, The Netherlands. E-mail: [email protected]
DOI: 10.1097/PEP.0b013e318196f563
Pediatric Physical Therapy Functional Physical Training in Children with CP 31
The maximum aerobic capacity, VO2max, is an interna-
tionally acknowledged measure of the fitness of the cardiore-spiratory system.5 Baquet et al6 demonstrated that childrencan increase their VO2max through performing a short inter-mittent training program twice weekly for 30-minutes eachsession across 7 weeks. The assumption is that it is the sameresult that would hold for children with CP.
The main problems, which parents often report dur-ing consultative meetings regarding their children, are thechildren’s inability to walk for longer periods, sufficient forfamily trips or shopping, and their slow pace. These chil-dren tend to have busy school programs (which includeswimming, gymnastics, and/or physiotherapy), leavingthem with limited time for extra training during schoolhours. Moreover, as the rehabilitation and/or educationcenter serves a large region, many children’s travel timesare too long for training after school hours, so this is not anoption.
This has led our Rehabilitation center to launch amodified form of physical training. Aimed primarily at im-proving endurance, this 30-minute training is given twice aweek during school hours, based on the study of physicaltraining in healthy preadolescents of Baquet.6
The aim of this study was to investigate differences inaerobic endurance and walking capacity before and afterparticipating in a functional physical training program, fit-ting in the total school and/or therapy program.
MATERIALS AND METHODS
Design
The study is a test–retest repeated measures design.Baseline tests were carried out 2 weeks before training (T0),the actual training took 9 weeks (T1), postinterventiontests were carried out 11 weeks after the training was com-pleted (T2) (Table 1).
Participants
The participants consisted of students at the schoolfor disabled affiliated with the Rehabilitation Centre dur-ing the school year 2004–2005. The children were in-cluded in the study if they had a diagnosis of CP, level I orII according to the Gross Motor Function ClassificationSystem (GMFCS),7 aged between 8 and 13 years at the startof this study and with normal intelligence or mild retarda-tion. The limit of mental retardation was set at IQ of 60, asdetermined by Wechsler.8 All children of the school popu-lation who met inclusion criteria were invited to the study.
Children were excluded if they had had orthopedicsurgery or botox injections within 3 months before this
study or had genetic or neurological abnormalities in addi-tion to CP, or if they had serious behavior problems. Chil-dren were also excluded if they had been involved in con-dition training less than 6 months before this study.
The age range from 8 to13 years was chosen becauseof children below the age of 8 are generally too small for thetraining apparatus that is used. Children above the age of13 were excluded because of the differences that appearbetween boys and girls in muscle power and peak aero-bic endurance as a result of hormonal influences duringadolescence.9
Approval of the Medical Ethics Committee was givenbecause the intervention (training) is already part of therehabilitation program and no invasive therapy took place.
All parents and children signed an Informed Consent.
Intervention
The children trained for half an hour twice weekly for9 weeks. The training consisted of a form of circuit trainingwith 4 stations (Fig. 1). Each workstation consisted of re-petitive exercises. Because the training was focused on aer-obic endurance, the schedule was 3 minutes of effort and 3minutes of rest.9 The training took place once a week in thegym and once a week in the fitness room. A group wascomposed of maximum of 8 children.
The stations in the training session included jumpingon a trampoline, climb/bend/jump/run combinations, bas-ketball circuit, and a run circuit. The other training sessionconsisted of treadmill walking horizontally, treadmillwalking on an incline, steps and exercises on a bicycle. Forthis circuit training, the children were divided into fixedpairs with one instructor for each pair. Every team memberhad a personal card with information about the order, in-tensity of training, and where he or she should be trained(Fig. 2). The outcomes of the Bruce test (HR6) aided indefining the intensity of training in the fitness room.
Every other week the children wore heart rate meters,to determine whether they trained with an intensity of 60%to 70% of their maximum heart rate. The intensity of exer-cises increased with the same heart rate. In the gym, thechildren were required to talk during the exercises. Bychoice of the exercises, the children could see if theyachieved improvement.
The group of instructors consisted of 1 physical ther-apist, 1 gym teacher, and 1 or 2 assistants. Both physicaltherapists and gym teachers have experience working withchildren and were well instructed to work with the trainingprotocol.
TABLE 1Design of the Study in Weeks with 3 Measure-Moments, Trainings Period, and Follow-Up Period
T0, pretest: Bruce, 6-minute-run test, Timed Up and Down Stairs Test, MoVra.T1, posttest: Bruce, 6-minute-run test, Timed Up and Down Stairs Test, MoVra.T2, follow-up: Bruce, 6-minute-run test, Timed Up and Down Stairs Test.
32 Gorter et al Pediatric Physical Therapy
During the period of this study, the children followedtheir normal therapy program including sport.
For practical reasons, a 9-week period of interventionwas chosen for the study. This period fits in between twoschool holidays, so the children could train uninterrupted.The training time of 30 minutes is in conformity with theusual therapy time in the centre. The two sessions of train-ing are chosen in consult with the school and take intoaccount both school programs and the availability of thefitness room. To compensate absence there was the possi-bility to train at another session.
Measurements
The Bruce treadmill test10 was used to determine themaximum aerobic capacity and the 6-minute-run test11 wasused to determine walking distance and walking velocity.To measure functional mobility (ambulation), Timed Upand Down Stairs test (TUDS)12 and the Ambulation Ques-tionnaire13 (MoVra) were used. The MoVra focuses on thehome situation of the child.
The child wore his usual walking aids if needed, suchas orthoses, during the Bruce treadmill test, 6-minute-runtest, and the TUDS. All children walked on the treadmillduring a week of baseline measurement to get used to thetreadmill.
Bruce Treadmill Test
The Bruce treadmill test10 is often used for measuringaerobic endurance. In this study, it was decided to use the“half Bruce” protocol because it was considered that chil-dren with CP could adapt better to the smaller steps of thisprotocol. The normative values are not relevant to childrenwith CP. The test was used only to compare the subsequentperformances of the child.
HR6 and the Tmax were used as outcome measure-ments. The measures were not converted into VO2max be-cause an error of 10% to 15% could occur in the calcula-tions.14 Studies have proven the existence of a linearrelation between heart rate and oxygen uptake, so the ratecan been taken as a proxy of the energy cost in normalchildren and children with CP.15
Decrease of HR6 is related to a higher oxygen uptakeand increase of Tmax shows a higher level of sustained en-durance.
Run Test
This test is part of the Motor Performance (Moper)fitness test.16 Jackson et al11 demonstrated that the6-minute run test is a reliable and construct valid test forestimating walking distance. To avoid weather distur-bances, the course was indoors. There are normal valuesavailable for children aged 9 to 17 years.16 The normativevalues were not considered to be relevant because in thisstudy the 6-minute-run test was only used to compare thechild’s performance with his previous one.
Timed Up and Down Stairs Test
The TUDS is a quick, low budget, reliable, and validtest to measure the ambulation (functional mobility) ofchildren aged from 8 to 14 years with and without CP.12
The test is suitable as evaluative measuring-instrument.The validity, compared with the Timed Up and Go, theFunctional Reach Test, and the Timed One Leg Stance ismoderate to high (rs � 0.78, �0.57, �0.77, respectively).A shorter time for going up and downstairs is related to ahigher level of ambulation.
Fig. 1. The stations in the training session included jumping on a trampoline, climb/bend/jump combinations, basketball circuit. and a runcircuit. The other training session consisted of treadmill walking horizontally, treadmill walking on an incline, steps and exercise bicycle.
Pediatric Physical Therapy Functional Physical Training in Children with CP 33
MoVra (Version 1.3)
MoVra is a questionnaire for parents and is developedto measure the extent of limitation in ambulation of chil-dren aged from 2 to 12 year with CP. The MoVra wasdeveloped within the Bolien research project.13 It is a partof an ongoing national study consisting of the scalability,reliability, and validity of the MoVra. Consent was ob-tained from the makers of the test to use the questionnairein connection with this study. The questionnaire in theresearch version (version 1.3) contains 47 questions aboutactivities of daily life, divided into “activities indoors”(such as getting out of bed, walking up and downstairs)and “activities outdoors” (such as walking on unevenground, running, walking outside for half an hour). Par-
ents are asked the extent of difficulty the child experiencesin performing the tasks independently. The normal 9-pointscale of version 1.3 was reduced to a 5-point scale for thepurpose of this study. To process the measurement, everyscale was given a number to facilitate the processing of themeasurement.
Development of MoVra is still incomplete. Informa-tion regarding the reliability, validity, and responsivenesswas not available at the time of this study. In the future,there will be a modification toward a 5-point scale. In thisstudy, the scores of the different questions were countedtogether. The difference in scores per child between T0 andT1 was examined. A higher score is related to a lower levelof ambulation. The total questionnaire (MoVra-overall) as
Fig. 2. Card used to record the duration, heart rate, instelling (velocity), and remarks for each training condition.
34 Gorter et al Pediatric Physical Therapy
well the subdivisions such as activities indoors (MoVra-indoor) and activities outdoors (MoVra-outdoor) wereconsidered. From the questions of activities outside, thosequestions that referred to the specific training activities(MoVra-training) were considered separately.
The parents were only asked to fill in MoVra at thebeginning and straight after the period of the training toavoid overburdening them. All parents returned the com-pleted form.
Together with the MoVra, the parents were askedquestions about other hobbies, sport activities, and finallyevents concerning the child.
Statistical Analysis
Statistix 8.0 was used to process the data.17 Statisticalanalysis was carried out using descriptive statistics (meanand standard deviation, median and range), the Shapiro-Wilks (test of normality), the paired t test (Bruce and runtest), and the Wilcoxon signed-rank Test (TUDS* andMoVra). The differences between T1 and T0, between T2
and T1 and between T2 and T0 with � � 0.05 were alsoexamined.18,19 Analysis of variance (ANOVA) for repeatedmeasures design was used to check if the difference be-tween the results at the three measurement times wassignificant.
RESULTS
Study Group
Fourteen children were invited to participate in thestudy; all parents gave their signed informed consent. Thiswas the maximum number of children that could be con-sidered in the study. The results from one child were ex-cluded from the study because the child underwent a med-ical treatment soon after he had participated in theintervention.
Thirteen children participated in the study: There were 8boys and 5 girls. The mean age was 9.9 years (SD � 1.15). Thechildren had normal intelligence (n � 1) to mild mental re-tardation (n � 12). There were 12 Caucasian childrenand 1 with Chinese parents. All children had a diagnosisof CP and at GMFCS level 1 (n � 12) or level 2 (n � 1).
Results Measures
In the 9 weeks of the intervention period, 12 childrentrained 18 times and 1 child 16 times.
All measurement sessions took place by protocol.
Aerobic Endurance (Bruce)
One child could not sustain exercise for 6 minutes atT0. The results are summarized in Tables 2 and 3. ANOVAfor repeated measures design Bruce HR6, p � 0.02 revealeda significant difference between the 3 measurement ses-sions as a result of time. ANOVA for repeated measuresdesign Bruce Tmax, p � 0.00 demonstrated a significant
difference between the 3 measurement sessions as a resultof time.
The reduction in the HR6 at T1 with regard to T0 wassignificant (p � 0.01). There was no significant differencein HR6 between T2 and T1 (p � 0.60) and the HR6 at T2 wassignificantly lower than at T0 (p � 0.01). There was nosignificant difference between Tmax at T1 and T0 (p � 0.12),at T2 the Tmax significantly increased with regard to T1 (p �0.00). The Tmax at T2 was significantly higher than at T0
(p � 0.00).
Walking Distance and Walking Velocity (6-Minute-Run Test)
The results are summarized in Tables 2 and 4.ANOVA for repeated measures design for the run test (p �0.06) revealed the difference between the 3 measurementsessions as a result of time was not significant. But whenlooking at the results separately, the differences betweenboth T1 and T0 as T2 and T0 were significant. The walkingdistance at T1 was significantly more than at T0 (p � 0.03);there was no significant difference in distance between T2
and T1 (p � 0.22). The walking distance at T2 was signifi-cantly more than at T0 (p � 0.03).
Ambulation (TUDS, MoVra)
The results are summarized in Tables 2, 4, and 5. Theresults of the TUDS were not normally distributed. Thedifferences of the 3 outcomes of 1 child are not included inthe calculation of ANOVA, because these are significantlydifferent from the other outcomes.
ANOVA for repeated measures design TUDS (n � 12;p � 0.00) revealed a significant difference in time betweenthe 3 measurement sessions as a result of time. The time atT1 was significantly decreased with regard toT0 (p � 0.00);the difference in time between T2 and T1 was not significant(p � 0.94). The time at T2 significantly decreased withregard to T0 (p � 0.00). The manner of walking up thestairs (using the banisters or not) did not change.
The difference in scores on the MoVra-overall (p �0.38), the MoVra-indoor (p � 0.32) as well as by the MoVra-outdoor (p � 0.17) were not significant (Table 5). The score
* Data from the TUDS were not normally distributed.
TABLE 2Analysis of Variance Table for the Bruce, Run Test, and TUDS
Source DF SS MS F p
Bruce HR6Within 33 4173.42 379.40
5.17 0.015Between 2 1461.50 730.75
Bruce Tmax
Within 36 110.42 9.2010.58 0.001
Between 2 23.19 11.60Run test
Within 36 702234 58519.53.24 0.057
Between 2 13873 6936.6TUDS
Within 33 466.55 42.417.37 0.004
Between 2 40.64 20.32
TUDS indicates Timed-Up and Down Stairs Test.
Pediatric Physical Therapy Functional Physical Training in Children with CP 35
at the MoVra-training was significantly lower (p � 0.03).There were no changes in hobbies or sport activities.
DISCUSSION
The study was executed according to the protocol.The high level of participation of the children gives animpression of the feasibility of the program within ourorganization. No problems were found as well in trainingor during measuring.
The size of the study group was the maximum possi-ble under the inclusion criteria. One child was excludedfrom the study because he underwent a medical treatmentduring the follow-up period but he did participate in theintervention. Twelve of the 13 children from the study
group were classified at GMFCS level I. They had the mostfunctional abilities within the population of children withCP. Hence, caution is required during interpretation of thedata for children with a GMFCS level II.
Looking at the results of this pilot study of changes inaerobic endurance an improvement in VO2max was foundand this improvement is attributed to the intervention,based on the controlled findings from the study by van denBerg-Emons.4 The results of the tests immediately after theintervention showed an improvement in aerobic endur-ance (Bruce HR6), walking distance, and ambulation mea-sured with the TUDS. This improvement was still present11 weeks after the intervention. A possible explanation isthat the children also begin to function at a higher level ofactivity in their home situations. The most common re-mark of the parents was that the children could play out-side with other children for a longer time and that theycould walk for a longer period.
The result of the MoVra, when specifically consider-ing the activities that are trained (MoVra-training), makesthis plausible. Those activities become more part of theirdaily routines, so that the level of daily activities of thechildren increased. This finding was not seen in the resultsof MoVra-overall, MoVra-indoor, or MoVra-outdoor. Onlythe MoVra-training activities demonstrated a significantdifference. This means that specific training is requireddepending on what needs improving.
The maximum treadmill time (Tmax) did not improveimmediately after the intervention. It is possible that the chil-dren need time to get used to longer periods at higher levels ofexertion. This could be an explanation for the fact that after 11
*n � 1 missing.†T1 � T0 significant, HR6: p � 0.0096 Student t test.‡T2 � T0 significant, HR6: p � 0.0147 Student t test; Tmax: p � 0.0004 Student t test.§T2 � T1 significant, Tmax: p � 0.0041 Student t test.HR6 indicates heart rate in the 6th minute; Tmax, maximum treadmill time.
TABLE 4Outcome 6-Minute-Run Test and Timed Up and Down Stairs Test for 3 Measure-Moments
*T1 � T0 significant, p � 0.036 Student t test.†T1 � T0 significant, p � 0.0006 Wilcoxon signed-rank test (results not normally distributed).‡T2 � T0 significant, p � 0.0291 Student t test.§T2 � T0 significant, p � 0.0001 Wilcoxon signed-rank test (results not normally distributed).
TABLE 5MoVra (ambulation questionnaire) for 2 Measure-Moments
*T1 � T0 significant, p � 0.0161 Wilcoxon signed-rank test.MoVra-overall indicates all questions (1 t/m 47); MoVra-indoor,
questions addressed to activities indoors (1 t/m 24); MoVra-outdoor,questions addressed to activities outdoors (25 t/m 47); MoVra-train-ing, questions addressed to activities that are trained (25, 30 t/m 38, 44t/m 47).
36 Gorter et al Pediatric Physical Therapy
weeks there was a demonstrable improvement in the ability tomaintain longer periods of exertion.
Ambulation, measured with the TUDS, improved imme-diately after the intervention, although the ambulation athome, measured with the MoVra-overall, did not improve. Afeasible explanation for this is that parents and child are ha-bituated to a certain measure of assistance and that they couldnot change this pattern of behavior in this short period.
During this period of intervention, there was no ex-change of any information with the parents. In the future,this deserves more attention to bring about use of the ben-efits of the training during daily routines. Parents were notasked to fill in the MoVra questionnaire at the follow-up at11 weeks after the intervention. With hindsight we regretthat these data are not available.
In this study, 3 measure periods were used. Futurestudies should include more measurements during the pe-riod of intervention to have a better look at the individualgrowth of increasing aerobic endurance.
The period of follow-up was relatively short, we can-not be sure what this means for the long-term effects. Thebenefit of the training is not equal in all children because ofthe standard nature of the training. To realize optimumresults for every individual, the training will have to beindividualized.
Feasibility
The organization of all training and measurementswas successful, but much adjustment between school andcenter was needed (availability of fitness room, trainersand testers, school program related to moments of training,and so on). Twelve of the 13 children from the study grouphad mild mental retardation. These children needed muchsupport and stimulation during the training and measure-ments, but all the children were able to complete the inter-vention. A sufficient number of instructors were always avail-able. Because the children could compensate for absencesmost children trained 18 times. The measurements are easy toobtain and the combination of these give sufficient informa-tion about the endurance. Only 1 child could not completethe treadmill test for 6 minutes at the T0 measure.
The children enjoyed the training and stimulated eachother by working in fixed pairs. They could see their im-provement by choice of exercises. The response from par-ents to fill in the MoVra was 100%.
Clinical Implications
This intervention program is feasible within theschool program; however, much adjustment and a suffi-cient number of coworkers are required. If this training willbe continued, this will impact the number of staff needed.All the children enjoyed participating in this training. Theystimulated each other and had a lot of fun. The results ofthis study have led to better communication and adjust-ment within the organization.
CONCLUSION
The research question that was asked in this study,“Does endurance training with a mean frequency of 2 � 30minutes weekly, in the form of circuit training, for 9 weeks,improve the aerobic endurance and the functional walkingability of children, aged between 8 and 13 years with cere-bral palsy, who have independent walking function?”could be answered positively. At the end of the period ofthe study VO2max increased by 9% (estimated from HR6),maximal treadmill time by 23%, walking distance by 7%,and ambulation by 21%. The improvement in ambulationis partially noticeable in the home situation. The trainingfrequency of 2 times weekly for 30 minutes each makes itpossible to contain the endurance training within theschool program. Because of the short period of trainingmore children could profit from the endurance trainingwithin the school facility of the Rehabilitation Centre.
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