Cerebral palsy (CP) is defined as a group of permanent disorders of the development of movement and posture that cause activity limitation, and are attributed to nonprogressive disturbances that occurred in the developing fetal or infant brain [
Children with CP expend more energy during walking than typically developing children, requiring as much as three times normal values [
Community exercise and physical fitness programs have been found effective in increasing walking ability of children with CP [
The unique benefits of the aquatic environment for children with CP have been reported elsewhere [
Based on these phenomena, it is likely that children with CP could engage in physical activity for a longer duration in the aquatic environment, while conditioning more muscle groups before reaching fatigue, compared to exercising on land. Yet, despite of the opportunities provided by the aquatic environment for improving physiological and motor performance, very limited research has been documented thus far measuring specific outcome effects with regard to walking. Recent aquatic training studies in small samples of children with CP reported some evidence with regard to improving walking endurance [
Therefore, the purpose of this study was to compare the outcomes of an aquatic (AQ) and a land-based (LB) training program on (a) the metabolic cost of walking and (b) gross motor function and locomotor performance in young children with CP.
The study was designed as a two-group training project with convenience sampling. Children with CP from a special kindergarten comprised the AQ group and those from a similar kindergarten in another part of the same city the LB group.
Seventeen children (nine in the aquatic intervention group and eight in the land based exercise group) with cerebral palsy (spastic diplegia) ages 3–6 entered the study. All children met the following inclusion criteria: (a) medical diagnosis of cerebral palsy of the spastic diplegic type based on a physician’s assessment; (b) no other medical complications, such as seizures; (c) had an ability to comprehend instructions; (d) placed in a special education setting supervised by the Israeli Board of Education; (e) did not have any medical procedures involving the lower limbs in the last 12 months (including casting or Botulinum toxin injections); (f) able to walk three minutes at a self paced speed; (g) had functional performance levels between I–III of the GMFCS [
Individual criteria of participants across the aquatic and exercise intervention groups at the pretest.
ID | Gender | Age (Yrs: M) | Mass (kg) | Stature (cm) | GMFCS |
---|---|---|---|---|---|
Aquatic exercise group | |||||
1 | M | 03.05 | 13.6 | 105 | I |
2 | M | 04.10 | 18.4 | 111 | III |
3 | M | 05.02 | 19.4 | 111 | II |
4 | M | 05.04 | 14.3 | 111 | II |
5 | F | 06.05 | 20 | 110 | II |
6 | F | 06.0 | 16 | 100 | III |
Land-based exercise group | |||||
1 | F | 06.05 | 16.5 | 116 | III |
2 | F | 04.08 | 14.7 | 108 | II |
3 | M | 03.11 | 17 | 108 | I |
4 | F | 04.03 | 12.8 | 110 | II |
5 | F | 04.03 | 12 | 100 | III |
Direct metabolic measurement while walking was performed by means of the Cosmed (Rome, Italy) K4 b2 system. This is a portable breath by breath metabolic measuring and recording system. The K4 b2 system uses a facemask, with turbine flow meter and oxygen electrode. The child carried a gas sampler and a telemetry transmitter, together with a battery pack, which were carried using a special harness. The total weight of the carried equipment was about 800 g. A mobile receiver and data processing system were carried separately by a technician. The K4 b2 has been validated and found reliable [
This procedure was favored over stationary treadmill testing, mainly due to the fact that it enables the child to be tested while walking, self paced on the floor, with his or her own locomotor aids, rather than on the treadmill, which is an externally paced device for which specific training and habituation are required [
The individual fitting procedure was initiated by fitting the child with a Polar (Electro, Finland) S610 heart rate monitor. Following this, the metabolic apparatus was fixed. Once the mask was properly adjusted, the child was asked if he or she was comfortable. The measurement started when the child was asked to sit for a period of three minutes or until predictive resting values of HR were observed. Following the rest period, the child was asked to walk at a self paced speed with shoes and walking aids following the oval track until steady state values were observed by the technician. As the continuous metabolic responses were observed, the child was assisted to the straight line and continued to walk the 34 m without stopping. At the end of this line, the child was seated for recovery until HR values reached the resting values. Metabolic cost of walking (MCW) (mL·meter−1) was calculated by dividing the oxygen consumption (VO2-mL/min) by the speed (
This test was selected because it is one of the most popular activity outcome measures for children with CP [
Physiotherapists in each kindergarten administered the 66 item version of the Gross Motor Function Measure (GMFM) [
The PEDI [
Children in the AQ participated in an ongoing adapted aquatics program for children of the participating kindergarten. Children in the LB exercise group did not receive aquatic sessions, but maintained a land-based exercise program. Post-test measures were recorded after a four-month intervention period, ensuring at least 32 sessions for the participants in each group. All outcome measures were recorded within a three-week period at the pre- and post test measurements. Participants used the same mobility aids during the pre-and post tests. Their weight and stature were measured during each of the test periods.
The adapted aquatics program consisted of two weekly individualized 30 min sessions in an indoor heated therapeutic swimming pool (water temperature set at 33-34°C). Each child was assigned to a trained instructor throughout the program. Goals were individually determined, in cooperation with the attending physiotherapist, to meet the specific needs of each participant. A multidisciplinary approach was applied in determining program goals and objectives, with an emphasis on improving functional abilities in the water environment in reference to the Aquatic Independence Measure (AIM) [
Children in the land-based exercise group were placed together in one kindergarten. The children received 30 min of individualized land-based activities twice a week, as part of their educational curriculum, comprised of (a) an additional physiotherapy session once a week which included 15–20 min of full weight bearing treadmill exercise at a comfortable individualized speed (ranging between 0.5–1.0 km·hr−1), enabling the child to walk continuously in full weight bearing conditions and stretching exercises, and (b) an adapted activity program once a week. An exercise instructor supervised the adapted activity program. The program objective was to improve fundamental motor skills, such as walking, stepping over obstacles, climbing, and catching and throwing objects.
Both programs followed an age appropriate approach with an intermittent intensity phases that included four to five bursts of intensive and relaxing activity of two-three minutes each, preceded with a warmup and followed with cooling down of five minutes. According to sample measurements using Polar heart rate (HR) monitors, the HR during the high intensity phases reached 80% of predicted maximal heart rate.
Kolmogorov-Smirnov tests were used to challenge the assumption of normal distribution, and found no threat to parametric statistics. In each group nonparametric statistics were used. Mann Whitney tests were used to compare between groups at the pretest, and Wilcoxon matched pairs signed ranks tests compared pre- and post tests in each group. Percent gain and effect size of the pre to post test outcomes within each group were also calculated [
Mann-Whitney tests did not indicate significant differences between groups at the pre test (
Table
Descriptive outcomes of VO2 (mL/min) during three consecutive intervals of 20 sec and percentages of the last intervals represented by the two first intervals during walking the 34 m line.
Aquatic | Land-based | ||||||
Sec | 0–20 s | 21–40 s | 41–60 s | 0–20 s | 21–40 s | 41–60 s | |
Mean | 415.06 | 430.62 | 404.15 | 383.36 | 395.86 | 390.89 | |
Pre-test | SD | 113.54 | 98.20 | 86.40 | 103.83 | 110.19 | 108.73 |
% of 41–60 | 103 | 107 | 98 | 101 | |||
Mean | 438.03 | 449.25 | 447.54 | 369 | 384 | 392 | |
Post-test | SD | 119.36 | 122.81 | 114.01 | 76.28 | 75.06 | 118.37 |
% of 41–60 | 98 | 100 | 94 | 98 |
Table
Descriptive values of cardio-respiratory outcomes measured during the last min of the 34 m continuous walk for assessing the metabolic cost of walking.
Pre test | Post test | % change | |||
Mean | SD | Mean | SD | ||
Aquatic group | |||||
VO2 (L·min−1) | 0.41 | (0.10) | 0.44 | (0.11) | 7.9 |
VO2Net (L·min−1) | 0.19 | (0.095) | 0.22 | (0.096) | 11.4 |
VO2 (mL·kg−1·min−1) | 24.07 | (4.50) | 26.17 | 6.27 | 8.7 |
MCW (mL*m−1) | 15.54 | (9.16) | 10.57 | (4.18) | −32 |
TTSST (sec) | 229.5 | (97.12) | 153.33 | (37.24) | −33.2 |
| 15.14 | (2.71) | 15.5 | 3.88 | 2.4 |
| 37.94 | (5.76) | 35.47 | (2.87) | −6.5 |
RER | 0.86 | (0.09) | 0.88 | (0.06) | 0 |
HR (Beats*min−1) | 149.7 | (11.7) | 146.6 | (29.0) | −2.1 |
Land-based group | |||||
VO2 (L*min−1) | 0.398 | (0.096) | 0.400 | (0.08) | 0.5 |
VO2Net (L*min−1) | 0.186 | (0.067) | 0.184 | (0.081) | −1.1 |
VO2 (mL* min* kg−1) | 24.89 | (6.59) | 27.08 | (4.63) | 8.8 |
MCW (mL*m−1) | 17.66 | (14.57) | 15.0 | (8.44) | 15.1 |
TTSST (sec) | 204.8 | (59.54) | 193.8 | (39.71) | −5.4 |
VE (L*min−1) | 13.36 | (2.82) | 12.26 | (2.47) | −8.2 |
VE/VO2 | 33.93 | (4.58) | 30.75 | (3.81) | −9.4 |
RER | 0.875 | (0.06) | 0.80 | (0.09) | −8.8 |
HR (Beats*min−1) | 141.8 | (4.46) | 146.7 | (15.58) | 3.5 |
Abbreviations: VO2: Oxygen Consumption; VE: Ventilation; TTSST: time to steady state; RER: Respiratory Exchange Ratio; determined by dividing VCO2 produced by VO2 consumed; HR: Heart Rate.
Comparison of pre to post walking speed during the 34 m walk across groups.
Table
Descriptive values of activity outcomes.
Pre test | Post test | % gain | |||
Mean | SD | Mean | SD | ||
Aquatic exercise group | |||||
10 m FV (m*sec−1) | 0.94 | 0.41 | 1.18 | 0.50 | 21 |
10 m SSV (m*sec−1) | 0.61 | 0.26 | 0.72 | 0.30 | 15 |
GMFM sum (score) | 62.60 | 8.20 | 61.80 | 9.20 | −1 |
GMFM D, E (score) | 61.20 | 7.22 | 67.10 | 17.66 | 10 |
PEDI sum (score) | 58.93 | 4.27 | 62.20 | 7.69 | 6 |
PEDI pt (score) | 67.05 | 15.76 | 73.28 | 15.40 | 9 |
Land-based exercise group | |||||
10 m FV (m*sec−1) | 0.70 | 0.31 | 0.94 | 0.35 | 27 |
10 m SSV (m*sec−1) | 0.47 | 0.29 | 0.76 | 0.25 | 38 |
GMFM sum (score) | 61.34 | 10.12 | 62.34 | 11.52 | 2 |
GMFM de (score) | 61.21 | 10.34 | 62.00 | 12.23 | 1 |
PEDI sum (score) | 57.16 | 2.03 | 56.30 | 1.80 | −2 |
PEDI pt (score) | 67.64 | 12.64 | 59.92 | 17.30 | −11 |
Abbreviations: FV: fast velocity; SSV: self selected velocity; GMFM: Gross Motor Function Measure (Score range from 0–198); PEDI: Pediatric Evaluation of Disability Inventory (Score range from 0–100).
This study attempted to measure the effects of AQ compared to LB interventions on the MCW and locomotor performance in young children with CP. Improving locomotor speed and endurance is expected to enhance the ability of children with CP to participate in school physical activities, since it is likely that teachers and peers would allow them to be included in more formal and informal motor activities. In the following sections the metabolic and locomotor performance outcomes will be discussed.
The first aim of our study was to investigate the effect of the aquatic compared to land-based training on MCW. The main outcome in our small and young sample of children with spastic diplegic CP revealed that AQ intervention seems to be favorable for decreasing MCW. This appears to be a result of increasing walking speed, while maintaining the amount of oxygen consumed during the submaximal walking trial. Participants of the AQ group also decreased the time required to achieve steady state values at post test. While a quantification of the mechanisms underlying performance buildup was beyond the scope of this study, our findings may reflect benefits of the warm water temperature, the viscosity, and the buoyancy effect provided by the aquatic environment. The water viscosity prolongs falling time and enables the participants to experience movement patterns that allow the center of gravity to be momentarily outside the base of support without fearing to fall. These factors have been reported to increase performance, such as in muscular endurance, neuromuscular coordination, and aerobic capacity [
In a recent systematic literature review on exercise programs for children with CP [
The second aim of the study was to establish the effects of an aquatic compared to a land-based intervention on gross motor function and locomotor performance. Previous research [
Our study did not reveal any significant improvement in GMFM and PEDI results in either group. The lack of transfer from the potential metabolic and speed related gains observed in other activity domains may be due to the reduced sensitivity of the GMFM and PEDI ordinal scales compared with the interval scales used for MCW and speed measurements. Other aquatic intervention studies reported varied results. Thorpe and colleagues [
This study had several limitations: (a) the small number of participants in each group impaired the statistical power and the ability to conclude significant effects; (b) due to sampling limitations we were unable to randomize placement of children in each intervention group. Therefore, the ability to generalize to other samples is impaired. However, children in each group were matched as closely as possibly in terms of age, gender and GMFCS levels, and entering locomotor performance did not differ between groups; (c) several participants did not complete the post-test and had to be excluded from the sample. Direct calorimetry with young children with disability is difficult to perform, and some participants were unable to comply for the required periods of time; (d) the lack of a control group that did not train at all may raise the question that maybe the outcomes observed are of physical growth, rather than of training. However, we calculated MCW using the value of VO2 consumed per Kg body mass. In addition, pre-test to post-test measurements of stature and body mass did not show any significant differences. Therefore, it seems unlikely that the changes observed in MCW and walking speed are merely due to growth.
In summary, based on our findings, both aquatic and land-based training influenced performance. Aquatic training appears to impact somewhat more favorably the metabolic cost during steady state walking, mostly due to the higher speed while walking at steady state. Both aquatic and land-based training appear to have impacted speed in short term walking tasks. Further study of the aquatic training environment is required in order to (a) verify the results obtained in this study by means of a larger sample and multiple baseline design, and (b) explore the mechanisms underlying the changes revealed in our and other aquatic intervention studies.
The authors wish to express their gratitude to Amichai Brezner M.D. from the Chaim Sheba Medical Center at Tel Hashomer for his support and ongoing consultation in planning and implementing the metabolic measurement procedures. This paper is based on a chapter of a Doctoral thesis of the first author at the Faculty of Educational Sciences at the Utrecht University in The Netherlands.