Kenyon, Lisa K. PT, MHS, PCS; Sleeper, Mark D. PT, MS, OCS; Tovin, Melissa M. PT, MA, PhD
Individuals with cerebral palsy (CP) often exhibit decreased levels of physical activity and physical fitness when compared with their peers who are typically developing.1–7 Research studies have found that measures of aerobic capacity,3 anaerobic capacity,6 and muscle strength1,7 are frequently decreased in children and adolescents with CP. Although the reasons for these deficits are not entirely clear, the lower levels of aerobic capacity observed in children with CP may be reflective of ineffective ventilation, compromised circulation, and difficulties with fatigue associated with spastic musculature.3 Research findings have also suggested that the submaximal anaerobic endurance and lower peak muscle power demonstrated by children with spastic CP may be related to quantitative and qualitative differences in spastic musculature.6 Disuse, as a result of decreased activity levels, may also contribute to the decreased anaerobic capacity observed in subjects with spastic CP.6 Although recognizing that muscle weakness in CP is a primary impairment,8 strength deficits in children with CP have been ascribed to decreased central activation,1,7,9,10 altered muscle physiology,7 and secondary myopathy.11–13
According to Verschuren et al,4 exercise programs for children and adolescents with CP have traditionally been avoided because of concerns that the demands of maximal exercise programs could negatively affect movement quality. Such concerns have yet to be validated through research studies. In fact, multiple studies support the use of exercise programs for children with CP and have found such programs to be safe, feasible, and effective.4,14–18 Verschuren et al15 found that children with CP who were randomly assigned to a circuit training program demonstrated significant training effects in aerobic capacity, anaerobic capacity, agility, and quality of life compared with a control group of children with CP. Unnithan et al17 found that a strength and aerobic interval training program for children and adolescents with spastic diplegic CP resulted in significant improvements in aerobic capacity and gross motor function. Dodd et al19 found that a strength training program for children with CP who were ambulatory, with or without an assistive device, resulted in improvements in strength and showed a trend toward improved gross motor function. A systematic review by Mockford and Caulton20 concluded that of the 13 studies reviewed, function and gait in children with CP improved more after isotonic rather than isokinetic exercise and that preadolescent children benefited more from strengthening programs than older children. In a qualitative study by McBurney et al,21 young people with CP who participated in a strength training program reportedly experienced an increased sense of well-being and their participation in school and leisure activities improved.
Despite evidence pointing to the potential benefits of improving the physical fitness levels of children and adolescents with CP, pediatric physical therapists may believe that they lack the time, resources, or knowledge to develop and implement such programs to meet the goals and needs of specific patients.22 The purpose of this case report is to describe the development, implementation, and outcomes of a fitness-related intervention program that addressed the sport-specific goals of an adolescent with CP. Informed consent for physical therapy services and permission to publish this case report were obtained from the participant's legal guardian. Assent was obtained from the participant.
DESCRIPTION OF THE CASE
The participant in this case report was a 16-year-old African American male with spastic diplegic CP. The participant's history was gathered through an interview with his legal guardian. The participant was born at 35 weeks of gestation after an uncomplicated pregnancy. The delivery was complicated by a nuchal cord. He was hospitalized at 4 months of age for an infection. During this hospitalization, he was placed on a ventilator for several weeks and was discharged home on supplemental oxygen after a 2-month hospitalization.
After this extended illness, the participant began to display delays in his motor skills and was subsequently diagnosed with spastic diplegic CP. At 3 or 4 years of age, he underwent bilateral heel cord lengthenings and surgical correction for overlapping toes. Bilateral heel cord lengthenings were repeated at the age of 10. In August 2007, at the age of 14, the participant underwent bilateral hamstring lengthenings. According to his caregiver, before this surgical intervention, the participant had marked difficulty ambulating without support from walls and furniture.
In September 2007, approximately 2½ weeks after his cast removal, the participant started outpatient physical therapy with the first author. At his initial outpatient physical therapy visit, the participant was able to ambulate for short distances with intermittent upper extremity assist. The initial goals of his outpatient physical therapy program were to ambulate independently, perform transitional movements without assistance, and ascend and descend stairs without assistance. The participant responded well to intervention, and by late spring 2008, he was able to ambulate independently on even and uneven surfaces, ascend and descend stairs, jump forward using a slightly asymmetrical pattern, hop on his left foot several times, and hop on his right foot 1 time. Jumping and hopping were skills that the participant reportedly had not previously been able to perform.
In late fall 2008, the participant was functioning at level I of the Gross Motor Function Classification System–Expanded and Revised (GMFCS-ER).23 At that time, he joined his high school wrestling team. This was reportedly the first time that he had participated in an organized team sports activity. In March 2009, he expressed his desire to improve his wrestling performance. Specifically, he wanted to be able to get up and down from the mat more quickly during matches, be able to perform movements more quickly, and improve his strength.
Consistent with his diagnosis of spastic diplegia,8 the participant presented with velocity-dependent increased resistance to passive movements bilaterally in the heel cords, hamstrings, hip internal rotators, hip flexors, and hip adductors. Intermittent ankle clonus was observed bilaterally. A positive straight leg raise and a positive Ely's test result were noted bilaterally indicating tightness in the hamstrings and rectus femoris muscles.24,25 Heel cord tightness was noted with ankle dorsiflexion limited bilaterally to less than −5 degrees with the knees extended.24,26 In a weight-bearing position, the participant's feet were noted to be pronated bilaterally.
Tests and measures for the examination were chosen based on the fitness demands of wrestling, the International Classification of Functioning, Disability, and Health (ICF),27 and the Guide to Physical Therapist Practice.28 Wrestling is a sport that requires a combination of flexibility, strength, power, agility, muscular endurance, and anaerobic conditioning.29 Preparticipation screening was completed using the physical activity readiness questionnaire.30 Answers to all questions on the physical activity readiness questionnaire30 were “no,” indicating that there were no concerns related to an increase in the participant's level of physical activity. Examination results are provided in Table 1. A brief description of the individual testing procedures, including any modifications or changes to the testing protocols, is provided in the Appendix,44 which is available online at http://links.lww.com/PPT/A7.
Given the energy requirements of wrestling,29 assessment of anaerobic power was an essential component of the participant's fitness testing. The muscle power sprint test (MPST)31 is a valid and reliable tool for assessing anaerobic power in children and adolescents with CP who function at levels I or II of the GMFCS. The MPST was chosen over other protocols such as the Wingate32 because the MPST is a field test that does not require any specialized equipment and can be easily performed in the clinical setting.
Agility is defined as the ability to change direction in an effective and efficient manner.31 Agility is an important component of wrestling29 and an area in which children and adolescents with CP frequently demonstrate functional deficits.8,31 The 10 × 5-m sprint test31 has been shown to be a valid and reliable tool to measure agility in children and adolescents with CP who function at a GMFCS level of I or II.
Muscle strength of the trunk and extremities is another important aspect of wrestling performance29 and a functional area of concern for children with spastic CP.8 A literature search revealed that the validity and reliability of strength measurement methods are variable in children and adolescents with CP.16,20,33 To address muscle strength in the lower extremities, 3 functional lower extremity strength tests in a 30-second repetition maximum were used as outlined by Verschuren et al.33 The reliability of these tests for children and adolescents with CP has been established, and the tests require equipment that is readily available in the clinical setting.33 Although the Bruininks-Oseretsky Test of Motor Proficiency, 2nd ed. (BOT-2)34 was not specifically developed for use with children and adolescents with CP, the participant competed in wrestling against adolescents without known disabilities. A comparison of his performance on the strength subtest to the performance of the normative sample provided insights into the obstacles he faced during wrestling matches.
Given that wrestling is an anaerobic activity,29 it was anticipated that the participant's intervention program would focus on anaerobic activities. Partaking in an anaerobic training program however has been shown to potentially improve aerobic capacity both in children who are typically developing and in children with CP.15,35 Concerns have been reported regarding the use of classic treadmill protocols such as the Bruce or the Balke to assess aerobic capacity in children with CP because of gait deviations and related difficulties with increasing gait speed and increasing incline.36 The 10-m shuttle run test36 has been shown to be a valid and reliable tool to assess aerobic power in children and adolescents with CP who function at a level I or II of the GMFCS.
A literature search related to fitness testing in children with CP revealed a trend toward examining outcomes related to the activity component of the ICF.4,15,27 The Gross Motor Function Measure (GMFM-66)37 is an activity measure that is a standardized measure of gross motor function. It was developed specifically for children and adolescents with CP and has been found to be a reliable and valid tool for use with children and adolescents with CP aged 5 months to 16 years.
INTERPRETATION OF THE EXAMINATION RESULTS
As part of the evaluation process,28 examination results were interpreted in light of the participant's goals, history, and functional level. Many of the tests and measures used in the examination process were criterion-referenced measures that provided a baseline of function at the onset of intervention but did not allow for comparison of the participant's performance with the performance of adolescents who are typically developing or of other adolescents with CP. Consultation was provided however by Olaf Vershuren, the principal investigator involved in the development of many of the tests used in this case report. Dr. Vershuren (personal communication, 2009) indicated that based on his experiences with children and adolescents with CP in the Netherlands and Switzerland, the participant's performance on the MPST,31 the 10 × 5-m sprint test,31 and the 10-m shuttle run test36 was below the typical performance of an adolescent functioning at level I of the GMFCS-ER.
The strength subtest on the BOT-2 provided the opportunity to compare the participant's performance with the performance of his age- and sex-matched peers. Scale scores derived from an examinee's raw score on the BOT-2 were used to describe the examinee's level of proficiency on each subtest. Typically, scale scores on the BOT-2 range from 1 to 35 with a mean of 15 and a standard deviation of 5. The participant's scale score on the strength subtest was 6, indicating that his performance on this standardized, norm-referenced measure was considerably different from the mean performance of his age- and gender-matched peers in the normative sample, indicating that he most likely faced wrestling competitors who would achieve higher scores on this subtest.
Description of the Intervention
Intervention activities were chosen based on knowledge of the demands of wrestling, the participant's needs as determined through preintervention testing, and a literature search related to fitness programs for children with CP.4,15,17,20,29 Interventions centered on an interval training program were developed to mimic the anaerobic energy requirements used in wrestling.29 By focusing on the anaerobic system, it was thought that the participant's muscles would become more efficient in producing energy and eliminating metabolic byproducts.38 Studies have also shown that children with CP respond to interval training with improvements in strength, agility, and gross motor function.15,17
All intervention activities were performed with the participant wearing high-top sneakers. Although heart rate is not an accurate indicator of exercise intensity in young children, it becomes a more appropriate indicator in the mid-teen to late teen years.39,40 The intervention program consisted of walking on the treadmill for a 5- to 10-minute warm-up at approximately 50% age predicted heart rate reserve (100 to 110 beats per minute). After this warm-up activity, the participant completed 1 to 2 cycles of an 8-station interval training program. The specific activities used at each station of the interval program are provided in Table 2. Given that wrestling competition consists of three 2-minute periods per match,29 the duration of each activity within the interval program was increased by 15 seconds each week until the desired 2-minute duration was reached. Decisions to progress the duration of the interval activities were based on observations of the patient during the sessions of the previous week and the patient's responses to questions concerning the presence of pain or discomfort. The time between activities within the interval was set to allow for optimal training of the energy systems used in wrestling activities.38 The participant's heart rate during the execution of the interval activities typically ranged from 150 to 160 beats per minute. After the interval training, the participant carried out a 5-minute cool-down at 50% age predicted heart rate reserve. Each session ended with flexibility exercises focusing on the hamstrings, hip flexors, pectoralis muscles, and heel cords to address the flexibility needed to competitively wrestle.29
Intervention frequency and duration were determined based on a review of the literature4,15,17 and the scheduling needs of the family. Intervention was provided at a frequency of 2 times per week over a 10-week period with at least 48 hours between scheduled intervention sessions. Refer Table 3 for an overview of the intervention schedule. The participant was also asked to perform select activities at home on an additional day of the week. These activities included modified oblique sit-ups, push-ups, and activities such as sprinting either while running or when riding the bicycle. During the sixth week of the intervention program, the participant was out of town and did not complete any formal intervention sessions. When he returned to scheduled sessions during the seventh week of the intervention program, the interval activities were performed at the same duration as in week 5. The participant attended all other scheduled physical therapy appointments and participated in a total of 18 intervention sessions. Based on observations that the participant appeared to be having continued difficulties with agility tasks, additional agility tasks were added to the intervention program starting from week 5. These activities included tasks requiring rapid changes in direction with quick, alternating movements of the lower extremities.
Throughout the intervention program, the participant was monitored to ensure that he did not experience any negative consequences from his participation in the intense interval activities. The participant was specifically asked at the beginning and end of each session whether he was experiencing any muscle or joint pain. At no time did he report pain or discomfort. His overall quality of movement did not appear to be negatively affected during the execution of intervention activities.
DESCRIPTION OF THE OUTCOMES
Results of the postintervention testing are listed in Table 1. The participant's scores on all tests and measures were found to be higher after the intervention. As suggested in Table 4, sprint times for the six 15-m sprints in the MPST improved from a pretest range of 3.60 to 5.06 seconds to a postintervention range of 2.90 to 2.97 seconds. His peak anaerobic power, defined as the highest calculated power output,31 improved from a pretest level of 405.36 W to a postintervention level of 595.78 W. Mean anaerobic power over the 6 sprints in the MPST more than doubled from pre- to postintervention testing.
To accurately interpret changes in test scores, the amount of error associated with repeated measurements must be considered.41 Although not readily available for all measurements, SEM values are often useful in interpreting differences between pre- and postintervention test findings. Using SEM values and knowledge of the distribution within the normal curve, therapists can determine the range in which a participant's “true score” would lie if the test were perfectly accurate and free from error.41 SEM values for the MPST, the 10 × 5-m sprint test, and the functional lower extremity strength tests are provided in Table 5. Using these values to assess pre- and postintervention testing scores, the participant's improvement in peak power output of 318.81 W on the MPST and his decrease of 9.32 seconds on the 10 × 5-m sprint test exceed the minimal values needed to reflect change and indicates a true improvement in performance between pre- and postintervention testing. On the functional lower extremity strength tests,33 the participant's improvements of 12 repetitions in the sit-to-stand test and 9 repetitions in both the left and right lateral step-up tests also exceed the minimal values needed to reflect change and indicate a true improvement in the participant's performance between pre- and postintervention testing. The participant's improvement of 2 repetitions in attaining standing through both left and right half-kneel, however, does not exceed the minimal values needed to reflect true change. We therefore cannot be certain that the improvement is reflective of a true change in performance.
The SEM value for the 10-m shuttle run test36 is 0.42 minutes for children at level I of the GMFCS.36 Using the 95% confidence interval, a total increase of 0.84 minutes (2 × 0.42 seconds) would be considered to reflect a true change in performance. Given that this test is scored based on the number of intervals or half intervals completed, further interpretation is necessary to accurately interpret the SEM values. According to Dr. Verschuren (personal communication, 2009), as each level of the 10-m shuttle run test takes approximately 1 minute to complete, an improvement of 1 level (>0.84 minutes) reflects a true change in performance. The participant's improvement of 3.5 levels exceeds the minimal value needed to reflect change and indicates a true change in performance between pre- and postintervention testing.
In a similar manner, SEM values and the related confidence intervals provided in the BOT-2 manual34 allow for interpretation of pre- and posttest scale scores on the strength subtest of the BOT-2. At the participant's age, the 95% confidence interval on the BOT-2 is ±4. Using this confidence interval, his preintervention scale score of 6 indicates that his true scale score lies between 2 and 10 and his postintervention scale score of 10 lies between 6 and 14. Because the confidence intervals include both the pre- and posttest scale scores, we cannot be certain that the changes in his pre- and posttesting scale scores are reflective of true changes in his performance.
The gross motor ability estimator42 was used to score the GMFM-66.37 Based on the information provided by the gross motor ability estimator, the participant's preintervention score of 86.62 and postintervention score of 89.7 were both found to lie within the 95% confidence interval. The change between his pre- and posttesting scores is therefore not necessarily reflective of a true change in his performance. Given that, at pretesting, the participant was able to fully perform 61 of the 66 items per the stated scoring criteria, a ceiling effect may have affected the capacity of the GMFM-66 to accurately detect change at the postintervention testing.41
In addition to the changes in test findings, the participant reported functional gains during the intervention period. At several points during the intervention program, he reported that he was able to transition from the floor to standing more quickly. He also reported that he was able to ride his bicycle faster and for longer distances, run faster, and jump both higher and further. When he returned to wrestling practice during the final week of the intervention program, he reported that he was able to get up from the wrestling mat more quickly and that he was more difficult to bring down during practice wrestling matches. The participant also noted that his ability to perform training tasks such as jumping jacks and push-ups during practice had improved. He even reported that he was beginning to be able to jump rope with his teammates during practice. Informal observations of his movement and function during therapy sessions showed that he appeared to be experimenting more with movement as the intervention program progressed. For example, he would run and leap over mats or run and jump up onto a stack of crash mats, both activities that he had not previously attempted. His confidence in his motor abilities and motivation to participate in therapy sessions also seemed to improve in that he appeared to be more willing to attempt therapeutic tasks and activities.
This case report describes the development, implementation, and outcomes of a fitness-related intervention program that addressed the sport-specific goals of an adolescent with CP. Although not routinely used as part of a pediatric physical therapist examination, the testing procedures used in this case were easy to administer, provided pre- and postintervention measures of the participant's fitness levels, and allowed the therapists to devise an intervention program that addressed the participant's individual needs and goals. Use of tests that emphasized the participation level of the ICF,27 such as the Canadian Occupational Performance Measure,43 may have provided additional outcome information.
At the onset of the intervention program, the participant's performance on many of the fitness tests was thought to be below that of other adolescents with CP who function at level I of the GMFCS-ER. This may relate to the gross motor limitations that he experienced before his hamstring surgery in August 2007 and during his subsequent postsurgical rehabilitation period. At his previous level of function, he may not have been able to achieve activity levels that were of the intensity and duration needed to develop the fitness levels typically associated with an adolescent functioning at level I of the GMFCS-ER.
The outcomes of this intervention program seemed to reach beyond improvements in baseline testing and function. Before starting this intervention program, the participant often required extrinsic motivators to participate in therapy sessions. Once introduced to the concept of a specific program to improve his wrestling, however, his intrinsic motivation to participate in therapy sessions seemed to increase and extrinsic motivators were not needed during any of the testing or intervention procedures. He appeared to be excited by the connection between the therapeutic activities and his personal goals to improve his wrestling and frequently referred to activities as helping his performance in a specific aspect of wrestling.
Similar to the findings of various authors,4,15–17 the intervention program developed and implemented in this case appeared to be safe, feasible, and effective and did not seem to negatively affect the participant's quality of movement. The participant's improvements in aerobic capacity after the completion of an intervention program focused primarily on anaerobic training supports research findings that participating in anaerobic training programs may result in improved aerobic capacity.15,35 The participant's apparent motivation to participate in this individualized, sport-specific exercise program supports concepts raised by McBurney et al21 and further suggest the benefits of focusing intervention programs on patient-specific needs and goals.
Given that a case report lacks the control of a research study, there are many possible alternative explanations for the outcomes achieved in this case. The participant's testing improvements could be related to an increased familiarity with the testing procedures at the postintervention testing. His increased level of physical activity may have occurred without participation in the intervention program. His enthusiasm about the intervention program may have resulted in improved performance. Participation in the intervention may have also bolstered his confidence in his motor abilities and resulted in improvements in motor function.
Despite the absence of a definitive cause-and-effect relationship, the adolescent in this case demonstrated improvements in testing and function after participation in an intervention program that focused on improving his wrestling abilities. The tests used in this case were easy to administer and, coupled with the knowledge of the specific demands of wrestling, allowed for the creation of a sport-specific intervention program. Although the authors recognize that the participant's wrestling performance will continue to be affected by impairments related to his CP, it is our hope that wrestling will continue to provide him with increased opportunities for social interaction and community participation while laying the foundation for an active lifestyle that will help to support him throughout his adult years.
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