Muscle plasticity in children with cerebral palsy in response to intensive activity: a pilot study

Muscle plasticity in children with cerebral palsy in response to intensive activity: a pilot study
NG MOREAU PHD PT 1, C STANLEY MS 5, J MIROS MPT 3,S SCHOLTES DPT4, S TEEFEY MD 6, J BRUNSTROM-HERNANDEZ MD 2, DL DAMIANO PHD PT 5
1Health Professions, Medical University of South Carolina, Charleston, SC;
2Neurology, Washington University in St. Louis, St. Louis, MO;
3Cerebral Palsy Center, St. Louis Children’s Hospital, St. Louis, MO;
4Physical Therapy, Washington University in St. Louis, St. Louis, MO;
5Rehabilitation Medicine, National Institutes of Health Clinical Center, Bethesda, MD;
6Radiology, Washington University in St. Louis, St. Louis, MO, USA

Background/Objectives: Intensive massed practice is the theoretical framework behind many evidence-based therapies, such as constraint-induced movement therapy, with typical frequency and duration of 6 hour/day for 2 weeks (Taub, 1999). Intensive, activity-based interventions have the potential to increase activity and participation levels in children with CP through specific changes at the muscle level. However, the duration of intensive activity to effect changes in lower extremity muscle architecture in CP is unknown. The purpose of this pilot study was to investigate the effects of an intensive sports and recreation day camp on muscle architecture of the quadriceps (important for upright standing, posture, and gait) and on functional mobility.
Design: Cross-sectional; repeated-measures.
Participants and Setting: Convenience sample of 11 children with CP (age:11.8 ± 3.2 years) within gross motor function classification system (GMFCS) levels I (n=1), II (n=2), III (n=6), IV (n=2) participated in an intensive sports and recreation camp, 6hour/day, 5 days per week performing weight-bearing activities such as soccer, tennis, ice skating, dance, basketball, martial arts, and also swimming. Activities were modified for participants as needed in order to achieve the highest level of activity. Duration of participation varied between 1 and 6 weeks.
Materials/Methods: Cross-sectional area (CSA), muscle thickness, and fascicle angle of the rectus femoris (RF) were measured at 50% of thigh length using ultrasound imaging before and after participation in the camp. Functional measures included the timed 25 ft. walk test and Timed Up and Go (TUG) test for GMFCS levels I-III. Linear regression analysis was used to test the effect of the duration of intensive activity on the percentage change (pre to post) in muscle architecture and functional measures (level=0.05).
Results: The duration of activity significantly predicted the percentage increase in RF CSA (r=0.74) and fascicle angle (r=0.62). The linear increase in CSA was significantly correlated with the increase in fascicle angle (r=0.94). The time to complete the 25 ft. walk test and the TUG was improved as a function of the duration of attendance (r=0.75 and r=0.57).
Conclusions/Significance: Linear increases in CSA and fascicle angle as a function of the duration of activity were accompanied by improvements in functional mobility as measured by the timed 25 ft. walk test and the TUG. Although it is generally accepted that neural adaptations occur in the early stages of muscle loading, the linear increases in CSA indicate that muscle hypertrophy is evident earlier that the literature suggests. These results also suggest that an increase in fascicle angle is one mechanism by which the muscle hypertrophies. Furthermore, intensive lower extremity activity-based intervention of at least 4 weeks appears necessary to invoke measurable changes in both muscle architecture and function. These guidelines may be useful in planning future activity-based interventions for the lower extremity.

 
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