Frame Running : enabling health improvements through physical exercise in individuals with cerebral palsy

Abstract: Introduction Cerebral palsy (CP), caused by a damage to the developing brain, is the most common cause of motor disability in childhood. People with CP may have varying degrees of activity limitation, which affect their cardiorespiratory and muscle fitness. The overall aim of the thesis was to study the health effects of Frame Running in individuals with CP and ambulatory difficulties (Gross Motor Function Classification System, GMFCS II-V). Frame Running is an exercise and parasport that enables moderate-to-high intensity physical activity in individuals with severely impaired posture, balance, and motor control. Therefore, study I investigated the effects of a Frame Running training intervention. Study II and IV explore whether the six-minute Frame Running test (6- MFRT) is a valid measure for cardiorespiratory fitness, i.e., maximal oxygen consumption (VO2peak). Finally, determinants (apart from VO2peak) of Frame Running capacity in athletes with CP were explored (study III). Methods Study I involved 15 participants with CP at GMFCS level I-IV, who completed 12 weeks of Frame Running training, with pre and post evaluation of cardiorespiratory endurance (6- MFRT), muscle thickness (ultrasound), and passive range of motion. Study II involved 24 participants with CP at GMFCS level II-IV, who performed the 6-MFRT with measure of cardiorespiratory parameters such as heart rate (HR), oxygen consumption (VO2peak) and respiratory exchange ratio (RER). Study III involved 62 participants with CP at GMFCS level I-V, who completed the 6-MFRT test as a measure of Frame Running capacity. Prior to 6-MFRT multiple specific lower limb impairments and muscle thickness was investigated. Study IV involved 16 participants with CP at GMFCS levels II-V, who performed the 6-MFRT and Frame Running Incremental Treadmill test (FRITT) to compare the cardiorespiratory response and blood lactate levels. Results In study I, Frame Running training improved cardiorespiratory endurance (6-MFRT) with 34%, and muscle thickness of the gastrocnemius in the most affected leg with 9%. There were strong correlations between 6-MFRT distance and VO2peak in both study II and IV, and >75% of the participants reached a (near) maximal exertion based on HR and RER-criteria. Moreover, a strong correlation between the VO2peak obtained during the 6-MFRT and FRITT was observed, with no significant differences in any cardiorespiratory parameters or blood lactate. A backward univariate linear regression analysis indicated that distance, sex, body weight, and height were significant predictors of VO2peak (L/min) during the 6-MFRT (Study IV). The orthogonal partial least square (OPLS) regression analysis revealed a modest degree of covariance in the variables analyzed, and that the variance in the 6-MFRT distance could be predicted with 75% accuracy based on >50 variables measured. Variable Importance in Projection (VIP) analysis indicated hip and knee extensor spasticity (negative effect), and muscle thickness (positive effect) arose as the most important factors contributing to Frame Running capacity (Study III). Conclusion Frame Running is a powerful and effective exercise modality in individuals with CP, promoting health-enhancing cardiorespiratory and peripheral adaptations. The Frame Runner can be used for aerobic exercise testing, where the 6-MFRT is valid and practical. Apart from aerobic capacity, spasticity around the hip and knee (negative effect) and muscle mass (positive effect) appears to be the most important factors contributing to Frame Running capacity. These findings are an important resource to enable optimization of training regimes to improve Frame Running capacity and contribute to evidence-based and fair classification for this parasport.