Audrey Parent1, Annie Pouliot-Laforte2, Fabien Dal Maso3, Yosra Cherni4, Pierre Marois5, Laurent Ballaz6. 1. Department of Biological Sciences, Université du Québec à Montréal (UQÀM), C.P. 8888, succursale Centre-Ville, Montreal (Quebec), H3C 3P8, Canada; CHU Sainte-Justine (CRME) 5200 rue Bélanger Est, Montreal (Quebec), H1T 1C9, Canada. Electronic address: parent.audrey.2@courrier.uqam.ca. 2. Department of Biological Sciences, Université du Québec à Montréal (UQÀM), C.P. 8888, succursale Centre-Ville, Montreal (Quebec), H3C 3P8, Canada; CHU Sainte-Justine (CRME) 5200 rue Bélanger Est, Montreal (Quebec), H1T 1C9, Canada. Electronic address: pouliot_laforte.annie@courrier.uqam.ca. 3. École de kinésiologie et des sciences de l'activité physique, Faculté de Médecine, Université de Montréal, 2100, boul. Édouard-Montpetit, Bureau 8202, Montreal (Quebec), H3T 1J4, Canada. Electronic address: fabien.dal.maso@umontreal.ca. 4. CHU Sainte-Justine (CRME) 5200 rue Bélanger Est, Montreal (Quebec), H1T 1C9, Canada; École de kinésiologie et des sciences de l'activité physique, Faculté de Médecine, Université de Montréal, 2100, boul. Édouard-Montpetit, Bureau 8202, Montreal (Quebec), H3T 1J4, Canada. Electronic address: yosra.cherni@umontreal.ca. 5. CHU Sainte-Justine (CRME) 5200 rue Bélanger Est, Montreal (Quebec), H1T 1C9, Canada. Electronic address: pierremaroismd@hotmail.com. 6. CHU Sainte-Justine (CRME) 5200 rue Bélanger Est, Montreal (Quebec), H1T 1C9, Canada; Department of Physical Activity Sciences, Université du Québec à Montréal (UQÀM), C.P. 8888, succursale Centre-Ville, Montreal (Quebec), H3C 3P8, Canada. Electronic address: laurent.ballaz@uqam.ca.
Abstract
BACKGROUND: A deterioration of crouch gait was found in a group of children with cerebral palsy (CP) after a short walking exercise. The increased knee flexion reported after a continuous walk could be related with muscle fatigue and muscle strength. AIM: Does muscle fatigue appears at the end of a walking exercise in children with CP who walk in a crouch gait? METHODS: Eleven children with cerebral palsy (GMFCS I to III) who walk in a crouch gait were included. Isometric muscle strength was assessed using a handheld dynamometer. Children were asked to walk for 6 min at comfortable speed. Spatio-temporal, kinematic and electromyographic (EMG) measurements were recorded at the first and the last minute of the 6-minute walking exercise. Muscle fatigue was evaluated using the shift of EMG signals median frequency. RESULTS: There was no significant difference in walking speed, cadence, and step length at the end of the 6mwe. Maximal and mean anterior pelvic tilt decreased and knee flexion increased (p < 0.05). Rectus femoris EMG median frequency decreased (p < 0.05). The median frequency in other muscles did not decrease significantly. Greater hip extensor strength was associated with lesser knee flexion at the end of the 6-minute walking exercise (p < 0.05). SIGNIFICANCE: The increase in knee flexion at the end of the 6-minute walking exercise can be explained by muscle fatigue found in rectus femoris. Hip extensor strength can limit the deterioration of crouch gait after a 6-minute walking exercise representative of daily activities.
BACKGROUND: A deterioration of crouch gait was found in a group of children with cerebral palsy (CP) after a short walking exercise. The increased knee flexion reported after a continuous walk could be related with muscle fatigue and muscle strength. AIM: Does muscle fatigue appears at the end of a walking exercise in children with CP who walk in a crouch gait? METHODS: Eleven children with cerebral palsy (GMFCS I to III) who walk in a crouch gait were included. Isometric muscle strength was assessed using a handheld dynamometer. Children were asked to walk for 6 min at comfortable speed. Spatio-temporal, kinematic and electromyographic (EMG) measurements were recorded at the first and the last minute of the 6-minute walking exercise. Muscle fatigue was evaluated using the shift of EMG signals median frequency. RESULTS: There was no significant difference in walking speed, cadence, and step length at the end of the 6mwe. Maximal and mean anterior pelvic tilt decreased and knee flexion increased (p < 0.05). Rectus femoris EMG median frequency decreased (p < 0.05). The median frequency in other muscles did not decrease significantly. Greater hip extensor strength was associated with lesser knee flexion at the end of the 6-minute walking exercise (p < 0.05). SIGNIFICANCE: The increase in knee flexion at the end of the 6-minute walking exercise can be explained by muscle fatigue found in rectus femoris. Hip extensor strength can limit the deterioration of crouch gait after a 6-minute walking exercise representative of daily activities.